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PI3Kδ is expressed predominately in leukocytes and overexpressed in B-cell-related malignances. PI3Kδ has been validated as a promising target for cancer therapy, and specific PI3Kδ inhibitors were approved for clinical practice. However, the substantial toxicity and relatively low efficacy as a monotherapy in diffuse large B-cell lymphoma (DLBCL) limit their clinical use. In this study, we described a novel PI3Kδ inhibitor SAF-248, which exhibited high selectivity for PI3Kδ (IC50= 30.6 nM) over other PI3K isoforms at both molecular and cellular levels, while sparing most of the other human protein kinases in the kinome profiling. SAF-248 exhibited superior antiproliferative activity against 27 human lymphoma and leukemia cell lines compared with the approved PI3Kδ inhibitor idelalisib. In particular, SAF-248 potently inhibited the proliferation of a panel of seven DLBCL cell lines (with GI50values < 1 μM in 5 DLBCL cell lines). We demonstrated that SAF-248 concentration-dependently blocked PI3K signaling followed by inducing G1phase arrest and apoptosis in DLBCL KARPAS-422, Pfeiffer and TMD8 cells. Its activity against the DLBCL cells was negatively correlated to the protein level of PI3Kα. Oral administration of SAF-248 dose-dependently inhibited the growth of xenografts derived from Pfeiffer and TMD8 cells. Activation of mTORC1, MYC and JAK/STAT signaling was observed upon prolonged treatment and co-targeting these pathways would potentiate the activity of SAF-248. Taken together, SAF-248 is a promising selective PI3Kδ inhibitor for the treatment of DLBCL and rational drug combination would further improve its efficacy.

Fibroblast growth factor receptor (FGFR) is a promising anticancer target. Currently, most FGFR inhibitors lack sufficient selectivity and have nonnegligible activity against kinase insert domain receptor (KDR), limiting their feasibility due to the serious side effects. Notably, compensatory activation occurs among FGFR1–4, suggesting the urgent need to develop selective pan-FGFR1–4 inhibitors. Here, we explored the antitumor activity of DW14383, a novel irreversible FGFR1–4 inhibitor. DW14383 exhibited equivalently high potent inhibition against FGFR1, 2, 3 and 4, with IC50values of less than 0.3, 1.1, less than 0.3, and 0.5 nmol/L, respectively. It is a selective FGFR inhibitor, exhibiting more than 1100-fold selectivity for FGFR1 over recombinant KDR, making it one of the most selective FGFR inhibitors over KDR described to date. Furthermore, DW14383 significantly inhibited cellular FGFR1–4 signaling, inducing G1/S cell cycle arrest, which in turn antagonized FGFR-dependent tumor cell proliferation. In contrast, DW14383 had no obvious antiproliferative effect against cancer cell lines without FGFR aberration, further confirming its selectivity against FGFR. In representative FGFR-dependent xenograft models, DW14383 oral administration substantially suppressed tumor growth by simultaneously inhibiting tumor proliferation and angiogenesis via inhibiting FGFR signaling. In summary, DW14383 is a promising selective irreversible pan-FGFR inhibitor with pan-tumor spectrum potential in FGFR1–4 aberrant cancers, which has the potential to overcome compensatory activation among FGFR1–4.

One-pot synthesis of novel hydrogel-based anion exchange membranes (AEMs), with only a single-phase monomer mixture, was used to eliminate surface heterogeneity and generate reproducible electroconvective microvortices in the over-limiting region of the current–voltage characteristic (CVC) curves. Diallyldimethylammonium chloride (DDA) was used as the main component to provide the cation charge groups, and 2-hydroxyethyl methacrylate (HEMA) and ethylene glycol dimethyl acrylate (EGDMA) were used as the auxiliary structure monomers. The uniform membrane structure allowed reproducible and sensitive DNA detection and quantification, as probe–target surface complexes can gate the ion flux and produce large voltage shifts in the over-limiting region. Suppressed membrane curvature due to controlled swelling is a crucial part to avoid the reduction of depletion region for maintaining the influence of target gene hybridization. Fourier-transform infrared (FTIR) spectroscopy verified the synthesized membrane structure, with a residual vinyl group that allows easy carboxylation via additional photografting reaction. Consequently, a significantly higher DNA probe functionalization efficiency is obtained on the homogeneous AEMs, evidenced by the increasing nitrogen element content and bonding via X-ray photoelectron spectroscopy (XPS). The DDA content was optimized to provide a sufficient coulomb force between AEM and nucleic acid backbone to promote the specific binding efficiency but without high dimensional swelling which might change the surface geometry and restrict the voltage shifting for sensing in the over-limiting region, and the optimal DDA/HEMA ratio was found to be 4/10. The synthesized AEM sensor for recombinant 35S promoter sequence identification exhibited a reproducible calibration standard curve with dynamic range between 30 fM and 1 μM and high selectivity with only 0.01 V shift for 1 μM nontarget oligo.

Deregulated Polycomb repressive complex 2 (PRC2) is intimately involved in tumorigenesis and progression, making it an invaluable target for epigenetic cancer therapy. Disrupting the EZH2–EED interaction, which is required for PRC2 enzymatic activity, is a promising strategy for cancer treatment. However, this kind of inhibitors are still limited. The in-cell protein–protein interaction screening was conducted for approximately 1300 compounds by NanoBRET technology. Co-immunoprecipitation (Co-IP), protein thermal shift assay (PTSA), and cellular thermal shift assay (CETSA) were performed to investigate the regulation of PRC2 by AZD9291. The anti-tumor effects of AZD9291 on breast cancer (BC) cells and diffuse large B-cell lymphoma (DLBCL) cells were detected. MicroRNA array assay, luciferase reporter assay, and qRT-PCR were conducted to identify the interaction and regulation among AZD9291, EZH2, and miR-34a. We discovered that, AZD9291, a potent and selective EGFR inhibitor, disrupted the interaction of EZH2–EED, leading to impairment of PRC2 activity and downregulation of EZH2 protein. In addition, AZD9291 declined EZH2 mRNA expression via upregulating the expression of a tumor suppressor, miR-34a. Our results suggest that AZD9291 can serve as a lead compound for further development of antagonist of PRC2 protein–protein interactions and EZH2 mRNA may be a direct target of miR-34a through non-canonical base pairing.

Over half of patients with BRCA1-deficient cancers do not respond to treatment with poly(ADP-ribose) polymerase (PARP) inhibitors. In this study, we report that a combination of 53BP1 and BRCA1 may serve as a biomarker of PARP inhibitor sensitivity. Based on the mRNA levels of four homologous recombination repair (HR) genes and PARP inhibitor sensitivity, we selected BRCA1-deficient MDA-MB-436 cells to conduct RNA interference. Reducing expression of 53BP1, but not the other three HR genes, was found to lower simmiparib sensitivity. Additionally, we generated 53BP1−/−/BRCA1−/−clonal variants by the transcription activator-like effector nuclease (TALEN) technique and found that depleting 53BP1 impaired PARP inhibitor sensitivity with a 36.7-fold increase in their IC50values. Consistent with its effect on PARP inhibitor sensitivity, 53BP1 loss alleviated cell cycle arrest and apoptosis and partially restored HR function. Importantly, 53BP1 depletion dramatically reduced the ability of PARP inhibitors to suppress tumor growth in vivo. The inhibition rate of simmiparib was 74.16% for BRCA1-deficient MDA-MB-436 xenografts, but only 7.79% for 53BP1/BRCA1-deficient xenografts. Re-expressing 53BP1 in the dual-deficient cells restored PARP inhibitor sensitivity and the levels of HR regulators. Considering that at least 10% of BRCA1-deficient breast and ovarian cancers have reduced expression of 53BP1, using a combination of 53BP1 with BRCA1 as a biomarker for patient selection should reduce the number of patients undergoing futile treatment with PARP inhibitors.

Aim:Targeting the VEGF/VEGF receptor (VEGFR) pathway has proved to be an effective antiangiogenic approach for cancer treatment. Here, we identified 6-((2-((3-acetamidophenyl)amino)pyrimidin-4-yl)oxy)-N-phenyl-1-naphthamide (designated herein as DW10075) as a novel and highly selective inhibitor of VEGFRs.Methods:In vitro tyrosine kinase activity was measured using ELISA, and intracellular signaling pathway proteins were detected by Western blot analysis. Endothelial cell proliferation was examined with CCK-8 assays, and tumor cell proliferation was determined with SRB assays. Cell migration, tube formation and rat aortic ring assays were used to detect antiangiogenic activity. Antitumor efficacy was further evaluated in U87-MG human glioblastoma xenograft tumors in nude mice receiving DW10075 (500 mg·kg−1·d−1, po) for two weeks.Results:Among a panel of 21 kinases tested, DW10075 selectively inhibited VEGFR-1, VEGFR-2 and VEGFR-3 (the IC50values were 6.4, 0.69 and 5.5 nmol/L, respectively), but did not affect 18 other kinases including FGFR and PDGFR at 10 μmol/L. DW10075 significantly blocked VEGF-induced activation of VEGFR and its downstream signaling transduction in primary human umbilical vein endothelial cells (HUVECs), thus inhibited VEGF-induced HUVEC proliferation. DW10075 (1–100 nmol/L) dose-dependently inhibited VEGF-induced HUVEC migration and tube formation and suppressed angiogenesis in both the rat aortic ring model and the chicken chorioallantoic membrane model. Furthermore, DW10075 exhibited anti-proliferative activity against 22 different human cancer cell lines with IC50values ranging from 2.2 μmol/L (for U87-MG human glioblastoma cells) to 22.2 μmol/L (for A375 melanoma cells). In U87-MG xenograft tumors in nude mice, oral administration of DW10075 significantly suppressed tumor growth, and reduced the expression of CD31 and Ki67 in the tumor tissues.Conclusion:DW10075 is a potent and highly selective inhibitor of VEGFR that deserves further development.

In order to automatically identify the mobile phones' reviews that the users comment on the mobile phone on the internet and obtain valuable information from the reviews, this paper presents the process of constructing ontology for the mobile phones' reviews and preliminarily establish a domain ontology of the mobile phones' reviews. The ontology construction adopts the Protégé tool and the Seven Steps method of Stanford University research. The ontology can provide convenience for the semantic information mining on Web mobile phones' reviews, and it can provide a new method to effectively mine the use feelings of the phone from a large number of mobile phone users' reviews.

We propose a noise-robust continuous speech recognition (CSR) method for modeling and recognition. In recognition, we divide the continuous speech vectors to segments using proposed algorithm, then use DRA based on the segments for recognition. The proposed method efficiency is studied for noisy environment. DRA decreases the difference between the model and recognition continuous speech vectors. The new algorithm focuses on adjust the vectors by using different maxima in different segments. Segment-based DRA algorithm can make noisy speech feature vectors closer to the model. The average recognition rate has been improved at different noise and SNR conditions.

The bitmap of contact angle image collected from optics contact angle system was processed on Vectorization with step-scan method. Then, the outline curve of image was got with sample`s curve-fitting. The precision of contact angle which was calculated from that curve compared with out of vectorization increased greatly. Moreover, it could edit to the image expediently.

Stainless steels are widely used as orthopaedic and dental implant; however, bioadhesion in the case of thrombosis, inflammation, and infection is one of their major limitations. One way to tackle this problem is to graft the stainless steel surface with a zwitterionic polymer known for being anti-bioadhesive. Controlled atom transfer radical polymerization (ATRP) of zwitterionic poly(sulfobetaine methacrylate) (polySBMA) grafted from biomedical grade stainless steel surface was employed in this study. The interactions of polySBMA-grafted surfaces with biomacromolecules were demonstrated in vitro by the adhesion tests of plasma protein, blood cells, human MG63 osteoblast- and HT1080 fibroblast-like cells in biological complex media to evaluate their bioadhesive properties. Anti-microbial effects were also assessed for two most ordinary seen clinical bacteria, i.e., Escherichia coliand Staphylococcus epidermidis. Results showed that polySBMA-grafted surface exhibited evident bioadhesion resistance and conferring antibacterial efficacy. This work is also dedicated to deduce the effectiveness of polySBMA brushes’ conformational structure on the prevention of bioadhesion. To this aim, the anti-bioadhesive effect of polySBMA brushes prepared by dopamine- and silane-surfaced immobilization method was evaluated. Results show that polySBMA grafted from immobilized polydopamine interfacial layers achieved better bioadhesion resistance, which could be causally related to their greater grafting coverage, flexible brush conformational structures, and greater hydration capabilities.

Copolymer emulsions containing fluorine were prepared by emulsion polymerization with MMA, BA and G06B using SDBS as emulsifier. The copolymer was characterized by FTIR and DSC. The size and distribution of the latex particle in emulsion were obtained by particle size analyzer. The stability of emulsion was observed and the solvent resistance of latex films was investigated. Surface properties of the copolymer film were investigated by contact angle measurement. The results showed that adding fluorine group to copolymer could increase hydrophobic property of the latex film and decrease the surface free energy of copolymer film. Glass fiber will have excellent properties when combining with the copolymer emulsion.

Europium-doped nanocrystalline ZrO2: Eu3+ powders with different doped concentrations were prepared by emulsion processing method, with different doped concentration and calcination temperature on the material grain size, structure, size and luminescent properties. The results show that: Eu3+ has a stabilizing effect on tetragonal phase of ZrO2. Emission spectra indicates that the main emission peak in the 593m and 608m, “Blue Shift “will occur in 5D0 → 7F2 transition of the emission spectra of sample with the sintering temperature at 1000℃. Samples with the sintering temperature soaring, spectral emission intensity also increases.

Based on the vehicle load model for fatigue design, the stress influence line of the reinforcement in the concrete slab of northern approach of Jiubao bridge, a multi-span continous composite bridge, under the global live load was obtained by spatial frame structure finite element model, while the stress history of the reinforcement under the local live load was obtained by the spatial refined finite element model. Then the stress spectrums under global and local live load were obtained by Rain-flow method according to the predicted traffic volume in the future 100 years and comparisons of amplitudes of equivalent stress under different loads were achieved. At last the fatigue lives of the slab under the different loads were calculated and compared either.

A compatilizer PP-g-Vi-PDMS for PP/RTV blends was prepared through a melt extrusion-grafting method. The tentative mechanism of the enhanced compatibility effect was discussed. The interfacial tension of PP/RTV blends was calculated based on contact angle method. The results indicated the grafting reaction between PP and Vi-PDMS, which was demonstrated by both the decreasing melt flow rates with increasing Vi-PDMS contents and the appearing of IR peaks at 1260cm-1、1100~1000cm-1、800cm-1 ascribed to Vi-PDMS′s characteristic IR absorption. The compatilizer significantly decreased the interfacial tension of PP/RTV blends. The compatibility of PP/RTV blends was improved successfully using the compatilizer PP-g-Vi-PDMS.

Ramie fibers were incorporated into polypropylene as the reinforcement fillers. The transesterification between the hydroxyl groups of ramie fiber and the ester of maleic anhydride was employed to improve the compatibility of ramie fibers and the polypropylene matrix. The morphology of the composite surfaces and interfaces were studied using IR and SEM. The mechanical properties and water absorption of the composites were investigated. The results demonstrated that the esterification occurred on the surface of ramie fiber, due to which the compatibility between fiber and matrix treated was greatly improved. Because of the improved compatibility, the mechanical strength of the composites increased; while water absorption decreased.

Positron and Positronium chemistry has been pursued and advanced by many scientists and engineers in both fundamental understanding of Positronium atom and its applications to chemical and polymeric systems during the last decade. This paper presents our recent results from collaborative investigations of positron annihilation in polymeric membranes. Future perspectives of applying Positronium chemistry to membrane science and technology and other related disciplines of nanotechnology, chemical engineering, materials science, energy research, molecules with positrons, biological and medical sciences appear to be promising.

Polyhydroxyalkanoates (PHAs) is a newer family of biomaterials for tissue engineering applications. The objective of this study is to investigate the behaviors of human Schwann cells-like (hSCs-like) on various PHA films. The surface characteristics of PHA films were varied by the content of 3-hydroxyvalerate (HV) or 3-hydroxyhexanoate (HHx) and by the film preparation methods such as compression-molding and solvent-casting. Hyaluronic acid (HA) and poly(L-lysine) (PLL) were further applied on to improve the growth of hSCs-like on PHA membranes. The hSCs-like isolated from human body (MATERIALS AND METHODS) would have strong metabolic activities and produce many extracellular matrix (ECM). When HV content increased, there was a reduction in the crystallinity and the hydrophoicity of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) membranes. Despite that these different surface characteristics did not show significant effect on the metabolic activities of hSCs-like, these would affect adhering HA. Hyaluronic acid (HA)-coated PHA membranes could improve the metabolic activities and decrease the death ratio of hSCs-like. However, the condition of PLL coating has no obvious influence on the activities of hSCs.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

A series of sulfonated poly(aryl ether ether ketone ketone)s statistical copolymers with high molecular weights were synthesized via an aromatic nucleophilic substitution polymerization. The sulfonation content (SC), defined as the number of sulfonic acid groups contained in an average repeat unit, could be controlled by the feed ratios of monomers. Flexible and strong membranes in sodium sulfonate form could be prepared by the solution casting method, and readily transformed to their proton forms by treating them in 2 N sulfuric acid. The polymers showed high Tgs, which increased with an increase in SC. Membranes prepared from the present sulfonated poly(ether ether ketone ketone) copolymers containing the hexafluoroisopropylidene moiety (SPEEKK‐6F) and copolymers containing the pendant 3,5‐ditrifluoromethylphenyl moiety (SPEEKK‐6FP) had lower water uptakes and lower swelling ratios in comparison with previously prepared copolymers containing 6F units. All of the polymers possessed proton conductivities higher than 1 × 10−2 S/cm at room temperature, and proton conductivity values of several polymers were comparable to that of Nafion at high relative humidity. Their thermal stability, oxidative stability, and mechanical properties were also evaluated. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2299–2310, 2006

Purpose. Ammonio methacrylate copolymer is a pharmaceutical excipient widely used as a coating material for encapsulation of pellet and tablet dosage forms. Because of the charged ammonio function groups within the polymer, ionic drugs may interact with the coating film while transporting through it. The kinetic swelling and drug permeation properties of the ammonio methacrylate copolymer membranes were studied to delineate the effect of ionic interaction between the ionic drugs and the membranes. Methods. The pH and ionic strength of the solutions and the charged properties of drugs were varied to study the effects on the transport properties through the membranes. Ambroxol was chosen as a model cationic drug and aspirin as a model anionic drug. Results. The degree of membrane swelling in the drug-free solution decreases as the ionic strength increases but it is irrelevant to the pH. With the presence of ionic drugs, the degree of membrane swelling is affected by the drug species as well as the pH of the solutions in addition to the effect of ionic strength. The degree of swelling for a membrane in a solution containing aspirin is higher at a lower pH and ambroxol is lower at a lower pH. Aspirin experiences a three-stage permeation and ambroxol a two-stage one. The ion-exchange reaction between the anionic carboxylic groups in aspirin and the cationic ammonio groups in the membranes results in a slow permeation stage during the transient state. The pseudo steady-state permeability for each drug follows the trend as the degree of membrane swelling in the drug media at various pH and ionic strengths. However, it is much higher for aspirin than ambroxol although the degree of membrane swelling is higher in an ambroxol solution than that in an aspirin solution. The permeability of ambroxol through the membrane is largely reduced because of the Donnan exclusion effect. Conclusions. The interaction between ionic drugs with the cationic groups in the membranes affects the ionic strength of the solutions and results in a pH-dependent degree of swelling. The ionic interaction also determines the drug permeation rates as well as the transient permeation behaviors.

Poly(methyl methacrylate-co-N-isopropylacrylamide-co-N-acryloxysuccin-imide) (poly(MMA/NIPAAni/NAS)) latex particles were prepared by emulsifier-free emulsion polymerization. The latex particles could reversibly flocculate and disperse when the solution temperature was kept above and below the characteristic lower critical solution temperature (LCST). The LCST of the latex dispersion could be adjusted lower or higher by increasing or decreasing, respectively, the ionic strength of the solution.α-Amylase was immobilized onto the latex particles by reacting with the succinimide groups on NAS. It was demonstrated that the ct-amylase immobilized latex particles could be separated by thermoflocculation. After 5 repeated thermocycles, 83 % of the latex particles could be recovered, and the apparent enzymatic activity could be retained as high as 78percnt;.

The permeability and solubility for water and ethanol in PTFEP membranes were determined experimentally, and the data were analyzed by the solution-diffusion model. The permeability for water and ethanol ranged from several hundreds to several thousands Barrers, and they increased exponentially with the vapor activity and increased with temperature. At the same temperature and vapor activity, the permeability ratio between water and ethanol ranged from 5.7 to 2.3, and it decreased as the vapor activity increased. The sorption isotherms for water and ethanol were fitted by the Henry’s law relationship. The solubility decreased as the temperature increased so that the heat of sorption for both water and ethanol was negative. The solubility for water was more than twice the solubility for ethanol. The solubility seems to be inversely proportional to the molecular size of the penetrants in such a system. The solubility ratio between water and ethanol is smaller than their molecular volume ratio possibly due to the slightly stronger nonpolar interaction and the higher degree of plasticization in the ethanol-polymer system. The diffusivity for water and ethanol ranged from 10−8to 10−7cm2/s, and the values for water were larger than those for ethanol at the same temperature and vapor activity. The diffusivity for water and ethanol also increased exponentially with the vapor activity. The diffusivities for water and ethanol increased with temperature and their activation energies of diffusion were very similar possibly due to the same energy characteristic of polymer main chain movement.The permeability and solubility for water and ethanol in PTFEP membranes were determined experimentally, and the data were analyzed by the solution-diffusion model. The permeability for water and ethanol ranged from several hundreds to several thousands Barrers, and they increased exponentially with the vapor activity and increased with temperature. At the same temperature and vapor activity, the permeability ratio between water and ethanol ranged from 5.7 to 2.3, and it decreased as the vapor activity increased. The sorption isotherms for water and ethanol were fitted by the Henry’s law relationship. The solubility decreased as the temperature increased so that the heat of sorption for both water and ethanol was negative. The solubility for water was more than twice the solubility for ethanol. The solubility seems to be inversely proportional to the molecular size of the penetrants in such a system. The solubility ratio between water and ethanol is smaller than their molecular volume ratio possibly due to the slightly stronger nonpolar interaction and the higher degree of plasticization in the ethanol-polymer system. The diffusivity for water and ethanol ranged from 10−8to 10−7cm2/s, and the values for water were larger than those for ethanol at the same temperature and vapor activity. The diffusivity for water and ethanol also increased exponentially with the vapor activity. The diffusivities for water and ethanol increased with temperature and their activation energies of diffusion were very similar possibly due to the same energy characteristic of polymer main chain movement.

Pervaporation and sorption for the liquid mixture of benzene and cyclohexane by using poly[bis(phenoxy)phosphazene] (PPOP) membranes were characterized. Diffusivities, solubilities, interaction parameters, plasticization coefficients, and heats of sorption for benzene and cyclohexane in the membrane were determined from the vapor sorption kinetics and isotherms, which were measured gravimetrically by a continuous microbalance. Pervaporation operations offered a maximum selectivity of 3 at 35°C and the 35–50% feed concentration level of benzene. Normalized fluxes increased but the pervaporation selectivity decreased slightly with temperature. The binary transport in the membrane was modeled by the solution–diffusion model with an exponential form diffusivity to the concentration of each permeant. Coupling coefficients imbedded in the model were numerically determined by a proposed computation method. The model can illustrate not only concentration and diffusivity profiles for the permeants within the membrane, but their transport mechanism, which is consistent with the hypothesis of “two layers” in the membrane. The analysis of activation energy for transport indicates that the permeation barrier for pervaporation is reduced much more than that of the single‐vapor permeation through an unswollen membrane.

An experimental study was carried out to investigate the effect of ethylene glycol dimethacrylate (EGDMA, as a crosslinking agent) content on the curing kinetics of the polymerization of 2-hydroxyethyl methacrylate (HEMA), using differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). EGDMA may cause a crosslinking-facilitated gel effect which reduces the termination rate of living free radicals and enhances the overall reaction rate, but it may also induce a diffusional resistance for the reactants so that some free monomers are trapped and pendant vinyl groups are prohibited from reaction by the crosslinked structure. At higher content of EGDMA, the later effect becomes predominant, and the reaction rate and the final conversion are limited. The exothermic peak of the curing reaction tends to carry a shoulder and then split into two peaks as the amount of EGDMA is increased, possibly due to a later reaction of the trapped monomers and pendant vinyls. The heat of reaction measured by DSC in the scanning mode is 61.2 kJ/mol C(DOUBLEBOND)C. The activation energy (E) of the curing reaction ranges from 56.5 to 78.3 kJ/mol C(DOUBLEBOND)C depending on the EGDMA content and the type of operation. The diffusion-limited reaction rate and the different thermal history experienced in the nonisothermal and isothermal curing can result in variations of the results in the activation energy measurement. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1873–1889, 1997

The swelling, permeation, and release characteristics for benzoic acid, caffeine, propranolol hydrochloride, and diclofenac sodium in crosslinked poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels were examined. Increasing polymer crosslinking density resulted in decreases in the degree of swelling, drug loading, the diffusivity of solute in the hydrogels, and in the rate of drug release. Diclofenac sodium led to an abnormally large degree of swelling as the maximum value is given as 6.5, while the highest for the other three was 1.07. That the logarithmic drug diffusivity was proportional to the reciprocal of hydration indicates that the free volume theory accounts for the transport of solute in the gels. Increasing the concentration resulted in increases in the diffusivities, solubilities, and permeabilities of the solutes in the hydrogels. The drug release kinetics from most wet hydrogel samples can be well-fitted by a Fickian diffusion model. Near zero-order release is observed only for dry samples with caffeine of low loading.

Ionic crosslinking of the ferric ions and the carboxylic groups in the poly(vinyl alcohol-g-acrylic acid) (poly(VA-g-AA)) membranes improves the size screening effect in the pervaporation of ethanol-water separation. In the grafting polymerization of acrylic acid monomer onto poly(vinyl alcohol) (PVA), ferric ions are remained in the polymer membranes as the Fenton's reagent(Fe2+-H2O2) is used to initiate the reaction. Completely reversed trends in terms of the degree of swelling, the pervaporation selectivity, and the flux of permeates are obtained depending on that the ferric ions are present or absent in the membranes. The degree of swelling decreases, the pervaporation selectivity increases, and the flux decreases as the grafting percentage increases for the membranes containing ferric ions. The degree of swelling and the flux of permeates increase but the pervaporation selectivity is reduced as the grafting percentage increases for the membranes which were washed with acid to remove ferric ions.

Temperature-responsive N-isopropylacrylamide (NIPAAm) polymer (PNIPAAm) with a free carboxyl functional end group and a copolymer (NIPNAS) of NIPAAm and N-acryloxysuccinimide (NAS) were synthesized and used for immobilization of α-amylase. The enzyme forms covalent bonds with the former polymer by single point attachment and with the latter polymer by multiple point attachment. Such a difference influences the enzyme activity and properties of the immobilized enzymes. The polymers are temperature-sensitive with lower critical solution temperatures (LCST) of 34·7 and 36·0°C for NIPNAS and PNIPAAm, respectively. The immobilized enzyme exhibited an LCST of 35·5°C for NIPNAS-amylase and 37·1°C for PNIPAAm-amylase. They precipitated and flocculated in aqueous solution above the LCST and redissolved when cooled below that temperature. The activity of the immobilized enzyme depended on the pH of the coupling buffer, with 8·0 being the optimum value. The specific activities of the immobilized enzymes were 87% and 108% compared with that of free enzyme with soluble starch as the substrate for NIPNAS-amylase and PNIPAAm-amylase, respectively. By characterizing the properties of the immobilized enzymes and comparing with those of free enzyme, no diffusion limitation of substrate was found for the immobilized enzymes and they are more thermal stable than the free enzyme. Within the two immobilized enzymes, NIPNAS-amylase showed better thermal stability and reusability. Repeated batch hydrolysis of soluble starch can be carried out efficiently with the immobilized enzymes by intermittent thermal precipitation and recycle of the enzyme. © 1997 SCI.

A composite membrane was made by casting hydrogel onto a nonwoven polyester support and used for enzyme immobilization. The hydrogel consists of N‐isopropylacrylamide, cross‐linker N,N′‐methylenebis(acrylamide), 2‐hydroxyethyl methacrylate, soluble starch, and N‐(acryloxy)succinimide (NAS). The composite membrane is temperature‐sensitive with a lower critical solution temperature (LCST) around 35 °C. It responds to temperature change by swelling below the LCST and shrinking above the LCST, corresponding to opening and closing of the membrane pores. α‐Amylase was immobilized to the membrane by covalent bonds through reacting with the high reactive ester groups in NAS. The membrane‐immobilized enzyme retained 32% of specific activity toward soluble starch when compared with that of free enzyme, and its properties were characterized and compared with those of the free enzyme. The immobilized enzyme was more thermally stable than the free enzyme. Kinetic constants, (Km) and the activation energy of the immobilized enzyme were both larger than those of the free enzyme. Starch hydrolysis with the immobilized enzyme was investigated in two‐compartment permeation cells with a composite membrane between the cells. Reaction was carried out by hydrolyzing soluble starch in the donor side and collecting the hydrolyzed products in the receptor side. This reactor could be operated with temperature cycling to enhance the reaction and facilitate separation of products from the substrate. The best operating condition is cycling the temperature between 50 and 20 °C every 5 min. The membrane reactor was operated up to eight times for successive starch hydrolysis.