bluuebunny/crossref_metadata_2025 huggingface dataset:
Early adolescent pregnancy increases risk of incident HIV infection in the Eastern Cape, South Africa: a longitudinal study
Authors: Christofides Nicola J , Jewkes Rachel K , Dunkle Kristin L , Nduna Mzikazi , Shai Nwabisa Jama , Sterk Claire
Published: March 2014

Introduction

Adolescents having unprotected heterosexual intercourse are at risk of HIV infection and unwanted pregnancy. However, there is little evidence to indicate whether pregnancy in early adolescence increases the risk of subsequent HIV infection. In this paper, we tested the hypothesis that adolescent pregnancy (aged 15 or younger) increases the risk of incident HIV infection in young South African women.

Methods

We assessed 1099 HIV‐negative women, aged 15–26 years, who were volunteer participants in a cluster‐randomized, controlled HIV prevention trial in the predominantly rural Eastern Cape province of South Africa. All of these young women had at least one additional HIV test over two years of follow‐up. Outcomes were HIV incidence rates per 100 person years and HIV incidence rate ratios (IRRs) estimated by Poisson multivariate models. Three pregnancy categories were created for the Poisson model: early adolescent pregnancy (a first pregnancy at age 15 years or younger); later adolescent pregnancy (a first pregnancy at age 16 to 19 years); and women who did not report an adolescent pregnancy. Models were adjusted for study design, age, education, time since first sexual experience, socio‐economic status, childhood trauma and herpes simplex virus type 2 infection.

Results

HIV incidence rates were 6.0 per 100 person years over two years of follow‐up. The adjusted IRR was 3.02 (95% CI 1.50–6.09) for a pregnancy occurring at age 15 or younger. Women with pregnancies occurring between 16 and 19 years of age did not have a higher incidence of HIV (IRR 1.08; 95% CI 0.64–1.84). Early adolescent pregnancies were associated with higher partner numbers and a greater age difference with partners.

Conclusions

Early adolescent pregnancies increase the incidence of HIV among South African women. The higher risk is associated with sexual risk behaviours such as higher partner numbers and a greater age difference with partners rather than a biological explanation of hormonal changes during pregnancy.
ErbB expressing Schwann cells control lateral line progenitor cells via non-cell-autonomous regulation of Wnt/β-catenin
Authors: Lush Mark E , Piotrowski Tatjana
Published: March 2014

Proper orchestration of quiescence and activation of progenitor cells is crucial during embryonic development and adult homeostasis. We took advantage of the zebrafish sensory lateral line to define niche-progenitor interactions to understand how integration of diverse signaling pathways spatially and temporally regulates the coordination of these processes. Our previous studies demonstrated that Schwann cells play a crucial role in negatively regulating lateral line progenitor proliferation. Here we demonstrate that ErbB/Neuregulin signaling is not only required for Schwann cell migration but that it plays a continued role in postmigratory Schwann cells. ErbB expressing Schwann cells inhibit lateral line progenitor proliferation and differentiation through non-cell-autonomous inhibition of Wnt/β-catenin signaling. Subsequent activation of Fgf signaling controls sensory organ differentiation, but not progenitor proliferation. In addition to the lateral line, these findings have important implications for understanding how niche-progenitor cells segregate interactions during development, and how they may go wrong in disease states.
Structural basis of GSK-3 inhibition by N-terminal phosphorylation and by the Wnt receptor LRP6
Authors: Stamos Jennifer L , Chu Matthew Ling-Hon , Enos Michael D , Shah Niket , Weis William I
Published: March 2014

Glycogen synthase kinase-3 (GSK-3) is a key regulator of many cellular signaling pathways. Unlike most kinases, GSK-3 is controlled by inhibition rather than by specific activation. In the insulin and several other signaling pathways, phosphorylation of a serine present in a conserved sequence near the amino terminus of GSK-3 generates an auto-inhibitory peptide. In contrast, Wnt/β-catenin signal transduction requires phosphorylation of Ser/Pro rich sequences present in the Wnt co-receptors LRP5/6, and these motifs inhibit GSK-3 activity. We present crystal structures of GSK-3 bound to its phosphorylated N-terminus and to two of the phosphorylated LRP6 motifs. A conserved loop unique to GSK-3 undergoes a dramatic conformational change that clamps the bound pseudo-substrate peptides, and reveals the mechanism of primed substrate recognition. The structures rationalize target sequence preferences and suggest avenues for the design of inhibitors selective for a subset of pathways regulated by GSK-3.
Cortical regulation of cell size by a sizer cdr2p
Authors: Pan Kally Z , Saunders Timothy E , Flor-Parra Ignacio , Howard Martin , Chang Fred
Published: March 2014

Cells can, in principle, control their size by growing to a specified size before commencing cell division. How any cell actually senses its own size remains poorly understood. The fission yeast Schizosaccharomyces pombe are rod-shaped cells that grow to ∼14 µm in length before entering mitosis. In this study, we provide evidence that these cells sense their surface area as part of this size control mechanism. We show that cells enter mitosis at a certain surface area, as opposed to a certain volume or length. A peripheral membrane protein kinase cdr2p has properties of a dose-dependent ‘sizer’ that controls mitotic entry. As cells grow, the local cdr2p concentration in nodes at the medial cortex accumulates as a measure of cell surface area. Our findings, which challenge a previously proposed pom1p gradient model, lead to a new model in which cells sense their size by using cdr2p to probe the surface area over the whole cell and relay this information to the medial cortex.
15-µm-pitch Cu/Au interconnections relied on self-aligned low-temperature thermosonic flip-chip bonding technique for advanced chip stacking applications
Authors: Tung Bui Thanh , Kato Fumiki , Watanabe Naoya , Nemoto Shunsuke , Kikuchi Katsuya , Aoyagi Masahiro
Published: March 2014

In this paper, we report the development of reliable fine-pitch micro bump interconnections that used a high-precision room-temperature bonding approach. The accuracy of the bonding process is improved by modifying conventional bump/planar-bonding-pad interconnections to form self-aligned micro bumps/truncated inverted pyramid (TIP) bonding pads, i.e., misalignment self-correction elements (MSCEs). Thermosonic flip-chip bonding (FCB) is utilized to form reliable bonds between these MSCEs at acceptable low temperatures. By applying the proposed bonding approach, the demonstration of fine-pitch Cu bump to Au bonding pad interconnects chip stacking has been realized. Microstructure analyses reveal that 15-µm-pitch micro bump joints are fabricated at room temperature.
Effects of abnormal cell-to-cell interference on p-type floating gate and control gate NAND flash memory
Authors: Kim Yong Jun , Kang Jun Geun , Lee Byungin , Cho Gyu-Seog , Park Sung-Kye , Choi Woo Young
Published: March 2014

Abnormal cell-to-cell interference occurring in NAND flash memory has been investigated. In the case of extremely downscaled NAND flash memory, cell-to-cell interference increases abnormally. The abnormal cell-to-cell interference has been observed in a p-type floating gate (FG)/control gate (CG) cells for the first time. It has been found that the depletion region variation leads to the abnormal cell-to-cell interference. The depletion region variation of FG and CG is determined by state of neighbor cells. The depletion region variation affects CG-to-FG coupling capacitance and threshold voltage variation (ΔV
T). Finally, it is observed that there is a symmetrical relationship between n- and p-type FG/CG NAND flash memory in terms of cell-to-cell interference.
Analysis of stability improvement in ZnO thin film transistor with dual-gate structure under negative bias stress
Authors: Yun Ho-Jin , Kim Young-Su , Jeong Kwang-Seok , Kim Yu-Mi , Yang Seung-dong , Lee Hi-Deok , Lee Ga-Won
Published: March 2014

In this study, we fabricated dual-gate zinc oxide thin film transistors (ZnO TFTs) without additional processes and analyzed their stability characteristics under a negative gate bias stress (NBS) by comparison with conventional bottom-gate structures. The dual-gate device shows superior electrical parameters, such as subthreshold swing (SS) and on/off current ratio. NBS of V
GS = −20 V with V
DS = 0 was applied, resulting in a negative threshold voltage (V
th) shift. After applying stress for 1000 s, the V
th shift is 0.60 V in a dual-gate ZnO TFT, while the V
th shift is 2.52 V in a bottom-gate ZnO TFT. The stress immunity of the dual-gate device is caused by the change in field distribution in the ZnO channel by adding another gate as the technology computer aided design (TCAD) simulation shows. Additionally, in flicker noise analysis, a lower noise level with a different mechanism is observed in the dual-gate structure. This can be explained by the top side of the ZnO film having a larger crystal and fewer grain boundaries than the bottom side, which is revealed by the enhanced SS and XRD results. Therefore, the improved stability of the dual-gate ZnO TFT is greatly related to the E-field cancellation effect and crystal quality of the ZnO film.
Normally-off type nonvolatile static random access memory with perpendicular spin torque transfer-magnetic random access memory cells and smallest number of transistors
Authors: Tanaka Chika , Abe Keiko , Noguchi Hiroki , Nomura Kumiko , Ikegami Kazutaka , Fujita Shinobu
Published: March 2014

In this paper, we present a novel nonvolatile-random access memory (RAM) cell design based on a “normally-off memory architecture” using a perpendicular spin torque transfer-magnetic random access memory (STT-MRAM) based on a four-transistors static random access memory (SRAM) in order to reduce the operating power of mobile processors. After the cell design concept and basic operation are proposed, a stable and reliable operation for read/write is confirmed by circuit simulation.
Evaluations of Pr3+ doped KY3F10 scintillator
Authors: Yanagida Takayuki , Fujimoto Yutaka , Fukuda Kentaro
Published: March 2014

Pr3+ 1 and 5% doped KY3F10 (Pr:KYF) scintillators were prepared by Tokuyama to examine optical and scintillation characteristics. In X-ray induced radioluminescence spectra, Pr3+ 5d–4f emission at 280 nm and 4f–4f emission with several lines at visible wavelength were observed. In pulse height measurements with PMT R7600-200, 241Am 5.5 MeV α-ray was irradiated to samples. As a result, Pr 1 and 5% doped KYF exhibited 700 and 300 photons/5.5 MeV-α, respectively. The fast component of the scintillation decay time constants turned out to be 4.5 and 2.5 ns for Pr 1 and Pr 5% doped samples, respectively.
Forecasting air traffic volumes using smoothing techniques
Authors: Önder Emrah , Kuzu Sultan
Published: March 2014

For many years, researchers have been using statistical tools to estimate parameters of macroeconomic models. Forecasting plays a major role in logistic planning and it is an essential analytical tool in countries’ air traffic strategies. In recent years, researchers are developing new techniques for estimation. In particular, this research focuses on the application of smoothing techniques and estimation of air traffic volume. In this study four air traffic indicators including total passenger traffic, total cargo traffic, total flight traffic and commercial flight traffic were used for forecasting. Also seasonal effects of these parameters were investigated. As analysis tools, classical time series forecasting methods such as moving averages, exponential smoothing, Brown’s single parameter linear exponential smoothing, Brown’s second-order exponential smoothing, Holt’s two parameter linear exponential smoothing and decomposition methods applied to air traffic volume data between January 2007 and May 2013. The study focuses mainly on the applicability of Traditional Time Series Analysis (Smoothing & Decomposition Techniques). To facilitate the presentation, an empirical example is developed to forecast Turkey’s four important air traffic parameters. Time Series statistical theory and methods are used to select an adequate technique, based on residual analysis.
Incidental Findings on Simulation CT Images for Adjuvant Radiotherapy in Breast Cancer Patients
Authors: Park Jun Su , Choi Doo Ho , Huh Seung Jae , Park Won , Nam Seok Jin , Lee Jeong Eon , Kil Won Ho , Lee Kyung Soo
Published: March 2014

We designed this study to evaluate the incidence of incidental findings on computed tomography (CT) scan implemented as simulation for adjuvant radiotherapy in breast cancer patients and to emphasize the need for careful review of simulation CT images before planning radiotherapy. A Resident and attending radiation oncologists retrospectively reviewed the medical records and simulation CT images of 776 patients treated with adjuvant radiotherapy at Samsung Medical Center during 2008. Previously undetected abnormal findings on simulation CT images were defined as incidental findings and interpreted by diagnostic radiologist. If the incidental findings required further evaluation or follow-up, they were defined as indeterminate findings. If subsequent cancers were diagnosed according incidental findings, they were defined as malignancy-related findings. There were 81 indeterminate findings (10.8%) including thyroid nodule, solitary pulmonary nodule, mediastinal lymph node, supraclavicular or axillary lymph node. Among them, there were nine malignancy-related findings (1.3%), including four thyroid cancers, three lung metastases, one primary lung cancer, and one axillary lymph node recurrence. The incidence of incidental findings in this study was low, but some of the findings were related to malignancy. Radiation oncologists should be alert to incidental findings on simulation CT, and incidental findings should be evaluated by diagnostic radiologists.
Aerosol impacts on drizzle properties in warm clouds from ARM Mobile Facility maritime and continental deployments
Authors: Mann Julian A. L. , Christine Chiu J. , Hogan Robin J. , O'Connor Ewan J. , L'Ecuyer Tristan S. , Stein Thorwald H. M. , Jefferson Anne
Published: March 2014

We have extensively evaluated the response of cloud base drizzle rate (Rcb; mm d−1) in warm clouds to liquid water path (LWP; g m−2) and to cloud condensation nuclei (CCN) number concentration (NCCN; cm−3), an aerosol proxy. This evaluation is based on a 19 month long data set of Doppler radar, lidar, microwave radiometers, and aerosol observing systems from the Atmospheric Radiation Measurement (ARM) Mobile Facility deployments at the Azores and in Germany. Assuming 0.55% supersaturation to calculate NCCN, we found a power law , indicating that Rcb decreases by a factor of 2–3 as NCCN increases from 200 to 1000 cm−3 for fixed LWP. Additionally, the precipitation susceptibility to NCCN ranges between 0.5 and 0.9, in agreement with values from simulations and aircraft measurements. Surprisingly, the susceptibility of the probability of precipitation from our analysis is much higher than that from CloudSat estimates but agrees well with simulations from a multiscale high‐resolution aerosol‐climate model. Although scale issues are not completely resolved in the intercomparisons, our results are encouraging, suggesting that it is possible for multiscale models to accurately simulate the response of LWP to aerosol perturbations.
Mechanisms and cross sections for water desorption from a lunar impact melt breccia
Authors: DeSimone Alice J. , Orlando Thomas M.
Published: March 2014

Desorption of H2O (ν = 0) following 157‐nm irradiation of amorphous solid water on a lunar impact melt breccia was measured with resonance‐enhanced multiphoton ionization. Photofragments of vibrationally excited water were detected with nonresonant ionization. The average cross section for H2O (ν = 0) removal and destruction at 0.1 Langmuir (1 L = 10−6 Torr∙s) H2O exposure was measured to be (7.1 ± 1.9) × 10−19 cm2. Cross sections were also measured at 0.3, 1, 5, and 10 L exposures. Because these cross sections increase drastically with decreasing water coverage, water is not expected to remain intact as H2O on the sunlit lunar surface. Instead, photons are likely to cause H2O to desorb or dissociate. The OH+ fragment of H2O (ν*) increased in intensity with increasing irradiation as hydroxyl groups built up on the surface and then recombined. The OH+ signal eventually began to decrease after a dose of 5 × 1018 photons cm−2. Under these conditions, the cross section for H2O (ν*) photodesorption was measured to be 6.4 × 10−20 cm2 for an initial exposure of 5 L H2O.
Highly Efficient Multifunctional Supramolecular Gene Carrier System Self‐Assembled from Redox‐Sensitive and Zwitterionic Polymer Blocks
Authors: Wen Yuting , Zhang Zhongxing , Li Jun
Published: March 2014

It has been a challenge to incorporate multiple features into a single gene carrier system to overcome numerous hurdles during the gene delivery. Herein, a supramolecular approach for building a multifunctional gene carrier system is demonstrated with the functions of disulfide bond based reduction‐responsive degradation and zwitterionic phosphorylcholine based extracellular stabilization and favorable cellular uptake. The gene carrier system is self‐assembled from two molecular building blocks: one host polymer, which is a redox‐sensitive β‐cyclodextrin based cationic star polymer, and one guest polymer, which is adamantyl end capped zwitterionic phosphorylcholine based polymer. The host and guest polymers self‐assemble to integrate multiple functions into one system, based on the host‐guest interaction between β‐cyclodextrin and adamantyl moieties. With the rational designs of both building blocks, the supramolecular gene carrier system possesses excellent protein stability, serum tolerance, cellular uptake and intracellular DNA release properties, and also low cytotoxicity. These features work simultaneously to achieve exceptionally high gene transfection efficiency, which is proven in MCF‐7 cell cultures using luciferase and green fluorescence protein reporter genes. Finally, the supramolecular gene carrier is applied to deliver the therapeutic p53 anti‐cancer gene in MCF‐7 cells, showing great potential for cancer gene therapy application.
Single‐Crystal‐to‐Single‐Crystal Transformation of a Europium(III) Metal–Organic Framework Producing a Multi‐responsive Luminescent Sensor
Authors: Song Xue‐Zhi , Song Shu‐Yan , Zhao Shu‐Na , Hao Zhao‐Min , Zhu Min , Meng Xing , Wu Lan‐Lan , Zhang Hong‐Jie
Published: March 2014

A sensor with a red‐emission signal is successfully obtained by the solvothermal reaction of Eu3+ and heterofunctional ligand bpydbH2 (4,4′‐(4,4′‐bipyridine‐2,6‐diyl) dibenzoic acid), followed by terminal‐ligand exchange in a single‐crystal‐to‐single‐crystal transformation. As a result of treatments both before and after the metal–organic framework formation, accessible Lewis‐base sites and coordinated water molecules are successfully anchored onto the host material, and they act as signal transmission media for the recognition of analytes at the molecular level. This is the first reported sensor based on a metal–organic framework (MOF) with multi‐responsive optical sensing properties. It is capable of sensing small organic molecules and inorganic ions, and unprecedentedly it can discriminate among the homologues and isomers of aliphatic alcohols as well as detect highly explosive 2,4,6‐trinitrophenol (TNP) in water or in the vapor phase. This work highlights the practical application of luminescent MOFs as sensors, and it paves the way toward other multi‐responsive sensors by demonstrating the incorporation of various functional groups into a single framework.
Oxygen Ion Diffusion and Surface Exchange Properties of the α‐ and δ‐phases of Bi2O3
Authors: Bayliss Ryan D. , Cook Stuart N. , Kotsantonis Sakis , Chater Richard J. , Kilner John A.
Published: March 2014

Fast oxide ion conduction is a highly desirable property for materials in a wide range of applications. The fastest reported ionic conductor, representing the current state of the art and an oft‐proposed effective limit of oxide ion conductivity, is the high temperature fluorite‐structured δ phase of Bi2O3. Here, the ionic nature of this conduction is, for the first time, directly determined through oxygen tracer diffusion measurements. This phase also presents a remarkably high oxygen surface exchange coefficient, competitive with the highest performance solid oxide fuel cell (SOFC) cathodes yet counterintuitively in a material with negligible electronic conduction. The low temperature α‐Bi2O3 polymorph is also investigated, revealing a remarkable drop in diffusivity of over 7 orders of magnitude with a temperature drop of just ≈150 °C. Surprisingly, the diffusion studies also reveal a secondary, significantly faster migration pathway in the α phase. This is attributed to grain boundary conduction and shown to be 3–4 orders of magnitude higher than in the bulk. This previously unobserved property could present an exciting opportunity to tailor ionic conductivity levels through manipulating microstructure down to the nanoscale.
Tailoring D‐Amino Acid Oxidase from the Pig Kidney to R‐Stereoselective Amine Oxidase and its Use in the Deracemization of α‐Methylbenzylamine
Authors: Yasukawa Kazuyuki , Nakano Shogo , Asano Yasuhisa
Published: March 2014

The deracemization of racemic amines to yield enantioenriched amines using S‐stereoselective amine oxidases (AOx) has recently been attracting attention. However, R‐stereoselective AOx that are suitable for deracemization have not yet been identified. An R‐stereoselective AOx was now evolved from porcine kidney D‐amino acid oxidase (pkDAO) and subsequently use for the deracemization of racemic amines. The engineered pkDAO, which was obtained by directed evolution, displayed a markedly changed substrate specificity towards R amines. The mutant enzyme exhibited a high preference towards the substrate α‐methylbenzylamine and was used to synthesize the S amine through deracemization. The findings of this study indicate that further investigations on the structure–activity relationship of AOx are warranted and also provide a new method for biotransformations in organic synthesis.
Highly Active Bidirectional Electron Transfer by a Self‐Assembled Electroactive Reduced‐Graphene‐Oxide‐Hybridized Biofilm
Authors: Yong Yang‐Chun , Yu Yang‐Yang , Zhang Xinhai , Song Hao
Published: March 2014

Low extracellular electron transfer performance is often a bottleneck in developing high‐performance bioelectrochemical systems. Herein, we show that the self‐assembly of graphene oxide and Shewanella oneidensis MR‐1 formed an electroactive, reduced‐graphene‐oxide‐hybridized, three‐dimensional macroporous biofilm, which enabled highly efficient bidirectional electron transfers between Shewanella and electrodes owing to high biomass incorporation and enhanced direct contact‐based extracellular electron transfer. This 3D electroactive biofilm delivered a 25‐fold increase in the outward current (oxidation current, electron flux from bacteria to electrodes) and 74‐fold increase in the inward current (reduction current, electron flux from electrodes to bacteria) over that of the naturally occurring biofilms.
Iron Cyclopentadienone Complexes: Discovery, Properties, and Catalytic Reactivity
Authors: Quintard Adrien , Rodriguez Jean
Published: March 2014

Iron cyclopentadienone complexes have recently received particular attention in organic chemistry. This is due to their easy synthesis from simple and cheap materials, air–water stability, and most importantly for their unique catalytic features arising from the presence of a non‐innocent ligand, triggering powerful redox properties. Herein we discuss the properties of such complexes from synthetic and mechanistic points of view, and their applications in original redox‐neutral transformations in both racemic and enantioselective series.
A New Pathway of DNA G‐Quadruplex Formation
Authors: Čeru Slavko , Šket Primož , Prislan Iztok , Lah Jurij , Plavec Janez
Published: March 2014

A new folding intermediate of Oxytricha nova telomeric Oxy‐1.5 G‐quadruplex was characterized in aqueous solution using NMR spectroscopy, native gel electrophoresis, thermal differential spectra (TDS), CD spectroscopy, and differential scanning calorimetry (DSC). NMR experiments have revealed that this intermediate (i‐Oxy‐1.5) exists in two symmetric bimolecular forms in which all guanine bases are involved in GG N1‐carbonyl symmetric base pairs. Kinetic analysis of K+‐induced structural transitions shows that folding of Oxy‐1.5 G‐quadruplex from i‐Oxy‐1.5 is much faster and proceeds through less intermediates than folding from single strands. Therefore, a new folding pathway of Oxy‐1.5 G‐quadruplex is proposed. This study provides evidence that G‐rich DNA sequences can self‐assemble into specific pre‐organized DNA structures that are predisposed to fold into G‐quadruplex when interacting with cations such as potassium ions.
Amide Synthesis by Nucleophilic Attack of Vinyl Azides
Authors: Zhang Feng‐Lian , Wang Yi‐Feng , Lonca Geoffroy Hervé , Zhu Xu , Chiba Shunsuke
Published: March 2014

A method for the synthesis of amide‐containing molecules was developed using vinyl azides as an enamine‐type nucleophile towards carbon electrophiles, such as imines, aldehydes, and carbocations that were generated from alcohols in the presence of BF3⋅OEt2. After nucleophilic attack of the vinyl azide, a substituent of the resulting iminodiazonium ion intermediate migrates to form a nitrilium ion, which is hydrolyzed to afford the corresponding amide.
A Volatile Lactone of Hymenoscyphus pseudoalbidus, Pathogen of European Ash Dieback, Inhibits Host Germination
Authors: Citron Christian A. , Junker Corina , Schulz Barbara , Dickschat Jeroen S.
Published: March 2014

The largely unknown secondary metabolism of the plant pathogenic fungus Hymenoscyphus pseudoalbidus was investigated by use of the CLSA method. A set of volatile lactones was identified by GC/MS. The lactones were synthesized and used in bioassays in which one of the compounds was found to be a strong germination inhibitor for ash seeds, causing necroses in the plant tissue.
Fabrication of natural cellulose microspheres via electrospraying from NaOH/Urea aqueous system
Authors: Wu Weibing , Gu Jun , Zhou Guancheng , Zhang Lei , Gong Murong , Dai Hongqi
Published: March 2014

Regenerated cellulose microspheres (RCM) with controllable sizes and architectures are prepared via electrospraying from environmental‐friendly NaOH/Urea aqueous system. The particle size and shape of RCM is mainly dependent on the interplay among the electrical force, surface tension, and viscous force. Particle size can be reduced to a certain extent by increasing voltage and decreasing surface tension, electrode spacing, solution concentration, degree of polymerization, and flow rate. The deformation of droplets, which is peculiarly prone to occur for low viscosity and long electrode spacing, results in elongated spheres, tear‐shaped particles, wedge‐shaped particles, and banding shaped particles besides micorspheres. The sophericity and uniformity of particles generally become worse as a result of the deformation of droplets. RCM possess good porosity and large specific surface area after regeneration. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40656.
A Crucial Role of L‐Selectin in C Protein–Induced Experimental Polymyositis in Mice
Authors: Oishi Kyosuke , Hamaguchi Yasuhito , Matsushita Takashi , Hasegawa Minoru , Okiyama Naoko , Dernedde Jens , Weinhart Marie , Haag Rainer , Tedder Thomas F. , Takehara Kazuhiko , Kohsaka Hitoshi , Fujimoto Manabu
Published: March 2014

Objective

To investigate the role of adhesion molecules in C protein–induced myositis (CIM), a murine model of polymyositis (PM).

Methods

CIM was induced in wild‐type mice, L‐selectin–deficient (L‐selectin−/−) mice, intercellular adhesion molecule 1 (ICAM‐1)–deficient (ICAM‐1−/−) mice, and mice deficient in both L‐selectin and ICAM‐1 (L‐selectin−/−ICAM‐1−/− mice). Myositis severity, inflammatory cell infiltration, and messenger RNA expression in the inflamed muscles were analyzed. The effect of dendritic polyglycerol sulfate, a synthetic inhibitor that suppresses the function of L‐selectin and endothelial P‐selectin, was also examined.

Results

L‐selectin−/− mice and L‐selectin−/−ICAM‐1−/− mice developed significantly less severe myositis compared to wild‐type mice, while ICAM‐1 deficiency did not inhibit the development of myositis. L‐selectin−/− mice that received wild‐type T cells developed myositis. Treatment with dendritic polyglycerol sulfate significantly diminished the severity of myositis in wild‐type mice compared to treatment with control.

Conclusion

These data indicate that L‐selectin plays a major role in the development of CIM, whereas ICAM‐1 plays a lesser role, if any, in the development of CIM. L‐selectin–targeted therapy may be a candidate for the treatment of PM.
The information journey of marketing professionals: Incorporating work task‐driven information seeking, information judgments, information use, and information sharing
Authors: Du Jia Tina
Published: March 2014

Marketing professionals' work activities are heavily reliant on access to and the use of large amounts of quality information. This study aims to examine the information journey experienced by marketing professionals, including task‐driven information seeking, information judgments, information use, and information sharing, from a more contextualized and holistic viewpoint. The information journey presents a more comprehensive picture of user–information interaction than is usually offered in the literature. Using a diary method and post‐diary in‐depth interviews, data consisting of 1,198 diary entries relating to 101 real work tasks were collected over a period of 5 work days. The data were used to ascertain characteristics of the stages of marketing professionals' information journeys as well as the relationships between them. Five stages of the information journey, including determining the need for work task‐generated information, seeking such information, judging and evaluating the information found, making sense of and using the obtained information, and sharing the obtained or assembled information, were identified. The information journey also encompassed types of gaps and gap‐bridge techniques that occurred during information seeking and use. Based on the empirical findings, an information journey model was developed. The implications for information systems design solutions that enable different stages of the information journey to be linked together are also discussed.
Mass Spectrometric Investigation of the Reaction between Oxygen Atoms and Carbonyl Sulfide
Authors: Sullivan J. O. , Warneck P.
Published: March 2014

The reaction of oxygen atoms and carbonyl sulfide has been investigated in conjunction with a fast flow system. The following predominant reactions have been found to occur in the early stage,

magnified image

The rate constant at room temperature associated with the first reaction was determined to be k1 = 0.91 ± 0.14 · 10−14 cc/molec. sec and that of the second reaction was estimated as k5 = 4.3 · 10−12 cc/molec. sec. The implications of the chemistry of SO radicals are discussed.
Über den Einfluß von Edelgasen auf die Strahlenchemie des Äthans
Authors: Bünau Ginther
Published: March 2014

Bei der γ‐Radiolyse von Äthan in Gegenwart eines etwa 25fachen Überschusses an den Edelgasen Argon, Krypton und Xenon entstehen Radiolyseprodukte mit G‐Werten von der gleichen Größenordnung wie bei der Radiolyse von reinem Äthan. Aus diesen G‐Werten lassen sich die Wirkungsgrade der Sensibilisierung durch Edelgas zu ζAr und ζKr ã 1, ζXe ã 0,53 bestimmen. Das mögliche Eingreifen der Edelgasionen in den chemischen Relaismechanismus der Energieübertragung wird diskutiert.
Untersuchung des Reaktionsablaufs in fetten Kohlenwasserstoff‐Sauerstoff‐Flammen II. Versuche an rußenden Acetylen‐Sauerstoff‐Flammen bei niedrigem Druck
Authors: Homann K. H. , Gg. Wagner H.
Published: March 2014

Der Vorgang der Rußbildung wird an fetten, vorgemischten Acetylen‐Sauerstoff‐Flammen untersucht, die als flache Flammen bei niedrigem Druck brennen. Zur Analyse der in der Reaktionszone auftretenden gasförmigen Zwischen‐ und Endprodukte werden Proben aus der Flamme über ein Molekularstrahlsystem direkt in die Ionenquelle eines Massenspektrometers gesaugt. Dabei können wegen der weitgehenden Ausschaltung von Wandeinflüssen auch Radikale und andere instabile Zwischenprodukte bestimmt werden. Proben von Rußteilchen lassen sich mittels des gleichen Absaugsystems auf geeigneten Objektträgern auffangen und im Elektronenmikroskop auf ihre Größenverteilung und relative Anzahl in verschiedenen Höhen der Flamme analysieren. Eigenschaften des Absaugsystems und der Einfluß der Sonde auf die Flamme werden beschrieben.

Die Bedingungen der Bildung von Polyacetylenen sowie deren Konzentrationen im Gleichgewicht unter‐einander und mit Acetylen werden untersucht und ihre Rolle bei der nachfolgenden Bildung von Ruß diskutiert. Versuche, bei denen zusätzlich Brennstoff von außen in die Flamme injiziert wurde, zeigen, daß die in der Oxydationszone gebildeten Radikale Einfluß auf die später einsetzende Rußbildung haben und daß diese auf der in der ungestörten Flamme zur Verfügung stehenden Meßstrecke noch nicht als abgeschlossen betrachtet werden kann.
Untersuchung des Reaktionsablaufs in fetten Kohlenwasserstoff‐Sauerstoff‐Flammen III. Optische Untersuchungen an rußenden Flammen
Authors: Bonne U. , Gg. Wagner H.
Published: March 2014

Gleichzeitig mit den in Teil II [1] beschriebenen massenspektrometrischen Messungen über die Rußbildung in flachen Flammen bei niedrigen Drucken wurden spektroskopische Untersuchungen an diesen Flammen ausgeführt. Es wurde die Emission der Radikale C2, CH und OH, der Temperaturverlauf und die OH‐Radikal‐Konzentration innerhalb der Reaktionszone in Abhängigkeit von der Zusammensetzung des Frischgases gemessen. Daneben wurde die Rußmenge vorwiegend durch ihre Absorption bestimmt. Der Verlauf der Rußteilchengröße konnte optisch aus der Differenz von Gas‐ und Teilchentemperatur gewonnen werden.

Ferner wurde der Einfluß der Versuchsbedingungen auf die Menge des gebildeten Rußes untersucht.
Etude de la Germination Transitoire en Milieu Condensé
Authors: Gindt R. , Kern R.
Published: March 2014

En solution aqueuse sursaturée, les halogénures alcalins présentent une courbe de cristallisation M(t) à long palier initial tL (temps de latence). En décomposant le phénomène deux parties, fréquence de germination J(t) et croissance m(t) d'un germe critique, on peut déduire la courbe J (t) des courbes expérimentales M (t). La forme de J (t) montre que le régime stationnaire de germination ne s'établit que très lentement. La théorie de la germination transitoire de Frenkel‐Zeldovich jointe à celle de Volmer‐Becker‐Döring, permet d'interpréter ces résultats. Le temps de relaxation du phénomene transitoire serait dû au fait que le milieu est condensé; sa grande variation avec la sursaturation serait liée au phénomène de germination bidimensionnelle.
Über den Mechanismus der Chemilumineszenz von Phthalhydrazid
Authors: Stauff Joachim , Hartmann Gerhard
Published: March 2014

Der Mechanismus der Chemilumineszenz der Reaktion zwischen Phthalhydrazid und H2O2, die durch Cu2+ katalysiert wird, wurde durch reaktionskinetische Analyse des zeitlichen Ablaufs der Leuchtintensität und der Sauerstoffentwicklung sowie durch Aufnahme von Differenz‐Absorptionsspektren weiter aufzuklären versucht.

Durch Lösen des Geschwindigkeitsgleichungssystems der katalysierten Reaktion mit einem Analogrechner konnte ein Reaktionsschema aufgestellt werden, das die Reaktion zwischen einem um 2 Elektronen ärmeren spektroskopisch nachweisbaren Oxydationsprodukt des Phthalhydrazids und H2O2 als geschwindigkeitsbestimmend für die Anregung zum emissionsfähigen Zustand fordert. Aus dem Ablauf der nicht katalysierten Reaktion, der Hemmbarkeit der Chemilumineszenz durch Radikalfänger und ihrer Anregbarkeit durch Sauerstoffradikale wurde der Schluß gezogen, daß nicht die geschwindigkeitsbestimmende, sondern eine nachfolgende Reaktion zwischen einem Phthalhydrazid‐Semichinon und einem 0,H‐Radikal zur Anregung des Phthalhydrazid‐Anions fuhrt. Die Radikale entstehen vermutlich durch Zersetzung eines Peroxyds. Das Licht wird von der Ketoform des Phthalhydrazids emittiert, die bei 400420 mp ein Fluoreszenzmaximum besitzt, wahrend das der Enolform bei 470–480 mp liegt. Die chemische Anregung des Elektronensystems der leuchtenden Substanz wird durch Aufnahme eines Elektrons in einen angeregten Zustand des um ein Elektron ärmeren Substanzradikals gedeutet.
Über das Leitfähigkeitsverhalten verschiedener Phthalocyanine im Vakuum und unter dem Einfluß von Gasen
Authors: Kaufhold Jürgen , Hauffe Karl
Published: March 2014

Das Dunkel‐ und Photoleitfähigkeitsverhalten von metallfreiem Fe‐, Co‐, Ni‐, Cu‐ und Zn‐Phthalocyanin wurde an dünnen Schichten unter dem Einfluß von O2, NO, NO2 und NH3 untersucht. Die Dunkelleitfähigkeit steigt unter O2, NO und NO2 stark an, die zugeordneten “Aktivierungsenergien” erniedrigen sich bis auf 10% des ursprünglichen Vakuumwertes. Die durch die oxydierenden Gase verursachten Leitfähigkeitserhöhungen werden unter NH3 wieder rückgängig gemacht. Ein Photoeffekt ist am Ni‐ und Fe‐Phthalocyanin nicht meßbar; bei den anderen Verbindungen verschwindet er oberhalb eines bestimmten Leitfähigkeitsbereiches. Es wird versucht, den reaktiven Anteil am Verhalten der Verbindungen spektral‐photometrisch zu erfassen. Dabei erwiesen sich Zn‐ und Fe‐Phthalocyanin als relativ instabil. Vergleiche mit den Leitfähigkeitseigenschaften anderer organischer Verbindungen lassen Rückschlüsse auf die Art der Wechselwirkung zwischen Gas und Festkörper zu und geben Hinweise auf den Leitungsmechanismus in organischen Halbleitern.
Polarographische und photoaktivierte Reduktion von Chinonen und Ketonen 3. Mitteilung: Zum Reduktionsmechanismus des Fluoresceins
Authors: Gollmick F. A. , Berg H.
Published: March 2014

Aus den Ergebnissen der polarographischen Reduktion des Fluoresceins im pH‐Bereich von 3–11,6 resultiert ein Mechanismus, der dem von aromatischen Ketonen ähnelt und weitgehend in Übereinstimmung mit den Ergebnissen von Lindquist über Photoreduktionszwischenprodukte steht. In alkalischer Lösung kann das langlebige Radikalanion auf Grund seiner Oxydationsstufe nachgewiesen werden. Seine Reoxydation an der Quecksilbertropfelektrode erfolgt reversibel, was für die bisher postulierten Photoreaktionszyklen von Bedeutung ist.
Der Verlauf der Katalysatorbezugsspannung bei Hydrierungsreaktionen in Lösung
Authors: Beck Fritz
Published: March 2014

Die elektrochemische Bezugsspannung von Hydrierkatalysatoren ist eine charakteristische Größe die mit geringem experimentellem Aufwand erfaßt werden kann. Es werden experimentelle Ergebnisse der simultanen Messung dieser Größe und der Hydriergeschwindigkeit bei der Hydrierung von Substraten mit CC‐Dreifachbindung, bei der Änderung der Rührintensität und bei der Vergiftung des Katalysators mitgeteilt. Diese Ergebnisse lassen sich auf der Grundlage des folgenden, auf der Katalysatoroberfläche ablaufenden Reaktionsschemas deuten:

magnified image

Auf die Möglichkeit der Regelung von Hydrierungsreaktionen mit dieser Methode wird hingewiesen.
Die Absorption von NO‐NO2‐Mischungen durch einen laminaren Wasserstrahl
Authors: Hofmeister Heinz‐Karl , Kohlhaas Rudolf
Published: March 2014

An einem laminaren Strahl wurde die Absorptionsgeschwindigkeit von NO‐NO2‐Mischungen in Wasser in Abhängigkeit vom Oxydationsgrad des Gases gemessen.

Die Absorption wird durch die folgenden zwei chemischen Reaktionen bestimmt:

magnified image

Nach Anwendung einer Regressionsrechnung auf die Ergebnisse und Auswertung nach der Penetrations‐theorie berechnet man für die Geschwindigkeitskonstante (pseudo) erster Ordnung k2 ã 68 sec−1.
Bestimmung des Standardwertes der freien Reaktionsenthalpie für die Bildung von Kohlenoxysulfid aus Kohlenmonoxyd
Authors: Bechtold E.
Published: March 2014

Durch Messung der EMK der Festkörperkette

magnified image

bei 300 °C wurden die Standardwerte der freien Enthalpieänderung der Reaktionen

magnified image

bestimmt.
Dichroismus der Schwingungsbanden des Tetracyanäthylens
Authors: Heim P. , Dörr F.
Published: March 2014

Einkristalle des Tetracyanäthylens, die aus der Schmelze zwischen KBr‐Platten gewonnen wurden, wurden im linear polarisierten Licht vermessen. Aus dem dichroitischen Verhältnis der IR‐Banden, das bei verschiedener Anordnung des Kristalls im Strahlengang gemessen wurde, wird eine Zuordnung der Banden vorgeschlagen und mit den schon bekannt gewordenen Zuordnungen verglichen.
Mass Transfer in Concentrated Binary Electrolytes
Authors: Newman John , Bennion Douglas , Tobias Charles W.
Published: March 2014

The macroscopic description of multicomponent diffusion serves as a basis for the development of equations in a useful form for electrochemical transport problems. A method is proposed for predicting the concentration dependence of the resulting transport parameters.
Reaction rate and separation factor isotope effects in the hydrogen evolution reaction
Authors: Salomon M. , Conway B. E.
Published: March 2014

Calculations are presented for the isotope effects which arise in H2, HD and D2 evolution at Pt and Pd cathodes. It is shown that the quantities SD (separation factor) and R (exchange current density ratio) characterizing the kinetic isotope effects are related in a manner which can be a useful diagnostic indication of reaction mechanism. The method avoids a priori calculation of transition state force constants and hence the associated uncertainties of such calculations.
Eine thermodynamische Theorie zur Lochfraßkorrosion
Authors: Vetter K. J.
Published: March 2014

Es wird ein kurzer Überblick über die Erscheinungen der Lochfraßkorrosion gegeben. Zur Deutung wird angenommen, daß sich im Korrosionsloch eine sehr dünne porenfreie Salzdeckschicht (z.B. Chlorid, Bromid, Jodid) von einer Dicke der Größenordnung 10–100 ° bildet, durch die ein Ionenstrom (Feldstärke 106 bis 10 V/cm) fließt, der äquivalent der Auflösungsgeschwindigkeit der Schicht im ungesättigten Elektrolyten ist und der gleich der hohen Korrosionsstromdichte iK im Loch ist. Das Gleichgewicht der Anionen an der Phasengrenze Salz/Elektrolyt bleibt hierbei ungestört. Eine derartige Salzschicht kann sich nur dann bilden, wenn dies neben der oxidischen Passivschicht thermodynamisch möglich ist.

Auf thermodynamischer Grundlage werden die Bedingungen (Lochfraßpotential ε) diskutiert, bei welchen zwei chemisch verschiedene porenfreie elektronenleitende Metallsalz‐Deckschichten des gleichen Metalls im ungesättigten Elektrolyten nebeneinander auf der gleichen Metalloberfläche im Gleichgewicht sind. Als Grundlage dient hierfür eine Theorie nichtstöchiometrischer Deckschichtelektroden von Vetter. Die Theorie wird auf den Fall erweitert, daß die eine Schicht nicht elektronenleitend (A1, Zr) ist.
Zur Frage des überstöchiometrischen Sauerstoffs im Nickeloxyd Teil II: Weitere experimentelle Ergebnisse und Deutung des Gesamtbefundes
Authors: Gossel Hartmut
Published: March 2014

Zur Ergänzung und Kontrolle früherer Messungen [1] wurden

Das Desorptionsverhalten von polykristallinen Nickeloxydproben, die durch Karbonatzersetzung im Vakuum und anschließende Sauerstoffbehandlung bei 400 bzw. 500°C hergestellt worden waren

Der Einfluß des bei 400°C reversibel adsorbierbaren Sauerstoffs auf die BET‐Oberfläche und

Die Bedeutung der Anwesenheit von Hg‐Dämpfen (pHg ∼ 1·10−3 Torr) während der Sauerstoffbehandlung für den resultierenden Oxydationswert der Proben untersucht.

Hierbei wurde gefunden, a) daß ungefähr 20% des überstöchiometrischen Sauerstoffs nur physikalisch adsorbiert, die restlichen 80% dagegen stärker gebunden sind als einer normalen Chemisorption entspricht, b) der bei 400°C reversibel adsorbierbare Sauerstoff keine merkliche Änderung der BET‐Oberfläche hervorruft, c) Hg‐Dämpfe keine wesentliche Beeinträchtigung des Oxydationswertes unserer Proben bewirken. Ein Deutungsversuch des experimentellen Gesamtbefundes hat zum Ergebnis, daß man zwischen einer Randschichtfehlordnung und einer Volumenfehlordnung unterscheiden muß. Der Fehlordnungsgrad der Randschicht ist höher als der des Kristallinneren. Der Anteil der Randschichtfehlordnung, d.h. des überstochiometrischen Sauerstoffs in der Randschicht, an der Gesamtfehlordnung wird durch das Verhältnis Oberfläche/Volumen der Versuchsprobe und die Herstellungsbedingungen (Sauerstoffbehandlungstemperatur, ‐dauer und ‐druck) bestimmt. Bei nicht zu hochgeglühtem polykristallinem Nickeloxyd (T 1000°C) dominiert dieser Anteil.
Dynamics of Mass Transfer and the Generalized Nonequilibrium Theory of Chromatography
Authors: Giddings J. Calvin
Published: March 2014

The origin and role of nonequilibrium in chromatography is first described, followed by a discussion of the nature of the theoretical problem. The generalized nonequilibrium theory is then developed, leading to an equation for the dispersion of chromatographic zones. It is shown how the generalized nonequilibrium theory can be applied to the special cases of chromatography ‐ particularly adsorption, partition, combined adsorption and partition and diffusion in the mobile phase. The difficulties of comparing theory and experiment are then described, emphasizing those few cases where a quantitative comparison has been possible. A particularly good comparison, obtained with glass bead columns, gives strong support to the theory. It is concluded that such quantitative theory can be applied in two principal ways ‐ to enable the study of physical processes by chromatography and to lead to new chromatographic systems capable of separating substances more efficiently than ever before.
Gas‐Chromatographie als Methode zur Untersuchung der Eigenschaften von Grenzflächen, Adsorptionsschichten und Flüssigkeiten
Authors: Cremer E.
Published: March 2014

Physikalische und chemische Eigenschaften von Grenzflächen, Adsorptionsschichten und Flüssigkeiten sind von entscheidendem Einfluß auf die Verzögerungszeit oder das Verzögerungsvolumen einer Substanz. Die wichtigste thermodynamische Größe, die man aus dem Chromatogramm ermittelt, ist die freie Enthalpie ΔG des Verzögerungsvorganges. Hierbei auftretende Fehler werden diskutiert. Auch Adsorptionsisothermen und absolute Oberflächen lassen sich mit Hilfe gaschromatographischer Methoden bestimmen. Die Kenngrößen L, Hs und I werden definiert, ihre Zusammenhänge mit ΔG aufgezeigt und einige ihrer Vor‐ und Nachteile erörtert.
Probleme der schnellen Gas‐Chromatographie (GC)
Authors: Kaiser R.
Published: March 2014

Die gas‐chromatographische Schnellanalyse ist wichtig für die zu Regelungszwecken eingesetzte Prozeß‐GC, für die Analyse von Vielkomponentengemischen und für Routineanalysen großer Stückzahlen.

Im Vergleich zur normalen GC, die im Mittel 1 Peak je 100 s trennt, ist Ziel der praktischen Schnell‐GC, 1 Peak je 1 s zu trennen. Brauchbarer Bewertungsmaßstab für Schnelltrennungen ist die Größe τ = Trennzahl/Analysenzeit in der Dimension Anzahl Peaks/s.

Es wird gezeigt, daß gepackte Kapillaren mit sogenannter Dünnschichtfüllung nur temperaturprogrammiert ausgesprochene Schnelltrenneigenschaften aufweisen. Sie zeigen ein von der Heizrate abhängiges Maximum der Trennzahl bei sehr hohem Gasdurchgang und sind Säulen und Kapillaren nach der Gasverteilungs‐Chromatographie (LGC) überlegen.

Offene, flüssigkeitsbenetzte Trennkapillaren besitzen bei isothermer Arbeitsweise ein ausgeprägtes Schnelltrennoptimum bei maximalem τ.