bluuebunny/crossref_metadata_2025 huggingface dataset:
Total Temperature Measurement of Turbulent Gas Flow at Microtube Exit
Authors: Hong Chungpyo , Isobe Kyohei , Asako Yutaka , Ueno Ichiro
Published: December 2013

This paper describes experimental results on total temperature measurement to obtain heat transfer characteristics of turbulent gas flow in a microtube with constant wall temperature. The experiments were performed for nitrogen gas flow through a microtube of 354 μm in diameter with 100 mm in length. The wall temperature was maintained at 310 K, 330 K, and 350 K by circulating water around the microtube, respectively. The stagnation pressure was chosen in such a way that the exit Mach number ranges from 0.1 to 1.0. In order to obtain heat transfer rate of turbulent gas flow through a micro-tube, the total temperatures of gas flowing out of a microtube exit were measured with the set of total temperature measurement attached to micro stage with position fine adjustment. The numerical computations based on the Arbitrary - Langrangian - Eulerian (ALE) method were also performed for the turbulent gas flow with the same conditions of the experiments. The results were in excellent agreement.
Numerical Analysis on Heat Transfer Characteristics of Looped Minichannel Using Phase-Change VOF Method
Authors: Onishi Hajime , Kawamura Motoya , Tada Yukio , Takimoto Akira
Published: December 2013

This study develops a numerical simulation of liquid-vapor two phase flows accompanied with the phase change. In the developed simulation, the VOF (Volume of Fluid) method is adopted for tracking the liquid-vapor interface and the temperature recovery method for estimating mass transfer due to the phase change. Firstly, the numerical simulation is performed for film-boiling and film-condensation problems for validating the evaporation (boiling) and condensation calculation. The numerical result for the film-boiling problem is in good agreement with the Berenson’s semi-empirical correlation in terms of the heat transfer coefficient. Moreover, the numerical results for the film-condensation problem are also in good agreement with the theoretical analysis by Nusselt in terms of the film growth rate and the heat transfer coefficient. These have confirmed the reliability of the developed simulation. Then, the developed simulation is applied to investigate the heat transfer characteristics of the heat transport device with a pump-driven looped minichannel. The result reveals a new interesting feature of the minichannel heat device.
Effects of Curved Section on Gas-Liquid Two-Phase Flow in Milli-Channel
Authors: Takeda Kazuki , Okamoto Shinpei , Yoshida Kenji , Kataoka Isao
Published: December 2013

In recent years, we can easily find the gas-liquid two-phase flow in narrow channel which has straight section and curved section in many industrial products. In order to improve the performance of these industrial products, it is important to clarify the effects of curved section on gas-liquid two-phase flow behavior in narrow channel. In this study, we have measured the pressure loss precisely on straight section and curved section in milli-channel respectively. From the measured pressure loss, we evaluated the mean pressure loss and its intensity. Flow visualization by using high-speed video camera was additionally performed to make clear the relation between modification of pressure loss and flow pattern in curved section. As a result, effects of curved section on gas-liquid two-phase flow in narrow channel were evaluated.
Microfluidic Control of Microbeads and Ferrofluid in a Microtube
Authors: Shibata Yuichi , Okamoto Osamu , Kawaji Masahiro
Published: December 2013

The field of microfluidics is developing with advances in MEMS, biotechnology and μ-TAS technologies. In various devices, controlling the flow rate of liquid or gas accurately at micro or nanoliter volume levels is required. By using a ferrofluid, the flow of a liquid or gas in a microchannel can be controlled by the driving power exerted on the ferrofluid. Also alginate microbeads can be applied to a study of transfer technology in a bioreactor and DDS (Drug Delivery System). In this field, production and control of microbeads are required. In the present study, an unsteady flow of a ferrofluid slug or microbead caused by the driving force exerted using a permanent magnet ring has been investigated in a 200μm circular microtube. The motion and behavior of the ferrofluid slug and microbead were observed. In addition, we examined the motion and stopping position.
Effects of Chemical and Physical Shear-Stress Stimulation of Human Placenta-Derived Multipotent Stem Cells in Microchannel
Authors: Tsao Chia-Wen , Chiang Meng-Zhi , Cheng Yu-Che
Published: December 2013

Multipotent cells obtain from human postpartum term placenta is an ethically conductive, easily accessible and high-yielding stem cell source. In this conference presentation, we demonstrate using microchannel platform to culture and differentiate the human placenta-derived stem cells. Both chemical and shear stress stimulation effects were investigated.
Mass Transport Characteristics of Water/IPA at Silica-Liquid Interfaces
Authors: Nakano Takeo , Kosaka Shuichi , Kikugawa Gota , Ohara Taku
Published: December 2013

Molecular dynamics simulations were performed in order to investigate the impact of temperature on molecular structure and mass transport properties in the vicinity of silica-water and/or iso-propyl alcohol (IPA) liquid film interfaces. Each of water and IPA liquid molecules form layered structures in the vicinity of the solid. Although temperature has an insignificant effect on the first layer from the solid, the layered structure at higher temperature decays farther away from the second layer comparing with that at lower temperature for both silica-water and silica-IPA systems. Moreover, interfusion of water and IPA molecules between silica substrates was simulated and molecular coverage on the substrates are analyzed for temperatures of 300 K and 350 K.
Effect of Micro-Structured Surface on Dropwise Condensation Heat Transfer
Authors: Tokunaga Atsushi , Mizutani Masaki , Nagayama Gyoko , Tsuruta Takaharu
Published: December 2013

The micro/nano scale phase change phenomena become more and more important because the MEMS technology develops rapidly in the fields of electro- and bio-devices [1][2] and the MEMS enable us to control the surface wettability. In the dropwise condensation on the hydrophobic surface, the heat transfer coefficient is determined by the departing droplet size. In our previous paper, it was found that the droplets in radius around 7 μm made more significant contribution to the condensation heat transfer under the low-pressure conditions. That is, when the smaller droplets less than 7 μm cover the condensing surface, the higher condensing heat flux would be achieved than that of the ordinary dropwise condensation. However, it is still very difficult to keep the droplets to be continuous condensed within 7 μm at the surface.

A challenging work has been conducted to fabricate a droplets exclusion structure on the condensing surface for the purpose of the enhancement of condensation heat transfer in our previous experiment [3]. By using the MEMS technology, we made the hybrid-condensing surface with hydrophobic and hydrophilic patterns in order to remove the grown droplets effectively. It was found that the hybrid-surface has a possibility to increase the condensation heat transfer coefficient but its drainage-ability of the condensate has the limitation due to the occurrence of the flooding over the surface structures. In order to reduce the flooding at the hydrophobic area, in this study, the new design of the condensing surface has been proposed and the condensation heat transfer coefficient is evaluated.
Performance Improvement in Redox Flow Battery With Flow-Through Channel Geometry
Authors: Tsushima Shohji , Sasaki Sho , Suzuki Takahiro , Deevanhxay Phengxay , Hirai Shuichiro
Published: December 2013

Redox Flow battery attracts much attention as one of the efficient rechargeable batteries because of its versatility for small and large scale energy storage. Although this battery has great potentials, further improvement on cell performance to achieve high current density is necessary for industrial implementation. In this study, we applied flow-through (interdigitated) channel geometry to a redox flow battery for enhancement of electrode utilization by advection transport. As a result, it is confirmed that the redox flow battery showed better performance by using interdigitated channels than ones with serpentine channels.
3D Velocity Measurement by Orthogonal-Plane Micro-PIV for Electrokinetic Enhancement of Surface Reaction
Authors: Ishida Akihiko , Ichimura Daisuke , Motosuke Masahiro
Published: December 2013

In microfluidic systems, surface reaction is diffusion-limited because the effect of convection on mass transport decreases due to low Peclet number. It is indicated that an externally induced flow toward the reactive interface is effective to enhance the efficiency of the surface reaction. However, it is difficult to evaluate the flow velocity normal to the substrate, which directly contributes to the enhancement of the surface reaction, due to the monolithic dimension of microfluidic device. This paper reports the development of a 3D flow velocity measurement method by orthogonal-plane micro-PIV to evaluate the contribution of flow distortion by alternating-current electrokinetic phenomena on the reaction enhancement. 3D velocity field is reconstructed from two orthogonal velocity fields measured by 2D micro-PIV with different measurement planes; one is based on normal observation with the measurement plane parallel to the bottom wall and the other is based on a lateral observation with the plane perpendicular to the bottom wall through a sidewall of a fluidic channel made of PDMS (100 × 50 μm). Complete 3D velocity field is determined by scanning the measurement plane in each observation scheme. Validity of orthogonal-plane micro-PIV for the 3D velocity measurement was confirmed by the measurement of three component velocities in a tilt rectangular microchannel. Then, we investigated AC-driven electrothermal (ACET) effect induced by the property gradient of fluid due to temperature nonuniformity under an electric field application. Effective flow structure of ACET for the enhancement of surface reaction, a circular stirring fluid motion which conveys bulk fluid to the surface region, was observed. This stirring motion of fluid could improve the binding opportunities between suspended and immobilized species and result in the promotion of reaction efficiency. It is clarified that 3D flow of ACET contributes to the localized enhancement of the surface reaction efficiency.
Low-cost Xe sputtering of amorphous In-Ga-Zn-O thin-film transistors by rotation magnet sputtering incorporating a Xe recycle-and-supply system
Authors: Goto Tetsuya , Ishii Hidekazu , Sugawa Shigetoshi , Ohmi Tadahiro
Published: December 2013

A Xe recycle-and-supply system was incorporated into a dual-target rotation magnet sputtering (DT-RMS) process to fabricate amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs). DT-RMS is an upgraded version of the previously reported single-target rotation magnet sputtering system [Goto et al., J. Vac. Sci. Technol. A 27, 653 (2009)] designed to expand deposition area. In DT-RMS, multiple moving plasma loops are excited at the dual-target surface. These plasma loops work to homogenize the properties of the films deposited on the substrates, with time-averaged homogenization of the plasma parameters at the substrate. As a result, film thicknesses and uniform distributions of the a-IGZO-film properties were obtained at an appropriate target–substrate distance. In this configuration, the Xe-sputtered a-IGZO TFTs exhibited higher field-effect mobilities than conventional Ar-sputtered TFTs. When using the recycled Xe supplied from the Xe recycle-and-supply system, the field-effect mobility value was the same as for fresh-Xe sputtered TFTs, demonstrating the technique's potential as a low-cost alternative for providing the flat panel display industry with Xe.
Snuffing Out Marijuana Inflammation
Authors: Berndt Jason D.
Published: December 2013

Inhibition of COX2 may prevent the memory impairment caused by the active ingredient in marijuana.
It Takes a Few
Authors: Hurtley Stella M.
Published: December 2013

Induction of long-term potentiation in a few dendritic spines signals to the nucleus to activate transcription factors.
Paradoxical Growth of Candida albicans in the Presence of Caspofungin Is Associated with Multiple Cell Wall Rearrangements and Decreased Virulence
Authors: Rueda Cristina , Cuenca-Estrella Manuel , Zaragoza Oscar
Published: December 2013

In the last decade, echinocandins have emerged as an important family of antifungal drugs because of their fungicidal activity against
Candida
spp. Echinocandins inhibit the enzyme β-1,3-
d
-glucan synthase, encoded by the
FKS
genes, and resistance to echinocandins is associated with mutations in this gene. In addition, echinocandin exposure can produce paradoxical growth, defined as the ability to grow at high antifungal concentrations but not at intermediate concentrations. In this work, we have demonstrated that paradoxical growth of
Candida albicans
in the presence of caspofungin is not due to antifungal degradation or instability. Media with high caspofungin concentrations recovered from wells where
C. albicans
showed paradoxical growth inhibited the growth of a
Candida krusei
reference strain. Cells exhibiting paradoxical growth at high caspofungin concentrations showed morphological changes such as enlarged size, abnormal septa, and absence of filamentation. Chitin content increased from the MIC to high caspofungin concentrations. Despite the high chitin levels, around 23% of cells died after treatment with caspofungin, indicating that chitin is required but not sufficient to protect the cells from the fungicidal effect of caspofungin. Moreover, we found that after paradoxical growth, β-1,3-glucan was exposed at the cell wall surface. Cells grown at high caspofungin concentrations had decreased virulence in the invertebrate host
Galleria mellonella
. Cells grown at high caspofungin concentrations also induced a proinflammatory response in murine macrophages compared to control cells. Our work highlights important aspects about fungal adaptation to caspofungin, and although this adaptation is associated with reduced virulence, the clinical implications remain to be elucidated.
In Vitro
and
In Vivo
Antibacterial Activities of Omadacycline, a Novel Aminomethylcycline
Authors: Macone A. B. , Caruso B. K. , Leahy R. G. , Donatelli J. , Weir S. , Draper M. P. , Tanaka S. K. , Levy S. B.
Published: December 2013

Omadacycline is the first intravenous and oral 9-aminomethylcycline in clinical development for use against multiple infectious diseases including acute bacterial skin and skin structure infections (ABSSSI), community-acquired bacterial pneumonia (CABP), and urinary tract infections (UTI). The comparative
in vitro
activity of omadacycline was determined against a broad panel of Gram-positive clinical isolates, including methicillin-resistant
Staphylococcus aureus
(MRSA), vancomycin-resistant
Enterococcus
(VRE), Lancefield groups A and B beta-hemolytic streptococci, penicillin-resistant
Streptococcus pneumoniae
(PRSP), and
Haemophilus influenzae
(
H. influenzae
). The omadacycline MIC
90
s for MRSA, VRE, and beta-hemolytic streptococci were 1.0 μg/ml, 0.25 μg/ml, and 0.5 μg/ml, respectively, and the omadacycline MIC
90
s for PRSP and
H. influenzae
were 0.25 μg/ml and 2.0 μg/ml, respectively. Omadacycline was active against organisms demonstrating the two major mechanisms of resistance, ribosomal protection and active tetracycline efflux.
In vivo
efficacy of omadacycline was demonstrated using an intraperitoneal infection model in mice. A single intravenous dose of omadacycline exhibited efficacy against
Streptococcus pneumoniae
,
Escherichia coli
, and
Staphylococcus aureus
, including
tet
(M) and
tet
(K) efflux-containing strains and MRSA strains. The 50% effective doses (ED
50
s) for
Streptococcus pneumoniae
obtained ranged from 0.45 mg/kg to 3.39 mg/kg, the ED
50
s for
Staphylococcus aureus
obtained ranged from 0.30 mg/kg to 1.74 mg/kg, and the ED
50
for
Escherichia coli
was 2.02 mg/kg. These results demonstrate potent
in vivo
efficacy including activity against strains containing common resistance determinants. Omadacycline demonstrated
in vitro
activity against a broad range of Gram-positive and select Gram-negative pathogens, including resistance determinant-containing strains, and this activity translated to potent efficacy
in vivo
.
Efficacy and Safety of Danoprevir-Ritonavir plus Peginterferon Alfa-2a–Ribavirin in Hepatitis C Virus Genotype 1 Prior Null Responders
Authors: Gane Edward J. , Rouzier Régine , Wiercinska-Drapalo Alicja , Larrey Dominique G. , Morcos Peter N. , Brennan Barbara J. , Le Pogam Sophie , Nájera Isabel , Petric Rosemary , Tran Jonathan Q. , Kulkarni Rohit , Zhang Ying , Smith Patrick , Yetzer Ellen S. , Shulman Nancy S.
Published: December 2013

Danoprevir (DNV) is a hepatitis C virus (HCV) protease inhibitor that achieves high sustained virologic response (SVR) rates in combination with peginterferon alfa-2a–ribavirin in treatment-naive HCV genotype 1 (G1)-infected patients. This study explored the efficacy and safety of ritonavir-boosted DNV (DNVr) plus peginterferon alfa-2a–ribavirin in G1-infected prior peginterferon-ribavirin null responders. Null responders (<2-log
10
reduction in HCV RNA level at week 12) were given an open-label combination of 100 mg of ritonavir and 100 mg of DNV (100/100 mg DNVr) every 12 h (q12h) plus peginterferon alfa-2a–ribavirin for 12 weeks. All patients achieving an early virologic response (EVR; ≥2-log
10
decrease in HCV RNA by week 12) continued treatment with peginterferon alfa-2a–ribavirin; those without an EVR discontinued all study drugs. Twenty-four prior null responders were enrolled; 16 patients (67%) were infected with HCV G1b, and 8 (33%) were infected with G1a. Ninety-six percent of patients had an
IL28B
non-CC genotype. A sustained virologic response at 24 weeks posttreatment (SVR24) was achieved in 67% of patients, with a higher rate in G1b-infected (88%) than G1a-infected (25%) patients. Resistance-related breakthrough occurred in 4/8 G1a and 1/16 G1b patients through the DNV resistance-associated variant (RAV) NS3 R155K. NS3 R155K was also detected in 2/2 G1a patients who relapsed. Treatment was well tolerated. Two patients withdrew prematurely from study medications due to adverse events. Two serious adverse events were reported; both occurred after completion of DNVr therapy and were considered unrelated to treatment. No grade 3 or 4 alanine aminotransferase (ALT) elevations were observed. DNVr plus peginterferon alfa-2a–ribavirin demonstrated high SVR24 rates in HCV G1b-infected prior null responders and was well tolerated. (This study has been registered at
ClinicalTrials.gov
under registration no. NCT01185860.)
Detection of Carbapenemase-Producing Bacteria by Using an Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry Method
Authors: Carricajo Anne , Verhoeven Paul O. , Guezzou Salim , Fonsale Nathalie , Aubert Gerald
Published: December 2013

The emergence of carbapenemase-producing bacteria poses a new challenge in the management of antibiotic therapies for patients. This report describes a new method using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) for rapid detection of carbapenemase activity in enterobacteria,
Pseudomonas aeruginosa
, and
Acinetobacter baumannii
. In a panel of 78 isolates, including 41 carbapenemase-producing strains, the ULPC-MS/MS assay showed 100% agreement with molecular characterization, whereas six carbapenemase-producing isolates were not detected by the modified Hodge test.
Oxacillin Alters the Toxin Expression Profile of Community-Associated Methicillin-Resistant Staphylococcus aureus
Authors: Rudkin Justine K. , Laabei Maisem , Edwards Andrew M. , Joo Hwang-Soo , Otto Michael , Lennon Katrina L. , O'Gara James P. , Waterfield Nicholas R. , Massey Ruth C.
Published: December 2013

The emergence of community-associated methicillin-resistant
Staphylococcus aureus
(CA-MRSA) is a growing cause for concern. These strains are more virulent than health care-associated MRSA (HA-MRSA) due to higher levels of toxin expression. In a previous study, we showed that the high-level expression of PBP2a, the alternative penicillin binding protein encoded by the
mecA
gene on type II staphylococcal cassette chromosome
mec
(SCC
mec
) elements, reduced toxicity by interfering with the Agr quorum sensing system. This was not seen in strains carrying the CA-MRSA-associated type IV SCC
mec
element. These strains express significantly lower levels of PBP2a than the other MRSA type, which may explain their relatively high toxicity. We hypothesized that as oxacillin is known to increase
mecA
expression levels, it may be possible to attenuate the toxicity of CA-MRSA by using this antibiotic. Subinhibitory oxacillin concentrations induced PBP2a expression, repressed Agr activity, and, as a consequence, decreased phenol-soluble modulin (PSM) secretion by CA-MRSA strains. However, consistent with other studies, oxacillin also increased the expression levels of alpha-toxin and Panton-Valentine leucocidin (PVL). The net effect of these changes on the ability to lyse diverse cell types was tested, and we found that where the PSMs and alpha-toxin are important, oxacillin reduced overall lytic activity, but where PVL is important, it increased lytic activity, demonstrating the pleiotropic effect of oxacillin on toxin expression by CA-MRSA.
Intersubspecific Recombination in Xylella fastidiosa Strains Native to the United States: Infection of Novel Hosts Associated with an Unsuccessful Invasion
Authors: Nunney Leonard , Hopkins Donald L. , Morano Lisa D. , Russell Stephanie E. , Stouthamer Richard
Published: December 2013

The bacterial pathogen
Xylella fastidiosa
infects xylem and causes disease in many plant species in the Americas. Different subspecies of this bacterium and different genotypes within subspecies infect different plant hosts, but the genetics of host adaptation are unknown. Here we examined the hypothesis that the introduction of novel genetic variation via intersubspecific homologous recombination (IHR) facilitates host shifts. We investigated IHR in 33
X. fastidiosa
subsp.
multiplex
isolates previously identified as recombinant based on 8 loci (7 multilocus sequence typing [MLST] loci plus 1 locus). We found significant evidence of introgression from
X. fastidiosa
subsp.
fastidiosa
in 4 of the loci and, using published data, evidence of IHR in 6 of 9 additional loci. Our data showed that IHR regions in 2 of the 4 loci were inconsistent (12 mismatches) with
X. fastidiosa
subsp.
fastidiosa
alleles found in the United States but consistent with alleles from Central America. The other two loci were consistent with alleles from both regions. We propose that the recombinant forms all originated via genomewide recombination of one
X. fastidiosa
subsp.
multiplex
ancestor with one
X. fastidiosa
subsp.
fastidiosa
donor from Central America that was introduced into the United States but subsequently disappeared. Using all of the available data, 5 plant hosts of the recombinant types were identified, 3 of which also supported non-IHR
X. fastidiosa
subsp.
multiplex
, but 2 were unique to recombinant types from blueberry (7 isolates from Georgia, 3 from Florida); and blackberry (1 each from Florida and North Carolina), strongly supporting the hypothesis that IHR facilitated a host shift to blueberry and possibly blackberry.
Ingestibility, Digestibility, and Engineered Biological Control Potential of Flavobacterium
hibernum
, Isolated from Larval Mosquito Habitats
Authors: Chen Shicheng , Kaufman Michael G. , Korir Michelle L. , Walker Edward D.
Published: December 2013

Flavobacterium
hibernum
, isolated from larval habitats of the eastern tree hole mosquito,
A. triseriatus
, remained suspended in the larval feeding zone much longer (8 days) than other bacteria. Autofluorescent protein markers were developed for the labeling of
F. hibernum
with a strong flavobacterial expression system. Green fluorescent protein (GFP)-tagged
F. hibernum
cells were quickly consumed by larval mosquitoes at an ingestion rate of 9.5 × 10
4
/larva/h. The ingested
F. hibernum
cells were observed mostly in the foregut and midgut and rarely in the hindgut, suggesting that cells were digested and did not pass the gut viably. The NanoLuc luciferase reporter system was validated for quantitative larval ingestion rate and bacterial fate analyses. Larvae digested 1.87 × 10
5
cells/larva/h, and few
F. hibernum
cells were excreted intact. Expression of the GFP::Cry11A fusion protein with the P20 chaperone protein from
Bacillus thuringiensis
H-14 was successfully achieved in
F. hibernum
. Whole-cell bioassays of recombinant
F. hibernum
exhibited high larvicidal activity against
A. triseriatus
in microplates and in microcosms simulating tree holes.
F. hibernum
cells persisted in microcosms at 100, 59, 30, and 10% of the initial densities at days 1, 2, 3, and 6, respectively, when larvae were absent, while larvae consumed nearly all of the
F. hibernum
cells within 3 days of their addition to microcosms.
Use of Limited Proteolysis and Mutagenesis To Identify Folding Domains and Sequence Motifs Critical for Wax Ester Synthase/Acyl Coenzyme A:Diacylglycerol Acyltransferase Activity
Authors: Villa Juan A. , Cabezas Matilde , de la Cruz Fernando , Moncalián Gabriel
Published: December 2013

Triacylglycerols and wax esters are synthesized as energy storage molecules by some proteobacteria and actinobacteria under stress. The enzyme responsible for neutral lipid accumulation is the bifunctional wax ester synthase/acyl-coenzyme A (CoA):diacylglycerol acyltransferase (WS/DGAT). Structural modeling of WS/DGAT suggests that it can adopt an acyl-CoA-dependent acyltransferase fold with the N-terminal and C-terminal domains connected by a helical linker, an architecture demonstrated experimentally by limited proteolysis. Moreover, we found that both domains form an active complex when coexpressed as independent polypeptides. The structural prediction and sequence alignment of different WS/DGAT proteins indicated catalytically important motifs in the enzyme. Their role was probed by measuring the activities of a series of alanine scanning mutants. Our study underscores the structural understanding of this protein family and paves the way for their modification to improve the production of neutral lipids.
Characterization of Biofilm Formation and the Role of
BCR1
in Clinical Isolates of Candida parapsilosis
Authors: Pannanusorn Srisuda , Ramírez-Zavala Bernardo , Lünsdorf Heinrich , Agerberth Birgitta , Morschhäuser Joachim , Römling Ute
Published: December 2013

In
Candida parapsilosis
, biofilm formation is considered to be a major virulence factor. Previously, we determined the ability of 33 clinical isolates causing bloodstream infection to form biofilms and identified three distinct groups of biofilm-forming strains (negative, low, and high). Here, we establish two different biofilm structures among strains forming large amounts of biofilm in which strains with complex spider-like structures formed robust biofilms on different surface materials with increased resistance to fluconazole. Surprisingly, the transcription factor Bcr1, required for biofilm formation in
Candida albicans
and
C. parapsilosis
, has an essential role only in strains with low capacity for biofilm formation. Although
BCR1
leads to the formation of more and longer pseudohyphae, it was not required for initial adhesion and formation of mature biofilms in strains with a high level of biofilm formation. Furthermore, an additional phenotype affected by
BCR1
was the switch in colony morphology from rough to crepe, but only in strains forming high levels of biofilm. All
bcr1
Δ/Δ mutants showed increased proteolytic activity and increased susceptibility to the antimicrobial peptides protamine and RP-1 compared to corresponding wild-type and complemented strains. Taken together, our results demonstrate that biofilm formation in clinical isolates of
C. parapsilosis
is both dependent and independent of
BCR1
, but even in strains which showed a
BCR1
-independent biofilm phenotype,
BCR1
has alternative physiological functions.
Giardia intestinalis Incorporates Heme into Cytosolic Cytochrome
b
5
Authors: Pyrih Jan , Harant Karel , Martincová Eva , Sutak Robert , Lesuisse Emmanuel , Hrdý Ivan , Tachezy Jan
Published: December 2013

The anaerobic intestinal pathogen
Giardia intestinalis
does not possess enzymes for heme synthesis, and it also lacks the typical set of hemoproteins that are involved in mitochondrial respiration and cellular oxygen stress management. Nevertheless,
G. intestinalis
may require heme for the function of particular hemoproteins, such as cytochrome
b
5
(cyt
b
5
). We have analyzed the sequences of eukaryotic cyt
b
5
proteins and identified three distinct cyt
b
5
groups: group I, which consists of C-tail membrane-anchored cyt
b
5
proteins; group II, which includes soluble cyt
b
5
proteins; and group III, which comprises the fungal cyt
b
5
proteins. The majority of eukaryotes possess both group I and II cyt
b
5
proteins, whereas three
Giardia
paralogs belong to group II. We have identified a fourth
Giardia
cyt
b
5
paralog (gCYTb5-IV) that is rather divergent and possesses an unusual 134-residue N-terminal extension. Recombinant
Giardia
cyt
b
5
proteins, including gCYTb5-IV, were expressed in
Escherichia coli
and exhibited characteristic UV-visible spectra that corresponded to heme-loaded cyt
b
5
proteins. The expression of the recombinant gCYTb5-IV in
G. intestinalis
resulted in the increased import of extracellular heme and its incorporation into the protein, whereas this effect was not observed when gCYTb5-IV containing a mutated heme-binding site was expressed. The electrons for
Giardia
cyt
b
5
proteins may be provided by the NADPH-dependent Tah18-like oxidoreductase GiOR-1. Therefore, GiOR-1 and cyt
b
5
may constitute a novel redox system in
G. intestinalis
. To our knowledge,
G. intestinalis
is the first anaerobic eukaryote in which the presence of heme has been directly demonstrated.
The
phtC-phtD
Locus Equips Legionella pneumophila for Thymidine Salvage and Replication in Macrophages
Authors: Fonseca Maris V. , Sauer John-Demian , Crepin Sebastien , Byrne Brenda , Swanson Michele S.
Published: December 2013

The phagosomal transporter (Pht) family of the major facilitator superfamily (MFS) is encoded by phylogenetically related intracellular gammaproteobacteria, including the opportunistic pathogen
Legionella pneumophila
. The location of the
pht
genes between the putative thymidine kinase (
tdk
) and phosphopentomutase (
deoB
) genes suggested that the
phtC
and
phtD
loci contribute to thymidine salvage in
L. pneumophila
. Indeed, a
phtC

+

allele in
trans
restored pyrimidine uptake to an
Escherichia coli
mutant that lacked all known nucleoside transporters, whereas a
phtD

+

allele did not. The results of phenotypic analyses of
L. pneumophila
strains lacking
phtC
or
phtD
strongly indicate that
L. pneumophila
requires PhtC and PhtD function under conditions where sustained dTMP synthesis is compromised. First, in broth cultures that mimicked thymidine limitation or starvation,
L. pneumophila
exhibited a marked requirement for PhtC function. Conversely, mutation of
phtD
conferred a survival advantage. Second, in medium that lacked thymidine, multicopy
phtC

+

or
phtD

+

alleles enhanced the survival of
L. pneumophila
thymidylate synthase (
thyA
)-deficient strains, which cannot synthesize dTMP endogenously. Third, under conditions in which transport of the pyrimidine nucleoside analog 5-fluorodeoxyuridine (FUdR) would inhibit growth, PhtC and PhtD conferred a growth advantage to
L. pneumophila
thyA

+

strains. Finally, when cultured in macrophages,
L. pneumophila
required the
phtC-phtD
locus to replicate. Accordingly, we propose that PhtC and PhtD contribute to protect
L. pneumophila
from dTMP starvation during its intracellular life cycle.
Host-Nonspecific Iron Acquisition Systems and Virulence in the Zoonotic Serovar of Vibrio vulnificus
Authors: Pajuelo David , Lee Chung-Te , Roig Francisco J. , Lemos Manuel L. , Hor Lien-I , Amaro Carmen
Published: December 2013

The zoonotic serovar of
Vibrio vulnificus
(known as biotype 2 serovar E) is the etiological agent of human and fish vibriosis. The aim of the present work was to discover the role of the vulnibactin- and hemin-dependent iron acquisition systems in the pathogenicity of this zoonotic serovar under the hypothesis that both are host-nonspecific virulence factors. To this end, we selected three genes for three outer membrane receptors (
vuuA
, a receptor for ferric vulnibactin, and
hupA
and
hutR
, two hemin receptors), obtained single and multiple mutants as well as complemented strains, and tested them in a series of
in vitro
and
in vivo
assays, using eels and mice as animal models. The overall results confirm that
hupA
and
vuuA
, but not
hutR
, are host-nonspecific virulence genes and suggest that a third undescribed host-specific plasmid-encoded system could also be used by the zoonotic serovar in fish.
hupA
and
vuuA
were expressed in the internal organs of the animals in the first 24 h of infection, suggesting that they may be needed to achieve the population size required to trigger fatal septicemia.
vuuA
and
hupA
were sequenced in strains representative of the genetic diversity of this species, and their phylogenies were reconstructed by multilocus sequence analysis of selected housekeeping and virulence genes as a reference. Given the overall results, we suggest that both genes might form part of the core genes essential not only for disease development but also for the survival of this species in its natural reservoir, the aquatic environment.
Response to Metronidazole and Oxidative Stress Is Mediated through Homeostatic Regulator HsrA (HP1043) in Helicobacter pylori
Authors: Olekhnovich Igor N. , Vitko Serhiy , Valliere Meaghan , Hoffman Paul S.
Published: December 2013

Metronidazole (MTZ) is often used in combination therapies to treat infections caused by the gastric pathogen
Helicobacter pylori
. Resistance to MTZ results from loss-of-function mutations in genes encoding RdxA and FrxA nitroreductases. MTZ-resistant strains, when cultured at sub-MICs of MTZ (5 to 20 μg/ml), show dose-dependent defects in bacterial growth; depressed activities of many Krebs cycle enzymes, including pyruvate:ferredoxin oxidoreductase (PFOR); and low transcript levels of
porGDAB
(primer extension), phenotypes consistent with an involvement of a transcriptional regulator. Using a combination of protein purification steps, electrophoretic mobility shift assays (EMSAs), and mass spectrometry analyses of proteins bound to
porG
promoter sequences, we identified HP1043, an essential homeostatic global regulator (HsrA [for
h
omeostatic
s
tress
r
egulator]). Competition EMSAs and supershift analyses with HsrA-enriched protein fractions confirmed specific binding to
porGDAB
and
hsrA
promoter sequences. Exposure to MTZ resulted in >10-fold decreases in levels of HsrA and in levels of the HsrA-regulated gene products PFOR and TlpB. Exposure to paraquat (PQ), hydrogen peroxide, or organic peroxides showed near equivalence with MTZ, revealing a common oxidative stress response pathway. Finally, direct superoxide dismutase (SOD) assays showed an inverse relationship between HsrA levels and SOD activity, suggesting that HsrA may serve as a repressor of
sodB
. As a homeostatic sentinel, HsrA appears to be ideally positioned to enable rapid shutdown of genes associated with metabolism and growth while activating (directly or indirectly) oxidative defense genes in response to low levels of toxic metabolites (MTZ or oxygen) before they reach DNA-damaging levels.
Amino-4-Imidazolecarboxamide Ribotide Directly Inhibits Coenzyme A Biosynthesis in Salmonella enterica
Authors: Bazurto Jannell V. , Downs Diana M.
Published: December 2013

Aminoimidazole carboxamide ribotide (AICAR) is a purine biosynthetic intermediate and a by-product of histidine biosynthesis. In bacteria, yeast, and humans, accumulation of AICAR has been shown to affect an array of cellular processes by both direct and indirect mechanisms. In purine biosynthesis, AICAR is the substrate of the bifunctional protein phosphoribosylaminoimidazolecarboxamide formyltransferase/IMP cyclohydrolase (PurH, EC 2.1.2.3/3.5.4.10). Strains lacking PurH accumulate AICAR and have a defect in the synthesis of the 4-amino-5-hydroxymethyl-2-methylpyrimidine (HMP) moiety of thiamine. The formation of HMP is also compromised
in vivo
when coenzyme A (CoA) levels are reduced. Our results show that the
in vivo
accumulation of AICAR decreased total CoA pools and, further, that AICAR inhibited the activity of pantoate β-alanine ligase
in vitro
(PanC, EC 6.3.2.1). These results demonstrated a mechanism of AICAR action and provide new insights into the metabolic consequences of disrupting purine metabolism.
A sneeze: an unusual trigger for aortic dissection
Authors: Upadhyaya Subramanya G N , Large A
Published: December 2013

We describe a rare case of type B thoracic aortic dissection resulting from a forceful sneeze in a 57-year-old man. The presenting clinical features were not typical and consisted of pleuritic chest pain and breathlessness following a forceful sneeze. There was no haemodynamic compromise. The diagnosis was made incidentally when he underwent a CT pulmonary angiography as part of pulmonary embolism work-up.
Nutrient removal (nitrogen and phosphorous) in secondary effluent from a wastewater treatment plant by microalgae
Authors: Chan Alison , Salsali Hamidreza , McBean Ed
Published: December 2013

Microalgae as a feasible option to remove nutrients (phosphorous and nitrogen) from domestic wastewater treatment plant discharge is demonstrated. Laboratory-scale experiments are described, characterizing nutrient removal of total phosphorous and ammonia by three cultured microalgae strains: Chlorella vulgaris, Spirulina maxima, and mixed cultures of naturally growing algae found in wastewater from the Collingwood Wastewater Treatment Plant in Ontario, Canada containing Synechocystis sp. (dominant), Chlorella sp. (common), and a few cells of Scenedesmus sp. Removal of phosphates strongly positively relates to solution pH. Volatilization of ammonia due to increase in pH is not a dominant contributor to overall removal efficiency. Total phosphorous removal rates reached 95.8% and 90.4% for untreated and autoclaved secondary effluent, respectively. Ammonia removal rates reached 94.6% and 86.2% for untreated and autoclaved secondary effluent, respectively. These results demonstrate that use of microalgae represents a sustainable approach to improve removal efficiencies of nutrients in wastewater treatment.
ANALYTICAL MODELS AND ELECTRICAL CHARACTERISATION OF ADVANCED MOSFETs IN THE QUASI BALLISTIC REGIME
Authors: CLERC RAPHAEL , GHIBAUDO GERARD
Published: December 2013

The quasi-ballistic nature of transport in end of the roadmap MOSFETs device is expected to lead to significant on state current enhancement. The current understanding of such mechanism of transport is carefully reviewed in this chapter, underlining the derivation and limits of corresponding analytical models. In a second part, different strategies to compare these models to experiments are discussed, trying to estimate the “degree of ballisticity” achieved in advanced technologies.
SYNTHESIS OF NANOCOMPOSITES OF POLYVINYL ALCOHOL WITH SILVER NANOPARTICLES AND THEIR USE
Authors: BHAT N. V. , KARMAKAR N. S. , KOTHARI D. C.
Published: December 2013

Composites of polyvinyl alcohol (PVA) containing silver nanoparticles were prepared using in situ synthesis of nanoparticles. Structure and properties of these composites were investigated using UV-Vis spectroscopy, XRD, DSC, SEM and AFM. The studies show that PVA can reduce the AgNO 3 to yield silver nanoparticles and in the process forms bonds with PVA chains. The anti-bacterial properties of these films were studied by qualitative as well as quantitative methods which gave the values of 98% for gram positive and 89% for gram negative bacteria.
EXAMINING THE CULTURAL MODERATION ON THE ACCEPTANCE OF MOBILE COMMERCE
Authors: HUNG CHIA-LIANG , CHOU JEROME CHIH-LUNG
Published: December 2013

This study identifies the cultural influences on the adoption of mobile commerce based on the comparative cases of Taiwan and Malaysia, so as to give insights to mobile operators' global entries. Using Hofstede's five cultural orientations as moderators in conjunction to Davis' technology acceptance model (TAM), the combined model has been tested by the confirmatory factor analysis for measurement validity and the multiple regression approach for the moderation effect of cultural influences on the adoption of novel mobile services. This results show that uncertainty avoidance (UA), individualism (ID), and long-term (LT) orientation have significant influences on the influence of perceived usefulness (PU) and perceived ease-of-use (PEOU) regarding the adoption intentions of mobile commerce. However, the power distance (PD) and masculinity (MA) have different effects in Taiwan and Malaysia. These results not only supplement the explanation of the technology adoption, but also hold strategic implications for the global expansion of mobile operators by emphasizing on local preferences and their differentiation advantages.
The first synthesis of sandwich-type complex based on tetradiazepinoporphyrazine ligand
Authors: Tarakanova Ekaterina N. , Tarakanov Pavel A. , Pushkarev Victor E. , Tomilova Larisa G.
Published: December 2013

Sandwich-type complex based on tetradiazepinoporphyrazine ligand — bis{tetrakis(5,7-di(4-tert-butylphenyl)-6H-1,4-diazepino)[2,3-b,g,l,q]porphyrazinato}lutetium — was synthesized for the first time. The structure of the compound has been confirmed by UV-vis/NIR, 1 H NMR spectroscopy, and MALDI-TOF mass spectrometry data. The introduction of annulated diazepine heterocycles to porphyrazine molecule significantly changes macrocycle reactivity and results in sandwich-type complex under conditions used for the selective synthesis of lanthanide(III) monophthalocyanines.
Electronic tongue formed by sensors and biosensors containing phthalocyanines as electron mediators: Application to the analysis of red grapes
Authors: Medina-Plaza Cristina , Revilla Gema , Muñoz Raquel , Fernández-Escudero José Antonio , Barajas Enrique , Medrano Germán , de Saja José Antonio , Rodriguez-Mendez Maria Luz
Published: December 2013

An electronic tongue formed by voltammetric sensors and biosensors containing phthalocyanines has been developed and used to analyze grapes of different varieties. The sensors are prepared using the carbon paste technique and have been chemically modified with different metallophthalocyanines. In turn, biosensors consist of carbon paste electrodes modified with phthalocyanines combined with tyrosinase or glucose oxidase. The response of the individual sensors towards model solutions of glucose and catechol have demonstrated that the voltammetric responses depend on the nature of the phthalocyanine, evidencing the important role of the electron mediator in the performance of the sensors. The capability of the system to discriminate grapes according to their sugar and their polyphenolic content has been evidenced using Principal Component Analysis. It has been demonstrated that the proposed array of sensors combines the advantages of classical phthalocyanine based sensors — that provide global information about the sample —, with the specificity of the enzyme substrate reaction typical of biosensors. For this reason, the selectivity of the multisensor system and its capability of discrimination is clearly improved when biosensors containing glucose oxidase or tyrosinase are included in the array.
Synthesis and properties of tetra- and octacationicmeso-tetrakis(3-pyridyl)bacteriochlorin derivatives
Authors: Dudkin Semyon V. , Makarova Elena A. , Slivka Ludmila K. , Lukyanets Evgeny A.
Published: December 2013

The synthesis and properties of new water-soluble tetra- and octacationic derivatives of meso-tetrakis(3-pyridyl)bacteriochlorin are reported. Tetracationic salt was synthesized by quaternization of the pyridine groups of starting bacteriochlorin with 1,4-dibromobutane. Octacationic salts were obtained by treating of tetracationic salt with excess of pyridine or N,N-dimethylaminoethanol. Zinc complexes of water-soluble bacteriochlorin derivatives were prepared by direct metalation of corresponding non-metal compounds with zinc acetylacetonate, unlike to neutral bacteriochlorin which forms zinc complex only by transmetalation of the corresponding cadmium complex. The new bacteriochlorins have strong absorption in red and NIR spectral region. Free-base BCs possess good stability in aqueous solutions as compared to their zinc complexes and efficiently generate singlet oxygen.
Dynamics of late Cenozoic aeolian deposition along the South African coast: a record of evolving climate and ecosystems
Authors: Roberts Dave , Cawthra Hayley , Musekiwa Chiedza
Published: December 2013

Dune systems along the South African coast are sensitive barometers of fluctuations in palaeoenvironments, as archived in their orientation, geometry, internal architecture, composition, granulometry, diagenesis, palaeontology and archaeological content. Presently, the pronounced climatic/oceanographic gradients around the southern African coastline, including the west coast Mediterranean climate type, with cold upwelling to progressively warmer in terms of climate and sea temperatures eastwards, are mirrored by variations in these parameters. Here, we review and contribute new information concerning their fluctuations from the Miocene to the present to track changes in the bio-, hydro- and geospheres through time. West coast dunes take the form of dune plumes, which have an orientation since the Miocene that mirrors the southerlies of the South Atlantic Anticyclone (SAA), muted during the warm Pliocene, as reflected by intense bioturbation. Shoreline-parallel, vertically aggraded dune cordons dominate along the southern and eastern coasts, formed by (winter) polar westerlies since the Miocene. The contrasting dunefield morphologies relate to seasonality of wind strength and precipitation. Subtropical east coast dunes are profoundly weathered – on the shelf, glacial-period dunes indicate different atmospheric circulations. The long-term stability of the warm Agulhas Current contrasts with variability in the Benguela. The aeolianites host a rich human and faunal archive, including human ichnofossils.

Supplementary material:

Tables S1 and S2, which provide details of the data and data sources for Figure
9
in the text, are available at
http://www.geolsoc.org.uk/SUP18711
.
Compressed suffix trees
Authors: Gog Simon , Ohlebusch Enno
Published: December 2013

The suffix tree is a very important data structure in string processing, but typical implementations suffer from huge space consumption. In large-scale applications, compressed suffix trees (CSTs) are therefore used instead. A CST consists of three (compressed) components: the suffix array, the longest common prefix (LCP)-array and data structures for simulating navigational operations on the suffix tree. The LCP-array stores the lengths of the LCPs of lexicographically adjacent suffixes, and it can be computed in linear time. In this article, we present a new LCP-array construction algorithm that is fast and very space efficient. In practice, our algorithm outperforms alternative algorithms. Moreover, we introduce a new compressed representation of LCP-arrays.