bluuebunny/crossref_metadata_2025 huggingface dataset:
Local Production of Sex Hormones and Their Modulation of Hippocampal Synaptic Plasticity
Authors: Ish Hirotaka , Tsurugizawa Tomokazu , Ogiue-Ikeda Mari , Asashima Makoto , Mukai Hideo , Murakami Gen , Hojo Yasushi , Kimoto Tetsuya , Kawato Suguru
Published: July 2007

It is believed that sex hormones are synthesized in the gonads and reach the brain via the blood circulation. In contrast with this view, the authors have demonstrated that sex hormones are also synthesized locally in the hippocampus and that these steroids act rapidly to modulate neuronal synaptic plasticity. The authors demonstrated that estrogens are locally synthesized from cholesterol through dehydroepiandrosterone and testosterone in adult hippocampal neurons. Significant expression of mRNA for P450(17α), P450arom, and other steroidogenic enzymes was demonstrated. Localization of P450(17α) and P450arom was observed in synapses of principal neurons. In contrast to the slow action of gonadal estradiol, hippocampal neuron-derived estradiol may act locally and rapidly within the neurons. For example, 1 to 10 nM estradiol rapidly enhances long-term depression (LTD). The density of thin spines is selectively increased within two hours upon application of estradiol in pyramidal neurons. Estrogen receptor ERα agonist has the same enhancing effect as estradiol on both LTD and spinogenesis. Localization of ERα in spines in addition to nuclei of principal neurons implies that synaptic ERα is responsible for rapid modulation of synaptic plasticity by endogenous estradiol. Activin A, a peptide sex hormone, may also play a role as a local endogenous modulator of synaptic plasticity. NEUROSCIENTIST 13(4):323—334, 2007. DOI: 10.1177/1073858407301396
Community-Based Care Model for High-Risk Adults with Severe Disabilities
Authors: Naylor Mary D. , Hill-Milbourne Veronica R. , Knoble Sefi R. , Robinson Keith M. , Bowles Kathryn H. , Maislin Greg
Published: July 2007

Objective: Evaluate the effectiveness of a home-based intervention for adults with serious physical disabilities at high risk for poor health outcomes.

Design: A pretest/post-test design; content analysis of case studies.

Setting: Five-county Philadelphia metropolitan area.

Patients and Other Participants: Forty-nine community-dwelling adults aged 20—55.

Intervention: Six-month comprehensive care management intervention implemented by Advanced Practice Nurses (APNs) focused on improvement of functional status or prevention of functional decline; management of health problems; and enhancement of self-direction of care by subjects and caregivers.

Main Outcome Measures: Functional status; total hospitalizations, emergency department (ED) and acute care physician visits; symptom management; depression; quality of life; and satisfaction with care.

Results: Between baseline assessment and nine months post-APN intervention, functional status improved (mean = 33.42 → 24.97, p = 0.014). There was a trend toward reductions in average hospitalization rate from 1.10 at baseline to 0.68 nine months post-APN intervention and ED rates from 0.90 to 0.50. Acute care visits to physicians increased from 0.52 to 0.95 from baseline to nine months post-APN intervention. The use of home health aides (mean = 2.72 → 1.37, p = 0.008) and physical therapists (mean = 1.16 → 0.42, p = 0.001) also decreased from baseline to nine months post-APN intervention. Facilitators and barriers to care are identified.

Conclusions: Findings suggest potential benefit of a comprehensive, individualized intervention coordinated by APNs in improving health and functional outcomes and decreasing the use of
Improving Communication at the Transition to Home Health Care: Use of an Electronic Referral System
Authors: Siegler Eugenia L. , Murtaugh Christopher M. , Rosati Robert J. , Schwartz Theresa , Razzano Renee , Sobolewski Sally , Callahan Mark
Published: July 2007

Appropriate and efficient provision of services at home requires more than skilled personnel; effective communication between the primary care provider and the agency is an often overlooked but essential tool for maintaining the patient's health in the community. A method was developed to create home care orders (the “e-485”) that guides the physician through the order writing process, uploads data from the electronic medical record, and creates a legible, complete order set that can be faxed quickly to the agency. This paper describes this tool and the challenges and rewards of its implementation in an academic medical center.
Health Status and Service Needs of Male Inmates Seriously Ill With HIV/AIDS at Two Large Urban Jails
Authors: Karus Daniel , Raveis Victoria H. , Ratcliffe Margaret , Rosefield Herbert A. , Higginson Irene J.
Published: July 2007

Male inmates with HIV/AIDS being served by case-management programs for those seriously ill in jails in Los Angeles ( n = 34) and New Orleans ( n = 20) are described and compared. At both sites, most were Black and poor with a history of substance abuse. Psychological functioning (Mental Health Inventory [MHI-5]) scores indicated poor mental health. Inmates reported an average of more than 10 symptoms, and at least 25% reported needing multiple medical, practical, and social services. These findings document a subpopulation of jail inmates who are seriously ill with HIV/AIDS, and they describe the potential care and service needs of such inmates. Given the chronicity of HIV/AIDS and the importance of strict adherence to treatment protocols, it is important not only to facilitate access to care and services for inmates but also to secure continuity of care and access to services when inmates are transferred to another facility or released into the community.
Ventilation patterns in red kangaroos (Macropus rufusDesmarest): juveniles work harder than adults at thermal extremes, but extract more oxygen per breath at thermoneutrality
Authors: Munn Adam J. , Dawson Terence J. , Maloney Shane K.
Published: July 2007

Juvenile mortalities in large mammals are usually associated with environmental extremes, but the basis for this vulnerability is often unclear. Because of their high surface area to volume ratio, juveniles are expected to suffer greater thermal stresses relative to adults. Coping with thermal stress requires the ventilatory system to accommodate increases in oxygen demand and respiratory water loss at thermal extremes. Because juveniles are smaller than adults, these demands may set up different constraints on their ventilatory system. Using red kangaroos (Macropus rufus Desmarest), an arid zone species, we compared the ventilatory capabilities of juveniles and adults at thermoneutral (25°C) and extreme (–5°C and 45°C) ambient temperatures. We used an allometry to compare juvenile to adult ventilation,using predicted body mass scaling exponents for oxygen consumption (0.75),respiration rate (–0.25), tidal volume (1.0), ventilation rate (0.75)and oxygen extraction (0.0). At ambient 25°C, the juveniles' resting metabolic rate was 1.6 times that of the mature females (ml min–1 kg–0.75), accommodated by significantly higher levels of oxygen extraction of 21.4±1.8%versus 16.6±1.9% (P<0.05). At thermal extremes,juveniles showed typical mammalian responses in their ventilation, mirrored by that of adults, including higher metabolic and ventilation rates at ambient–5°C and shallow panting at 45°C. However, at thermal extremes the juvenile kangaroos needed to work harder than adults to maintain their body temperature, with higher rates of ventilation at ambient –5°C and 45°C, accomplished via larger breaths at –5°C and higher respiratory rates at 45°C.
Modelling of Radiation Damage in Fe-Cr Alloys
Authors: Malerba L. , Terentyev D. A. , Bonny G. , Barashev A. V. , Bjorkas C. , Juslin N. , Nordlund K. , Domain C. , Olsson P. , Sandberg N. , Wallenius J.
Published: July 2007

High-Cr ferritic/martensitic steels are being considered as structural materials for a large number of future nuclear applications, from fusion to accelerator-driven systems and GenIV reactors. Fe-Cr alloys can be used as model materials to investigate some of the mechanisms governing their microstructure evolution under irradiation and its correlation to changes in their macroscopic properties. Focusing on these alloys, we show an example of how the integration of computer simulation and theoretical models can provide keys for the interpretation of a host of relevant experimental observations. In particular we show that proper accounting for two basic features of these alloys, namely, the existence of a fairly strong attractive interaction between self-interstitials and Cr atoms and of a mixing enthalpy that changes sign from negative to positive around 8 to 10 % Cr, is a necessary and, to a certain extent, sufficient condition to rationalize and understand their behavior under irradiation. These features have been revealed by ab initio calculations, are supported by experimental evidence, and have been adequately transferred into advanced empirical interatomic potentials, which have been and are being used for the simulation of damage production, defect behavior, and phase transformation in these alloys. The results of the simulations have been and are being used to parameterize models capable of extending the description of radiation effects to scales beyond the reach of molecular dynamics. The present paper intends to highlight the most important achievements and results of this research activity.
Full-scale Flexural Strength Testing for Stone Cladding Design
Authors: Naggatz Steven G. , Gerns Edward A.
Published: July 2007

Beginning with the Industrial Revolution and rapidly increasing following World War II, building cladding systems changed dramatically. Exterior wall construction that had previously consisted of thick mass masonry evolved into contemporary curtain wall systems. As curtain wall systems evolved, the economics of reducing the thickness of curtain wall components became more important. The use of thin stone veneers on buildings in the modern era was not associated with increased knowledge of stone material properties based on testing and research. Rather, the reduction in thickness is attributable to advancements in fabrication technology, economy in construction, and a rational approach to design of veneer systems. This paper will discuss the evolution of the use of stone in curtain wall systems and the associated ASTM standards for building stone. Early ASTM standards for building stone were limited to tests used to evaluate the compression strength of stone which was consistent for mass bearing walls of the early 20th century. As stone was increasingly used more as a veneer, standards for modulus of rupture (ASTM C 99) were introduced. As systems continued to evolve, flexural strength (ASTM C 880) was introduced to address material variability. The evolution of ASTM C 880 included increasing specimen width to further incorporate variability of the stone. Recently, the authors have introduced full panel testing in the design and evaluation process. This paper will present data and discuss the differences in test results for three case studies where both ASTM C 880 specimens and full panel flexural strength testing was performed. The focus of this section will be to discuss the implications of performing full-size panel testing in addition to ASTM C 880 standard specimen testing on design of stone cladding systems for tall building construction as a natural evolution of the design and evaluation process for thin stone cladding systems.
Characteristics That Affect the Integrity of Existing Thin Stone Cladding
Authors: Lewis Michael D.
Published: July 2007

Prestigious structures began using thin natural stone panels as wall cladding to give them historic character in the late 1960s. Easier fabrication methods increased stone production and enabled larger, thinner panels that were lightweight. Unfortunately, engineering and testing did not keep pace. Inadequate initial evaluation of material durability and panel strength resulted in varying degrees of distress developing in some claddings. Because early stone cladding was installed with little structural analysis, current evaluation should predict capability by checking characteristics initial engineering likely ignored. Comprehending all characteristics that affect the integrity of thin stone cladding must be the objective of a responsible maintenance program. The program must evolve with each evaluation’s findings to adapt to the specifics of that building and its changes over time. Maintaining the safety of a building’s skin is essential to extending the service life of the whole structure. Verifying safety requires more than a cursory visual check for exposed elements to find them before they fall. In the past, stone cladding was completely removed from too many structures that experienced distress. Some evaluations misunderstood or misdiagnosed affect of distress on integrity. They failed to investigate some characteristics, or did not relate others, yielding an incomplete assessment. Adding evaluation of characteristics common to traditional structural assessment to a cladding program adds rigor and objectivity, avoiding misdiagnosis and unjustified expense. In rare cases, remove-and-replace-all may still be required, but only if gross problems exist with support. However, in most cases, an appropriate program will not only identify the parts creating the highest risk, but the program can prescribe selective replacement instead of complete recladding as a long-term remedy.
Cloning
Authors: Murdoch Alison
Published: July 2007

Key content

Reproductive cloning is prohibited in the United Kingdom and there is legislation banning it in some other countries.

The therapeutic potential of being able to grow unlimited supplies of functioning, differentiated cells of different types is immense.

One possible application in gynaecology might be to use cell‐based therapies to replace the endometrium and to treat myometrial scars and bladder wall or vaginal deficiencies.

A licence to undertake somatic cell nuclear transfer for the derivation of stem cells was granted in the UK in 2004 and the first blastocyst described in 2005.

One potential way of obtaining oocytes might be to ask women undergoing in vitro fertilisation to donate some of theirs.

Learning objectives

To learn about the moral and ethical issues surrounding human cloning.

To be aware of the potential use of cloning in gynaecology.

To be informed about the current research.

Ethical issues

How can oocytes be obtained without risk to the donor?

Is it ethical to pay women to donate oocytes?

Please cite this article as: Murdoch A. Cloning. The Obstetrician & Gynaecologist 2007;9:177–180.
Puerperal genital haematoma: a commonly missed diagnosis
Authors: Mawhinney Sandra , Holman Ruth
Published: July 2007

Key content

Although uncommon, puerperal genital haematomas can be associated with serious maternal morbidity.

An abnormally high level of perineal pain following childbirth is a hallmark symptom.

The primary aims of treatment are to prevent further blood loss and correct hypovolaemia.

There is debate regarding the optimal management of genital haematoma.

Learning objectives

To understand the aetiology of puerperal genital haematoma.

To recognise the signs and symptoms and know how they are classified according to their location.

To learn about the most appropriate methods of treatment.

Ethical issues

How should we choose the most appropriate treatment when research on the condition is scarce?

Should resources be used to ensure interventional radiology services are available to all maternity units?

Please cite this article as: Mawhinney S, Holman R. Puerperal genital haematoma: a commonly missed diagnosis. The Obstetrician & Gynaecologist 2007;9:195–200.
The Interaction of the Wnt and Notch Pathways Modulates Natural Killer Versus T Cell Differentiation
Authors: Aoyama Keisuke , Delaney Colleen , Varnum-Finney Barbara , Kohn Aimee D. , Moon Randall T. , Bernstein Irwin D.
Published: July 2007

The Wnt and Notch signaling pathways have been independently shown to play a critical role in regulating hematopoietic cell fate decisions. We previously reported that induction of Notch signaling in human CD34+CD38− cord blood cells by culture with the Notch ligand Delta1 resulted in more cells with T or natural killer (NK) lymphoid precursor phenotype. Here, we show that addition of Wnt3a to Delta1 further increased the percentage of CD34−CD7+ and CD34−CD7+cyCD3+ cells with increased expression of CD3ε and preTα. In contrast, culture with Wnt3a alone did not increase generation of CD34−CD7+ precursors or expression of CD3ε or preTα gene. Furthermore, Wnt3a increased the amount of activated Notch1, suggesting that Wnt modulates Notch signaling by affecting Notch protein levels. In contrast, addition of a Wnt signaling inhibitor to Delta1 increased the percentage of CD56+ NK cells. Overall, these results demonstrate that regulation of Notch signaling by the Wnt pathway plays a critical role in differentiation of precursors along the early T or NK differentiation pathways.

Disclosure of potential conflicts of interest is found at the end of this article.
Nitric Oxide Donor Upregulation of Stromal Cell-Derived Factor-1/Chemokine (CXC Motif) Receptor 4 Enhances Bone Marrow Stromal Cell Migration into Ischemic Brain After Stroke
Authors: Cui Xu , Chen Jieli , Zacharek Alex , Li Yi , Roberts Cynthia , Kapke Alissa , Savant-Bhonsale Smita , Chopp Michael
Published: July 2007

Stromal cell-derived factor-1 (SDF1) and its chemokine (CXC motif) receptor 4 (CXCR4), along with matrix metalloproteinases (MMPs), regulate bone marrow stromal cell (BMSC) migration. We tested the hypothesis that a nitric oxide donor, DETA-NONOate, increases endogenous ischemic brain SDF1 and BMSC CXCR4 and MMP9 expression, which promotes BMSC migration into ischemic brain and thereby enhances functional outcome after stroke. C57BL/6J mice were subjected to middle cerebral artery occlusion (MCAo), and 24 hours later, the following were intravenously administered (n = 9 mice per group): (a) phosphate-buffered saline; (b) BMSCs (5 × 105); (c) 0.4 mg/kg DETA-NONOate; (d) combination of CXCR4-inhibition BMSCs with DETA-NONOate; and (e) combination of BMSCs with DETA-NONOate. To elucidate the mechanisms underlying combination-enhanced BMSC migration, transwell cocultures of BMSC with mouse brain endothelial cells (MBECs) or astrocytes were performed. Combination treatment significantly improved functional outcome after stroke compared with BMSC monotherapy and MCAo control, and it increased SDF1 expression in the ischemic brain compared with DETA-NONOate monotherapy and MCAo control. The number of BMSCs in the ischemic brain was significantly increased after combination BMSC with DETA-NONOate treatment compared with monotherapy with BMSCs. The number of engrafted BMSCs was significantly correlated with functional outcome after stroke. DETA-NONOate significantly increased BMSC CXCR4 and MMP9 expression and promoted BMSC adhesion and migration to MBECs and astrocytes compared with nontreatment BMSCs. Inhibition of CXCR4 or MMPs in BMSCs significantly decreased DETA-NONOate-induced BMSC adhesion and migration. Our data demonstrate that DETA-NONOate enhanced the therapeutic potency of BMSCs, possibly via upregulation of SDF1/CXCR4 and MMP pathways, and increased BMSC engraftment into the ischemic brain.

Disclosure of potential conflicts of interest is found at the end of this article.
The Development of a Generic Bioanalytical Matrix Using Polydiacetylenes
Authors: Lee S. W. , Kang C. D. , Yang D. H. , Lee J.‐S. , Kim J. M. , Ahn D. J. , Sim S. J.
Published: July 2007

In order to develop more user‐viable formats for polydiacetylene (PDA) biosensors, it is necessary to control the biochemical and physical properties of the PDA matrix. In this study, we prepare polydiacetylene liposomes from controlled mixtures of 10,12‐pentacosadiynoic acid (PCDA) and PCDA–MI, a PCDA derivative with a maleimide headgroup. Both the chemical and physical properties of the liposome are easily manipulated by controlling the molar ratio of PCDA to PCDA–MI during liposome preparation. After preparing the liposomes, the activity of the maleimide headgroups increases linearly with the PCDA–MI content for concentrations in the range of 0–30 %. As a result, the antibody‐binding characteristics of the PDA liposomes increase with PCDA–MI content. It is also possible to modulate the physical properties of the liposome. Differential scanning calorimetry measurements show that the phase organization of the liposome is progressively lost with increasing PCDA–MI content. Furthermore, the liposomes show an increased color change in response to temperature that is also dependent on PCDA–MI content, indicating increased membrane fluidity. When PCDA:PCDA–MI liposomes are conjugated with a cell‐specific antibody the response to the antigen induces a color change that is dependent on the PCDA–MI content. Consequently, it is deduced that the increased sensitivity of the liposomes containing higher PCDA‐MI content is due to increased antibody binding and membrane fluidity. From these experiments, we identify the factors controlling the colorimetric properties of the PDA matrix and demonstrate that it is possible to modulate the sensitivity and stability of PDA biosensors by controlling the ratio of constituent monomers.
Optical sensor for aliphatic amines based on the simultaneous colorimetric and fluorescence responses of smart textile
Authors: Staneva Desislava , Betcheva Rositza , Chovelon Jean‐Marc
Published: July 2007

The pH indicator proposed is a water‐soluble dye based on benzo[de]antracen‐7‐one. Dissolving in buffered aqueous solution, it changes color from yellow to orange and in the mean time decreases its fluorescence emission as a function of the amine concentration. Viscose fabric, dyed with the same dye has been investigated as a new reversible colorimetric and fluorescent sensor material for ammonia and aliphatic amines in buffered solution. The high value of the dye pKa and the influence of the textile matrix on the selective detection of dimethylamine compared to ammonia, trimethylamine, and metylamine have been studied. The different response of the solution and textile matrix as well as the optical analyses both as a color change and a fluorescence emission have been discussed. The advantage of this sensor is the fact that depending on the analytical problem to be solved and the available instrumentation it can be used either as a fluorogenic or as a chromogenic chemosensor. In addition, the textile sensor is characterized by facile fabrication, low cost, sensibility, and reproducibility. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Arsenite retention properties of water‐soluble metal–polymers
Authors: Rivas Bernabé L. , Aguirre María del Carmen
Published: July 2007

The properties of water‐soluble metal–polymers to retain As(III) from aqueous solution are investigated. Poly(acrylic acid)s with different tin contents are prepared. Amounts of 3, 5, 10, and 20 wt % of tin are added to the polymer. The metal compositions are evaluated by thermogravimetry (TG‐DSC) and atomic absorption spectroscopy. Structural properties are analyzed by infrared and 1H nuclear magnetic resonance spectroscopy, and X‐ray diffraction. Additionally, specific surface area was measured using CO2 as adsorbate. Arsenic retention properties are studied using the liquid‐phase polymer‐based retention (LPR) technique. The polymers can bind arsenic species from an aqueous solution in the pH range 4–8. The studies show that the retention capacity is a function of tin content and polymer concentration. At pH 8, the following mol ratios poly(AA)‐Sn : As(III) are analyzed: 600 : 1, 400 : 1, 200 : 1, 100 : 1, and 20 : 1. The highest retention, 80%, is obtained with poly(AA)‐Sn at 10 and 20 wt % of tin at mole ratios 400 : 1, and at nearly to 20 : 1 or 40 : 1 Sn‐As(III). The highest retention is observed at pH 8 and 4. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Synthesis of novel amino(alkylamino)deoxychitosans and those thiol‐derivatives and the chemisorption behaviors of an acid dye and Hg2+ ion onto the resulting polymers
Authors: Shimizu Yoshiaki , Akiyama Kenji , Saito Yoshihiro , Nakamura Takeo
Published: July 2007

Introducing an additional functionality to chitosan, novel chitosan‐based materials were synthesized. The reactions of tosylchitosan with ammonia, ethylenediamine, and hexamethylenediamine have been studied, and the chemisorption behavior of a typical acid dye (CI Acid Orange 7) onto the resulting polymers has been evaluated. Thiol groups were introduced to the above chitosan derivatives having additional amino group at the C6 position, and the chemisorption behavior of Hg2+ ion onto the resulting polymers was measured and compared with that of N‐thioacetylchitosan. The successful synthetic reaction was demonstrated by the infrared spectroscopic measurements. It has been confirmed that the abilities of the chitosan derivatives with additional amino groups to the chemisorption of an acid dye were significantly high, and that the saturation value of the chemisorption amount of CI Acid Orange 7 toward one of 2′‐aminoethylaminodeoxychitosans was significantly high as 6.16 mol/kg. The results also showed that the saturation amounts of Hg2+ ion chemisorption were larger with the increase in the thiol group content of the chitosan derivatives with the thiol groups. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Kinetics of isothermal crystallization and subsequent melting behavior of PTT/PA12 blend
Authors: Asadinezhad A. , Jafari S. H. , Khonakdar H. A. , Böhme F. , Hässler R. , Häussler L.
Published: July 2007

The kinetics of isothermal crystallization along with subsequent melting behavior of melt‐mixed immiscible binary blends of poly(trimethylene terephthalate) (PTT) and polyamide‐12 (PA12) were investigated by means of differential scanning calorimetry. Three macrokinetic models of Avrami, Tobin, and Malkin were used which could adequately describe isothermal crystallization kinetics of the blends as well as the neat components. However, the commonly used Avrami model provided more consistent data for the system of interest. Based on the half‐time of crystallization, one could conclude that PTT crystallizes more rapidly than PA12. The kinetic parameters suggested that blending had a distinct influence on reducing the rate of isothermal crystallization particularly at medium degrees of undercooling. From reciprocal crystallization half‐time, it was concluded that over the temperature range covered; the samples crystallized inside the nucleation‐controlled region. The secondary nucleation mechanism generally prevailed in the PA12 isothermal crystallization whereas in PTT, the primary crystallization mechanism dominated. With respect to the position of melt transitions, blending was proven to exert only small effects, however, it reduced the crystallinity of both constituents particularly that of PA12 significantly. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Effect of morphology on the electric conductivity of binary polymer blends filled with carbon black
Authors: Xu Zhongbin , Zhao Chao , Gu Aijuan , Fang Zhengping , Tong Lifang
Published: July 2007

Several carbon black (CB)‐filled binary polymer blends were prepared in Haake rheometer. Distribution states of CB and effect of morphology on the electric conductivity of different ternary composites were investigated. Under our experimental condition CB particles located preferentially at the interface between polymethyl methacrylate (PMMA) and polypropylene (PP) in PMMA/PP/CB composites, in high‐density polyethylene (HDPE) phase in PP/HDPE/CB composites, and in Nylon6 (PA6) phase in polystyrene (PS)/PA6/CB, PP/PA6/CB, PMMA/PA6/CB, and polyacrylonitrile (PAN)/PA6/CB composites; the ternary composites in which CB particles locate at the interface of two polymer components have the highest electric conductivity when the mass ratio of the two polymers is near to 1 : 1. The ternary composites in which CB particles located preferentially in one polymer have the highest electric conductivity usually when the amount of the polymer component having CB particles is comparatively less than the amount of the polymer component not having CB particles; if the formulations of PS/PA6/CB, PP/PA6/CB, and PMMA/PA6/CB composites equaled and PA6/CB in them is in dispersed phase, PS/PA6/CB composites have the highest electric conductivity and PP/PA6/CB composites have the lowest electric conductivity; suitable amount of PS or PAN in PA6/CB composites increase the electric conductivity due in the formation of a parallel electrocircuit for electrons to transmit. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007
Decomposition of a Lignin Model Compound under Hydrothermal Conditions
Authors: Wahyudiono  , Kanetake T. , Sasaki M. , Goto M.
Published: July 2007

Lignin, which is the second most abundant polymeric aromatic organic substance in wood biomass after cellulose, and contains many oxygen‐based functional groups, has been proposed as an alternative source of chemical compounds. Guaiacol, a model compound for lignin, was reacted in supercritical water using a batch‐type reactor at temperatures of 653–673 K and various pressures under an argon atmosphere. The effects of temperature and reaction time at the same pressure were combined into a single severity parameter that was used to monitor the decomposition of guaiacol to its derived compounds. The main products in aqueous solution were catechol, phenol, and o‐cresol. The amounts present approached 40.73 wt %, 14.18 wt %, and 4.45 wt %, respectively. With an increase in the reaction time at the same conditions, the amount of guaiacol decreased and the quantity of derived compounds of guaiacol increased. Based on the experimental results, a reaction mechanism for the decomposition of guaiacol was proposed. The process investigated in this study may form the basis for an efficient method of wood biomass decomposition.
Application of Interference Microscopy and IR Microscopy for Characterizing and Investigating Mass Transport in Nanoporous Materials
Authors: Heinke L. , Chmelik C. , Kortunov P. , Ruthven D. M. , Shah D. B. , Vasenkov S. , Kärger J.
Published: July 2007

The application of interference microscopy has provided an important breakthrough in the study of the transport of guest molecules in nanoporous materials, making it possible to observe the transient intracrystalline concentration profiles resulting from a well‐defined change (usually a step) in the ambient gas pressure. This approach was used to study adsorption and desorption kinetics in several zeolite systems. The advantages of this technique, especially when combined with infrared absorption measurements, are illustrated by experimental results obtained in a study of the methanol‐ferrierite system.
Study of Ethylene Polymerization Under Single Liquid Phase and Vapor‐Liquid Phase Conditions in a Continuous‐Flow Tubular Reactor
Authors: Beigzadeh D. , Nielsen C. A.
Published: July 2007

The feasibility of using continuous‐flow tubular reactors (CFTR) as an efficient research tool for polymerization reactions is investigated. This is a continuation of the extensive effort that had been made at Dow in recent years to set up and employ an electro‐thermal microreactor (an ohmically‐heated CFTR), which resulted in several internal and external publications and a US Patent. The main focus of this work is to investigate the effect of operating conditions and flow composition, mainly the number of existing phases, on the molecular weight of the polymer. A series of polymerization experiments were performed in single‐phase (liquid) and two‐phase (vapor‐liquid) flow regimes. In single‐phase polymerization, the ethylene concentration falls continuously along the length of the reactor. This will have a significant effect on the kinetics of polymerization, particularly the molecular weight of the produced polymer. A key advantage of operating in the two‐phase region is that an almost constant ethylene concentration is maintained along the length of the reactor. In effect, the vapor phase serves as a reservoir that replenishes the ethylene consumed in the liquid phase by polymerization. The molecular weight data show that this assumption is valid provided that the rate of mass transfer is significantly higher than the rate of the polymerization reaction.
Enhancement of Methanol Production in a Membrane Dual‐Type Reactor
Authors: Rahimpour M. R. , Lotfinejad M.
Published: July 2007

In this study, a dynamic model for a membrane dual‐type methanol reactor was developed in the presence of long term catalyst deactivation. The proposed model is used to compare the performance of a membrane dual‐type methanol reactor with a conventional dual‐type methanol reactor. A conventional dual‐type methanol reactor is a shell and tube heat exchanger reactor in which the first reactor is cooled with cooling water and the second one is cooled with synthesis gas. In a membrane dual‐type reactor, the wall of the tubes in the gas‐cooled conventional reactor is covered with a palladium‐silver membrane, which is only permeable to hydrogen. Hydrogen can penetrate from the feed synthesis gas side into the reaction side due to the hydrogen partial pressure driving force. Hydrogen permeation through the membrane shifts the reaction towards the product side according to the thermodynamic equilibrium. The proposed dynamic model was validated against measured daily process data of a methanol plant recorded for a period of four years and a good agreement was achieved. The simulation results show that there is a favorable profile of temperature and activity of the membrane dual‐type reactor relative to single and conventional dual‐type reactor systems. Therefore, the performance of methanol reactor systems improves when a membrane is used in a conventional dual‐type methanol reactor.
In3Ti2Br9: Jahn‐Teller Unstable Indium(I) and Antiferromagnetically Coupled Titanium(III) Atoms
Authors: Dronskowski Richard
Published: July 2007

Dark green crystals of In3Ti2Br9 have been synthesized from elemental Ti and molten InBr3 at 450°C. The X‐ray diffractional characterization by means of single‐crystal and powder Rietveld refinement reveals a hexagonal crystal structure (a = 738.2(2), c = 1813.9(3) pm; P63/mmc, Z = 2) of Cs3Cr2Cl9 type, containing Ti2Br3−9 dimers and univalent indium cations. Self‐consistent, semiempirical band structure calculations show the structural distortions of the two monovalent indium cations to arise from a second‐order Jahn‐Teller instability. The new compound's magnetic susceptibility and microscopic antiferromagnetic exchange are analyzed by using a Bleaney‐Bowers ansatz.
Novel Metastable Structures of WO3, MoO3 and W1‐xMoxO3 Obtained by the Deintercalation of Layered Amine Adducts
Authors: Ayyappan S. , Subbanna G. N. , Rao C. N. R.
Published: July 2007

Deintercalation of amines from the layered amine adducts of WO3, MoO3 and W1‐xMoxO3 has been employed as a soft chemical route to produce unusual metastable structures of the oxides. After the adducts of WO3, MoO3 and W1–xMoxO3 (x = 0.25, 0.5, 0.75) with amines such as triethylamine (TEA), pyridine, n‐butylamine and n‐octylamine had been characterized, deintercalation was carried out thermally as well as by acid leaching. Thermal deintercalation yielded novel metastable structures of WO3 and MoO3 that were significantly different from the stable forms, which contain distorted metal‐oxygen octahedra. Thus, ReO3‐type cubic WO3 was obtained by the thermal deintercalation of WO3 · 0.5 TEA. Acid leaching of the amines gave metastable phases of WO3, MoO3 and W1‐xMoxO3, which were different from those obtained thermally. All the metastable phases transformed to the corresponding stable forms at higher temperatures.
The Reaction of H2S with SO2: Molecular Structures, Energies, and Vibrational Data of Seven Isomeric Forms of H2S3O
Authors: Drozdova Yana , Steudel Ralf
Published: July 2007

High‐level ab initio MO calculations (MP2/6‐311G**//MP2/6‐311G**) on 16 isomeric forms of H2S3O (including rotamers) have been performed. The nonhelical hydroxotrisulfane HOSSSH 1a (motif + + −) is the most stable isomer, while the chains with motifs + + + and + − + are less stable by 1.7 and 3.7 kJ mol−1, respectively. The other isomers of H2S3O increase in energy in the order HSS(O)SH < HOS(S)SH < HSOSSH < HS(O)SSH < HS(S)SOH < HS(S)OSH. The trisulfane‐2‐oxide HSS(O)SH 2a (symmetry C1) is less stable than 1 a by 67 kJ mol−1. These molecules may be formed from H2S and SO2 via H2S2O2 by condensation with H2S. The calculated reaction energies support the view that H2S3O is a key intermediate in the room‐temperature reaction of H2S and SO2 resulting in the formation of lower oxoacids of sulfur and finally in sulfane oxides.
Correlations Between Structure, Magnetism, and Polymerization Activity of Paramagnetic Benzylchromium Complexes
Authors: Bhandari Gautam , Rheingold Arnold L. , Theopold Klaus H.
Published: July 2007

Reaction of [{Cp*Cr(μ‐Cl)}2] with benzyllithium yielded [{Cp*Cr‐(μ‐Bz)}2] (1), a CrII alkyl complex with bridging benzyl groups and a CrCr bond, which rearranged at room temperature to [Cp*Cr(η1‐Bz)(μ‐η3:η6‐Bz)CrCp*] (2), a mixed valent (CrI/CrIII) complex with a benzyl ligand coordinating as an η6‐arene ligand to one chromium and as an η3‐allyl ligand to the other one. Upon heating, 2 reductively eliminated bibenzyl and yielded [(Cp*Cr)2(μ‐η6:η6‐Bz‐Bz)] (3), in which two 17‐electron sandwich complexes are linked by an ethano bridge. The crystal structures of 2 and 3 have been determined. Magnetic susceptibility and saturation magnetization measurements showed 2 to be ferromagnetically coupled (ground state S = 2, J = + 23(1) cm−1). Of the three isomers, only 2 catalyzed the polymerization of ethylene, presumably because it contains a CrIII alkyl.
Asymmetric syn‐Selective Michael Addition of Enolates to Chiral 8‐Phenylmenthyloxy Vinyl Chromium Carbene Complexes
Authors: Barluenga José , Montserrat Javier M. , Flórez Josefa , Garcia‐Granda Santiago , Martin Eduardo
Published: July 2007

Michael addition reactions of ketone and ester lithium enolates to optically active Fischer vinylcarbene complexes derived from (‐)‐8‐phenylmenthol take place with high syn selectivity and high levels of asymmetric induction. The initial Michael adducts can be further elaborated through diastereoselective addition of organometallic reagents to ketones and aldol reactions. Removal of the metal fragment and chiral auxiliary group leads to cyclic enol ethers with three or five contiguous stereogenic centers and of high enantiomeric purity.
Diastereo‐ and Enantioselective Synthesis of L‐threo‐ and D‐erythro‐Sphingosine
Authors: Enders Dieter , Whitehouse Darren L. , Runsink Jan
Published: July 2007

L‐threo‐sphingosine and its D‐erythro isomer (1) are subunits of many glycosphingolipids, gangliosides and ceramides. This paper describes the highly diastereo‐ and enantioselective synthesis of both isomers (de, ee > 98%). The key steps in the synthesis are the aldol reaction of the SAMP hydrazone (S)‐2 with racemic α‐phenylselenylpentadecanal 3, the diastereoselective triacetoxyborohydride reduction of ketone 5 and exclusive (E) CC double bond formation in the elimination of hydroxyl and selenyl moieties promoted by methanesulfonyl chloride. Mesylate 8 was then readily converted via the 1,3‐O‐acetonide‐protected azidosphingosine 9 to L‐threo‐sphingosine. Conversion to the known 1‐O,2‐N‐diacetyl‐protected sphingosine 13 with subsequent Mitsunobu inversion of the C3OH centre afforded the D‐erythro‐sphingosine epimer.
Phase Relationships in the N2O3/N2O4 System and Crystal Structures of N2O3
Authors: Horakh Jörg , Borrmann Horst , Simon Arndt
Published: July 2007

Mixtures of N2O3 and N2O4 have been prepared from measured volumes of NO and O2. Phase relationships in the system N2O3/N2O4, which depend on the composition of the samples and on the temperature, were studied by the Guinier technique and differential thermal analysis. Single crystals of phases A and B of N2O3 were grown in situ on a diffractometer and studied at temperatures between −107 and −170°C by X‐ray diffraction. The structure analysis of A‐N2O3 (tetragonal, space group I41/a, T = −170°C, a = 1625.57 (16), c = 880.49(13) pm, Z = 32, R1 = 0.051 for 1030 unique reflections) is hampered by twinning and additional disorder of one of two crystallographically independent molecules. B‐N2O3 is nicely ordered with one molecule in the asymmetric unit (orthorhombic, space group P212121, T = −160°C, a = 506.86(4), b = 647.96(5), c = 863.26(6) pm, Z = 4, R1 = 0.023 for 1352 unique reflections). The most interesting features of the N2O3 molecule are its planarity and the extraordinarily long NN bond (189.0(1) pm).
Biologically Induced Reduction in Symmetry: A Study of Crystal Texture of Calcitic Sponge Spicules
Authors: Aizenberg Joanna , Hanson Jonathan , Koetzle Thomas F. , Leiserowitz Leslie , Weiner Stephen , Addadi Lia
Published: July 2007

Organisms can exert a remarkable degree of control over crystal growth. One way of achieving this is by the adsorption of specialized macromolecules on specific planes of the growing crystals. With continued growth of the crystal, the macromolecules are incorporated inside the crystal bulk. Their presence does not change the crystal structure, but creates discontinuities in the perfect lattice. Here we study in detail three unusual cases of reduction in symmetry at the level of crystal domain shapes, induced by this controlled intercalation. We examined sponge spicules, which are single crystals of Mg‐bearing calcite. They were specifically chosen for this study, because their morphologies do not reflect the hexagonal symmetry of calcite. Their crystal textures (coherence lengths and angular spreads) were characterized by high‐resolution X‐ray diffraction with well‐collimated synchrotron radiation. The results are compared to analogous studies of synthetic calcite and Mg‐bearing calcite. In all the selected spicules reduction in symmetry is observed in the coherence lengths among symmetry‐related crystallographic directions. The reconstructed shapes of the domains of perfect structure closely match the specific spicule morphologies. The synthetic crystals show no such reduction in symmetry. Although the manner by which such exquisite control is achieved is not known, we envisage it involving a combination of oriented nucleation with either physical or stereochemically driven adsorption.
Weak Interactions in Crystals: 4,4′‐Di(tert‐butyl)‐N‐N′‐bipyridinium Diperchlorate—A Biphenyl Analogue with Perpendicular Pyridine Rings
Authors: Bock Hans , Nick Sabine , Näther Christian , Bensch Wolfgang
Published: July 2007

Oxidation of substituted N‐aminopyridinium compounds yields bipyridinium salts. After anion exchange Br− → CIO, it was possible to grow single crystals from the 4,4′‐di(tert‐butyl) derivative. The structure determined at 100 K shows a dihedral angle of 84° between the molecular halves connected by a shortened NN bond of 143 pm in length. This result is contrary to that expected from the isoelectronic correspondence 〉CC〈↔〉NN〈, which would suggest planarity, as has been observed experimentally both in solid biphenyl, and in tetraalkylhydrazine dications and radical cations. Lattice packing analysis, however, reveals the presence of hydrogen bonds C(H)…O between the phenyl rings and the perchlorate anions. AM 1 enthalpy hypersurface calculations for the isoelectronic series H5C5X–YC5H5 (X–Y = CC, +NC, +NN+, −BN+, BC, and BB−) predict single‐minimum potentials for both the dication 〉NN〈 as well as the dianion 〉BB〈 with the molecular halves twisted perpendicular to each other. In detailed model calculations, counteracting effects of π electron density delocalization vs. H/H repulsion of the ortho ring hydrogens adjacent to the central bond seem to dictate the delicate balance of the biphenyl twisting. For further experimental confirmation, the structure of the isosteric molecule 4,4′‐di(tert‐butyl)biphenyl has been determined: in contrast to the unsubstituted π hydrocarbon with a latticeenforced dihedral angle of 0°, close to the calculated value, the two molecular halves are twisted by 40°—as in biphenyl in the gas phase.
Transfer Hydrogenation of Nitro‐, Nitroso‐ and Azoarenes by Homolytic Retrodisproportionation
Authors: Coellen Michael , Rüchardt Christoph
Published: July 2007

Nitro‐, nitroso‐ and azobenzene are reduced almost quantitatively to aniline when heated to 230–300°C with 9,10‐dihydroanthracene (DHA), xanthene or tetralin. From the effect of polar substituents and polar solvents on the reactivity and from the isotope effect kH/kD ≈︁ 2.4 (280°C), a hydrogen‐atom transfer from the H donor to the acceptor (retrodisproportionation) is proposed as the rate‐determining step. The lower reactivity of xanthene compared with 9,10‐dihydroanthracene eliminates the possibility of a rate‐determining hydride transfer. The observation of an intense ESR signal of 9‐xanthyl radicals during the reaction in diphenyl ether and the typical products support the proposed homolytic mechanism.
Bimolecular Gas‐Phase Reactions of d‐Block Transition‐Metal Cations With Dimethyl Peroxide: Trends Across the Periodic Table
Authors: Wesendrup Ralf , Schalley Christoph A. , Schröder Detlef , Schwarz Helmut
Published: July 2007

The bimolecular gas‐phase reactions of d‐block transition‐metal cations M+ with dimethyl peroxide were screened by means of Fourier transform ion cyclotron resonance mass spectrometry. The rich chemistry can be classified into four types of reactions: i) Oxygen‐atom transfer to generate MO+, ii) elimination of radicals, mostly CH3O˙, iii) intramolecular redox reaction of dimethyl peroxide to form CH3OH, CH2O and CO, and iv) charge transfer from the metal cation to produce CH3OOCH3+. Some general trends became apparent from this study. For example, the “early” transition metals almost exclusively induce oxygen transfer to generate MO+, in line with the notoriously high oxophilicities of these metals, and electron transfer is only observed for Zn+ and Hg+. Both the radical loss and the disproportionation reaction emerge from a rovibrationally highly excited insertion intermediate (CH3O)2M+, and for the first‐row metals the branching ratio of the competing processes seems to be affected by the M+OR bond strengths as well as the electronic groundstate configurations of M+. For the 4d and 5d cations Ru+Ag+ and Pt+Au+, respectively, products resulting from intramolecular redox reactions dominate; this probably reflects the higher propensity of these metal ions to facilitate β‐hydrogen atom shifts.