Do the fragments from decomposed ZIF-8 greatly affect some of the intramolecular proton-transfer of thymine? A quantum chemical study

The intramolecular proton-transfer processes of thymine were investigated by the density functional theory method. It is shown that the mutation from keto (T) to enol (T′) form is affected by zeolitic imidazolate framework-8 (ZIF-8) fragments such as single 2-methylimidazole neutral crystals (M), and negatively charged 2-methylimidazole ligands (M⁻). Results show that with the number (n) of water (w) molecules that assist proton-transfer increasing from 1 to 4, the order of the tautomeric energy barriers (in kcal mol⁻¹) is T-2w (16.3) < T-1w (17.6) < T-3w (17.8) < T-4w (20.5). In the presence of M, the order of energy barrier is MT-2w (16.6) < MT-1w (17.7) < MT-3w (18.9) < MT-4w (20.8). M⁻ has a catalysis effect on the energy barrier and the order is M⁻T-2w (14.4) < M⁻T-3w (15.2) < M⁻T-1w (16.3) < M⁻T-4w (16.8). The attachment of the M⁻ fragment slightly promotes the proton-transfer processes in some instances. The characterization of the proton-transfer processes is helpful to understand the genotoxicity of ZIF-8 during drug delivery applications.

Investigations on whether fragments from decomposed ZIF-8 would affect the intramolecular proton-transfer of thymine by DFT modeling.     

Biological effect of food additive titanium dioxide nanoparticles on intestine: an in vitro study

Titanium dioxide nanoparticles (TiO₂ NPs) are widely found in food‐related consumer products. Understanding the effect of TiO₂ NPs on the intestinal barrier and absorption is essential and vital for the safety assessment of orally administrated TiO₂ NPs. In this study, the cytotoxicity and translocation of two native TiO₂ NPs, and these two TiO₂ NPs pretreated with the digestion simulation fluid or bovine serum albumin were investigated in undifferentiated Caco‐2 cells, differentiated Caco‐2 cells and Caco‐2 monolayer. TiO₂ NPs with a concentration less than 200 µg ml^–1 did not induce any toxicity in differentiated cells and Caco‐2 monolayer after 24 h exposure. However, TiO₂ NPs pretreated with digestion simulation fluids at 200 µg ml^–1 inhibited the growth of undifferentiated Caco‐2 cells. Undifferentiated Caco‐2 cells swallowed native TiO₂ NPs easily, but not pretreated NPs, implying the protein coating on NPs impeded the cellular uptake. Compared with undifferentiated cells, differentiated ones possessed much lower uptake ability of these TiO₂ NPs. Similarly, the traverse of TiO₂ NPs through the Caco‐2 monolayer was also negligible. Therefore, we infer the possibility of TiO₂ NPs traversing through the intestine of animal or human after oral intake is quite low. This study provides valuable information for the risk assessment of TiO₂ NPs in food. Copyright © 2015 John Wiley & Sons, Ltd.     

Realigning Demand and Supply Side Incentives to Improve Primary Health Care Seeking in Rural China

China's recent and ambitious health care reform involves a shift from the reliance on markets to the reaffirmation of the central role of the state in the financing and provision of services. In collaboration with the Government of the Ningxia province, we examined the impact of two key features of the reform on health care utilisation using panel household data. The first policy change was a redesign of the rural insurance benefit package, with an emphasis on reorientating incentives away from inpatient towards outpatient care. The second policy change involved a shift from a fee‐for‐service payment method to a capitation budget with pay‐for‐performance amongst primary care providers. We find that the insurance intervention, in isolation, led to a 47% increase in the use of outpatient care at village clinics and greater intensity of treatment (e.g. injections). By contrast, the two interventions in combination showed no effect on health care use over and above that generated by the redesign of the insurance benefit package. Copyright © 2014 John Wiley & Sons, Ltd.     

Strong,tough and mechanically self-recoverable poly(vinyl alcohol)/alginate dual-physical double-network hydrogels with large cross-link density contrast

Strong and tough poly(vinyl alcohol) (PVA)/alginate hydrogen-bonded-ionic dual-physical double-network (DN) hydrogels have been successfully prepared by a facile route of a freeze–thaw (25–25–25 °C) cycle followed by concentrated (1.0 mol L⁻¹ of) aqueous-Ca²⁺ immersion of PVA/Na alginate (SA) mixed aqueous solutions. It was found that, at mole ratios of the PVA- to SA repeat units of 20/1 to 80/1, the DN gels likely evolved a semi-interpenetrating polymer network (IPN) morphology of rigid alginate networks dispersed in while interlocking with ductile PVA network to accomplish DN synergy that gave their high strength and toughness, where the high alginate rigidity originated probably from its dense cross-link induced syneresis and dispersion along crosslink-defective voids to result in little internal stress concentration. Tentatively mechanistically, as the 20/1–80/1 DN gels were stretched steadily, their mechanical response was gradually differentiated into distinct synergistic states: the sparsely hydrogen-bonded PVA served as a ductile matrix to bear small fractions of the established stresses at its large elongations; whereas the densely ionically (i.e. Ca²⁺) cross-linked alginate functioned as a rigid skeleton to sustain the remaining larger stresses upon its smaller local strains. Promisingly, this ductile-rigid matrix-skeleton synergistic mechanism of semi-IPN morphology may be universally extended to all A/B DN hydrogels of large A–B rigidity (or cross-link density) contrast, whether the cross-link nature of network(s) A or B is covalent, ionic, hydrogen bonded or van der Waals interacted. The strong and tough DN gels also displayed satisfactory self-recovery of viscoelastic behaviour, in that their Young''s modulus and dissipated energy in the uniaxial tensile mode and dynamic storage and loss moduli in the oscillatory shear mode all recovered significantly from non-linear viscoelastic regimes despite different degrees of failure to revert to (quasi)linear viscoelasticity.

Intermediate compositions enable synergised, strong-and-tough dual-physical double-network hydrogels of dispersion-induced rigid, ionic alginate-networks interlocking with global ductile, hydrogen-bonded poly(vinyl alcohol)-network.     

Retracted Article: High performance liquid chromatography coupled with high resolution mass spectrometry-based characterization of lipidomic responses from rats with kidney injuries

Metabolism of lipids is essential for the regulation of a variety of key cellular functions. Recent advances in high performance liquid chromatography coupled with high resolution mass spectrometry have expanded our knowledge of lipid metabolism in diseases. Currently, sepsis is one of the most important public health problems all over the world, which is a serious systemic inflammatory syndrome leading to infection by various agents or trauma and subsequently to a multiple organ dysfunction response. However, little is known about the lipids affected by sepsis and their roles in kidney injuries. In this study, we present targeted and non-targeted lipidomics strategies to discover the lipid metabolism variation in serum in rats with sepsis-induced kidney injuries. Liquid chromatography (LC) coupled with mass spectrometry (MS) and multivariate data analysis were used to obtain the global lipid metabolic profiles. In addition, biochemical parameters and histopathological examination results for the kidney were analyzed to support the pathological changes during sepsis-induced kidney injury. The identification of ten proposed lipids and five relevant pathways will promote a better understanding of lipid profile alterations in kidney injury. The results suggested that lipid metabolism in sepsis-induced kidney injury had changed significantly and contribute by offering potential targets for clinical diagnosis and therapy in the future, which would be worth further studies to broaden the applications of high performance liquid chromatography coupled with high resolution mass spectrometry in the study of lipid metabolism.

In this study, we present targeted and non-targeted lipidomics strategies to discover the lipid metabolism variation in serum in rats with sepsis-induced kidney injuries.     

Free-standing polydopamine films generated in the presence of different metallic ions: the comparison of reaction process and film properties

Polydopamine is widely used in surface modification, nanofiltration, photonic devices and drug delivery. The formation mechanism and properties of polydopamine are modified by the experimental conditions. Herein we demonstrated a comparison study of free-standing polydopamine films generated at the air–solution interface and their corresponding nanoparticles in solutions, in the presence of various metallic cations, Na⁺, Ca²⁺, Mg²⁺ and Co²⁺. Adding metallic ions influenced the intermediates in dopamine polymerization, and in turn the morphology and properties of the produced free-standing polydopamine films. Moreover, we observed that the polymerization process accompanying the stratification determines the formation of free-standing films at the air–solution interface: the fast polymerization of dopamine in a Co²⁺ environment leads to a rugged film surface and porous film body, whereas the comparatively slow polymerization of dopamine under conditions of other metallic ions results in a smooth and solid film. In addition, the water contact angles of the upper and lower surface of the polydopamine films were different. This investigation enriches our knowledge of dopamine polymerization in different environments, which is particularly useful for further application of free-standing polydopamine films.

Different stratification processes lead to different morphologies of films generated with various cations.     

Novel SrTiO3/NaTaO3 and visible-light-driven SrTiO3/NaTaO3:N nano-heterojunctions with high interface-lattice matching for efficient photocatalytic removal of organic dye

SrTiO₃/NaTaO₃ (STO/NTO) heterojunction photocatalysts were successfully constructed by decorating NaTaO₃ nanocubes with SrTiO₃ nanoparticles via a hydrothermal method. The structure of the perovskites NaTaO₃ and SrTiO₃ bear some resemblance to each other, which increases the interface lattice match for promoting the migration of photogenerated carriers between the STO/NTO interfaces. In comparison to pristine NaTaO₃ and SrTiO₃ samples, the STO/NTO composites exhibited remarkably improved capacity for the degradation of rhodamine B (RhB) under ultraviolet (UV) light (λ < 400 nm) irradiation. Furthermore, the partial replacement of O²⁻ by N³⁻ in the TaO ₆ octahedron narrowed the band gap of NaTaO₃, which significantly enhanced the photocatalytic performance of the SrTiO₃/NaTaO₃:N (STO/NTON) heterojunction under visible light (λ > 400 nm). Finally, the possible band structures of the STO/NTO and STO/NTON photocatalysts were proposed, which indicated that an n–n type heterojunction was constructed with a staggered gap for fast separation of photogenerated electron–hole pairs.

Novel SrTiO₃/NaTaO₃ and visible-light-driven SrTiO₃/NaTaO₃:N nano-heterojunctions with high interface–lattice match were synthesized for efficient photocatalytic removal of organic dye.     

An antibacterial collagen membrane crosslinked by the inclusion complex of β-cyclodextrin dialdehyde and ofloxacin for bacterial keratitis

Infectious keratitis is one of the leading causes of blindness in the world, especially in developing countries. Corneal transplant surgery is a feasible treatment for bacterial keratitis when drug therapy cannot be effective. However, the amount of corneal donors is far from requirements of clinical treatment and thus, the prognosis of bacterial keratitis is not satisfactory. In this study, we developed a novel antibacterial corneal repair material (β-CD-DA/OFLX-Col) for bacterial keratitis. The inclusion complex of β-cyclodextrin dialdehyde (β-CD-DA) with ofloxacin formed by host–guest interaction was used as both a drug vector and a crosslinker for further reaction with the amino groups on lysine of collagen chains. Physical properties, cytocompatibility, and antibacterial property of β-CD-DA/OFLX-Col film were characterized. The results indicated that the film was mainly transparent and possessed superior mechanical properties. Moreover, human corneal epithelial cells could adhere to the film and proliferate normally, indicating that the β-CD-DA/OFLX-Col film was non-cytotoxic and had good biocompatibility. Most importantly, the β-CD-DA/OFLX-Col film exhibited prominent antibacterial effects against E. coli and S. aureus in vitro, which could minimize the risks of infection. The prepared β-CD-DA/OFLX-Col film could greatly increase bioavailability of drugs and reduce toxic side effects, thus displaying great potential in bacterial keratitis treatment.

The synthesis of antibacterial collagen membrane crosslinked by the inclusion complex of β-cyclodextrin dialdehyde and ofloxacin.     

新型节能实用熏蒸床的研制

本文阐述了一种节能实用的熏蒸床的研制过程。该熏蒸床主要由床体和舱体组成;床面下设有舱体,舱体内设有蒸汽输入口,用于连接蒸汽分流盘管,舱体外设有进气阀门和排液阀门;床面下方设有蒸汽锅,蒸汽锅和阀门之间通过管道连接。该熏蒸床容积缩小为原来的1/3,节电节能,蒸汽效果迅速;熏蒸锅电汽分离,安全可靠;蒸汽输出末端设有蒸汽分流盘管,便于冷凝水收集;具有3个熏蒸舱,可根据舱体的不同物理位置自动区分熏蒸温度;拆卸方便,故障率低。临床应用证实其应用效果良好,值得临床推广。