bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lipase‐catalyzed synthesis of polymeric prodrugs of nonsteroidal anti‐inflammatory drugs
Authors: Qian Xueqi , Wu Qi , Xu Fangli , Lin Xianfu 
Published: September 2012

AbstractBecause of the potential application of prodrugs of nonsteroidal anti‐inflammatory drugs (NSAIDs), Candida antarctica lipase B (CAL‐B) catalyzed polycondensation of profen‐containing diol monomers and diesters were designed to prepare a series of biodegradable polymeric prodrugs composed of NSAID branches and poly(amide‐co‐ester) backbone. The structure of the products was confirmed by Fourier transform infrared spectroscopy, NMR, and gel permeation chromatography (GPC). The reaction conditions of polymerization, such as the enzyme source, amount of catalyst, and temperature, were optimized. The molecular weights of resultant copolymers were 2170–13,270 g/mol, with corresponding polydispersities from 1.17 to 2.4. The copolymers had relatively high drug loadings of 44.7–59.7 wt % because every repeat unit contained one drug molecule. The strategy of enzymatic polymerization appeared to be quite general and accommodated a large number of comonomer substrates with various chain lengths and substituents. The optically pure (R)‐naproxen monomer was demonstratively incorporated into the corresponding copolymers with the developed synthesis strategy. The in vitro study showed that the polyester could release the drug effectively under physiological conditions with enzyme, which indicated that the obtained product could be a promising prodrug for extending pharmacological effects by delayed drug release. With GPC analysis, we confirmed that the prodrug was completely degradable in aqueous solution. The attractive features of the copolymer were its high drug loading, biodegradability, and biocompatibility. The high tolerance of the CAL‐B toward drug groups, as described in this article, provides a new route for synthesizing polymeric drugs with potential biomedical applications in mild conditions and for reducing environmental impact. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Synthesis and properties of an insoluble chitosan resin modified by azamacrocycle copper(II) complex for protein hydrolysis
Authors: Wang Xingyu , Wang Dongfeng , Liang Peng , Liang Xingguo 
Published: September 2012

AbstractWe reported the synthesis process and the proteolytic ability of a novel crosslinked chitosan resin modified by azamacrocycle copper complex (CMCR). Characterization of CMCR showed that the Cu(II)Cyclen complex had successfully bound to the resin matrix covalently. Its proteolytic activity toward peptide bonds was evaluated by investigating the hydrolysis of bovine serum albumin in heterogeneous media. The maximum‐observed pseudo‐first‐order rate constant (kobs) was achieved under 60°C, pH 6.0, where protein was hydrolyzed into smaller peptides and amino acids confirmed by SDS–PAGE and ninhydrin reaction. The results indicated that the hydrolyzing efficiency delivered by CMCR was 4 × 105 times higher than that of spontaneous hydrolysis. CMCR also featured a desirable stability for chelating Cu2+ ions, which paved the way for its feasible recovery process and good reusability. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci, 2013
Development and characterization of new AR glass fiber‐reinforced cements with potential medical applications
Authors: Furtos Gabriel , Tomoaia‐Cotisel Maria , Baldea Bogdan , Prejmerean Cristina 
Published: September 2012

AbstractThe aim of this study was to obtain and investigate new biomedical glass fiber resin cements with improved mechanical properties and radiopacity, using alkaline‐resistant (AR) glass fibers. New light‐curing, self‐curing, and dual‐curing resin cements were obtained from AR glass fibers and BaSO4 powder mixed with 2,2‐bis[4‐(2‐hydroxy‐3‐methacryloyloxypropoxy)‐phenyl]propane and triethyleneglycol dimethacrylate monomers at different weight ratios, such as 5/20/75, 10/20/70, 20/20/60. The newly obtained cements were investigated for mechanical properties—compressive yield strength (CYS), compressive modulus (CM), diametral tensile strength (DTS)—as well as for radiopacity. Slight increases in CYS, CM, DTS and improved radiopacity with increasing amount of glass fibers were observed. The mechanical properties were found to increase in the order light‐curing < self‐curing < dual‐curing. SEM images support the reinforcement of resin cements by glass fibers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Effect of PEO on the network structure of PVA hydrogels prepared by freezing/thawing method
Authors: Lian Zhe , Ye Lin 
Published: September 2012

AbstractPoly(vinyl alcohol) (PVA)/poly(ethylene oxide) (PEO) hydrogels were prepared by freezing/thawing method for application as a wound dressing. The effect of PEO content on the network structure of PVA hydrogel was investigated in terms of crystalline and reological properties. It was found that a low amount of PVA crystallites were present in PVA/PEO hydrogels. With increasing content of PEO, the crstallinity of PVA hydrogel decreased, but the apparent dimensions of crystallites increased. The shear storage modulus (G′) decreased slightly with the increasing temperature within 30–50°C, probably resulting from the breaking of the hydrogen bonding; while it decreased sharply within 50–70°C, probably resulting from the melt of the crystallites of PVA hydrogel. The physical crosslinking density (Dpc) increased with decreasing PEO content, while decreased more dramatically with increasing temperature, indicating that hydrogen bonding was easier to be broken at high temperature. At very low strain amplitudes, the loss modulus (G″) of the hydrogel is lower than the storage modulus (G′) and G′ is independent of the strain amplitude, indicating that the deformation imposed on the network structure is entirely reversible. With increasing content of PEO, G′ at low frequency decreased, and the mesh size (Lc) increased, indicating of the decrease of the physical crosslinking density of PVA/PEO hydrogels. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Swelling behavior of physical and chemical DNA hydrogels
Authors: Karacan Pinar , Cakmak Husniye , Okay Oguz 
Published: September 2012

AbstractDNA hydrogels were prepared from aqueous solutions of double‐stranded DNA (about 2000 base pairs long) by physical and chemical means. Physical gels were obtained via denaturation–renaturation cycle of 5% aqueous DNA solutions between 25 and 90°C. Although physical DNA gels exhibit a high modulus of elasticity, the crosslinks holding the DNA network together are destroyed during the expansion of gels in water or in dilute salt solutions. It was shown that these gels can be used for the controlled release of DNA in aqueous media. Chemical DNA gels formed using ethylene glycol diglycidyl ether crosslinker are stable in water with a wide range of swelling ratios that could be adjusted by the amount of DNA at the gel preparation. Swelling behavior of chemical DNA gels in acetone/water mixtures as well as in aqueous salt solutions is very similar to that of synthetic polyelectrolyte hydrogels. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Hydrolysis of birch wood by simultaneous ball milling, dilute citric acid, and fungus Penicillium simplicissimum treatment at room temperature
Authors: Yuan Li , Chen Zhenhua , Zhu Yonghua , Liu Xuanming , Liao Hongdong , Chen Ding 
Published: September 2012

AbstractIn this study, birch wood chips were treated in one‐step ball milling (BM) hydrolysis with dilute citric acid and fungus Penicillium simplicissimum at room temperature and atmospheric pressure. An efficient conversion process for the production of fermentable sugars from woody biomasses using wet BM system was developed, in which wood lignocellulose was hydrolyzed into reducing sugars with the total yield of 245.3 mg/g wood. The concentrations of several major substances in the hydrolyzate were discussed in detail. The yields of the monomeric sugars were notably increased in the presence of fungus P. simplicissimum. Corresponding structure transformations before and after milling were analyzed by X‐ray diffraction, UV spectroscopy, transmission Fourier transform infrared spectroscopy, and environmental scanning electron microscopy clearly indicated that this combined treatment could be attributed to the crystalline and chemical structure changes of wood lignocellulose during BM. When compared with traditional method of BM, this work showed a more simple, novel, and environmental friendly way in mechanochemical treatment of lignocellulosic biomass, especially woody biomass. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Morphological diversity and nanofiber networks of poly(p‐oxybenzoyl) generated by phase separation during copolymerization
Authors: Ichimori Toshimitsu , Mizuma Kenta , Uchida Tetsuya , Yamazaki Shinichi , Kimura Kunio 
Published: September 2012

AbstractPoly(p‐oxybenzoyl) (POB) precipitates prepared by reaction‐induced phase separation during copolymerization exhibit wide variety of morphologies such as fibril, needle, slab, spindle, and sphere. The morphology is significantly influenced by the copolymerization conditions of structure of trifunctional comonomers, copolymerization ratio, solvent, concentration, and temperature of the polymerization. Among them, POB nanofiber networks like a texture of nonwoven fabrics are obtained only by the polymerization of 4‐acetoxybenzoic acid with 3,5‐diacetoxybenzoic acid (DABA) in aromatic solvent at a concentration of 1.0–2.0% at the content of DABA in feed of 10–20 mol % at 320°C. The network is comprised of fibrillar crystals connected each other at spherical nodal points. The diameters of the fibers are 90–129 nm. This network is highly crystalline and the molecules are aligned along the long direction of the fibers. Various parameters characterized the networks can be controlled by the polymerization concentration. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Systematic review and meta-analysis of the evidence for flexible sigmoidoscopy as a screening method for the prevention of colorectal cancer
Authors: Littlejohn C , Hilton S , Macfarlane G J , Phull P 
Published: September 2012

Abstract

Background
Colorectal cancer is a significant cause of death. Removal of precancerous adenomas, and early detection and treatment of cancer, has been shown to reduce the risk of death. The aim of this review and meta-analysis was to determine whether flexible sigmoidoscopy (FS) is an effective population screening method for reducing mortality from colorectal cancer.

Methods
MEDLINE (1946 to December 2012) and Embase (1980–2012, week 15) were searched for randomized clinical trials in which FS was used to screen non-symptomatic adults from a general population, and FS was compared with either no screening or any other alternative screening methods. Meta-analysis was carried out using a random-effects Mantel–Haenzsel model.

Results
Twenty-four papers met the inclusion criteria, reporting results from 14 trials. Uptake of FS was usually lower than that for stool-based tests, although FS was more effective at detecting advanced adenoma and carcinoma. FS reduced the incidence of colorectal cancer after screening, and long-term mortality from colorectal cancer, compared with no screening in a selected population. Compared with stool-based tests in a general population, FS was associated with fewer interval cancers.

Conclusion
FS is efficacious at reducing colorectal cancer mortality compared with no screening. It is more effective at detecting advanced adenoma and carcinoma than stool-based tests. FS may be compromised by poorer uptake. Introduction of FS as a screening method should be done on a pilot basis in populations in which it is not currently used, and close attention should be paid to maximizing uptake. The relative risk of adverse events with FS compared with stool-based tests should be quantified, and its real-world effectiveness evaluated against the most effective stool-based tests.
Systematic review and meta-analysis of safety of laparoscopicversusopen appendicectomy for suspected appendicitis in pregnancy
Authors: Wilasrusmee C , Sukrat B , McEvoy M , Attia J , Thakkinstian A 
Published: September 2012

AbstractBackgroundLaparoscopic appendicectomy has gained wide acceptance as an alternative to open appendicectomy during pregnancy. However, data regarding the safety and optimal surgical approach to appendicitis in pregnancy are still controversial.MethodsThis was a systematic review and meta-analysis of studies comparing laparoscopic and open appendicectomy in pregnancy identified using PubMed and Scopus search engines from January 1990 to July 2011. Two reviewers independently extracted data on fetal loss, preterm delivery, wound infection, duration of operation, hospital stay, Apgar score and birth weight between laparoscopic and open appendicectomy groups.ResultsEleven studies with a total of 3415 women (599 in laparoscopic and 2816 in open group) were included in the analysis. Fetal loss was statistically significantly worse in those who underwent laparoscopy compared with open appendicectomy; the pooled relative risk (RR) was 1·91 (95 per cent confidence interval (c.i.) 1·31 to 2·77) without heterogeneity. The pooled RR for preterm labour was 1·44 (0·68 to 3·06), but this risk was not statistically significant. The mean difference in length of hospital stay was − 0·49 (−1·76 to − 0·78) days, but this was not clinically significant. No significant difference was found for wound infection, birth weight, duration of operation or Apgar score.ConclusionThe available low-grade evidence suggests that laparoscopic appendicectomy in pregnant women might be associated with a greater risk of fetal loss.
Preoperative cardiopulmonary exercise testing and risk of early mortality following abdominal aortic aneurysm repair8
Authors: Hartley R A , Pichel A C , Grant S W , Hickey G L , Lancaster P S , Wisely N A , McCollum C N , Atkinson D 
Published: September 2012

Abstract

Background
Cardiopulmonary exercise testing (CPET) provides an objective assessment of functional capacity. The aim of this study was to assess whether preoperative CPET identifies patients at risk of early death following elective open and endovascular abdominal aortic aneurysm (AAA) repair.

Methods
Prospective data were collected from a pilot study between September 2005 and February 2007, and from all patients who underwent CPET before elective AAA repair at two vascular centres between February 2007 and November 2011. Symptom-limited, maximal CPET was performed on each patient. Univariable and multivariable analyses were used to identify risk factors for 30- and 90-day mortality.

Results
Some 415 patients underwent CPET before elective AAA repair. Anaerobic threshold (AT), peak oxygen consumption (peak V̇o2) and ventilatory equivalents for carbon dioxide were associated with 30- and 90-day mortality on univariable analysis. On multivariable analysis, open repair (odds ratio (OR) 4·92, 95 per cent confidence interval 1·55 to 17·00; P = 0·008), AT below 10·2 ml per kg per min (OR 6·35, 1·84 to 29·80; P = 0·007), anaemia (OR 3·27, 1·04 to 10·50; P = 0·041) and inducible cardiac ischaemia (OR 6·16, 1·48 to 23·07; P = 0·008) were associated with 30-day mortality. Anaemia, inducible cardiac ischaemia and peak V̇o2 less than 15 ml per kg per min (OR 8·59, 2·33 to 55·75; P = 0·005) were associated with 90-day mortality on multivariable analysis. Patients with two or more subthreshold CPET values were at increased risk of both 30- and 90-day mortality.

Conclusion
An AT below 10·2 ml per kg per min, peak V̇o2 less than 15 ml per kg per min and at least two subthreshold CPET values identify patients at increased risk of early death following AAA repair.
A fast automatic frequency calibration technique for a 2–6 GHz frequency synthesizer
Authors: Jeong Chan‐Young , Choi Dong‐Ho , Yoo Changsik 
Published: September 2012

AbstractA fast automatic frequency calibration (AFC) technique is described. For fast AFC operation while eliminating the uncertainty of the initial phase relationship between the reference clock and voltage‐controlled oscillator output, two‐phase reference clocks are employed. The proposed AFC scheme is applied to a 2–6 GHz frequency synthesizer. The frequency synthesizer is implemented in a 0.18 µm complementary metal–oxide–semiconductor process and occupies 0.92 mm2 while the AFC occupies only 0.01 mm2. The AFC operation is completed in less than 1.6 µs. Copyright © 2012 John Wiley & Sons, Ltd.
What does population structure analysis reveal about the Pterostylis longifolia complex (Orchidaceae)?
Authors: Janes Jasmine K. , Steane Dorothy A. , Vaillancourt René E. 
Published: September 2012

AbstractMorphologically similar groups of species are common and pose significant challenges for taxonomists. Differences in approaches to classifying unique species can result in some species being overlooked, whereas others are wrongly conserved. The genetic diversity and population structure of the Pterostylis longifolia complex (Orchidaceae) in Tasmania was investigated to determine if four species, and potential hybrids, could be distinguished through genomic AFLP and chloroplast restriction‐fragment‐length polymorphism (RFLP) markers. Analysis of molecular variance (AMOVA) results indicated that little genetic variation was present among taxa, whereas PCoA analyses revealed genetic variation at a regional scale irrespective of taxa. Population genetic structure analyses identified three clusters that correspond to regional genetic and single taxon‐specific phenotypic variation. The results from this study suggest that “longifolia” species have persisted throughout the last glacial maximum in Tasmania and that the complex may be best treated as a single taxon with several morphotypes. These results could have serious evolutionary and conservation implications as taxonomic changes could result in the instatement of a single, widespread taxon in which rarer morphotypes are not protected.
Effects of the peroxisome proliferator di(2-ethylhexyl)phthalate on cell turnover and peroxisome proliferation in primary chick embryo hepatocytes
Authors: Arias Elio 
Published: September 2012

Abstract
The peroxisome proliferator (PP) di(2-ethylhexyl)phthalate (DEHP) is widely used as a plasticizer and can contaminate air, water, and soil. As yet, no data have been published on its potential to induce changes in cell growth of nonmammalian hepatocytes. In the present study, the effects of DEHP on cell turnover and induction of peroxisome proliferation were evaluated in primary hepatocyte cultures from chick embryos. Cells were treated after attachment with 0, 25, 50, 75, and 100 µM DEHP for up to 96 h. S-phase increased significantly (p &lt; 0.01) from a background level of 5.5 ± 0.1% in solvent-control hepatocytes to a maximum level of 7.1 ± 0.1% in cells exposed for 48 h to 100 µM DEHP and decreased to near 6% by 96 h. Lower (p &lt; 0.05) levels of induction were seen at 50 and 75 µM DEHP. Spontaneous apoptosis showed a slight (p &lt; 0.05) decrease in hepatocytes treated with ≥75 µM dosages, as measured at 72 to 96 h. Induction of peroxisome proliferation was observed for cultures treated with ≥75 µM dosages at 48 h onwards. The results of the present study indicate that avian species may be responsive to the effects of PPs and may thus be affected by the presence of DEHP in the environment, but that this species is less sensitive than rodents. Environ. Toxicol. Chem. 2012; 31: 2856–2860. © 2012 SETAC
Bridging environmental mixtures and toxic effects
Authors: Allan Sarah E. , Smith Brian W. , Tanguay Robert L. , Anderson Kim A. 
Published: September 2012

Abstract
Biological Response Indicator Devices Gauging Environmental Stressors (BRIDGES) is a bioanalytical tool that combines passive sampling with the embryonic zebrafish developmental toxicity bioassay to provide a quantitative measure of the toxicity of bioavailable complex mixtures. Passive sampling devices (PSDs), which sequester and concentrate bioavailable organic contaminants from the environment, were deployed in the Willamette and Columbia Rivers within and outside of the Portland Harbor Superfund site in Portland, OR, USA. Six sampling events were conducted in the summer and fall of 2009 and 2010. Passive sampling device extracts were analyzed for polycyclic aromatic hydrocarbon (PAH) compounds and screened for 1,201 chemicals of concern using deconvolution-reporting software. The developmental toxicity of the extracts was analyzed using the embryonic zebrafish bioassay. The BRIDGES tool provided site-specific, temporally resolved information about environmental contaminant mixtures and their toxicity. Multivariate modeling approaches were applied to paired chemical and toxic effects data sets to help unravel chemistry–toxicity associations. Modeling elucidated spatial and temporal trends in PAH concentrations and the toxicity of the samples and identified a subset of PAH analytes that were the most highly correlated with observed toxicity. Although the present study highlights the complexity of discerning specific bioactive compounds in complex mixtures, it demonstrates methods for associating toxic effects with chemical characteristics of environmental samples. Environ. Toxicol. Chem. 2012; 31: 2877–2887. © 2012 SETAC
Intraframe quantization of speech line spectrum pairs for code‐excited linear prediction based coders in packet networks
Authors: Merazka Fatiha 
Published: September 2012

ABSTRACTThis paper proposes intraframe quantization schemes of line spectrum pair parameters to improve frame erasures for the ITU‐T G.723.1 coder. The standard ITU‐T G.723.1 coder uses an interframe quantization of the line spectrum pair parameters, which causes error propagation to the next frames. Simulation results show that our intraframe quantization schemes coding is much more robust to frame erasures than the embedded method in ITU‐T G.723.1, and a typical improvement of 0.4 dB on average spectral distortion can be obtained with 40% packet loss. Enhanced modified bark spectral distortion tests, under various packet loss conditions, confirm that our proposed method is superior to the interframe algorithm embedded in the ITU‐T G.723.1 coder of over 1.6. Copyright © 2012 John Wiley & Sons, Ltd.