bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and characterization of a porous poly(hydroxyethylmethacrylate‐co‐ethylene glycol dimethacrylate)‐based hydrogel device for the implantable delivery of insulin
Authors: Kumar Amit , Tyagi Priyanka , Singh Harpal , Kumar Yougesh , Lahiri Sitanshu S. 
Published: April 2012

AbstractPoly(hydroxyethylmethacrylate‐co‐ethylene glycol dimethacrylate) [poly(HEMA‐co‐EGDMA)]‐based hydrogel devices were synthesized by a free‐radical polymerization reaction with 2‐hydroxyethylmethacrylate as the monomer, different concentrations of ethylene glycol dimethacrylate (EGDMA) as the crosslinking agent, and ammonium persulfate/N,N,N′,N′‐tetra‐methyl ethylenediamine as the free‐radical initiator. The porosity of the poly(HEMA‐co‐EGDMA) hydrogels was controlled with water as the porogen. The Fourier transform infrared spectrum of poly(HEMA‐co‐EGDMA) showed absorption bands associated with CO stretching at 1714 cm−1, COC stretching vibrations at 1152 cm−1, and a broad band at 3500–3800 cm−1 corresponding to OH stretching. Atomic force microscopy studies showed that the hydrogel containing 67% water had pores in the range of 3500–9000 nm, whereas the hydrogel containing 7% water did not show measurable pores. The hydrogel synthesized with 1% EGDMA showed 50% thallium‐201 release within the first 30 min and about 80% release within 60 min. In vitro insulin‐release studies suggested that the hydrogel with 27% water showed sustained release up to 120 min, whereas the hydrogels with 47 and 67% water showed that nearly all of the insulin was released within 60 min. Hydrogel devices synthesized with 27% water and filled with insulin particles showed sustained release for up to 8 days, whereas the hydrogels synthesized with 47 and 67% water released insulin completely within 3 days of administration. Animal studies suggested that the hydrogel devices synthesized with 27% water and filled with insulin‐loaded particles (120 IU) were able to control blood glucose levels for up to 5 days after implantation. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Stereochemical assignments of the nuclear magnetic resonance spectra of isobornyl acrylate/methacrylonitrile copolymers
Authors: Khandelwal Deepika , Hooda Sunita , Brar A. S. , Shankar Ravi 
Published: April 2012

AbstractIsobornyl acrylate (B)/methacrylonitrile (N) copolymers with different compositions were synthesized by the free‐radical bulk polymerization with azobisisobutyronitrile as the initiator under a nitrogen atmosphere at 70°C. The copolymer compositions were calculated from quantitative 13C(1H)NMR spectra. The reactivity ratios of the comonomers in the B/N copolymers determined from the linear Kelen–Tudos method and nonlinear error‐in‐variable method were rB = 0.66 ± 0.11 and rN = 1.54 ± 0.22 and rB = 0.74 and rN = 1.65, respectively. The complete spectral assignments of the 1H‐NMR and 13C(1H)‐NMR spectra were carried out with the help of distortionless enhancement by polarization transfer, two‐dimensional (2D) heteronuclear single quantum coherence, and 2D total correlation spectroscopy. The nitrile carbon of the N unit and the methine and OCH carbons of the B unit were assigned to triad compositional sequences, whereas the β‐methylene carbons of the B and N units were assigned to the tetrad compositional and configurational sequences. The α‐methyl carbon of the N unit was also assigned to the triad level of configurational and compositional sequences. Similarly, the nitrile and quaternary carbon resonances with the methine, methylene, and methyl protons were studied in detail with 2D heteronuclear multiple‐bond correlation spectra. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Biocompatible polypropylene prepared by a combination of melt grafting and surface restructuring
Authors: Shi Qiang , Zhao Jie , Stagnaro Paola , Yang Huawei , Luan Shifang , Yin Jinghua 
Published: April 2012

AbstractTo construct biocompatible surfaces of polypropylene (PP), poly(ethylene glycol) methyl ether methacrylate (PEGMEMA) was melt‐grafted onto PP backbones; this was followed by the restructuring of the surface mircostructure of the grafted PP by water treatment. The grafted products were analyzed by Fourier transform infrared spectroscopy and 1H‐NMR; the surface microstructure of the graft copolymer was characterized by X‐ray photoelectron spectroscopy and atomic force microscopy, and the biocompatibility was evaluated by water contact angle, protein adsorption, and platelet adhesion measurements. This study showed that highly biocompatible surfaces of PP could be obtained by a combination of melt grafting and surface restructuring techniques, and the formation of hole‐with‐rim patterns and the enrichment of the PEGMEMA chains on the topmost surface were the key factors for the improved biocompatibility. This work advances functionalized PP generated by melt grafting as a promising candidate for applications in blood‐contact devices. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Synthesis, characterization, and application of amylopectin‐graft‐poly(AM‐co‐AMPS)
Authors: Adhikary P. , Krishnamoorthi S. 
Published: April 2012

AbstractA series of graft copolymers poly(acrylamide‐co‐2‐acrylamido‐2‐methylpropanesulfonic acid) [Ap‐g‐p(AM‐co‐AMPS)] have been synthesized by graft copolymerization of amylopectin (Ap) with acrylamide (AM) and 2‐acrylamido‐2‐methylpropanesulfonic acid (AMPS). The copolymerization has been carried out by solution polymerization technique and using ceric ammonium nitrate (CAN) as initiator. The characterization of graft copolymer has been carried out by elemental analysis fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), and scanning electron microscopy (SEM). The effects of reaction conditions on graft copolymerization and the use of the copolymer as flocculating agent in kaolin suspension have been investigated. Experiments have shown that graft copolymer with higher grafting level, higher intrinsic viscosity, and higher anionic degree can be obtained by changing the method of addition of monomers and by controlling the ratio of AMPS and AM. The flocculation performances have been investigated through jar test method, and it has been observed that the graft copolymer with molar ratio of 2 : 1 of AM and AMPS shows best performance in flocculating kaolin suspension. Metal ion sorption study with Cu2+ has shown that the graft copolymer absorbs Cu2+ efficiently. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Relationship between dielectric behaviors and conversion of MMA during polymerization process
Authors: Lisheng Zhong , Bo Hu , Jingxuan Wu , Junwei Zhao , Guang Ouyang , Qinxue Yu 
Published: April 2012

AbstractPoly(methyl methacrylate), which is prepared by polymerization of methyl methacrylate (MMA), is widely used in the fabrication of polymer optical fiber and devices. In this article, a dielectric measurement method was proposed to monitor the polymerization process. The measurement result is compared with that obtained by the traditional Abbe's refractometer method. By monitoring the dielectric behaviors of polymerization system, the correlation between dielectric properties of reacting bulk and conversion of MMA was established. The influence of reactive temperature, reactive time, conversion rate of prepolymerization, and oxygen environment was discussed. It was shown that the gel effect occurred at 2 h at the reactive temperature of 50°C when the conversion of prepolymer was about 24% with the absence of oxygen. The conversion rate obtained by Abbe's refractometer method was larger than that measured by dielectric method in the reaction metaphase. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Films of native and modified starch reinforced with fiber: Influence of some extrusion variables using response surface methodology
Authors: Galicia‐García T. , Martínez‐Bustos F. , Jiménez‐Arévalo O. A. , Arencón D. , Gámez‐Pérez J. , Martínez A. B. 
Published: April 2012

AbstractCorn starch (native and phosphorylated) and potato films containing glycerol as plasticizer, and bagasse sugar cane as fiber, were produced by extrusion‐calendering process, and characterized for the mechanical properties (tensile stress at rupture σr, elongation at break εb, and Young's modulusE), water disintegration index (WDI), water absorption capacity (WAC), and luminosity. The evaluated processing variables were: feed moisture, fiber content, and type of starch. The response surface methodology was applied to analyze, and the model of significance was justified by a variance analysis (F‐test). The inclusion of fiber provides a mechanical reinforcement to the starch matrix favoring the elongation at break (εb) in thickness films (280–350 μm). Samples formulated with potato starch within the values of feed moisture 18.25, 20.5, and 5 wt % of fiber content, showed an increment in values of tensile stress at rupture (3.80–4.4 MPa) and Young's modulus (78.47–68.04 MPa). Corn starch films with high fiber content (10%) and low feed moisture (18.25%) values showed a decrement in elongation at break (12.93%). WAC and WDI were low with minimum and intermediate levels of feed moisture and fiber content (0–5%). Luminosity values were an indicative that do not exist degradation in film materials due to condition extrusion process used. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
A probabilistic approach to calculate capacity of signalized intersections with a red light camera
Authors: Jha Manoj K. , Weldegiorgis Yohannes 
Published: April 2012

SUMMARYIn recent years, red light cameras (RLCs) have been installed at many signalized intersections. The main reason behind installing RLCs is to reduce intersection‐related accidents caused because of a driver's behavior to cross the intersection when the signal turns red. By nature, if the driver is aware of the presence of RLC his or her driving behavior is bound to change. This behavioral change, however, may be intentional or unintentional. This may influence the utilization of yellow intervals resulting in a possible increase in dilemma zone, which in turn, may reduce the service capacity of the intersection. To accurately capture this capacity reduction, we present a probabilistic approach to modify the saturation flow rate formula in the Highway Capacity Manual that is currently used to calculate the capacity of signalized intersections. We introduce a new factor in the saturation flow rate calculation called red light reduction factor, to account for the capacity reduction owing to RLCs. Using field data from Baltimore, Maryland, we establish a relationship for the red light reduction factor. We then show that capacity of RLC‐equipped intersections is generally lower than that without RLCs. Although the percentage reduction in capacity of a single intersection may not seem significant, the cumulative impact of such reduction in a heavily traveled road network may be quite significant, resulting in significant loss in travel time. In future works, the systemwide capacity reduction owing to the presence of RLCs can be studied in congested transportation networks. Copyright © 2012 John Wiley & Sons, Ltd.
Effect of soft tissue thickness over the posterior border of the vertebral body and disc space on cage placement during posterior lumbar interbody fusion: A cadaveric study
Authors: Yang Jae Hyuk , Kasat Niraj Sharad , Whang Jin Ho , Kim Min Keun , Min Kyueng‐Whan , Hong Jae Young , Modi Hitesh N. , Suh Seung Woo 
Published: April 2012

AbstractIn the present study, we investigated whether there is a difference between visual depth (VD) and radiological image depth (RD) of cages (i.e., structural interbody support devices) placed in disc spaces during posterior lumbar interbody fusion and whether soft tissues covering the posterior border of the vertebral body and associated disc space are the cause of any observed differences. Using digital calipers, cages were inserted at a depth of 5 mm from the soft tissues covering the posterior border of the vertebral body and disc space under direct vision; this depth was defined as VD. After insertion, RD was measured in triplicate. The reliability of RD measurements was evaluated using an intraclass coefficient test. To identify the cause of differences between VD and RD, the thicknesses of soft tissues were measured microscopically. A total of 40 lumbar intervertebral disc spaces with cages were evaluated. The mean RD of cages was 3.12 mm, while the mean difference between the VD and RD of cages (DVRD) was 1.91 mm. On histological examination, the mean thickness of the soft tissue was 2.02 mm. Comparative analysis between histological values and DVRD showed no statistical difference (P = 1.14, 1.55, 0.06). There was a significant difference between VD and RD during cage placement, and soft tissue structure appeared to be responsible for the DVRD of inserted cages. Therefore, cages should be inserted deeper to account for differences between visual and radiological image depths. Clin. Anat. 25:1066–1073, 2012. © 2012 Wiley Periodicals, Inc.
Experimental and Computational Investigations of the Deactivation of H‐ZSM‐5 Zeolite by Coking in the Conversion of Ethanol into Hydrocarbons
Authors: Däumer Daniel , Räuchle Konstantin , Reschetilowski Wladimir 
Published: April 2012

AbstractThe catalytic conversion of ethanol into hydrocarbons on a H‐ZSM‐5 zeolite with a molar Si/Al ratio of 12 was investigated under different reaction conditions (WHSV, carrier flow). During catalyst‐deactivation, the selectivity changed towards C2 products. These results indicated that the deactivation neither correlated with the total amount of deposits nor with the structural damage of the zeolite. Under the assumption that a pore‐blockage caused the change in selectivity, characterization of the catalyst sample (TPAD, IR spectroscopy), the formed deposits (TGA, DSC), and also the regeneration process were performed. The experimental results were discussed in terms of the nature of the deposits (i.e., aromatic compounds, substituted aromatic compounds, or olefins) and correlated with quantum chemical calculations at the ONIOM(B3LYP/6‐31G(d):PM6) level of theory with a purely siliceous model to consider the effect of pore‐blockage in an inert SiO2 MFI network.
Post‐Synthetic Modification of Zr‐Metal–Organic Frameworks through Cycloaddition Reactions
Authors: Roy Pascal , Schaate Andreas , Behrens Peter , Godt Adelheid 
Published: April 2012

AbstractCycloaddition reactions are highly attractive for post‐synthetic modification of metal–organic frameworks (MOFs). We report herein on cycloaddition reactions with PIZOF(R1,R2)s, which are porous interpenetrated Zr‐based MOFs with Zr6O4(OH)4(CO2)12 as the nodes and the dicarboxylates −O2C[PE‐P(R1,R2)‐EP]CO2− (P: phenylene, E: ethynylene; R1, R2: side chains at the central phenylene unit) as the linkers. 1,3‐Dipolar cycloaddition between the pendant ethyne moieties of PIZOF(OMe,OCH2CCH) and 4‐methylbenzyl azide resulted in 98 % conversion of the ethyne groups. Reactions of PIZOF(OMe,O(CH2)3furan) with maleimide, N‐methylmaleimide, and N‐phenylmaleimide converted 98, 99, and 89 % of the furan moieties into the Diels–Alder adducts. However, no reaction occurred with maleic anhydride. High‐resolution 1H NMR spectra were crucial in determining the conversion and identifying the reaction products. Of all the reagents (NaOD/D2O, D2SO4, Bu4NF, CsF, CsF/DCl, and KHF2) tested for the disassembly of the PIZOFs in [D6]DMSO, the combination of CsF and DCl was found to be the best. The disassembly at room temperature was fast (5–15 min), and after the addition of K2CO3 the 1H NMR data were identical to those of the diacids (=protonated linkers) dissolved in pure DMSO. This allowed for simple structure elucidation through data comparison. CsF/DCl dissolves not only PIZOFs but also the hydrolytically very stable UiO‐66.
Rapid Preparation of Multifunctional Surfaces for Orthogonal Ligation by Microcontact Chemistry
Authors: Wendeln Christian , Rinnen Stefan , Schulz Christian , Kaufmann Tobias , Arlinghaus Heinrich F. , Ravoo Bart Jan 
Published: April 2012

AbstractMicrocontact chemistry has been applied to patterned glass and silicon substrates by successive reaction of unprotected and monoprotected heterobifunctional linkers with alkene‐terminated self‐assembled monolayers (SAMs) to produce bi‐, tri‐, and tetrafunctional surfaces. Photochemical microcontact printing of an azide thiol linker followed by immobilization of an acid thiol linker on an undecenyl‐terminated SAM results in a well‐defined, micropatterned surface with terminal azide, acid, and alkene groups. Biologically relevant molecules (biotin, carbohydrates) have been selectively attached to the surface by means of orthogonal ligation chemistry, and the resulting microarrays display selective binding to fluorescently labeled proteins. An orthogonally addressable, tetrafunctional surface (azide, acid, alkene, and amine) can be prepared by an additional printing step of a tert‐butyloxycarbonyl (Boc)‐protected alkyne amine linker on the azide structures by using the copper(I)‐catalyzed azide–alkyne Huisgen cycloaddition and subsequent removal of the protective group.
Selectively Deposited Noble Metal Nanoparticles on Fe3O4/Graphene Composites: Stable, Recyclable, and Magnetically Separable Catalysts
Authors: Li Xiyan , Wang Xiao , Song Shuyan , Liu Dapeng , Zhang Hongjie 
Published: April 2012

AbstractA simple, efficient, and general approach was developed to selectively deposit noble metal (Pt, Pd, or PtPd) nanoparticles 3–5 nm in size on magnetite/graphene composites. The biomolecule L‐lysine with two kinds of functional groups (NH2 and COOH) played the key role of connecter between noble metals and Fe3O4/graphene composites. These composites were characterized by TEM, XRD, energy‐dispersive X‐ray spectroscopy, and X‐ray photoelectron spectroscopy. The results indicated that the noble metals are mostly dispersed on the magnetite surfaces of the composites. The as‐obtained composites are ideal recyclable catalysts for liquid‐phase reactions owing to their stability and efficient magnetic separation. Among these catalysts, the PtPd‐based composites exhibited the highest activity and resistance to poisoning during the catalytic reduction of 4‐nitrophenol to 4‐aminophenol by NaBH4. Such hybrid catalysts obtained by this simple, efficient method are expected to find use in industrial applications, where separation and recycling are critically required to reduce cost and waste production.
Pairwise interaction enthalpies of enantiomers of β‐amino alcohols in DMSO + H2O mixtures at 298.15 K
Authors: Liang Hongyu , Hu Xingen , Fang Guoyong , Shao Shuang , Guo Aidi , Guo Zheng 
Published: April 2012

AbstractThe dilution enthalpies of enantiomers of six β‐amino alcohols, namely (R)‐(−)‐2‐amino‐1‐propanol versus (S)‐(+)‐2‐amino‐1‐propanol, (R)‐(−)‐2‐amino‐1‐butanol versus (S)‐(+)‐2‐amino‐1‐butanol, and (R)‐(−)‐2‐amino‐1‐pentanol versus (S)‐(+)‐2‐amino‐1‐pentanol in dimethylsulfoxide (DMSO) + H2O mixtures (mass fractions of DMSO w = 0 to 0.3) have been determined respectively using an isothermal titration calorimeter (MicroCal ITC200, Northampton, MA, USA) at 298.15 K. According to the McMillan–Mayer theory, the corresponding homochiral enthalpic pairwise interaction coefficients (hXX) of the six amino alcohols have been calculated. It is found that across the whole studied composition range of mixed solvent, values of hXX for S‐enantiomer are almost universally higher than those of R‐enantiomer for each amino alcohol and that the variations of hXX depend largely on the composition of mixed solvent. The results were interpreted from the point of view of solute–solute interaction mediated by cosolvent DMSO, as well as competition equilibrium between hydrophobic–hydrophobic, hydrophilic–hydrophilic, and hydrophobic–hydrophilic interactions. Chirality 24:374–385, 2012. © 2012 Wiley Periodicals, Inc.
Bismuth Hexagons: Facile Mass Synthesis, Stability and Applications
Authors: Som Tirtha , Simo Anne , Fenger Robert , Troppenz Gerald V. , Bansen Roman , Pfänder Norbert , Emmerling Franziska , Rappich Jörg , Boeck Torsten , Rademann Klaus 
Published: April 2012

AbstractA unique direct electrodeposition technique involving very high current densities, high voltages and high electrolyte concentrations is applied for highly selective mass synthesis of stable, isolable, surfactant‐free, single‐crystalline Bi hexagons on a Cu wire at room temperature. A formation mechanism of the hexagons is proposed. The morphology, phase purity, and crystallinity of the material are well characterized by FESEM, AFM, TEM, SAED, EDX, XRD, and Raman spectroscopy. The thermal stability of the material under intense electron beam and intense laser light irradiation is studied. The chemical stability of elemental Bi in nitric acid shows different dissolution rates for different morphologies. This effect enables a second way for the selective fabrication of Bi hexagons. Bi hexagons can be oxidized exclusively to α‐Bi2O3 hexagons. The Bi hexagons are found to be promising for thermoelectric applications. They are also catalytically active, inducing the reduction of 4‐nitrophenol to 4‐aminophenol. This electrodeposition methodology has also been demonstrated to be applicable for synthesis of bismuth‐based bimetallic hybrid composites for advanced applications.
Evaluation of flow cytometric assessment of myeloid nuclear differentiation antigen expression as a diagnostic marker for myelodysplastic syndromes in a series of 269 patients
Authors: Bellos Frauke , Alpermann Tamara , Gouberman Elena , Haferlach Claudia , Schnittger Susanne , Haferlach Torsten , Kern Wolfgang 
Published: April 2012

AbstractBackground:Myeloid nuclear differentiation antigen (MNDA) is expressed in myelomonocytic cells with highest levels in mature granulocytes and monocytes. It is suggested to be expressed more weakly in patients with myelodysplastic syndromes (MDS). The analysis of MNDA therefore may improve diagnostic capabilities of multiparameter flow cytometry (MFC) in MDS.Methods:We used MFC for detection of MNDA expression in 269 patients with suspected or known MDS, acute myeloid leukemia (AML) or chronic myelomonocytic leukemia (CMML), cytopenia of unknown cause or without malignancy (negative controls). Results were compared with the diagnoses revealed by cytomorphology (CM) and cytogenetics (CG).Results:Percentages of granulocytes and monocytes with diminished MNDA expression (dimG and dimM) were higher in patients with MDS (mean ± SD, 20% ± 20%, P < 0.001 and 31% ± 24%, P < 0.001) and AML (27% ± 27%, P = 0.007 and 45% ± 31%, P = 0.001) diagnosed by CM, vs. patients without MDS (8% ± 10% and 16% ± 11%), respectively. Significant differences were also found for mean fluorescence intensity (MFI) of MNDA in monocytes which was lower in MDS (mean ± SD, 71 ± 36, P = 0.004) and AML (55 ± 39, P < 0.001) vs. no MDS samples (85 ± 28), respectively. Within patients with MDS, cases with cytogenetic aberrations showed a trend to higher %dimG (24% ± 18%, P = 0.083) compared with those without (16% ± 21%). Cut‐off values for %dimG (12%) and %dimM (22%) as well as for MFI in monocytes (72) were defined capable of discriminating between MDS and non‐MDS.Conclusion:MNDA expression in bone marrow cells can be assessed reliably by MFC and may facilitate evaluation of dyspoiesis when added to a standard MDS MFC panel. © 2012 International Clinical Cytometry Society