Syntheses of Well‐Defined Glyco‐Polyorganosiloxanes by “Click” Chemistry and their Surfactant Properties

Well‐defined glyco‐polyorganosiloxanes were synthesized by the Cu(I )‐catalyzed Huisgen 1,3‐dipolar cycloaddition reaction (often simply referred to as “click” chemistry). N‐propargylglycosylamines 2 and 4 were first synthesized from cellobiose ( 1 ) and xylogluco‐oligosaccharide XGOs 3 without protecting groups. The azide function was introduced into polydimethylsiloxanes [PDMS: 5 (MD′M) and 7 (M′DM′)] by azidolysis of the counterpart epoxy silicon with NaN₃ to afford the mono‐azido 6 and di‐azido 8 derivatives, respectively. The coupling reaction took place in a hydro‐alcoholic medium in the presence of CuSO₄/sodium ascorbate as catalyst. Only one compound, MD′M‐“click”‐XGO 12 showed good solubility in water with interesting surfactant properties.

     

Influence of Type of Initiation on Thiol–Ene “Click” Chemistry

Thermally and photochemically initiated thiol–ene click reactions using thiol‐ and allyl‐ end functionalized linear polystyrenes with various enes (allyl bromide, methyl acrylate, and methyl methacrylate) and thiol (3‐mercaptopropionic acid) have been investigated. Allyl‐ and thiol‐end‐capped polystyrenes with controlled molecular weight and low polydispersity were prepared by atom transfer radical polymerization (ATRP) of styrene using functional initiator and end group modification approaches, respectively. Thiol–ene reactions can be initiated by both cleavage type photoinitiators such as (2,4,6‐trimethylbenzoyl)diphenylphosphine oxide (TMDPO) and 2,2‐dimethoxy‐2‐phenyl acetophenone (DMPA) and H‐abstraction type photoinitiators such as benzophenone (BP), thioxanthone (TX), camphorquinone (CQ), and classical thermal initiator, 2,2′‐azobis(isobutyronitrile) (AIBN) at 80 °C. The kinetics of the reactions was monitored online with a real time ATR‐FTIR monitoring system and the conversions were determined by ¹H NMR spectroscopy. A comparison of click efficiencies of the studied initiator systems was performed. Compare to the thermal initiators and H‐abstraction type photoinitiators, cleavage type photoinitiators were found to induce thiol–ene click reactions with higher efficiency.

     

In Situ One‐Step Method for Synthesis of “Click”‐Functionalized Monolithic Stationary Phase for Capillary Electrochromatography

Propargyl acrylate‐based functionalizable monolithic stationary phase (FMSP) for capillary electrochromatography, easily modifiable by alkyne–azide 1,3‐dipolar cycloaddition, is developed. Optimization of FMSP is focused on (i) physical properties: rigidity, stability, and pore size and (ii) the ease of capillary preparation and grafting. The effect of grafting is demonstrated on the separation of eleven polycyclic aromatic hydrocarbons (PAHs), three flavonols, and chlorpheniramine before and after derivatization. Two azides are synthesized: the first, cinnamyl azide increases the retention of PAHs and improves separation of flavonols, the second, 6‐azido‐6‐deoxy‐β‐cyclodextrin allows the chiral separation of warfarin, improves the efficiency of PAHs separation and increases retention of chlorpheniramine.     

Self‐Healing Polymer Networks Based on Reversible Michael Addition Reactions

A new polymeric material utilizing a highly efficient as well as reversible thiol‐ene click reaction is presented. For this purpose, a trithiol is reacted with a bisbenzylcyanoacetamide derivative resulting in the formation of a dynamic polymer network. The self‐healing ability of this novel material is tested by scratch healing experiments. Healing is found to take place from 60 °C onward. The underlying healing mechanism is studied in detail using temperature‐dependent Raman spectroscopy confirming the reversible opening of the thiol‐ene adducts. Additionally, the thermal and mechanical properties are investigated by differential scanning calorimetry, thermogravimetric analysis, and rheological measurements proving the network formation as well as its reversibility during the thermal treatment.

     

Metabolic responses in feline “red” and “white” skeletal muscle to shock and ischemia

In order to investigate possible differences in the reaction to hypoxic conditions between “red” and “white” skeletal muscle, cats were subjected to a 2 h period of either hemorrhagic shock or hind limb tourniquet ischemia, and the hypoxia induced changes were studied in the soleus and lateral gastrocnemius muscles. Muscle biopsies were analysed for ATP, CP, glucose, G 6–P and lactate. Using microelectrodes, the resting membrane potential was repeatedly measured. Both experimental models resulted in increased tissue lactate levels and a successive decrease in the membrane potential of both muscles studied. No reduction of the high energy phosphagen content (ATP+CP) occurred in any of the muscles during shock. The tourniquet ischemia resulted in a 40% reduction of the ATP+CP content in the soleus muscle, whereas in the gastrocnemius muscle no significant reduction occurred. A significant correlation was found between the tissue lactate content and the membrane potential under both conditions and in both muscles studied. It is concluded that “red” muscles are more susceptible to metabolic derangement than “white” muscles during total ischemia, whereas during hypovolemia “red” muscles appear to be protected from early hypoxic damage, probably due to a redistribution of skeletal muscle blood flow.     

Microwave Assisted Synthesis of Thiol Modified Polymethacrylic acid and Its Cross‐Linking with Allyl Modified Polymethacrylic acid via Thiol‐ene “Click” Reaction

In this paper, we describe the thiol‐ene “click” reaction with modified poly methacrylic acid in water. The thiol group was implemented by a polymer analogous condensation reaction of polymethacrylic acid ( 1 ) and cysteamine ( 2 ), which was carried out in bulk by use of microwave. The allyl modified polymethacrylic acid ( 5 ) was obtained by DCC‐coupling of the allyl amine onto the polymethacrylic acid backbone. By combination of cysteamine ( 3 ) and allyl modified polymethacrylic acid ( 5 ) the thiol‐ene click reaction could be started with a redox initiator in aqueous solution at room temperature. The kinetics of this reaction were determined by ¹H NMR spectroscopy and the resulting hydrogels were analyzed by rheological measurements and differential scanning calorimetry (DSC).

     

Hypopituitarism and septooptic “dysplasia” in first cousins

Although familial forms of hypopituitarism are known, to our knowledge familial septooptic “dysplasia” in association with hypopituitarism has not been reported. We describe two first cousins with panhypopituitarism, one of whom had septooptic dysplasia. We discuss the possibility that septooptic dysplasia-hypopituitarism may be inherited as an autosomal dominant, or recessive, or multifactorial trait.     

Well‐Defined Miktocycle Eight‐Shaped Copolymers Composed of Polystyrene and Poly(ε‐caprolactone): Synthesis and Characterization

A series of well‐defined miktocycle number‐eight‐shaped copolymers composed of cyclic polystyrene (PS) and cyclic poly(ε‐caprolactone) (PCL) have been successfully synthesized by a combination of atom transfer radical polymerization (ATRP), ring‐opening polymerization (ROP), and “click” reaction. The synthesis involves three steps: 1) preparation of tetrafunctional initiator with two acetylene groups, one hydroxyl group and a bromo group; 2) preparation of two azide‐terminated block copolymers, N₃‐PCL‐(CH?C)₂‐PS‐N₃, with two acetylene groups anchored at the junction; and 3) intramolecular cyclization of the block copolymer through “click” reaction under high dilution. The ¹H NMR, FT‐IR, and gel permeation chromatography (GPC) techniques are applied to characterize the chemical structures of the resulting intermediates and the target polymers. Their thermal behavior is investigated by differential scanning calorimeter (DSC). The decrease in chain mobility of eight‐shaped copolymers restricts the crystallization of PCL.

     

Thermo‐Responsive Brush Copolymers by “Grafting Through” Strategy Implemented on the Surface of the Macromonomer Micelles and Their High Emulsifying Performance

In the present study, the synthesis of water‐soluble thermo‐responsive brush copolymers via “graft through” strategy that is conducted on the surfaces of macromonomer micelles and their application as emulsifiers for thermo‐responsive emulsions are reported. Water‐soluble poly(N ,N‐dimethylacrylmide)‐block‐poly(N‐isopropylacrylmide) (PDMA‐b‐PNIPAM) diblock copolymers carrying a hydrophobic polymerizable vinyl group at the end of the PDMA block are synthesized by reversible addition‐fragmentation chain transfer polymerization and click functionalization. Increasing the temperature to above the low critical solution temperature of the PNIPAM block, the macromonomers self‐assemble to core–shell structure micelles with the polymerizable vinyl terminals on the surface of the micelles. Instead of being directly and freely exposed in the bulk water as the hydrophilic group, the hydrophobic vinyl terminals are protected by the partially looped PDMA segments. PMA‐g‐(PDMA‐b‐PNIPAM) brush copolymers with a high molecular weight and a narrow distribution are obtained by radical polymerization of the macromonomers using the potassium peroxydisulfate as initiator. The radical polymerization only proceeds within the single micelle, and intermicellar propagation and/or termination reactions are totally excluded. These brush copolymers feature the thermo‐responsive conformation transition property and high emulsifying performances for the formation of thermo‐responsive emulsion.

     

Cytogenetic differentiation of Fanconi anemia, “idiopathic” aplastic anemia,and Fanconi anemia heterozygotes

We have analyzed chromosome breaks in 8 patients with Fanconi anemia (FA), 42 with “idiopathic” aplastic anema (AA), 15 first-degree relatives of FA patients, and 13 controls. Their lymphocytes were treated in culture with three concentrations of mitomycin-C (MMC). A 60-fold increase in breaks was observed in FA patients as compared to AA patients, regardless of severity of clinical signs. The MMC-stress test was standardized to clearly differentiate FA from other pancytopenias in doubtful cases. Also, the effect of storage of MMC in solution was investigated. The data on SCEs of 12 subjects tested, 10 mo apart, showed an inverse relationship between length of storage of MMC and chromosome damage. The 10-month-old solution induced only one half as many SCEs as it induced at 4 months. Further, the usefulness and power of diepoxybutane (DEB) in detection of FA heterozygotes was investigated in 12 first-degree relatives of patients with Fanconi anemia and 12 healthy controls. The mean number of chromosome breaks per mitosis by DEB stress in obligate heterozygotes was 0.08 in comparison to 0.06 in controls. Four of twelve control subjects showed proportions of breaks almost identical to or higher than those of FA heterozygotes, ie, 0.12, 0.10, 0.10, and 0.11 breaks per mitosis. The responses of healthy controls to DEB could be separated into two groups: one with mean chromosome breaks of 0.11 per mitosis, and a second with mean breaks of 0.04 per mitosis. Thus, it appears that heterozygote detection by DEB stress of cultured lymphocytes is not unequivocal.     

“Signet‐ring” cells—A caveat in the diagnosis of a diffuse peritoneal mesothelioma occurring in a lady presenting with recurrent ascites: An unusual case report

A diffuse peritoneal mesothelioma is a rare tumor. Exfoliative cytology forms the first step in the diagnosis of mesothelioma, since most of these cases presented with effusion. Despite well established cytomorphological features, a challenge exists in differentiating mesothelial cells, including reactive and malignant types from carcinoma cells and macrophages. Presence of “signet‐ring” cells increases the diagnostic challenge as these can be forms of benign and malignant cells. Ancillary techniques like immunohistochemical (IHC) markers and ultrastructural analysis form useful adjunct in substantiating exact diagnosis. We report an unusual case study of a diffuse peritoneal mesothelioma in a 57‐years‐old lady, with no history of asbestos exposure, presenting with recurrent ascites, diagnosed on ascitic fluid cytology and on histology as an adenocarcinoma, based upon the presence of “signet‐ring” cells. On review, clinicopathological correlation with IHC was helpful in forming correct diagnosis. Diagn. Cytopathol. 2010. © 2009 Wiley‐Liss, Inc.     

Intrafamilial “DOA‐plus” phenotype variability related to different OMI/HTRA2 expression

Dominant Optic Atrophy and Deafness (DOAD) may be associated with one or more of the following disorders such as myopathy, progressive external ophthalmoplegia, peripheral neuropathy, and cerebellar atrophy (“DOA‐plus”). Intra‐ and interfamilial variability of the “DOA‐plus” phenotype is frequently observed in the majority of the patients carrying the same mutation in the OPA1 gene. We are describing two familial cases of “DOA‐plus” carrying the same c.1334G>A (p.Arg445His) mutation in OPA1 and disclosing different clinical, pathological and biochemical features. The two patients showed different expression levels of the mitochondrial OMI/HTRA2 molecule, which acts as a mitochondrial stress sensor and has been described to interplay with OPA1 in in vitro studies. Our data offer the cue to inquire the role of OMI/HTRA2 as a modifier gene in determining the “DOAplus” phenotype variability.     

Synthesis and Photovoltaic Characterization of Dithieno[3,2‐b:2′,3′‐d]thiophene‐Derived Narrow‐Bandgap Polymers

Three novel dithieno[3,2‐b:2′,3′‐d]thiophene‐based low‐bandgap polymers are synthesized by a Suzuki–Miyaura coupling reaction or by direct arylation polycondensation. The polymers present a high molecular weight (26–32 kDa) and narrow polydiversity (1.3–1.7). With a highest occupied molecular orbital (HOMO) energy level around ?5.20 eV, these polymers exhibit a narrow bandgap of 1.75–1.87 eV. All the polymers display strong absorption in the range of 350–700 nm. Bulk‐heterojunction (BHJ) solar cells are further fabricated by blending the as‐prepared polymer with (6,6)‐phenyl‐C₆₁‐butyric acid methyl ester (PC₆₁BM) at different weight ratios. The best devices contribute a power conversion efficiency (PCE) of 0.73% under AM 1.5 (100 mW cm^?2).

     

Polymerization Mechanism in the Presence of 1,1‐Diphenylethylene Part 2: Synthesis and Characterization of PMA and PSt

The polymerization of methyl acrylate and styrene in the presence of 1,1‐diphenylethylene (DPE) is investigated to monitor the impact of different monomers on the structure of DPE‐containing polymers. Poly(methyl acrylate) (PMA) and polystyrene (PSt) with low molecular weight are synthesized and characterized. According to the results of the ¹H nuclear magnetic resonance (¹H‐NMR) spectroscopy, DPE is incorporated into PMA and PSt polymer chains as diphenyl‐substituted structure. The resulting PMA polymers containing only one DPE unit show good agreement with the mass spectrometry results obtained by electrospray‐ionization quadrupolar time‐of‐flight mass spectrometry. The gel permeation chromatography results of PSt polymers are consistent with the molecular weight obtained by ¹H‐NMR, indicating that each PSt polymer chain has only one DPE molecule.