537 research outputs found
Synthesis of nanocrystalline TiO2 thin films by liquid phase deposition technique and its application for photocatalytic degradation studies
A transparent, high purity titanium dioxide thin film composed of densely packed nanometer sized grains has been successfully deposited on a glass substrate at 30°C from an aqueous solution of TiO2-HF with the addition of boric acid as a scavenger by liquid phase deposition technique. From X-ray diffraction measurement, the deposited film was found to be amorphous and turns crystalline at 500°C. The deposited film showed excellent adherence to the substrate and was characterized by homogeneous flat surface. TiO2 thin films can be used as a photocatalyst to clean up organohalides, a class of compound in pesticides that pollute the ground water. Photocatalytic degradation experiments show that indanthrene golden orange dye undergoes degradation efficiently in presence of TiO2 thin films by exposing its aqueous solution to ultraviolet light. The suitable surface structure and porosity increases the photocatalytic activity. It was also observed that hemin doped TiO2 thin films break up organohalides at a surprisingly high rate under visible light
Effects of Ni doping on photocatalytic activity of TiO(2) thin films prepared by liquid phase deposition technique
The TiO(2) thin films doped by Ni uniformly and non-uniformly were prepared on glass substrate from an aqueous solution of ammonium hexa-fluoro titanate and NiF(2) by liquid phase deposition technique. The addition of boric acid as an F(-) scavenger will shift the equilibrium to one side and thereby deposition of the film is progressed. The rate of the reaction and the nature of deposition depend on growing time and temperature. The resultant films were characterized by XRD, EDAX, UV and SEM. The result shows that the deposited films have amorphous background, which becomes crystalline at 500 degrees C. The EDAX data confirms the existence of Ni atoms in TiO(2) matrix. XRD analysis reveals the peaks corresponding to Ni but no peak of crystalline NiO was found. The transmittance spectra of Ni uniformly and non-uniformly doped TiO(2) thin films show 'blue shift and red shift', respectively. Ni-doped TiO(2) thin films can be used as photocatalyst for the photodegradation of methyl orange dye. It was found that, organic dye undergoes degradation efficiently in presence of non-uniformly Ni-doped TiO(2) thin films when compared to uniformly doped films and pure TiO(2) films under visible light. The photocatalytic activity increases with increase in the concentration of Ni in case of nonuniformly doped thin films but decreases with the concentration when uniformly doped thin films were used
Polarized deep inelastic scattering at high energies and parity violating structure functions
A comprehensive analysis of deep inelastic scattering of polarized charged
leptons on polarized nucleons is presented; weak interaction contributions,
both in neutral and charged current processes, are taken into account and the
parity violating polarized nucleon structure functions are studied. Possible
ways of their measurements and their interpretations in the parton model are
discussed.Comment: (slightly modified version, includes a few new references and
corrects few misprints for publication), 14 pages in TeX (needs harvmac) no
figure, DFTT 80/9
Franck-Condon Effect in Central Spin System
We study the quantum transitions of a central spin surrounded by a
collective-spin environment. It is found that the influence of the
environmental spins on the absorption spectrum of the central spin can be
explained with the analog of the Franck-Condon (FC) effect in conventional
electron-phonon interaction system. Here, the collective spins of the
environment behave as the vibrational mode, which makes the electron to be
transitioned mainly with the so-called "vertical transitions" in the
conventional FC effect. The "vertical transition" for the central spin in the
spin environment manifests as, the certain collective spin states of the
environment is favored, which corresponds to the minimal change in the average
of the total spin angular momentum.Comment: 8 pages, 8 figure
Delineating Zinc Influx Mechanisms during Platelet Activation
Zinc (Zn2+) is released by platelets during a hemostatic response to injury. Extracellular zinc ([Zn2+]o) initiates platelet activation following influx into the platelet cytosol. However, the mechanisms that permit Zn2+ influx are unknown. Fluctuations in intracellular zinc ([Zn2+]i) were measured in fluozin-3-loaded platelets using fluorometry and flow cytometry. Platelet activation was assessed using light transmission aggregometry. The detection of phosphoproteins was performed by Western blotting. [Zn2+]o influx and subsequent platelet activation were abrogated by blocking the sodium/calcium exchanged, TRP channels, and ZIP7. Cation store depletion regulated Zn2+ influx. [Zn2+]o stimulation resulted in the phosphorylation of PKC substates, MLC, and β3 integrin. Platelet activation via GPVI or Zn2+ resulted in ZIP7 phosphorylation in a casein kinase 2-dependent manner and initiated elevations of [Zn2+]i that were sensitive to the inhibition of Orai1, ZIP7, or IP3R-mediated pathways. These data indicate that platelets detect and respond to changes in [Zn2+]o via influx into the cytosol through TRP channels and the NCX exchanger. Platelet activation results in the externalization of ZIP7, which further regulates Zn2+ influx. Increases in [Zn2+]i contribute to the activation of cation-dependent enzymes. Sensitivity of Zn2+ influx to thapsigargin indicates a store-operated pathway that we term store-operated Zn2+ entry (SOZE). These mechanisms may affect platelet behavior during thrombosis and hemostasis
Bariatric surgery for spontaneous ovulation in women living with polycystic ovary syndrome: the BAMBINI multicentre, open-label, randomised controlled trial
BackgroundPolycystic ovary syndrome (PCOS) is the most common cause of an ovulatory infertility. Obesity exacerbates the reproductive complications of PCOS; however, the management of obesity in women with PCOS remains a large unmet clinical need. Observational studies have indicated that bariatric surgery could improve the rates of ovulatory cycles and prospects of fertility; however, the efficacy of surgery on ovulation rates has not yet been compared with behavioural modifications and medical therapy in a randomised trial. The aim of this study was to compare the safety and efficacy of bariatric surgery versus medical care on ovulation rates in women with PCOS, obesity, and oligomenorrhoea or amenorrhoea.MethodsIn this multicentre, open-label, randomised controlled trial, 80 women older than 18 years, with a diagnosis of PCOS based on the 2018 international evidence-based guidelines for assessing and managing PCOS, and a BMI of 35 kg/m2 or higher, were recruited from two specialist obesity management centres and via social media. Participants were randomly assigned at a 1:1 ratio to either vertical sleeve gastrectomy or behavioural interventions and medical therapy using a computer-generated random sequence (PLAN procedure in SAS) by an independent researcher not involved with any other aspect of theclinical trial. The median age of the entire cohort was 31 years and 79% ofparticipants were White. The primary outcome was the number of biochemicallyconfirmed ovulatory events over 52 weeks, and was assessed using weekly serumprogesterone measurements. The primary endpoint included the intention-to-treatpopulation and safety analyses were per-protocol population. This study isregistered with the ISRCTN registry (ISRCTN16668711).FindingsParticipants were recruited from Feb 20, 2020 to Feb 1, 2021.40 participants were assigned to each group and there were seven dropouts in the medical group and ten dropouts in the surgical group. The median number of ovulations was 6 (IQR 3·5–10·0) in the surgical group and 2 (0·0–4·0) in the medical group. Women in the surgical group had 2.5 times more spontaneous ovulations compared with the medical group (incidence rate ratio 2·5 [95% CI1·5–4·2], p<0·0007). There were more complications in the surgical group than the medical group, although without long-term sequelae. There were 24(66·7%) adverse events in the surgical group and 12 (30·0%) in the medical group. There were no treatment-related deaths.InterpretationBariatric surgery was more effective than medical care for the induction of spontaneous ovulation in women with PCOS, obesity, and oligomenorrhoea or amenorrhoea. Bariatric surgery could, therefore, enhance the prospects of spontaneous fertility in this group of women.</p
Exploring a community's understanding of HIV vaccine-induced seropositivity in a South African research setting
BACKGROUND. The high HIV prevalence and incidence in South Africa makes it suitable for recruitment of participants for large-scale HIV
preventive vaccine trials. However, fear of vaccine-induced seropositivity (VISP) may be a barrier for community acceptability of the trial,
for volunteers to participate in HIV preventive vaccine trials and for uptake of an efficacious vaccine. Prior to 2015, when the first phase
1 safety HIV vaccine trial was undertaken at Setshaba Research Centre, Soshanguve, the local community stakeholders and healthcare
workers were naive about HIV vaccine research and HIV preventive vaccines.
OBJECTIVE. To explore knowledge and perceptions regarding VISP among community stakeholders and healthcare workers in peri-urban
Soshanguve, Tshwane.
METHODS. Using a quantitative-qualitative mixed-methods study design, surveys (n=50) and in-depth interviews (n=18) were conducted during
July - August 2015. Participants included community stakeholders, community advisory board members and healthcare workers, who were
>18 years old and had attended community educational workshops during September 2014 - May 2015. Audio recordings of interviews were
transcribed verbatim and coded using content thematic analysis. Data were further analysed by sex, age and educational level.
RESULTS. Of a maximum score of 2 on knowledge on VISP, the 50 survey participants (mean age 33.78 years; 45 females) obtained an
average of 0.88 (44%). Of 17 in-depth interviewees (one interview could not be transcribed; mean age 30.9 years; 12 females), 8 (47%)
displayed some knowledge about VISP, of whom only 5 defined VISP correctly. Women were more knowledgeable about VISP than men;
5 of 12 women (42%) came close to defining VISP correctly, while none of the 5 men did so. The main fear of trial participation expressed
by most participants (n=6) was testing HIV-positive as a result of the vaccine. While some participants believed that the community’s
perceptions of VISP would negatively affect HIV vaccine trial support and recruitment efforts, others noted that if trial participants
understand the concept of VISP and are part of support groups, then they would have the information to combat negative attitudes within
their community.
CONCLUSION. Most participants had an inaccurate and incomplete understanding of VISP. Many feared testing HIV-positive at clinics;
therefore, education on improving a basic understanding of how vaccines work and why VISP occurs is essential. In addition, assessing
participant understanding of HIV testing, transmission and VISP is critical for recruitment of participants into HIV vaccine trials and may
improve acceptability of an HIV preventive vaccine.The National Institute of Allergy and Infectious Diseases (NIAID) US Public Health Service.https://journals.co.za/journal/m.samjam2024Medical MicrobiologyNon
Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS
We present the results of a search for new, heavy particles that decay at a
significant distance from their production point into a final state containing
charged hadrons in association with a high-momentum muon. The search is
conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV
and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS
detector operating at the Large Hadron Collider. Production of such particles
is expected in various scenarios of physics beyond the standard model. We
observe no signal and place limits on the production cross-section of
supersymmetric particles in an R-parity-violating scenario as a function of the
neutralino lifetime. Limits are presented for different squark and neutralino
masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final
version to appear in Physics Letters
Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment
This paper describes an analysis of the angular distribution of W->enu and
W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with
the ATLAS detector at the LHC in 2010, corresponding to an integrated
luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and
the missing transverse energy, the W decay angular distribution projected onto
the transverse plane is obtained and analysed in terms of helicity fractions
f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV
and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw
> 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour,
are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017
+/- 0.030, where the first uncertainties are statistical, and the second
include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables,
revised author list, matches European Journal of Physics C versio
Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS
The chi_b(nP) quarkonium states are produced in proton-proton collisions at
the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS
detector. Using a data sample corresponding to an integrated luminosity of 4.4
fb^-1, these states are reconstructed through their radiative decays to
Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks
corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new
structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is
also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes.
This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table,
corrected author list, matches final version in Physical Review Letter
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