bluuebunny/crossref_metadata_2025 huggingface dataset:
Study of Homocysteine Concentration in Coronary Heart Disease Patients and Comparison of Two Determination Methods
Authors: Doncheva Nadezhda , Penkov Alexandar , Velcheva Anita , Boev Micho , Popov Bojidar , Niagolov Yuri
Published: March 2007

Introduction: Elevated total homocysteine (tHCY) is a known risk factor for atherosclerotic vascular disease, but the mechanism is not well understood. The study was designed to estimate tHCY concentration and other risk factors in coronary heart disease (CHD) males, evaluating two different methods for tHCY measurement: gas chromatography-mass spectrometry (GC-MS) method and competitive immunoassay method. Materials and Methods: Fifty men, mean age 53.9 years with CHD and a body mass index (BMI) >25.0, were examined for tHCY concentrations, lipids, blood glucose, uric acid, complete blood picture and erythrocyte sedimentation rate and high-sensitive C-reactive protein (hsCRP). Biochemical and hematological indices were determined by routine methods, hsCRP – by immunometric chemiluminescence method, and tHCY – by two different methods: a gas chromatographic method, using GC-MS and a competitive immunoassay method on an Immulite device. Results: The mean values of the lipids showed moderate dyslipidemia while the other parameters were within reference range. Mean BMI was 28.5 ± 0.42. Values of tHCY determined by the immunoassay method were 13.2 ± 0.95 µmol/l, and determined by GC-MS – 14.6 ± 1.09 µmol/l. We found a linear agreement between the DPC and GC-MS sets of measurements (r = 0.87, p ≤ 0.001). The median tHCY concentrations measured by immunoassay werelower than those measured with GC-MS, but differences were insignificant. An agreement between the competitive immunoassay and the GC-MS method evaluated by the Bland and Altman method was found. tHCY was >15 µmol/l in 12 patients as determined by the competitive immunoassay, and in 15 patients by the GC-MS method. tHCY levels were between 10 and 15 µmol/l in 24 patients by the immunoassay and in 29 patients by the GC-MS method. Twenty-four percent of the patients with CHD have an ‘increased risk’ with tHCY >15 µmol/l, and 48% are in the ‘gray zone’ with tHCY levels between 10 and 15 µmol/l. Conclusions: 40.8% of the studied patients had increased tHCY levels, not associated with the other lipid and nonlipid risk factors. The closest conformity between GC-MS and immunoassay methods was observed for serum tHCY concentrations. The between-method comparison revealsthat the above-mentioned methods can be used interchangeably.
Possible Role of sarA in Dehydroepiandrosterone-Mediated Increase in Staphylococcus aureus Resistance to Vancomycin
Authors: Plotkin Balbina J. , Konaklieva Monika
Published: March 2007

Background: Dehydroepiandrosterone (DHEA), a steroid present throughout life, can induce an increase in resistance to vancomycin in methicillin-sensitive and methicillin-resistant clinical isolates of Staphylococcus aureus. Methods: The in vitro effect of DHEA on vancomycin killing of S. aureus with mutations in sarA and/or agr was determined by standard microtiter protocols and time to kill determinations. Results: Of the isolates tested, the strain with a deletion in sarAderived from a DHEA- responsive parent was not protected from vancomycin killing by DHEA. However, DHEA significantly (p < 0.01) slowed the rate of vancomycin killing of sarA–. Conclusion: These data indicate that sarA may play a role in DHEA-mediated protection from vancomycin killing of S. aureus.
In vitro AN69 and Polysulphone Membrane Permeability to Ceftazidime and in vivo Pharmacokinetics during Continuous Renal Replacement Therapies
Authors: Isla Arantxazu , Gascón Alicia R. , Maynar Javier , Arzuaga Alazne , Sánchez-Izquierdo José Antonio , Pedraz José Luis
Published: March 2007

Background: Ceftazidime is a third-generation cephalosporin almost entirely eliminated by glomerular filtration and dose reductions are essential in patients with renal impairment. The physicochemical and pharmacokinetic properties of ceftazidime make it susceptible to be eliminated by continuous renal replacement therapies (CRRT), but there is little clinical information to guide the correct administration in patients undergoing these techniques. Methods: In vitro procedures were carried out in three different fluids, using AN69 or polysulphone membranes. Four patients entered the in vivo study. Two patients received 1,000 mg every 6 h and the other two 2,000 mg every 6 h. Concentrations of ceftazidime were measured by high-performance liquid chromatography. Results: No differences were detected in thesieving coefficients (Sc) or saturation coefficients (Sa)between membranes during continuous venovenous hemofiltration (CVVH) or continuous venovenous hemodiafiltration (CVVHD). Sc-Sa values were close to 1 when Ringer’s lactate was used as ceftazidime vehicle, but were lower in plasma samples (p < 0.05). In patients, the Sc-Sa was 0.93 ± 0.06 and correlated well with the unbound fraction (0.86 ± 0.08). The contribution of CRRT to ceftazidime clearance was higher in anuric patients than in nonanuric patients. Conclusions: No differences were shown in vitro in the Sc obtained with both membranes during CVVH or the Sa obtained during CVVHD. The contribution of clearance by CRRT to total clearance is clearly dependent on the renal function. The administration of ceftazidime every 6 h could be associated with unnecessarily high trough levels which increase the risk of drug nephrotoxicity. Nonanuric patients undergoing CRRT need higher ceftazidime doses to reach adequate plasma concentrations against pathogens isolated in the critically ill.
Retrospective Evaluation of Sequential Outpatient Chemotherapy for Advanced Gastric Cancer
Authors: Satoh Seiji , Kawashima Kazuhiko , Matsumoto Shigemi , Hasegawa Suguru , Okabe Hiroshi , Nomura Akinari , Yoshibayashi Hiroshi , Watanabe Go , Nagayama Satoshi , Fukushima Masanori , Sakai Yoshiharu
Published: March 2007

Background/Aim: Due to the recent development of several promising chemotherapeutic agents, such as S-1, irinotecan (CPT-11) and paclitaxel, response rates for advanced gastric cancer to chemotherapy have improved. Thus far, however, the efficacy and survival benefits of sequential chemotherapy using these agents have not been evaluated. An additional benefit of outpatient sequential chemotherapy, that is, without hospitalization, would be its contribution to the maintenance of patients’ social activities. The aim of this study was to retrospectively evaluate sequential outpatient chemotherapy for advanced gastric cancer. Patients and Methods: Patients with metastatic/recurrent gastric cancer treated with sequential outpatient chemotherapy were analyzed retrospectively. The sequential treatment consisted of S1-based chemotherapy as first-line therapy, low-dose CPT-11/CDDP as second-line therapy and weekly paclitaxel administration as third-line therapy. Results: A series of 32 patients was enrolled in this study. During the sequential chemotherapy, all patients were treated at the outpatient ward of Kyoto University Hospital without hospitalization. The overall response rate was 37.5% and the median survival time was 523 days (95% confidence interval: 323–723 days). The progression-free survival for the three therapies was 135 days for S-1, 148 days for low-dose CPT-11/CDDP and 57 days for paclitaxel. Grade 4 neutropenia was observed in 1 patient (3.1%), and there were no treatment-related deaths. Univariate analysis showed that factors with significant impact on survival were pathological type (intestinal vs. diffuse), clinical response (responder vs. non-responder) and prior chemotherapy. Factors with p values <0.1, including pathological type, clinical response, prior chemotherapy and age (>75 vs. ≤75 years), were evaluated by multivariate analysis, which disclosed that clinical response and patient age were significantly related to patient prognosis. Conclusion: In terms of survival and maintenance of social activities of patients, outpatient sequential chemotherapy appears to be both feasible and effective for advanced gastric cancer. Although prospective analysis of sequential chemotherapy is difficult because of its complex treatment protocol, clinical trials to assess the survival benefits of second-line chemotherapy for advanced gastric cancer are clearly warranted.
Age-Related Changes in Intramyocellular Lipid in Humans by in vivo 1H-MR Spectroscopy
Authors: Nakagawa Yoshinao , Hattori Masaaki , Harada Kuniaki , Shirase Ryuji , Bando Michio , Okano Goroh
Published: March 2007

Background: It is considered that the increasing intramyocellular lipid (IMCL) affects health risks and muscle attenuation. Though body fat increases significantly with age in lean humans, it is not known whether IMCL increases or not. In this study, we investigated the changes with age in IMCL concentrations in skeletal muscles using 1H-MR spectroscopy and studied them in relation to body fat percentage, waist-hip ratio, and blood components. Methods: Twenty-four lean young (age 21.2 ± 1.9, BMI 21.5 ± 1.8) and 23 lean old (age 70.9 ± 2.4, BMI 21.7 ± 1.3) subjects took part in the study. Subjects were grouped by gender into age- and BMI-matched young and old groups. The 1H-MRS was obtained from the tibialis anterior (TA), medial gastrocnemius (MG) and soleus (SOL) muscles. Results: The IMCL content in SOL and MG in the old was found to be higher (p < 0.01) than that in the young. No age difference in IMCL content in TA was found. IMCL concentrations in SOL were higher than those in MG and TA in the order of SOL > MG > TA (p < 0.01). IMCL content correlated significantly with waist-hip ratio in all skeletal muscles. A significant relationship was observed between percent body fat and IMCL in TA and MG (p < 0.05). However, no correlation was found between IMCL content in each muscle and BMI. The IMCL content in all skeletal muscles significantly correlated with HbA1c, triglyceride, total cholesterol and LDL cholesterol concentrations. Conclusion: These results suggest that increased IMCL in both lean older men and women might be related to body composition, blood lipids and lipoprotein profiles, and that this might affect muscle attenuation.
rhGH Treatment in Corticosteroid-Treated Patients
Authors: Simon Dominique
Published: March 2007

Children and adolescents treated for chronic diseases have non-specific metabolic abnormalities that lead to decreased growth velocity and abnormal body composition, including severe osteoporosis, muscle wasting and increased fat mass. Glucocorticoid (GC) therapy plays a major role in the complex pathogenesis of these metabolic abnormalities. Recombinant human growth hormone (rhGH) therapy was introduced a few years ago to reduce the severe disease- and GC-related metabolic consequences of juvenile idiopathic arthritis, other chronic diseases, and renal transplantation. Short- and mid-term rhGH treatment has consistently proved effective in overcoming GC-induced growth suppression, with a marked interindividual variability in the growth response to rhGH treatment. Safety of rhGH treatment, concerning the progression of the disease and glucose tolerance, was good. Prolonged follow-up until achievement of adult height is needed to better evaluate the impact of rhGH treatment on growth and body composition and the long-term consequences of hyperinsulinism.
Infertility in Cryptorchidism Is Linked to the Stage of Germ Cell Development at Orchidopexy
Authors: Hadziselimovic Faruk , Höcht Burckhard , Herzog Bruno , Buser Mauro W.
Published: March 2007

Background: Cryptorchidism represents the most common endocrine disease in boys, with infertility frequently observed in unilateral as well as bilateral forms. In this study, we examined the role of Ad (dark) spermatogonia for fertility in cryptorchid boys. The hypothesis to be proven was that boys lacking Ad spermatogonia will develop infertility despite a successful orchidopexy at an early age. Methods: To estimate total sperm count, one of the most predictive parameters of male fertility, we analyzed the ejaculatein 218 cryptorchid men and correlated it with the developmental stage of their germ cells at the time of successful surgery. Results: Abnormal sperm concentration (<40 × 106/ejaculate) was found in half of the patients under the study. 47.5% of unilateral and 78% of bilateral cryptorchid males had their sperm concentration in the infertility range according to the WHO standards. If transformation into Ad spermatogonia had occured, age-related differences in the fertility outcome was observed. The younger the unilateral cryptorchid boys were at surgery, the higher their sperm count. Age-related difference was not found in the group of cryptorchid men having had no A dark spermatogonia at time of surgery, indicating that in this group a successful orchidopexy is insufficient to prevent infertility development and, in particular, the development of azoospermia. Conclusion: The presence of Ad spermatogonia at surgery is an excellent prognostic parameter for future fertility. Cryptorchid boys lacking these cells will develop infertility despite successful orchidopexy at an early age.
Domain-Specific Improvement of Cognition on Memantine in Patients with Alzheimer’s Disease Treated with Rivastigmine
Authors: Riepe Matthias W. , Adler Georg , Ibach Bernd , Weinkauf Birgit , Tracik Ferenc , Gunay Ibrahim
Published: March 2007

Objective: Cholinergic therapy is used in mild-to-moderate Alzheimer’s disease (AD) and antiglutamatergic therapy in moderate-to-severe AD. Global scales, as commonly used in clinical trials, blur specifics of disease progression and drug effects. The objective was to assess combination therapy of rivastigmine plus memantine by specific neuropsychological tests in patients with mild-to-moderate AD. Methods: 12-week-short multicenter open-label pilot study. Ninety patients with mild-to-moderate AD already on stable medication with rivastigmine (3–6 mg b.i.d.) additionally received memantine for 12 weeks. Subscales of the Alzheimer’s Disease Assessment Scale (ADAS-cog), the Mini-Mental State Examination (MMSE) and additional neuropsychological tests (e.g. span tasks, semantic fluency) were assessed. Results: The scores in the ADAS-cog memory subscale, the MMSE score, and digit span and semantic fluency significantly improved on combination therapy. Conclusion: Memory improvement was correlated with ADAS-cog memory score at baseline and inversely with age at onset of treatment. The data suggest that improvement on combination therapy results from an improvement of attention/executive function with secondary memory improvement, which will need to be confirmed in a subsequent double-blind study on a larger number of patients.
Hepatitis C in Chronic Kidney Disease: Predialysis Patients Present More Severe Histological Liver Injury than Hemodialysis Patients?
Authors: Lemos Lara B. , Perez Renata M. , Lemos Marcelo M. , Lanzoni Valéria P. , Draibe Sergio A. , Silva Ivonete S. , Silva Antonio Eduardo B. , Ferraz Maria Lucia G.
Published: March 2007

Background: The characteristics of hepatitis C virus (HCV) infection in predialysis patients are poorly understood and they could be different from hemodialysis patients. Aims: To evaluate the demographics, laboratory and histological characteristics of chronic HCV infection in predialysis patients and to compare them with those observed in hemodialysis patients. Methods: Thirty-nine predialysis patients with chronic HCV infection were compared to HCV-infected hemodialysis patients (ratio of 1:3) in terms of demographics, laboratory and histological characteristics. The fibrosis progression rate (FPR) was calculated as the ratio between fibrosis stage and duration of infection. Results: Predialysis patients were older (57 ± 10 vs. 45 ± 12 years; p < 0.001), presented a higher proportion of elevated alanine aminotransferase (71.8 vs. 41.0%; p = 0.001) and aspartate aminotransferase (64.1 vs. 26.5%; p < 0.001), a higher proportion of interface hepatitis (66.7 vs. 47%; p = 0.033) and more advanced fibrosis (71.8 vs. 16.2%; p = 0.001). Among patients with estimated duration of infection, predialysis patients presented a longer duration of infection (22 vs. 6 years; p < 0.001) and no difference in FPR was observed between groups (p = 0.692). Conclusion: Although predialysis patients with HCV infection present more severe histological injury than hemodialysis patients, this finding probably reflects a longer duration of infection with no evidence supporting that hepatitis C presents a more aggressive course in this group.
Treatment of Delusions in Dementia with Lewy Bodies – Response to Pharmacotherapy
Authors: Fischer Corinne , Bozanovic Radenka , Atkins Jana H. , Rourke Sean B.
Published: March 2007

Background:Delusions are clinically important symptoms in dementia with Lewy bodies (DLB). The purpose of this review is to examine the level of evidence for treatment of delusions in DLB. Methods:To achieve this objective Medline was searched. Studies were included in the review if they were prospective, separated delusions from hallucinations and were tested in patients with DLB. Results:The review yielded a total of six studies. Although all studies showed effectiveness, only one study using rivastigmine had an adequate patient sample size and used a randomized controlled design. Conclusion:Further studies are required before a definitive conclusion can be reached about effective treatments.
HSPG2 Gene C/A Polymorphism Does Not Confer Susceptibility to Alzheimer’s Disease in Chinese
Authors: Wang Binbin , Jin Feng , Yang Ze , Lu Zeping , Zheng Chenguang , Wang Li
Published: March 2007

Human HSPG2 participates in the formation of amyloid and tau aggregation in Alzheimer’s disease (AD). HSPG2 gene is located on a susceptibility region to late-onset AD (LOAD), and considered as a candidate gene for LOAD because of its function and location. We performed an association study between the HSPG2 BamH I polymorphism C/A of intron 6 and LOAD on 104 patients and 127 healthy controls of Chinese origin. The C allele was more prominent in LOAD patients than in controls, though the difference was not statistically significant. Likewise with the stratification of APOE Ε4 status, no statistical difference was observed between cases and controls. Our findings suggest that this polymorphism may not represent an additional genetic risk factor for LOAD.
Development of a Representative Unit Cell Model for Bi-axial NCF Composites
Authors: Oakeshott J.L. , Iannucci L. , Robinson P.
Published: March 2007

Composite materials fabricated from non-crimp fabric (NCF) are showing potential in primary aerospace components and structures. They can be used in common RFI, RIFT, and RTM manufacturing processes, and are showing promise to replace traditional pre-preg systems. The composite designer hence needs a technique, which can be used to predict the elastic properties of the NCF laminate including manufacturing defects from these infusion processes. The present study develops a representative unit cell (RUC) model of the NCF blanket, which can include potential variability in the NCF structure. Representative unit cells have been developed to predict the two- and three-dimensional mechanical properties in the bi-axial NCF composite. The model is based on the two-dimensional methods of Naik and Scida for woven fiber composites, incorporating the elastic anisotropy theory of Lekhnitskii to extend the predictions to three dimensions. Continuous tow layers with uniform thickness and fiber volume fraction are assumed, and the effects of crimp due to stitching and surrounding resin regions are simulated. The input data are based on measurements and observations of a ±45° carbon-epoxy NCF composite having a 63% fiber volume fraction and less than 1% voids. Output from the model is obtained in terms of the stiffness and compliance matrices as well as traditional engineering properties. For the tensile and compressive moduli, comparisons with data from the carbon/epoxy NCF composite show the values are over-predicted by 11.5—11.6% in tension and 13.5—13.9% in compression. Improved predictions are obtained using a simple stiffness model that allows for different behaviors of the resin as continuous layers or gaps between tows. The resin layers, compared to the resin as gaps, significantly decrease the in-plane moduli, and the model is considered to simulate local through-thickness shear deformation in the resin layers.
Observation of Permeability Dependence on Flow Rate and Implications for Liquid Composite Molding
Authors: Sun Kyoung Kim  , Daniel Isaac M.
Published: March 2007

The variation of permeability with the flow rate has been investigated. This variation is demonstrated by conducting specially designed experiments. The results show that permeability increases significantly as the flow rate increases. The implication of this observation is that the permeability measured under some given conditions is not always applicable to the actual molding situation. Furthermore, the permeability is not constant over both the space and time domains during the filling process. In order to take such dependence into account, a permeability model and an estimation technique for determining the coefficients of the model are proposed.
Numerical Simulation of Compressible Flow with Phase Change of Filling Stage in Injection Molding
Authors: Changyu Shen , Lixia Wang , Qian Li
Published: March 2007

The filling stage in injection molding has important effects on the final properties and quality of the parts. It is significant to predict the history of flow and heat transfer in the filling stage accurately and thus predict the part properties and quality. The modeling is based on the generalized Hele–Shaw flow of a compressible viscous fluid under non-isothermal conditions with consideration of the effects of compressibility and phase change. A hybrid FEM/FDM method combined with a control volume method was adopted to simulate the filling stage in plastics injection molding. A program was developed and compressible flow analysis of the filling stage was implemented using Visual C++. Comparison of numerical and experimental results verified the numerical algorithm and program of the compressible filling simulation. The numerical analysis also indicated that the compressibility of the material had important effects on flow field of imbalance molds.
Methods to Reduce the Print-through Phenomenon on the Surface of FRP
Authors: Lin Huei-Jeng , Liao Chin-I , Jiang Ren-Li
Published: March 2007

The reflected image on the surface of the fiber-reinforced plastic (FRP) often presents twists and wrinkles. This phenomenon is called print-through phenomenon (PTP) in this investigation and the lines present on the material surface are called print-through lines (PTL). Earlier studies and experimental observations indicate that PTP is related to the non-uniform inner stress in the gel coating layer of the FRP. The non-uniform inner stress is caused by the various shrinkages of the plastic matrix and fibers of the fiber layers during the laminating process. So the main idea to reduce PTP is to reduce or uniform the non-uniform inner stress in the gel coating layer of the FRP. Several methods can be used to reduce PTP and two of them are investigated in this paper. One is removing atmospheric pressure before the plastic matrix of the fiber layers hardens. The other method is inserting a core-Mat layer into the Mat layers during laminating the FRP.

Removing atmospheric pressure before the plastic matrix hardens can remove the influence of atmospheric pressure on causing the inner stress of the gel coating layer. Once the inner stress of the gel coating layer is reduced, PTP on the surface of the FRP can be eased off. Inserting a core-Mat layer into the Mat layers will form a buffer zone which can uniform the inner stress in the gel coating layer of the FRP. Therefore, PTP on the surface of the FRP can be eased off. To verify the present contentions, some experiments and qualitative analysis were performed. Both experimental and analysis results show that the PTP on the surface of FRP can be reduced by the present methods.
Drop Weight Impact Properties of (CO) Injection Molded Short Glass Fiber/Short Carbon Fiber/Polyamide 6 Hybrid Composites
Authors: Solomon S. , Bakar A. Abu , Ishak Z. A. Mohd , Leong Y. W. , Ishiaku U. S. , Hamada H.
Published: March 2007

Polyamide 6 (PA 6) composites with short glass fiber (GF)/short carbon fiber (CF) hybrid fiber reinforcement were produced using two types of injection molding techniques, i.e., the conventional and co-injection molding machines. In the latter, sandwich skin-core hybrid composites were produced. The fiber volume fraction for all formulations was fixed at 0.07. The composites were subjected to drop weight impact tests, to determine their impact strength, impact energy, ductility index (DI) and ductility ratio (DR). It was observed that the PA 6 formulation exhibited the highest impact strength and impact energy values whereas carbon fiber/PA 6 (CF/PA 6) exhibited the highest DI and DR values. The carbon fiber skin/glass fiber core/PA 6 (CFS/GFC/PA 6) sandwich skin-core hybrid composites showed the highest impact energy and impact strength values among hybrids. The glass fiber skin/carbon fiber core/PA 6 (GFS/CFC/PA 6) hybrids on the other hand showed the highest DI and DR values among hybrids. Failure mechanisms in the matrix and composites, assessed by scanning electron microscope (SEM), were discussed in relation to the effects of fiber incorporation and its effects on the ductility of the composites, with particular emphasis on the hybrid composites.
Progressive Failure Analysis of Cross-ply Laminated Composite Plates by Finite Element Method
Authors: Pal P. , Bhattacharyya S. K.
Published: March 2007

The progressive failure analysis of laminated composite plates under transverse static loading has been carried out in the linear and elastic range. The laminated composite plate has been modeled using eight-noded isoparametric plate bending elements. The first-order shear deformation theory has been employed to account for the shear flexibility characteristics through the thickness direction of a composite laminate. A shear correction factor has been considered to reduce discrepancy between the assumed constant shear strain and the actual parabolic variation of the shear strain in the transverse direction. The mid surface of the laminate has been considered as the reference plane in the present formulation. After the failure of the weakest ply, the stiffness is reduced by either fiber failure or matrix failure. The stiffness of failed lamina has been totally discarded and other existing laminae are considered to remain unchanged after the weakest ply failure. The strength of the laminate at the same point is evaluated again to see if the laminate can carry additional load. This ply-by-ply analysis progresses until the ultimate strength of the laminate is reached. The results in terms of first-ply failure load obtained in the present investigation have been compared with those available in published literature. A parametric study has been carried out to estimate the influence of stacking sequence, fiber orientation, layer thickness, aspect ratio and the number of layers in the laminated composite plates on the prediction of ultimate failure load.
Modification of Cyanate Resin by Nanometer Silica
Authors: Wang Junlong , Liang Guozheng , Zhu Baolin
Published: March 2007

Several nanometer silicas, which were purchased or prepared by sol-gel method at different contents, have been used to modify Bisphenol-A cyanate resin (BADCy) in this article. The curing conditions and processing technology have been established. Meanwhile, the reactivity of this system and the structure of SiO2/BADCy composites are investigated by transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). Moreover, the reasonable mechanism is also illustrated based on these results. It is found that BADCy can be reinforced and toughened simultaneously by nanometer silica with different size ranging from 15 to 45 nm, which were dispersed in the BADCy macromolecular networks. When the content of nanometer silica was 2-4%, the effect of reinforcement and toughness was on the best levels.
Torsional Buckling of Multi-walled Carbon Nanotubes Subjected to Torsional Loads
Authors: Wang X. Y. , Wang X.
Published: March 2007

The torsional buckling of an individual multi-walled carbon nanotube under two different loading conditions is studied in this article. The multiple shell model is adopted and the effects of van der Waals forces between adjacent nanotubes are taken into account. An examination with an individual double-walled carbon nanotube shows that the effect of the change of interlayer spacing on the torsional buckling force can be neglected if only the innermost radius is larger than a certain value. Under this condition, single buckling equations are derived and explicit formulas for the critical torsional loads in terms of the buckling modes are obtained. It is found that the critical torsional load of a multi-walled carbon nanotube with torque exerted on the outermost tube is higher than that of the same multi-walled carbon nanotubes under the torques being proportionally applied to each individual layer of the multi-walled carbon nanotubes. For thin multi-walled carbon nanotubes with large radii, the critical torque linearly scales with its thickness, but the critical shear force (per unit length) of the multi-walled carbon nanotubes uniformly twisted along the cross section does not increase as its layer number (thickness) increases, which is due to the interlayer slips between adjacent nanotubes.
Elastic Wave Scattering in Porous Unidirectional Fiber-reinforced Composites
Authors: Hasheminejad Seyyed M. , Avazmohammdi Reza
Published: March 2007

Scattering of elastic waves in unidirectional fiber-reinforced porous–matrix composites is studied using novel features of Biot classic model for dynamic poroelasticity. The method of separation of variables along with the appropriate wave field expansions, the pertinent boundary conditions, and the translational addition theorems for cylindrical wave functions are employed to develop a closed-form solution in form of infinite series. The analytical results are illustrated with numerical examples in which a pair of rigid or elastic fibers are insonified by a plane fast compressional or shear wave at end-on/broadside incidence. The effects of incident wave frequency, proximity of the two fibers, fiber material properties and angle of incidence on the far-field backscattered radial and shearing stress amplitudes are examined. Particular attention has been focused on multiple scattering interactions in addition to the slow wave coupling effects which is known to be the primary distinction of the scattering phenomenon in poroelasticity from the classical elastic case. Limiting cases are considered and fair agreements with well-known solutions are established.
Effect of Hygrothermal Shock Cycles on Interlaminar Shear Strength of Hybrid Composites
Authors: Ray P. K. , Mula S. , Mohanty U. K. , Ray B. C.
Published: March 2007

The present study aims to assess the interlaminar shear strength (ILSS) of interply woven fabric glass/carbon hybrid composites under the influence of a fluctuating humid environment. The ILSS values have been used for quantification of mechanical degradation. The effects of fluctuating environment on moisture sorption as well as the degradation kinetics have been assessed. It is seen that the ILSS shows a gradual degradation over a period of time. It has been observed that the ILSS scales inversely with crosshead velocities. This is attributed to the presence of alternating strong and weak interfaces and the differences in their moisture sorption tendencies.
Buckling of Metal-Matrix Composite Plate with a Square Hole
Authors: Yeh Hsien-Yang , Le Ryan Minh , Yeh Hsien-Liang
Published: March 2007

The buckling of laminated metal-matrix composite (MMC) plates with a central square cutout were analyzed under compressive biaxial loading using the finite element approach. The MMC plates displayed some interesting buckling patterns and initial buckling shapes when subjected to different combination of hole sizes and boundary conditions. In the case of anti-symmetric, free-free boundary conditions, the MMC plates with central square cutout resist higher buckling loads as the hole size increased. Two laminated stacking sequences [90/0/0/90]2 [45/-45/-45/45]2 were used in this study. For the same hole size, plate aspect ratio, and boundary conditions, the results showed that the critical buckling behavior of the plates were primarily influenced by the edge boundary conditions rather than by the laminated stacking sequences. The overall critical buckling analysis indicated that plates with clamped boundary conditions will take higher compressive loads than that of simply supported boundary conditions by a ratio of 2 to 1.
Effects of the Strain Rate Variation on the Interlaminar Stresses of the Thick Angle-ply Laminates
Authors: Ding Shurong , Tong J. W. , Huo Y. Z. , Shen M.
Published: March 2007

In this paper, for the thick AS4/PEEK angle-ply laminate [±25]s4, the interlaminar stresses for four different strain rates are computed and investigated. The three-dimensional distribution plots at different interfaces are given. According to the interlaminar stress results for four different strain rates, the effects of the strain rates on the interlaminar stresses at different interfaces are elucidated. The absolute values of the interlaminar shear stresses τzx at the interfaces +25°/-25° and -25°/+25° increase along with increase of strain rates. The effects of the strain rates on the interlaminar shear stresses τzy at the interfaces are similar. For the interlaminar normal stresses at the interfaces +25°/-25° and -25°/+25°, if the stresses are tensile ones, their values rise along with increment of the strain rates; however, if they are compressive stresses, the contrary effects exist. Furthermore, the variation circumstances of the interlaminar stresses along the thickness are studied, and the interlaminar stresses for four strain rates at this location are analyzed. It can be obtained that the interlaminar stresses closer to the free edges at the interfaces are most evidently influenced by the strain rates.
How much is too much? Oligosymptomatic presentation after 11.5 g of diphenhydramine
Authors: Frick Sonia , Roos Markus , Fattinger Karin
Published: March 2007

We report the case of a 47-year-old male obese Caucasian patient presenting 2 hours after ingestion of 11.5 g of diphenhydramine. Despite this excessive overdose, he showed only a few hours of impaired consciousness and no further symptoms. A diphenhydramine plasma concentration of 15 352 nmol/L was measured 8 hours after the overdose ingestion. A heterogeneous CYP2D6 extensive metabolizer genotype excludes a pharmacokinetic explanation for this unusually oligosymptomatic presentation. However, the patient suffered from longstanding, refractory depression despite numerous treatment attempts with various drugs, pointing to the possibility of decreased pharmacodynamic responsiveness for therapeutic and toxic effects. Human & Experimental Toxicology (2007) 26, 131-133
Effects of sub-chronic oral cyanide on endothelial function in rabbit aortic rings
Authors: Ozolua R.I. , Okolie N.P. , Ebeigbe A.B. , Karikari N.
Published: March 2007

We have investigated how the endothelium affects vascular responses following sub-chronic low dose cyanide administration. Cyanide exists in low levels in cassava foods, which are widely consumed in tropical Africa. Adult rabbits were administered 0.38 mg/kg per day KCN po for 25 days, and responses of the isolated aortic rings to noradrenaline (NA), calcium chloride (Ca2+) and acetylcholine (ACh) were measured in vitro in the presence and absence of the endothelium. In order to establish that the dose was not toxic, animal weight, some haematological indices, plasma alanine aminotransferase (ALT), and aspartate aminotransferase (AST) were measured. Results show that endothelium denudation significantly (P <0.05) attenuates NA-induced contraction in rings from cyanide-treated rabbits. There was a similar reduction in response in Ca2+-depleted NA-precontracted endothelium-denuded aortic rings from cyanide-treated rabbits. Endothelium-denuded rings from cyanide-treated rabbits showed significantly (P <0.05) enhanced relaxation to ACh. In rings from control animals, the responses to NA and Ca2+ were not significantly altered, whether in the presence or absence of the endothelium. There were no significant changes in the studied toxicological indices. We conclude that endothelial compromise is necessary for low-dose sub-chronic cyanide-induced to alter vascular reactivity to NA and ACh. Human & Experimental Toxicology (2007) 26, 105-110
Skin decontamination of mustards and organophosphates: comparative efficiency of RSDL and Fuller's earth in domestic swine
Authors: Taysse L. , Daulon S. , Delamanche S. , Bellier B. , Breton P.
Published: March 2007

Research in skin decontamination and therapy of chemical warfare agents has been a difficult problem due to the simultaneous requirement of rapid action and non-aggressive behaviour. The aim of this study was to compare the performance of two decontaminating systems: the Canadian Reactive Skin Decontaminant Lotion (RSDL) and the Fuller's Earth (FE). The experiment was conducted with domestic swine, as a good model for extrapolation to human skin. RSDL and FE were tested against sulphur mustard (SM), a powerful vesicant, and VX, a potent and persistent cholinesterase inhibitor. When used 5 min after contamination, the results clearly showed that both systems were active against SM (10.1 mg/cm2) and VX (0.06 mg/cm2). The potency of the RSDL/sponge was statistically better than FE against skin injury induced by SM, observed 3 days post-exposure. RSDL was rather more efficient than FE in reducing the formation of perinuclear vacuoles and inflammation processes in the epidermis and dermis. Against a severe inhibition (67%) of plasmatic cholinesterases induced by VX poisoning, the potencies of the RSDL/sponge and FE were similar. Both systems completely prevented cholinesterase inhibition, which indirectly indicates a prevention of toxic absorption through the skin. Human & Experimental Toxicology (2007) 26, 135-141
Inhibition of radiation-induced clastogenicity by Aegle marmelos (L.) Correa in mice bone marrow exposed to different doses of γ-radiation
Authors: Jagetia G.C. , Venkatesh P.
Published: March 2007

The frequency of micronucleated polychromatic (MPCE), normochromatic erythrocytes (MNCE), and polychromatic/normochromatic erythrocyte ratio (PCE/NCE), was studied in the bone marrow of mice orally administered with 0, 200, 225, 250, 275 and 300 mg/kg body weight of hydroalcoholic leaf extract of Aegle marmelos (AME). Treatment of mice with AME, once daily for 5 consecutive days, before exposure to 2 Gy resulted in a significant decline in the frequency of MPCE when compared to the non-drug-treated irradiated control. The greatest reduction in MPCE was observed for 250 mg/kg body weight AME, accompanied by the highest polychromatic erythrocyte to normochromatic erythrocyte ratio, in comparison with the non-drug-treated irradiated control. Therefore, further studies were carried out using this dose of AME, where the animals were administered with 250 mg/kg body weight of AME before exposure to 0, 0.5, 1, 2, 3 and 4 Gy of γ-radiation and evaluated at 12, 24, 36 and 48 hours post-irradiation. Whole body irradiation of mice to different doses of γ-radiation resulted in a dose-dependent increase in the frequency of MPCE at all post-irradiation times. Treatment of 250 mg/kg AME orally (p.o.) before irradiation significantly reduced the frequency of MPCE at all post-treatment times. The frequency of MPCE increased with time, reached a peak level at 24 hours, and declined thereafter. The occurrence of MNCE has also shown a pattern similar to MPCE, except that the MNCE frequency reached a peak level by 48 hours. The AME significantly reduced the frequency of MNCE at all post-irradiation times, when compared to the non-drug-treated irradiated group. Treatment of mice with AME before exposure to different doses of γ-radiation resulted in the inhibition of a radiation-induced decline in the PCE/NCE ratio, when compared with the concurrent irradiated controls. To gain insight into the mechanism of action, AME was tested for its antioxidant effects in cell-free chemical systems using H2O 2/FeSO4 to generate hydroxyl (◦OH) radicals, which were measured by a fluorescent probe, 2V, 7V-dichlorofluorescin diacetate (DCFH/DA). Xanthine/xanthine oxidase was used to generate superoxide (O2◦-) anion radical, which was measured by a fluorescent probe dihydroethidium (DHE). AME significantly reduced fluorescence in a concentration dependent manner, indicating its efficacy to scavenge free radicals. Our results demonstrate that one of the mechanism of reduction in the radiation-induced DNA damage in mice bone marrow by AME may be due to scavenging of free radicals and elevation in the antioxidant status, as previously reported. Human & Experimental Toxicology (2007) 26, 111-124
Protective effects of N-acetylcysteine on peroxidative changes of the fetal rat lungs whose mothers were exposed to cigarette smoke
Authors: Basyigit I. , Tugay M. , Dilioglugil M.O. , Yildiz F. , Maral H. , Sozubir S.
Published: March 2007

Background: This experimental study investigated the protective effects of N-acetylcysteine (NAC) on peroxidative changes in fetal lungs in the offspring of rats exposed to cigarette smoke. Methods: Thirty fetal rats used for analysis, were divided into three groups as follows: control group (n = 10), whose mothers were exposed to fresh air; group I (n=10), whose mothers were exposed to cigarette smoke; and group II (n=10), whose mothers were exposed to cigarette smoke and given 10 mg/kg per day NAC. In groups I and II, smoke exposure was started 4 weeks before the pregnancy, and continued to the 14th day of pregnancy, and in Group II, NAC was administered intraperitoneally for 14 days. The mothers and their fetuses were decapitated on the 14th day of pregnancy. Malondialdehyde (MDA) and glutathione (GSH) levels were determined in the lung tissues of fetuses to determine the oxidant-antioxidant balance. Results: While tissue MDA levels in Group I were found significantly higher than the control group (129.7±65.4 versus 63.4±15.4 nmol/100 mg protein, P <0.05), GSH levels were significantly lower (17.1±7.3 versus 45.4±8.1 nmol/mg protein, P <0.01). Furthermore, in Group II, MDA levels were significantly lower (56.9± 20.6 versus 129.7±65.4 nmol/100 mg protein, P <0.05), and GSH levels were significantly higher (34.57±10.7 versus 17.1±7.3 nmol/mg protein, P <0.0001) when compared with Group I. No statistically significant difference was found in tissue MDA and GSH levels between Group II and the control group (P >0.05). Conclusions: These results suggest that smoke exposure during pregnancy causes oxidative damage in fetal lungs. This smoke-induced damage might be prevented by NAC. Human & Experimental Toxicology (2007) 26, 99-103
Pediatric lisinopril ingestions reported to Texas poison control centers
Authors: Forrester M.B.
Published: March 2007

Lisinopril is not recommended for use by young children. This study attempted to identify factors associated with serious outcomes in pediatric lisinopril ingestions. Cases for this study were lisinopril ingestions by children age ≤5 years reported to Texas poison control centers during 1998- 2005. The percentage of cases involving serious medical outcomes was identified for selected variables and evaluated for statistical significance by calculating the rate ratio (RR) and 95% confidence interval (CI). Of 691 total cases, 26 (3.8%) involved a serious outcome. Higher serious outcome rates were found with a max imum dose of >4 mg/kg (RR: 2.54, CI: 0.05-25.62), or > 80 mg (RR: 7.85; CI: 1.73-29.29),or five or more tablets (RR: 8.18; CI: 2.73-22.54), or the patient was already at or en route to a health care facility when the poison control center was contacted (RR: 13.93; CI: 3.68-77.78),or referred to a health care facility by the poison control center (RR: 33.49; CI: 9.04-194.94). The management of patients with severe outcomes was more likely to involve health care facilities. This information is useful for drafting triage guidelines for the management of pediatric lisinopril ingestions. Human & Experimental Toxicology (2007) 26 , 83- 89
Stable Rotation of a Parametrically Excited Double Pendulum
Authors: Nagamine Takuo , Sato Yuichi , Koseki Yoshikazu
Published: March 2007

The rotation of a double pendulum with a dc motor installed between the first and second pendulums was investigated using both experiments and numerical computations. The first pendulum can rotate freely around one end, while the second pendulum is attached to the other end of the first pendulum; the dc motor attached to the first pendulum causes the second pendulum to rotate with respect to the first pendulum. We clarify that there is a range of rotation speed in which the first pendulum rotates at the same, one-half, or one-third of the rotation speed of the second pendulum, and the stable rotation of the double pendulum is realized without torque control of the dc motor and report the characteristics of the stable rotation of the double pendulum.
Longitudinal Motion Control of a High-Speed Supercavitation Vehicle
Authors: Vanek Bálint , Bokor József , Balas Gary J. , Arndt Roger E.A.
Published: March 2007

This article focuses on theoretical developments in modeling and control of High-Speed Supercavitating Vehicles (HSSV). A simplified model of longitudinal dynamics is developed for control, and a dynamic inversion based inner-loop control technique is proposed to handle the switched, time-delay dependent behavior of the vehicle. Two outer-loop control schemes are compared for guidance level tracking. Various aspects of disturbance characteristics and actuator dynamics are investigated and analyzed.
Free Vibration of Stiffened Conoidal Shell Roofs with Cutouts
Authors: Hota Sasank Sekhar , Chakravorty Dipankar
Published: March 2007

A finite element code is developed for analyzing the free vibration characteristics of a stiffened conoidal shell by combining an eight noded curved shell element with a three noded curved beam element. The code is validated by solving problems available in the literature and comparing the present results with established ones. A number of problems are further solved where the size of the cutouts and their positions with respect to the shell centre are varied for different edge constraints of full and truncated conoids. The effects of these parametric variations on the fundamental frequencies are studied and discussed in details. The results are furnished as figures and tables, which may be readily used by practicing engineers dealing with stiffened conoids with cutouts central or eccentric.
Behavioral Investigation of a Nonlinear Nonideal Vibrating System
Authors: El-Badawy Ayman A.
Published: March 2007

This work demonstrates that a simple, reduced-order, nonlinear model provides an effective analytical tool for the treatment of source-structure interactions by applying the theory to an actual structure and developing the appropriate model. The equations of motion were analyzed using perturbation analysis to determine the frequency response of the system in the vicinity of the primary resonance. The theoretical and experimental frequency response curves were compared to deduce the effective nonlinearity coefficient, and it is shown that, at certain critical speeds, the excitation source is severely limited by the structural vibrations generated.