bluuebunny/crossref_metadata_2025 huggingface dataset:
miR‐20a and miR‐290, multi‐faceted players with a role in tumourigenesis and senescence
Authors: Rizzo Milena , Mariani Laura , Pitto Letizia , Rainaldi Giuseppe , Simili Marcella
Published: November 2010

Expression of microRNAs changes markedly in tumours and evidence indicates that they are causatively related to tumourigenesis, behaving as tumour suppressor microRNAs or onco microRNAs; in some cases they can behave as both depending on the type of cancer. Some tumour suppressor microRNAs appear to be an integral part of the p53 and Retinoblastoma (RB) network, the main regulatory pathways controlling senescence, a major tumour suppressor mechanism. The INK4a/ARF locus which codifies for two proteins, p19ARF and p16INK4a, plays a central role in senescence by controlling both p53 and RB. Recent evidence shows that the proto‐oncogene leukaemia/lymphoma related factor, a p19ARF specific repressor, is controlled by miRNAs and that miRNAs, in particular miR‐20a and miR‐290, are causatively involved in mouse embryo fibroblasts (MEF) senescence in culture. Intriguingly, both miR‐20a, member of the oncogenic miR‐17–92 cluster, and miR‐290, belonging to the miR‐290–295 cluster, are highly expressed in embryonic stem (ES) cells. The pro‐senescence role of miR‐20a and miR‐290 in MEF is apparently in contrast with their proliferative role in tumour and ES cells. We propose that miRNAs may exert opposing functions depending on the miRNAs repertoire as well as target/s level/s present in different cellular contexts, suggesting the importance of evaluating miRNAs activity in diverse genetic settings before their therapeutic use as tumour suppressors.
Modified anchored B‐Lynch uterine compression suture for post partum bleeding with uterine atony
Authors: MARASINGHE JEEVAN P. , CONDOUS GEORGE , SENEVIRATNE HARSHALAL R. , MARASINGHE UPALI
Published: November 2010

A prospective observational study was performed to evaluate the performance of a modified uterine compression suturing technique for the management of refractory post partum hemorrhage (PPH) at two leading tertiary referral centers in Colombo, Sri Lanka. An modified anchored B‐Lynch suture was done in 17 women with PPH due to uterine atony. In 13 of the women (76%), bleeding was arrested and the uterus conserved. Four women (24%) did not respond to the anchored compression sutures, necessitating emergency post partum hysterectomy. Mean age was 31.2 years. Nine of the women (53%) were primiparous and eight (47%) parous. Mean estimated blood loss was 1994 ml (range 1200–3300 ml). This newly modified anchor B‐Lynch compression suture appeared effective in controlling about 75% of PPH due to uterine atony, which allowed uterine conservation. This simple modification can provide a first line surgical step to control PPH.
Local interactions drive size dependent space competition between coral and crustose coralline algae
Authors: Buenau Kate E. , Price Nichole N. , Nisbet Roger M.
Published: November 2010

For many species, the outcome of competition for space in homogeneous habitats depends upon relative rates of growth and overgrowth. Size dependence in competition occurs when this balance shifts due to the growth of one or both species. For example, the ability of coral to compete with certain species of crustose coralline algae (CCA) may depend on whether coral colonies are large enough to avoid being overgrown. Spatially implicit models suggest size refuges from competition can improve the persistence of species with a vulnerable life stage. We use spatially explicit simulation models to explore size dependence in competition between coral and competitively dominant CCA in well lit habitat. We determine what conditions allow coral to use size refuges and whether refuges improve the recovery of coral after disturbance. Local interactions in explicit space prevent the maturation of coral into size refuges unless coral grows more rapidly than CCA or coral colonies are allowed to fuse, and mortality mechanisms can limit long‐term persistence even if the refuge is achieved. We contrast results with analogous differential equation models, with and without an explicit maturation delay, to demonstrate how the predicted outcome of competition is frequently reversed when local interactions and individual‐based dynamics are included in models of size‐dependent competition.
PREVALENCE AND TYPING OF LISTERIA MONOCYTOGENES STRAINS IN RETAIL VACUUM‐PACKED COLD‐SMOKED SALMON IN THE REPUBLIC OF IRELAND
Authors: DASS SAPNA CHITLAPILLY , CUMMINS ENDA J. , ABU‐GHANNAM NISSREEN
Published: November 2010

The prevalence of Listeria monocytogenes in five brands (A, B, C, D and E) of vacuum‐packed pre‐sliced cold‐smoked salmon (n = 120) marketed in different retail outlets in the Republic of Ireland was investigated. The prevalence of L. monocytogenes in the cold‐smoked salmon was 21.6%. The L. monocytogenes strains isolated from the prevalence studies were typed by using Multi‐Locus Variable number tandem repeat Analysis; this method confirmed the type division among the L. monocytogenes isolates. A minimum spanning tree showed that isolates from brand A clustered together. Few isolates from brand B, C, D and E showed genetic similarities, while others were spread throughout the cladogram. The genetic distinction among subtypes may be processor‐specific, while the similarities among the subtypes support the hypothesis of well‐adapted clones of L. monocytogenes in the fish industry. The results highlight the need for food safety control at both pre‐processing and processing stages, as there is no bactericidal process involved to eliminate any pathogen during the processing of cold‐smoked salmon.

PRACTICAL APPLICATIONS

This study highlights the use of the Multi‐Locus Variable number tandem repeat Analysis (MLVA) strategy for subtyping L. monocytogenes strains. Genomic profiles of 61 L. monocytogenes strains were compared following isolation as part of a prevalence study for vacuum‐packed cold‐smoked salmon in Ireland. From a food safety perspective, it is important to integrate the population genetics, evolutionary and epidemiological characteristics to trace the origin and spread of bacterial disease. MLVA is a polymerase chain reaction‐based method that uses the genetic relationship amongst the isolates, thus population and evolutionary characteristics can be inferred. Based on the MLVA analysis, the results highlighted the grouping of the isolates, which were genetically similar. The study points the importance of pre‐processing and processing safety control management from a risk minimization perspective. In addition to distinguishing subtypes, MLVA has the added advantage of being relatively faster and cheaper when compared to other subtyping methods.
EFFICACY OF SLIGHTLY ACIDIC ELECTROLYZED WATER (SAEW) FOR REDUCING MICROBIAL CONTAMINATION ON FRESH‐CUT CILANTRO
Authors: HAO JIANXIONG , LIU HAIJIE , LIU RUI , DALAI WUYUN , ZHAO RUIPING , CHEN TIANPENG , LI LITE
Published: November 2010

The efficacy of slightly acidic electrolyzed water (SAEW) for reducing microbial contamination on fresh‐cut cilantro was investigated in this study. The impacts of SAEW on the microbes of cilantro samples inoculated with two kinds of bacteria (Escherichia coli O78 and Bacillus subtilis 1.1849) were evaluated in comparison with NaClO solution and acidic electrolyzed water (AEW). Dipping with AEW, SAEW and NaClO solutions for 5 min resulted in a reduction in populations of E. coli O78 from 6.38 to 4.93, 3.89 and 4.88 log10 cfu/g and in populations of B. subtilis from 6.52 to 5.02, 4.98, 4.63 log10 cfu/g, respectively, The similar results were found that the populations on cilantro inoculated the mixture of two microbes of E. coli O78 treated with AEW, SAEW and NaClO solutions decreased to 4.15, 3.99, 5.10 log10 cfu/g, respectively, and the populations of B. subtili on cilantro decreased to 5.08,4.97,4.82 log10 cfu/g, respectively. The efficacies of SAEW wash in reducing natural micro flora on fresh‐cut cilantro were studied. The results showed SAEW had strong disinfection ability to reduce the microbe population of fresh‐cut cilantro and could be an alternative of AEW and NaClO solutions.

PRACTICAL APPLICATIONS

There has been an increasing demand for fresh‐cut vegetables in recent years. However, fresh‐cut products are susceptible to the foodborne pathogens, which result in the shortness of the shelf life and threaten the people's health. Many methods have been developed to reduce the microbial contamination on fresh‐cut cilantro such as chlorinated water rinsing, ionizing radiation, ozone water wash, acidic electrolyzed water (AEW) and so on. In an attempt to find a better method to replace AEW and NaClO solutions, efficacy of slightly acidic electrolyzed water (SAEW) for reducing microbial contamination on fresh‐cut cilantro was investigated in this study, The results showed SAEW had strong disinfection ability to reduce the microbe population of fresh‐cut cilantro and could be an alternative of AEW and NaClO solutions in practical applications.
THERMAL SANITIZING IN A COMMERCIAL DISHWASHING MACHINE
Authors: NICOLELLA CRISTIANO , CASINI BEATRICE , ROSSI FRANCESCO , CHERICONI ALESSIO , PARDINI GIANLUCA
Published: November 2010

This paper presents an experimental investigation on the thermal sanitization of food contact surfaces in a pilot dishwashing machine. The reduction of counts for Escherichia coli inoculated on clean glass surfaces was assayed in several tests performed under different conditions of temperature and duration of the washing cycles. The main aim of the measurements was to establish the relationship between operating conditions and sanitizing performance. The experimental results show that reduction of microbial counts clearly increases with the volume of water used for rinsing. On the other hand, the effect of the rinsing water temperature is less remarkable. It is inferred from these results that the reduction of microbial counts on food contact surfaces is mainly due to the mechanical elution of water jets rather than to thermal inactivation. The experimental results are analyzed using available kinetic data for reference organisms. The kinetic analysis confirms that the thermal effect is not sufficient to obtain a significant reduction of microbial counts on food contact surfaces under typical conditions of temperature and washing cycle length.

PRACTICAL IMPLICATIONS

Unsanitized food contact surfaces can be a direct or indirect source of foodborne illness, as pathogens can be transferred to food from crockery and utensils that are not properly sanitized. Improper cleaning and sanitizing of food contact surfaces is the factor most commonly related to the occurrence of foodborne illness risk in hospital, schools and restaurants. In this work, the effect of the operating conditions on the inactivation of reference microorganism (Escherichia coli) was experimentally investigated in a dishwashing machine. The experimental results on the logarithmic reduction on food contact surfaces under different conditions of temperature and contact time show that the microbial reduction in the washing machine is mainly due to the mechanical effect of elution of water jets rather than temperature. The results of this investigation can be used to determine the optimal operating conditions for the washing machine, resulting in the minimum requirement of energy and water.
CHARACTERISTICS OF BIOFILM FORMATION BY SELECTED FOODBORNE PATHOGENS
Authors: XU HUA , LEE HYEON‐YONG , AHN JUHEE
Published: November 2010

Strains of Listeria monocytogenes, Serratia liquefaciens, Shigella boydii, Staphylococcus aureus, Salmonella Enteritidis, and Bacillus cereus were used to evaluate bacterial biofilm‐forming ability in trypticase soy broth (TSB; pH 6 and pH 7) at 37C. The biofilm development was determined by using the crystal violet method and the degree of biofilm formation was expressed as the specific biofilm formation (SBF) index. Among all strains tested, L. monocytogenes and S. liquefaciens formed strong biofilms in half‐strength TSB (pH 6), showing 2.79 and 3.85 of SBF indices, respectively. The numbers of adhered L. monocytogenes and S. liquefaciens increased to 7.57 and 7.91 cfu/slide, respectively, after 36 h. The increase in the biofilm formation of L. monocytogenes and S. liquefaciens was shown in the scanning electron microscopy micrographs. The protein profile differences were observed between biofilms and planktonic cells, suggesting that biofilm‐specific protein expression is involved in the biofilm development.

PRACTICAL APPLICATIONS

Since the biofilm formation has been a major concern to the food processors and medical devices, it is worthwhile to characterize the biofilm formation of foodborne pathogens under food processing‐related stress conditions. The results suggest that foodborne pathogens have distinctive patterns of biofilm formation. Therefore, it might be useful information to better understand the mechanism of biofilm formation in different environmental conditions and evaluate the infectivity and pathogenicity of biofilm‐forming foodborne pathogens.
MICROBIOLOGICAL QUALITY AND PHENOTYPIC CHARACTERIZATION OF MICROORGANISMS ISOLATED FROM ENTERAL FEEDING, FOOD HANDLERS AND ENVIRONMENTS OF TWO PUBLIC BRAZILIAN HOSPITALS
Authors: BORGES LIANA JAYME , CAMPOS MARIA RAQUEL HIDALGO , ANDRÉ MARIA CLÁUDIA DANTAS PORFÍRIO BORGES , SERAFINI ÁLVARO BISOL
Published: November 2010

This work aimed to evaluate the microbiological conditions of enteral feeding, water, powder module and personnel samples obtained from two public hospitals in Goiânia/GO, Brazil. The Escherichia coli and Staphylococcus aureus strains isolated were submitted to antibiogram for phenotypic characterization. The S. aureus strains isolated were grouped into six phenotypic profiles (A–F). There was no correlation among strains isolated from diet and handlers samples. The E. coli strains were grouped into four phenotypic profiles (A–D). The E. coli phenotypes A and C showed the same susceptibility profile for microorganisms isolated from handlers and diets, suggesting a relationship among those isolates. Seven S. aureus and 12 E. coli isolates were resistant to two or more antibiotics. The diets presented unsatisfactory sanitary‐hygienic conditions in the hospitals evaluated because 47 samples (58.8%) from the first hospital and 30 samples (37.5%) from the second hospital were above the limits established by Brazilian legislation.

PRACTICAL APPLICATIONS

Enteral nutrition is a very important mechanism to provide support to health‐compromised patients, so the microbiological quality of this product is essential to guarantee its safety. This study emphasizes the importance of monitoring the enteral diet microbiological quality and the factors associated with its contamination. The study highlights the use of antibiogram as an instrument to correlate strains in order to help the identification of the probable origin of final product contamination.
Nutritional management of patients undergoing major upper gastrointestinal surgery: A survey of current practice in Australia
Authors: CAREY Sharon , HE Ling , FERRIE Suzie
Published: November 2010

Aim:  The aim of the present study was to survey current nutrition practice in Australian hospitals for the management of patients undergoing major upper gastrointestinal surgery, and to compare this with best practice, as it currently appears in the literature.

Methods:  A literature review was conducted to obtain current recommendations for the nutritional management of patients undergoing major upper gastrointestinal surgery. A survey was constructed to investigate whether these recommendations are being followed. Dietitians from tertiary‐referral public and private hospitals across Australia were contacted by telephone and invited to respond to the survey questions.

Results:  Forty‐two hospitals were contacted and 34 dietitians responded to the survey questions. Sixty‐three percent of dietitians reported minimal or no preoperative assessment of surgical patients, but 50% stated that they recommended immunonutrition when they did have preoperative contact, the majority following established dosage recommendations. Postoperative enteral nutrition support is not standard practice, being used routinely in only 30% of hospitals surveyed. Nutrition is usually recommenced on postoperative day 2 or 3. Post‐discharge follow up was provided by 35% of dietitians surveyed.

Conclusion:  Current recommendations in all aspects of nutrition are not being followed and there is great scope for improvement in managing patients undergoing major gastrointestinal surgery. Best practice guidelines and a shift in service provision to include better outpatient support for such a patient group is required.
How do dietitians treat symptoms of gastro‐oesophageal reflux disease in adults?
Authors: NOWAK Madeleine , BÜTTNER Petra , HARRISON Simone , MCCUTCHAN Cynthia
Published: November 2010

Aim:  The aim of the present study was to examine dietitians' use of lifestyle measures in the management of symptoms of gastro‐oesophageal reflux disease (reflux).

Methods:  Questionnaire data were collected by mail from dietitians on the 2001 register of Australian Accredited Practicing Dietitians (dietitians) via the Dietitians Association of Australia mailing system. Bivariate statistical tests were used to assess relationships.

Results:  The response rate was 65.8% (n = 798) with 699 working in positions where they consulted patients. Of those, 56.7% did not usually see patients who presented specifically for reflux, while 30.6% saw 1–2 such patients and 12.4% saw ≥3 such patients/month. Many dietitians who conducted patient consultations saw ≥1 per month who mentioned reflux during a consultation for another condition, with 24.3% seeing >5/month. These dietitians made the following lifestyle recommendations to reduce reflux symptoms: reduce weight if overweight (92.87%), avoid eating before lying down (94.8%), elevate the head of the bed (78.6%), avoid alcohol (73.7%), avoid spicy food (77.3%) and eat a diet low in fat (79.7%). Additionally, 60.5% made further recommendations ranging from avoiding large meals, caffeine, smoking, carbonated beverages and known precipitants, to increasing protein intake and considering food sensitivity. The number of lifestyle changes that the participants recommended to their patients with reflux was positively related to the number of changes they considered effective in reducing reflux symptoms (r = 0.56; P < 0.001; n = 651).

Conclusion:  The majority of dietitians recommended lifestyle modifications as treatment for reflux symptoms despite the current lack of evidence. A thorough investigation of the efficacy of this treatment appears warranted.
QSAR Analysis for Some Diaryl‐substituted Pyrazoles as CCR2 Inhibitors by GA‐Stepwise MLR
Authors: Saghaie Lotfollah , Shahlaei Mohsen , Fassihi Afshin , Madadkar‐Sobhani Armin , Gholivand Mohammad B. , Pourhossein Alireza
Published: November 2010

Quantitative relationships between calculated molecular structure and 26 diaryl‐substituted pyrazoles CCR2 inhibitors were investigated by GA‐stepwise multiple linear regression. In multiple linear regression analysis, the quantitative structure–activity relationship models were constructed by grouping descriptors and also dual selection of variables using genetic algorithm and stepwise selection methods from each group of the pool of all calculated descriptors. The accuracy of the proposed multiple linear regression model was demonstrated using the following evaluation techniques: cross‐validation, validation through an external test set, and Y‐randomization. Furthermore, the domain of applicability that shows the area of reliable predictions was defined. The prediction results were in good agreement with the experimental values.
Respiratory health effects of volcanic ash with special reference to Iceland. A review
Authors: Gudmundsson Gunnar
Published: November 2010

Background and Aims:  Volcano eruptions occur around the world and can have an impact on health in many ways both locally and on a global scale as a result of airborne dispersion of gases and ash or as impact on climate. In this review, a recent volcanic eruption in Eyjafjallajökull in Iceland is described and its effects on aviation around the globe and on respiratory health in those exposed to the volcanic ash in Iceland. Also, the effects of a large volcano eruption in Iceland in 1789 are described that also had effect on a global scale by causing air pollution.

Methods and Results:  The available studies reviewed here suggest that the acute and chronic health effects of volcanic ash depend on particle size (how much respirable), mineralogical composition (crystalline silica content) and the physico‐chemical properties of the surfaces of ash particles. These can vary between volcanoes and even between eruptions, making comparison difficult. Acute respiratory symptoms suggesting asthma and bronchitis have been well described. Exacerbations of pre‐existing lung and heart disease are common after inhalation of volcanic ash. Limited information is available on increase in mortality from recent eruptions but historical evidence is well described. No long‐term effects on lung function have been found after exposure to volcanic ash. There are concerns for the long‐term risks of silicosis from chronic exposure to volcanic ash but no cases have been described.

Conclusion:  Acute respiratory symptoms after exposure to volcanic ash are well described but no long‐term effects have been found.

Please cite this paper as: Gudmundsson G. Respiratory health effects of volcanic ash with special reference to Iceland. A review. Clin Respir J 2011; 5: 2–9.
Switching from Brand‐Name to Generic Psychotropic Medications: A Literature Review
Authors: Desmarais Julie Eve , Beauclair Linda , Margolese Howard C.
Published: November 2010

Generic medications do not undergo the rigorous approval process required of original medications. Their effectiveness and safety is expected to be equal to that of their more expensive counterparts. However, several case reports and studies describe clinical deterioration and decreased tolerability with generic substitution. Pubmed was searched from January 1, 1974 to March 1, 2010. The MeSH term “generic, drugs” was combined with “anticonvulsants,”“mood stabilizers,”“lithium,”“antidepressants,”“antipsychotics,”“anxiolytics,” and “benzodiazepines.” Additional articles were obtained by searching the bibliographies of relevant references. Articles in English, French, or Spanish were considered if they discussed clinical equivalence of generic and brand‐name medications, generic substitution, or issues about effectiveness, tolerability, compliance, or economics encountered with generics. Clinical deterioration, adverse effects, and changes in pharmacokinetics are described with generic substitution of several anticonvulsants/mood stabilizers (carbamazepine, valproate, lamotrigine, gabapentin, topiramate, lithium), antidepressants (amitriptyline, nortriptyline, desipramine, fluoxetine, paroxetine, citalopram, sertraline, venlafaxine, mirtazapine, bupropion), antipsychotics (risperidone, clozapine), and anxiolytics (clonazepam, alprazolam). Generics do not always lead to the anticipated monetary savings and also raise compliance issues. Although the review is limited by publication bias and heterogeneity of the studies in the literature, we believe there is enough concern to advise generic switching on an individual basis with close monitoring throughout the transition. Health professionals should be aware of the stakes around generic substitution especially when health economics promote universal use of generics.
Reactive Nationalism and South Korea's Foreign Policy on China and Japan: A Comparative Analysis
Authors: Moon Chung‐in , Li Chun‐fu
Published: November 2010

The advent of post‐Cold War order, growing economic interdependence and dense social and cultural networks have greatly facilitated South Korea's bilateral ties with China and Japan since the early 1990s; however, disputes over the history and territory have recently strained such ties. Whereas Japan's renewed territorial claim over Dokdo Island, its distortion of history textbooks and Koizumi's tribute to the Yasukuni Shrine dealt a critical blow to Seoul–Tokyo relations, China's Northeast Project, which claims Korea's ancient kingdom of Goguryeo as a Chinese peripheral local government, provoked widespread anti‐Chinese sentiments in South Korea. Nevertheless, South Korea's nationalist responses were not uniform. Seoul responded to Tokyo in a much tougher manner with profound diplomatic implications, whereas public outcry over China did not escalate into any specific retaliatory actions. This article argues that such variation can be explained by the dynamic interplay of issue–character, domestic political terrain involving public opinion and leadership perception and feedback from political leadership in China and Japan.
On the measurement of circulating antioxidant capacity and the nightmare of uric acid
Authors: Costantini David
Published: November 2010

1. In recent years, evolutionary ecologists have become increasingly interested in antioxidants and oxidative stress. Information on redox systems can provide new insights into our understanding of life‐history variation and animal responses to environmental stressors.

2. A common approach of ecological studies to the study of antioxidant capacity of animals has been measurement of the total antioxidant capacity of serum or plasma. Some of these studies have suggested that most of the antioxidant capacity measured in plasma is made up of uric acid and, therefore, estimates of antioxidant capacity should be corrected for the concentration of uric acid.

3. Here, I show that (i) the correlation between plasma concentration of uric acid and plasma antioxidant capacity is method dependent and (ii) different assays for the quantification of circulating antioxidant capacity can provide information on different components of the antioxidant machinery.

4. To determine whether measurements of antioxidant capacity need to be corrected for the uric acid concentration in the sample, it is therefore important to take into account the biochemical properties of the assay used.
Cholinergic modulation amplifies the intrinsic oscillatory properties of CA1 hippocampal cholecystokinin‐positive interneurons
Authors: Cea‐del Rio Christian A. , Lawrence J. Josh , Erdelyi Ferenc , Szabo Gabor , McBain Chris J.
Published: November 2010

Non‐technical summary

In the mammalian hippocampus, the neurotransmitter acetylcholine (ACh) promotes learning and memory storage. During sensory processing and learning, large ACh‐dependent electrical oscillatory events are observed, which involve the synchronization of both inhibitory and excitatory neural circuits. While the actions of ACh are known on excitatory hippocampal circuits, its actions on specific inhibitory circuits are poorly understood. We show that two types of cholecystokinin‐positive local circuit inhibitory interneuron, the so‐called ‘basket cells’ and ‘Schaffer collateral‐associated’ cells, which innervate separately the cell body and dendritic regions of principal cells, are modulated similarly by cholinergic receptor activation. In both cell types activation of their muscarinic receptors triggers a general increase of excitability and intrinsic oscillatory activity, and a more efficient engagement to slow network oscillations. Knowledge of how cholinergic neuromodulation acts on neurochemically identical but morphologically distinct inhibitory interneurons will allow us to understand the role played by this important neuromodulator during hippocampal‐dependent tasks in vivo.
Residues R282 and D341 act as electrostatic gates in the proton‐dependent oligopeptide transporter PepT1
Authors: Bossi Elena , Renna Maria Daniela , Sangaletti Rachele , D’Antoni Francesca , Cherubino Francesca , Kottra Gabor , Peres Antonio
Published: November 2010

Non‐technical summary

The oligopeptide transporter PepT1 is a protein found in the membrane of the cells of the intestinal walls, and represents the main route through which proteic nutrients are absorbed by the organism. Along the polypeptidic chain of this protein, two oppositely charged amino acids, an arginine in position 282 and an aspartate in position 341 of the sequence, have been hypothesised to form a barrier in the absorption pathway. In this paper we show that appropriate mutations of these amino acids change the properties of PepT1 in a way that confirms that these parts of the protein indeed act as an electrostatic gate in the transport process. The identification of the structural basis of the functional mechanism of this transporter is important because, in addition to its role in nutrient uptake, PepT1 represents a major pathway for the absorption of several therapeutic drugs.
Implementing Thermal Management Modeling Into SOFC System Level Design
Authors: Kattke K. J. , Braun R. J.
Published: November 2010

Effective thermal management is critical to the successful design of small (<10 kW) solid oxide fuel cell (SOFC) power systems. While separate unit processes occur within each component of the system, external heat transport from/to components must be optimally managed and taken into account in system-level design. In this paper, we present a modeling approach that captures thermal interactions among hot zone components and couples this information with system process design. The resulting thermal model is then applied to a mobile SOFC power system concept in the 1–2 kW range to enable a better understanding of how component heat loss affects process gas temperature and flow requirements throughout the flowsheet. The thermal performance of the system is examined for various thermal management strategies that involve altering the convective and radiative heat transfer in the enclosure. The impact of these measures on internal temperature distributions within the cell-stack is also presented. A comparison with the results from traditional adiabatic, zero-dimensional thermodynamic system modeling reveals that oxidant flow requirements can be overpredicted by as much as 204%, resulting in oversizing of recuperator heat duty by 221%, and that important design constraints, such as the magnitude of the maximum cell temperature gradient within the stack, are underpredicted by over 24%.
MGT/HTFC Hybrid System Emulator Test Rig: Experimental Investigation on the Anodic Recirculation System
Authors: Ferrari Mario L. , Pascenti Matteo , Magistri Loredana , Massardo Aristide F.
Published: November 2010

The Thermochemical Power Group (TPG) of the University of Genoa designed and installed a complete hybrid system emulator test rig equipped with a 100 kW recuperated micro gas turbine, a modular cathodic vessel located between recuperator outlet and combustor inlet, and an anodic recirculation system based on the coupling of a single stage ejector with an anodic vessel. The layout of the system was carefully designed, considering the coupling between a planar SOFC stack and the 100 kW commercial machine installed at TPG laboratory. A particular pressurized hybrid system was studied to define the anodic side properties in terms of mass flow rates, pressures, and temperatures. In this work, this experimental facility is used to analyze the anodic ejector performance from fluid dynamic and thermal points of view. The attention is mainly focused on the recirculation factor value in steady-state conditions. For this reason, a wide experimental campaign was carried out to measure the behavior of this property in different operative conditions with the objective to avoid carbon deposition in the anodic circuit, in the reformer, and in the fuel cell stack.
Modification of Results From Computational-Fluid-Dynamics Simulations of Single-Cell Solid-Oxide Fuel Cells to Estimate Multicell Stack Performance
Authors: Sembler William J. , Kumar Sunil
Published: November 2010

A typical single-cell fuel cell is capable of producing less than 1 V of direct current. Therefore, to produce the voltages required in most industrial applications, many individual fuel cells must typically be stacked together and connected electrically in series. Computational fluid dynamics (CFD) can be helpful to predict fuel-cell performance before a cell is actually built and tested. However, to perform a CFD simulation using a three-dimensional model of an entire fuel-cell stack can require a considerable amount of time and multiprocessor computing capability that may not be available to the designer. To eliminate the need to model an entire multicell assembly, a study was conducted to determine the incremental effect on fuel-cell performance of adding individual solid-oxide fuel cells (SOFCs) to a CFD model of a multicell stack. As part of this process, a series of simulations was conducted to establish a CFD-nodal density that would not only produce reasonably accurate results but could also be used to create and analyze the relatively large models of the multicell stacks. Full three-dimensional CFD models were then created of a single-cell SOFC and of SOFC stacks containing two, three, four, five, and six cells. Values of the voltages produced when operating with various current densities, together with temperature distributions, were generated for each of these CFD models. By comparing the results from each of the simulations, adjustment factors were developed to permit single-cell CFD results to be modified to estimate the performance of stacks containing multiple fuel cells. The use of these factors could enable fuel-cell designers to predict multicell stack performance using a CFD model of only a single cell.
Kinematics Analysis of Some Linear Legs With Different Structures for Limited-DOF Parallel Manipulators
Authors: Lu Yi , Hu Bo , Han Jianda , Yu Jianping
Published: November 2010

To solve the velocity and acceleration of legs with different structures is a fundamental and challenging issue for dynamics analysis of parallel manipulators (PMs). In this paper, the kinematics of linear legs with different structures for limited-degree of freedom (DOF) PMs is studied. First, based on kinematics/statics of general limited-DOF PM, the formulas are derived for solving the angular velocity/acceleration of some linear legs with different structures. Second, the velocity and acceleration of the piston/cylinder in the legs are represented by velocity and acceleration of platform in PM. Finally, the solving procedures are illustrated by applying this approach to a 4DOF PM.
Simulation of Edge Cracks Using Pulsed Eddy Current Stimulated Thermography
Authors: Yang Suixian , Tian Gui Yun , Abidin Ilham Zainal , Wilson John
Published: November 2010

Thermography has proven to be one of the most effective approaches to detect cracks in conductive specimens over a relatively large area. Pulsed eddy current stimulated thermography is an emerging integrative nondestructive approach for the detection and characterization of surface and subsurface cracks. In this paper, heating behaviors of edge cracks, excited by pulsed eddy currents, are examined using numerical simulations. The simulations are performed using COMSOL multiphysics finite element method simulation software using the AC/DC module. The simulation results show that in the early heating stage, the temperature increases more quickly at the crack tip compared with other points on the sample. The results indicate that to maximize sensitivity, the response should be analyzed in the early stages of the heating period, no more than 100 ms for samples in which we are interested. The eddy current density distribution is changed with a variation in inductor orientation, but the crack tips remain the “hottest” points during the excitation period, which can be used for robust quantitative defect evaluation. Signal feature selection, transient temperature profile of the sample, and influence of the inductor orientation on the detection sensitivity for edge cracks are investigated. The work shows that positioning of the inductor, perpendicular to the crack line, results in the highest sensitivity for defect detection and characterization. The crack orientation can be estimated through the rotation of the linear inductor near the sample edge and the crack tips.
Probabilistic Life Assessment of Gas Turbine Blades
Authors: Thakur Nikita , Keane A. J. , Nair P. B. , Rao A. R.
Published: November 2010

This paper addresses the problem of analyzing measurement data to estimate the variations in turbine blade life in the presence of manufacturing variability. A methodology that employs existing denoising techniques, namely, Principal Component Analysis and Fast Fourier Transform analysis, is proposed for filtering measurement error from the measured data set. An approach for dimensionality reduction is employed that uses prior knowledge on the measurement error obtained from analyzing repeated measurements. The proposed methodology also helps in capturing the effects of manufacturing drift with time and the blade to blade manufacturing error. The filtered data is then used for generating three-dimensional representations of probable manufactured blade shapes from the limited number of available measurements. This is accomplished by using a Free-Form Deformation based approach for deforming a nominal mesh to the desired shapes. Estimations of life on the probable turbine blade shapes manufactured over a span of 1 year indicate a reduction of around 1.7% in the mean life relative to the nominal life, with a maximum relative reduction of around 3.7%, due to the effects of manufacturing variability.
Singularity Analysis of Large Workspace 3RRRS Parallel Mechanism Using Line Geometry and Linear Complex Approximation
Authors: Wolf Alon , Glozman Daniel
Published: November 2010

During the last 15 years, parallel mechanisms (robots) have become more and more popular among the robotics and mechanism community. Research done in this field revealed the significant advantage of these mechanisms for several specific tasks, such as those that require high rigidity, low inertia of the mechanism, and/or high accuracy. Consequently, parallel mechanisms have been widely investigated in the last few years. There are tens of proposed structures for parallel mechanisms, with some capable of six degrees of freedom and some less (normally three degrees of freedom). One of the major drawbacks of parallel mechanisms is their relatively limited workspace and their behavior near or at singular configurations. In this paper, we analyze the kinematics of a new architecture for a six degrees of freedom parallel mechanism composed of three identical kinematic limbs: revolute-revolute-revolute-spherical. We solve the inverse and show the forward kinematics of the mechanism and then use the screw theory to develop the Jacobian matrix of the manipulator. We demonstrate how to use screw and line geometry tools for the singularity analysis of the mechanism. Both Jacobian matrices developed by using screw theory and static equilibrium equations are similar. Forward and inverse kinematic solutions are given and solved, and the singularity map of the mechanism was generated. We then demonstrate and analyze three representative singular configurations of the mechanism. Finally, we generate the singularity-free workspace of the mechanism.
Metallic Foil-Assisted Laser Cell Printing
Authors: Lin Yafu , Huang Yong , Chrisey Douglas B.
Published: November 2010

Laser direct-write technology such as modified laser-induced forward transfer (LIFT) is emerging as a revolutionary technology for biological construct fabrication. While many modified LIFT-based cell direct writing successes have been achieved, possible process-induced cell injury and death is still a big hurdle for modified LIFT-based cell direct writing to be a viable technology. The objective of this study is to propose metallic foil-assisted LIFT using a four-layer structure to achieve better droplet size control and increase cell viability in direct writing of human colon cancer cells (HT-29). The proposed four layers include a quartz disk, a sacrificial and adhesive layer, a metallic foil, and a cell suspension layer. The bubble formation-induced stress wave is responsible for droplet formation. It is found that the proposed metallic foil-assisted LIFT approach is an effective cell direct-write technology and provides better printing resolution and high post-transfer cell viability when compared with other conventional modified LIFT technologies such as matrix-assisted pulsed-laser evaporation direct-write; at the same time, the possible contamination from the laser energy absorbing material is minimized using a metallic foil.
Intrasac Pressure Changes and Vascular Remodeling After Endovascular Repair of Abdominal Aortic Aneurysms: Review and Biomechanical Model Simulation
Authors: Kwon S. T. , Rectenwald J. E. , Baek S.
Published: November 2010

In this paper, we review existing clinical research data on post-endovascular repair (EVAR) intrasac pressure and relation with abdominal aortic aneurysm (AAA) size changes. Based on the review, we hypothesize that intrasac pressure has a significant impact on post-EVAR AAA size changes, and post-EVAR remodeling depends also on how the pressure has changed over a period of time. The previously developed model of an AAA based on a constrained mixture approach is extended to include vascular adaptation after EVAR using an idealized geometry. Computational simulation shows that the same mechanism of collagen stress-mediated remodeling in AAA expansion induces the aneurysm wall to shrink in a reduced sac-pressure after post-EVAR. Computational simulation suggests that the intrasac pressure of 60 mm Hg is a critical value. At this value, the AAA remains stable, while values above cause the AAA to expand and values below cause the AAA to shrink. There are, however, variations between individuals due to different cellular sensitivities in stress-mediated adaptation. Computer simulation also indicates that an initial decrease in intrasac pressure helps the AAA shrink even if the pressure increases after some time. The presented study suggests that biomechanics has a major effect on initial adaptation after EVAR and also illustrates the utility of a computational model of vascular growth and remodeling in predicting diameter changes during the progression and after the treatment of AAAs.
Characterizations of nanoembossed Pb(Zr0.3,Ti0.7)O3 ferroelectric films
Authors: Shen Zhenkui , Chen Zhihui , Lu Qian , Jiang Anquan , Qiu Zhijun , Qu Xinping , Chen Yifang , Liu Ran
Published: November 2010

Ferroelectric thin films may find potential applications in a broad range of ferroelectronic devices such as mass-storage memories. In this article, arrays of Pb(Zr0.3,Ti0.7)O3 (PZT) ferroelectric cells with minimum lateral size down to 500 nm were fabricated by nanoembossing technique. Structural characterizations of embossed PZT film were carried out by Raman spectroscopy and x-ray diffraction. Ferroelectronic properties of embossed PZT film were investigated by using piezoresponse force microscopy and Radiant Technologies precision material analyzer. Excellent ferroelectric and piezoelectric characteristics observed in the embossed PZT films suggest that the nanoembossing process proposed in this article is promising to become a new manufacturing approach for high density PZT based memory devices at significantly lower cost than the existing technique.
Assessment of release properties in UV nanoimprint lithography using high-aspect-ratio nanoscale molds
Authors: Takahashi Junki , Taniguchi Jun , Kamiya Yasuhiro
Published: November 2010

Ultraviolet nanoimprint lithography (UV-NIL) is a potentially powerful tool for nanofabrication. However, the strong force required during the release step degrades the release coating layer, which leads to defects in pattern replication and eventual breakage of the mold. Therefore, optimal conditions for release coating are required. In addition, the recommended 1000 imprints for assessing the release properties in UV-NIL are extremely time consuming. The authors believed that the durability of the release layer could be varied by using a mold with a large surface area and previously fabricated such a mold to successfully transfer a high-aspect-ratio (>15) nanoscale pattern. In the present study, the authors used this method to investigate the optimal conditions for release coating and to assess the release properties in UV-NIL according to the measured release force and number of replication times. As a result, the conditions for release coating were optimized as follows: dipping time of 24 h, postrinsing bake temperature of 100 °C, and baking time of 3 min in a high-aspect-ratio mold with a 1300 nm pattern height. Low release force led to extended lifetime of the release coating layer in an accelerated durability test using a large-surface-area mold.
Effects of salty-developer temperature on electron-beam-exposed hydrogen silsesquioxane resist for ultradense pattern transfer
Authors: Yan M. , Lee J. , Ofuonye B. , Choi S. , Jang J. H. , Adesida I.
Published: November 2010

The characteristics of salty developers, TMAH/NaCl and NaOH/NaCl, on the processing of hydrogen silsesquioxane (HSQ) resist at elevated temperatures were investigated. The TMAH/NaCl developer demonstrated better contrast than the NaOH/NaCl developer at the temperatures (20–35 °C) investigated for both the unbaked and prebaked HSQ resists. The higher contrast developer was utilized to investigate the fabrication of ultradense gratings. Better reproducibility of the gratings was obtained from prebaked HSQ resist even though unbaked HSQ exhibited higher contrast. The ultradense grating patterns realized in HSQ resist was successfully transferred into a Si substrate. By employing the TMAH/NaCl development process at an elevated temperature and the inductively coupled plasma reactive ion etching process, 20-nm-pitch silicon nanowire arrays were demonstrated.
Evaluation of oxygen inhibition for UV-curable resins by adhesion force measurement using scanning probe microscope
Authors: Okada Makoto , Iwasa Masayuki , Miyake Hiroto , Ohsaki Takeshi , Haruyama Yuichi , Kanda Kazuhiro , Matsui Shinji
Published: November 2010

UV nanoimprint lithography is used to fabricate nanostructure devices with high throughput, low cost, and high resolution. UV-curable resins are one important factor in UV nanoimprinting and they are mainly categorized into two reaction types: radical and cationic curing systems. A drawback of the radical curing system is curing inhibition by oxygen. To evaluate the oxygen inhibition for UV-curable resins, the authors measured the force curve transition by scanning probe microscopy with an UV irradiation system. With this system, the authors are able to measure in situ the UV dose dependence of the force curve transition on the same UV-curable resin. Measurements showed that the curing speed of radical UV-curable resin in vacuum became 800 times higher than that in air due to oxygen inhibition. Furthermore, for a cationic UV-curable resin, although the curing reaction of a cationic UV-curable resin is not affected by oxygen, the authors observed that the curing speed in vacuum at about 15 Pa became 4.5 times higher compared to that in air. The curing reaction of a cationic UV-curable resin may be inhibited by alkali.