bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seasonal variation and impact factors of available phosphorus in typical paddy soils of Taihu Lake region, China
Authors: Chen Xiaomin , Fang Kun , Chen Can 
Published: December 2011

AbstractPhosphorus loss from soil can play an important role in eutrophication of aquatic bodies. The seasonal variation of available phosphorus in soil profiles of three major paddy soils (Bai soil, Huangni soil and Wushan soil) during wheat and rice growth seasons was studied in the Taihu Lake region of China. The results were as follows: the available phosphorus contents differed in the three paddy soils. Available phosphorus content in Bai soil was the lowest in these soils. The available phosphorus content decreases rapidly with depth from the soil surface and reach the minimum value at approximately 45 cm before increasing slightly near the groundwater. The contents of available phosphorus were higher in February (tillering and shooting period of wheat) and in September (full heading time of rice) than in other months. The total phosphorus content strongly affects available phosphorus content in the studied soils. During the period of wheat cultivation, they show a typical power function relationship with correlation coefficient r = 0.6492** (n = 13), a significant positive linear correlation. In addition, available phosphorus content has a remarkable positive linear correlation with organic matter content, r = 0.9111** (n = 13), and a remarkable negative linear correlation with pH value, r = −0.5945* (n = 13). In Wushan soil, there is a negative linear correlation between clay content and available phosphorus content, r = −0.9289* (n = 4). Therefore, total phosphorus content, organic matter content and pH value are major impact factors on available phosphorus content in these soils.
The evaluation of low‐cost biosorbents for removal of an azo dye from aqueous solution
Authors: Kahraman Sibel , Yalcin Pelin , Kahraman Hüseyin 
Published: December 2011

AbstractThere is a need to develop innovative and alternative technologies that can remove dyes from wastewater. In this study, low‐cost and locally available two renewable biosorbents (cotton stalk and apricot seed) were investigated to remove of Astrazone Black from aqueous solution. The effects of various experimental parameters such as dye concentration, adsorbent amount, adsorbent particle size and initial pH were tested, and optimal experimental conditions were examined. The results showed that as the amount of adsorbent was increased, the percentage of dye removal increased accordingly. The ratios of dye sorbed increased as the adsorbent particle size decreased. In addition, antibacterial effect of untreated and treated (decolourized) dye on a soil bacterium, Pseudomonas aeruginosa, was determined. The removal of this dye with agricultural wastes reduced the toxic effect on P. aeruginosa. This reduction in toxic effect is important both in respect of environmental biotechnology and waste detoxification.
Validation of Assessment for Learning Questionnaires for teachers and students
Authors: Pat‐El Ron Jonathan , Tillema Harm , Segers Mien , Vedder Paul 
Published: December 2011

Background. Assessment can be a powerful force in promoting student learning. Still, few measures exist to gauge Assessment for Learning (AFL) in the classroom. Literature on AFL suggests that it encompasses both a monitor to track student progress as well as a scaffold to show or help students recognize in what areas they need to improve.Aims. Based on a review of recent attempts to measure the AFL, we constructed Assessment for Learning Questionnaires for Teachers (TAFL‐Q) and for students (SAFL‐Q) for evaluating perceptions regarding AFL practices in classrooms using matching items.Sample. The total sample included 1,422 students (49% girls, 51% boys) and 237 teachers (43% females, 57% males) in lower vocational secondary education.Methods. The 28‐item questionnaires were examined by means of confirmatory factor analysis (CFA) using EQS on one random half of the sample. The CFA was cross‐validated on the second half. Measurement invariance tests were conducted to compare the students and teacher versions of the questionnaires.Results. CFA revealed a stable second‐order two‐factor structure that was cross‐validated: perceived monitoring, and perceived scaffolding subsumed under a common factor: AFL. Tests for measurement invariance showed that the parallel constructs were measured similarly for both students and teachers.Conclusion. The TAFL‐Q and SAFL‐Q capture the construct AFL in two subscales: Monitoring and Scaffolding, and allows for comparisons between teacher and student perceptions. The instruments can be useful tools for teachers and students alike to identify and scrutinize assessment practices in classroom.
Optimizing Ultrasonic Additive Manufactured Al 3003 Properties With Statistical Modeling
Authors: Hopkins C. D. , Wolcott P. J. , Dapino M. J. , Truog A. G. , Babu S. S. , Fernandez S. A. 
Published: December 2011

Ultrasonic additive manufacturing (UAM) has proven useful in the solid-state, low tempe’rature fabrication of layered solid metal structures. It is necessary to optimize the various process variables that affect the quality of bonding between layers through investigation of the mechanical strength of various UAM builds. We investigate the effect of the process parameters tack force, weld force, oscillation amplitude, and weld rate on the ultimate shear strength (USS) and ultimate transverse tensile strength (UTTS) of 3003-H18 aluminum UAM built samples. A multifactorial experiment was designed and an analysis of variance was performed to obtain an optimal set of process parameters for maximizing mechanical strength for the tested factors. The statistical analyses indicate that a relatively high mechanical strength can be achieved with a process window bounded by a 350 N tack force, 1000 N weld force, 26 μm oscillation amplitude, and about 42 mm/s weld rate. Optical analyses of bond characterization did not show a consistent correlation linking linear weld density and bonded area of fractured surfaces to mechanical strength. Therefore, scanning electronmicroscopy (SEM) was conducted on fractured samples showing a good correlation between mechanical strength and area fraction that shows ductile failure.
Identification of New Antileishmanial Leads from Hits Obtained by High-Throughput Screening
Authors: Zhu Xiaohua , Pandharkar Trupti , Werbovetz Karl 
Published: December 2011

ABSTRACT

A previous screen of ∼200,000 compounds from the PubChem database identified 70 compounds possessing 50% effective concentrations (EC
50
s) below 1 μM against
Leishmania major
promastigotes that were not toxic to mammalian epithelial cancer cells at this concentration (E. Sharlow et al., PLoS Negl. Trop. Dis. 3:e540, 2009). Based on availability and chemical exclusion criteria, 31 of these compounds were purchased from commercial suppliers and evaluated for
in vitro
activity against intracellular
L. donovani
and
L. amazonensis
parasites. Benzothiazole cyanine compounds (PubChem 16196319 and 16196223) displayed potent activity against intracellular amastigotes, prompting a search for commercially available compounds that were structurally related. Pubchem 123859 (the cyanine dye thiazole orange) showed exceptionally potent activity against intracellular
L. donovani in vitro
(50% inhibitory concentration [IC
50
] = 21 ± 12 nM) and low cytotoxicity against Vero cells (IC
50
= 7,800 ± 200 nM). Administration of 123859 and 16196319 at a dose of 1 mg/kg of body weight intraperitoneally (i.p.) daily for 5 days resulted in 44% ± 4% and 42% ± 3% suppression of liver parasitemia in
L. donovani
-infected BALB/c mice, respectively, compared to the untreated control group (the reductions in liver parasitemia were 30% ± 5% and 27% ± 4%, respectively, compared to the (2-hydroxypropyl)-β-cyclodextrin solution (HPβCD) vehicle control, which itself displayed some antileishmanial activity). Benzothiazole-containing cyanine dyes are thus potential lead compounds for the discovery of novel antileishmanial agents.
Aerosolized Gentamicin Reduces the Burden of Tuberculosis in a Murine Model
Authors: Roy Chad J. , Sivasubramani Satheesh K. , Dutta Noton K. , Mehra Smriti , Golden Nadia A. , Killeen Stephanie , Talton James D. , Hammoud Badre E. , Didier Peter J. , Kaushal Deepak 
Published: December 2011

ABSTRACT

Tuberculosis (TB) is a major infectious disease problem: 1.7 million people annually die due to TB. Emergence of drug-resistant
Mycobacterium tuberculosis
and the lack of new antibiotics have exacerbated the situation. There is an urgent need to develop or repurpose drugs against TB. We evaluated inhaled gentamicin as direct respiratory system-targeted therapy in a murine model of TB. Aerosolized-gentamicin-treated mice showed significantly reduced lung
M. tuberculosis
loads and fewer granulomas relative to untreated controls. These results suggest that direct delivery of antibiotics to the respiratory system may provide therapeutic benefit to conventional treatment regimes for treatment of pulmonary TB.
Molecular Analyses of TEM Genes and Their Corresponding Penicillinase-Producing Neisseria gonorrhoeae Isolates in Bangkok, Thailand
Authors: Nakayama Shu-ichi , Tribuddharat Chanwit , Prombhul Sasiprapa , Shimuta Ken , Srifuengfung Somporn , Unemo Magnus , Ohnishi Makoto 
Published: December 2011

ABSTRACTNeisseria gonorrhoeaeis a major public health problem globally, especially because the bacterium has developed resistance to most antimicrobials introduced for first-line treatment of gonorrhea. In the present study, 96N. gonorrhoeaeisolates with high-level resistance to penicillin from 121 clinical isolates in Thailand were examined to investigate changes related to their plasmid-mediated penicillin resistance and their molecular epidemiological relationships. A β-lactamase (TEM) gene variant,blaTEM-135, that may be a precursor in the transitional stage of a traditionalblaTEM-1gene into an extended-spectrum β-lactamase (ESBL), possibly causing high resistance to all extended-spectrum cephalosporins inN. gonorrhoeae, was identified. Clonal analysis using multilocus sequence typing (MLST) andN. gonorrhoeaemultiantigen sequence typing (NG-MAST) revealed the existence of a sexual network among patients from Japan and Thailand. Molecular analysis of theblaTEM-135gene showed that the emergence of this allele might not be a rare genetic event and that the allele has evolved in different plasmid backgrounds, which results possibly indicate that it is selected due to antimicrobial pressure. The presence of theblaTEM-135allele in the penicillinase-producingN. gonorrhoeaepopulation may call for monitoring for the possible emergence of ESBL-producingN. gonorrhoeaein the future. This study identified ablaTEMvariant (blaTEM-135) that is a possible intermediate precursor for an ESBL, which warrants international awareness.
Resistance to Linezolid Caused by Modifications at Its Binding Site on the Ribosome
Authors: Long Katherine S. , Vester Birte 
Published: December 2011

ABSTRACT
Linezolid is an oxazolidinone antibiotic in clinical use for the treatment of serious infections of resistant Gram-positive bacteria. It inhibits protein synthesis by binding to the peptidyl transferase center on the ribosome. Almost all known resistance mechanisms involve small alterations to the linezolid binding site, so this review will therefore focus on the various changes that can adversely affect drug binding and confer resistance. High-resolution structures of linezolid bound to the 50S ribosomal subunit show that it binds in a deep cleft that is surrounded by 23S rRNA nucleotides. Mutation of 23S rRNA has for some time been established as a linezolid resistance mechanism. Although ribosomal proteins L3 and L4 are located further away from the bound drug, mutations in specific regions of these proteins are increasingly being associated with linezolid resistance. However, very little evidence has been presented to confirm this. Furthermore, recent findings on the Cfr methyltransferase underscore the modification of 23S rRNA as a highly effective and transferable form of linezolid resistance. On a positive note, detailed knowledge of the linezolid binding site has facilitated the design of a new generation of oxazolidinones that show improved properties against the known resistance mechanisms.
Immobilization of Antibacterial Dihydropyrrol-2-ones on Functional Polymer Supports To Prevent Bacterial Infections
In Vivo
Authors: Ho Kitty Ka Kit , Cole Nerida , Chen Renxun , Willcox Mark D. P. , Rice Scott A. , Kumar Naresh 
Published: December 2011

ABSTRACT

Antibiotic-resistant
Staphylococcus aureus
is of great concern, as it causes a wide range of life-threatening infections. The current study demonstrates that dihydropyrrolone (DHP)-coated polyacrylamide substrates are effective in reducing the number of culturable clinical isolates of
S. aureus
in vitro
in a dose-dependent manner and are able to reduce the pathogenic potential of staphylococcal infection in a subcutaneous infection model. Covalently bound DHPs therefore show great potential for use as an antimicrobial strategy in device-related applications.
Live Attenuated Salmonella Vaccines Displaying Regulated Delayed Lysis and Delayed Antigen Synthesis To Confer Protection against Mycobacterium tuberculosis
Authors: Juárez-Rodríguez María Dolores , Yang Jiseon , Kader Rebin , Alamuri Praveen , Curtiss Roy , Clark-Curtiss Josephine E. 
Published: December 2011

ABSTRACTLive recombinant attenuatedSalmonellavaccine (RASV) strains have great potential to induce protective immunity againstMycobacterium tuberculosisby deliveringM. tuberculosisantigens. Recently, we reported that, in orally immunized mice, RASV strains delivering theM. tuberculosisearly secreted antigenic target 6-kDa (ESAT-6) protein and culture filtrate protein 10 (CFP-10) antigens via theSalmonellatype III secretion system (SopE amino-terminal region residues 1 to 80 with two copies of ESAT-6 and one copy of CFP-10 [SopENt80-E2C]) afforded protection against aerosol challenge withM. tuberculosis. Here, we constructed and evaluated an improvedSalmonellavaccine againstM. tuberculosis. We constructed translational fusions for the synthesis of two copies of ESAT-6 plus CFP-10 fused to the OmpC signal sequence (OmpCSS-E2C) and amino acids 44 to 338 of antigen 85A (Ag85A294) flanked by the signal sequence (SS) and C-terminal peptide (CT) of β-lactamase (BlaSS-Ag85A294-BlaCT) to enable delivery via theSalmonellatype II secretion system. The genes expressing these proteins were cloned as an operon transcribed from Ptrcinto isogenic Asd+/MurA+pYA3681 lysis vector derivatives with different replication origins (pBR, p15A, pSC101), resulting in pYA4890, pYA4891, and pYA4892 for SopENt80-E2C/Ag85A294synthesis and pYA4893 and pYA4894 for OmpCSS-E2C/Ag85A294synthesis. Mice orally immunized with the RASV χ11021 strain engineered to display regulated delayed lysis and regulated delayed antigen synthesisin vivoand harboring pYA4891, pYA4893, or pYA4894 elicited significantly greater humoral and cellular immune responses, and the RASV χ11021 strain afforded a greater degree of protection againstM. tuberculosisaerosol challenge in mice than RASVs harboring any other Asd+/MurA+lysis plasmid and immunization withM. bovisBCG, demonstrating that RASV strains displaying regulated delayed lysis with delayed antigen synthesis resulted in highly immunogenic delivery vectors for oral vaccination againstM. tuberculosisinfection.
Sialylation of Lipooligosaccharides Is Dispensable for the Virulence of Haemophilus ducreyi in Humans
Authors: Spinola Stanley M. , Li Wei , Fortney Kate R. , Janowicz Diane M. , Zwickl Beth , Katz Barry P. , Munson Robert S. 
Published: December 2011

ABSTRACT

Sialylated glycoconjugates on the surfaces of mammalian cells play important roles in intercellular communication and self-recognition. The sialic acid preferentially expressed in human tissues is
N
-acetylneuraminic acid (Neu5Ac). In a process called molecular mimicry, many bacterial pathogens decorate their cell surface glycolipids with Neu5Ac. Incorporation of Neu5Ac into bacterial glycolipids promotes bacterial interactions with host cell receptors called Siglecs. These interactions affect bacterial adherence, resistance to serum killing and phagocytosis, and innate immune responses.
Haemophilus ducreyi
, the etiologic agent of chancroid, expresses lipooligosaccharides (LOS) that are highly sialylated. However, an
H. ducreyi
sialyltransferase (
lst
) mutant, whose LOS contain reduced levels of Neu5Ac, is fully virulent in human volunteers. Recently, a second sialyltransferase gene (
Hd0053
) was discovered in
H. ducreyi
, raising the possibility that
Hd0053
compensated for the loss of
lst
during human infection. CMP-Neu5Ac is the obligate nucleotide sugar donor for all bacterial sialyltransferases; LOS derived from an
H. ducreyi
CMP-Neu5Ac synthetase (
neuA
) mutant has no detectable Neu5Ac. Here, we compared an
H. ducreyi neuA
mutant to its wild-type parent in several models of pathogenesis. In human inoculation experiments, the
neuA
mutant formed papules and pustules at rates that were no different than those of its parent. When grown in media with and without Neu5Ac supplementation, the
neuA
mutant and its parent had similar phenotypes in bactericidal, macrophage uptake, and dendritic cell activation assays. Although we cannot preclude a contribution of LOS sialylation to ulcerative disease, these data strongly suggest that sialylation of LOS is dispensable for
H. ducreyi
pathogenesis in humans.
Effects of Amino Acid Supplementation on Porin Expression and ToxR Levels in Vibrio cholerae
Authors: Mey Alexandra R. , Craig Stephanie A. , Payne Shelley M. 
Published: December 2011

ABSTRACT

Vibrio cholerae
responds to environmental changes by altering the protein composition of its outer membrane. In rich medium,
V. cholerae
expresses almost exclusively the outer membrane porin OmpU, whereas in minimal medium, OmpT is the dominant porin. The supplementation of a minimal medium with a mixture of asparagine, arginine, glutamic acid, and serine (NRES) promotes OmpU production and OmpT repression at levels similar to those seen with rich media. Here we show that the altered Omp profile is not due to an increase in the growth rate in the presence of supplemental amino acids but requires the addition of specific amino acids. The effects of the NRES mix on Omp production were mediated by ToxR, a known regulator of
omp
gene expression. No changes in the Omp profile were detected in a
toxR
mutant. Supplementation with the NRES mix resulted in significantly higher levels of ToxR, and the elevated ToxR levels were sufficient to cause a switch in Omp synthesis. The increase in the level of the ToxR protein correlated with an increase in
toxR
mRNA levels and was observed only when
toxR
was expressed from its native promoter. ToxS, which is required for ToxR activity, was necessary for NRES-mediated
omp
gene regulation but not for the increase in ToxR levels. The growth of
V. cholerae
in the presence of bile acids also resulted in Omp switching, and this required ToxR. However, unlike the NRES mix, bile acids did not increase either ToxR protein or
toxR
mRNA levels, suggesting a different mechanism of
omp
gene regulation by bile than that by amino acids.
The epidemiology of new versus recurrent sports concussions among high school athletes, 2005–2010
Authors: Castile Lianne , Collins Christy L , McIlvain Natalie M , Comstock R Dawn 
Published: December 2011

ObjectivesTo compare new versus recurrent concussions with respect to constellation of symptoms, symptom severity, symptom resolution; evaluate potential subset differences with respect to gender and sport; and to compare mechanisms and activities associated with new versus recurrent concussions.MethodsSports-related injury and exposure data were collected for nine sports from 2005 to 2010 from 100 nationally representative US high schools.ResultsNationally, an estimated 732,805 concussions occurred. Of these reported concussions, 13.2% were recurrent. The rate of new concussions was 22.2 per 100,000 athletic exposures while the rate of recurrent concussions was 3.1 per 100,000 athletic exposures (RR 7.23, 95% CI 6.39 to 8.17, p<0.001). While 0.6% of new concussion symptoms took >1 month to resolve, 6.5% of recurrent concussion symptoms took >1 month to resolve (IPR 10.35; 95% CI 4.62 to 23.16; p<0.001). Loss of consciousness was reported more often with recurrent (7.7%) than new concussions (4.4%) (IPR 1.76; 95% CI 1.02 to 3.03; p=0.043). A greater proportion of athletes sustaining recurrent concussions returned to play in >3 weeks (7.5%) or were medically disqualified (16.2%) than athletes sustaining new concussions (3.8%; IPR 1.95; 95% CI 1.01 to 3.77; p=0.047 and 2.9%; IPR 5.58; 95% CI 3.50 to 8.88; p<0.001, respectively). The majority of new and recurrent concussions resulted from contact with another person (73.4% and 77.9%, respectively).ConclusionsAthletes sustaining recurrent concussions had longer symptom resolution times, were kept out of play longer and reported loss of consciousness more frequently than athletes sustaining new concussions. With the possibility of long-term impairment and other negative sequelae, proper management and prevention of concussions at the high school level is imperative.
Which domains of childhood physical activity predict physical activity in adulthood? A 20-year prospective tracking study
Authors: Cleland Verity , Dwyer Terence , Venn Alison 
Published: December 2011

PurposeIt is important to examine how childhood physical activity is related to adult physical activity in order to best tailor physical activity-promotion strategies. The time- and resource-intensive nature of studies spanning childhood into adulthood means the understanding of physical activity trajectories over this time span is limited. This study aimed to determine whether childhood domain-specific physical activities predict domain-specific physical activity 20 years later in adulthood, and whether age and sex play a role in these trajectories.MethodsIn 1985, 6412 children of age 9–15 years self-reported frequency and duration of discretionary sport and exercise (leisure activity), transport activity, school sport and physical education (PE) in the past week and number of sports played in the past year. In 2004–2006, 2201 of these participants (aged 26–36 years) completed the long International Physical Activity Questionnaire and/or wore a Yamax pedometer. Analyses included partial correlation coefficients and log-binomial regression.ResultsChildhood and adult activity were weakly correlated (r=−0.08–0.14). Total weekly physical activity in childhood did not predict adult activity. School PE predicted adult total weekly physical activity and daily steps (older females), while school sport demonstrated inconsistent associations. Leisure and transport activity in childhood predicted adult leisure activity among younger males and older females, respectively. Childhood past year sport participation positively predicted adult physical activity (younger males and older females).ConclusionsDespite modest associations between childhood and adult physical activity that varied by domain, age and sex, promoting a range of physical activities to children of all ages is warranted.