bluuebunny/crossref_metadata_2025 huggingface dataset:
Oral Supplementation of Majun Baladar Ameliorates Antioxidant Enzyme Activities in Cerebral Ischaemic Damage
Authors: Yousuf Seema , Atif Fahim , Hoda Nasrul , Ahmad Muzamil , Saleem Sofiyan , Ishrat Tauheed , Khan M. Badruzzaman , Ahmad Abdullah Shafique , Islam Fakhrul
Published: August 2007

Abstract:   Majun Baladar (MB), a traditional herbal formulation of the Unani system of medicine, was studied for its efficacy against cerebral ischaemia‐induced oxidative damage in hippocampus and associated neurobehavioural deficits. Adult male Wistar rats were divided into four groups. The first group was sham, the second group was ischaemic (MCAO: middle cerebral artery occluded) and the third group was a MB pre‐treated ischaemic group (MCAO + MB). The fourth group was given MB (1.05 g/kg) orally for 15 days as a drug control. The middle cerebral artery was occluded for 2 hr and reperfused for 22 hr in the ischaemic as well as the drug pre‐treated group. The activity of the various enzymatic antioxidants like glutathione peroxidase, glutathione reductase, glutathione S‐transferase and non‐enzymatic antioxidants, glutathione along with levels of lipid peroxidation were evaluated. Cerebral ischaemic rats showed elevated level of lipid peroxidation and decreased levels of various antioxidants significantly over sham values. As a result of MB pre‐treatment, the level of lipid peroxidation was found to be significantly depleted as compared to the ischaemic group. Furthermore, depleted levels of glutathione and the activity of glutathione peroxidase, glutathione S‐transferase and glutathione reductase were restored significantly in MB treated group. Majun Baladar exhibited a significant improvement in neurobehavioural activities in the drug pre‐treated animals as compared to the ischaemic group as evidenced by the grip strength test, Rota‐Rod and video path analysis. The results of the present study provide baseline information regarding the neuroprotective efficacy of MB and also open a window for a potent therapeutic use of this traditional herbal Unani medicine.
Silymarin Prevents Palmitate‐Induced Lipotoxicity in HepG2 Cells: Involvement of Maintenance of Akt Kinase Activation
Authors: Song Zhenyuan , Song Ming , Lee David Y. W. , Liu Yanze , Deaciuc Ion V. , McClain Craig J.
Published: August 2007

Abstract:   Whereas adipocytes have a unique capacity to store excess free fatty acids in the form of triglyceride in lipid droplets, non‐adipose tissues, such as liver, have a limited capacity for storage of lipids. Saturated long‐chain fatty acids, such as palmitate, are the major contributors to lipotoxicity. Silymarin is a mixture of flavonolignans, extracted from the milk thistle (Silibum marianum). Its hepatoprotective properties have been studied both in vitro and in vivo; however, its effect on palmitate‐induced lipotoxicity has not been investigated. The objective of this study was to investigate (i) whether silymarin could protect HepG2 cells from palmitate‐induced cell death in an in vitro model, and (ii) possible mechanisms involved in this hepatoprotective role of silymarin. HepG2 cells were treated with palmitate in the absence or presence of silymarin and supernatants or cell lysates were collected at varying time‐points. Cell death was assayed by measuring DNA fragmentation, caspase‐3 activity and lactate dehydrogenase release. Lipid peroxidation was assessed by measuring malondialdehyde and 4‐hydroxyalkenals. Akt kinase activity was also measured. Incubation with palmitate caused significant death in HepG2 cells. Palmitate incubation did not cause significant changes in reactive oxygen species production or intracellular glutathione content, but markedly inhibited Akt kinase activity. Pre‐treatment of HepG2 cells with silymarin prevented palmitate‐induced inhibition of Akt kinase activity and attenuated cell death. Our results suggest that silymarin may be an effective agent in protecting hepatocytes from saturated fatty acids‐induced cell death. These data also provide a further rationale for exploration of the use of silymarin in the treatment of non‐alcoholic steatohepatitis.
Pharmacokinetics of Two Randomized Trials Evaluating the Safety and Efficacy of Indinavir, Saquinavir and Lopinavir in Combination with Low‐Dose Ritonavir: The MaxCmin1 and 2 Trials*
Authors: Justesen Ulrik S. , Fox Zoe , Pedersen Court , Cahn Pedro , Gerstoft Jan , Clumeck Nathan , Losso Marcello , Peters Barry , Obel Niels , Castagna Antonella , Dragsted Ulrik B. , Lundgren Jens D. ,   on behalf of the MaxCmin1 and 2 trial groups
Published: August 2007

Abstract:   Our objective was to identify possible differences in protease inhibitor plasma concentrations between and within three protease inhibitor regimens (indinavir, saquinavir and lopinavir all in combination with low‐dose ritonavir) and to relate these differences to safety and efficacy. Data originated from pre‐defined pharmacokinetic substudies within two randomized 48‐week trials evaluating the safety and efficacy of three protease inhibitor regimens. At weeks 4 and 48, plasma was collected and minimum drug plasma concentrations, Cmin, were obtained. Out of 656 randomized patients, 283 patients had available Cmin at week 4. Indinavir, saquinavir and lopinavir Cmin were high when combined with low‐dose ritonavir. No significant difference in the proportion of patients experiencing treatment failure could be found according to the Cmin within any treatment arm. A saquinavir Cmin > 2000 ng/ml was associated with an increased risk of gastrointestinal grade 3 or 4 adverse events and higher total cholesterol. Overall, there were no changes in Cmin from week 4 to week 48 in patients who remained on therapy. No association between treatment failure and the Cmin could be demonstrated. Associations between high Cmin and toxicity were identified in the saquinavir arm; therefore, dose reductions may be appropriate in certain patients with Cmin several times above the minimum effective concentration.
Bursts of Potential Elicited by d‐Amphetamine in Central Snail Neuron: Effect of Sodium Azide
Authors: Lin Pei‐Lin , Lu Kuan‐Ling , Lee Ya‐Ling , Chen Yi‐Hung , Chang Yu‐Chi , Chou Hong‐Nong , Tsai Ming‐Cheng
Published: August 2007

Abstract:   Effects of sodium azide (NaN3) on spontaneously generated action potential and bursts of potential elicited by d‐amphetamine (d‐amphetamine‐elicited BoP) were studied on the right parietal 4 (RP4) neuron of the snail Achatina fulica Ferussac in vitro. Sodium azide altered the spontaneous action potential of RP4 neuron in a concentration‐dependent manner. In lower concentrations, neither NaN3 (30, 100, 300 µM; 1 and 3 mM) nor d‐amphetamine (135 µM) affect the resting membrane potential, amplitude and frequency of RP4 neurons, while in the higher concentrations NaN3 (30 mM) did abolish the spontaneous action potential on RP4 neurons and depolarized the RP4 neurons reversibly. At lower concentration, NaN3 (30 µM) facilitated the d‐amphetamine‐elicited BoP. The BoP elicited by NaN3 (30 µM) and d‐amphetamine (135 µM) were decreased following treatment with KT5720 (protein kinase A inhibitor), or intracellular injection of EGTA [ethylene glycol‐bis(2‐aminoethyl ether)‐N,N,N′,N′‐tetraacetic acid]. However, the BoP was not affected by applying U73122 (1‐[6‐[((17β)‐3‐methoxyestra‐1,3,5[10]‐trien‐17‐yl)amino]hexyl]‐1H‐pyrrole‐2,5‐dione) or neomycin (phospholipase inhibitors). Voltage clamp studies revealed that NaN3 (30 µM) did not alter the total fast inwards currents (70 msec.) and the steady‐state outwards currents (5 sec.). It appeared that the BoP elicited by NaN3 (30 µM) and d‐amphetamine (135 µM) was mainly due to protein kinase A‐related messenger system and intracellular calcium. It is concluded that d‐amphetamine‐elicited BoP was not mainly due to inhibition of the function of mitochondria in the neuron while the function of mitochondria did alter the BoP elicited by amphetamine.
μ‐Opioid Receptor Ligands Lack Receptor Subtype Selectivity in the Aequorin Luminescence‐based Calcium Assay
Authors: Fichna Jakub , Staniszewska Renata , Poels Jeroen , Broeck Jozef Vanden , Janecka Anna
Published: August 2007

The aim of the present study was to characterize the binding selectivity of the μ‐opioid receptor ligands, endomorphin‐1, endomorphin‐2, and DAMGO, in thein vitrofunctional assay, based on the changes in intracellular calcium levels. For the experiments Chinese hamster ovary cells, stably expressing human μ‐receptor, were used. The μ‐agonist‐induced calcium responses were significantly inhibited by naloxone, an opioid antagonist with high preference for the μ‐opioid receptors. Naloxonazine, a μ1‐non‐peptide antagonist, inhibited the effect of all tested μ‐agonists. However, there was no significant difference in the antagonist effect of naloxonazine on the calcium response induced by μ1‐ (endomorphin‐2) and μ2‐agonists (endomorphin‐1, DAMGO). [d‐Pro2]endomorphin‐1 and [d‐Pro2]endomorphin‐2, putative peptide μ2‐ and μ1‐antagonists, respectively, which had been shownin vivoto inhibit the antinociception induced by μ‐agonists, produced no inhibitory effect in ourin vitroexperiments. Our results demonstrated that there is only one population of the μ‐opioid receptors expressed in the Chinese hamster ovary cells. We suggest that the μ‐opioid receptors form a homogenous population in thein vitrosystems. However, the existence of μ‐receptor subtypesin vivois still pharmacologically possible.
Suppression of Type 1 Diabetes in NOD Mice by Bifunctional Peptide Inhibitor: Modulation of the Immunological Synapse Formation
Authors: Murray Joseph S. , Oney Sabah , Page Jennifer E. , Kratochvil‐Stava Angela , Hu Yongbo , Makagiansar Irwan T. , Brown John C. , Kobayashi Naoki , Siahaan Teruna J.
Published: August 2007

The aim of this work was to design and utilize a bifunctional peptide inhibitor called glutamic acid decarboxylase–bifunctional peptide inhibitor to suppress the progression of type 1 diabetes in non‐obese diabetic mice. The hypothesis is that glutamic acid decarboxylase–bifunctional peptide inhibitor binds simultaneously to major histocompatibility complex‐II and intercellular adhesion molecule type 1 on antigen‐presenting cell and inhibits the immunological synapse formation during T‐cell–antigen‐presenting cell interactions. Glutamic acid decarboxylase–bifunctional peptide inhibitor was composed of a major epitope of the type 1 diabetes‐associated antigen, glutamic acid decarboxylase 65 kDa, covalently linked to a peptide derived from CD11a of lymphocyte function‐associated antigen‐1. The suppression of insulitis and type 1 diabetes was evaluated using non‐obese diabetic and non‐obese diabetic severe combined immunodeficiency mice. Glutamic acid decarboxylase–bifunctional peptide inhibitor had the capacity to suppress invasive insulitis in non‐obese diabetic mice. CD4+ T‐cells isolated from glutamic acid decarboxylase–bifunctional peptide inhibitor treated mice also suppressed insulitis and hyperglycemia when transferred with diabetogenic non‐obese diabetic spleen cells into non‐obese diabetic severe combined immunodeficiency recipients. As predicted, the glutamic acid decarboxylase–bifunctional peptide inhibitor cross‐linked a significant fraction of major histocompatibility complex class‐II molecules to intercellular adhesion molecule type 1 molecules on the surface of live antigen‐presenting cell. Intravenous injection of the glutamic acid decarboxylase–bifunctional peptide inhibitor elicited interleukin‐4‐producing T‐cells in non‐obese diabetic mice primed against the glutamic acid decarboxylase‐epitope peptide. Together, the results indicate that glutamic acid decarboxylase–bifunctional peptide inhibitor induces interleukin‐4‐producing regulatory cells but does not expand the glutamic acid decarboxylase‐specific Th2 population. Given that Th2 effector cells can cause pathology, the glutamic acid decarboxylase–bifunctional peptide inhibitor may represent a novel mechanism to induce interleukin‐4 without Th2‐associated pathology.
Structural Model of Human PSA: A Target for Prostate Cancer Therapy
Authors: Hassan Md Imtaiyaz , Kumar Vijay , Singh Tej P. , Yadav Savita
Published: August 2007

Based on unique biology of prostate cancer, prostate‐specific antigen could be a useful target for prostate cancer therapies. Such targeting requires the identification of highly selective inhibitor‐binding sites. Three‐dimensional structure was calculated by homology modeling. The overall structure of human prostate‐specific antigen is composed of two β‐barrel domain, kallikrein loop and active‐site triad His57, Asp102, and Ser195. Structure of human prostate‐specific antigen is quite similar to hK‐1 and HPK‐3. The major differences were observed at kallikrein loop and position of active site. The substrate‐binding pocket is predominated by hydrophobic residues and the bottom of the specificity pocket contains Ser189 as in chymotrypsin, which provides substrate specificity. The hydrophobic, and preferentially aromatic (Trp215), amino acid residues are determinant of substrate binding due to the presence of hydrophobic crevice between Tyr99 and Trp215. Crystal structure of human prostate‐specific antigen is not determined till now and hence the report on an accurate and comparative model of human prostate‐specific antigen is probably to help in understanding their functional network and finally could be helpful in structure‐based rational drug designing.
Patents and Access to Antiretroviral Medicines in Vietnam after World Trade Organization Accession
Authors: Kuanpoth Jakkrit
Published: August 2007

Antiretroviral (ARV) drugs, where they are accessible, have been shown to prolong the lives and increase the health and well‐being of people living with human immunodeficiency virus/acquired immunodeficiency syndrome. In general terms, whether a country is able to provide affordable ARVs to people in need is determined by the pricing structure of the drugs, which is in turn based on the patent environment that regulates them. Increasing access in many developing countries, including Vietnam, requires a thorough understanding of the patent environment and of the legal options that will allow the production and/or importation of affordable treatments. This article provides an analysis of current patent law in Vietnam with regard to the production and importation of pharmaceuticals. It then reviews the current situation of supply of ARVs with regard to pharmaceutical patents and Vietnam's obligations and practices against international agreements. The study concludes by suggesting options for utilizing current law to improve access to ARVs and makes recommendations for the implementation of Vietnamese patent law.
Four canals in the mesial root of a mandibular first molar. A case report under the operating microscope
Authors: Kontakiotis Evangelos G. , Tzanetakis Giorgos N.
Published: August 2007

In this era of microscope‐assisted endodontics, finding variations in root canal system anatomy is not uncommon. Operating microscopes combined with careful clinical examination and radiographic interpretation can aid the clinician to successfully treat cases with such internal anatomy. The understanding of this view enables the possible location of additional canals in any tooth requiring endodontic treatment. The present clinical article demonstrates a rare anatomical complexity in the mesial root of a mandibular first molar. Four independent root canal orifices were found in this root by clinical detection with the aid of a dental operating microscope. This case shows that additional canals can be located in any root undergoing endodontic treatment and clinicians should always be aware of aberrant internal anatomy.
Treatment and evaluation of patients with acute exacerbation of asthma before and during a visit to the ER in Denmark
Authors: Backer Vibeke , Harving Henrik , Søes‐Petersen Ulrik , Ulrik Charlotte Suppli , Plaschke Peter , Lange Peter
Published: August 2007

Background:  Acute exacerbation of asthma may be life‐threatening and quite often results in a visit to the emergency room (ER) or admission to a hospital. The aim was to evaluate the treatment and the quality of clinical management of asthma exacerbations, and finally, to identify the factors leading to admission.

Material and methods:  In a retrospective design, we audited the hospital records of all patients aged 18–40 years admitted to five Danish university hospitals with an acute exacerbation of asthma in 2004.

Results:  We found records covering 323 asthmatic patients (186 women). Before admission, the mean (standard deviation) duration of the exacerbation was 5.2 (7.5) days. Of those admitted, 14% did not use any medication, 39% used inhaled corticosteroids (ICS) either with a β2‐agonist or alone, systemic steroids, and 34% used a β2‐agonist alone. Lung function (peak flow or forced expiratory volume in first second) was measured in 60% on admission, in 58% on discharge and in 47% on both occasions (P < 0.01). Temperature, heart rate and oxygen saturation were measured in 231 of the patients (72%), but the respiratory frequency rate was measured in only 16% of the patients, with some differences between the five hospitals. On discharge, 50% were treated with systemic steroids, and a further 20% had ICS prescribed (P < 0.01, admission vs discharge). In 21% of the cases, inadequate treatment was identified as the most likely reason for their ER visit/admission to a hospital.

Conclusions:  The assessment and treatment of patients admitted with acute asthma exacerbation was often suboptimal. Under‐treatment with the anti‐asthmatic medication was the main reason for admission.

Please cite this paper as: Backer V, Harving H, Søes‐Petersen U, Ulrik CS, Plaschke P and Lange P. Treatment and evaluation of patients with acute exacerbation of asthma before and during a visit to the ER in Denmark. The Clinical Respiratory Journal 2008; 2: 54–59.
Associations between Missing Teeth with Unmet Needs and Socioeconomic Status among South Korean Dentate Government Employees
Authors: Kim Hae‐Young , Lee Seung‐Wook , Cho Sung‐Il , Patton Lauren L. , Ku Young
Published: August 2007

Objective: This study aims to examine associations between missing teeth with unmet needs (MTUN) and socioeconomic status, represented by income and place of residence.

Methods: The National Health Insurance Corporation dataset of 822,325 dentate Korean government employees’ dental examinations results, questionnaire responses in the year 2000, and basic information collected for administrative purposes was used for this analysis. The main outcome variable was the number of MTUN, categorized into three groups: none, 1‐2, and ≥3. Explanatory variables were assessed and a multinomial logistic regression was employed.

Results: Seventy percent were men, with a mean age of 39.1 years (range 18 to 74). The mean number of MTUN was 0.34, and 19.1 percent had ≥1 MTUN. After adjusting for other variables, age and income were the most salient independent predictors. Rural residents, men, older adults, persons having smoking experience, and persons visiting a dental clinic in the past year were more likely to have ≥1 MTUN than their counterparts. People performing frequent toothbrushing or having received professional scaling in the past year were less likely to have ≥1 MTUN than their counterparts.

Conclusion: Among South Korean government employees with a general dental care insurance benefit, exclusive of prosthetic services, having normative unmet prosthetic need was significantly associated with older age, lower income, and rural residence, taking into account other demographic factors, personal health practices, and dental service utilization.
Atraumatic Restorative Treatment and Dental Anxiety in Outpatients Attending Public Oral Health Clinics in South Africa
Authors: Mickenautsch Steffen , Frencken Jo E. , Van’t Hof Martin A.
Published: August 2007

Objectives: This study was undertaken to test the hypotheses that using the atraumatic restorative treatment (ART) approach results in lower patient anxiety and that lower anxiety leads to higher restoration/extraction ratios.

Methods: The test group of dental operators (n=9) was trained in ART. The control group (n=11) was not, and did not apply ART. The Short Form of the Dental Subscale of the Children’s Fear Survey Schedule (CFSS‐SF) and Corah’s Dental Anxiety Scale (DAS) were used to assess patient anxiety after ART (test group) and after traditional restorations (control group). The restoration/extraction ratio calculated for primary (children) and permanent dentitions (adults) per operator was based on 12‐month treatment statistics. Dental anxiety assessments were analysed using ANOVA. Differences were compared using the t‐test and corrected for confounding factors (ANCOVA). The Pearson correlation coefficient was used to measure the correlation between dental anxiety levels and restoration/extraction ratios.

Results: The mean CFSS‐SF score for test‐group children was statistically significantly lower than for the control‐group children. The mean DAS score for test‐group adults was statistically significant lower than the control. No significant correlation was observed between dental anxiety level and restoration/extraction ratio per operator for both dentitions in both groups.

Conclusion: The first hypothesis was accepted; the second, rejected. Although dental anxiety scores were lower both in child and in adult patients treated by ART than in those who received traditional restorative treatments, this positive effect had not resulted in higher restoration/extraction ratios.
Knowledge and Use of Fluoride among Indiana Dental Professionals
Authors: Yoder K. M. , Maupome G. , Ofner S. , Swigonski N. L.
Published: August 2007

Objectives: This study assessed the knowledge of Indiana dentists and dental hygienists about fluoride's predominant mode of action and their protocols for the use of fluoride for dental caries prevention.

Methods: In 2000, questionnaires were mailed to 6,681 Indiana dentists and hygienists prior to the 2001 release of recommendations for the use of fluoride by the US Centers for Disease Control and Prevention . In 2005, the questionnaires were again sent to Indiana dental professionals to assess changes in knowledge and protocols. In addition, a 10 percent sample of Illinois dentists and hygienists were surveyed to determine the similarity of Indiana and Illinois responses.

Results: Questionnaires were anonymously completed and returned. In 2000, a minority of Indiana health professionals (17 percent) correctly identified that remineralization was fluoride's predominant mode of action. There was a significant increase in Indiana respondents correctly identifying this predominant mode of action between 2000 and 2005 (17 percent versus 25 percent, respectively, P < 0.0001). Fourteen percent of Illinois respondents answered correctly in 2005. Preeruptive incorporation of fluoride into enamel was the most frequently cited incorrect response (IN 2000, 79 percent; IN 2005, 71 percent; IL 2005, 82 percent). Some protocols for use of fluoride products reflected inadequate understanding of fluoride's predominant posteruptive mode of action.

Conclusions: The majority of dental professionals surveyed were unaware of the current understanding of fluoride's predominant posteruptive mode of action through remineralization of incipient carious lesions. Additional research is indicated to assess fluoride knowledge and protocols of dental professionals nationwide. Educational efforts are needed to promote the appropriate use of fluoride.
Dental Service Utilization among Urban and Rural Older Adults in China – A Brief Communication
Authors: Wu Bei
Published: August 2007

Objectives: China's health care system is bifurcated in nature between rural and urban areas. In addition, there is a huge gap in socioeconomic status between rural and urban residents. The purpose of the study was to examine the factors related to dental visits among elders in rural and urban areas of Shanghai, China.

Methods: Using a stratified random sampling method, a cross‐sectional, face‐to‐face survey was conducted among elders aged 60 years and above in Shanghai during 2003‐04. A total of 1,044 older respondents were included in the sample.

Results: There was a significant urban and rural difference in dental visit rates over the 12‐month period of the study. Results from the logistic regression analysis suggested that residing in urban areas was a significant positive factor related to dental visits. In addition, being younger, being able to pay out‐of‐pocket medical expenses, having had regular medical checkups, having a higher number of limitations because of chronic conditions, and being more concerned about eating a healthy diet were associated with increased odds of dental visits.

Conclusions: Results suggest that urban–rural differences, as reflected in the socioeconomic status gap, disparity in medical insurance coverage, and access to dental care, have a significant impact on the use of dental services by Chinese elders. Individual sociodemographic characteristics, health status, and health attitude are important explanatory variables.
Periodontal Disease among Adult, New‐Immigrant, Chinese Americans in Boston with and without Diabetes – A Brief Communication
Authors: Leong Peggy , Tumanyan Sona , Blicher Brooke , Yeung Albert , Joshipura Kaumudi
Published: August 2007

Objectives: We compared the periodontal disease levels in a population of low socioeconomic status (SES), urban, adult, Chinese American immigrants with and without type 2 diabetes.

Methods: Dental records of 51 diabetic adults were compared with 102 nondiabetic controls from South Cove Community Health Center, Boston, MA, cross‐matched by age and gender.

Results: Our results showed that the proportion of sites with bone loss greater than 5 mm in the mesial areas of teeth was significantly correlated with higher glycosylated hemoglobin (HbA1c) (r = 0.35, P‐value = 0.01). The number of teeth with mesial bone loss of greater than 5 mm was correlated to increasing HbA1c (r = 0.37, P‐value = 0.01).

Conclusions: Our preliminary data showed that mesial bone loss greater than 5 mm was correlated with inadequate control of diabetes. The implications and recommendations for the dental care of immigrant Chinese Americans with diabetes were discussed.
Control Design for a Bottoming Solid Oxide Fuel Cell Gas Turbine Hybrid System
Authors: Mueller Fabian , Jabbari Faryar , Brouwer Jacob , Roberts Rory , Junker Tobias , Ghezel-Ayagh Hossein
Published: August 2007

A bottoming 275kW planar solid oxide fuel cell (SOFC) gas turbine (GT) hybrid system control approach has been conceptualized and designed. Based on previously published modeling techniques, a dynamic model is developed that captures the physics sufficient for dynamic simulation of all processes that affect the system with time scales of >10ms. The dynamic model was used to make system design improvements to enable the system to operate dynamically over a wide range of power output (15–100% power). The wide range of operation was possible by burning supplementary fuel in the combustor and operating the turbine at variable speed for improved thermal management. The dynamic model was employed to design a control strategy for the system. Analyses of the relative gain array (RGA) of the system at several operating points gave insight into input/output (I/O) pairing for decentralized control. Particularly, the analyses indicate that, for SOFC/GT hybrid plants that use voltage as a controlled variable, it is beneficial to control system power by manipulating fuel cell current and to control fuel cell voltage by manipulating the anode fuel flowrate. To control the stack temperature during transient load changes, a cascade control structure is employed in which a fast inner loop that maintains the GT shaft speed receives its set point from a slower outer loop that maintains the stack temperature. Fuel can be added to the combustor to maintain the turbine inlet temperature for the lower operating power conditions. To maintain fuel utilization and to prevent fuel starvation in the fuel cell, fuel is supplied to the fuel cell proportionally to the stack current. In addition, voltage is used as an indicator of varying fuel concentrations, allowing the fuel flow to be adjusted accordingly. Using voltage as a sensor is shown to be a potential solution to making SOFC systems robust to varying fuel compositions. The simulation tool proved effective for fuel cell/GT hybrid system control system development. The resulting SOFC/GT system control approach is shown to have transient load-following capability over a wide range of power, ambient temperature, and fuel concentration variations.
A Novel Direct Carbon Fuel Cell Concept
Authors: Jain Sneh L. , Lakeman J. Barry , Pointon Kevin D. , Irvine John T. S.
Published: August 2007

This paper describes a direct carbon fuel cell (DCFC) based on a solid oxide fuel cell (SOFC) system which has been used to assess the performance of a high surface area carbon fuel material. The cell, consisting of a co-fired anode, electrolyte, and cathode, has been produced by standard tape casting methods and is of tubular geometry. The operating conditions of the cell require a 62mol%Li2CO3 and 38mol%K2CO3 eutectic secondary electrolyte and the operation of the cell is described over the temperature range 525–700°C. The cell performance has been examined by standard electrochemical methods.
Thermodynamic Analysis of Integrated Molten Carbon Fuel Cell–Gas Turbine Cycles for Sub-MW and Multi-MW Scale Power Generation
Authors: Campanari S. , Iora P. , Silva P. , Macchi E.
Published: August 2007

This paper investigates the thermodynamic potential of the integration of molten carbon fuel cell (MCFC) technology with gas turbine systems for small-scale (sub-megawatt or sub-MW) as well as large-scale (multi-MW) hybrid cycles. Following the proposals of two important MCFC manufacturers, two plant layouts are discussed, the first based on a pressurized, externally reformed MCFC and a recuperated gas turbine cycle and the second based on an atmospheric MCFC, with internal reforming integrated within an externally fired gas turbine cycle. Different levels of components quality are considered, with an analysis of the effects of variable pressure ratios, different fuel mixture compositions (variable steam-to-carbon ratio) and turbine inlet temperature levels, together with potential advantages brought about by an intercooled compression process. The analysis shows interesting effects due to the peculiarity of the mutual interactions between gas turbine cycle and fuel cells, evidencing the importance of a careful thermodynamic optimization of such cycles. Results show the possibility to achieve a net electrical efficiency of about 57–58% for a small plant size (with a difference of 1.5–2 percentage points between the two layouts), with the potential to reach a 65% net electrical efficiency when integrated in advanced cycles featuring high-efficiency, large-scale equipment (multi-MW scale cycles).
Numerical Modeling of a Single Channel Polymer Electrolyte Fuel Cell
Authors: Vasileiadis N. , Brett D. J. L. , Vesovic V. , Kucernak A. R. , Fontes E. , Brandon N. P.
Published: August 2007

A two-dimensional model of a single-channel polymer fuel cell has been developed. To achieve model validation, current mapping experiments were performed on the cathode side of a single-channel polymer electrolyte fuel cell (PEFC) of various channel widths, at different reactant flow rates and over a range of operating cell voltages. The fuel side was operated in cross-flow mode, with a high stoichiometric excess of hydrogen to ensure no limitations in anode performance as a function of position along the channel. The solution domain comprises seven regions, (two inlet channels, two diffusers, two active catalyst layers, and a membrane) and considers transport of hydrogen and water vapor in the anode and oxygen and nitrogen and water vapor in the cathode. The resulting set of coupled differential equations was solved numerically with FEMLAB®, a MATLAB®-based software. The model has been compared to data from a single-channel PEFC, and good agreement between experiment and theory was obtained.
Polymer Electrolyte Fuel Cell Stacks at CNR-ITAE: State of the Art
Authors: Squadrito G. , Barbera O. , Giacoppo G. , Urbani F. , Passalacqua E.
Published: August 2007

Fuel cell technology development is one of the main activities at CNR-TAE Institute. Particular attention was devoted to polymer electrolyte fuel cells (PEFCs), which are the most probable candidates as future energy suppliers for transportation and for portable and domestic applications. The research activity was addressed to new materials and component evolution, system design, and modeling. Because a single cell is not able to supply the desired voltages also for small electronic devices, a PEFC stack of different sizes must be evolved to match the application request. The research activity focused on two different areas: small size stacks for portable applications and medium power stacks (1–4kW) for transport and stationary applications. This activity was supported by modeling and computational fluid dynamic studies, and by the evolution of dedicated test station and measurement devices. The first result of PEFC stack research was the development of a 100W stack prototype working at low pressure and based on low Pt loading electrodes evolved at CNR-ITAE. Starting from this experience, a hydrogen fueled air breathing stack of 15W for portable application was realized. The scale up of the cell active area was approached by searching for a method to allow the design of the flow field with specified geometrical characteristics and fluid dynamic properties to maintain the performance reached in small active area cells. A computer-aided design method was evolved, and the design of the 200cm2 active area cell was realized, starting, from a 50cm2 laboratory cell.
Remembering Dick Crane
Authors: Jossem E. Leonard
Published: August 2007

Physicist, polymath, educator, leader, Horace Richard Crane died on April 19, 2007, a few months short of his 100th birthday. Those of us who were fortunate enough to have had him as a friend mourn his loss, but for all of us he leaves a rich and varied legacy of published works that invite reading and rereading.

Dick's work as a physicist was recognized in 1966 by his election to the National Academy of Sciences and in 1986 by the award of the President's National Medal of Science: “For the first measurement of the magnetic moment and spin of free electrons and positrons.”
Aerodynamics of a Party Balloon
Authors: Cross Rod
Published: August 2007

It is well-known that a party balloon can be made to fly erratically across a room, but it can also be used for quantitative measurements of other aspects of aerodynamics. Since a balloon is light and has a large surface area, even relatively weak aerodynamic forces can be readily demonstrated or measured in the classroom. Accurate measurements can be made of drag and buoyant forces, and reasonable estimates can also be made of the Magnus force on a spinning balloon.
arXiv.org and Physics Education
Authors: Ramlo Susan
Published: August 2007

The website arXiv.org (pronounced archive) is a free online resource for full-text articles in the fields of physics, mathematics, computer science, nonlinear science, and quantitative biology that has existed for about 15 years. Available directly at http://www.arXiv.org, this e-print archive is searchable. As of Jan. 3, 2007, arXiv had open access to 401,226 e-prints in the topic areas.1 Those who sign up for an ID and password can also sign up for daily submission abstract emails for specific subject classes of arXiv, including physics education, physics and society, and history of physics. Founded and developed by Paul Ginsparg when he was at Los Alamos National Laboratory, arXiv's original name was the LANL preprint archive or xxx.lanl.gov. The location and name changed after Ginsparg moved to the physics department at Cornell University. Today, arXiv is hosted and operated by Cornell University library. Mirror sites for arXiv exist worldwide.2
A Simple Classroom Simulation of Heat Energy Diffusing Through a Metal Bar
Authors: Kinsler Mark , Kinzel Evelyn
Published: August 2007

We present an iterative procedure that does not rely on calculus to model heat flow through a uniform bar of metal and thus avoids the use of the partial differential equation typically needed to describe heat diffusion. The procedure is based on first principles and can be done with students at the blackboard. It results in a plot that illustrates several principles of thermodynamics and can be easily implemented with a spreadsheet program on the computer.
Determining the Curie Temperature of Iron and Nickel
Authors: Velasco S. , Román F. L.
Published: August 2007

The phenomenon of ferromagnetism is well-known to high school and undergraduate students, and its physical basis is explained in most general physics textbooks.1–2 There are some elegant undergraduate experiments that investigate the ferromagnetic-paramagnetic phase transition by means of the analysis of the magnetic properties and the electrical resistance of the material above and below the transition point.3–6 However, most of the simple classroom demonstrations of this phenomenon are designed essentially for demonstrating the existence of the Curie point. In this paper we describe a rather simple demonstration experiment for determining quantitatively the Curie temperature of a ferromagnetic material.
Mixed Infections, Cryptic Diversity, and Vector-Borne Pathogens: Evidence from
Polygenis
Fleas and
Bartonella
Species
Authors: Abbot Patrick , Aviles Alena E. , Eller Lauren , Durden Lance A.
Published: August 2007

Coinfections within hosts present opportunities for horizontal gene transfer between strains and competitive interactions between genotypes and thus can be a critical element of the lifestyles of pathogens.
Bartonella
spp. are
Alphaproteobacteria
that parasitize mammalian erythrocytes and endothelial cells. Their vectors are thought to be various biting arthropods, such as fleas, ticks, mites, and lice, and they are commonly cited as agents of various emerging diseases. Coinfections by different
Bartonella
strains and species can be common in mammals, but little is known about specificity and coinfections in arthropod vectors. We surveyed the rate of mixed infections of
Bartonella
in flea vectors (
Polygenis gwyni
) parasitizing cotton rats (
Sigmodon hispidus
) in which previous surveys indicated high rates of infection. We found that nearly all fleas (20 of 21) harbored one or more strains of
Bartonella
, with rates of coinfection approaching 90%. A strain previously identified as common in cotton rats was also common in their fleas. However, another common strain in cotton rats was absent from
P. gwyni
, while a rare cotton rat strain was quite common in
P. gwyni
. Surprisingly, some samples were also coinfected with a strain phylogenetically related to
Bartonella clarridgeiae
, which is typically associated with felids and ruminants. Finally, a locus (
pap31
) that is characteristically borne on phage in
Bartonella
was successfully sequenced from most samples. However, sequence diversity in
pap31
was novel in the
P. gwyni
samples, relative to other
Bartonella
previously typed with
pap31
, emphasizing the likelihood of large reservoirs of cryptic diversity in natural populations of the pathogen.
Microbial Community Biofabrics in a Geothermal Mine Adit
Authors: Spear John R. , Barton Hazel A. , Robertson Charles E. , Francis Christopher A. , Pace Norman R.
Published: August 2007

Speleothems such as stalactites and stalagmites are usually considered to be mineralogical in composition and origin; however, microorganisms have been implicated in the development of some speleothems. We have identified and characterized the biological and mineralogical composition of mat-like biofabrics in two novel kinds of speleothems from a 50°C geothermal mine adit near Glenwood Springs, CO. One type of structure consists of 2- to 3-cm-long, 3- to 4-mm-wide, leather-like, hollow, soda straw stalactites. Light and electron microscopy indicated that the stalactites are composed of a mineralized biofabric with several cell morphotypes in a laminated form, with gypsum and sulfur as the dominant mineral components. A small-subunit rRNA gene phylogenetic community analysis along the stalactite length yielded a diverse gradient of organisms, with a relatively simple suite of main constituents:
Thermus
spp., crenarchaeotes,
Chloroflexi
, and
Gammaproteobacteria
. PCR analysis also detected putative crenarchaeal ammonia monooxygenase subunit A (
amoA
) genes in this community, the majority related to sequences from other geothermal systems. The second type of speleothem, dumpling-like rafts floating on a 50°C pool on the floor of the adit, showed a mat-like fabric of evidently living organisms on the outside of the dumpling, with a multimineral, amorphous, gypsum-based internal composition. These two novel types of biofabrics are examples of the complex roles that microbes can play in mineralization, weathering, and deposition processes in karst environments.
Tick-Borne Zoonotic Bacteria in Wild and Domestic Small Mammals in Northern Spain
Authors: Barandika J. F. , Hurtado A. , García-Esteban C. , Gil H. , Escudero R. , Barral M. , Jado I. , Juste R. A. , Anda P. , García-Pérez A. L.
Published: August 2007

The prevalence and diversity of tick-borne zoonotic bacteria (
Borrelia
spp.,
Anaplasma phagocytophilum
,
Coxiella burnetii
, and spotted fever group rickettsiae) infecting 253 small mammals captured in the Basque Country (Spain) were assessed using PCR and reverse line blot hybridization. Trapping sites were selected around sheep farms (study 1, 2000 to 2002) and recreational parks (study 2, 2003 to 2005). The majority of the studied mammals (162) were wood mice (
Apodemus sylvaticus
), but six other different species were also analyzed: yellow-necked mice (
Apodemus flavicollis
), shrews (
Crocidura russula
and
Sorex coronatus
), bank voles (
Clethrionomys glareolus
), domestic mice (
Mus domesticus
), and moles (
Talpa europaea
). The results showed an infection rate ranging from 10.7% to 68.8%, depending on the small mammal species. One
C. russula
shrew and one
A. sylvaticus
mouse gave positive reactions for
A. phagocytophilum
, and
C. burnetii
was detected in two domestic mice and one
A. sylvaticus
mouse in a farm. The DNA of
Borrelia
spp. was detected in 67 animals (26.5%), most of them presenting positive hybridization with the probe for
Borrelia
sp. strain R57, the new
Borrelia
species previously detected in small mammals in our region. Furthermore, a second PCR and reverse line blot hybridization specific for
B. burgdorferi
sensu lato revealed the presence of
Borrelia afzelii
in 6.3% of
C. glareolus
voles and 14.3% of
S. coronatus
shrews. All small mammals were negative for spotted fever group rickettsiae. These results highlight the relevance of small mammals as reservoirs of some zoonotic bacteria.
Use of the
tna
Operon as a New Molecular Target for
Escherichia coli
Detection
Authors: Bernasconi Camilla , Volponi Giorgio , Picozzi Claudia , Foschino Roberto
Published: August 2007

A quantitative real-time PCR targeting the
tnaA
gene was studied to detect
Escherichia coli
and distinguish
E. coli
from
Shigella
spp. These microorganisms revealed high similarity in the molecular organization of the
tna
operon.
Archaeal and Bacterial Glycerol Dialkyl Glycerol Tetraether Lipids in Hot Springs of Yellowstone National Park
Authors: Schouten Stefan , van der Meer Marcel T. J. , Hopmans Ellen C. , Rijpstra W. Irene C. , Reysenbach Anna-Louise , Ward David M. , Sinninghe Damsté Jaap S.
Published: August 2007

Glycerol dialkyl glycerol tetraethers (GDGTs) are core membrane lipids originally thought to be produced mainly by (hyper)thermophilic archaea. Environmental screening of low-temperature environments showed, however, the abundant presence of structurally diverse GDGTs from both bacterial and archaeal sources. In this study, we examined the occurrences and distribution of GDGTs in hot spring environments in Yellowstone National Park with high temperatures (47 to 83°C) and mostly neutral to alkaline pHs. GDGTs with 0 to 4 cyclopentane moieties were dominant in all samples and are likely derived from both (hyper)thermophilic
Crenarchaeota
and
Euryarchaeota
. GDGTs with 4 to 8 cyclopentane moieties, likely derived from the crenarchaeotal order
Sulfolobales
and the euryarchaeotal order
Thermoplasmatales
, are usually present in much lower abundance, consistent with the relatively high pH values of the hot springs. The relative abundances of cyclopentane-containing GDGTs did not correlate with in situ temperature and pH, suggesting that other environmental and possibly genetic factors play a role as well. Crenarchaeol, a biomarker thought to be specific for nonthermophilic group I
Crenarchaeota
, was also found in most hot springs, though in relatively low concentrations, i.e., <5% of total GDGTs. Its abundance did not correlate with temperature, as has been reported previously. Instead, the cooccurrence of relatively abundant nonisoprenoid GDGTs thought to be derived from soil bacteria suggests a predominantly allochthonous source for crenarchaeol in these hot spring environments. Finally, the distribution of bacterial branched GDGTs suggests that they may be derived from the geothermally heated soils surrounding the hot springs.
Characterization of the Polyurethanolytic Activity of Two
Alicycliphilus
sp. Strains Able To Degrade Polyurethane and
N
-Methylpyrrolidone
Authors: Oceguera-Cervantes Alejandro , Carrillo-García Agustín , López Néstor , Bolaños-Nuñez Sandra , Cruz-Gómez M. Javier , Wacher Carmen , Loza-Tavera Herminia
Published: August 2007

Two bacterial strains (BQ1 and BQ8) were isolated from decomposed soft foam. These were selected for their capacity to grow in a minimal medium (MM) supplemented with a commercial surface-coating polyurethane (PU) (Hydroform) as the carbon source (MM-PUh). Both bacterial strains were identified as
Alicycliphilus
sp. by comparative 16S rRNA gene sequence analysis. Growth in MM-PUh showed hyperbolic behavior, with BQ1 producing higher maximum growth (17.8 ± 0.6 mg·ml
−1
) than BQ8 (14.0 ± 0.6 mg·ml
−1
) after 100 h of culture. Nuclear magnetic resonance, Fourier transform infrared (IR) spectroscopy, and gas chromatography-mass spectrometry analyses of Hydroform showed that it was a polyester PU type which also contained
N
-methylpyrrolidone (NMP) as an additive.
Alicycliphilus
sp. utilizes NMP during the first stage of growth and was able to use it as the sole carbon and nitrogen source, with calculated
K

s

values of about 8 mg·ml
−1
. Enzymatic activities related to PU degradation (esterase, protease, and urease activities) were tested by using differential media and activity assays in cell-free supernatants of bacterial cultures in MM-PUh. Induction of esterase activity in inoculated MM-PUh, but not that of protease or urease activities, was observed at 12 h of culture. Esterase activity reached its maximum at 18 h and was maintained at 50% of its maximal activity until the end of the analysis (120 h). The capacity of
Alicycliphilus
sp. to degrade PU was demonstrated by changes in the PU IR spectrum and by the numerous holes produced in solid PU observed by scanning electron microscopy after bacterial culture. Changes in the PU IR spectra indicate that an esterase activity is involved in PU degradation.