bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reinforcing Epoxy Polymer Composites Through Covalent Integration of Functionalized Nanotubes
Authors: Zhu J. , Peng H. , Rodriguez‐Macias F. , Margrave J. L. , Khabashesku V. N. , Imam A. M. , Lozano K. , Barrera E. V. 
Published: July 2004

AbstractStrong interfacial bonding and homogenous dispersion have been found to be necessary conditions to take full advantage of the extraordinary properties of nanotubes for reinforcement of composites. We have developed a fully integrated nanotube composite material through the use of functionalized single‐walled carbon nanotubes (SWNTs). The functionalization was performed via the reaction of terminal diamines with alkylcarboxyl groups attached to the SWNTs in the course of a dicarboxylic acid acyl peroxide treatment. Nanotube‐reinforced epoxy polymer composites were prepared by dissolving the functionalized SWNTs in organic solvent followed by mixing with epoxy resin and curing agent. In this hybrid material system, nanotubes are covalently integrated into the epoxy matrix and become part of the crosslinked structure rather than just a separate component. Results demonstrated dramatic enhancement in the mechanical properties of an epoxy polymer material, for example, 30–70 % increase in ultimate strength and modulus with the addition of only small quantities (1–4 wt.‐%) of functionalized SWNTs. The nanotube‐reinforced epoxy composites also exhibited an increased strain to failure, which suggests higher toughness.
Chain‐Length Dependence of Singlet and Triplet Exciton Formation Rates in Organic Light‐Emitting Diodes
Authors: Beljonne D. , Ye A. , Shuai Z. , Brédas J.‐L. 
Published: July 2004

AbstractThe operation and efficiencies of molecular or polymer organic light‐emitting diodes depend on the nature of the excited species that are formed. The lowest singlet and triplet excitons display different characteristics that impact on the quantum yields achievable in the devices. Here, by performing correlated quantum‐chemical calculations that account for both the electronic couplings and energetics of the charge‐recombination process from a pair of positive and negative polarons into singlet and triplet excitons, we show that the formation rates for singlet over triplet excitons vary with chain length and favor singlet excitons in longer chains. Thus, in polymer devices, the resulting singlet/triplet fraction can significantly exceed the spin‐statistical limit.
Microscopic Morphology of Polyfluorene–Poly(ethylene oxide) Block Copolymers: Influence of the Block Ratio
Authors: Surin M. , Marsitzky D. , Grimsdale A. C. , Müllen K. , Lazzaroni R. , Leclère P. 
Published: July 2004

AbstractIn this paper, we describe the synthesis and characterization of poly(9,9′‐dioctylfluorene)–poly(ethylene oxide) (PF‐PEO) block copolymers with different block ratio and molecular architectures (diblock or triblock copolymers). Tapping‐mode atomic force microscopy is used to investigate the relationship between the molecular structure and the microscopic morphology of thin deposits. Copolymers with a low average volume ratio of PEO (fEO from 0.1 to 0.3) exhibit a well‐defined organization into nanoribbons. A model of chain packing is proposed; these structures arise from the interplay of π–π interactions between conjugated PF segments and the interactions of PEO with the mica substrate surface. For copolymers with higher average volume ratio of PEO (fEO > 0.4), the organized structures disappear and lead to untextured aggregates, probably because long‐range, regular π–π stacking of the segments can no longer take place. We also observe that the nature of the solvent from which deposits are grown and the substrate polarity have a strong impact on the microscopic morphology.
Siliceous ZSM‐5 Membranes by Secondary Growth of b‐Oriented Seed Layers
Authors: Lai Z. , Tsapatsis M. , Nicolich J. P. 
Published: July 2004

AbstractA modified seeded growth procedure, which allowed us to prepare the first functional b‐oriented siliceous ZSM‐5 membrane (Z. Lai et al., Science, 2003, 300, 456), is described and discussed in detail. The procedure involves growing a b‐oriented ZSM‐5 seed monolayer into a dense b‐oriented membrane. Preservation of the orientation is achieved by enhancing the growth rate of siliceous ZSM‐5 crystals along the b‐axis using trimer‐TPAOH (bis‐N,N‐(tripropylammoniumhexamethylene) di‐N,N‐propylammonium trihydroxide) as the structure‐directing agent (SDA). Under similar synthesis conditions but using monomer‐TPAOH (tetrapropylammonium hydroxide) as the SDA for the secondary growth of the b‐oriented seed layer, two other films with mixed grain orientations, namely b&a‐ or b&a&h0h/c‐oriented ZSM‐5 membranes were obtained depending on temperature of the secondary growth. Membrane microstructures were characterized by X‐ray diffraction, pole figure analysis, scanning electron microscopy, fluorescent confocal optical microscopy, electron probe microanalysis, and X‐ray photoelectron spectroscopy. The separation performance of the three types of membranes was tested by using a mixture of xylene isomers. Significant improvement in both permeance and separation factor is achieved by the b‐oriented siliceous ZSM‐5 membrane compared to the other two types of membranes described here or other reported ZSM‐5 membranes in the literature. The permeation results indicate that the membrane performance depends strongly on membrane microstructure.
Enhancing antiretroviral therapy for human immunodeficiency virus cognitive disorders
Authors: Letendre Scott L. , McCutchan J. Allen , Childers Meredith E. , Woods Steven P. , Lazzaretto Deborah , Heaton Robert K. , Grant Igor , Ellis Ronald J. ,   the HNRC Group
Published: July 2004

AbstractThe benefits of combination antiretroviral therapy (ART) for HIV cognitive disorders vary substantially between individuals. This study evaluated whether cerebrospinal fluid (CSF) drug penetration and CSF virological suppression influence the extent of neuropsychological (NP) improvement during ART. Overall performance on a battery of NP tests administered at baseline and follow‐up (median 15 weeks) was computed by using the global deficit score (GDS) methods in 31 cognitively impaired, HIV‐infected individuals who began new ART regimens. Virological suppression (attaining undetectable viral load by RT‐PCR at follow‐up) was assessed separately for plasma and CSF. Subjects on regimens containing greater numbers of CSF‐penetrating drugs showed significantly greater reduction in CSF viral load. Subjects attaining CSF virological suppression demonstrated greater GDS improvement than those who did not (median GDS change, 0.62 vs 0.23; p = 0.01). A similar trend for plasma did not reach statistical significance (p = 0.053). NP improvement was greater in ART‐naive versus treatment‐experienced subjects. In a multivariate model (overall p = 0.0008), significant, independent predictors of GDS reduction were CSF HIV RNA suppression, baseline antiretroviral history, and their interaction. Including CSF‐penetrating drugs in the ART regimen and monitoring CSF viral load may be indicated for individuals with HIV‐associated cognitive impairment Ann Neurol 2004.
Microsmatic primates: Reconsidering how and when size matters
Authors: Smith Timothy D. , Bhatnagar Kunwar P. 
Published: July 2004

AbstractThe terms “microsmatic” and “macrosmatic” refer to species with lesser or greater levels, respectively, of olfactory function. Historically, primates are considered microsmats (olfactory sense reduced) with a concomitant increased emphasis on vision. The olfactory bulbs (forebrain centers that receive peripheral olfactory input) are proportionately smaller in primates compared to most other mammals. Similarly, the regions of the nasal cavity that are covered with olfactory epithelium (containing receptor cells) have proportionately less surface area in primates than other mammals. Thus, the generalization that primates are microsmatic is most frequently stated in terms of the proportional rather than absolute size of olfactory structures. Yet the importance of scaling to body size is unclear in regard to the chemical senses such as the olfactory or vomeronasal systems—do chemosensory structures such as olfactory bulbs and olfactory epithelium exhibit the same neural relationship to body mass that is seen for neural tissues that supply innervation to musculature or the skin? Previous studies examining neuronal density, volume, and/or surface area of the olfactory epithelium illustrate that different conclusions may be supported based on the parameter used. Plots of olfactory bulb volume versus body mass that generated for large‐scale taxonomic studies or growth studies benefit from body mass (or total brain volume) with a comparative perspective. However, our examination of proportional versus absolute measurements implies that in comparisons within taxa, body size adjustments needlessly distort the data. As a final consideration, another embryonic derivative of the nasal placode, the vomeronasal organ, may warrant consideration regarding a definition of microsomia versus macrosomia. Anat Rec (Part B: New Anat) 279B:24–31, 2004. © 2004 Wiley‐Liss, Inc.
Optimized recovery of monoclonal antibodies from transgenic goat milk by microfiltration
Authors: Baruah Gautam Lal , Belfort Georges 
Published: July 2004

AbstractThe Predictive Aggregate Transport Model for microfiltration is used in combination with optimum fluid mechanics and electrostatics to maximize recovery of a heterologous immunoglobulin (IgG) from transgenic goat milk. The optimization algorithm involved varying pH (6.8–9), transmembrane pressure (2–4.5 psi), milk feed concentration (1–2X), membrane module type (linear vs. helical design), and axial velocity (Reynolds number: 830‐1170). Operation in the pressure‐dependent regime at low uniform transmembrane pressures (≈2 psi) using permeate circulation in co‐flow, at the pI of the protein (9 in this case) was used to increase IgG recovery from less than 1% to over 95%. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and attenuated total reflection Fourier transform infrared spectroscopy of the microfiltration permeate samples confirmed that all the fat globules and most of the casein micelles were retained in the MF membrane whereas a large amount of the target IgG was transported through the membrane. Transmembrane pressure and hence permeation flux was kept low (≈15 lmh) to maximize IgG membrane transport and thus recovery, due to a sparse deposit on the membrane which facilitated high solute transport. Next, an analytical method was used to optimize the diafiltration process using the aggregate transport model, experimental target protein sieving coefficients and permeation flux (Baruah and Belfort, 2003). The methodology reported here should be generalizable to the recovery of target proteins found in other complex suspensions of biological origin using the microfiltration process. © 2004 Wiley Periodicals, Inc.
Evaluation of selectivity changes in HIC systems using a preferential interaction based analysis
Authors: Xia Fang , Nagrath Deepak , Garde Shekhar , Cramer Steven M. 
Published: July 2004

AbstractIt is well established that salt enhances the interaction between solutes (e.g., proteins, displacers) and the weak hydrophobic ligands in hydrophobic interaction chromatography (HIC) and that various salts (e.g., kosmotropes, chaotropes, and neutral) have different effects on protein retention. In this article, the solute affinity in kosmotropic, chaotropic, and neutral mobile phases are compared and the selectivity of solutes in the presence of these salts is examined. Since solute binding in HIC systems is driven by the release of water molecules, the total number of released water molecules in the presence of various types of salts was calculated using the preferential interaction theory. Chromatographic retention times and selectivity reversals of both proteins and displacers were found to be consistent with the total number of released water molecules. Finally, the solute surface hydrophobicity was also found to have a significant effect on its retention in HIC systems. © 2004 Wiley Periodicals, Inc.
Chromatofocusing of peptides and proteins using linear pH gradients formed on strong ion‐exchange adsorbents
Authors: Kang Xuezhen , Frey Douglas D. 
Published: July 2004

AbstractAlthough it is commonly believed that a column packing used for chromatofocusing must have an “even” buffering capacity in order to produce a linear pH gradient, it is demonstrated here that linear pH gradients suitable for chromatofocusing can be produced on a column packing having a minimal buffering capacity. In particular, if either a strong‐acid cation‐exchange column packing or a strong‐base anion‐exchange column packing is presaturated with either a weak acid titrated with a strong base, or a weak base titrated with a strong acid, respectively, to the initial pH, then a linear or nearly linear pH gradient can be formed using a polyampholyte elution buffer by taking advantage of the presence of small quantities of weak‐acid or weak‐base functional groups that generally exist on these types of column packings. Experimental and theoretical studies are used to demonstrate that such systems have potential advantages over traditional chromatofocusing methods in terms of the speed of the separation, the resolution achieved, and the range of applications possible. Among other techniques described, a method for separating tryptic peptides using chromatofocusing and a strong‐acid cation‐exchange column packing is demonstrated to be a useful alternative to capillary isoelectric focusing and ion‐exchange chromatography using a salt gradient for this purpose. © 2004 Wiley Periodicals, Inc.
Preparative protein purification on underivatized silica
Authors: Ghose Sanchayita , McNerney Thomas M. , Hubbard Brian 
Published: July 2004

AbstractThis article describes the use of underivatized silica gel as a preparative stationary phase for process purification of proteins. Although silica has been frequently used as a stationary phase backbone matrix, direct adsorption of proteins on underivatized silica has not been widely exploited for industrial applications. In this study an effort was made to fundamentally understand the interaction mechanisms between a protein and silica surface by using several proteins with a wide range of isoelectric points (pIs) and surface hydrophobicity. Interactions in silica were found to be largely dominated by a combination of ionic and hydrophobic forces. Accordingly, a predictive model was derived for describing linear retention of proteins on silica. Finally, a case study is described investigating the role of silica in an industrial purification process. It was found that the integration of the two modes of interaction confers silica with a unique selectivity that can be very effectively utilized in downstream bioprocessing. © 2004 Wiley Periodicals, Inc.
Determination of lipoic acid in rat plasma by LC‐MS/MS with electrospray ionization: Assay development, validation and application to a pharamcokinetic study
Authors: Trivedi Ravi Kumar , Kallem Raja Reddy , Mamidi Rao N. V. S. , Mullangi Ramesh , Srinivas Nuggehally R. 
Published: July 2004

AbstractA simple, sensitive and specific LC‐MS/MS method for the determination of lipoic acid was developed and validated over the linearity range 5–1000 ng/mL (r2 > 0.99) with 200 µL rat plasma using rosigliatzone as an internal standard (IS). The assay procedure involved a simple one‐step liquid–liquid extraction of lipoic acid and IS from plasma into ethyl acetate. The organic layer was separated and evaporated under a gentle stream of nitrogen at 40°C. The residue was reconstituted in the mobile phase and injected onto a Hichrom RPB column (4.6 × 250 mm, 5 µm). Separation of lipoic acid and IS was achieved with a mobile phase consisting of 0.05 m formic acid:acetonitrile (40:60, v/v) at a flow rate of 1.0 mL/min. The API‐3000 LC‐MS/MS was operated under the multiple reaction monitoring mode (MRM) using the electrospray ionization technique. Positive and negative ion acquisition within the same chromatographic run was used in the present method. For lipoic acid a pseudo‐molecular ion transition pair was acquired in negative polarity, whereas for IS the transition pair was acquired in positive polarity. Quantitation was determined for both analyte and IS in MRM scan mode. Absolute recovery of lipoic acid and IS was >70 and 97%, respectively. The lower limit of quantification (LLOQ) of lipoic acid was 5.0 ng/mL. The inter‐ and intra‐day precision in the measurement of quality control (QC) samples 5, 15, 400 and 800 ng/mL were in the range 2.18–5.99% relative standard deviation (RSD) and 0.93–13.77% RSD, respectively. Accuracy in the measurement of QC samples was in the range 87.40–114.40% of the nominal values. Analyte and IS were stable in the battery of stability studies, viz. bench‐top, auto‐sampler and freeze–thaw cycles. Stability of lipoic acid was established for 1 month at −80°C. The application of the assay to a pharmacokinetic study in rats confirmed the utility of the assay. Copyright © 2004 John Wiley & Sons, Ltd.
A validated HPLC determination of the ﬂavone aglycone diosmetin in human plasma
Authors: Kanaze Feras Imad , Bounartzi Melpomeni I. , Niopas Ioannis 
Published: July 2004

AbstractDiosmetin, 3′,5,7‐trihydroxy‐4′‐methoxyﬂavone, is the aglycone of the ﬂavonoid glycoside diosmin that occurs naturally in foods of plant origin. Diosmin exhibits antioxidant and anti‐inﬂammatory activities, improves venous tone and it is used for the treatment of chronic venous insufﬁciency. Diosmin is hydrolyzed by enzymes of intestinal microﬂora before absorption of its aglycone diosmetin. A speciﬁc, sensitive, precise, accurate and robust HPLC assay for the determination of diosmetin in human plasma was developed and validated. Diosmetin and the internal standard 7‐ethoxycoumarin were isolated from plasma by liquid–liquid extraction and separated on a C8 reversed‐phase column with methanol–water–acetic acid (55:43:2, v/v/v) as the mobile phase at 43°C. Peaks were monitored at 344 nm. The method was linear in the 10–300 ng/mL concentration range (r > 0.999). Recovery for diosmetin and internal standard was greater than 89.7 and 86.8%, respectively. Intra‐day and inter‐day precision for diosmetin ranged from 1.6 to 4.6 and from 2.2 to 5.3%, respectively, and accuracy was better than 97.9%. Copyright © 2004 John Wiley & Sons, Ltd.
Transition planning and recidivism among mentally ill juvenile offenders
Authors: Trupin Eric W. , Turner Aaron P. , Stewart David , Wood Peter 
Published: July 2004

AbstractObjectives:To determine the extent to which transition planning and community service would predict lower levels of recidivism among mentally ill juvenile offenders.Design:Review of legal, medical and social service records including examination of 3‐month period following community release.Participants:Juvenile offenders incarcerated for 6 months or more (N = 44) transitioning to community.Measures:Child and Adolescent Functional Assessment Scale (CAFAS), sum of different documented pre‐ and post‐release discharge planning contacts, documented community service contacts.Outcomes:Re‐offense during the first year post‐release.Results:Documented community service contacts in the 3 months following discharge were rare for mental health (20.5%), substance abuse (38.6%), financial assistance (29.5%), and school placement (34.1%). The average number of different pre‐release and post‐release discharge planning contacts was also low, M(SD)=1.86(1.68) and M(SD)= 2.34(1.71) respectively. Post‐release discharge planning and the receipt of financial assistance and mental health services were all associated with lower levels of reoffending.Conclusions:Community transition planning, including the coordination and provision of community services, is an essential component of community reintegration for juvenile offenders and is associated with lower rates of recidivism during the first year post‐discharge. Copyright © 2004 John Wiley & Sons, Ltd.
Women with co‐occurring substance use and mental disorders (COD) in the criminal justice system: a research review
Authors: Sacks JoAnn Y. 
Published: July 2004

AbstractAssociated with the dramatic increase in the numbers of women entering the criminal justice system is the recognition of the prominent role of co‐occurring substance use and mental disorders (COD) in the lives of female offenders. This article reviews current research examining the prevalence and range of COD among female offenders, the variety of psychosocial problems faced by the female offender with COD, and the multiple treatment needs of women with COD who are under criminal justice supervision. Women with COD can enter the criminal justice system at several different points and, because both substance use and mental disorders carry significant risk of relapse, effective treatment approaches must address both disorders. The paper concludes with a discussion of several important treatment issues and provides suggestions regarding an agenda for future treatment and research. Copyright © 2004 John Wiley & Sons, Ltd.
Computer‐based laboratory for data communications and computer networking
Authors: Kayssi Ayman , Sharafeddine Sanaa , Karaki Houda 
Published: July 2004

AbstractData communications and computer networking (DCCN) has established itself as an essential part of most computer science and engineering curricula, usually in the form of courses and/or laboratories. For reliable training in this area, this study presents a series of 10 experiments that serve as a complete laboratory course in DCCN. The prominent benefit of this laboratory set is that it uses available UNIX workstations where networking is simulated using software; this overcomes the obstacle of unavailable or expensive hardware and communication resources. The experiments presented here cover all layers, except the physical layer, of the Open Systems Interconnection (OSI) model. In addition to introducing the student to this wide‐ranging subject matter, the laboratory set enhances his/her programming skills. This is accomplished by introducing the UNIX programming environment and using it to carry out the experiments, starting with editing and compiling simple programs, and ending with implementing advanced client‐server applications. © 2004 Wiley Periodicals, Inc. Comput Appl Eng Educ 12: 84–97, 2004; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20002
A prelab tutoring system for Strength of Materials experiment
Authors: Chen Chuin‐Shan , Hsieh Shang‐Hsien , Chuang Sheng‐Chin , Lin Shiu‐Shin 
Published: July 2004

AbstractWe aim to resolve a long‐standing problem on requiring students to study how to maneuver experiments before they actually conduct them in a laboratory. A prelab tutoring system for the Strength of Materials experiment is prototyped from desired outcomes. The tutoring system utilizes a game‐like environment to engage students in learning. Consisting of highly interactive contents made by scalable vector graphics (SVGs), the system helps students to get acquainted with laboratory instruments as well as experimental procedures. The effectiveness and efficiency of the system have been confirmed through a survey among students. © 2004 Wiley Periodicals, Inc. Comput Appl Eng Educ 12: 98–105, 2004; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20004