bluuebunny/crossref_metadata_2025 huggingface dataset:
A Small Subset of Signal Peptidase Residues are Perturbed by Signal Peptide Binding
Authors: Musial‐Siwek Monika , Yeagle Philip L. , Kendall Debra A.
Published: July 2008

Perturbations of the chemical shifts of a small subset of residues in the catalytically active domain of Escherichia coli signal peptidase I (SPase I) upon binding signal peptide suggest the contact surface on the enzyme for the substrate. SPase I, an integral membrane protein, is vital to preprotein transport in prokaryotic and eukaryotic secretory systems; it binds and proteolyses the N‐terminal signal peptide of the preprotein, permitting folding and localization of the mature protein. Employing isotopically labeled C‐terminal E. coli SPase I Δ2‐75 and an unlabeled soluble synthetic alkaline phosphatase signal peptide, SPase I Δ2‐75 was titrated with the signal peptide and 2D 1H‐15N heteronuclear single‐quantum correlation nuclear magnetic resonance spectra revealed chemical shifts of specific enzyme residues sensitive to substrate binding. These residues were identified by 3D HNCACB, 3D CBCA(CO)NH, and 3D HN(CO) experiments. Residues Ile80, Glu82, Gln85, Ile86, Ser88, Gly89, Ser90, Met91, Leu95, Ile101, Gly109, Val132, Lys134, Asp142, Ile144, Lys145, and Thr234, alter conformation and are likely all in, or adjacent to, the substrate binding site. The remainder of the enzyme structure is unperturbed. Ramifications for conformational changes for substrate docking and catalysis are discussed.
Novel Peptide Ligands of RGS4 from a Focused One‐Bead, One‐Compound Library
Authors: Roof Rebecca A. , Sobczyk‐Kojiro Katarzyna , Turbiak Anjanette J. , Roman David L. , Pogozheva Irina D. , Blazer Levi L. , Neubig Richard R. , Mosberg Henry I.
Published: July 2008

Regulators of G protein signaling accelerate GTP hydrolysis by Gα subunits and profoundly inhibit signaling by G protein‐coupled receptors. The distinct expression patterns and pathophysiologic regulation of regulators of G protein signaling proteins suggest that inhibitors may have therapeutic potential. We previously reported the design, mechanistic evaluation, and structure–activity relationships of a disulfide‐containing cyclic peptide inhibitor of RGS4,YJ34(Ac‐Val‐Lys‐c[Cys‐Thr‐Gly‐Ile‐Cys]‐Glu‐NH2, S‐S) (Roofet al., Chem Biol Drug Des, 67, 2006, 266). Using a focused one‐bead, one‐compound peptide library that contains features known to be necessary for the activity ofYJ34, we now identify peptides that bind to RGS4. Six peptides showed confirmed binding to RGS4 by flow cytometry. Two analogs of peptide2(Gly‐Thr‐c[Cys‐Phe‐Gly‐Thr‐Cys]‐Trp‐NH2, S‐S with a free or acetylatedN‐terminus) inhibited RGS4‐stimulated GαoGTPase activity at 25–50 μm. They selectively inhibit RGS4 but not RGS7, RGS16, and RGS19. Their inhibition of RGS4 does not depend on cysteine‐modification of RGS4, as they do not lose activity when all cysteines are removed from RGS4. Peptide2has been modeled to fit in the same binding pocket predicted forYJ34but in the reverse orientation.
Probing Trypanosoma brucei Glycosylphosphatidylinositol Biosynthesis Using Novel Precursor‐Analogues
Authors: Urbaniak Michael D. , Crossman Arthur , Ferguson Michael A. J.
Published: July 2008

Glycosylphosphatidylinositol precursor‐analogues were synthesized in which the natural diacylglycerol lipid was replaced with either of two steroidal moieties. The ability of the steroidal glycosylphosphatidylinositol precursor‐analogues to prime the glycosylphosphatidylinositol biosynthetic pathway was assessed in a trypanosomal cell‐free system. The N‐acetyl‐d‐glucosaminylphosphatidylinositol de‐N‐acetylase was only able to act upon the N‐acetylglucosamine form of one of the two analogues. However, the glucosamine form of both analogues could be mannosylated, but neither were inositol‐acylated nor modified with ethanolamine phosphate. The use of alternative groups, such as sterols, in place of the natural diacylglycerol lipid may enable the production of more drug‐like, substrate‐based inhibitors.
A preliminary pressure–impact analysis applied in the Pinios river basin (Thessaly, Central Greece)
Authors: Ioannou Alexis , Chatzinikolaou Yorgos , Lazaridou Maria
Published: July 2008

Greece has not yet undertaken one of the first and most important tasks required by the Water Framework Directive (WFD: the integrated review of the impact of human activity on the status of surface waters for each river basin – the IMPRESS analysis. Owing to the lack of a national methodology, a preliminary analysis was carried out for the Pinios river basin, applying a combination of different methodologies refined to suit the particularities of the Greek freshwater environment and to accommodate the limited availability of data. Pressures caused by the main pollution sources, point and nonpoint, were quantified in terms of pollution loads with the use of emission factors. The existing limited biological and physicochemical monitoring data were used to assess impacts. Additionally, we identified pressures caused by alterations from land‐use data; we carried out a River Habitat Survey (RHS) and estimated the hydromorphological impacts through the calculation of a Habitat Modification Score (HMS). Our results suggest that the probability of the Pinios river basin failing to achieve good ecological quality by 2015 due to pollution is high, and due to hydromorphological pressures is moderate.
Gene Expression Profiles of Meningiomas are Associated with Tumor Cytogenetics and Patient Outcome
Authors: Tabernero Maria Dolores , Maillo Angel , Gil‐Bellosta Carlos J. , Castrillo Abel , Sousa Pablo , Merino Marta , Orfao Alberto
Published: July 2008

Cytogenetic analysis is a powerful tool for predicting recurrence in meningiomas, even among histologically benign/grade I tumors. Despite this, no study has been reported in which the impact of tumor cytogenetics on the gene expression profiles (GEP) has been analyzed in meningiomas. Here, we analyzed the GEP of 47 tumors and correlated them with the most clinical relevant cytogenetic subgroups of meningiomas, as confirmed through the analysis of 172 patients. Additionally three normal meningeal samples were also studied.

Overall, our results show a clear association between the clinically relevant cytogenetic subgroups of meningiomas including diploid tumors (n = 18), isolated −22/22q− (n = 12), del(1p36) alone (n = 4) and complex karyotypes associated with del(1p36) and/or −14q (n = 13) and their GEP. Accordingly, based on the expression of 85 genes (40 of which were coded in the altered chromosomes used for patient stratification) the cytogenetic class of the tumor could be predicted with an error of <1%, a clear association being found between the GEP and patient outcome (P = 0.03) but not tumor histopathology.

In summary, we show a clear association between GEP of neoplastic cells and clinically relevant cytogenetic subgroups of meningiomas.
Storability of Antimicrobial Chitosan‐Lysozyme Composite Coating and Film‐Forming Solutions
Authors: Duan J. , Kim K. , Daeschel M.A. , Zhao Y.
Published: July 2008

ABSTRACT:  Chitosan‐lysozyme (CL) film and coating solutions were prepared aseptically by incorporating 60% lysozyme (w/w chitosan) into 3% chitosan solution. The solutions were stored at 10, 21, and 37 °C up to 6 mo for monthly evaluation of physicochemical and antimicrobial properties. Solutions were made into films at each sampling time to investigate lysozyme release, water solubility, water vapor permeability (WVP), tensile strength (TS), and elongation (EL) of the films. During the 6‐mo storage, the pH and translucency of CL solutions did not change (P > 0.05) and microorganisms were not detected with total aerobic count media. CL solutions became darker, with a more saturated yellow hue developing with increased storage time and temperature. Storage enhanced the antimicrobial activities of the solutions against E. coli and L. monocytogenes, and films made of solutions stored at 37 °C exhibited higher antimicrobial activities against these 2 pathogens than those stored at 10 and 21 °C. Increased water solubility and lysozyme release and decreased TS and EL were observed in films made from solutions stored at 37 °C. WVP was not significantly affected by storage temperature and time. These changes might be attributed to increased chitosan degradation by lysozyme hydrolysis at a higher storage temperature and longer storage time. Results indicated that with storage at 10 to 20 °C, premade CL solutions are stable and may be distributed as a commercial product for coating or film applications or both in different foods for at least 6 mo.
Cold Smoking of Atlantic Salmon (Salmo salar) Fillets with Smoke Condensate—an Alternative Processing Technology for the Production of Smoked Salmon
Authors: Birkeland S. , Skåra T.
Published: July 2008

ABSTRACT:  Two different protocols for the production of cold smoked salmon were investigated. All fillets were dry salted (18 h, 4 °C) before being allotted to a smoke condensate/liquid smoke protocol (SCP), which included drenching (1 min) in smoke condensate [1:3 (v/v) smoke:water] and drying (150 min, 28.4 ± 2.2 °C) or a wood chips protocol (WCP) that included drying and smoking in a regular smoking chamber (23 °C, 480 min) using wood chips for smoke production. Quality assessments were performed on the smoked fillets at day 0 and after 7, 14, and 31 d of storage (3.4 ± 0.7 °C). Application of the SCP resulted in a significantly higher (P < 0.01) processing yield (89.6%± 0.7%) as compared to the WCP (88.6%± 0.5%). On day 0, the SCP fillets were significantly (P < 0.01) less light (L*) and yellow (b*) and had a lower chroma (C*) and hue (h*) compared to the fillets processed with WCP. From 7 d until the end of storage time, small differences in color were observed. After 31 d of storage, the SCP fillets had a significantly higher (P < 0.05) intensity of oily texture and lower intensity of salty and smoke taste. Texture profile analysis (TPA) showed few significant differences between the processing protocols, although the WCP fillets were significantly harder than the SCP fillets when recording the force at 60% compression of the fillet height. The use of smoke condensate and drenching technology is a way of producing cold smoked salmon with quality characteristics quite similar to those found in commercial “traditional” products, although processors who want to use this technology have to optimize the drying step and the smoke condensate formulation to their specifications.
Aroma‐Active Components ofLycii fructus(kukija)
Authors: Lee G.‐H. , Shin Y. , Oh M.‐J.
Published: July 2008

ABSTRACT: The fruit ofLycii fructushas been used as a tonic medicine and a long‐term healthy food without side effect in Asia. An increase in the demand for natural healthy food,L. fructushas been thought as a source of healthy foods. For its value adding, its character impact aromas were isolated by using direct solvent extraction with vacuum transfer and identified by using gas chromatography olfactometry (GC‐O) and GC‐mass spectrometry (GC‐MS). Thirty‐three odor compounds were sniffed at GC‐O, each trial equipped with DB‐5MS and HP‐WAX capillary column. The most contributing odor compounds inL. fructuswere (E)‐2‐heptenal (green, mushroomy), 1‐heptanol (planty, oily), hexanal (planty), 3‐octanol (mushroomy, planty), 1‐octen‐3‐ol (mushroomy), and 2‐methyl‐2‐butenoic acid (pungent, planty), which might be produced by enzymatic oxidation and/or oxidation of lipids and carotenes, resulting in undesirable aromas.
Processing and Storage Effects on Monomeric Anthocyanins, Percent Polymeric Color, and Antioxidant Capacity of Processed Black Raspberry Products
Authors: Hager A. , Howard L.R. , Prior R.L. , Brownmiller C.
Published: July 2008

ABSTRACT:  This study evaluated the effects of processing and 6 mo of storage on total monomeric anthocyanins, percent polymeric color, and antioxidant capacity of black raspberries that were individually quick‐frozen (IQF), canned‐in‐syrup, canned‐in‐water, pureed, and juiced (clarified and nonclarified). Total monomeric anthocyanins, percent polymeric color, and ORACFL were determined 1 d postprocessing and after 1, 3, and 6 mo of storage. Thermal processing resulted in marked losses in total anthocyanins ranging from 37% in puree to 69% to 73% in nonclarified and clarified juices, respectively, but only the juices showed substantial losses (38% to 41%) in ORACFL. Storage at 25 °C of all thermally processed products resulted in dramatic losses in total anthocyanins ranging from 49% in canned‐in‐syrup to 75% in clarified juices. This coincided with marked increases in percent polymeric color values of these products over the 6‐mo storage. ORACFL values showed little change during storage, indicating that the formation of polymers compensated for the loss of antioxidant capacity due to anthocyanin degradation. Total anthocyanins and ORACFL of IQF berries were well retained during long‐term storage at –20 °C.
Fruit Quality, Antioxidant Contents and Activity, and Antiproliferative Activity of Strawberry Fruit Stored in Elevated CO2 Atmospheres
Authors: Shin Y. , Ryu J.A. , Liu R.H. , Nock J.F. , Polar‐Cabrera K. , Watkins C.B.
Published: July 2008

ABSTRACT:  The effects of CO2 in the storage atmosphere on color, firmness, ascorbic acid (AA), anthocyanins, flavonoids, phenolics, total antioxidant activity, and antiproliferative activity of strawberry fruit have been investigated. “Northeaster” and “Earliglow” strawberries were stored in air or in 20% CO2 (in air) at 3 °C for 20 d. Color changes in Northeaster were delayed more by CO2 treatment than in Earliglow. Firmness of CO2‐stored fruit increased slightly compared with those stored in air. The increases in total and reduced AA concentrations during air storage were usually prevented by CO2 storage in both cultivars. Dehydroascorbic acid (DHA) concentrations increased during CO2 storage. Anthocyanins and flavonoids, and total antioxidant activity of both cultivars were higher in air‐stored fruit than in CO2‐stored fruit. The total phenolic concentration was lower in CO2‐stored Earliglow fruit than in air, but storage treatment did not affect that of Northeaster. A 40 mg/mL concentration of Northeaster strawberry extract inhibited about 80% of HepG2 human liver cancer cell proliferation. CO2 treatment did not affect the antiproliferative activity of strawberry fruits, but antiproliferative activity was greater at harvest than after storage.
Comparative analysis of G‐CSFR and GM‐CSFR expressions on CD34+ cells in patients with aplastic anemia and myelodysplastic syndrome
Authors: XU H. , LI A. , YU Y. , LI J. , LIU X. , WANG X. , WANG X. , XU G.
Published: July 2008

The aim of this article was to explore the pathogenetic differences, as well as to provide a new way for the differential diagnosis of these two diseases by comparative analysis of CD34+ cells numbers and their surface expression of granulocyte colony‐stimulating factor receptor (G‐CSFR) and granulocyte‐macrophage colony‐stimulating factor receptor (GM‐CSFR) in patients with aplastic anemia (AA) and myelodysplastic syndrome (MDS). Twenty‐seven patients with AA, 45 patients with MDS, and 20 normal controls were enrolled in this study. The ratio of CD34+ cells and their surface expression of G‐CSFR and GM‐CSFR were detected by flow cytometry (FCM). The ratio of CD34+ cells in BMMNC of AA, MDS patients and controls were 0.2438 ± 0.1129%, 2.1677 ± 1.1345% and 1.0792 ± 0.3221%, respectively. Compared with normal controls as well as MDS patients, the ratio of CD34+ cells in BMMNC of AA was significantly reduced (P < 0.05). The ratio of CD34+ cells in MDS was significantly elevated than controls (P < 0.05). The ratio of CD34+ cells in BMMNC of MDS‐RA and MDS‐RAEB patients were 1.2821 ± 0.4658% and 3.7729 ± 2.3360%, respectively. Compared with normal controls and MDS‐RA patients, the ratio of CD34+ cells in MDS‐RAEB was significantly elevated (P < 0.05). The ratio of CD34+ cells in MDS‐RA was significantly elevated than AA patients (P < 0.05). The surface expression of G‐CSFR on CD34+ cells of AA, MDS patients and controls were 34.402 ± 21.8357%, 26.376 ± 15.2895% and 21.443 ± 7.4465%, respectively. The surface expression of G‐CSFR on CD34+ cells of MDS‐RA and MDS‐RAEB patients were 22.788 ± 14.7628% and 30.682 ± 15.5346%. The surface expression of GM‐CSFR on CD34+ cells of AA, MDS patients and controls were 6.5961 ± 4.4322%, 18.2737 ± 10.9841% and 4.2753 ± 2.6249%, respectively. Compared with AA and controls, the expression of GM‐CSFR in MDS patients was significantly elevated (P < 0.05). The surface expression of GM‐CSFR on CD34+ cells of MDS‐RA and MDS‐RAEB patients were 16.1625 ± 6.9487% and 22.1003 ± 14.2983%. In AA patients, the ratio of CD34+ cells in BMMNC less than 0.1% accounts for 75% (6/8) SAA patients, compared with 10.55% (2/19) in CAA (P < 0.05). The detection of CD34+ cells and their surface expression of granulocyte (macrophage) colony‐stimulating factor receptors G (M)‐CSFR in AA and MDS are helpful in the differential diagnosis or prognosis of these two disorders.
The IPO Derby: Are There Consistent Losers and Winners on This Track?
Authors: Chan Konan , Cooney John W. , Kim Joonghyuk , Singh Ajai K.
Published: July 2008

We examine the individual and joint relation of discretionary accounting accruals, underwriter reputation, and venture capital backing with the long‐run performance of initial public offerings (IPOs). We find that although correlated to some extent, these variables do not manifest the same underlying phenomena in their relation to IPOs' performance. The confluence of the variables is more important than using any one of them individually to identify IPOs that exhibit abnormal long‐run stock returns. The combination of their negative aspects helps identify extreme underperformers. We also identify a set of winner IPOs by combining the positive aspects of the three variables.
The Impact of Firm Location on Equity Issuance
Authors: Loughran Tim
Published: July 2008

In this paper, I use location as a proxy for the ability of a firm to issue equity. Numerous studies indicate that investors are better able to obtain information on nearby companies. I posit that costs in generating information will be higher for rural firms with few investors in their proximity, than for urban firms with many nearby investors. As predicted, I find that rural firms are less likely to conduct seasoned equity offerings than firms located in urban areas. Furthermore, I find that when a rural firm issues equity, it uses a lower‐quality underwriter than otherwise similar urban firms.
Moving from Private to Public Ownership: Selling Out to Public Firms versus Initial Public Offerings
Authors: Poulsen Annette B. , Stegemoller Mike
Published: July 2008

We study two alternative means to move assets from private to public ownership: through the acquisition of private companies by firms that are public (sellouts) or through initial public share offerings (IPOs). We consider firm‐specific characteristics for 1,074 IPO and 735 sellout firms to identify differences in growth, capital constraints, and asymmetric information between the two types of transactions. Our results suggest that firms move to public ownership through an IPO when they have greater growth opportunities and face more capital constraints. We provide a better understanding of the firm‐specific characteristics that lead firms to go public.
An Empirical Analysis of the Stockholder‐Bondholder Conflict in Corporate Spin‐Offs
Authors: Veld Chris , Veld‐Merkoulova Yulia V.
Published: July 2008

We analyze the effect of daily stock and bond abnormal returns around spin‐off announcements. Over a three‐day event window, we find statistically significant abnormal returns of 3.07% for stocks and 0.11% for straight bonds. Both stock and bond abnormal returns are higher for firms with lower interest and dividend payouts. Stock abnormal returns are also higher for firms with higher pre‐spin‐off leverage. Overall, we find that the firm value increase compensates for the wealth transfer effect and that bondholders' wealth is not reduced as a result of spin‐off.
Process Intensification in a “Simulated Moving-Bed” Heat Regenerator
Authors: Murthy D. S. , Sivakumar S. V. , Kant Keshav , Rao D. P.
Published: July 2008

The solid-gas contacting for thermal storage and thermal recovery is generally carried out in fixed-bed regenerators. Compared to a fixed bed, higher thermal recovery can be achieved in a moving bed with countercurrent flow of gas and solids. However, the moving beds have not been widely used due to difficulties in solid handling. The relative movement of the bed to the gas flow can be simulated in a fixed bed by moving the inlet and outlet ports of the gas along the length of the bed. Similar simulated moving beds are already in use for adsorptive separation of liquid mixtures in chemical industries. A novel moving-port system is proposed to achieve simulated moving-bed operation in a fixed bed. We have carried out studies to evaluate the relative performance of the fixed and the simulated moving-bed heat regenerators. We have examined the feasibility of replacing a set of three blast furnaces and thermal regeneration of an adsorption bed with the simulated moving-bed regenerator. It is found that high-heat transfer intensification can be achieved. The results indicate that three blast-furnace stoves can be replaced by a simulated moving-bed regenerator of volume of about 100 times smaller than the stoves. The heat-transfer intensification is high enough to carry out thermal regeneration of the adsorption beds in a cycle time that is in the range of the pressure swing adsorption, which is favored for its faster rate of regeneration.
Simplified Two-Dimensional Analytical Model for Friction Stir Welding Heat Transfer
Authors: Perivilli Satish , Peddieson John , Cui Jie
Published: July 2008

A two-dimensional heat transfer problem pertaining to friction stir welding is developed by converting various pin tool configurations of interest to a simplified pin only configuration by assigning an equivalent heat flux to the pin surface. Mechanical dissipation heating, responsible for the welding, is modeled by means of a thermal boundary condition at the pin surface. A series solution is developed for the temperature distributions in the workpiece (assumed to be infinite) and these distributions are analyzed at various radial and circumferential locations. It is found that the closed form solutions developed are not influenced greatly by the truncation numbers of this series. Maximum reduced temperatures pertinent to configurations available in literature are estimated from the series and one term solutions developed and compared with those observed. Furthermore, the applicability of one term solution of this series is tested for various parametric combinations based on models available in literature. It is found that the one term solution can be applied to within a reasonable range of the process governing parameters.
The Solid-State Neck Growth Mechanisms in Low Energy Laser Sintering of Gold Nanoparticles: A Molecular Dynamics Simulation Study
Authors: Pan Heng , Ko Seung H. , Grigoropoulos Costas P.
Published: July 2008

Molecular dynamics (MD) simulations were employed to investigate the mechanism and kinetics of the solid-state sintering of two crystalline gold nanoparticles (4.4–10.0nm) induced by low energy laser heating. At low temperature (300K), sintering can occur between two bare nanoparticles by elastic and plastic deformation driven by strong local potential gradients. This initial neck growth occurs very fast (<150ps), and is therefore essentially insensitive to laser irradiation. This paper focuses on the subsequent longer time scale intermediate neck growth process induced by laser heating. The classical diffusion based neck growth model is modified to predict the time resolved neck growth during continuous heating with the diffusion coefficients and surface tension extracted from MD simulation. The diffusion model underestimates the neck growth rate for smaller particles (5.4nm) while satisfactory agreement is obtained for larger particles (10nm). The deviation is due to the ultrafine size effect for particles below 10nm. Various possible mechanisms were identified and discussed.
Vertical Free Convective Boundary-Layer Flow in a Bidisperse Porous Medium
Authors: Rees D. A. S. , Nield D. A. , Kuznetsov A. V.
Published: July 2008

In this article, we study the effect of adopting a two-temperature and two-velocity model, appropriate to a bidisperse porous medium (BDPM), on the classical Cheng–Minkowycz study of vertical free convection boundary-layer flow in a porous medium. It is shown that the boundary-layer equations can be expressed in terms of three parameters: a modified volume fraction, a modified thermal conductivity ratio, and a third parameter incorporating both thermal and BDPM properties. A numerical simulation of the developing boundary layer is guided by a near-leading-edge analysis and supplemented by a far-field analysis. The study is completed by a presentation of numerical simulations of the elliptic equations in order to determine how the adoption of the BDPM model affects the thermal fields in the close vicinity of the origin.
An Analytical Model of External Streaming and Heat Transfer for a Levitated Flattened Liquid Drop
Authors: Lee Sungho , Sadhal S. S. , Rednikov Alexei Ye.
Published: July 2008

We present here the heat-transfer and fluid flow analysis of an acoustically levitated flattened disk-shaped liquid drop. The interest in this work arises from the noncontact measurement of the thermophysical properties of liquids. Such techniques have application to liquids in the undercooled state, i.e., the situation when a liquid stays in a fluidic state even when the temperature falls below the normal freezing point. This can happen when, for example, a liquid sample is held in a levitated state. Since such states are easily disrupted by measurement probes, noncontact methods are needed. We have employed a technique involving the use of acoustically levitated samples of the liquid. A thermal stimulus in the form of laser heating causes thermocapillary motion with flow characteristics depending on the thermophysical properties of the liquid. In a gravity field, buoyancy is disruptive to this thermocapillary flow, masking it with the dominant natural convection. As one approach to minimizing the effects of buoyancy, the drop was flattened (by intense acoustic pressure) in the form of a horizontal disk, about 0.5mm thick. As a result, with very little gravitational potential, and with most of the buoyant flow suppressed, thermocapillary flow remained the dominant form of fluid motion within the drop. This flow field is visualizable and subsequent analysis for the inverse problem of the thermal property can be conducted. This calls for numerical calculations involving a heat-transfer model for the flattened drop. With the presence of an acoustic field, the heat-transfer analysis requires information about the corresponding Biot number. In the presence of a high-frequency acoustic field, the steady streaming originates in a thin shear-wave layer, known as the Stokes layer, at a surface of the drop. The streaming develops into the main fluid, and is referred to as the outer streaming. Since the Stokes layer is asymptotically thin in comparison to the length scale of the problem, the outer streaming can be formally described by an effective slip velocity at the boundary. The presence of the thin Stokes layer, and the slip condition at the interface, changes the character of the heat-transfer mechanism, which is inherently different from the traditional boundary layer. The current analysis consists of a detailed semianalytical calculation of the flow field and the heat-transfer characteristics of a levitated drop in the presence of an acoustic field.
Thermal Contact Calibration Between a Thermocouple Probe and a Microhotplate
Authors: Thiery L. , Toullier S. , Teyssieux D. , Briand D.
Published: July 2008

Since local thermal probing has become a major tool for studying transport phenomena at micro- and nanoscale levels, the fundamental aspect of the interaction between the tip of the probe and the sample has remained the key point on which any quantitative measurement relies. In this paper, we present results on thermal resistances involved in the contact mechanism of a microthermocouple cantilever probe that is used to scan the surface of a microhotplate at different levels of temperature. We point out the potential of such an active microsystem as an efficient calibration tool for near-field thermal probes.
Artificial Neural Networks (ANNs): A New Paradigm for Thermal Science and Engineering
Authors: Yang Kwang-Tzu
Published: July 2008

The use of artificial neural network (ANN), as one of the artificial intelligence methodologies, in a variety of real-world applications has been around for some time. However, the application of ANN to thermal science and engineering is still relatively new, but is receiving ever-increasing attention in recent published literature. Such attention is due essentially to special requirement and needs of the field of thermal science and engineering in terms of its increasing complexity and the recognition that it is not always feasible to deal with many critical problems in this field by the use of traditional analysis. The purpose of the present review is to point out the recent advances in ANN and its successes in dealing with a variety of important thermal problems. Some current ANN shortcomings, the development of recent advances in ANN-based hybrid analysis, and its future prospects will also be indicated.
Power Law Velocity and Temperature Profiles in a Fully Developed
Turbulent Channel Flow
Authors: Seena Abu , Afzal Noor
Published: July 2008

The power law temperature distribution in a fully developed turbulent channel flow for large Peclet numbers has been proposed in the present work. The analysis of the power law velocity profile in a fully developed mean turbulent channel flow would be used for carrying out the analysis of the power law temperature profile. The Reynolds mean thermal energy equation in a fully developed mean turbulent channel flow has been analyzed. The mean turbulent thermal flow is divided in the inner and outer thermal layers that have been matched by Izakson–Millikan–Kolmogorov hypothesis to get the power law temperature profiles and the power law heat transfer law in the overlap region, in addition to traditional log laws for temperature profiles and heat transfer. It has been shown that the envelope of the heat transfer power law gives the heat transfer log law. Further, it is shown that the temperature power law index and prefactor are functions of the friction Peclet number, as well as function of an alternate variable, the nondimensional friction temperature. It is shown that for large Peclet numbers the power law temperature profile is equivalent to the log law temperature profile. The direct numerical simulation velocity profile data of fully developed turbulent flow provide good support for the power law temperature profile theory.
Logarithmic Expansions for Reynolds Shear Stress and Reynolds Heat Flux in a Turbulent Channel Flow
Authors: Seena Abu , Bushra A. , Afzal Noor
Published: July 2008

The heat and fluid flow in a fully developed turbulent channel flow have been investigated. The closure model of Reynolds shear stress and Reynolds heat flux as a function of a series of logarithmic functions in the mesolayer variable have been adopted. The interaction between inner and outer layers in the mesolayer (intermediate layer) arising from the balance of viscous effect, pressure gradient and Reynolds shear stress (containing the maxima of Reynolds shear stress) was first proposed by Afzal (1982, “Fully Developed Turbulent Flow in a Pipe: An Intermediate Layer,” Arch. Appl. Mech., 53, 355–377). The unknown constants in the closure models for Reynolds shear stress and Reynolds heat flux have been estimated from the prescribed boundary conditions near the axis and surface of channel. The predictions are compared with the DNS data Iwamoto et al. and Abe et al. for Reynolds shear stress and velocity profile and Abe et al. data of Reynolds heat flux and temperature profile. The limitations of the closure models are presented.
Ventilation
of Wind-Permeable Clothed Cylinder Subject to Periodic Swinging Motion: Modeling and
Experimentation
Authors: Ghaddar N. , Ghali K. , Jreije B.
Published: July 2008

A theoretical and experimental study has been performed to determine the ventilation induced by swinging motion and external wind for a fabric-covered cylinder of finite length representing a limb. The estimated ventilation rates are important in determining local thermal comfort. A model is developed to estimate the external pressure distribution resulting from the relative wind around the swinging clothed cylinder. A mass balance equation of the microclimate air layer is reduced to a pressure equation assuming laminar flow in axial and angular directions and that the air layer is lumped in the radial direction. The ventilation model predicts the total renewal rate during the swinging cycle. A good agreement was found between the predicted ventilation rates at swinging frequencies between 40rpm and 60rpm and measured values from experiments conducted in a controlled environmental chamber (air velocity is less than 0.05m∕s) and in a low speed wind tunnel (for air speed between 2m∕s and 6m∕s) using the tracer gas method to measure the total ventilation rate induced by the swinging motion of a cylinder covered with a cotton fabric for both closed and open aperture cases. A parametric study using the current model is performed on a cotton fabric to study the effect of wind on ventilation rates for a nonmoving clothed limb at wind speeds ranging from 0.5m∕sto8m∕s, the effect of a swinging limb in stagnant air at frequencies up to 80rpm, and the combined effect of wind and swinging motion on the ventilation rate. For a nonmoving limb, ventilation rate increases with external wind. In the absence of wind, the ventilation rate increases with increased swinging frequency.
Thin Film Phonon Heat Conduction by the Dispersion Lattice Boltzmann Method
Authors: Escobar Rodrigo A. , Amon Cristina H.
Published: July 2008

Numerical simulations of time-dependent thermal energy transport in semiconductor thin films are performed using the lattice Boltzmann method applied to phonon transport. The discrete lattice Boltzmann Method is derived from the continuous Boltzmann transport equation assuming nonlinear, frequency-dependent phonon dispersion for acoustic and optical phonons. Results indicate that the heat conduction in silicon thin films displays a transition from diffusive to ballistic energy transport as the characteristic length of the system becomes comparable to the phonon mean free path and that the thermal energy transport process is characterized by the propagation of multiple superimposed phonon waves. The methodology is used to characterize the time-dependent temperature profiles inside films of decreasing thickness. Thickness-dependent thermal conductivity values are computed based on steady-state temperature distributions obtained from the numerical models. It is found that reducing feature size into the subcontinuum regime decreases thermal conductivity when compared to bulk values, at a higher rate than what was displayed by the Debye-based gray lattice Boltzmann method.
Extreme Plane Wall Midplane Temperatures Due to Sequential Heating and Cooling
Authors: Bergman T. L.
Published: July 2008

The thermal response of a one-dimensional plane wall to sequential heating and cooling is considered. Of interest is the thermal response at the midplane of the wall in terms of the extreme temperatures that evolve after heating subsides. Correlations are generated to estimate the extreme temperatures and the times at which they occur.
Experimental Study of Heat Conduction in Aqueous Suspensions of Aluminum Oxide Nanoparticles
Authors: Ju Y. Sungtaek , Kim Jichul , Hung Ming-Tsung
Published: July 2008

We report measurements of the thermal conductivity of aqueous suspensions of aluminum oxide nanoparticles with nominal diameters of 20nm, 30nm, and 45nm and at volume concentrations up to 10%. Potential complications in the pulsed transient hot-wire technique for characterizing nanofluids are examined, which motivate the development of a microhot strip setup with a small thermal time constant. The average particle size is monitored for samples subjected to different durations of sonication and the thermal conductivity is determined at two different temperatures for each of the samples. The present data do not reveal any anomalous enhancement in the thermal conductivity previously reported for comparable nanofluids. The concentration dependence of the thermal conductivity can be explained using the conventional effective medium model with a physically reasonable set of parameters.
The Effect of a Transition Layer Between a Fluid and a Porous Medium: Forced Convection in a Channel
Authors: Kuznetsov A. V. , Nield D. A.
Published: July 2008

Flow in a three-layer channel is modeled analytically. The channel consists of a transition layer sandwiched between a porous medium and a fluid clear of solid material. Within the transition layer, the reciprocal of the permeability varies linearly across the channel. The Brinkman model is used for the momentum equations for the porous medium layer and the transition layer. The velocity profile is obtained in closed form in terms of Airy, exponential, and polynomial functions and this is employed to find analytically the Nusselt number for fully developed forced convection with boundaries subject to uniform and constant heat flux.
Modeling of the Adsorption Kinetics and the Convection of Surfactants in a Weld Pool
Authors: Do-Quang Minh , Amberg Gustav , Pettersson Claes-Ove
Published: July 2008

This paper presents a comprehensive three-dimensional, time-dependent model for simulating the adsorption kinetics and the redistribution of surfactants at the surface and in the bulk of a weld pool. A physicochemical approach that was included in this paper allows the surfactant concentration at the surface and in the bulk to depart from its thermodynamical equilibrium. The Langmuir equilibrium adsorption ratio was based on the kseg coefficient of Sahoo et al. (1988, “Surface-Tension of Binary Metal—Surface-Active Solute Systems Under Conditions Relevant to Welding Metallurgy,” Metall. Trans. B, 19B, pp. 483–491) and was finally used for calculating fluid flow and heat transfer in gas tungsten arc welding of a super duplex stainless steel, SAF 2507. In this study, the authors applied the multicomponent surfactant mass transfer model to investigate the effect of the influence of sulfur and oxygen redistribution in welding of a super duplex stainless steel.
Laminar Forced Convection for Flow Across a Cylinder With Longitudinal Fins of Finite Thickness
Authors: Haldar S. C. , Kochhar G. S. , Manohar K.
Published: July 2008

Conjugate numerical solution of laminar forced convection for cross-flow over a cylinder with external longitudinal fins of finite thickness has been carried out. The rate of heat transfer from the fins increases and that from the free area of the cylinder marginally decreases with an increase in thickness, length, and number of fins. The rate of heat transfer from the fins alone is usually much higher than that from the cylinder surface. As a consequence, the net result of these two opposing effects is an increase in the total heat transfer over that of the smooth cylinder, the amount increasing with an increase in thickness, length, and number of fins but with diminishing returns. The fins are more effective at high Re values than at low ones.
Lack of a Significant Drug Interaction between Raltegravir and Tenofovir
Authors: Wenning Larissa A. , Friedman Evan J. , Kost James T. , Breidinger Sheila A. , Stek Jon E. , Lasseter Kenneth C. , Gottesdiener Keith M. , Chen Joshua , Teppler Hedy , Wagner John A. , Stone Julie A. , Iwamoto Marian
Published: July 2008

Raltegravir is a novel human immunodeficiency virus type 1 (HIV-1) integrase inhibitor with potent in vitro activity (95% inhibitory concentration of 31 nM in 50% human serum). This article reports the results of an open-label, sequential, three-period study of healthy subjects. Period 1 involved raltegravir at 400 mg twice daily for 4 days, period 2 involved tenofovir disoproxil fumarate (TDF) at 300 mg once daily for 7 days, and period 3 involved raltegravir at 400 mg twice daily plus TDF at 300 mg once daily for 4 days. Pharmacokinetic profiles were also determined in HIV-1-infected patients dosed with raltegravir monotherapy versus raltegravir in combination with TDF and lamivudine. There was no clinically significant effect of TDF on raltegravir. The raltegravir area under the concentration time curve from 0 to 12 h (AUC
0-12
) and peak plasma drug concentration (
C
max
) were modestly increased in healthy subjects (geometric mean ratios [GMRs], 1.49 and 1.64, respectively). There was no substantial effect of TDF on raltegravir concentration at 12 h postdose (
C
12
) in healthy subjects (GMR [TDF plus raltegravir-raltegravir alone], 1.03; 90% confidence interval [CI], 0.73 to 1.45), while a modest increase (GMR, 1.42; 90% CI, 0.89 to 2.28) was seen in HIV-1-infected patients. Raltegravir had no substantial effect on tenofovir pharmacokinetics:
C
24
, AUC, and
C
max
GMRs were 0.87, 0.90, and 0.77, respectively. Coadministration of raltegravir and TDF does not change the pharmacokinetics of either drug to a clinically meaningful degree. Raltegravir and TDF may be coadministered without dose adjustments.
In Vitro Profiling of Ceftaroline against a Collection of Recent Bacterial Clinical Isolates from across the United States
Authors: Ge Yigong , Biek Donald , Talbot George H. , Sahm Daniel F.
Published: July 2008

This study evaluated the in vitro activity of ceftaroline, a novel cephalosporin with broad-spectrum activity against gram-negative and -positive pathogens, against 4,151 recent clinical isolates collected in the United States. Ceftaroline was very potent against bacteria found in community- and hospital-acquired infections, including methicillin-resistant
Staphylococcus aureus
, multidrug-resistant
Streptococcus pneumoniae
, and common
Enterobacteriaceae
spp.
Pharmacokinetics of High-Dose Lopinavir-Ritonavir with and without Saquinavir or Nonnucleoside Reverse Transcriptase Inhibitors in Human Immunodeficiency Virus-Infected Pediatric and Adolescent Patients Previously Treated with Protease Inhibitors
Authors: Robbins Brian L. , Capparelli Edmund V. , Chadwick Ellen G. , Yogev Ram , Serchuck Leslie , Worrell Carol , Smith Mary Elizabeth , Alvero Carmelita , Fenton Terence , Heckman Barbara , Pelton Stephen I. , Aldrovandi Grace , Borkowsky William , Rodman John , Havens Peter L.
Published: July 2008

Human immunodeficiency virus (HIV)-infected children and adolescents who are failing antiretrovirals may have a better virologic response when drug exposures are increased, using higher protease inhibitor doses or ritonavir boosting. We studied the pharmacokinetics and safety of high-dose lopinavir-ritonavir (LPV/r) in treatment-experienced patients, using an LPV/r dose of 400/100 mg/m2orally every 12 h (p.o. q12h) (without nonnucleoside reverse transcriptase inhibitor [NNRTI]), or 480/120 mg/m2p.o. q12h (with NNRTI). We calculated the LPV inhibitory quotient (IQ), and when the IQ was <15, saquinavir (SQV) 750 mg/m2p.o. q12h was added to the regimen. We studied 26 HIV-infected patients. The median age was 15 years (range, 7 to 17), with 11.5 prior antiretroviral medications, 197 CD4 cells/ml, viral load of 75,577 copies/ml, and a 133-fold change in LPV resistance. By treatment week 2, 14 patients had a viral-load decrease of >0.75 log10, with a median maximal decrease in viral load of −1.57 log10copies/ml at week 8. At week 2, 19 subjects showed a median LPV area under the concentration-time curve (AUC) of 157.2 (range, 62.8 to 305.5) μg·h/ml and median LPV trough concentration (Ctrough) of 10.8 (range, 4.1 to 25.3) μg/ml. In 16 subjects with SQV added, the SQV median AUC was 33.7 (range, 4.4 to 76.5) μg·h/ml and the median SQVCtroughwas 2.1 (range, 0.2 to 4.1) μg/ml. At week 24, 18 of 26 (69%) subjects remained in the study. Between weeks 24 and 48, one subject withdrew for nonadherence and nine withdrew for persistently high virus load. In antiretroviral-experienced children and adolescents with HIV, high doses of LPV/r with or without SQV offer safe options for salvage therapy, but the modest virologic response and the challenge of adherence to a regimen with a high pill burden may limit the usefulness of this approach.
Increasing Trends in Antimicrobial Resistance among Clinically Important Anaerobes and
Bacteroides fragilis
Isolates Causing Nosocomial Infections: Emerging Resistance to Carbapenems
Authors: Liu Chia-Ying , Huang Yu-Tsung , Liao Chun-Hsing , Yen Li-Ching , Lin Hsiu-Ying , Hsueh Po-Ren
Published: July 2008

This study reports data on the susceptibilities to five commonly used antianaerobic agents of five clinically frequently encountered anaerobes from 2000 to 2007 and to
Bacteroides fragilis
isolates causing nosocomial infections from 1990 to 2006. There was a trend of decreasing susceptibilities of these anaerobes to ampicillin-sulbactam, cefmetazole, chloramphenicol, and clindamycin with time during the study period. The rates of susceptibility to clindamycin and cefmetazole for all clinical isolates of
Bacteroides fragilis
isolates were higher than those of isolates associated with nosocomial infections. The MICs of 207 anaerobic blood isolates collected in 2006 to 14 antimicrobial agents were determined by the agar dilution method. The rates of nonsusceptibility to imipenem and meropenem were 7% and 12% for
B. fragilis
isolates (
n
= 60), 7% and 3% for
Bacteroides thetaiotamicron
isolates (
n
= 30), 4% and 4% for
Fusobacterium
species (
n
= 27), 6% and 0% for
Prevotella
species (
n
= 16), 15% and 0% for
Clostridium
species (
n
= 28), and 0% and 0% for
Peptostreptococcus
species (
n
= 32). The rates of susceptibility to moxifloxacin were 90% for
B. fragilis
isolates, 87% for
B. thetaiotaomicron
isolates, 81% for
Fusobacterium
species, 75% for
Prevotella
species, 93% for
Clostridium
species, and 78% for
Peptostreptococcus
species. Thirty-six percent of
Clostridium
species and 12% of
Peptostreptococcus
species were not susceptible to metronidazole. Comparison of the data with the data from a previous survey from the same institute in 2002 revealed higher rates of nonsusceptibility to carbapenems, especially for
B. fragilis
,
Fusobacterium
species, and
Prevotella
species isolates. The high rates of nonsusceptibility to commonly used antianaerobic agents mandate our attention, and periodic monitoring of the trend of the resistance is crucial.