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Minimizing energy consumption, the amount of chemicals used, and secondary wastes is key to achieving a techno-economic approach for recycling spent lithium-ion batteries (LIBs). Herein, we report a vapor thermal reduction approach to converting lithium transition metal oxides (LTMOs) to water-insoluble TMOs and water-soluble Li salts with markedly reduced water and chemical use, and temperature. Compared with the hydrothermal process, the water vapor approach reduces the usage of water and ammonium salts, making the selective extraction happen at

Rational design of hierarchical photocatalysts for dye degradation and hydrogen production has been believed as a wise selection for pollution control and energy solution. Herein, we present the design and synthesis of Fe3O4@SiO2@ZnO–Ag core shell microstructures with different ZnO loading amounts. The structure, morphology, composition, optical and magnetic properties of the as-synthesized samples were investigated by several characterization techniques. Photocatalytic degradation of rhodamine B (RhB) and hydrogen evolution under UV light were selected to assess the impact of ZnO loading amount on photocatalytic activities. Photocatalytic results reveal that Fe3O4@SiO2@ZnO–Ag with 15.14 wt% ZnO loading amount shows the best photocatalytic property. The RhB degradation efficiency of this sample was 98.1% after 100 min of UV light exposure. Additionally, the hydrogen evolution rate of this sample was 183 μmol h−1 under UV light illumination. It is also worth noting that these core shell microspheres were endowed with outstanding magnetic response, excellent photocatalytic reusability and chemical stability. The core shell photocatalysts can maintain high efficiency after five-cycles of RhB photocatalytic degradation run. Such features mentioned above made heterostructure Fe3O4@SiO2@ZnO–Ag photocatalysts promising candidates in practical use for environmental and energy challenges.

Oxygen reduction reaction (ORR) is an important cathode reaction in fuel cells and metal-air batteries. Composites of transition-metal sulfides (TMSs) and nitrogen-doped carbon (NC) are promising alternative ORR catalysts because of their high catalytic activity. However, the agglomeration of TMS particles limits practical applications. Here, a confinement catalyst composed of Co9S8@NC with a flower-like morphology was derived from metanilic intercalated Co(OH)2 through interlayer-confined carbonation accompanied with host-layer sulfidation. The surface of the Co9S8 particles is covered with a few layers of nitrogen-doped graphene, which can prevent the Co9S8 particles from agglomeration and also produce catalytic activity affected by internal Co9S8. Thus, the Co9S8@NC material achieves excellent ORR performance with a half-wave potential of 0.861 VRHE. In addition, an oxide layer on the surface of Co9S8@NC is fabricated shortly after the ORR starts. Further tests and density functional theory calculations indicated that this cobalt oxide layer can increase the electrochemically active area of Co9S8@NC as well as reduce the ORR energy barrier, thereby providing more catalytic active sites and enhancing the intrinsic catalytic activity, thus achieving a self-activation effect during the electrochemical reaction process.

Objective: Acute fatty liver of pregnancy(AFLP) is a rare but very urgent obstetric disease in clinical. It is a common cause of liver failure in pregnancy and often needs to be admitted to the department of critical care medicine because of the rapid development of acute hepatic dysfunction and severe acute renal dysfunction. The etiology and pathogenesis of this disorder is not very clear although there have been many studies on it before. Meanwhile, the relatively high mortality requires a better recognition in order to better guide clinical decision making. Our previous multicentre retrospective study on AFLP demonstrated that total bilirubin and serum creatinine were independent risk factors for perinatal maternal mortality. And we aim to further assess maternal outcomes and risk factors in AFLP patients treated without plasma exchange or renal replacement therapy based on previous data we collected.Methods: Retrospective cohort study of 133 hospitalized patients with AFLP was collected from four Chinese tertiary hospitals during the period between January 2009 and April 2014. One hundred thirty three patients were divided into two subgroups containing patients treated without plasma exchange (PE) or renal replacement therapy (CRT) and patients treated with PE or/and CRT. Logistic regression was used to analyze independent risk factors for maternal mortality of AFLP treated without PE or CRT.Results: The maternal mortality rate was 12.0% in subgroup of patients treated without PE or CRT. And in subgroup of patients treated with PE or/and CRT, the maternal mortality rate was 26.8%. Independent risk factors for maternal mortality of AFLP treated without PE or CRT were direct bilirubin (OR = 1.012; 95% CI, 1.002-1.022) and serum creatinine (OR = 1.022; 95% CI, 1.007-1.036).Conclusion: Although less liver and kidney damage in AFLP treated without PE or CRT, direct bilirubin and serum creatinine remained to be independent risk factors for maternal mortality. Thus, the level of bilirubin and serum creatinine might not be necessary for AFLP to decide whether to give plasma exchange or dialysis treatment.

An ammonium chloride roasting approach can convert lithium metal oxides to water-soluble lithium and transition metal chlorides at 300 °C, promising an energy-efficient and environmentally benign w...

A n-BuLi triggered practical amination protocol of methoxy pyridine derivatives with aliphatic amines was developed. The reaction could finish in 30 min for primary amines and 10 min for secondary ...

A mild amination protocol of N-heteroaryl alkyl ethers with various amines is described. This transformation is achieved by utilizing simple and readily available base as promoter via C-O bond cleavage, offering a new amination strategy to access several anticancer-active compounds. This work is highlighted by the excellent functional group compatibility, scalability, wide substrate scope, and easy derivatization of a variety of drugs.

Context. Zishen Jiangtang Pill (ZJP) is a Chinese herbal compound, which has a positive therapeutic effect on diabetic osteoporosis (DOP) by regulating glucose metabolism and bone metabolism. However, its regulatory role and mechanism are still unclear. Objective. To explore the effect and mechanism of ZJP on DOP rats by proteomic analysis. Materials and Methods. After the establishment of diabetes model by Streptozocin (STZ, 60 mg/kg), 40 Wistar rats were equally divided into normal group, model group (diabetic rats), high-dose group (3.0 g/kg/d ZJP), and low-dose group (1.5 g/kg/d ZJP) and received treatment for 3 months. Histological changes in bone and pancreas tissues were observed by hematoxylin and eosin staining, electron microscopy, and immunofluorescence. Proteomic and bioinformatic analyses were performed to identify the differentially expressed proteins. The fingerprint and active ingredients of ZJP were identified via high-performance liquid chromatography (HPLC). Results. Compared with the model group, ZJP could rescue the weight, fasting blood glucose, and fasting insulin of rats in both high-dose and low-dose group. ZJP could also improve the microstructures of pancreatic islet cells, bone mass, and trabecular and marrow cavities in DOP rats. Bioinformatic analysis suggested that ZJP might influence DOP via multiple pathways, mainly including ribosomes, vitamin digestion and absorption, and fat digestion and absorption. The primary active ingredients, including notoginsenoside R1, ginsenoside Rg1, ginsenoside Re, icariin, and ginsenoside Rb1, were detected. Conclusion. ZJP could significantly improve the histomorphology and ultrastructure of bone and islets tissues and might serve as an effective alternative medicine for the treatment of DOP.

Highlights • Acrolein induced structural changes through the cross-linking of BLG. • The IgE binding capacity of BLG was reduced upon acrolein treatment. • Stimulation with acrolein-treated BLG decreased RBL-2H3 cells degranulation rates. • BLG-specific IgE/IgG1, histamine and mMCP-1 levels were reduced in mice model. • Structural changes resulted in reduction of BLG allergenicity by lipid peroxidation., β-lactoglobulin (BLG) is a major allergen of milk. Since lipid peroxidation such as acrolein commonly exists during milk processing, it is necessary to evaluate its influence on BLG structure and potential allergenicity. The structure of acrolein-treated BLG was detected using SDS-PAGE, fluorescence, ultraviolet spectrum (UV), circular dichroism (CD) and LC-MS-MS, and the potential allergenicity was assessed by in vitro and in vivo assays. Results showed that acrolein could cause structural changes by BLG aggregation, which decreased the IgE binding capacity. Further, the release of mediators and cytokines decreased with acrolein treatment in RBL-2H3 cells. Mice showed lower allergenicity by the levels of BLG-specific antibody and the release of histamine and mMCP-1. These results explained that acrolein-induced BLG aggregation could damage the allergic epitopes and decrease the allergenicity of BLG in milk. The study will provide a new aspect to explore the natural phenomenon of allergen changes during food processing.

Waste polyethylene terephthalate (PET) and reclaimed asphalt pavement (RAP) represent two categories of waste materials that are currently enduring major recycling efforts around the world. This st...

The promotion effect of O2 on the dissociative adsorption of H2O to UO2 surface is studied by first-principles method within generalized gradient approximation formalism corrected by on-site Coulomb interaction. Investigations on all UO2 low index surfaces indicate that U-terminate (001) surface is the highest energy surface. For the adsorption of O2 and H2O on the U-terminate UO2(001) surface, all O2 molecules dissociate spontaneously while H2O molecules only dissociate incompletely in some specific initial configurations. The results of co-adsorption demonstrate the promotion effect of O2 on the dissociative adsorption of H2O, and two different promotion mechanisms are studied detailedly.

In terms of the reaction of CO2 reduction to CO with hydrogen, CO2 conversion is very low at low temperature due to the limitation of thermodynamic equilibrium (TE). To overcome this limitation, plasma catalytic reduction of CO2 to CO in a catalyst-filled dielectric barrier discharge (DBD) reactor is studied. An enhanced effect of plasma on the reaction over Au/CeO2 catalysts is observed. For both the conventionally catalytic (CC) and plasma catalytic (PC, Pin = 15 W) reactions under conditions of 400 °C, H2/CO2 = 1, 200 SCCM, GHSV = 12,000 mL•g−1cat•h−1, CO2 conversions over Au/CeO2 reach 15.4% and 25.5% due to the presence of Au, respectively, however, those over CeO2 are extremely low and negligible. Moreover, CO2 conversion over Au/CeO2 in the PC reaction exceeds 22.4% of the TE conversion. Surface intermediate species formed on the catalyst samples during the reactions are determined by in-situ temperature-programmed decomposition (TPD) technique. Interestingly, it disclosed that in the PC reaction, the formation of formate intermediate is enhanced by plasma, and the acceleration by plasma in the decomposition of formate species is much greater than that in the formation of formate species on Au/CeO2. Enhancement factor is introduced to quantify the enhanced effect of plasma. Lower reactor temperature, higher gas hourly space velocity (GHSV), and lower molar ratio of H2/CO2 would be associated with larger enhancement factor.

CO 2 selective reduction to CO with H 2 over a CeO 2 -supported nano-Au catalyst at atmospheric pressure was investigated. A high CO 2 conversion, approaching the thermodynamic equilibrium value, and nearly 100% CO selectivity were obtained. The surface formate intermediates generated during the reverse water-gas shift reaction at 400℃ were identified using in situ diffuse-reflectance infrared Fourier-transform spectroscopy. The formate consumption to give CO and H 2 O, determined using mass spectrometry, indicated that the reaction proceeded via an associative formate mechanism; this contributes to the high Au/CeO 2 catalytic activity at low temperatures.

Intracerebral hemorrhage (ICH) is a common neurological condition associated with high disability and mortality. Alterations in protein ubiquitination have emerged as a key mechanism in the pathogenesis of neurological diseases. Here, we investigated the effects of the E3 ubiquitin ligase ring finger protein 34 (RNF34) on neurological deficits and brain injury in ICH mice. An ICH model was established via intracerebral injection of autologous blood into wild-type and RNF34 transgenic mice. Brain injury, neurological function, neuronal activity, and oxidative stress levels were measured, respectively. The underlying mechanisms were explored by molecular and cellular approaches. Our results showed that RNF34 overexpression in mice significantly aggravated the ICH-induced memory impairment, brain edema, infarction, hematoma volume, and loss of neuronal activity. RNF34 and oxidative stress levels gradually increased from 6 to 48 h after the ICH challenge and were positively correlated. The ICH-induced increase in intracellular ROS, superoxide anion, and mROS generation and the decrease in adenosine triphosphate production were exacerbated in RNF34 transgenic mice, but NADPH oxidase activity was unaffected. Moreover, RNF34 upregulation potentiated the ICH-induced decrease in PGC-1α, UCP2, and MnSOD expressions. RNF34 interacted with PGC-1α and targeted it for ubiquitin-dependent degradation. This study reveals that RNF34 exacerbates neurological deficits and brain injury by facilitating PGC-1α protein degradation and promoting mitochondrial dysfunction-mediated oxidative stress.

The present study aimed to investigate the role of microRNA-146a (miR-146a) in intracerebral hemorrhage (ICH), and to further assess its underlying mechanism. An ICH rat model was established in the current study and 1 h following ICH induction, rats were treated with or without an miR-146a mimic. A total of 3 days following ICH induction, rat neurological score, brain water content and neuronal apoptosis were measured via flow cytometry. Levels of pro-inflammatory cytokines tumor necrosis factor-α and interleukin-1β were detected via ELISA and certain biomarkers of oxidative stress, including malondialdehyde, superoxide dismutase and glutathione peroxidase, were also determined in current study. The expression of genes and proteins were detected in current study via reverse transcription-quantitative polymerase chain reaction and western blotting, respectively. MicroRNA.org software and a dual luciferase reporter assay were used to confirm the association between miR-146a and TRAF6. The results of the current study revealed that miR-146a was significantly downregulated in ICH rats, and its overexpression reduced neurological damage and brain edema, as evidenced by decreased neurological scores and brain water content. Results from further analyses demonstrated that the overexpression of miR-146a inhibited neuronal apoptosis, reduced pro-inflammatory cytokine production and prevented oxidative stress in ICH rats. In addition, it was revealed that the upregulation of miR-146a repressed the TRAF6/NF-κB pathway in the brain tissue of ICH rats. TRAF6 was also determined to be a target of miR-146a. In conclusion, these data indicated that miR-146a protects against ICH by inhibiting inflammation and oxidative stress.

To evaluate the roles of climate and hydrology in continental-scale silicate weathering, we applied Li isotopes to the Yellow River and systematically investigated seasonal Li flux, Li isotopic compositions and potential sources. We collected samples from the middle reaches of the Yellow River weekly over the full hydrological year of 2013. We find that the dissolved Li is mainly derived from silicates and evaporites in the arid to semi-arid Yellow River basin. Silicate weathering of loess during the monsoonal season dominates the Li flux in the middle reaches of the Yellow River, with a positive relationship between dissolved Li flux and physical erosion rate. Evaporite contribution for riverine Li was relatively constant in the middle reaches of the Yellow River but slightly increased after the storm event, with an average proportion of ∼25%, which might represent the proportion of evaporite contribution to global oceans. Seasonal variations in the riverine Li isotopic compositions are dominantly controlled by temperature with a fractionation gradient as −0.182‰ per °C over the full year with deviations likely driven by re-dissolution of suspended particulate matter, extreme hydrological events, and groundwater contribution. Temperature dependent δ7Li value variation of river water inputted into oceans indicates that Cenozoic climate cooling itself may be able to explain ∼2‰ of the 9‰ rise of Cenozoic seawater δ7Li value (Misra and Froelich, 2012). The seasonal variation in riverine Li isotopes highlights that erosion and weathering of loess may provide valuable clues on secular chemical weathering and seawater δ7Li variation spanning a range of time scales.

The search for new inorganic electrides has attracted significant attention due to their potential applications in transparent conductors, battery electrodes, electron emitters, as well as catalysts for chemical synthesis. However, only a few inorganic electrides have been successfully synthesized thus far, limiting the variety of electride examples. Here, we show the stabilization of inorganic electrides in the Ti-rich Ti–O system through first-principles calculations in conjunction with swarm-intelligence-based CALYPSO method for structure prediction. Besides the known Ti-rich stoichiometries of Ti2O, Ti3O, and Ti6O, two hitherto unknown Ti4O and Ti5O stoichiometries are predicted to be thermodynamically stable at certain pressure conditions. We found that these Ti-rich Ti–O compounds are primarily zero-dimensional electrides with excess electrons confined in the atom-sized lattice voids or between the cationic layers playing the role as anions. The underlying mechanism behind the stabilization of electrides has been rationalized in terms of the excess electrons provided by Ti atoms and their accommodation of excess electrons by multiple cavities and layered atomic packings. The present results provide a viable direction for searching for practical electrides in the technically important Ti–O system. Computer simulations predict that compounds made of oxygen and titanium atoms form cages that can host electrons in their interstices. A team led by Hanyu Liu and Yanming Ma from Jilin University, China, have investigated the possibility for materials belonging to the family of titanium dioxide, a pigment used in paints and sunscreens, to behave as electrides, materials in which electrons resemble larger negatively charged atoms in the way in which they localize and interact with the surrounding atomic structure. Their calculations show that this occurs if the amount of titanium atoms in the material exceeds that of oxygen atoms by at least a factor of 2, which allows the formation of larger cages in which electrons can be confined. The synthesis of these materials will allow to assess their significance for catalysis or other applications.

Producing methanol from coke oven gas (COG) is one of the important applications of COG. Removal of sulfur from COG is a key step of this process. Conversion and reaction kinetics over a commercial Fe−Mo/Al2O3 catalyst (T-202) were studied in a continuous flow fixed bed reactor under pressures of 1.6−2.8 MPa, space time of 1.32−3.55 s and temperatures of 240−360 °C. Though the COG contains about 0.6 mol/mol H2, hydrogenation of CO and CO2 is not significant on this catalyst. The conversions of unsaturated hydrocarbons depend on their molecular structures. Diolefins and alkynes can be completely hydrogenated even at relatively low temperature and pressure. Olefins, in contrast, can only be progressively hydrogenated with increasing temperature and pressure. The hydrodesulfurization (HDS) of CS2 on this catalyst is easy. Complete conversion of CS2 was observed in the whole range of the conditions used in this work. The original COS in the COG can also be easily converted to a low level. However, its complete HDS is difficult due to the relatively high concentration of CO in the COG and due to the limitation of thermodynamics. H2S can react with unsaturated hydrocarbons to form ethyl mercaptan and thiophene, which are then progressively hydrodesulfurized with increasing temperature and pressure. Based on the experimental observations, reaction kinetic models for the conversion of ethylene and sulfur-containing compounds were proposed; the values of the parameters in the models were obtained by regression of the experimental data.

The operating temperature determines the energy consumption and lithium extraction rate of a pyrometallurgical process. This paper aims to employ a molten ammonium sulfate ((NH4)2SO4) assisted roasting approach to recovering and regenerating LiCoO2 from spent lithium-ion batteries (LIBs) at 400 °C. First, cathode materials from the spent LIBs are converted to CoSO4 and Li2SO4 via a sulfation roasting approach. Both recovery rates of Li and Co reach over 98% at 400 °C for 2h and at an (NH4)2SO4/(cathode materials) mass ratio of 4:1 in Ar atmosphere. Then, the obtained Co(OH)2 and Li2CO3 are used to regenerate LiCoO2 that delivers a specific capacity of over 154 mAh g−1 at 1C with capacity retention of 94% after 100 cycles. Overall, the molten (NH4)2SO4 assisted roasting approach reduces the operating temperature to 400 °C while maintaining a high extraction rate of over 98% for both Li and Co, promising an energy-efficient approach to recovering various cathode materials from spent LIBs.

Cancers are deadly diseases. The general mystery of carcinogenesis, primary and acquired drug resistance and distant organ metastasis are still puzzles to be solved. Long noncoding RNAs (lncRNAs) are receiving more and more attention in recent years since their roles in transcriptional regulation have been unveiled. Detailed functional annotations of lncRNAs have showed that their regulatory roles are largely determined by their binding partners. LncRNAs directly bind to DNA, RNA and proteins and regulate gene expression at transcriptional, post-transcriptional and post-translational levels. Here we review the current understanding of molecular functions of lncRNAs, will emphasize on their binding partners and summarize their biological roles in cancer.

A reducing agent can reduce Co3+ to Co2+ in LiCoO2, thus increasing the leaching efficiency and extraction rate of Co-based cathode materials from spent lithium-ion batteries (LIBs). Herein, ethanol was employed as the reducing agent to leach LiCoO2 obtained from LIBs in a sulfuric acid solution. The effects of operating temperatures (50–90 °C), dosage of ethanol (0-20 vol%), concentration of sulfuric acid (2–6 mol/L), and solid/liquid ratio (10–40 g/L) on the leaching efficiency of LiCoO2 were investigated. By adding 5 vol% ethanol in a 6 mol/L sulfuric acid solution at 90 °C, the extraction efficiency of Co and Li are both over 99%, meaning that ethanol can reduce Co3+ to Co2+ while the ethanol was oxidized to acetic acid. The dissolution of LiCoO2 obeys the residue layer diffusion control model. Although ethanol is a promising reducing agent, future efforts should pay to the management of the secondary wastewater. Overall, the ethanol can be used as a reducing agent to assist the leaching of cathode materials from spent LIBs.

Glaucoma is an optic neuropathy commonly associated with elevated intraocular pressure (IOP) resulting in progressive loss of retinal ganglion cells (RGCs) and optic nerve degeneration, leading to blindness. New therapeutic approaches that better preserve the visual field by promoting survival and health of RGCs are highly needed since RGC death occurs despite good IOP control in glaucoma patients. We have developed a novel approach to reliably induce chronic IOP elevation in mouse using a photopolymerizable biomatrix, hyaluronic acid glycidyl methacrylate. This is achieved by rapid in vivo crosslinking of the biomatrix at the iridocorneal angle by a flash of ultraviolet A (UVA) light to impede the aqueous outflow pathway with a controllable manner. Sustained IOP elevation was induced after a single manipulation and was maintained at ~45% above baseline for >4 weeks. Significant thinning of the inner retina and ~35% reduction in RGCs and axons was noted within one month of IOP elevation. Optic nerve degeneration showed positive correlation with cumulative IOP elevation. Activation of astrocytes and microglia appeared to be an early event in response to IOP elevation preceding detectable RGC and axon loss. Attenuated glial reactivity was noted at later stage where significant RGC/axon loss had occurred suggesting astrocytes and microglia may play different roles over the course of glaucomatous degeneration. This novel murine glaucoma model is reproducible and displays cellular changes that recapitulate several pathophysiological features of glaucoma.

SERS-active substrate is fabricated by cosputtering Ag and SiO2 onto two-dimensional polystyrene (PS) colloidal particle templates in a magnetron sputtering system. When Ag and SiO2 are cosputtered onto ordered PS templates, the SiO2-isolated Ag island (SiO2–Ag) nanocap arrays with nanogaps and nanoscaled surface roughness form on PS particles, in which “hot spots” are facilely engineered on three-dimensional nanostructures. The surface-enhanced Raman scattering (SERS) activities of the SiO2–Ag nanocap arrays vary nonmonotonically and depend on the film thickness and surface roughness strongly. Under the optimized conditions, the SERS signal intensity of 4-aminothiophenol (PATP) is employed to evaluate the SERS ability (4.41 × 105). The addition of SiO2 not only avoids photobleaching and background fluorescence but also decreases the oxidation rate of Ag and increases the stability of Ag particles. The results demonstrate the potential applications of this technique in reproducible SERS substrate.

Here we demonstrate that efficient piezoelectric nanoparticle-polymer composite materials can be optically printed into three-dimensional (3D) microstructures using digital projection printing. Piezoelectric polymers were fabricated by incorporating barium titanate (BaTiO3, BTO) nanoparticles into photoliable polymer solutions such as polyethylene glycol diacrylate and exposing to digital optical masks that could be dynamically altered to generate user-defined 3D microstructures. To enhance the mechanical-to-electrical conversion efficiency of the composites, the BTO nanoparticles were chemically modified with acrylate surface groups, which formed direct covalent linkages with the polymer matrix under light exposure. The composites with a 10% mass loading of the chemically modified BTO nanoparticles showed piezoelectric coefficients (d(33)) of ∼ 40 pC/N, which were over 10 times larger than composites synthesized with unmodified BTO nanoparticles and over 2 times larger than composites containing unmodified BTO nanoparticles and carbon nanotubes to boost mechanical stress transfer efficiencies. These results not only provide a tool for fabricating 3D piezoelectric polymers but lay the groundwork for creating highly efficient piezoelectric polymer materials via nanointerfacial tuning.

In this study, we use an aqueous solution synthesis method to prepare silver perrhenate powders and suspend them into a poly alpha olefin (PAO) base oil with polyoxyethylene octylphenyl ether. Four ball tests and ball-on-disk reciprocating mode are performed to determine how silver perrhenate performs tribologically as a lubricating additive over a wide range of temperatures. The physical and chemical properties, as well as the lubricating mechanisms of the silver perrhenate additive, are characterized via X-ray diffraction, scanning electron microscope, Fourier transformation infrared spectroscopy, Raman spectrum, and X-ray photoelectron spectroscopy. The four-ball test results demonstrate that the oil added with silver perrhenate additive is more effective than the base oil in reducing friction and improving wear resistance, and provides the best lubricating performance when at a concentration of 0.5 wt%. The reciprocating mode findings indicate that the hybrid lubricant exhibits distinctively better tribological properties than the base oil at high temperatures, and its low shear strength and chemical inertness allow for low friction at elevated temperatures. The resulting silver perrhenate layer that incorporates native superalloy oxides on the worn surface can provide lubrication by serving as a barrier that prevents direct contact between the rubbing surfaces at elevated temperatures.

The volatile compounds in Alaska pollock frame and Alaska pollock frame hydrolysates were analyzed by solid-phase microextraction and gas chromatography-mass spectrometry for identifying and comparing their flavor characteristics. The optimized SPME extraction conditions were 75 μm carboxen/polydimethyl siloxane fiber, adsorption time of 40 min, and extraction temperature of 65°C. Compared to Alaska pollock frame, Alaska pollock frame hydrolysates have more aromas detected and identified. Numerous volatile compounds were responsible for the overall aroma of Alaska pollock frame hydrolysates, such as 1-penten-3-ol, 2-penten-1-ol, ethyl acetate, methacrolein, 3-methylbutanal, hexanal, octanal, nonanal, 6-methyl-5-hepten-2-one, and so on. However, only a relatively small proportion showed similar composition. Although Alaska pollock frame hydrolysates was prepared by the same raw material, each Alaska pollock frame hydrolysate exhibited its individual flavor characteristics. Thus, the type of enzyme was prob...

Lipopolysaccharide (LPS)-induced oxidative stress is a main feature observed in the sepsis by increasing endothelial oxidative damage. Many studies have demonstrated that Ulinastatin (UTI) can inhibit pro-inflammatory proteases, decrease inflammatory cytokine levels and suppress oxidative stress. However, the potential molecular mechanism underlying UTI which exerts its antioxidant effect is not well understood. In this study, we aimed to investigate the effects of UTI on the LPS-induced oxidative stress and the underlying mechanisms using human umbilical vein endothelial cells (HUVECs). After oxidative stress induced By LPS in HUVECs, the cell viability and reactive oxygen species (ROS) in cytoplasm were measured. In addition, superoxide dismutase (SOD) and malondialdehyde (MDA) were examined. We found that LPS resulted in a profound elevation of ROS production and MDA levels. The decrease in Cu/Zn-SOD protein and increased in Mn-SOD protein were observed in a time- and dose-dependent manner. These responses were suppressed by an addition of UTI. The increase in c-Jun N-terminal kinases (JNK) phosphorylation by LPS in HUVECs was markedly blocked by UTI or JNK inhibitor SP600125. Our results suggest that UTI exerts its anti-oxidant effects by decreasing overproduction of ROS induced by LPS via suppressing JNK/c-Jun phosphorylation. Therefore UTI may play a protective role in vascular endothelial injury induced by oxidative stress such as sepsis. This study may provide insight into a possible molecular mechanism by which Ulinastatin inhibits LPS-induced oxidative stress.

BACKGROUND Autoimmune systemic lupus erythematosus (SLE) is associated with inflammatory activity and frequently causes complications in pregnant women. The aim of the current study was to investigate the serum levels of chemokines and cytokines (CKs) in SLE women during pregnancy and to examine the activation of toll-like receptor 4 (TLR-4) signaling in the deregulation of chemokines and CKs. METHODS Blood samples from pregnant women with or without SLE were assayed for the levels of CKs (interleukin (IL)-1β, IL-6, IL-8, and IFN-α), chemokines (IP-10 and RANTES) with enzyme-linked immunosorbent assay (ELISA) and were examined for toll like receptor (TLR)-2, -4, -7, -8 and -9. Then the peripheral blood mononuclear cells (PBMCs) from the SLE or normal pregnant women were treated with lipopolysaccharide (LPS) and were assayed for the CKs promotion. RESULTS It was demonstrated that there were higher serum concentrations of IL-1p, IL-8, IFN-t, and IP-10 (p < 0.05, p < 0.01 or p < 0.0001) in the SLE pregnant women than in the non-SLE pregnant women. Additionally, the TLR-4 at the mRNA level in the PBMCs was also significantly higher in the SLE pregnant women than in the non-SLE pregnant women (p < 0.05). Moreover, the upregulated IL-1β, IL-8, IFN-α or IP-10 was associated with the promoted TLR-4 level in PBMCs of those SLE patients. In addition, the PBMCs from the SLE pregnant women were more responsive to LPS stimulation. There was more promoted IL-1β, IL-8, or IFN-α in the PBMCs from the SLE pregnant women. CONCLUSIONS High levels of pro-inflammatory CKs and chemokines were promoted during pregnancy in women with SLE, possibly increasing their risk for pregnancy complications. In addition, the TLR4 signaling might play an important role in such CKs promotion.

A facile method to selectively synthesize nano-scaled Gd2O3 with different morphology such as nanosheres and nanorods has been developed in our report. The precursors GdOHCO3 can be prepared by a two-step hydrothermal process via homogeneous generation of hydroxide ions through the hydrolysis of urea, and the formation of different morphology structures were obtained under different reaction temperatures. After further heating treatment, a transformation from GdOHCO3 to cubic Gd2O3 takes place. The morphology and size of nano Gd2O3 strongly depend on that of the precursors GdOHCO3. The X-ray diffraction, transmission electron microscopy and scanning electron microscopy were employed to characterize the as-obtained low-dimensional nanostructures. And the effects of hydrothermal temperature, solvent and urea concentration on the morphologies of the products were also studied.

The influence of the activation conditions on the catalytic performance and microstructure of supported V–Mo oxides used for benzene oxidation to maleic anhydride has been investigated. To activate the catalysts, two sets of activation conditions were tested. In condition I, the catalysts were activated in an atmosphere of air and benzene, which was similar to the industrial practice. In condition II, the catalysts were pre-activated in an atmosphere consisting of the gas products produced by the decomposition of the freshly prepared catalysts during activation process. The activity and selectivity of the catalysts were evaluated on a bench scale reactor as well as on a pilot reactor. The catalysts activated by condition II at the appropriate temperature showed a better performance: the selectivity and yield of MA were nearly 80 and 100 wt%, respectively. They are 5 % higher than those of the catalyst activated by condition I. The catalysts were characterized in terms of several techniques including isotherm adsorption, TG-DTG, XRD, SEM, EDX and XPS. The characterization results indicated that the microstructures of the catalysts were significantly influenced by the activation conditions. Based on the above information, the better performance exhibited by the catalyst activated by condition II are analyzed.

The retention of lipoproteins in the arterial intima is an initial event in early atherosclerosis and occurs, in part, through interactions between negatively charged glycosaminoglycans (GAGs) and the positively charged residues of apolipoproteins. Smooth muscle cells (SMCs) which infiltrate into the lipoprotein-enriched intima have been observed to transform into lipid-laden foam cells. This phenotypic switch is associated with SMC acquisition of a macrophage-like capacity to phagocytose lipoproteins and/or of an adipocyte-like capacity to synthesize fatty acids de novo. The aim of the present work was to explore the impact of GAG identity on SMC foam cell formation using a scaffold environment intended to be mimetic of early atherosclerosis. In these studies, we focused on chondroitin sulfate C (CSC), dermatan sulfate (DS), and an intermediate molecular weight hyaluronan (HAIMW, ∼400 kDa), the levels and/or distribution of each of which are significantly altered in atherosclerosis. DS hydrogels were associated with greater SMC phagocytosis of apolipoprotein B than HAIMW gels. Similarly, only SMCs in DS constructs maintained increased expression of the adipocyte marker A-FABP relative to HAIMW gels over 35 days of culture. The increased SMC foam cell phenotype in DS hydrogels was reflected in a corresponding decrease in SMC myosin heavy chain expression in these constructs relative to HAIMW gels at day 35. In addition, this DS-associated increase in foam cell formation was mirrored in an increased SMC synthetic phenotype, as evidenced by greater levels of collagen type I and glucose 6-phosphate dehydrogenase in DS gels than in HAIMW gels. Combined, these results support the increasing body of literature that suggests a critical role for DS-bearing proteoglycans in early atherosclerosis.

Magnesium perrhenate used as a lubricating additive was prepared by an aqueous solution method in this paper, and was suspended in a base oil poly alpha olefin (PAO6) with the aid of surface active agents (SA). The thermal stability of the mixed oil with/without magnesium perrhenate and surface active agents was investigated by thermogravimetry testing. The influences of magnesium perrhenate as solid lubricating additive on the extreme pressure performance and the friction-reducing properties over a wide temperature range of the mixed lubricants were determined by four-ball tests and ball-on-disc frictional tests for the commercially available silicon nitride ball and a Ni-base superalloy frictional pair. The results revealed that the added magnesium perrhenate did not obviously affect the thermostability and oxidation resistance of the base oil. Meanwhile, it minimized the coefficients of friction and wear scar diameter to a certain extent in the four-ball experimental conditions. Ball-on-disc rubbing tests suggested the mixed oil had a similar lubricating performance to the base oil below the decomposition temperature point. The most significant advancement was the impressive antifriction improvement at the high temperature range, while the friction coefficients of the oil containing magnesium perrhenate compound were obviously below that of the base stock. This better tribological performance of the mixed lubricant was attributed to the native shear susceptible property and chemical stability of magnesium perrhenate under high temperature conditions, which could form an effective durable and stable antifriction layer with the oxides from the superalloy matrix, thereby decreasing the friction in the high-temperature environment.

Objective: Our aim was to investigate the correlation between free fatty acid (FFA) spectrum, blood stasis (BS) score, and macroangiopathy in type 2 diabetic patients with or without BS, as well as the possible relationship between BS and lipotoxicity. Methods: A total of 50 type 2 diabetes (T2D) patients with or without BS were enrolled from June to December 2014 in Shenzhen Traditional Chinese Medicine (TCM) Hospital, with 25 patients allocated to each of two groups. Basic information, BS score, blood glucose, blood lipids, etc., were measured for each patient. In addition, we tested the levels of interleukin (IL)-6, tumor necrosis factor α (TNF-α), and IL-18 with enzyme-linked immunosorbent assay. The macroangiopathy status of patients in the two groups was examined by color ultrasound and all factors related to BS scores were analyzed. Gas chromatography-mass spectrometry was used to explore the difference in the serum FFA spectra between the two different groups. In addition, the relationship between FFA spectra, BS scores, and macroangiopathy was analyzed. Results: BS scores, total cholesterol (TC), total triglyceride (TG), low-density lipoprotein cholesterol, IL-6, TNF-α, IL-18, carotid and femoral artery plaque, carotid intima-media thickness, carotid plaque area, and femoral artery plaque area were all significantly increased in T2D patients with BS syndrome (P < 0.05). A positive correlation was observed between age, duration of diabetes, carotid intima-media thickness, carotid plaque area, femoral artery plaque area, and BS score (P < 0.05). A total of 21 fatty acids were found in the serum, and total FFA (TFFA), saturated fatty acid (SFA), lauric acid (C12:0), palmitic acid (16:0), stearic acid (C18:0), arachidonic acid (C20:4n6), behenic acid (C22:0), and lignoceric acid (C24:0) scores were all found to contribute to the difference between FFA spectrums of the two groups; of the fatty acids, C12:0, C16:0, C18:0, C22:0, TFFA, and SFA positively correlated with BS scores as evaluated by Pearson's or Spearman's correlation analysis (P < 0.05). Only SFA entered the regression equation in the multiple linear regression analysis. C12:0, C16:0, C18:0, C20:4n6, TFFA, and SFA were positively correlated with carotid plaque area, whereas linoleic acid (C18:3n3), Cis-5, 8, 11, 14, and 17-eicosapentaenoic acids (C20:5n3) were negatively correlated (P < 0.05). C16:0 was positively correlated with the femoral artery plaque area and C18:3n3, cis-4, 7, 10, 13, 16, and 19-docosahexaenoic acids (C22:6) and nervonic acid were negatively correlated (P < 0.05). Conclusion: Serum FFA spectra were significantly different between T2D patients with BS and those without, and long-chain SFA made the greatest contribution. Serum FFA spectra were correlated with BS scores and diabetic macroangiopathy, which means that lipotoxicity and BS are correlated in T2D.

The morphological differences of chitosan (CS) in the hydroxyapatite (HA)/CS nanocomposites were investigated in detailed, which were prepared via in situ hydrothermal precipitation. The results show that the obtained nanocomposites have excellent crystallinity and the crystal has excellent ordered structure, which is important to the composites performances in the biomedical application. Moreover, the CS arrangement and crystallinity in the composites greatly depend on the hydrothermal temperature and the pH value of precipitating agent. The temperature ranging from 373 to 413K and pH value of precipitating agent ranging from 12 to 14 were favorable to the crystallization and oriented growth of CS molecules in the composites. The CS crystals with better arrangement are assembled in the order of layer-by-layer in these composites.

A combination of X-ray powder diffraction, thermogravimetric analysis, diffuse reflection infrared Fourier transform, and 31P magic-angle spinning nuclear magnetic resonance techniques with density function computation was used to elucidate the products and mechanism of the reactions among silica, H3PO4, and NaH2PO4 during the preparation of silica supported H3PO4 and NaH2PO4 catalysts. The spectral test results indicate that besides polyphosphoric acid, silicon phosphates on silica supported H3PO4 are also formed. On silica supported NaH2PO4 only sodium polyphosphates are present. Density functional theory (DFT) simulations indicate that in the initial stage, reaction of H3PO4 with silanol groups on the silica support is more favorable than that between H3PO4 itself. In contrast, dimerization and trimerization of NaH2PO4 are predicted to be the predominant initial reactions for the silica supported NaH2PO4 catalyst.

A novel two-step foaming process has been developed to prepare the porous titanium implant. By using H2O2 and stearic acid as foaming reagent ordinally, a foamed structure with an open, interconnected pore morphology was obtained. The mechanical property was determined by compressive test. In vitro study was conducted to evaluate the ability of the porous titanium to support the growth and differentiation of Human osteosarcoma cell line MG63. The results show that the porous titanium has better interconnection compared to that obtained by traditional slurry foaming and its compressive strength and Young’s modulus were approximate 23.6 MPa and 2.1 GPa, respectively. Cell culture experiment results indicate that the porous titanium has good biocompatibility and acid-alkali treatment facilitates the adherence and proliferation of cells.

BaTiO3 nanocrystals were synthesized by sol-gel method using barium acetate (Ba(CH3COO)2) and tetra-butyl titanate (Ti(OC4H9)4) as raw materials. Xerogel precursors and products were characterized by means of thermogravimetric/differential scanning calorimetry (TG/DSC), X-ray diffraction (XRD) and transmission electron microscope (TEM). The influence of the calcination temperature and duration on the lattice constant, the lattice distortion, and the grain size of BaTiO3 nanocrystals was discussed based on the XRD results. The grain growth kinetics of BaTiO3 nanocrystals during the calcination process were simulated with a conventional grain growth model which only takes into account diffusion, and an isothermal model proposed by Qu and Song, which takes into account both diffusion and surface reactions. Using these models, the pre-exponential factor and the activation energy of the rate constant were estimated. The simulation results indicate that the isothermal model is superior to the conventional one in describing the grain growth process, implying that both diffusion and surface reactions play important roles in the grain growth process.

In the present study, ZrO2 was added into the injectable calcium phosphate cements (CPCs) to improve their mechanical strength. Different mass fractions of ZrO2 (5 %, 10 %, 15 %, 20%) were mixed with the powder components consisted of tricalcium phosphate (α-TCP) and hydroxyapatite (HA). Then formed the paste via adding the liquid component consisted of citric acid. The compressive strength, the injectability, the initial setting time and finial time of CPC were measured, respectively. X-ray diffraction (XRD) was employed to analyse the phase of as-prepared CPC. Scanning Electron Microscope (SEM) and Energy dispersive spertrum (EDS) were used to observe the morphology and indicate the element components of CPC. The compressive strength of ZrO2-CPC was higher than that of CPC without added ZrO2. The compressive strength got the maximal when the mass fraction of ZrO2 was 15%. It had no effect on the injectability with adding ZrO2, which were 89 % to 92 %. It had a slight down-regulation of the initial and final setting time with adding ZrO2. SEM showed that there was amounts needle-like substance in CPC, which might be related to the improvement of compressive strength of CPC. XRD showed that there were HA, a few of α-TCP and ZrO2 diffraction peaks in CPCs. The present results indicate that it is feasible to improve the compressive strength of injectable CPC via adding ZrO2.

In this work, triethyl phosphate (TEP) was used to bioactivating titanium. Titanium plates grafted with TEP were immersed in a two times concentrated simulated body fluid (2SBF) to investigate deposition of hydoxyapatite (HA) on the surface. A phosphate buffer solution (PBS) with bovine serum albumin (BSA) was used to evaluate adsorption of protein on the grafted titanium surface. The morphology, component and structure of samples were examined by scanning electronic microscopy, attenuated total reflection Fourier transform infrared spectroscopy and X-ray diffraction respectively. The concentration change of BSA in adsorption test was examined with the ultraviolet-visible absorption spectra (UV). The analyses showed that TEP grafted onto the titanium surface. In 2SBF, calcium and phosphate ions deposited spontaneously onto the grafted titanium surface and formed a HA coating with a network-like microporous structure after being immersed for 3 days. The coating consisted of HA particles with 180-265nm in thickness and 72-85nm in width. The diameter of the micropores was about 200nm. The HA coating appeared better uniformity than that on the modified titanium using phosphoric acid. BSA rapidly adsorbed onto the grafted titanium surface at first half an hour and then the adsorption quantity almost kept constant. These results indicate that TEP grafting is an effective approach to modify bioactivity of titanium.

Three 3-substituted derivatives of quercetin were synthesized in 10-80% overall yields. Their structures were characterized by 1 HNMR. Three target compounds (4a~4c) have not been reported before. The results showed that: pre-treated of PC-12 cells with, cell survival rate was higher than that of quercetin. In this project, the oxidative damage model of PC-12 cells was established and the antioxidant activities of three newly synthesized quercetin derivatives were evaluated. Among them, compound 4b (30μM) showed the highest antioxidant activity against H2O2. Cell viability in pre-treated with or without compound 4b (30μM) were 53.05% and 10.31%, higher than that of quercetin (47.22%).

The titanium surfaces containing calcium, phosphate ions and the carbonate apatite were characterized. The effect of surface chemistry on the initial rabbit osteoblast response on these surfaces was investigated. The cell count and alkaline phosphatase (ALP) specific activity assay were used for biochemical analyses. Scanning electron microscopy was used for morphology observation and in particular X-ray photoelectron spectroscopy (XPS) for surface chemistry characterization. The number of cells adhering to the apatite coating surface was the maximum, the number of cells on the surface containing calcium without phosphate ions was higher than that containing phosphate without calcium, and the number on the unmodified titanium surface was the least. The osteoblasts cultured on the apatite surface exhibited the highest ALP specific activity, next were the ones on the surface containing solely calcium, the lowest were on the unmodified titanium surface. On the substrate surfaces removed of adhered cells, the order of nitrogen amounts detected by XPS was consistent with ones of ALP specific activity and cell number, except for the unmodified titanium surface. For the substrate surfaces removed of adhered osteoblasts, XPS analysis showed that calcium and phosphorous amounts decreased during cell adhesion. After cell culture the Ca2p binding energy (BE) values for apatite coating and the surface containing solely calcium were similar to those of the two surfaces adsorbed bovine serum albumin (BSA). The P2p BE values for the surfaces containing phosphate ions, including the apatite coating and the surface containing solely phosphate ions, showed the same change. But after cell culture the decrease of the P2p BE value for the coating surface was larger than the one for the surface containing solely phosphate ions. Considering the bovine serum albumin adsorption on the same samples, these results indicated that calcium ions on titanium surfaces play a more important role than phosphate ions in initial interactions among culture medium, osteoblasts and titanium surfaces. On the apatite coating surface, calcium ions are active sites for osteoblast adhesion, while calcium and phosphate ions co-exist on titanium surfaces, the former promotes the osteoblast adhesion onto the phosphate sites on titanium surfaces. The cell adhesion was a complicated biological and chemical process relating to surface several elements similar to protein adsorption.

Intravascular irradiation with beta emitters inhibits restenosis in arteries after balloon angioplasty or stent implantation. Yttrium-90 ((90)Y, T(1/2)=64 h) and cerium-144 ((144)Ce, T(1/2)=286 d) emit beta particles (E(max)=2.28--3.50 MeV) having an ideal energy range for brachytherapy delivery system. In this article, a previously reported method for depositing (32)P on poly(ethylene terephtalate) (PET) surfaces is generalized and modifications that allow deposition of other beta-emitting radioisotopes, such as (90)Y and (144)Ce, are demonstrated. PET films were first coated with chitosan hydrogel and then adsorbed different amounts of phosphoric acid (PA) in aqueous solutions. Yttrium was deposited onto the surface as YPO(4) after the films were immersed in YCl(3) solutions. 1 muCi (90)YCl(3) (2 x 10(-9) g) was used in each sample as a tracer for measuring the deposition efficiency, which is defined as the percentage of YCl(3) deposited on the surface compared to the amount of YCl(3) in solutions before the deposition. In order to improve the safety of brachytherapy treatments, polyurethanes were used to seal the deposited radioisotopes on the surface to minimize the leakage of the isotopes into the patients. The generality of this method presented here for a wide variety of particular radioisotopic components allows design of a broad range of versatile radioisotope sources.

Chitosan and chitosan hydrogel were immobilized on both the inside and outside surfaces of high density polyethylene (HDPE) tubes with 2.5x4 mm diameters. First, acrylic acid was grafted on the surfaces of HDPE by electron beam (2.5 Mrad) preirradiation method. Then chitosan/HCl and chitosan/lactic acid solutions were coated on the modified hydrophilic HDPE surfaces, the latter could form a pH-sensitive hydrogel layer on the surfaces. The tube surfaces were further modified with heparin by surface interpenetrating method to improve blood compatibility. ATR-FTIR and ESCA methods were used to characterize the coated surfaces. The morphology changes were monitored by Scanning Electron Microscope (SEM).

Recent data indicate that intravascular βa-irradiation from centrally located sources at the time of balloon angioplasty or stenting reduces proliferation of smooth muscle cells, neointima formation, and restenosis. In an effort to simplify radiation delivery, a novel β-radiation source was developed based on the adso rption of 32 P (phosphoric acid) by pH-sensitive chitosan hydrogel on a poly(ethylene terephthalate) balloon surface. To prevent the 2 P-isotope desorption in the patient's blood, the adsorbed phosphoric acid was precipitated as CaHPO 4 on the surface by a saturated Ca(OH) 2 /5% CaCl 2 solution. Various polyurethanes were applied to seal the radioactive surface by the dip-coating method. The isotope off-rate results were determined. Optimal results were obtained by serially coating with two polyurethane solutions. This approach holds promise for simplifying and improving the safety, and minimizing the cost of intravascular brachytherapy.

The thermal degradation properties of chitosan and lactic and/or glycolic acid grafted chitosan have been studied by differential scanning calorimetry (DSC) and thermogravimetric analyses (TG) in the range of 25–500°C. Both DSC and dynamic TG results show that the samples are thermal degraded easily after grafting the lactic and/or glycolic acid. From the isothermal TG experiments, the initial activation energy and the activation energy at different stages is obtained. The initial activation energy of all grafted samples is much lower than that of chitosan, especially for the sample GA/CS=2 and it varies with degree of conversion. The FT–IR spectra of thermally degraded residues give an indication of the chitosan polyscaccharide ring degradation after 30 min in 280°C, while sample GA/CS=2 will degrade only after 15 min.

Physically crosslinked chitosan hydrogels were synthesized by grafting D,L-lactic acid (LA) and/or glycolic acid (GA) with different feed ratios. The physical crosslinking was formed due to the hyd ...

Restenosis after percutaneous interventions in coronary and peripheral arteries leads to repeat procedures and surgery in a significant number of patients. We have previously demonstrated that irradiation of an arterial site using an endovascular source (brachytherapy) is highly effective in preventing the restenotic process. To this end, a novel beta radiation delivery system was developed, based on the adsorption of (32)P (o-phosphoric acid) by pH-sensitive chitosan hydrogel on a poly(ethylene terephthalate) (PET) balloon surface. The PET balloon surface was treated with oxygen plasma and coated with chitosan hydrogel. Covalent bonds, ionic bonds, and hydrogen bonds all contribute to the adhesion between chitosan hydrogel and PET. In the aqueous phosphoric acid (PA) solution, the -NH(2) groups of chitosan were protonated by PA and the adsorption of PA occurred at the same time. The effect of PA concentration and temperature on adsorption efficiency and kinetics were studied. More than 70% PA was adsorbed on the sample surface in 0.2 mM PA solution. The surface of samples was also investigated by attenuated total reflection-Fourier transform infrared spectroscopy and scanning electron microscopy. PET surface may be modified to carry high activity beta emitters; such materials may be useful in a therapeutic setting

Novel pH-sensitive physically crosslinked hydrogels were synthesized by grafting D,L-lactic acid (LA) onto the amino groups in chitosan (CS) without a catalyst. The structures of these graft copolymers were analyzed by FTIR and X-ray measurements. Degree of substitution, side-chain length, and yield of copolymers were evaluated from 1H-NMR, salicylaldehyde, and elemental analysis. The crystallinity of chitosan gradually decreased after grafting, since the side chains substitute the NH2 groups of chitosan randomly along the chain and destroy the regularity of packing between chitosan chains. Water uptake of the hydrogels was investigated as a function of side-chain length and degree of substitution. The influence of pH and salt concentration on the swelling behavior of the hydrogels was determined and interpreted. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3193–3202, 1999

Graft copolymerization of D,L-lactic acid (LA) onto chitosan (CS) was attempted without using a catalyst. pH-sensitive hydrogels were obtained which are based on two different components: a natural polymer and a synthetic polymer. These polyester substituents provide the basis for hydrophobic interactions that contribute to the formation of hydrogels. The swelling mechanisms in enzyme-free simulated gastric fluid (SGF, pH 2.2) or simulated intestinal fluid (SIF, pH 7.4) at 37°C were investigated. Meanwhile, structural changes of the graft copolymers in the different pH buffers were studied by FTIR, and these are discussed together with the swelling mechanisms. The effect of pH on the water uptake of hydrogel was investigated by using McIlvaine buffer with the same ionic strength. The morphological change of hydrogels in different aqueous solutions is investigated by scanning electron microscopy (SEM). © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3186–3192, 1999