Microbubble flows in superwettable fluidic channels

The control of bubble adhesion underwater is important for various applications, yet the dynamics under flow conditions are still to be unraveled. Herein, we observed the wetting dynamics of an underwater microbubble stream in superwettable channels. The flow of microbubbles was generated by integrating a microfluidic device with an electrochemical system. The microbubble motions were visualized via tracing the flow using a high-speed camera. We show that a vortex is generated in the air layer of the superaerophilic surface under laminar conditions and that the microbubbles are transported on the superaerophilic surface under turbulent conditions driven by the dynamic motion of the air film. Furthermore, microbubbles oscillated backward and forward on the superaerophobic surface under turbulent conditions. This investigation contributes to our understanding of the principles of drag reduction through wettability control and bubble flow.

Microbubble flows inside a superwettable channel revealed underwater superwetting phenomena under flow conditions, contributing to the understanding of real-world environmental wetting systems.

Nature offers us ideas for the design of materials with superwettability.¹ In superwettable systems, the wetting of air underwater has generated interest recently.^2–6 For example, penguin feathers are superaerophilic, with an air layer forming on the surface underwater, which allows penguins to swim in the sea with small amounts of drag.^2,3 Inspired by this, researchers have theoretically and/or experimentally studied the influence of wettability on drag reduction underwater.^4–6 In addition, fish scales are superaerophobic, which offers the idea of designing no-bubble adhesion electrodes that demonstrate high and stable oxygen evolution reaction performance.^7,8 However, despite the development of superwettable materials for the controllable adhesion of air and/or bubbles underwater,⁹ the wetting dynamics of bubbles under flow conditions, which we must consider in real environments, have not been investigated.Herein, we generated microbubble flows parallel to superwettable substrates inside a microfluidic device^10,11 and studied the wetting dynamics through integrating an electrochemical setup¹² with a microfluidic device, as shown in Fig. 1. The bubbles were formed through the electrolysis of water (see the ESI^†). Two platinum plates were used: one as the working electrode and the other as the counter electrode. To increase the electrical conductivity, 2.0 mM K₂SO₄ was added to the water. The bath water–vapor interfacial tension, γ_LV, was 71.9 ± 3.6 mN m⁻¹ (n = 15) and the pH of the water was 7.8. We applied a current of ∼0.25 mA cm⁻² to generate microbubbles with a diameter of 463.9 ± 245.1 μm (n = 120). The microfluidic device was generated using a 3D printer and connected to a water-flow generator (see the ESI^† for the dimensions of the device). The microbubbles generated around the electrodes moved in the direction of the water flow and the coated substrates were placed parallel to the flow.Open in a separate windowFig. 1A schematic illustration of the microfluidic device with an electrochemical setup. We generated a flow of microbubbles and investigated the influences of coating wettability and flow type on the microbubbles dynamics via high speed camera observations. Scale bar: 10 mm.We used the microbubbles as tracers and analyzed their flow as well as that of the water (i.e. microbubble image velocimetry), as shown in Fig. 2. We controlled the Reynolds number, Re = 4Q(πDν)⁻¹ (Q is the flow rate of the water, D is the tube diameter, and ν is the kinetic viscosity of the water). Laminar flow was obtained at Re = 79.21 and turbulent flow was obtained at Re = 396.06 (Fig. 2A). Under laminar flow conditions, the flow speed was nearly constant and the flow direction was close to perpendicular to the substrate (φ ≈ 0, where φ is the angle between the microbubble direction of movement and the width direction of the substrate) in all areas; this behavior was time-independent (Fig. 2B and C). Under turbulent flow conditions, the flow speed was not constant, and the flow direction was unstable (φ fluctuated between −180 and 180°) in all areas. We confirmed that the separation of flow did not occur, at least during the observation period, since the flow direction was parallel to the superwetting microfluidic device.Open in a separate windowFig. 2The flow conditions of the microbubbles. We created laminar and turbulent flows through altering the Reynolds number. (A) Flow velocimetry of the microbubbles under laminar (left) and turbulent (right) flow conditions; scale bar: 10 mm. (B) Velocity and flow direction profiles of microbubbles over the flow area under laminar (left) and turbulent (right) flow conditions. (C) Average velocity and flow direction fluctuations with time under laminar (left) and turbulent (right) flow conditions.We then prepared substrate coatings with superaerophilicity and superaerophobicity. Superaerophilic substrates were fabricated according to our previous study.¹² Concisely, a glass plate was dip-coated with a mixture of zinc oxide micro-tetrapod powder for surface roughening and polydimethylsiloxane for aerophilization. Superaerophobic surfaces were prepared through modifying a glass substrate with hydroxy groups using an aqueous potassium hydroxide solution.¹³ The wettability of the superaerophobic surfaces in relation to bubbles was confirmed via measuring the underwater bubble contact angle (θ); the results are shown in Fig. 3. We calculated the adhesion forces of bubbles, F_adh = πl²γ_LV(1 + cos θ)/4,¹⁴ where l is the bubble–solid adhesion length. On the superaerophilic surface, the adhesion force was 3.2 × 10³ μN, and on the superaerophobic surface the force was 4.37 μN for 6 μL bubbles.Open in a separate windowFig. 3Wettability of the coatings. (A) schematic illustration of the measurement of the underwater air contact angle. The contact behavior of 6 μL microbubbles underwater on superaerophilic (B) and superaerophobic (C) surfaces.In Fig. 4, we observed air film formation on superaerophilic surfaces under laminar and turbulent flow conditions. As we have previously shown, when microbubbles are vertically deposited on superaerophilic surfaces, a uniform air layer is formed.¹⁰ In the present study, under both laminar and turbulent flow conditions, a uniform air layer formed on the superaerophilic surfaces, but the air layers grew non-uniformly with the deposition of microbubbles owing to Rayleigh–Taylor instability¹⁴ (Fig. 4A and B). In all five independent observations, the shape of the air layer was non-uniform; thus, the flow of microbubbles influenced the shape of the air layer. However, bubbles with l = 4–7 mm formed on the surfaces under both laminar and turbulent flow conditions.Open in a separate windowFig. 4Microbubble deposition behavior on a superaerophilic surface under laminar (A) and turbulent (B) flow conditions. The top and bottom parts of the images are the initial and time-aged stages, respectively. (C) The vortex motion of microbubbles on deposited air films under laminar flow conditions. (D) Microbubbles transported on a superaerophilic surface under turbulent conditions driven by the dynamic motion of the air film. (E) and (F) Schematic representations of the microbubble behavior from (C) and (D), respectively. All scale bars: 10 mm.After aging for 1000 s, a continuous air film formed on the superaerophilic surfaces under turbulent conditions. However, the shape was unstable and changed with time (Fig. 4D). In Fig. 4C and E, we observe the formation of a vortex on the hemispherical air film under laminar flow conditions (see Movie S1^†). This phenomenon is interesting because under laminar flow conditions a vortex should not be generated (Fig. 2A); this cannot be explained using Bernoulli''s theorem¹⁵ and the generation of a vortex suggests the separation of flows, which works to decrease flow resistance at the interface. Vortex generation may be due to the coalescence of microbubbles with the air layer, causing a change in the curvature of the hemispherical air film. This, in turn, would result in a change in the Laplace pressure of 2Δκγ_LV, where Δκ is the change in curvature. There is a fluctuation in the vertical force torque to generate the vortex, and the force should be balanced by a Kutta–Joukowski force in the form of 2γ_LV dκ/dt ≈ ρΓU, where ρ is the density of flows, Γ is the vortex constant, and U is the velocity of the constant laminar flow.¹⁶In Fig. 4D and F, we observe that microbubbles on the air film were transported as the shape of the air film dynamically changed to a wave-like nature; however, the microbubbles and air film did not coalesce (see Movie S2^†). This indicates that a thin water layer exists between the microbubbles and the air film to prevent coalescence, whereas microbubbles are trapped on the air film by the buoyancy force of the microbubbles, which ≈(Δρ)Ωg, where Δρ is the difference in densities between a bubble and water, Ω is the volume of a microbubble, and g is gravitational acceleration.We then observed the dynamics of the microbubbles on the superaerophobic surfaces (Fig. 5). As we have previously shown, when microbubbles are vertically deposited on superaerophobic surfaces, they are uniformly deposited on the surface and have a spherical shape.¹² Under both laminar and turbulent flow conditions, microbubbles were deposited on the superaerophobic surfaces with spherical shapes but with non-uniform deposition (Fig. 5A and B). We then observed the motion of bubbles in contact with the superaerophobic surfaces. Under laminar flow conditions, microbubbles adhering to the surface moved in the direction of the flow (Fig. 5C and Movie S3^†). In contrast, turbulent flow conditions caused the microbubbles to oscillate backward and forward (Fig. 5D and Movie S4^†). The velocimetry profiles in Fig. 5E and F confirm that the bubble motion is linear in time under laminar flow, but it varies under turbulent flow (with the velocity periodically becoming negative). Despite the periodic negative velocity under turbulent flow conditions, the bubbles go forwards in the flow direction, which is not due to the laminar boundary but because the turbulent flow has more positive components than negative ones. This is because the length of positive motion under turbulent flow conditions increases with the size of the bubbles, obeying Newton''s viscosity law.¹⁷ Thus, we confirmed that the motion of bubbles on superaerophobic surfaces is influenced by the flow conditions. The bubble motion distance on superaerophobic surfaces increased with bubble diameter.Open in a separate windowFig. 5Microbubble deposition behavior on a superaerophobic surface under laminar (A) and turbulent conditions (B). The top and bottom parts of the images are the initial and time-aged stages, respectively. (C) Linear motion of the microbubbles on the surface under laminar flow. (D) The oscillating motion of microbubbles on the surface under turbulent flow. (E) Motion distance and (F) velocity analysis of microbubbles under laminar (left) and turbulent (right) conditions for different bubble diameters (2R). All scale bars: 10 mm.     

TfOH mediated intermolecular electrocyclization for the synthesis of pyrazolines and its application in alkaloid synthesis

TfOH mediated easy access to interesting pyrazolines starting from an aldehyde, phenylhydrazine and styrene has been developed. The scope of this synthetic methodology has been explored by synthesizing various 1,3,5-trisubstituted pyrazolines in very good yields with very high regioselectivity. The origin of regioselectivity has been explained by comparing the stability of possible intermediate carbocations. The synthetic utility of a green solvent has been explored by synthesizing some of pyrazolines in a DES medium. The synthetic application of the present methodology is employed in the synthesis of a pyrazoline alkaloid.

A metal free and green synthetic methodology employing aldehydes, phenylhydrazine and styrene mediated by TfOH has been developed to access 1,3,5-trisubstituted pyrazolines. The synthetic application of the methodology is demonstrated in the synthesis of a pyrazoline alkaloid.

Pyrazoles and pyrazolines are known to exhibit interesting biological and photo-physical behaviours. The biological activities of pyrazoles/pyrazolines have been discussed in several reviews.^1–4 A few representative examples of biologically and medicinally important pyrazoles and pyrazolines are given in Fig. 1.^5–7 In particular, considerable interest has been focused on 1,3,5-trisubstituted pyrazoline derivatives due their potential pharmacological activities including (i) antitubercular activity against the H37Rv strain of Mycobacterium,⁹ (ii) antiproliferative activity,^8,10 (iii) antibacterial activity,^11–13 (iv) antiobesity effect in an animal model of the potent cannabinoid CB1 receptor antagonist,¹⁴ (v) pre-emergent herbicide activity against various kinds of weeds,¹⁵ and (vi) ACE-inhibitory activity with 0.123 mM IC504.¹⁶ Pyrazoline derivatives show enhanced biological activity compared with their corresponding pyrazoles.¹⁷ In addition, the pyrazoline motif is known to exhibit photo-luminescent behaviour due to intra-molecular charge transfer (ICT) in the excited state and also shows hole transport behaviour.^18–24Open in a separate windowFig. 1Representative examples of medicinally important 1,3,5-trisubstituted pyrazolines and pyrazoles.Various synthetic approaches have been developed to access these biologically important 1,3,5-trisubstituted pyrazoline/pyrazole compounds.^25–28 The most general synthetic approach proceeding via a reaction of 1,3-dicarbonyl compounds with arylhydrazines results in poor regioselectivity.^3,29,30 A synthetic method which employs appropriate chalcones and arylhydrazines has been considered to be the most widely accepted method for accessing pyrazolines, but this method falls behind due to a greater number of synthetic steps involved.^31–34 Recently Wang et al. disclosed a methodology proceeding via a three component [3 + 2] cycloaddition using 20 mol% Cu(OTf)₂ at elevated temperature.³⁵ The development of synthetic methodology to prepare active pharmaceutical ingredients (APIs) would preferably involve (i) high regioselectivity, (ii) diversity in substrates, (iii) the least number of synthetic steps involved and (iv) attaining target compounds, free of metal traces. Hence, a regioselective tandem one-pot intermolecular electrocyclization reaction under metal free condition to access 1,3,5-trisubstituted pyrazolines would be of great importance.In this regard, we are disclosing a general, metal free and green synthetic methodology to access diverse pyrazoline derivatives with various functionalities including –NO₂, –OH and aliphatic groups using arylhydrazines, aldehydes and styrenes. We have obtained the corresponding pyrazoline products in very good yields with enhanced regioselectivity. In addition, we have employed this synthetic methodology in the synthesis of a pyrazoline alkaloid (1,5-diphenyl-3-styryl-2-pyrazoline).In our initial studies to attempt metal free conditions, iodine mediated intermolecular electrocyclization of tolualdehyde 1a, phenylhydrazine 2a and styrene 3 was explored (l-proline, CH(OMe)₃, TFA, p-TSA and MeSO₃H (Scheme 1).^36,37 The use of other solvents such as H₂O, DMF, DMSO and ethanol did not result in product formation, as TfOH might be deactivated by these solvents (see ESI, Table S1^†).Optimization of reaction conditions in the synthesis of pyrazoline 4a^a

Base mediated spirocyclization of quinazoline: one-step synthesis of spiro-isoindolinone dihydroquinazolinones

A novel approach for the spiro-isoindolinone dihydroquinazolinones has been demonstrated from 2-aminobenzamide and 2-cyanomethyl benzoate in the presence of KHMDS as a base to get moderate yields. The reaction has been screened in various bases followed by solvents and a gram scale reaction has also been executed under the given conditions. Based on the controlled experiments a plausible reaction mechanism has been proposed. Further the substrate scope of this reaction has also been studied.

A novel approach for the spiro-isoindolinone dihydroquinazolinones has been demonstrated from 2-aminobenzamide and 2-cyanomethyl benzoate in the presence of KHMDS as a base to get moderate yields.

Because of their strong potent biologically activity, heterocyclic compounds have been a constant source of inspiration for the invention of new drugs especially for pharmaceutical and agro chemical industries.¹ Indeed, investigation of novel methods for the synthesis of various natural products and heterocycles has always been a challenging task in modern organic chemistry. Amid all, spiro based scaffolds have been found to be very interesting because of their structural diversity. In spite of their intrinsic structures and immense biological activity there is a tremendous demand for the chemistry of spiro-isoindolinone dihydroquinazolinones.² Indeed, nitrogen containing heterocyclic compounds like spiro-oxindole, spiro-isoindoline, spiro-isoindolinone are playing a significant role in medicinal chemistry and synthetic transformations.³ Moreover these compounds present in many natural products as a core unit like Lennoxamine, Zopiclone, Taliscanine and Pazinaclone (Fig. 1). In addition, many unnatural spiro-isoindolinones show significant biological activities acting as anti HIV-1, antiviral, antileukemic, anesthetic and antihypertensive agents.^4,5 Notably, the spiro-isoindolinone dihydroquinazolinone unit has been found to be a combination of two potent pharmacophore units of dihydroquinazolinone and spiro-isoindolinone. Inspite of their remarkable biological activity afore mentioned, various methods have been developed for their synthesis like lithiation approaches, base mediated protocols, Diels–Alder and Wittig reactions, electrophilic and radical cyclization, metal-catalysed reactions and various electrochemical procedures.⁶Open in a separate windowFig. 1Some biologically active spiro-isoindolinone and quinazolinone units.Previously, a number of metal catalyzed reactions have also been reported for the spiroannulations.⁷ Among all, Nishimura et al. developed an Ir(i) catalyzed [3 + 2] annulation of benzosultam and N-acylketimines with 1,3-dienes via C–H activation for the synthesis of aminocyclopentene derivatives. Further, Xingwei Li et al. developed a Rh(iii)-catalysed [3 + 2] annulation of cyclic N-sulfonyl or N-acyl ketimines with activated alkenes for the preparation of various spirocyclic compounds.⁸ Recently Yangmin Ma et al. developed a one pot nano cerium oxide catalyzed synthesis of spiro-oxindole dihydroquinazolinone derivatives (Scheme 1).^5c However, development of these type of novel compounds is always challenging and more attractive. Indeed, to the best of our knowledge there are no reports for the synthesis of spiro-isoindolinone dihydroquinazolinones. This led us to give more attention to study these compounds.Open in a separate windowScheme 1Different strategies for the synthesis of quinazolinone units.In continuation of our earlier efforts⁹ for the synthesis of various dihydroquinazolinones, herein we would like to report KHMDS mediated synthesis of novel spiro-isoindolinone dihydroquinazolinones. We envisioned the retro synthetic pathway for these compounds, as depicted in Scheme 2. Accordingly these compounds could be synthesised from 2-aminobenzamide and methyl-2-cyanobenzoate or ethyl-2-cyanobenzoate.Open in a separate windowScheme 2Retro synthetic approach for the synthesis of quinazolinone unit.Indeed, in order to understand the reaction conditions, we have commenced the reaction by taking 2-amino-N-hexyl-benzamide (2) and methyl-2-cyanobenzoate (3) as a model substrates. However, in the initial phase of reaction optimisation, we have screened the reaction in different bases (Fig. 2) and to our delight amongst all the bases KHMDS, LiHMDS and NaHMDS were amenable to get moderate yields. However the reaction had not progressed at low temperatures (5 °C) and could improve the yield at room temperature. Moreover the reaction underwent complete conversion with 1.5 equivalents of base. Further, the reaction was also executed with ethyl-2-cyanobenzoate and could replicate the same yield. Incontinuation, the reaction was futile when the reaction was carried out in DIPEA, DBU, K₂CO₃ and Cs₂CO₃. Subsequently, the reaction in NaOMe and ^tBuOK produced exclusively the hydrolysis product (4) of methyl-2-cyanobenzoate (Open in a separate windowFig. 2Base screening in 1,4-dioxane.Optimisation of the base-mediated spiroannulation^a

Palladium mediated domino reaction: synthesis of isochromenes under aqueous medium

Isochromenes have been synthesized using palladium-catalyzed C–C and C–O bond forming reactions starting from ortho-bromo tertiary benzylic alcohols and internal acetylenes. Notably, this domino process is feasible by using the green solvent, water. The protocol exhibited a broad substrate scope and afforded various isochromenes.

Isochromenes have been synthesized using palladium-catalyzed C–C and C–O bond forming reactions starting from ortho-bromo tertiary benzylic alcohols and internal acetylenes.     

Biomimetic synthesis of galantamine via laccase/TEMPO mediated oxidative coupling

Laccase-mediated intramolecular oxidative radical coupling of N-formyl-2-bromo-O-methylnorbelladine afforded a novel and isolable spirocyclohexadienonic intermediate of galantamine. High yield and conversion of substrate were obtained in the presence of the redox mediator 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO). This laccase procedure, with an overall yield of 34%, represents a scalable and environmentally friendly alternative to previously reported syntheses of galantamine based on the use of potassium ferricyanide as an unspecific radical coupling reagent.

Laccase-mediated intramolecular oxidative radical coupling of N-formyl-2-bromo-O-methylnorbelladine afforded a novel and isolable spirocyclohexadienonic intermediate of galantamine.     

DBU mediated one-pot synthesis of triazolo triazines via Dimroth type rearrangement

Herein we report an efficient one-pot synthesis of [1,2,4]triazolo[1,5 a][1,3,5]triazines from commercially available substituted aryl/heteroaryl aldehydes and substituted 2-hydrazinyl-1,3,5-triazines via N-bromosuccinimide (NBS) mediated oxidative C–N bond formation. Isomerisation of [1,2,4]triazolo[4,3-a][1,3,5]triazines to [1,2,4]triazolo[1,5-a][1,3,5]triazines is driven by 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) affording both isomers with good to excellent yields (70–96%).

We demonstrate a simple yet efficient one-pot synthesis of two triazolotriazine isomers via DBU mediated Dimroth type rearrangement with excellent yields.

Purines are nitrogen-containing heterocycles and are structural motifs in the nucleobases adenine and guanine of DNA as well as RNA. Purine nucleotides (ATP, GTP, cAMP, cGMP, NAD, FAD) also act as co-factors, substrates, or mediators in the functioning of numerous proteins.¹ Therefore, bioisosteres of purines are widely explored and exploited by pharmaceutical chemists in developing new drug entities. Heterocycles containig the 1,3,5-triazine ring act as bioisosteres of purine, which exist as two isomers, namely [1,2,4]triazolo[4,3-a][1,3,5]triazine and [1,2,4]triazolo[1,5-a][1,3,5]triazine (Fig. 1), which have been extensively studied as adenosine receptor antagonists,^2,3 as well as for other pharmacological activities^1,4,5 (Fig. 2). Literature reports suggest that [1,2,4]triazolo[1,5-a][1,3,5]triazine has been exploited extensively in drug discovery as compared to its corresponding isomer. Further, from the literature it is evident that symmetrical disubstituted triazines,^6–9 especially morpholine^10–12 substituted, have displayed broad pharmacological activities.Open in a separate windowFig. 1Structure of isomers of triazolo–triazine.Open in a separate windowFig. 2Biologically active molecules of [1,2,4]triazolo[4,3-a][1,3,5]triazine (1) and [1,2,4]triazolo[1,5-a][1,3,5]triazine (2, 3, 4).Various synthetic methods have been reported for the C–N bond formation by employing different starting materials^13–15via oxidative cyclisation,¹⁶ high temperature condition^17–19 and/or metal-catalysed reactions.²⁰ However, the current reported protocols were environmentally unfriendly as they suffered from drawbacks such as, multistep, and tedious procedures, use of carcinogenic solvents, high-temperature, expensive and toxic metal-catalysts, and other hazardous reagents.Furthermore, there is very less reported research on these heterocycles, and that can be because of the unavailability of the efficient and cheaper methods. Thus, there is a need to develop new versatile synthetic method for the synthesis of disubstituted triazolotriazine heterocycles of pharmacological interest.In 1970, for the first time Kobe²¹et al. (scheme a) reported the synthesis of [1,2,4]triazolo[4,3-a][1,3,5]triazine utilizing lead tetraacetate in benzene under reflux conditions (Fig. 3). However, no further Isomerization was carried out and resulted low to moderate yield. Deshpande²²et al. reported (scheme b) the reaction of 2-hydrazinyl-1,3,5-triazine with various substituted benzoic acids. The product formed was treated with P₂O₅, refluxed in xylene for 10h to yield [1,2,4]triazolo[4,3-a][1,3,5]triazine. Further, Isomerization of the resulting product was carried out in 2% methanolic-NaOH solution resulting in poor yields. Recently, Stefano²³et al. (scheme c) reported, a multistep protocol by reacting the intermediate with bis(methyl-sulfanyl)methylenecyanamide at 180 °C under N₂ for 3h resulting in low yield due to the formation of several side products. In addition no isomerization studies were carried out, and only the [1,2,4]triazolo[1,5-a][1,3,5]triazine analogs were reported.Open in a separate windowFig. 3Different approaches for the synthesis of triazolo triazines.Herein, we report an economical one-pot synthesis of [1,2,4]triazolo[1,5-a][1,3,5]triazine analogs via Dimroth type rearrangement of [1,2,4]triazolo[4,3-a][1,3,5]triazine derivatives. This one pot novel methodology was carried out by reacting readily available, inexpensive starting materials such as substituted aryl/heteroaryl benzaldehydes and substituted 2-hydrazinyl-1,3,5-triazine in methanol (a mild solvent)²⁴ at room temperature giving excellent yields of the desired product. For cyclization reaction, an eco-friendly reagent NBS²⁵ was used and the resulting product was treated with DBU to yield its corresponding desired isomer. To the best of our knowledge this is the first report for the greener synthesis of symmetric disubstituted triazolotriazine heterocycles via Dimroth type rearrangement. We believe that this simple, yet novel methodology could be further exploited by the researchers in pharmaceutical industries and academics settings in drug discovery.Formation of the Schiff base was initiated reacting 4,4′-(6-hydrazinyl-1,3,5-triazine-2,4-diyl)dimorpholine 1a and unsubstituted benzaldehyde as shown in Entry no.SolventOxidantBaseBase equiv.Time (hour)Yield%1EtOHNBSDBU1.016682DCMNBSDBU1.01603DMFNBSDBU1.01604MeOHNBSDBU1.016725i-PrOHNBSDBU1.016Trace6H₂ONBSDBU1.01607MeOHNBS——1608MeOHNBS2%NaOH1.016Trace9MeOHNBSK₂CO₃1.016010MeOHNBSTEA1.016011MeOHNBSDABCO1.016012MeOHNBSDBU1.528513MeOHNBSDBU2.01.58014MeOHNCSDBU1.525615MeOHNISDBU1.526116MeOHIBDDBU1.526317MeOHKI/I₂DBU1.525318MeOH/H₂ONBSDBU1.5270Open in a separate window^aConditions: 1a (1 mmol), benzaldehyde (1 mmol), solvent, rt, 20 min, then oxidant (1 mmol), 5 min, rt, then DBU, stir at rt till completion of the reaction.Meanwhile, equivalents of DBU were adjusted (entry 12, 13) to attain the highest yield %. Reaction with 1.5 eq. showed drastic improvement in yields in 2 h whereas 2.0 eq. resulted in good yields with less reaction time. Considering the yield factor (entry 12), the oxidant optimization was achieved (entry 14–17). Using N-chlorosuccinimide (NCS) and N-iodosuccinimide (NIS) (entry 14, 15) offered 56% and 61% yield respectively. When the reaction was performed using phenyliodine(iii) diacetate (PIDA) and KI/I₂ (entry 16, 17) it provided 2a in 63% and 53% yields, respectively. Finally, methanol–water and ethanol–water systems in 3 : 1 were used, which gave approximately 70% yield, concluding that entry 12 gives the best result, demanding alcoholic solvents especially methanol as a key factor for Dimroth type rearrangement. Additionally, it was supported by the observation that reaction goes well in methanol, a little worse in ethanol (Fig. 4. The reaction involves a Schiff base formation (II) by 1a and benzaldehydes, the addition of NBS results in oxidative cyclization reaction to produce isomer 1. The addition of DBU in isomer-1 initiates a famous Dimroth type rearrangement, protonation of III results in ring-opening with the formation of unstable intermediate V. It undergoes tautomerism by 1,3 proton shift, bond rotation and proton abstraction by methoxide ion facilitating the intramolecular cyclization to afford the isomer 2. This reaction mechanism is supported by the formation of the Schiff base, isomer-1, and its conversion to isomer-2, which were easily monitored by TLC, isolated, and characterized (ESI^†). In addition to that, a single crystal of compound 2e was obtained, which further supports the Dimorth type of rearrangement (ESI^†).Open in a separate windowFig. 4Plausible mechanism of the reaction pathway.Having in hand the optimized conditions, the substrate scope was further explored by using different aldehydes (Fig. 5). The reaction was carried out using 1a with benzaldehydes having electron-donating groups (2a-f) followed by NBS and DBU additions. The reaction was allowed to stir at room temperature till reaction completion, as monitored by TLC, which would approximately take 2 h. The reaction could smoothly give final products in excellent reaction yields (79 to 96%). Electron withdrawing groups such as chlorobenzaldehydes (2g-i) despite the position of substitution gave excellent yields (93–95%). With the 4-bromo and different fluoro-benzaldehydes, the reaction resulted in 2j (89%) and 2k-m (84–90%) with very good yields. Also, reaction afforded 70% and 77% yields with heterocyclic aldehydes such as 3-pyridinecarboxyaldehyde (2n) and thiophene-2-carbaldehyde (2o), respectively.Open in a separate windowFig. 5Substrate scope for different aldehydes.The gram scale reaction was performed to further validate this synthetic procedure. The reaction was carried out using 1a (1 g) with benzaldehyde (0.38 g) and stirred for 30 min. The NBS (1.26 g, 1 eq.) was added slowly and stirred till new spot appeared on TLC followed by the slow addition of DBU (1.5 eq.) resulted in isomerisation to give 2a in good yields (1.1 g, 84%) (ESI^†).Encouraged from the potency of the reaction to generate in good to excellent yields [1,2,4]triazolo[1,5-a][1,3,5]triazine analogues, we shifted our investigation to isolate [1,2,4]triazolo[4,3-a][1,3,5]triazine derivatives (isomer-1) as described in Fig. 6. Different aldehydes were reacted with hydrazinyl-1,3,5-triazine analogs (1a, 3a, and 4a) and followed by the addition of NBS, stirred at room temperature till the completion of reaction as monitored by TLC. Compound 1a on reaction with 4-bromobenzaldehyde and NBS resulted in 1b with 90% yield. Similarly, 3a with 4-bromobenzaldehydes and thiophene-2-carbaldehyde afforded 3b and 3c with 84% and 83% yields, respectively. The same reaction was carried out with 4a and 4-bromobenzaldehyde bearing an electron-withdrawing group gave 3d with 87% yield. Further, 4a with aldehydes bearing electron-donating groups resulted 4c and 4d, with 88% and 84% yields, respectively (Fig. 7).Open in a separate windowFig. 6Substrate scope for [1,2,4]triazolo[4,3-a][1,3,5]triazine analogues.Open in a separate windowFig. 7Substrate scope for different disubstituted triazinyl-hydrazine and aldehydes.With these promising results, we explored the scope of aldehydes and 2-hydrazinyl-1,3,5-triazine analogs for the synthesis of [1,2,4]triazolo[1,5-a][1,3,5]triazine derivatives. Compound 3a, when reacted with different aldehydes and employing the optimized protocols gave 5a-e with excellent yields (86–92%) in 2–4 h. Similarly compounds 6a, 6b and 6c, synthesized from 4a also afforded excellent yields 88%, 86% and 90% respectively. Further, substituted cinnamaldehydes were also explored and reacted with 1a followed by the addition of NBS and DBU resulted in 7a and 7b in appreciable yields of 84% and 82%, respectively.Finally, we investigated both the isomers (3b and 5d) spectroscopically, to elucidate the change in proton chemical shifts during rearrangement. Interestingly, it was observed that the proton chemical shift for 5d at the 7th position (Fig. 6) was not affected. However, 5th position of 5d suffers a downfield shift due to change in its electronic environment as compared to its corresponding isomer 3b. In general, the proton chemical shifts for the substitution at 5th position and for the aromatic region was found to be more for isomer-2 as compared to isomer-1.     

Inverted vortex fluidic exfoliation and scrolling of hexagonal-boron nitride

Exfoliation or scrolling of hexagonal boron nitride (h-BN) occurs in a vortex fluidic device (VFD) operating under continuous flow, with a tilt angle of −45° relative to the horizontal position. This new VFD processing strategy is effective in avoiding the build-up of material that occurs when the device is operated using the conventional tilt angle of +45°, where the h-BN precursor and scrolls are centrifugally held against the wall of the tube. At a tilt angle of −45° the downward flow aided by gravity facilitates material exiting the tube with the exfoliation of h-BN and formation of h-BN scrolls then optimized by systematically varying the other VFD operating parameters, including flow rate and rotational speed, along with concentration of h-BN and the choice of solvent. Water was the most effective solvent, which enhances the green chemistry metrics of the processing.

Exfoliation or scrolling of h-BN occurs in a vortex fluidic device under downward continuous flow.     

微流控芯片电泳在快速分离尿蛋白中的临床应用价值

目的　探讨并建立微流控芯片的电泳分离方法 ,用于快速分离尿蛋白。方法　利用照相平板湿蚀刻法在 5cm× 5cm× 0 1cm石英玻片上 ,刻制管道宽度为 70 μm、深度约 4 0 μm的十字形电泳泳道 ,以 5 0 0V为进样电压、2 0 0 0～ 2 5 0 0V为分离电压、pH 10 5的 75mmol/L硼酸缓冲液为电泳液分离尿蛋白。结果　在 2～ 3min完成电泳 ,纯牛白蛋白、人运铁蛋白、人IgG均可得到单一分离峰 ,其混合样品亦可得到较好分离。在 38例尿蛋白阳性患者中 ,用该法检测发现溢出性蛋白尿 3例、选择性蛋白尿 9例、非选择性蛋白尿 2 6例 ,8例健康对照未检出蛋白峰。结论　本法具有快速、简便、检测成本低的特点 ,依据电荷和分子量的不同 ,可将蛋白尿初步分为溢出性蛋白尿、选择性蛋白尿、非选择性蛋白尿 ,有利于临床的诊断和预后判断 ,有较好的应用前景。     

Schoenheimer effect explained--feedback regulation of cholesterol synthesis in mice mediated by Insig proteins

End-product feedback inhibition of cholesterol synthesis was first demonstrated in living animals by Schoenheimer 72 years ago. Current studies define Insig proteins as essential elements of this feedback system in mouse liver. In cultured cells, Insig proteins are required for sterol-mediated inhibition of the processing of sterol regulatory element-binding proteins (SREBPs) to their nuclear forms. We produced mice with germline disruption of the Insig2 gene and Cre-mediated disruption of the Insig1 gene in liver. On a chow diet, these double-knockout mice overaccumulated cholesterol and triglycerides in liver. Despite this accumulation, levels of nuclear SREBPs and mRNAs for SREBP target genes in lipogenic pathways were not reduced. Whereas cholesterol feeding reduced nuclear SREBPs and lipogenic mRNAs in wild-type mice, this feedback response was severely blunted in the double-knockout mice, and synthesis of cholesterol and fatty acids was not repressed. The amount of HMG-CoA reductase protein was elevated out of proportion to the mRNA in the double-knockout mice, apparently owing to the failure of cholesterol to accelerate degradation of the enzyme. These studies indicate that the essential elements of the regulatory pathway for lipid synthesis function in liver as they do in cultured cells.     

Correction: Nano N-TiO2 mediated selective photocatalytic synthesis of quinaldines from nitrobenzenes

Correction for ‘Nano N-TiO₂ mediated selective photocatalytic synthesis of quinaldines from nitrobenzenes’ by Kaliyamoorthy Selvam et al., RSC Adv., 2012, 2, 2848–2855, DOI: 10.1039/C2RA01178F.

The authors regret omitting citations of their related papers in Journal of Molecular Catalysis A: Chemical and Applied Catalysis A: General: ‘Cost effective one-pot photocatalytic synthesis of quinaldines from nitroarenes by silver loaded TiO₂’ (DOI: 10.1016/j.molcata.2011.09.014)¹ and ‘Mesoporous nitrogen doped nano titania—A green photocatalyst for the effective reductive cleavage of azoxybenzenes to amines or 2-phenyl indazoles in methanol’ (DOI: 10.1016/j.apcata.2011.11.011).² The citations should have appeared in the following places as ref. 36 (ref. 1, in the reference list here) and ref. 37 (ref. 2, in the reference list here):In the sentence starting on line 5 of paragraph 5 in the introduction:‘Photocatalytic synthesis of quinolone derivatives from nitrobenzene using TiO₂, metal doped TiO₂ and others had been reported earlier.^1,23–25’At the end of Section 3.12 with the addition of the following sentence:‘This catalyst was also found to be effective for the reductive cleavage of azoxybenzenes to amines or 2-phenyl indazoles in methanol.²’The authors regret that it was not clear in the original article that the bare TiO₂ and N-TiO₂ characterisation data had been reproduced from their related Journal of Molecular Catalysis A: Chemical, Applied Catalysis A: General and Catalysis Communications papers.^1–3 Although the Catalysis Communications article was cited as ref. 25 (ref. 3, in the reference list here) in the original article, it was not made clear that some of the data was reproduced from this article. The appropriate figure captions have been updated to reflect this.Fig. 2: Diffuse reflectance spectra of (a) bare TiO₂, (b) N-TiO₂ and (c) TiO₂-P25. The bare TiO₂ data in Fig. 2a have been reproduced with permission from ref. 1. Copyright 2011 Elsevier. The N-TiO₂ data in Fig. 2b have been reproduced with permission from ref. 2. Copyright 2012 Elsevier.Fig. 3: Photoluminescence spectra of (a) bare TiO₂, (b) TiO₂-P25 and (c) N-TiO₂. The bare TiO₂ data in Fig. 3a have been reproduced with permission from ref. 1. Copyright 2011 Elsevier. The N-TiO₂ data in Fig. 3c have been reproduced with permission from ref. 2. Copyright 2012 Elsevier.Fig. 4: HR-TEM analysis: (a and b) images at two different regions of N-TiO₂, (c) SAED pattern of N-TiO₂, (d) lattice fringes of N-TiO₂ and (e) particle size distribution of N-TiO₂. Fig. 4 has been entirely reproduced with permission from ref. 2. Copyright 2012 Elsevier.Fig. 5: X-ray photoelectron spectra of N-TiO₂: (a) survey spectrum, (b) Ti 2p peak, (c) O 1s peak, (d) N 1s peak and (e) C peak. Fig. 5 has been entirely reproduced with permission from ref. 2. Copyright 2012 Elsevier.Fig. 6: (a) N₂ adsorption–desorption isotherms of N-TiO₂ and (b) its pore size distribution. Fig. 6 has been entirely reproduced with permission from ref. 2. Copyright 2012 Elsevier.Fig. 8: GC-MS chromatograms at different reaction times for the photocatalytic conversion of nitrobenzene with N-TiO₂. Fig. 8 has been entirely reproduced with permission from ref. 3. Copyright 2011 Elsevier.The authors also wish to remove Fig. 1 from the original article due to similarities between two of the spectra and the raw data no longer being available. This does not affect the conclusions as the presence of nitrogen was confirmed by other techniques.The authors also wish to clarify the differences between this RSC Advances paper and the Journal of Molecular Catalysis A: Chemical, Applied Catalysis A: General and Catalysis Communications papers.^1–3 The Journal of Molecular Catalysis A: Chemical paper discusses the photocatalytic synthesis of quinaldines from nitroarenes by silver loaded TiO₂.¹ The Applied Catalysis A: General paper reports the reductive cleavage of azoxybenzenes to amines or 2-phenyl indazoles using mesoporous nitrogen doped nano titania.² The Catalysis Communications paper, ref. 25 in the original article, discusses the synthesis of quinaldines from nitroarenes with gold loaded TiO₂ nanoparticles.³ The original RSC Advances paper discusses the catalytic ability of N-TiO₂ in the synthesis of quinaldines from nitrobenzenes. In each paper, either a different catalyst was used or a different synthetic reaction was investigated.     

高分子材料聚砜膜滤器临床应用及相容性评价

目的:评价高分子材料聚砜膜滤器的性能以及置入体内与宿主的生物相容性,为其在临床上的应用提供参考依据.方法:以"血液透析;透析膜材料;组织相容性;血液相容性;聚醚砜"为中文关键词;以"hemodialysis,dialysis membrane materials:histocompatibility;blood compatibility;polyethersulfone"为英文关键词,采用计算机检索2006-01/2010-03相关文章.纳入与有关生物材料与宿主相容性的文章;排除重复研究或Meta分析类文章.以22篇文献为重点进行探讨聚砜膜滤器材料的性能及应用前景.结果:目前各种新型的膜材料在不断地研发,部分已在临床使用或即将问世,如维生素E修饰的透析膜、多黏菌素B修饰的透析膜、甲壳素膜、以及人肾单位透析器和生物活性膜等.聚砜膜滤器由于具有较好的生物相容性和封堵效果,在临床广泛应用.结论:聚砜膜滤器通过高分子材料滤器强大的对流、黏附作用,高效清除组织损伤过程中产生的炎症递质和毒性代谢产物,排除机体内潴留的多余水分,维持水、电解质、酸碱平衡,实现内环境的稳定,改善重要脏器功能,调节免疫系统.聚砜膜滤器目前虽广泛应用,但不可避免存在着相容不良,引发附近组织发炎,产生病变,造成溶血或凝血现象等.理想的膜滤器材料无论材料本身还是其降解产物都不能产生炎症和毒性反应,所以良好生物相容性的封堵器需进一步开发研制.     

3D printed fittings and fluidic modules for customizable droplet generators

We developed a rapid and simple method to fabricate microfluidic non-planar axisymmetric droplet generators using 3D printed fittings and commercially available components. 3D printing allows facile fabrication of microchannels albeit with limitations in the repeatability at low resolutions. In this work, we used 3D printed fitting to arrange the flow in the axisymmetric configuration, while the commercially available needles formed a flow-focusing nozzle as small as 60 μm in diameter. We assembled 3D printed fitting, needle, and soft tubes as different modules to make a single droplet generator. The design of our device allowed for reconfiguration of the modules after fabrication to achieve customized generation of droplets. We produced droplets of varying diameters by switching the standard needles and the minimum diameter of droplet obtained was 332 ± 10 μm for 34 G (ID = 60 μm). Our method allowed for generating complex emulsions (i.e. double emulsions and compartmented emulsions) by adding 3D printed sub-units with the fluidic connections. Our approach offered characteristics complementary to existing methods to fabricate flow-focusing generators. The standardized needles serving as a module offered well-defined dimensions of the channels not attainable in desktop 3D printers, while the 3D printed components, in turn, offered a facile route to reconfigure and extend the flow pattern in the device. Fabrication can be completed in a plug-and-play manner. Overall, the technology we developed here will provide a standard approachable route to generate customized microfluidic emulsions for specific applications in chemical and biological sciences.

We developed a rapid method to prototype axisymmetric droplet generators using 3D printed fittings and commercially available components. This simple method allowed generating simple and complex emulsions of varying sizes and configurations.     

The Aquilegia pubiflora (Himalayan columbine) mediated synthesis of nanoceria for diverse biomedical applications

Herein, we report an eco-friendly, facile, one-pot, green synthesis of nanoceria for multiple biomedical applications. In the study, cerium oxide nanoparticles (CeO₂-NPs) were synthesized using a simple aqueous extract of Aquilegia pubiflora as an effective reducing and capping agent. The biosynthesized nanoparticles were characterized via UV-vis spectroscopy, X-ray powder diffraction (XRD), high-performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. The NPs were highly stable, exhibited high purity, and had a spherical morphology and mean size of 28 nm. FTIR and HPLC studies confirmed the successful capping of bioactive compounds on the nanoparticles. The well-characterized NPs were evaluated for a number of biomedical applications, and their antimicrobial (antifungal, antibacterial, and antileishmanial), protein kinase inhibition, anticancer, antioxidant, anti-diabetic and biocompatibility properties were studied. Our results showed that the Aquilegia pubiflora mediated CeO₂-NPs were highly active against fungal strains, compared to the tested bacterial strains, with Aspergillus niger resulting in the largest zone of inhibition (15.1 ± 0.27 mm). The particles also exhibited dose dependent leishmanicidal activity with significant LC₅₀ values toward both the amastigote (114 μg mL⁻¹) and promastigote (97 μg mL⁻¹) forms of the parasite Leishmania tropica (KWH23). The NPs were found to be moderately active against the HepG2 cell line, showing 26.78% ± 1.16% inhibition at 200 μg mL⁻¹. Last but not least, their highly biocompatible nature was observed with respect to freshly isolated human red blood cells (hRBCs), making the greenly synthesized CeO₂-NPs a novel candidates for multidimensional medical applications.

Graphical illustration of eco-friendly, facile, one-pot, green synthesis of nanoceria for multiple biomedical applications.     

Copper mediated one-pot synthesis of quinazolinones and exploration of piperazine linked quinazoline derivatives as anti-mycobacterial agents

A facile method was developed for the synthesis of quinazolinone derivatives in a one-pot condensation reaction via in situ amine generation using ammonia as the amine source and with the formation of four new C–N bonds in good to excellent yields. With the optimised method, we synthesized a library of piperazine linked quinazoline derivatives and the synthesized compounds were evaluated for their inhibitory activity against Mycobacterium tuberculosis. The compounds 8b, 8e, 8f, 8m, 8n and 8v showed potent anti-mycobacterial activity with MIC values of 2–16 μg mL⁻¹. All the synthesized compounds follow Lipinski''s rules for drug likeness.

A facile method was developed for the synthesis of quinazolinone derivatives in a one-pot condensation reaction via in situ amine generation using ammonia as the amine source and with the formation of four new C–N bonds in good to excellent yields.     

Efficient synthesis of 1-iodoalkynes via Al2O3 mediated reaction of terminal alkynes and N-iodosuccinimide

Iodination of terminal alkynes using N-iodosuccinimide (NIS) in the presence of γ-Al₂O₃ was developed to afford 1-iodoalkynes with good to excellent yields (up to 99%). This described approach featured excellent chemoselectivity, good functional group tolerance, and utilization of an inexpensive catalyst.

An efficient Al₂O₃-mediated direct iodination of terminal alkynes was developed to afford 1-iodoalkynes.

1-Iodoalkynes are both highly versatile synthons in organic synthesis and valuable building blocks in materials and polymer sciences.^1,2 Traditional procedures for generating 1-iodoalkynes include iodination of metal acetylides (Scheme 1, path a),³ direct iodination of terminal alkynes (path b),⁴ iodination of propiolic acid/trialkylsilylacetylides (path c),^5,6 and a two-step homologation/iodination or elimination sequence from aldehydes or benzylic bromides (path d).^7,8 Among these achievements, path b, the preparation of 1-iodoalkynes from terminal alkynes, is highly desirable. In this regard, various iodinating conditions, including nBuLi/I₂,^4a EtMgBr/I₂,^4b I₂/DMAP,^4c NIS/AgNO₃,^4d NIS/BnN₃,^4e NIS/DBU,^4f NIS/Ag/C₃N₄,^4g KI/CuI/PhI(OAc)₂/Et₃N,^4h Me₃SiI/PhI(OAc)₂,⁴ⁱ CuI/TBAB/Et₃N,^4j TBAI/Oxone,^4k KI/TBHP,^4l TBAI/PhI(OAc)₂,^4m chloramine-B/KI,⁴ⁿ KI/Cu₂SO₄/BPDS,^4o ZnI₂/TBN,^4p NIS/[Au(AIPr)(NEt₃)][HF₂],^4q HMBMIBDCI/DBU,^4r NaI/MeOH/divided cell,^4s and N-iodomorphonine/CuI,^4t have been reported. However, some of these approaches might suffer from expensive metal catalysts, hazardous or toxic reagents, harsh reaction conditions, or generation of wastes that bring about environmental problems, thereby restricting their practical applications. Though considerable progress has been achieved, the development of efficient and environmentally benign protocols is still required.Open in a separate windowScheme 1Approaches towards to 1-iodoalkynes.It is well recognized that solids can play a vital role in developing new cleaner technologies via their capacities to serve as catalysts or support reagents and influence product selectivity, and some books have documented the applications of solids in organic synthesis.^9–11 Aluminum oxide (Al₂O₃) is an inert, odorless and white amorphous material, and has been used as catalyst in various industrial processes for many years.^12,13 But the utilization of aluminum oxide in synthetic organic chemistry especially for halogenation of aromatic compounds and alkynes is very little.^14–18 γ-Aluminum oxide is one of the three common crystal forms of aluminum oxide. Pagni and Kabalka described γ-Al₂O₃ mediated iodination of alkynes and aromatic substrates with I₂ to afford E-diiodoalkenes and iodinated aromatic compounds, respectively.¹⁴ Those iodinations did not occur without the activation of γ-Al₂O₃. N-Iodosuccinimide (NIS) is a well-known iodinating agent and widely used in organic synthesis. Iodination with N-iodosuccinimide (NIS) often needs activating reagents. However, any accompanying reagents used along with iodinating reagents should be easily available to exploit more simple and efficient iodination procedure. Inspired by the indispensable role of γ-Al₂O₃ in the iodination of alkynes and aromatic compounds,¹⁴ we envisioned that γ-Al₂O₃ could activate the N-iodosuccinimide to generate 1-iodoalkynes from terminal alkynes. Herein, we report the γ-Al₂O₃ mediated direct iodination of terminal alkynes for the synthesis of 1-iodoalkynes under mild reaction condition.As shown in †). Similarly, high yields of 1-iodoalkyne 3aa were also obtained when basic and acidic Al₂O₃ were used instead of neutral Al₂O₃ (entry 4–5). Hence, the reaction was further examined in the presence of neutral Al₂O₃. The effort to decrease the reaction temperature to 25 °C only led to low yield (entry 6). Subsequently, we probed different solvents including DMF, THF, EA, MeOH and hexane, but those solvents resulted in poor yields of desired product (entry 7–11). Moreover, the reaction was investigated by varying the amount of Al₂O₃ and NIS to enhance the performance of the reaction (†).Optimization of the reaction conditions^a

国产聚砜膜透析器应用于心脏体外循环手术中的可能性(英文)

背景:进口人工肾价钱昂贵,且存在设计方面的不足,如在滤除水分的同时也丢失了各种中小分子如电解质及葡萄糖等.目的:探讨国产人工肾聚砜膜透析器应用于心脏体外循环手术的可能性.方法:选择的17例患者中瓣膜置换术9例,冠脉搭桥5例,法乐氏四联症2例,右窒双出口1例.于常规的体外循环受过程中,在体外循环动脉端安装微栓过滤器,其顶端三通出口分虽连接泵压表、聚砜膜诱析器入血口和经硅胶管接贮血瓶与氧合器相连,通过调节动脉泵的流量确保动脉压和中心静脉压.以常规体外循环中使用过滤器联合利尿合剂治疗18例为对照.体外循环前后按常规计算预冲液量,并与麻醉师共同维持患者体外循环前后平均动脉压、中心静脉压的稳定.观察体外循环前后患者电解质、葡萄糖及渗透压的变化.结果与结论:聚砜膜透析器在体外循环手术中滤水作用十分明显,效果明显优于对照组,肾透析液中的电解质、尿素氮、葡萄糖和渗透压与使用人工肾前血液中的值无显著差别.提示国产聚砜膜透析器能够代替超滤器应用于体外循环手术中,且效果更理想,为术后心功能恢复和防止其他并发症的发生有良好作用,为一些重症心功能不全、转流时间长、婴幼儿、液体进入体内多而排出尿少等患者提供了另一条出路.     

Sterile and disposable fluidic subsystem suitable for clinical high speed fluorescence-activated cell sorting

BACKGROUND: Applications of fluorescence-activated cell sorting (FACS) are ideally performed under aseptic conditions so that isolated cells can be successfully cultured, transplanted, or processed for the isolation of protein and nucleic acids. However, modern "off-the shelf" flow cytometers are suboptimally designed for these purposes because nonsterile instrument hardware components directly contact sample-harboring fluids, compromising their sterility. METHODS: We have described the design and modular modification of a cytometer with a sterile and disposable FACS fluid handling system that meets requirements of high-speed FACS and good manufacturing practice. This system was tested for functionality and its ability to maintain a clean and sterile fluid environment. RESULTS: Our data have shown that this new fluidic subsystem completely replicated the intended function of the manufacturer's standard fluid handling system, and isolates the fluid from contaminants such as bacteria and fungus, endotoxins, mycoplasma, and helicobacter. CONCLUSIONS: FACS has emerged as a powerful tool used to study and manipulate stem cells. However, if stem cell discoveries are to be fully utilized in clinical transplant medicine, aseptic instrument configurations must be developed. For this purpose, we have designed a disposable sterile fluid handling system.     

Vortex characterization and identification by ultrasound Doppler

The detection of vortices is of potential interest in physiology (e.g. the detection of weak stenoses), and in fluid mechanics. In this paper a non-invasive method of detecting vortices in channel flows using pulsed RF Doppler ultrasound is described. A novel approach involving hybrid operation is taken in implementing a directional Doppler system. A scattering model of a vortex crossing an ultrasound beam is presented and theoretical simulations of the Doppler signals show good agreement with experiment. Experimental results showing the detection of both periodic and isolated vortices in channel flows are given. The Autoregressive or Maximum Entropy Method of spectral estimation is used to obtain the spectral estimates of the Doppler signals over short time intervals. It is shown that these spectral estimates can be used to estimate the velocity profiles of the detected vortices.     

ZIF-95 as a filler for enhanced gas separation performance of polysulfone membrane

Metal–organic frameworks (MOFs) are found to be promising porous crystalline materials for application in gas separation. Considering that mixed matrix membranes usually increase the gas separation performance of a polymer by increasing selectivity, permeability, or both (i.e., perm-selectivity), the zeolitic imidazole framework-95 (ZIF-95) MOF was dispersed for the first time in polysulfone (PSF) polymer to form mixed matrix membranes (MMMs), namely, ZIF-95/PSF. The fabricated ZIF-95/PSF membranes were examined for the separation of various gases. The characterization of solvothermally synthesized ZIF-95 was carried out using different analyses such as powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), porosity measurements, etc. ZIF-95 was mixed with PSF at 8%, 16%, 24%, and 32% weight percent to form different loading MMMs. SEM analysis of membranes revealed good compatibility/adhesion between the MOF and polymer. The permeability of He, H₂, O₂, CO₂, N₂, and CH₄ were measured for the pure and composite membranes. The ideal selectivity of different gas pairs were calculated and compared with reported mixed matrix membranes. The maximum increases in permeabilities were observed in 32% loaded membrane; nevertheless, these performance/permeability increases were at the expense of a slight decrease of selectivity. In the optimally loaded membrane (i.e., 24 wt% loaded membrane), the permeability of H₂, O₂, and CO₂ increased by 80.2%, 78.0%, and 67.2%, respectively, as compared to the pure membrane. Moreover, the selectivity of H₂/CH₄, O₂/N₂, and H₂/CO₂ gas pairs also increased by 16%, 15%, and 8% in the 24% loaded membrane, respectively.

Metal–organic frameworks (MOFs) are found to be promising porous crystalline materials for application in gas separation.