35 years since identification of HIV as the causative agent of AIDS, and 35 million deaths associated with this disease, significant effort is now directed towards the development of potential cures. ...Current anti-retroviral (ART) therapies for HIV/AIDS can suppress virus replication to undetectable levels, and infected individuals can live symptom free so long as treatment is maintained. However, removal of therapy allows rapid re-emergence of virus from a highly stable reservoir of latently infected cells that exist as a barrier to elimination of the infection with current ART. Prospects of a cure for HIV infection are significantly encouraged by two serendipitous cases where individuals have entered remission following stem cell transplantation from compatible HIV-resistant donors. However, development of a routine cure that could become available to millions of infected individuals will require a means of specifically purging cells harboring latent HIV, preventing replication of latent provirus, or destruction of provirus genomes by gene editing. Elimination of latently infected cells will require a means of exposing this population, which may involve identification of a natural specific biomarker or therapeutic intervention to force their exposure by reactivation of virus expression. Accordingly, the proposed “Shock and Kill” strategy involves treatment with latency-reversing agents (LRA) to induce HIV provirus expression thus exposing these cells to killing by cellular immunity or apoptosis. Current efforts to enable this strategy are directed at developing improved combinations of LRA to produce broad and robust induction of HIV provirus and enhancing the elimination of cells where replication has been reactivated by targeted immune modulation. Alternative strategies may involve preventing re-emergence virus from latently infected cells by “Lock and Block” intervention, where transcription of provirus is inhibited to prevent virus spread or disruption of the HIV provirus genome by genome editing.
With an ever-increasing number of applications in many advanced fields, gas sensors are becoming indispensable devices in our daily life. Among different types of gas sensors, conductometric metal ...oxide semiconductor (MOS) gas sensors are found to be the most appealing for advanced applications in the automotive, biomedical, environmental, and safety sectors because of the their high sensitivity, reduced size, and low cost. To improve their sensing characteristics, new metal oxide-based nanostructures have thus been proposed in recent years as sensing materials. In this review, we extensively review gas-sensing properties of core@ shell nanocomposites in which metals as the core and metal oxides as the shell structure, both of nanometer sizes, are assembled into a single metal@metal oxide core–shell. These nanostructures not only combine the properties of both noble metals and metal oxides, but also bring unique synergetic functions in comparison with single-component materials. Up-dated achievements in the synthesis and characterization of metal@metal oxide core–shell nanostructures as well as their use in MOS sensors are here reported with the main objective of providing an overview about their gas-sensing properties.
Stainless steel 316L is one of the most common biomaterials utilized for producing orthopedic implants. But it has low resistance to fatigue and wear. Therefore surface treatments such as shot ...peening are used to modify the surface properties. In the present research, the influence of shot peening treatment on hardness, fatigue and corrosion behavior of 316L stainless steel in Ringer's solution was investigated. For this purpose, the steel specimens were shot peened for 5, 10, 15, 20 and 25
min. Hardness, fatigue and electrochemical tests were performed on each specimen before and after shot peening treatment. The open circuit potential (OCP) of the specimens, after 2
h of equilibrium time, was measured in Ringer's solution for 300
s. The cyclic potentiodynamic polarization tests were performed with 5
mV/s scan rate. According to the results, the shot peening treatment increases the surface hardness and fatigue resistance. In addition, this treatment decreases the break-down potential of the passive layer and increases the corrosion current density in shot peened specimens up to 10
min, which shows a reduction in resistance to pitting corrosion. However, the break-down potential of the passive layer begins to increase and the corrosion current density decreases at upper times. This trend continues such that even the conditions of resistance to pitting corrosion improve in comparison with un-shot peened specimens at longer times of shot peening. The morphology of the fractured surfaces of samples was investigated by scanning electron microscopy (SEM).
► Decreasing mean particle size from 82 to 56
nm with increasing the Sn–Mg proportion from
x
=
0.0 to
x
=
0.8. ► Reducing the coercivity from 4728.9 to 1455.5
Oe and increasing the saturation ...magnetization from 51.34 to 65.49
emu/g with increasing the Sn–Mg from
x
=
0.0 to
x
=
0.8. ► The higher effective electromagnetic absorption properties for strontium hexaferrite–acrylic resin composites which contained doped hexaferrite with
x
=
0.8.
Nanoparticles of Sn–Mg substituted strontium hexaferrite with the composition of SrFe
12−
x
(Sn
0.5 Mg
0.5)
x
O
19 (
x
=
0.0–1.0) were synthesized by chemical coprecipitation method. Deionized water/ethanol (50/50) was used as the solvent. The single phase strontium hexaferrites were obtained at pH 13 and Fe
3+/Sr
2+ molar ratio of 9 after calcination at 800
°C. The mean particle size of samples was decreased from 82 to 56
nm with increasing the Sn–Mg content from
x
=
0.0 to
x
=
0.8. The effect of Sn–Mg substitution on magnetic properties of hexaferrites was studied using vibrating-sample magnetometer. It was found that increasing the Sn–Mg from
x
=
0.0 to
x
=
0.8 reduced the coercivity from 4728.9 to 1455.5
Oe and increased the saturation magnetization from 51.34 to 65.49
emu/g. A vector network analyzer was used to investigate the microwave absorption properties. According to microwave measurements, doped strontium hexaferrite composites had much more effective electromagnetic absorption properties than undoped strontium hexaferrite composite.
This paper aims at studying the effect of the particle size on the compression and tension behavior of the cobalt ferrite-based magnetorheological fluid (MRF). To achieve this goal, Co–ferrite ...nano-particles (CoFe2O4) with three different sizes, were synthesized by the chemical co-precipitation method and then two of them were mixed together. The X-Ray Diffraction (XRD) analysis, Scattering Electron Microscope (SEM), Laser Particle Size Analysis (LPSA) and Vibrating Sample Magnetometer (VSM) were carried out to study the phase analysis, particles morphology, particle distribution and magnetic properties, respectively. Then the compression and tension tests were conducted on MRFs containing silicon oil as a carrier. The results showed that the highest values of the compression and tension strengths of fluids correspond to the larger particle sizes (550nm) with 1.241 and 0.594MPa, respectively. Furthermore, the compression and tension strengths of the mixed one (1.153 and 0.388MPa) containing 60 and 300nm samples are higher than its components with 0.431 and 0.249MPa, as well as 0.694 and 0.367MPa, respectively.
•Co–ferrite particles with three different sizes were obtained by co-precipitation.•Two of these different-sized solid particles were mixed to make the fourth sample.•Four Co–ferrite MRFs were prepared and compression/tension tests were conducted.•The bigger particle-sized MRFs show higher maximum compression/tension strengths.•The maximum strengths of the mixed sample MRF are higher than MRFs of its components.
We summarize the science opportunity, design elements, current and projected partner observatories, and anticipated science returns of the Astrophysical Multimessenger Observatory Network (AMON). ...AMON will link multiple current and future high-energy, multimessenger, and follow-up observatories together into a single network, enabling near real-time coincidence searches for multimessenger astrophysical transients and their electromagnetic counterparts. Candidate and high-confidence multimessenger transient events will be identified, characterized, and distributed as AMON alerts within the network and to interested external observers, leading to follow-up observations across the electromagnetic spectrum. In this way, AMON aims to evoke the discovery of multimessenger transients from within observatory subthreshold data streams and facilitate the exploitation of these transients for purposes of astronomy and fundamental physics. As a central hub of global multimessenger science, AMON will also enable cross-collaboration analyses of archival datasets in search of rare or exotic astrophysical phenomena.
Background/significance Salmonella gastroenteritis causes significant morbidity among pediatric patients, mainly in developing world, such as the Middle East and North Africa (MENA) region. ...Concurrently, data from MENA countries like Iran, regarding prevalence of Salmonella serotypes, antimicrobial susceptibility, and biofilm production is scarce. Material & methods Slide agglutination was used to determine the serogroup of 140 Salmonella isolates recovered from 4477 stool specimens collected from children with gastroenteritis, and isolates were serotyped by PCR assay. The antimicrobial susceptibility of isolates to five first line drugs was assessed by disk diffusion assay using CLSI guidelines. Semi-quantitative evaluation of biofilm production was done by microtiter plate assay followed by PCR detection of biofilm-associated virulence genes csgD, pefA, and bcsA for each isolate. Results Nearly 94% of Salmonella isolates were recovered from less than or equai to 5-year-old patients, and 99% of isolates were non-typhoidal. While we found extensive diversity among Salmonella isolates, serogroup D (46%) predominated, and Salmonella Enteritidis (41%) was the most common serotype that showed the highest antimicrobial susceptibility rate (> 96%). For the first time in Iran, S. Newport serotype from human specimens was isolated. Most isolates were sensitive to all test antimicrobials, but 35% of isolates were not-typed (NT) that showed the highest resistance with 48% being resistant to greater than or equal to 1 test antimicrobial. Majority of isolates made weak (or no) biofilm, and we found a weak association between antimicrobial susceptibility, biofilm production, or virulence genes csgD, pefA, and bcsA. Conclusions The most effective measure that may control pediatric salmonellosis outbreaks is raising awareness of parents of preschoolers about food safety. Isolation of highly diverse Salmonella serotypes, including many commonly isolated from animals, indicates widespread contamination of the food chain. Majority of serotypes were sensitive to first-line antimicrobials, thus presently, pediatric Salmonella infections in this region may be controlled by conventional antimicrobials. However, despite the current trend, an imminent emergence of resistant Salmonella strains is foreseen, since various serotypes resistant to > 1 antimicrobial agent are typically associated with animals. Our results warrant further investigation that includes correlation analysis of clinical data regarding treatment outcomes, and serotype attributes like virulence genes. Keywords: Salmonella serogroups, Serotypes, Antimicrobial susceptibility, Biofilm, Virulence genes
Densification, grain growth and magnetic properties of Li-Zn ferrite (Li.30Zn.4Fe2.30O4) doped with B2O3 as a sintering aid were investigated. B2O3 is a low melting point (460 degree C) oxide and ...forms a liquid phase during sintering which affects the densification and grain growth of ferrites. Results showed that density and grain growth rate were sensitive to the B2O3 content and sintering temperature. At low amounts of B2O3 (<1wt.%), an increase in the B2O3 content increased density and grain growth rate. The highest density and the maximum magnetization were obtained for the sample containing 1.0wt.% B2O3 which was sintered at a lower temperature (1000 degree C) for 1.5h, in comparison with undoped samples. Higher B2O3 contents than 1.0wt.% caused a decrease in density of samples due to secondary phases formation and evaporation of B2O3. The sample with the highest grain size showed the highest permeability and the lowest magnetic loss.
Understanding the mechanisms of HIV proviral latency is essential for development of a means to eradicate infection and achieve a cure. We have previously described an in vitro latency model that ...reliably identifies HIV expression phenotypes of infected cells using a dual-fluorescence reporter virus. Our results have demonstrated that ∼50% of infected cells establish latency immediately upon integration of provirus, a phenomenon termed early latency, which appears to occur by mechanisms that are distinct from epigenetic silencing observed with HIV provirus that establishes productive infections. In this study, we have used a mini-dual HIV reporter virus (mdHIV) to compare the long-term stability of provirus produced as early latent or productive infections using Jurkat-Tat T cell clones. Cloned lines bearing mdHIV provirus integrated at different chromosomal locations display unique differences in responsiveness to signaling agonists and chromatin-modifying compounds, and they also produce characteristic expression patterns from the 5' long terminal repeat (LTR) dsRed and internal EIF1α-enhanced green fluorescent protein (EIF1α-eGFP) reporters. Furthermore, reporter expression profiles of single cell sorted subcultures faithfully reproduce expression profiles identical to that of their original parental population, following prolonged growth in culture, without shifting toward expression patterns resembling that of cell subclones at the time of sorting. Comparison of population dispersion coefficient (CV) and mean fluorescence intensity (MFI) of the subcloned lines showed that both untreated and phorbol myristate acetate (PMA)-ionomycin-stimulated cultures produce expression patterns identical to those of their parental lines. These results indicate that HIV provirus expression characteristics are strongly influenced by the epigenetic landscape at the site of chromosomal integration.
There is currently considerable interest in development of therapies to eliminate latently infected cells from HIV-infected patients on antiretroviral therapy. One proposed strategy, known as "shock and kill," would involve treatment with therapies capable of inducing expression of latent provirus, with the expectation that the latently infected cells could be killed by a host immune response or virus-induced apoptosis. In clinical trials, histone deacetylase (HDAC) inhibitors were shown to cause reactivation of latent provirus but did not produce a significant effect toward eliminating the latently infected population. Results shown here indicate that integration of HIV provirus at different chromosomal locations produces significant effects on the responsiveness of virus expression to T cell signaling agonists and chromatin-modifying compounds. Given the variety of phenotypes produced by integrated provirus, it is unlikely that any single potential shock-and-kill therapy will be effective toward purging the latently infected population.
Acinetobacter baumannii is a bacterium responsible for health care-associated infections, and it frequently develops multiple drug resistance (MDR). The prevalence of antibiotic-resistant A. ...baumannii in Iran has increased, and this may cause significant clinical problems. Therefore, in order to elucidate the development of antibiotic resistance, we performed a systematic review of the literature published on antibiotic-resistant A. baumannii reported in Iran.
Thirty-six publications that met the criteria for inclusion were reviewed from an initial 87 papers. Selected papers published between 2008 and September 2014, were categorized on the basis of the sample collecting year been between 2001 and 2013.
Analysis of data revealed that, in general, there was an increase in antimicrobial resistance. During the initial time point of these studies (2001–2007) there was a high rate of resistance to all antibiotics, with the exception of carbapenems, lipopeptides, and aminoglycosides that had a low resistance rate in comparison with the others. Also, the resistance rate was increased in one group of these three antimicrobial groups from 2010 to 2013. In particular, there was an increase in resistance to carbapenems (imipenem and meropenem) from 2010–2011 and 2012–2013, whereas no significant change in the resistance rate of the other two antimicrobial groups (lipopeptides and aminoglycosides) during the study time was observed, although we did observe certain trends in amikacin (aminoglycoside group antibiotic) between 2011–2012 and 2012–2013.
These findings indicate that antimicrobial resistance of A. baumannii in Iran has increased, which may very well affect the antimicrobial resistance of this organism worldwide. Based on these results, novel prevention and treatment strategies against A. baumannii infections are warranted. Furthermore, these data may assist in revising treatment guidelines and regional policies in care units to slow the emergence of antimicrobial resistance.
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