bluuebunny/crossref_metadata_2025 huggingface dataset:
Prognostic Value of Chromogranin A at Admission in Critically Ill Patients: A Cohort Study in a Medical Intensive Care Unit
Authors: Zhang Dan , Lavaux Thomas , Voegeli Anne-Claire , Lavigne Thierry , Castelain Vincent , Meyer Nicolas , Sapin Rémy , Aunis Dominique , Metz-Boutigue Marie-Hélène , Schneider Francis
Published: July 2008

Background: Risk assessments of patients should be based on objective variables, such as biological markers that can be measured routinely. The acute response to stress causes the release of catecholamines from the adrenal medulla accompanied by chromogranin A (CGA). To date, no study has evaluated the prognostic value of CGA in critically ill intensive care unit patients.

Methods: We conducted a prospective study of intensive care unit patients by measuring serum procalcitonin (PCT), C-reactive protein (CRP), and CGA at the time of admission. Univariate and multivariate analyses were performed to evaluate the ability of these biomarkers to predict mortality.

Results: In 120 consecutive patients, we found positive correlations between CGA and the following: CRP (r2 = 0.216; P = 0.02), PCT (r2 = 0.396; P < 0.001), Simplified Acute Physiologic Score II (SAPS II) (r2 = 0.438; P < 0.001), and the Logistic Organ Dysfunction System (LODS) score (r2 = 0.374; P < 0.001). Nonsurvivors had significantly higher CGA and PCT concentrations than survivors [median (interquartile range): 293.0 μg/L (163.5–699.5 μg/L) vs 86.0 μg/L (53.8–175.3 μg/L) for CGA, and 6.78 μg/L (2.39–22.92 μg/L) vs 0.54 μg/L (0.16–6.28 μg/L) for PCT; P < 0.001 for both comparisons]. In a multivariable linear regression analysis, creatinine (P < 0.001), age (P < 0.001), and SAPS II (P = 0.002) were the only significant independent variables predicting CGA concentration (r2 = 0.352). A multivariate Cox regression analysis identified 3 independent factors predicting death: log-normalized CGA concentration [hazard ratio (HR), 7.248; 95% confidence interval (CI), 3.004–17.487], SAPS II (HR, 1.046; 95% CI, 1.026–1.067), and cardiogenic shock (HR, 3.920; 95% CI, 1.731–8.880).

Conclusions: CGA is a strong and independent indicator of prognosis in critically ill nonsurgical patients.
Pitfalls and Prevention Strategies for Liquid Chromatography-Tandem Mass Spectrometry in the Selected Reaction– Monitoring Mode for Drug Analysis
Authors: Sauvage François-Ludovic , Gaulier Jean-Michel , Lachâtre Gérard , Marquet Pierre
Published: July 2008

Background: We observed cases of false-positive results with the use of liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Different LC-MS/MS techniques that use the selected reaction-monitoring mode, routinely employed for the analysis and quantification of drugs and toxic compounds in biological matrices, were involved in the false-positive and potentially false-positive results obtained. We sought to analyze the causes of and solutions to this problem.

Methods: We used a previously reported LC-MS/MS general unknown screening method, as well as manual spectral investigation in 1 case, to perform verification and identification of interfering compounds.

Results: We observed that false-positive results involved: a metabolite of zolpidem that might have been mistaken for lysergic acid diethylamide, benzoylecgonine mistaken for atropine, and clomipramine and 3 phenothiazines that share several common ion transitions.

Conclusions: To prevent problems such as those we experienced, we recommend the use of stable-isotope internal standards when possible, relative retention times, 2 transitions or more per compound when possible, and acceptable relative abundance ratios between transitions, with an experience-based tolerance of ±15% for transitions with a relative abundance >10% and with an extension to ±25% for transitions <10% when the concentration is at the limit of quantification. A powerful general unknown screening procedure can help to confirm suspected interferences. Our results indicate that the specificity of screening procedures is questionable for LC-MS/MS analyses performed in the selected reaction-monitoring mode and involving a large number of compounds with only 1 transition per compound.
Trueness verification of actual creatinine assays in the European market demonstrates a disappointing variability that needs substantial improvement. An international study in the framework of the EC4 creatinine standardization working group
Authors: Delanghe Joris R. , Cobbaert Christa , Galteau Marie-Madeleine , Harmoinen Aimo , Jansen Rob , Kruse Rolf , Laitinen Päivi , Thienpont Linda M. , Wuyts Birgitte , Weykamp Cas , Panteghini Mauro
Published: July 2008

: The European In Vitro Diagnostics (IVD) directive requires traceability to reference methods and materials of analytes. It is a task of the profession to verify the trueness of results and IVD compatibility.

: The results of a trueness verification study by the European Communities Confederation of Clinical Chemistry (EC4) working group on creatinine standardization are described, in which 189 European laboratories analyzed serum creatinine in a commutable serum-based material, using analytical systems from seven companies. Values were targeted using isotope dilution gas chromatography/mass spectrometry. Results were tested on their compliance to a set of three criteria: trueness, i.e., no significant bias relative to the target value, between-laboratory variation and within-laboratory variation relative to the maximum allowable error.

: For the lower and intermediate level, values differed significantly from the target value in the Jaffe and the dry chemistry methods. At the high level, dry chemistry yielded higher results. Between-laboratory coefficients of variation ranged from 4.37% to 8.74%. Total error budget was mainly consumed by the bias. Non-compensated Jaffe methods largely exceeded the total error budget. Best results were obtained for the enzymatic method. The dry chemistry method consumed a large part of its error budget due to calibration bias.

: Despite the European IVD directive and the growing needs for creatinine standardization, an unacceptable inter-laboratory variation was observed, which was mainly due to calibration differences. The calibration variation has major clinical consequences, in particular in pediatrics, where reference ranges for serum and plasma creatinine are low, and in the estimation of glomerular filtration rate.

Clin Chem Lab Med 2008;46:1319–25.
Migration of Neurotrophic Factors-Secreting Mesenchymal Stem Cells Toward a Quinolinic Acid Lesion as Viewed by Magnetic Resonance Imaging
Authors: Sadan Ofer , Shemesh Noam , Barzilay Ran , Bahat-Stromza Merav , Melamed Eldad , Cohen Yoram , Offen Daniel
Published: July 2008

Stem cell-based treatment is a promising frontier for neurodegenerative diseases. We propose a novel protocol for inducing the differentiation of rat mesenchymal stem cells (MSCs) toward neurotrophic factor (NTF)-secreting cells as a possible neuroprotective agent. One of the major caveats of stem cell transplantation is their fate post-transplantation. To test the viability of the cells, we tracked the transplanted cells in vivo by magnetic resonance imaging (MRI) scans and validated the results by histology. MSCs went through a two-step medium-based differentiation protocol, followed by in vitro characterization using immunocytochemistry and immunoblotting analysis of the cell media. We examined the migratory properties of the cells in the quinolinic acid (QA)-induced striatal lesion model for Huntington's disease. The induced cells were labeled and transplanted posterior to the lesion. Rats underwent serial MRI scans to detect cell migration in vivo. On the 19th day, animals were sacrificed, and their brains were removed for immunostaining. Rat MSCs postinduction exhibited both neuronal and astrocyte markers, as well as production and secretion of NTFs. High-resolution two-dimensional and three-dimensional magnetic resonance images revealed that the cells migrated along a distinct route toward the lesion. The in vivo MRI results were validated by the histological study, which demonstrated that phagocytosis had only partially occurred and that MRI could correctly depict the status of the migrating cells. The results show that these cells migrated toward a QA lesion and therefore survived for 19 days post-transplantation. This gives hope for future research harnessing these cells for treating neurodegenerative diseases.

Disclosure of potential conflicts of interest is found at the end of this article.
The ground: clients remain exposed to unnecessary risk
Authors: Egan D.
Published: July 2008

The ground remains the greatest source of risk to construction projects. In spite of a wealth of freely available information and guidance on the central importance of adequate site investigation in managing ground risk, many clients remain unnecessarily exposed to risk due to inadequate site investigation. The Federation of Piling Specialists undertook a comprehensive survey of geotechnical designers within its membership to evaluate the usefulness of site investigation information routinely provided to them. For nearly a third of all the piling and specialist geotechnical contracts surveyed, the site investigation information provided was poor, preventing optimisation of the foundation solution. The cost to clients arising out of poor site investigations far exceeds the savings that could be made by following good practice when investing in a site investigation. The survey indicates that good practice guidance is not being followed, resulting in investigations that are not adequately designed, specified or supervised.
Response of granular pile-anchors under compression
Authors: Srirama Rao A. , Phanikumar B. R. , Suresh K.
Published: July 2008

The granular pile anchor (GPA) is an innovative foundation technique, devised for mitigating heave of expansive clay beds and improving their engineering behaviour. It is a modification of the conventional granular pile wherein an anchor is provided in the pile to render it tension-resistant. This paper presents the results of a field-scale test programme conducted to study the response of anchors embedded in expansive clay beds. Plate load tests were conducted on unreinforced expansive clay beds and clay beds reinforced with GPAs to compare the compressive load response. The bulging pattern of the anchors was also studied. It was found from the field load tests that expansive clay beds reinforced with GPAs showed higher load-carrying capacity and improved compressive load response than unreinforced clay beds. Whereas the stress required to cause a settlement of 25 mm in the unreinforced expansive clay bed was 200 kN/m2, the clay bed reinforced with a GPA 1000 mm long and 150 mm in diameter (lgp/dgp=6·67) required 500 kN/m2to cause the same settlement, showing an improvement of 150%. Of the various single anchors with lgp/dgp values between 2.5 and 10, that of length 1000 mm and diameter 100 mm (lgp/dgp=10) showed the best load response when tested alone, resulting in an improvement of 440%. The maximum bulge diameter increased with increasing diameter and length of the GPA. The effect of GPA length is more pronounced in the increase in maximum bulge length than that of diameter.
Seismic response evaluation of sites improved by deep mixing, Part I: Proposed approach
Authors: Siddharthan R. V. , Porbaha A.
Published: July 2008

The objective of this paper is to develop a simplified design procedure to aid designers in selecting the optimum design of deep-mixing (DM) dimensions for a site treated using DM technology. This was accomplished based on a parametric study that focused on the influence of many important variables that affect the seismic behaviour of DM-treated soils. A two-dimensional effective stress program (TARA-2M) was used in the parametric study. The procedures developed provide the residual pore water pressure at DM-treated sites at various locations within and around the DM columns. The proposed simplified approach extends the routinely used and well-established liquefaction evaluation procedure for one-dimensional soil deposits to DM-treated sites based on seismic response results from the TARA-2M parametric study. The companion paper presents the verification of the proposed approach.
Seismic response evaluation of sites improved by deep mixing, Part 2: Verification
Authors: Siddharthan R. V. , Porbaha A.
Published: July 2008

This paper presents verification of the simplified approach for seismic response evaluation of sites improved by deep mixing proposed in the companion paper. The results from centrifuge tests that measured the pore water pressure responses of many deep mixing treatment configurations and a field case have been used to verify the applicability of the proposed simplified approach. A menudriven, windows-based software package was developed to incorporate the steps in the proposed approach and allow practising engineers to consider many design scenarios involving various deep mixing configurations, site and excitation conditions for optimum design.
Theoretical and experimental study of roller-compacted concrete strength
Authors: Zdiri M. , Ben Ouezdou M. , Neji J.
Published: July 2008

Roller-compacted concrete (RCC) is presented as an evolutionary technology for a large diversity of applications: dams, roads, parking areas. The present work considers a road application and uses some materials of local quarries. The development of compressive and tensile strengths of RCC with the specification of a low cement content is discussed. The current study treats the characterisation of different granular constituents based on local materials quarries, the formulation of various granular mixtures, by the compressive packing model ‘René-LCPC’, and the simulation by theoretical models developed by Feret, de Larrard and Tondat for the evaluation of compressive and tensile strengths. Compression and Brazilian tensile (by splitting) tests were performed on the cylindrical specimens type ‘16/32 cm’, prepared according to the National French Project Method ‘BaCaRa’. A comparison was therefore made between the experimental and the theoretical model results, showing a good agreement between both.
Code modelling of reinforced-concrete deep beams
Authors: Yang K.-H. , Ashour A. F.
Published: July 2008

Code provisions for shear design of deep beams have commonly developed from limited test results. There are also very few studies on the validity of shear-carrying capacities of concrete and shear reinforcement in code provisions including strut-and-tie models. The present study investigates the effect of different parameters on the shear-carrying capacities of concrete and shear reinforcement in four code provisions: ACI 318-99 and CIRIA Guide 2 for empirical formulae, and ACI 318-05 and Eurocode (EC) 2 for strut-and-tie models. A comprehensive database having a total of 448 simple and 73 continuous deep beam test results was compiled and compared with the code provisions. Different statistical parameters to measure the safety and accuracy of code provisions are also presented for various web reinforcement arrangements. Code provisions generally fail adequately to capture the effect of different parameters on the shear capacities of concrete and shear reinforcement in deep beams, indicating that shear capacities predicted from empirical code provisions and the strut-and-tie model of ACI 318-05 are more unconservative in continuous deep beams than in simple deep beams, while the strut-and-tie model of EC2 is more unconservative in simple deep beams than in continuous deep beams. In addition, a higher unconservatism appears in strut-and-tie models than in empirical formulae.
Trends in streamflow of the Euphrates basin, Turkey
Authors: Yenigün K. , Gümüş V. , Bulut H.
Published: July 2008

Detection of changes over the long term for a series of hydrological variables is an important and critical issue, which is subject to increasing interest. In this study, trend analysis of the streamflow of the Euphrates basin, which is the biggest basin in Turkey, is carried out. The non-parametric trend tests (Mann–Kendall and Spearman's rho) are applied to annual average, minimum and maximum streamflow data of 22 selected stations in the Euphrates basin. All the streamflow records date back over at least 24 years, with lengths in the range 24–44 years. The Mann–Kendal rank correlation test is used to determine the year in which trends begin. The linear slopes of trends are calculated by using Sen's estimator of slope technique. Based on the test's procedures, with respect to annual minimum streamflow, significant decreasing trends are detected for six stations and an upward trend is found for only one station. While no trend appears relating to annual maximum streamflow for any station, a decreasing trend is found with respect to annual mean streamflow for one station. The results are expected to assist water resources managers and policy makers in making better planning decisions in the Euphrates basin.
Statistical analysis of structural failures of water pipes
Authors: Dehghan A. , McManus K. J. , Gad E. F.
Published: July 2008

Statistical analysis and prediction of failure rates of water distribution pipes are usually performed using parametric lifetime models. In this paper, a new probabilistic measure for the failure rate, called the ‘likelihood of number of failures’, is defined and formulated for cases where the pipe lifetimes follow parametric models. The resulting theoretical failure rates are time-invariant and, therefore, the parametric models would be useful only if the failure rates of water distribution pipes are stationary random processes. This paper then examines the stationarity of pipe failure rates in practice. For the water pipes in the western district of Melbourne (Australia), the failure rates are empirically calculated using a 4-year failure history, and it is observed that the distribution of empirical failure rates varies with time. In order to explain these variations, the pattern of rainfall in the region is compared with the pattern of failure rate variations, and in 70% of the times the two patterns are observed to be consistent. Two approaches are proposed to tackle the time-varying nature of pipe failure rate processes: regular updating of the parameters of lifetime models or developing a non-parametric technique for modelling of pipe failure rates.
Understanding blockage formation in combined sewer networks
Authors: Arthur S. , Crow H. , Pedezert L.
Published: July 2008

This paper documents a key part of the development of a risk analysis process that may be used as a tool to manage maintenance expenditure within the context of ‘serviceability’ to customers, the public and the environment. Against the background of poor availability of reliable data, the text outlines the basis of a methodology that can be used to model blockage likelihood in combined sewers with limited information and without the need for additional data gathering. Specifically, the work reported here relates primarily to research undertaken to better understand what network-and catchment-specific factors influence the formation of blockages that lead to flooding in combined and foul drainage systems. The role of each of these factors is considered in turn and the significance of their impact is estimated.
Ecological and evolutionary bioprospecting: using aposematic insects as guides to rainforest plants active against disease
Authors: Helson Julie E , Capson Todd L , Johns Timothy , Aiello Annette , Windsor Donald M
Published: July 2008

We examined Coleoptera and Lepidoptera assemblages feeding on two different groups of plants: one in which plants were active against cancer cell lines and/or protozoan parasites responsible for tropical parasitic diseases, and a second group that was inactive in the same bioassays. Aposematic species were found on nine of the ten active plant species, but on only four of the ten inactive plant species. Non‐aposematic insects did not show a significant difference in their association with active versus inactive plants. Our results suggest that the presence of aposematic, herbivorous insects can be used to facilitate the identification of plants with compounds active against important human diseases.
Toward a nontoxic poison: Current trends in (European union) biocides regulation
Authors: Kähkönen Elina , Nordström Katrina
Published: July 2008

The number of products containing biocides is increasing at the same time as the number of available biocides is decreasing. Biocides are biologically active chemicals with a vast area of applications where demands for maintaining product quality by use of biocides presents a major challenge for developers striving to meet emerging environmental concerns and fulfilling criteria for eco-labeled consumer products. Tightening regulations have, however, led to stagnation in the current development of new biocide chemistries, and the “nontoxic poison” has yet to be formulated. Accordingly, the present article presents a critical overview of European Union regulation of biocides and their usage and of some of the future challenges for meeting demands for environmentally safe products and processes in which biocides are used. The Biocidal Product Directive, which is presently implemented, is one focus in the present article. Regulations of environmental, health, and safety (EHS) risk classifications and their role in the future development of biocide-containing products are also discussed. Studying the biocide dilemma may provide tools for the chemical industry as whole for proactive anticipation of the effect of emerging regulatory demands on product development.
R fluids
Authors: Caimmi R.
Published: July 2008

A theory of collisionless fluids is developed in a unified picture, where nonrotating (?f1 = ?f2 = ?f3 = 0) figures with some given random velocity component distributions, and rotating (?f1 = ?f2 = ?f3 ) figures with a different random velocity component distributions, make adjoint configurations to the same system. R fluids are defined as ideal, self-gravitating fluids satisfying the virial theorem assumptions, in presence of systematic rotation around each of the principal axes of inertia. To this aim, mean and rms angular velocities and mean and rms tangential velocity components are expressed, by weighting on the moment of inertia and the mass, respectively. The figure rotation is defined as the mean angular velocity, weighted on the moment of inertia, with respect to a selected axis. The generalized tensor virial equations (Caimmi and Marmo 2005) are formulated for R fluids and further attention is devoted to axisymmetric configurations where, for selected coordinate axes, a variation in figure rotation has to be counterbalanced by a variation in anisotropy excess and vice versa. A microscopical analysis of systematic and random motions is performed under a few general hypotheses, by reversing the sign of tangential or axial velocity components of an assigned fraction of particles, leaving the distribution function and other parameters unchanged (Meza 2002). The application of the reversion process to tangential velocity components is found to imply the conversion of random motion rotation kinetic energy into systematic motion rotation kinetic energy. The application of the reversion process to axial velocity components is found to imply the conversion of random motion translation kinetic energy into systematic motion translation kinetic energy, and the loss related to a change of reference frame is expressed in terms of systematic motion (imaginary) rotation kinetic energy. A number of special situations are investigated in greater detail. It is found that an R fluid always admits an adjoint configuration where figure rotation occurs around only one principal axis of inertia (R3 fluid), which implies that all the results related to R3 fluids (Caimmi 2007) may be ex- tended to R fluids. Finally, a procedure is sketched for deriving the spin parameter distribution (including imaginary rotation) from a sample of observed or simulated large-scale collisionless fluids i.e. galaxies and galaxy clusters.
Minihalo model for the low-redshift Lyα absorbers revisited
Authors: Lalovic A. , Cirkovic M.M.
Published: July 2008

We reconsider the basic properties of the classical minihalo model of Rees and Milgrom in light of the new work, both observational (on 'dark galaxies' and masses of baryonic haloes) and theoretical (on the cosmological mass function and the history of star formation). In particular, we show that more detailed models of ionized gas in haloes of dark matter following isothermal and Navarro-Frenk-White density profile can effectively reproduce particular aspects of the observed column density distribution function in a heterogeneous sample of low- and intermediate-redshift Ly? forest absorption lines.
Optical spectra of radio planetary nebulae in the small Magellanic cloud
Authors: Payne J.L. , Filipovic M.D. , Crawford E.J. , de Horta , White G.L. , Stootman F.H.
Published: July 2008

We present preliminary results from spectral observations of four (4) candidate radio sources co-identified with known planetary nebulae (PNe) in the Small Magellanic Cloud (SMC). These were made using the Radcliffe 1.9-meter telescope in Sutherland, South Africa. These radio PNe were originally found in Australia Telescope Compact Array (ATCA) surveys of the SMC at 1.42 and 2.37 GHz, and were further confirmed by new high resolution ATCA images at 6 and 3 cm (400 /200 ). Optical PNe and radio candidates are within 200 and may represent a sub- population of selected radio bright objects. Nebular ionized masses of these objects may be 2.6 Mo or greater, supporting the existence of PNe progenitor central stars with masses up to 8 Mo.
Coronal microleakage in intact and carious teeth obturated using lateral compaction of gutta-percha
Authors: Djeri Aleksandra , Sukara S. , Arbutina R. , Trnic Z. , Gajic N.
Published: July 2008

Introduction: Coronal microleakage is one of the most important factors for the success and longevity of endodontically treated teeth. Aim: The aim of this study was to evaluate in vitro the coronal microleakage in carious and intact teeth obturated with lateral compaction of gutta-percha using the dye penetration method. Materials and Methods: Forty extracted human teeth were allocated to two groups: Group I consisted of 20 intact teeth (10 single-rooted and 10 multi-rooted) and Group II comprised 20 carious teeth (10 single-rooted and 10 multi-rooted). Root canal preparation was performed using the Step-back technique and copious irrigation with 2.5% NaOCl. All root canals were obturated using lateral compaction and AH Plus endodontic sealer. The teeth were coronally filled with either CAVIT only or the combination of GIC and CAVIT, coated with 2 layers of nail varnish and immersed in 50% AgNO3. Afterwards, the teeth were sectioned mesio-distally using a diamond disc and linear dye penetration was evaluated using a stereo loupe with a micrometer scale at x6 magnification. Results: The results showed dye penetration in 70% of teeth filled with CAVIT and in 10% of teeth filled with GIC+CAVIT. The difference was statistically significant (p<0.05). Conclusion: Based on the obtained results, it may be concluded that the least coronal microleakage was observed in intact teeth temporarily filled with the GIC+CAVIT combination.
Oral health in individuals with psychotic disorders
Authors: Jovanovic Svetlana , Gajic Ivanka
Published: July 2008

Mental disorders are an important problem in every national health care service. The importance of psychotic disorders is not only their frequency but also their long-term character, recurrence, association with other diseases, costs and consequences for the family and society. Psychotic disorders (schizophrenia, schizoaffective disorder, bipolar disorders and depression) and their treatment may result in serious oral diseases. These disorders and medications used to treat them may lead to a series of oral complications and side effects, predominantly high prevalence of carious and extracted teeth, periodontal disease, inadequate oral hygiene, xerostomia, burning mouth syndrome, bad breath and gustatory sense dysfunction. Psychotic disorders affect oral and dental health in two ways. Behavioral changes affect the oral hygiene maintenance and lead to bad habits and attitudes towards oral health. Antipsychotic therapy has adverse effects on oral health. Literature data suggest that oral health in patients with psychotic disorders is poor and highlight the need to develop specific preventive programmes, which would be aimed at improving behavior of this population at risk in the oral health care system.
Measurement of phase interaction in dispersed gas-particle two-phase flow by phase-doppler anemometry
Authors: Mergheni Ali , Ben Ticha , Sautet Jen-Charles , Godard Gille , Ben Nasrallah
Published: July 2008

For simultaneous measurement of size and velocity distributions of continuous and dispersed phases in a two-phase flow a technique phase-Doppler anemometry was used. Spherical glass particles with a particle diameter range from 102 up to 212 ?m were used. In this two-phase flow an experimental results are presented which indicate a significant influence of the solid particles on the flow characteristics. The height of influence of these effects depends on the local position in the jet. Near the nozzle exit high gas velocity gradients exist and therefore high turbulence production in the shear layer of the jet is observed. Here the turbulence intensity in the two-phase jet is decreased compared to the single-phase jet. In the developed zone the velocity gradient in the shear layer is lower and the turbulence intensity reduction is higher. .
Thermal and hydrodynamic characteristics of forced and mixed convection flow through vertical rectangular channels
Authors: Hanafi Abdalla , Mahmoud Safaa , Elbakhshawangy Hesham
Published: July 2008

This paper presents experimental and numerical studies for the case of turbulent forced and mixed convection flow of water through narrow vertical rectangular channel. The channel is composed of two parallel plates which are heated at a uniform heat flux, whereas, the other two sides of the channel are thermally insulated. The plates are of 64 mm in width, 800 mm in height, and separated from each other at a narrow gap of 2.7 mm. The Nusselt number distribution along the flow direction normalized by the Nusselt number for the case of turbulent forced convection flow is obtained experimentally with a comparison with the numerical results obtained from a commercial computer code. The quantitative determination of the nor- malized Nusselt number with respect to the dimension-less number Z = (Gr/Re21/8Pr0.5) is presented with a comparison with previous experimental results. Qualitative results are presented for the normalized temperature and velocity profiles in the transverse direction with a comparison between the forced and mixed convection flow for both the cases of upward and downward flow directions. The effect of the axial locations and the parameter Gr/Re on the variation of the normalized temperature profiles in the transverse direction for both the regions of forced and mixed convection and for both of the upward and downward flow directions are obtained. The normalized velocity profiles in the transverse directions are also determined at different inlet velocity and heat fluxes for the previous cases. It is found that the normalized Nusselt number is greater than one in the mixed convection region for both the cases of upward and downward flow and correlated well with the dimension-less parameter Z for both of the forced and mixed convection regions. The temperature profiles increase with increasing the axial location along the flow direction or the parameter Gr/Re for both of the forced and mixed convection regions, but this increase is more pronounced in the case of the mixed convection flow. For the forced convection region, the velocity profile depends only on Re with no difference between the upward and downward flow directions. Whereas, for the case of mixed convection flow, the velocity profile depends on the parameter Gr/Re with a main difference between upward and downward flow. These results are of great importance for any research reactor using plate type fuel elements or for any engineering application in which mixed convection flow through rectangular channel is encountered. .
Determination of thermal conductivity of rocks samples using fabricated equipment
Authors: Fasunwon Olusola , Olowofela John , Ocan Ojok , Akinyemi Olukayode
Published: July 2008

The aim of the paper is to describe how inexpensive/simple physics equipment was fabricated and used in the determination of thermal conductivity of rock samples. We used the experimental techniques known as transient method of measuring thermal properties of rock samples at ambient temperature. We investigated samples found in five locations/region (Ewekoro, Ile-Ife, Igara, Ago-Iwoye, Abeokuta) in South western Nigeria. Those samples are limestone, dolerite, marble, gneiss, and granite. Although the samples are multi-mineral as revealed by photomicrograph, the thermal conductivity results obtained 1.40, 1.50, 1.57, 1.75, and 2.94 W/m?C, respectively, are found to be consistent with the ones in literature where highly expensive and sophisticated (not easily affordable in developing nation) equipment are used. .
A numerical study of flow and temperature fields in circular tube heat exchanger with elliptic vortex generators
Authors: Mohseni-Languri Ehsan , Gorji-Bandpy Mofid , Masoodi Reza
Published: July 2008

The two-dimensional fluid flow and heat transfer in a circular tube heat exchanger with two elliptic obstacles at the back is studied numerically. The computational domain consists of a circular tube and two elliptic obstacles that are situated after the tube, such that the angle between their centerlines and the direction of free coming flow is 45 degrees. The numerical solution is achieved by numerical integration of full Navier-Stokes and energy equations over the computational domain, using finite volume method. The fluid flow is assumed to be laminar, incompressible and steady-state with constant thermo-physical characteristics. In this study major thermo-fluid parameters such as temperature, pressure and velocity fields as well as Nusselt number and friction factor variations are computed and some results are presented in the graphs. It is shown that using of elliptic obstacles leads to an increase in the average Nusselt number and also pressure. .
The inverse maximum flow problem with lower and upper bounds for the flow
Authors: Deaconu Adrian
Published: July 2008

The general inverse maximum flow problem (denoted GIMF) is considered, where lower and upper bounds for the flow are changed so that a given feasible flow becomes a maximum flow and the distance (considering l1 norm) between the initial vector of bounds and the modified vector is minimum. Strongly and weakly polynomial algorithms for solving this problem are proposed. In the paper it is also proved that the inverse maximum flow problem where only the upper bound for the flow is changed (IMF) is a particular case of the GIMF problem.
Nonlinear receding horizon control of production inventory systems with deteriorating items
Authors: Bounkhel M. , Tadj L. , Hedjar R.
Published: July 2008

This paper is concerned with the receding horizon control of the production rate of a deteriorating production system with a nonlinear inventory-level-dependent demand. Both continuous and periodic review policies are discussed and numerical illustrations are provided. .
A multi-step curve search algorithm in nonlinear optimization
Authors: Djuranovic-Milicic Nada
Published: July 2008

In this paper a multi-step algorithm for LC1 unconstrained optimization problems is presented. This method uses previous multi-step iterative information and curve search to generate new iterative points. A convergence proof is given, as well as an estimate of the rate of convergence.
An intrusion prevention system as a proactive security mechanism in network infrastructure
Authors: Dulanovic Nenad , Hinic Dane , Simic Dejan
Published: July 2008

A properly configured firewall is a good starting point in securing a computer network. However, complex network environments that involve higher number of participants and endpoints require better security infrastructure. Intrusion Detection Systems (IDS), proposed as a solution to perimeter defense, have many open problems and it is clear that better solutions must be found. Due to many unsolved problems associated with IDS, Intrusion Prevention Systems (IPS) are introduced. The main idea in IPS is to be proactive. This paper gives an insight of Cobrador Bouncer IPS implementation. System architecture is given and three different Bouncer IPS deployment modes are presented. The Bouncer IPS as a proactive honeypot is also discussed.
Document representations for classification of short web-page descriptions
Authors: Radovanovic Milos , Ivanovic Mirjana
Published: July 2008

Motivated by applying Text Categorization to classification of Web search results, this paper describes an extensive experimental study of the impact of bag-of- words document representations on the performance of five major classifiers - Na?ve Bayes, SVM, Voted Perceptron, kNN and C4.5. The texts, representing short Web-page descriptions sorted into a large hierarchy of topics, are taken from the dmoz Open Directory Web-page ontology, and classifiers are trained to automatically determine the topics which may be relevant to a previously unseen Web-page. Different transformations of input data: stemming, normalization, logtf and idf, together with dimensionality reduction, are found to have a statistically significant improving or degrading effect on classification performance measured by classical metrics - accuracy, precision, recall, F1 and F2. The emphasis of the study is not on determining the best document representation which corresponds to each classifier, but rather on describing the effects of every individual transformation on classification, together with their mutual relationships. .
Relics: Penguin Population Programs
Authors: Sun Liguang , Xie Zhouqing
Published: July 2008

What has been responsible for the increase in Chinstrap penguin populations during the past 40 years in maritime Antarctica? One view ascribes it to an increase in availability of their prey brought on by the decrease in baleen whale stocks. The contrary opinion, attributes it to environmental warming. This causes a gradual decrease in the frequency of cold years with extensive winter sea ice cover. A number of penguin monitoring programs are in progress and are expected to provide some answers to these questions. Unfortunately, it is not easy to distinguish natural variability from anthropogenic change since penguins are easily accessible predators of krill and the feeding range of the penguins has almost overlapped with the krill fishery in time and space in the last four decades. Therefore it is important to reconstruct the change of ancient penguin abundance and distribution in the absence of human activity. Many efforts have focused on surveying the abandoned penguin rookeries, but this method has not been able to give a continuous historical record of penguin populations. In several recent studies, ancient penguin excreta was scooped from the penguin relics in the sediments of the lake on penguin rookery, Ardley Island, maritime Antarctica. In these studies, penguin droppings or guano soil deposited in the lake and changes in sediment geochemistry have been used to calculate penguin population changes based upon the geochemical composition of the sediment core. The results suggest that climate change has a significant impact on penguin populations.
Bacterial Cold Shock Responses
Authors: Weber Michael H.W. , Marahiel Mohamed A.
Published: July 2008

As a measure for molecular motion, temperature is one of the most important environmental factors for life as it directly influences structural and hence functional properties of cellular components. After a sudden increase in ambient temperature, which is termed heat shock, bacteria respond by expressing a specific set of genes whose protein products are designed to mainly cope with heat-induced alterations of protein conformation. This heat shock response comprises the expression of protein chaperones and proteases, and is under central control of an alternative sigma factor (σ32) which acts as a master regulator that specifically directs RNA polymerase to transcribe from the heat shock promotors. In a similar manner, bacteria express a well-defined set of proteins after a rapid decrease in temperature, which is termed cold shock. This protein set, however, is different from that expressed under heat shock conditions and predominantly comprises proteins such as helicases, nucleases, and ribosome-associated components that directly or indirectly interact with the biological information molecules DNA and RNA. Interestingly, in contrast to the heat shock response, to date no cold-specific sigma factor has been identified. Rather, it appears that the cold shock response is organized as a complex stimulon in which post-transcriptional events play an important role. In this review, we present a summary of research results that have been acquired in recent years by examinations of bacterial cold shock responses. Important processes such as cold signal perception, membrane adaptation, and the modification of the translation apparatus are discussed together with many other cold-relevant aspects of bacterial physiology and first attempts are made to dissect the cold shock stimulon into less complex regulatory subunits. Special emphasis is placed on findings concerning the nucleic acid-binding cold shock proteins which play a fundamental role not only during cold shock adaptation but also under optimal growth conditions.
A cooperative neural dynamic model for solving general convex nonlinear optimization problems with fuzzy parameters and an application in manufacturing systems
Authors: Jahangiri Mohammadreza , Nazemi Alireza
Published: April 2024

In the presented study, the solution of the fuzzy nonlinear optimization problems (FNLOPs) is calculated using a recurrent neural network (RNN) model. Since there is a few research for solving FNLOP by RNN's, we give a new approach to solve the problem. By reducing the original program to an interval problem and then weighting problem, the Karush–Kuhn–Tucker (KKT) conditions are given. Moreover, we use the KKT conditions into a RNN as an important tool to solve the problem. Besides, the global convergence properties and the Lyapunov stability of the dynamic model are studied in this study. In the final step, some illustrative examples are considered to establish the obtained results. Reported results are compared with some others network models.
Cell Membrane‐Camouflaged Chitosan‐Polypyrrole Nanogels Co‐Deliver Drug and Gene for Targeted Chemotherapy and Bone Metastasis Inhibition of Prostate Cancer
Authors: Yu Qiuyu , Gao Yue , Dai Waicong , Li Danni , Zhang Lu , Hameed Meera Moydeen Abdul , Guo Rui , Liu Min , Shi Xiangyang , Cao Xueyan
Published: April 2024

The development of functional nanoplatforms to improve the chemotherapy outcome and inhibit distal cancer cell metastasis remains an extreme challenge in cancer management. In this work, a human‐derived PC‐3 cancer cell membrane‐camouflaged chitosan‐polypyrrole nanogel (CH‐PPy NG) platform, which can be loaded with chemotherapeutic drug docetaxel (DTX) and RANK siRNA for targeted chemotherapy and gene silencing‐mediated metastasis inhibition of late‐stage prostate cancer in a mouse model, is reported. The prepared NGs with a size of 155.8 nm show good biocompatibility, pH‐responsive drug release profile, and homologous targeting specificity to cancer cells, allowing for efficient and precise drug/gene co‐delivery. Through in‐vivo antitumor treatment in a xenografted PC‐3 mouse tumor model, it is shown that such a CH‐PPy NG‐facilitated co‐delivery system allows for effective chemotherapy to slow down the tumor growth rate, and effectively inhibits the metastasis of prostate cancer to the bone via downregulation of the RANK/RANKL signaling pathway. The created CH‐Ppy NGs may be utilized as a promising platform for enhanced chemotherapy and anti‐metastasis treatment of prostate cancer.
Ruthenium‐Based Binary Alloy with Oxide Nanosheath for Highly Efficient and Stable Oxygen Evolution Reaction in Acidic Media
Authors: Chen Jinghao , Ma Yirui , Huang Tao , Jiang Taoli , Park Sunhyeong , Xu Jingwen , Wang Xiaoyang , Peng Qia , Liu Shuang , Wang Gongming , Chen Wei
Published: April 2024

Traditional noble metal oxide, such as RuO2, is considered a benchmark catalyst for acidic oxygen evolution reaction (OER). However, its practical application is limited due to sluggish activity and severe electrochemical corrosion. In this study, Ru‐Fe nanoparticles loading on carbon felt (RuFe@CF) is synthesized via an ultrafast Joule heating method as an active and durable OER catalyst in acidic conditions. Remarkably low overpotentials of 188 and 269 mV are achieved at 10 and 100 mA cm−2, respectively, with a robust stability up to 620 h at 10 mA cm−2. When used as an anode in a proton exchange membrane water electrolyzer, the catalyst shows more than 250 h of stability at a water‐splitting current of 200 mA cm−2. Experimental characterizations reveal the presence of a Ru‐based oxide nanosheath on the surface of the catalyst during OER tests, suggesting a surface reconstruction process that enhances the intrinsic activity and inhibits continuous metal dissolution. Moreover, density functional theory calculations demonstrate that the introduction of Fe into the RuFe@CF catalyst reduces the energy barrier and boosts its activities. This work offers an effective and universal strategy for the development of highly efficient and stable catalysts for acidic water splitting.
A Boron, Nitrogen, and Oxygen Doped π‐Extended Helical Pure Blue Multiresonant Thermally Activated Delayed Fluorescent Emitter for Organic Light Emitting Diodes That Shows Fast kRISC Without the Use of Heavy Atoms
Authors: Weerasinghe Rangani Wathsala , Madayanad Suresh Subeesh , Hall David , Matulaitis Tomas , Slawin Alexandra M. Z. , Warriner Stuart , Lee Yi‐Ting , Chan Chin‐Yiu , Tsuchiya Youichi , Zysman‐Colman Eli , Adachi Chihaya
Published: April 2024

Narrowband emissive multiresonant thermally activated delayed fluorescence (MR‐TADF) emitters are a promising solution to achieve the current industry‐targeted color standard, Rec. BT.2020‐2, for blue color without using optical filters, aiming for high‐efficiency organic light‐emitting diodes (OLEDs). However, their long triplet lifetimes, largely affected by their slow reverse intersystem crossing rates, adversely affect device stability. In this study, a helical MR‐TADF emitter (f‐DOABNA) is designed and synthesized. Owing to its π‐delocalized structure, f‐DOABNA possesses a small singlet‐triplet gap, ΔEST, and displays simultaneously an exceptionally faster reverse intersystem crossing rate constant, kRISC, of up to 2 × 106 s−1 and a very high photoluminescence quantum yield, ΦPL, of over 90% in both solution and doped films. The OLED with f‐DOABNA as the emitter achieved a narrow deep‐blue emission at 445 nm (full width at half‐maximum of 24 nm) associated with Commission Internationale de l'Éclairage (CIE) coordinates of (0.150, 0.041), and showed a high maximum external quantum efficiency, EQEmax, of ≈20%.