bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel biological function for CD44 in axon growth of retinal ganglion cells identified by a bioinformatics approach
Authors: Ries Albert , Goldberg Jeffrey L. , Grimpe Barbara
Published: September 2007

The failure of CNS regeneration and subsequent motor and sensory loss remain major unsolved questions despite massive accumulation of experimental observations and results. The sheer volume of data and the variety of resources from which these data are generated make it difficult to integrate prior work to build new hypotheses. To address these challenges we developed a prototypic suite of computer programs to extract protein names from relevant publications and databases and associated each of them with several general categories of biological functions in nerve regeneration. To illustrate the usefulness of our data mining approach, we utilized the program output to generate a hypothesis for a biological function of CD44 interaction with osteopontin (OPN) and laminin in axon outgrowth of CNS neurons. We identified CD44 expression in retinal ganglion cells and when these neurons were plated on poly‐l‐lysine 3% of them initiated axon growth, on OPN 15%, on laminin‐111 (1×) 41%, on laminin‐111 (0.5×) 56%, and on a mixture of OPN and laminin (1×) 67% of neurons generated axon growth. With the aid of a deoxyribozyme (DNA enzyme) to CD44 that digests the target mRNA, we demonstrated that a reduction of CD44 expression led to reduced axon initiation of retinal ganglion cells on all substrates. We suggest that such an integrative, applied systems biology approach to CNS trauma will be critical to understand and ultimately overcome the failure of CNS regeneration.
Chronic treatment with glucocorticoids alters rat hippocampal and prefrontal cortical morphology in parallel with endogenous agmatine and arginine decarboxylase levels
Authors: Zhu Meng‐Yang , Wang Wei‐Ping , Huang Jingjing , Regunathan Soundar
Published: September 2007

In the present study, we examined the possible effect of chronic treatment with glucocorticoids on the morphology of the rat brain and levels of endogenous agmatine and arginine decarboxylase (ADC) protein, the enzyme essential for agmatine synthesis. Seven‐day treatment with dexamethasone, at a dose (10 and 50 μg/kg/day) associated to stress effects contributed by glucocorticoids, did not result in obvious morphologic changes in the medial prefrontal cortex and hippocampus, as measured by immunocytochemical staining with β‐tubulin III. However, 21‐day treatment (50 μg/kg/day) produced noticeable structural changes such as the diminution and disarrangement of dendrites and neurons in these areas. Simultaneous treatment with agmatine (50 mg/kg/day) prevented these morphological changes. Further measurement with HPLC showed that endogenous agmatine levels in the prefrontal cortex and hippocampus were significantly increased after 7‐day treatments with dexamethasone in a dose‐dependent manner. On the contrary, 21‐day treatment with glucocorticoids robustly reduced agmatine levels in these regions. The treatment‐caused biphasic alterations of endogenous agmatine levels were also seen in the striatum and hypothalamus. Interestingly, treatment with glucocorticoids resulted in a similar change of ADC protein levels in most brain areas to endogenous agmatine levels: an increase after 7‐day treatment versus a reduction after 21‐day treatment. These results demonstrated that agmatine has neuroprotective effects against structural alterations caused by glucocorticoids in vivo. The parallel alterations in the endogenous agmatine levels and ADC expression in the brain after treatment with glucocorticoids indicate the possible regulatory effect of these stress hormones on the synthesis and metabolism of agmatine in vivo.
Calcium channel subtypes differentially regulate fusion pore stability and expansion
Authors: Ardiles Alvaro O. , González‐Jamett Arlek M , Maripillán Jaime , Naranjo David , Caviedes Pablo , Cárdenas Ana María
Published: September 2007

Various studies have focused in the relative contribution of different voltage‐activated Ca2+ channels (VACC) to total transmitter release. However, how Ca2+ entry through a given VACC subtype defines the pattern of individual exocytotic events remains unknown. To address this question, we have used amperometry in bovine chromaffin cells. L, N, and P/Q channels were individually or jointly blocked with furnidipine, ω‐conotoxin GVIA, ω‐agatoxin IVA, or ω‐conotoxin MVIIC. The three channel types contributed similarly to cytosolic Ca2+ signals induced by 70 mmol/L K+. However, they exhibited different contributions to the frequency of exocytotic events and they were shown to differently regulate the final steps of the exocytosis. When compared with the other VACC subtypes, Ca2+ entry through P/Q channels effectively induced exocytosis, it decreased fusion pore stability and accelerated its expansion. Conversely, Ca2+ entry through N channels was less efficient in inducing exocytotic events, also slowing fusion pore expansion. Finally, Ca2+ entry through L channels inefficiently induced exocytosis, and the individual blockade of this channel significantly modified fusion pore dynamics. The distance between a given VACC subtype and the release sites could account for the differential effects of the distinct VACC on the fusion pore dynamics.
Prolyl hydroxylase inhibitors delay neuronal cell death caused by trophic factor deprivation
Authors: Lomb David J. , Straub Jennifer A. , Freeman Robert S.
Published: September 2007

Nerve growth factor (NGF) serves a critical survival‐promoting function for developing sympathetic neurons. Following removal of NGF, sympathetic neurons undergo apoptosis characterized by the activation of c‐Jun N‐terminal kinases (JNKs), up‐regulation of BH3‐only proteins including BcL‐2‐interacting mediator of cell death (BIM)EL, release of cytochromecfrom mitochondria, and activation of caspases. Here we show that two small‐molecule prolyl hydroxylase inhibitors frequently used to activate hypoxia‐inducible factor (HIF) – ethyl 3,4‐dihydroxybenzoic acid (DHB) and dimethyloxalylglycine (DMOG) – can inhibit apoptosis caused by trophic factor deprivation. Both DHB and DMOG blocked the release of cytochromecfrom mitochondria after NGF withdrawal, whereas only DHB blocked c‐Jun up‐regulation and phosphorylation. DHB, but not DMOG, also attenuated the induction of BIMELin NGF‐deprived neurons, suggesting a possible mechanism whereby DHB could inhibit cytochromecrelease. DMOG, on the other hand, was substantially more effective at stabilizing HIF‐2α and inducing expression of the HIF target genehexokinase 2than was DHB. Thus, while HIF prolyl hydroxylase inhibitors can delay cell death in NGF‐deprived neurons, they do so through distinct mechanisms that, at least in the case of DHB, are partly independent of HIF stabilization.
Developmental mercury exposure elicits acute hippocampal cell death, reductions in neurogenesis, and severe learning deficits during puberty
Authors: Falluel‐Morel Anthony , Sokolowski Katie , Sisti Helene M. , Zhou Xiaofeng , Shors Tracey J. , DiCicco‐Bloom Emanuel
Published: September 2007

Normal brain development requires coordinated regulation of several processes including proliferation, differentiation, and cell death. Multiple factors from endogenous and exogenous sources interact to elicit positive as well as negative regulation of these processes. In particular, the perinatal rat brain is highly vulnerable to specific developmental insults that produce later cognitive abnormalities. We used this model to examine the developmental effects of an exogenous factor of great concern, methylmercury (MeHg). Seven‐day‐old rats received a single injection of MeHg (5 μg/gbw). MeHg inhibited DNA synthesis by 44% and reduced levels of cyclins D1, D3, and E at 24 h in the hippocampus, but not the cerebellum. Toxicity was associated acutely with caspase‐dependent programmed cell death. MeHg exposure led to reductions in hippocampal size (21%) and cell numbers 2 weeks later, especially in the granule cell layer (16%) and hilus (50%) of the dentate gyrus defined stereologically, suggesting that neurons might be particularly vulnerable. Consistent with this, perinatal exposure led to profound deficits in juvenile hippocampal‐dependent learning during training on a spatial navigation task. In aggregate, these studies indicate that exposure to one dose of MeHg during the perinatal period acutely induces apoptotic cell death, which results in later deficits in hippocampal structure and function.
Necrostatin‐1 protects against glutamate‐induced glutathione depletion and caspase‐independent cell death in HT‐22 cells
Authors: Xu Xingshun , Chua Chu C. , Kong Jiming , Kostrzewa Richard M. , Kumaraguru Udayasankar , Hamdy Ronald C. , Chua Balvin H. L.
Published: September 2007

Glutamate, a major excitatory neurotransmitter in the CNS, plays a critical role in neurological disorders such as stroke and Parkinson’s disease. Recent studies have suggested that glutamate excess can result in a form of cell death called glutamate‐induced oxytosis. In this study, we explore the protective effects of necrostatin‐1 (Nec‐1), an inhibitor of necroptosis, on glutamate‐induced oxytosis. We show that Nec‐1 inhibits glutamate‐induced oxytosis in HT‐22 cells through a mechanism that involves an increase in cellular glutathione (GSH) levels as well as a reduction in reactive oxygen species production. However, Nec‐1 had no protective effect on free radical‐induced cell death caused by hydrogen peroxide or menadione, which suggests that Nec‐1 has no antioxidant effects. Interestingly, the protective effect of Nec‐1 was still observed when cellular GSH was depleted by buthionine sulfoximine, a specific and irreversible inhibitor of glutamylcysteine synthetase. Our study further demonstrates that Nec‐1 significantly blocks the nuclear translocation of apoptosis‐inducing factor (a marker of caspase‐independent programmed cell death)and inhibits the integration of Bcl‐2/adenovirus E1B 19 kDa‐interacting protein 3 (a pro‐death member of the Bcl‐2 family) into the mitochondrial membrane. Taken together, these results demonstrate for the first time that Nec‐1 prevents glutamate‐induced oxytosis in HT‐22 cells through GSH related as well as apoptosis‐inducing factor and Bcl‐2/adenovirus E1B 19 kDa‐interacting protein 3‐related pathways.
PERMANENT GENETIC RESOURCES: Isolation and characterization of microsatellite loci in the Mediterranean shore crab Carcinus aestuarii (Decapoda, Portunidae)
Authors: MARINO ILARIA A. M. , BARBISAN FEDERICA , GENNARI MICOL , BISOL PAOLO MARIA , ZANE LORENZO
Published: September 2007

We characterized nine polymorphic microsatellites in the Mediterranean shore crab Carcinus aestuarii (Decapoda: Portunidae). Microsatellites were isolated from a partial genomic library enriched for multiple motifs. All loci were polymorphic, with number of alleles ranging from two to 16 and a mean observed heterozygosity of 0.75. Seven loci were in Hardy–Weinberg equilibrium, and two showed weak heterozygote deficiency. No linkage disequilibrium was found between loci. In addition, we tested Hardy–Weinberg and linkage equilibrium of three Carcinus maenas loci, already reported to cross‐amplify in C. aestuarii. These molecular markers will be potentially useful to investigate genetic structure of this species.
Preventing Local Government Fiscal Crises: The North Carolina Approach
Authors: COE CHARLES K.
Published: September 2007

Some local governments face fiscal challenges due to mismanagement and declining economies. In particular, manufacturing states like Michigan and Ohio have been hard hit by the effects of international competition. To prevent fiscal distress from becoming a crisis, states exercise oversight over local government fiscal management. The three bond rating agencies consider the North Carolina oversight system a model. This paper discusses the North Carolina oversight system, including audit review, technical assistance, debt issuance, and power to take over the financial operations of distressed local units.
Structural Deficits and State Borrowing Costs
Authors: BENSON EARL D. , MARKS BARRY R.
Published: September 2007

This study examines the factors that affect the borrowing costs of state governments with specific attention being paid to the impact of state structural deficits (or fiscal imbalances) on borrowing costs. The findings for 1999–2000 suggest that interest costs for state competitively sold municipal securities reflect estimates of state structural deficits. States with a higher structural deficit were found to pay significantly higher interest costs. The evidence implies that bond ratings do not fully reflect the fiscal problems faced by state governments.
The Revenue Impact of Repeated Tax Amnesties
Authors: LUITEL HARI SHARAN , SOBEL RUSSELL S.
Published: September 2007

Proponents argue that tax amnesties raise revenue both in the short and long run, by bringing former nonfilers back into the tax system. Opponents contend that amnesties produce little short‐run revenue and weaken incentives for long‐run tax compliance. However, over the last 21 years, 27 states offered tax amnesties for a second or third time. While previous research has estimated the impact of specific tax amnesties, none have estimated how the impact changes when offered repeatedly. We find that these additional tax amnesties generate less short‐run revenue than predecessors and tend to magnify revenue losses associated with disincentives for long‐run tax compliance.
Business Management Reform in the Department of Defense in Anticipation of Declining Budgets
Authors: BROOK DOUGLAS A. , CANDREVA PHILIP J.
Published: September 2007

Business management reform efforts have been part of the U.S. Defense Department agenda for decades. Current reform efforts have explicitly established the goal of generating, harvesting, and reinvesting savings from business management reform to buy more capital items; that is, they have focused on a measurable reallocation from operating and support costs to investment within a given budget top line. Recent increases in the defense top line, largely related to the war on terrorism, are not likely to persist; in addition, an examination of the factors affecting the top line suggests that a decline in the near term is likely. An examination of current and past defense management reforms suggests that efficiency‐seeking business management reforms are not likely to generate sufficient resources to cover a budget decline. Instead, management reform should be sustained for reasons of stewardship and accountability.
An Examination of the Public Good Externalities of Professional Athletic Venues: Justifications for Public Financing?
Authors: SCHWESTER RICHARD W.
Published: September 2007

A review of the literature shows that stadiums and arenas are insignificant in terms of creating employment, engendering aggregate increases in local spending, and increasing per capita income levels. Public subsidies, then, may be better justified with reference to the nonpecuniary, public good externalities of professional athletic venues. This research examines whether the public good externalities of Baltimore's Oriole Park and Cleveland's Jacobs Field justify the use of taxpayer resources to finance such projects. This research finds that the public good externalities of Oriole Park and Jacobs Field are determinants of willingness to support the use of taxpayer resources to finance stadium projects.
Subnational Debt Swaps in Mexico, How Big Is Risk Exposure?
Authors: VELÁZQUEZ ALFONSO MENDOZA
Published: September 2007

Research and practice with derivative instruments by States and Municipalities in Mexico are virtually unexplored. This paper investigates the effect of interest rate jumps and financial contagion on the risk exposure of Subnational Government debt swaps in Mexico. Unconditional risk exposure measures of debt swaps are obtained by simulating a set of stochastic processes with jumps. Simulation results confirm that risk exposure of local debt swaps increases with Poisson discontinuities while a significant effect is observed after crisis contagion is accounted for.
Alumina/Zirconia Micro/Nanocomposites: A New Material for Biomedical Applications With Superior Sliding Wear Resistance
Authors: Bartolomé José F. , De Aza Antonio H. , Martín Antonia , Pastor José Y. , Llorca Javier , Torrecillas Ramón , Bruno Giovanni
Published: September 2007

In the present investigation, the sliding wear behavior is described for Al2O3/ZrO2 micro/nanocomposites and monolithic alumina of similar grain size under defined conditions of a constant sliding speed and different loads (20–150 N). Nano ZrO2 particles (1.7 vol%) were observed uniformly distributing throughout the composites, and most of them were located within the matrix alumina grains. The wear rate of the alumina and the micro/nanocomposites increased as the contact load increased and a clear transition in friction and wear behavior was observed in both materials. However, the nanocomposite wear resistance at low contact loads was one order of magnitude higher than that of the alumina. In the severe regime, no difference was observed among the materials. The low wear rate (10−7 mm3·(N·m)−1) along with low pullout indicates higher wear resistance of micro/nanocomposites in the mild regime compared with monolithic alumina. Based on the morphological observation of worn surfaces by scanning electron microscope and on residual stress analysis performed by neutron diffraction, some wear mechanisms of Al2O3–ZrO2 micro/nanocomposites are proposed. The high wear resistance of the nanocomposites is discussed in terms of fracture resistance properties and residual stress. Improvements in mechanical and tribological properties of these composites make them promising candidates for biomedical applications.
In‐Plane Cracking Behavior and Ultimate Strength for 2D Woven and Braided Melt‐Infiltrated SiC/SiC Composites Tensile Loaded in Off‐Axis Fiber Directions
Authors: Morscher Gregory N. , Yun Hee Mann , DiCarlo James A.
Published: September 2007

The tensile mechanical properties of ceramic matrix composites (CMC) in directions off the primary axes of the reinforcing fibers are important for the architectural design of CMC components that are subjected to multiaxial stress states. In this study, two‐dimensional (2D)‐woven melt‐infiltrated (MI) SiC/SiC composite panels with balanced fiber content in the 0° and 90° directions were tensile loaded in‐plane in the 0° direction and at 45° to this direction. In addition, a 2D triaxially braided MI SiC/SiC composite panel with a higher fiber content in the ±67° bias directions compared with the axial direction was tensile loaded perpendicular to the axial direction tows (i.e., 23° from the bias fibers). Stress–strain behavior, acoustic emission, and optical microscopy were used to quantify stress‐dependent matrix cracking and ultimate strength in the panels. It was observed that both off‐axis‐loaded panels displayed higher composite onset stresses for through‐thickness matrix cracking than the 2D‐woven 0/90 panels loaded in the primary 0° direction. These improvements for off‐axis cracking strength can in part be attributed to higher effective fiber fractions in the loading direction, which in turn reduces internal stresses on weak regions in the architecture, e.g., minicomposite tows oriented normal to the loading direction and/or critical flaws in the matrix for a given composite stress. Both off‐axis‐oriented panels also showed relatively good ultimate tensile strength when compared with other off‐axis‐oriented composites in the literature, both on an absolute strength basis as well as when normalized by the average fiber strength within the composites. Initial implications are discussed for constituent and architecture design to improve the directional cracking of SiC/SiC CMC components with MI matrices.
Formaldehyde‐, Benzene‐, and Xylene‐Sensing Characterizations of Zn–W–O Nanocomposite Ceramics
Authors: Ge Chunqiao , Xie Changsheng , Zeng Dawen , Cai Shuizhou
Published: September 2007

Zn–W–O nanocomposite ceramics with the whole concentration range (W at.%=0%, 1%, 5%, 25%, 50%, 75%, 95%, 99%, and 100%) have been fabricated by the sol–gel method, starting from zinc acetate dihydrate, ammonium tungstate, monoethanolamine (MEA), and anhydrous ethanol. Nanocomposites, that were sintered at 650°C in a conventional oven for 120 min were ultrasonically emulsified and coated on alumina ceramic tubes by dip coating. The microstructure and morphology of nanocomposites were characterized by X‐ray diffraction (XRD) and field emission scanning electron microscope (FESEM), respectively. The resistance and sensitivities to poisonous volatile organic compounds (PVOCS) were investigated on the static testing chamber. The XRD analysis of nanocomposites revealed the appearance of ZnWO4 with a monoclinic structure in the whole concentration range (1–99 at.%). The FESEM results showed that as‐prepared nanocomposites were composed of almost spherical particles with size range from 200 to 300 nm. Gas‐sensing properties of Zn–W–O nanocomposites ceramics, to formaldehyde, benzene, and xylene, were detected. The results showed that the ZnWO4 phase with high resistance almost did not respond to PVOCS. The appropriate amounts of ZnWO4 in ZnO‐rich samples and in WO3‐rich samples lend themselves to enhancement of gas‐sensing properties to PVOCS. The effect of ZnO, WO3, and ZnWO4 with a scheelite structure as solid acidic/alkaline catalysts on gas‐sensing property is also discussed.
Malaria − an overview
Authors: Tuteja Renu
Published: September 2007

Malaria is caused by protozoan parasites of the genus Plasmodium and is a major cause of mortality and morbidity worldwide. These parasites have a complex life cycle in their mosquito vector and vertebrate hosts. The primary factors contributing to the resurgence of malaria are the appearance of drug‐resistant strains of the parasite, the spread of insecticide‐resistant strains of the mosquito and the lack of licensed malaria vaccines of proven efficacy. This minireview includes a summary of the disease, the life cycle of the parasite, information relating to the genome and proteome of the species lethal to humans, Plasmodium falciparum, together with other recent developments in the field.
Vaccines against malaria – an update
Authors: Matuschewski Kai , Mueller Ann‐Kristin
Published: September 2007

Malaria vaccine discovery and development follow two principal strategies. Most subunit vaccines are designed to mimic naturally acquired immunity that develops over years upon continuous exposure to Plasmodium transmission. Experimental model vaccines, such as attenuated live parasites and transmission‐blocking antigens, induce immune responses superior to naturally acquired immunity. The promises and hurdles of the different tracks towards an effective and affordable vaccine against malaria are discussed.
Drug‐resistant malaria − an insight
Authors: Hyde John E.
Published: September 2007

Despite intensive research extending back to the 1930s, when the first synthetic antimalarial drugs made their appearance, the repertoire of clinically licensed formulations remains very limited. Moreover, widespread and increasing resistance to these drugs contributes enormously to the difficulties in controlling malaria, posing considerable intellectual, technical and humanitarian challenges. A detailed understanding of the molecular mechanisms underlying resistance to these agents is emerging that should permit new drugs to be rationally developed and older ones to be engineered to regain their efficacy. This review summarizes recent progress in analysing the causes of resistance to the major antimalarial drugs and its spread.
Helicases − feasible antimalarial drug target for Plasmodium falciparum
Authors: Tuteja Renu
Published: September 2007

Of the four Plasmodium species that cause human malaria, Plasmodium falciparum is responsible for the most severe form of the disease and this parasite is developing resistance to the major antimalarial drugs. Therefore, in order to control malaria it is necessary to identify new drug targets. One feasible target might be helicases, which are important unwinding enzymes and required for almost all the nucleic acid metabolism in the malaria parasite.
The importance of polymerization and galloylation for the antiproliferative properties of procyanidin‐rich natural extracts
Authors: Lizarraga D. , Lozano C. , Briedé J. J. , van Delft J. H. , Touriño S. , Centelles J. J. , Torres J. L. , Cascante M.
Published: September 2007

Grape (Vitis vinifera) and pine (Pinus pinaster) bark extracts are widely used as nutritional supplements. Procyanidin‐rich fractions from grape and pine bark extract showing different mean degrees of polymerization, percentage of galloylation (percentage of gallate esters) and reactive oxygen species‐scavenging capacity were tested on HT29 human colon cancer cells. We observed that the most efficient fractions in inhibiting cell proliferation, arresting the cell cycle in G2 phase and inducing apoptosis were the grape fractions with the highest percentage of galloylation and mean degree of polymerization. Additionally, the antiproliferative effects of grape fractions were consistent with their oxygen radical‐scavenging capacity and their ability to trigger DNA condensation–fragmentation.
A role of monocyte chemoattractant protein‐4 (MCP‐4)/CCL13 from chondrocytes in rheumatoid arthritis
Authors: Iwamoto Takuji , Okamoto Hiroshi , Kobayashi Shu , Ikari Katsunori , Toyama Yoshiaki , Tomatsu Taisuke , Kamatani Naoyuki , Momohara Shigeki
Published: September 2007

We studied the role of monocyte chemoattractant (MCP)‐4/CCL13 in the pathogenesis of rheumatoid arthritis (RA). MCP‐4 was highly expressed in cartilage from RA patients. Interferon‐γ significantly stimulated MCP‐4/CCL13 production in human chondrocytes, and this effect was enhanced in combination with interleukin‐1β or tumor necrosis factor‐α. MCP‐4/CCL13 induces the phosphorylation of extracellular signal‐regulated kinase in fibroblast‐like synoviocytes and activates cell proliferation, and PD98059 completely inhibits these effects. These data suggest that interferon‐γ in combination with interleukin‐1β/tumor necrosis factor‐α activates the production of MCP‐4/CCL13 from chondrocytes in RA joints, and that secreted MCP‐4/CCL13 enhances fibroblast‐like synoviocyte proliferation by activating the extracellular signal‐regulated kinase mitogen‐activated protein kinase cascade.
The viral SV40 T antigen cooperates with dj2 to enhance hsc70 chaperone function
Authors: Salma Athanasia , Tsiapos Apostolos , Lazaridis Ioannis
Published: September 2007

Simian virus 40 large T antigen is a J‐domain‐containing protein with multiple functions. Among its numerous activities, T antigen can bind heat shock cognate 70 (hsc70) but the biological significance of this interaction has not been fully understood. Here, we show that T antigen can act as an hsc70 co‐chaperone enhancing the protein‐folding ability of the hsc70 chaperone machine. We also show that T antigen exerts its function in collaboration with the mammalian homologue of DnaJ. Moreover, we show that the participation of T antigen in the hsc70 chaperone machine has cell‐type‐specific characteristics.
Respiratory modulation of cardiovascular rhythms before and after short‐duration human spaceflight
Authors: Verheyden B. , Beckers F. , Couckuyt K. , Liu J. , Aubert A. E.
Published: September 2007

Aim:  Astronauts commonly return from space with altered short‐term cardiovascular dynamics and blunted baroreflex sensitivity. Although many studies have addressed this issue, post‐flight effects on the dynamic circulatory control remain incompletely understood. It is not clear how long the cardiovascular system needs to recover from spaceflight as most post‐flight investigations only extended between a few days and 2 weeks.

Methods:  In this study, we examined the effect of short‐duration spaceflight (1–2 weeks) on respiratory‐mediated cardiovascular rhythms in five cosmonauts. Two paced‐breathing protocols at 6 and 12 breaths min−1 were performed in the standing and supine positions before spaceflight, and after 1 and 25 days upon return. Dynamic baroreflex function was evaluated by transfer function analysis between systolic pressure and the RR intervals.

Results:  Post‐flight orthostatic blood pressure control was preserved in all cosmonauts. In the standing position after spaceflight there was an increase in heart rate (HR) of approx. 20 beats min−1 or more. Averaged for all five cosmonauts, respiratory sinus dysrhythmia and transfer gain reduced to 40% the day after landing, and had returned to pre‐flight levels after 25 days. Low‐frequency gain decreased from 6.6 (3.4) [mean (SD)] pre‐flight to 3.9 (1.6) post‐flight and returned to 5.7 (1.3) ms mmHg−1 after 25 days upon return to Earth. Unlike alterations in the modulation of HR, blood pressure dynamics were not significantly different between pre‐ and post‐flight sessions.

Conclusion:  Our results indicate that short‐duration spaceflight reduces respiratory modulation of HR and decreases cardiac baroreflex gain without affecting post‐flight arterial blood pressure dynamics. Altered respiratory modulation of human autonomic rhythms does not persist until 25 days upon return to Earth.
GENERALIZED SHORTEST PATH AND TRAFFIC EQUILIBRIUM IN COMPLEX TRANSPORTATION NETWORKS
Authors: ZHAO HUI , GAO ZIYOU
Published: September 2007

Shortest path plays an important role in the study of complex networks. But in real transportation systems, choosing the shortest path may not be the best way for the drivers. Based on the traffic equilibrium theory, we generalize the concept of shortest path. Flux distribution is also investigated by using the generalized concept on various types of complex networks. We find that the flux differs little in all the edges of lattice while in small-world and scale-free networks, the flux distribution follows a power law, and in the random network, the flux distribution has an exponential tail. We consider lattice may be the optimal topology in design a transportation network.
A NUMERICAL INVESTIGATION OF THE CRITICAL PHASE OF RANDOM BOOLEAN NETWORKS
Authors: CHEN SHAN-TARNG , TSENG HSEN-CHE , WANG SHU-CHIN , LI PING-CHENG
Published: September 2007

Our numerical simulation first displays exponential increase of the mean number of attractors with N for K = 2,3,4 and 50≦ N ≦350. The mean length of attractors also increases exponentially with N for K = 2, but increases linearly with N for K = 3,4. We further found the larger the K the larger S/N value; which yields the results that the mean length and the mean number of attractors of critical random Boolean networks will decrease with larger K.
INFLUENCE OF PUMP DIRECTION IN ALL-OPTICAL GAIN-CLAMPED FIBER RAMAN AMPLIFIER
Authors: CHEN ZHIQIANG , NING JIPING , HAN QUN
Published: September 2007

The influence of pump direction in all-optical gain-clamped fiber Raman amplifier using the directional couplers in feedback loop is demonstrated. The isolator direction decided the lasing direction in feedback loop. The comparison of performance in two lasing directions for both schemes is shown. It is concluded that the forward pumping configuration with forward lasing has better gain clamping performance and noise performance.
FTIR STUDY OF THE OXYGEN REDUCTION REACTIONS ON Sm0.5Sr0.5CoO3
Authors: WU QI-HUI , ABERNATHY HARRY , CHENG ZHE , LIU MEILIN
Published: September 2007

The oxygen reduction on solid oxide fuel cell cathode electrode, Sm 0.5 Sr 0.5 CoO 3, was studied by using emission Fourier transform infrared spectroscopy (FTIR). Superoxide [Formula: see text] species was detected with appearance of an IR peak at wavenumber about 1124 cm-1. Moreover, we interpreted for the first time that there would be a close relationship between the baseline shift of IR spectra and the oxygen vacancy concentration (OVC) of the samples. The downward baseline shift of IR spectra is due to the decrease of OVC in the bulk, while, the increase of the OVC in the bulk would cause the upward baseline shift.
PLATING OF COPPER LAYERS ON POLYIMIDES USING ELECTROLESS PLATING BY SURFACE MODIFICATION
Authors: JI EUN SUN , KIM YOUNG HWAN , KANG YONG CHEOL , KANG YOUNG SOO , AHN BYUNG HYUN
Published: September 2007

This work describes electroless deposition of copper layers onto a polyimide (PI) film. The film was modified by etching with 1.0 M KOH solution treatment, and an activated Ag thin film was developed on this surface using 0.1 M AgNO 3. The Cu layers were coated on the activated surface of polyimide films by electroless plating method. The thickness and surface morphology of Cu layers on the PI films were characterized with atomic force microscopy. The surface properties of PI film were identified with contact angle measurements.
SURFACE OXIDATION OF Ti-6Al-4V FOR BIO-IMPLANT APPLICATION
Authors: BISWAS A. , BHATTACHARJEE U. , MANNA I. , DUTTA MAJUMDAR J.
Published: September 2007

The present study aims at enhancing the wear resistance and biocompatibility of Ti -6 Al -4 V by forming a thin layer of oxide. Surface oxidation has been carried out by controlled heating of the surface of Ti -6 Al -4 V substrate in air at the temperature ranging from 400–600°C and time from 25–60 h. The phase formed under thermal oxidation was predominantly the rutile and anatase phase. The thickness of the oxide layer varied from 1.5–7.0 μm. The microhardness on the surface was significantly improved as compared to the as-received substrate. Both the corrosion resistance property and biocompatibility were improved.
EFFECTS OF ANNEALING AND Ar INTERCALATION ON GLASS TRANSITION IN C60 FILMS
Authors: WU JIAN , GU MIN , ZHANG LILI , YU YAO , CHEN XIN , TANG TONG B.
Published: September 2007

C 60 films were fabricated by vacuum sublimation and studied with dielectric spectroscopy regarding glass transition. With annealing, the dielectric loss peaks decreased in height, and the apparent activation energy deduced from their frequency dependence dropped in magnitude. The peaks, broad and asymmetrical, were fitted with Ngai's correlated-states model. The calculated value of the correlation constant β increased after annealing, which may be explained by the reduction in extrinsic dipole density. Some annealed films were further charged with Ar under high pressure, and found to have suppressed transition temperature and activation energy, attributable to the negative pressure effect of intercalation. Freshly charged films exhibited a feature near 137 K in their impedance spectra, probably due to domains of exceptionally high Ar concentration.
THE STUDY ON THE ELECTRIC FIELD EFFECT IN THE La0.8Ca0.2MnO3/PbZr0.2Ti0.8O3/Si HETEROSTRUCTURE
Authors: WEI ZHANG WEI , FENG WANG LI , QING ZHOU YU , MING ZHU
Published: September 2007

A detailed quantitative investigation of the current–voltage (I–V) relationship under the low and the high electric field in the La 0.8 Ca 0.2 MnO 3/ PbZr 0.2 Ti 0.8 O 3/ Si heterostructure over a wide range of temperature was performed. The effective mobility and carrier concentration were then calculated through the electric field effect theory. The differential mobility can be modulated and enhanced significantly by the gate voltage in the vicinity of the metal–insulator-transition temperature. The carrier concentration is proportional to the applied gate voltage. At the room temperature the carrier concentration is found to be 2.5 × 10-9 under 10 V bias and remains almost unchanged at different temperatures.
Li-DOPING EFFECT ON THE CATHODOLUMINESCENT PROPERTIES OF Y2O3:Eu3+ PHOSPHORS
Authors: BAE J. S. , YOON J. H. , PARK S. K. , KIM J. P. , JEONG E. D. , WON M. S. , JEONG J. H. , SHIM K. S. , YANG H. K. , YI S. S.
Published: September 2007

Influence of lithium doping on the crystallization, the surface morphology, the chemical states and the luminescent properties of Y 2 O 3: Eu 3+ phosphors was investigated. The structural, surface morphology characteristics and chemical states of the phosphors were analyzed by using X-ray diffraction (XRD), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS), respectively. The crystallinity, the surface morphology, and the cathodoluminescence (CL) of phosphors highly depended on the Li doping. The relationship between the crystalline and morphological structures and the luminescent properties was studied, and Li + doping affected not only the crystallinity but also the luminescent brightness of Y 2 O 3: Eu 3+ phosphors. In particular, the incorporation of the Li + ion into the Y 2 O 3 lattice could induce remarkable increase in the CL intensity. The enhanced photoluminescence brightness with Li doping may result both from the improved crystallinity leading to higher oscillating strengths for the optical transitions, and the increased surface area due to the larger particle sizes. The strongest emission intensity was observed with Li doped Y 2 O 3: Eu 3+ ceramics whose brightness was increased by a factor of 1.8 in comparison with that of Y 2 O 3: Eu 3+ ceramics.
LONG-TERM OPERATION TESTS OF ORGANIC SOLID-STATE SOLAR CELLS
Authors: SHIOKAWA HIROKI , YOKOYAMA MASAAKI , HIRAMOTO MASAHIRO
Published: September 2007

The long-term operation tests of two types of solid-state organic photovoltaic (OPV) cells, p–n heterojunction type cells and p–i–n junction type cells, were performed. In both cells, a drastic decrease in photocurrent within 1 h was observed in air. This rapid decrease was revealed to be caused by oxygen molecules which act as a electron trap in the electron transporting organic layer. Initial decrease of photocurrent was effectively suppressed under high vacuum (10-7 Torr). In the case of a p–n type cell, the decrease in short-circuit photocurrent was only 15% even under prolonged light irradiation of 260 h.
EFFECT OF SURFACE TREATMENT ON THE PROPERTIES OF WOOL FABRIC
Authors: KAN C. W. , YUEN C. W. M. , CHAN C. K. , LAU M. P.
Published: September 2007

Wool fiber is commonly used in textile industry, however, it has some technical problems which affect the quality and performance of the finished products such as felting shrinkage, handle, lustre, pilling, and dyeability. These problems may be attributed mainly in the presence of wool scales on the fiber surface. Recently, chemical treatments such as oxidation and reduction are the commonly used descaling methods in the industry. However, as a result of the pollution caused by various chemical treatments, physical treatment such as low temperature plasma (LTP) treatment has been introduced recently because it is similarly capable of achieving a comparable descaling effect. Most of the discussions on the applications of LTP treatment on wool fiber were focused on applying this technique for improving the surface wettability and shrink resistance. Meanwhile, little discussion has been made on the mechanical properties, thermal properties, and the air permeability. In this paper, wool fabric was treated with LTP treatment with the use of a non-polymerizing gas, namely oxygen. After the LTP treatment, the fabrics low-stress mechanical properties, air permeability, and thermal properties were evaluated and discussed.
STEREO PHOTOGRAPHY OF ATOMIC ARRANGEMENT AND ATOMIC-ORBITAL ANALYSIS BY TWO-DIMENSIONAL PHOTOELECTRON SPECTROSCOPY
Authors: MATSUI FUMIHIKO , MATSUSHITA TOMOHIRO , GUO FANG ZHUN , DAIMON HIROSHI
Published: September 2007

The circular dichroism of photoelectron forward focusing peak rotation around the incident-light axis reflects the orbital angular momentum of the excited core level and is inversely proportional to the distance between the emitter and scatterer atoms. This is the basis for the stereo photograph of the atomic arrangements. These rotations are also found in the case of the valence band excitation. The rotation for the 2pxy band of graphite was about twice those from 2s and 2pz bands, corresponding to the difference in the orbital angular momentum quantum number of each band. Simultaneously, photoelectron intensity from the bottom of the 2s band was observed at the Γ point of every other Brillouin zone reflecting the photoelectron structure factor that corresponds to the interference of photoelectron waves from 2s atomic orbitals within a unit cell. The origin of the dual behavior that appeared in the observation of a local angular momentum from a delocalized valence band is discussed.
DEVELOPING SELECTIVE OXIDATION CATALYSTS OF LIGHT ALKANES: FROM FUNDAMENTAL UNDERSTANDING TO RATIONAL DESIGN
Authors: FU GANG , YI XIAODONG , HUANG CHUANJING , XU XIN , WENG WEIZHENG , XIA WENSHENG , WAN HUI-LIN
Published: September 2007

Selective oxidation of light alkanes remains to be a great challenge for the wider use of alkanes as feedstocks. To achieve high activity and at the same time high selectivity, some key issues have to be addressed: (1) the stability of the desired products with respect to the reactants; (2) the roles of the active components in the catalysts, the structure and the functionality of the active centers; (3) the reducibility of the metal cations, the Lewis acid sites and their synergic effects with the basic sites of the lattice oxygen anions; (4) spatial isolation of the active centers; and (5) the mechanisms for the formation and transformation of the intermediates and their kinetic controls. In this contribution, we took selective oxidation of propane to acrolein as our target reaction, and reviewed mainly our own work, trying to provide some thinking and answers to these five questions.
PREPARATION AND CHARACTERIZATION OF Ag(CORE)/SiO2(SHELL) NANOPARTICLES
Authors: CHA HWA JIN , KIM YOUNG HWAN , CHA HYUN GIL , KANG YOUNG SOO
Published: September 2007

Ag nanoparticles were synthesized by using thermal decomposition of Ag +–oleate complex. The mean size of Ag nanoparticle was confirmed as 10 nm with transmission electron microscopy (TEM). The crystal structure and optical property of Ag nanoparticles were studied with X-ray powder diffraction (XRD) and UV–vis spectroscopy, respectively. The Ag nanoparticles were used as seeds for Ag (core)/ SiO 2(shell) nanocomposite particles. TEM images of Ag (core)/ SiO 2(shell) nanocomposite particles showed that silver core was coated with 15 nm thickness of SiO 2 shell. The thickness of SiO 2 shells could be conveniently controlled by changing the concentration of sol–gel precursor or reaction time. The composition of Ag (core)/ SiO 2(shell) nanocomposite particle was investigated with energy-dispersive X-ray (EDX) spectrometer.
SYNTHESIS AND DEGRADATION OF THE PbS NANOPARTICLE PHOSPHORS EMBEDDED IN SiO2 (SiO2:PbS)
Authors: DHLAMINI M. S. , TERBLANS J. J. , NTWAEABORWA O. M. , SWART H. C.
Published: September 2007

PbS nanoparticle phosphors embedded in SiO 2 were synthesized at room temperature by the sol–gel method. The as-prepared SiO 2:0.134 mol% PbS nanoparticles were ground and annealed in atmosphere. Changes in the cathodoluminescence (CL) brightness and the surface chemical composition of the SiO 2:0.134 mol% PbS nanoparticle powders were investigated using a Fiber Optics PC2000 spectrometer for CL and Auger Electron Spectroscopy (AES) and X-ray Photoelectron Spectroscopy (XPS) for the surface chemical analysis. The chemical composition of the powders was analyzed by an energy-dispersive spectrometer (EDS). The CL intensity decreased when the powders were irradiated with a beam of electrons at 2 keV energy and a beam current density of 54 mA/cm2 in an ultra-high vacuum chamber at oxygen ( O 2) pressures ranging between 5 × 10-8 and 2 × 10-7 Torr for several hours. The O 2 Auger peak-to-peak height (APPH) decreased as the CL intensity decreased. XPS analysis on the degraded spot showed the development of characteristic SiO , SiO x, and elemental Si peaks on the low-energy side of the SiO 2 peak. The desorption of O 2 from the surface, which resulted in a decrease in the CL intensity is attributed to the dissociation of SiO 2 into elemental Si and O 2 by the electron bombardment. The degradation was less severe at higher oxygen pressures. PbSO 4 was also formed on the surface during the electron beam degradation process.
EFFECT OF SLOW HEATING AND COOLING ON THE INTERDIFFUSION OF THIN FILMS
Authors: JOUBERT H. D. , TERBLANS J. J. , SWART H. C.
Published: September 2007

Interdiffusion parameters are often extracted from depth profiles of the interface of annealed thin films by measuring the annealing time of the sample as well as the distance over which interdiffusion took place. The annealing time is usually taken as the time from the moment the sample enters the oven to the exact moment the sample is removed from the oven. However, diffusion does not start and stop at these points, as the temperature of the sample does not change instantaneously. Any calculation performed with the instantaneous and therefore erroneous time will result in incorrect diffusion parameters extracted from the depth profiles. The influence of the extended heating period is studied by solving Fick's second law numerically and employing three distinct heating profiles in the calculations, namely instantaneous, actual, and linear. The results indicate a clear difference between the first two calculated depth profiles. Using these calculations and some experimental results, a method that employs linear heating and cooling of a sample is proposed for studying the interdiffusion of fast diffusing elements (with low activation energies).
THE ADSORPTION OF Au ON Si(111)-7 × 7 SURFACE: A FIRST-PRINCIPLES STUDY
Authors: ZHOU YINGHUI , WU QI-HUI , LI SHUPING , KANG JUNYONG
Published: September 2007

The initial stage of Au adsorption on the Si (111)-7 × 7 surface has been investigated by the first-principles calculations. Different configurations have been considered and the high coordination sites were determined as the most possible places for the Au adsorption. The diffusion barriers for Au atoms on the Si surface have also been evaluated. The results indicated that the Au atoms could diffuse from the top of the Si rest atoms to the high coordination sites only by overcoming a small barrier of 0.11 eV.
SIZE-DEPENDENT ELASTIC PROPERTIES OF Ni NANOFILMS BY MOLECULAR DYNAMICS SIMULATION
Authors: YANG ZHENYU , ZHAO YA-PU
Published: September 2007

Size-dependent elastic properties of Ni nanofilms are investigated by molecular dynamics (MD) simulations with embedded atom method (EAM). The surface effects are considered by calculating the surface relaxation, surface energy, and surface stress. The Young's modulus and yield stress are obtained as functions of thickness and crystallographic orientation. It is shown that the surface relaxation has important effects on the the elastic properties at nanoscale. When the surface relaxation is outward, the Young's modulus decreases with the film thickness decreasing, and vice versa. The results also show that the yield stresses of the films increase with the films becoming thinner. With the thickness of the nanofilms decreasing, the surface effects on the elastic properties become dominant.
MOLECULAR DYNAMICS SIMULATION OF ADHESION FORCES IN A DIPALMITOYLPHOSPHATIDYLCHOLINE MEMBRANE
Authors: YIN JUN , ZHAO YA-PU
Published: September 2007

Adhesion forces of Dipalmitoylphosphatidylcholine (DPPC) membrane in the gel phase are investigated by molecular dynamics (MD) simulation. In the simulations, individual DPPC molecules are pulled out of DPPC membranes with different rates and we get the maximum adhesion forces of DPPC membrane. We find that the maximum adhesion forces increase with pull rate, from about 400 to 700 pN when pull rates are from 0.001 to 0.03 nm/ps. We analyze the relationship between pull rate and adhesion forces of different origins using Brownian dynamics and notice that viscosity of solvent plays an important role in adhesion forces. Then we simulate the motion of a single DPPC molecule in solvent and it elucidates that the maximum drag force is almost linear with respect to the pull rate. We use Stokes' relation to describe the motion of a single DPPC molecule and deduce the effective length of a DPPC molecule. Conformational analyses indicate that the free energy variation of a DPPC molecule inside and outside of the DPPC membrane is an essential part of adhesion energy.