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The molybdenum disulfide (MoS2) and indium tin oxide (ITO) interface were studied by atom probe tomography (APT). Raman spectroscopy, scanning electron microscopy, and grazing-incidence x-ray diffraction measurements were performed as complementary characterization. Results confirm that nanowires plated shape with the 〈110〉-orientation are aligned perpendicular to the ITO film with principal reflections at (002), (100), (101), (201), and Raman spectroscopy vibrational modes at E12g at 378 cm−1 and A1g at 407 cm−1 correspond to 2H-MoS2. APT reveals MoS+2, MoS+3 as predominant evaporated molecular ions on the sample, indicating no significant diffusion/segregation of Mo or S species within the ITO layer.
The necrocolous Coleoptera (attracted to carrion) are important to maintain balance in insect communities and in the recycling of soil nutrients; however, there is scarce data on the species that occur in Agave tequilana Weber (Asparagaceae) fields. The diversity patterns of beetles (Coleoptera: Scarabaeidae, Silphidae, and Trogidae) dwelling in 2–4-year-old A. tequilana plots were established by sampling specimens from May to November 2016. In total, 5509 individuals of 23 species were collected. The highest species diversity was found in Magdalena Municipality, followed by the Arandas and Tequila municipalities (Jalisco, Mexico), with significant differences in abundance among municipalities and crop age. The variability in Magdalena and Tequila assemblages was associated with the temperature, while in Arandas it was attributed to the precipitation. The beetle species diversity, species replacement, and dominance in different municipalities are the result of changes in habitat, the interaction of environmental variables, distribution affinities of species, and agronomic practices in A. tequilana fields.
To compare the epidemiology, clinical characteristics, and mortality of patients with bloodstream infections (BSI) caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (ESBL-EC) versus ESBL-producing Klebsiella pneumoniae (ESBL-KP) and to examine the differences in clinical characteristics and outcome between BSIs caused by isolates with CTX-M versus other ESBL genotypes
As part of the INCREMENT project, 33 tertiary hospitals in 12 countries retrospectively collected data on adult patients diagnosed with ESBL-EC BSI or ESBL-KP BSI between 2004 and 2013. Risk factors for ESBL-EC versus ESBL-KP BSI and for 30-day mortality were examined by bivariate analysis followed by multivariable logistic regression.
The study included 909 patients: 687 with ESBL-EC BSI and 222 with ESBL-KP BSI. ESBL genotype by polymerase chain reaction amplification of 286 isolates was available. ESBL-KP BSI was associated with intensive care unit admission, cardiovascular and neurological comorbidities, length of stay to bacteremia >14 days from admission, and a nonurinary source. Overall, 30-day mortality was significantly higher in patients with ESBL-KP BSI than ESBL-EC BSI (33.7% vs 17.4%; odds ratio, 1.64; P=.016). CTX-M was the most prevalent ESBL subtype identified (218 of 286 polymerase chain reaction-tested isolates, 76%). No differences in clinical characteristics or in mortality between CTX-M and non–CTX-M ESBLs were detected.
Clinical characteristics and risk of mortality differ significantly between ESBL-EC and ESBL-KP BSI. Therefore, all ESBL-producing Enterobacteriaceae should not be considered a homogeneous group. No differences in outcomes between genotypes were detected.
To determine the effects of lipid-based nutrient supplements (LNS) on children’s Hb, linear growth and development, compared with supplementation with micronutrient powder (MNP).
The study was a two-arm parallel-group randomized controlled trial, where participants received either LNS or MNP for daily consumption during 6 months. Supplements were delivered by staff at government-run health centres. Hb, anthropometric, motor development, language development and problem-solving indicators were measured by trained research assistants when children were 12 months of age.
The study was conducted in five rural districts in the Province of Ambo in the Department of Huánuco, Peru.
We enrolled 6-month-old children (n 422) at nineteen health centres.
Children who received LNS had a higher mean Hb concentration and lower odds of anaemia than those who received MNP. No significant differences in height-for-age, weight-for-height or weight-for-age Z-score, or stunting and underweight prevalence, were observed. Provision of LNS was associated with a higher pre-verbal language (gestures) score, but such effect lost significance after adjustment for covariates. Children in the LNS group had higher problem-solving task scores and increased odds of achieving this cognitive task than children in the MNP group. No significant differences were observed on receptive language or gross motor development.
LNS between 6 and 12 months of age increased Hb concentration, reduced anaemia and improved cognitive development in children, but showed no effects on anthropometric indicators, motor or language development.
Protected areas have been established historically in residual places where the potential for extractive uses is low, implying that places at risk are usually under-protected. Argentina is no exception, with few protected areas established in productive regions that are prone to conversion. Here, using reptiles as a study group and considering the most important human threats in north-western Argentina, we estimated priority conservation areas where we expect species to persist in the face of climate change and land conversion. Protected areas cover no more than 9% of the study region, but represent less than 15% of reptile distributions. There are great opportunities for improving the conservation status in the region by protecting only 8% more of north-western Argentina, with the level of species protection inside the protected area network increasing almost four-fold, reaching 43% of species distributions on average and 59% of the distributions of threatened reptiles. Fortunately, the highest diversity of reptiles in the region does not match the places targeted for agriculture expansion. Our findings suggest that future prioritization schemes should embrace other groups that are especially diverse in the Chaco ecoregion, which overlaps with our study area.
Ancient silver artifacts, when exposed to environments that contain sulfides (H2S), become tarnished and a black film is formed on the surface. The current study deals with the role of copper content and oxygen in the formation of tarnishing in the silver alloys 0.925, 0.800 and 0.720. An ammonium sulfide solution was used as an accelerator of the tarnishing process for different immersion conditions. The analysis of the tarnishing layer in silver alloys was performed by Raman Spectroscopy, Scanning Electron Microscopy - Energy Dispersive X-ray spectroscopy (SEM-EDS) and X-Ray Fluorescence (XRF). The formation of the tarnishing layer was found to be influenced by copper and oxygen contents. The corrosion products under the conditions studied were found to be mainly acanthite and jalpaite.
Glasses and glass-ceramics of the system Diopside [D, CaMgSi2O6] - Fluorapatite [FAp, Ca5(PO4)3F] were synthesized and characterized. The studied theoretical phase compositions were (wt%): 1) 70% D-30% FAp, 2) 60% D-40% FAp and 3) 80% D-20% FAp. The glass-ceramics were synthesized by isothermal treatment of the corresponding parent glasses at either 800, 900 or 1000 °C, with holding times of either 30 min, 2 h or 5 h at high temperature. The in vitro bioactivities of all materials were tested in Kokubo’s Simulated Body Fluid (SBF), for 21 days at pH = 7.4 and 37 °C. All materials were characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM/EDS). In all cases, the in vitro bioactivity increased with decreasing crystallization degree in the materials, which was likely due to an inhibitory effect of the structural changes occurring during thermal treatment of the glasses. This was more accentuated for long thermal treatments. After 21 days of soaking in the SBF, an apatite-like surface layer, with a Ca/P molar ratio close to 1.67, was formed in the case of the parent glass of composition 2. This was attributed to an enhancing effect of so-called “phase separation” phenomenon that took place during the synthesis of that particular glass. Lastly, the MgO content of the glasses made no clear difference on their in vitro bioactivity.
Hydroxyapatite [HAp, Ca5(PO4)3(OH)] was synthesized by chemical precipitation, using H3PO4 and Ca(OH)2 as chemical precursors. The precursors were slowly mixed in suitable proportions aiming to obtain Ca/P molar ratios of 1.5, 1.67 or 2.0 in the reacting suspension. This was followed by 21.5 h of aging. Both reaction and aging stages were carried out under an atmosphere of still ambient air and under continuous stirring, either at room temperature, 60 or 90 °C. The precipitates were characterized by ICP-AES and XRD. The results suggested that the most suitable Ca/P molar ratio for the production of pure phase HAp is Ca/P = 1.67, as long as the initial Ca(OH)2 particle size and/or the suspension pH are carefully controlled, especially when the synthesis is carried out above room temperature.
BaAl2Si2O8 and SrAl2Si2O8 were synthesized by solid-state reaction of stoichiometric mixtures of either BaCO3 or SrCO3 with coal fly ash and Al2O3. The mixtures were mechanically activated in an attrition mill for up to 12 h and then reaction-sintered at 900-1300 °C, aiming to promote the formation of BaAl2Si2O8 and SrAl2Si2O8 as well as the conversion from their hexagonal (Hexacelsian) into their monoclinic (Celsian) forms, which is associated with improved mechanical properties in the sintered materials. Especially in the case of SrAl2Si2O8, the formation of Celsian was favored at relatively low sintering temperatures by increasing milling time. Although only the SrAl2Si2O8 composition was fully converted into Celsian, the Hexacelsian to Celsian conversions obtained for the mechanically-activated BaAl2Si2O8 composition were significantly higher than those previously reported in the literature for this compound. This could be attributed to the use of coal fly ash as raw material, which contains mineralizers that promote the mentioned conversion.
Corrosion is a worldwide, crucial problem that strongly affects natural and industrial environments, in particular the oil and gas industry. Natural gas (NG) is a source of energy in industrial, residential, commercial and electric applications. The abundance of NG in many countries augurs a profitable situation for the vast energy industry. NG is considered friendlier to the environment and with lesser greenhouse gas emissions as compared with other fossil fuels. In the last years, shale gas is increasingly exploited in U.S. and Europe, applying a hydraulic fracturing technique, for releasing gas from the bed rock by injection of saline water, acidic chemicals and sand to the wells. Various critical sectors of the NG industry infrastructure suffer from several types of corrosion: steel casings of production wells and their drilling equipment; gas conveying pipelines including pumps and valves; plants for regasification of liquefied natural gas (LNG) and municipal networks of NG distribution to the consumers. Practical technologies that minimize or prevent corrosion include selection of corrosion resistant engineering materials, cathodic protection, corrosion inhibitors, and application of external and internal paints, coatings and linings. Mexico is undergoing an intense reform process of the energy sector, that involves its oil, NG and electricity industries. Typical cases of corrosion management in the NG industry are presented based on the authors experience and knowledge.
In this work, the deposition and photocatalytic response of V2O5 thin films modified with different amounts of Ag (Ag:V2O5) is reported. Films were deposited on glass and silicon substrates (100), using the pulsed laser deposition (PLD) technique. A high purity vanadium target, with a different number of silver pellets attached on it were used. Thin films were characterized by energy dispersive spectroscopy (EDS) to determine the elemental chemical composition; structural changes due to the addition of Ag were monitored by Raman spectroscopy; Optical microscopy was used to observe the surface morphology and UV-Vis spectroscopy was employed to determine optical properties. Photocatalytic response of the prepared films was studied through the degradation of a malachite green solution using a solar irradiation source.
Aluminum titanium oxynitride (TiAlNO) coatings were deposited on 316 steel substrates by the sputtering technique, varying the nitrogen flow from 2.5, 5, 7.5 to 10 sccm, and maintaining constant at 12 sccm the flow argon gas. We used targets of titanium and alumina with 99.995% purity. The hardness and tribological analyses were determined by Vickers microhardness and tribology (tribometer pin-disc), respectively. The results show that the coating with a nitrogen flow of 10 sccm had the lowest volumetric wear (2.047738693 mm3) and the maximum value of hardness (11.2 GPa). Analysis of X-ray diffraction evidenced the presence of three crystalline phases: Ti2N, Al2O3 and TiO2. It can be observed that by increasing the nitrogen flow, the portion of semi-Ti2N phase increases, Al2O3 decreases and TiO2 remains almost constant, and also producing a change in crystallographic orientation with reference to the Ti2N phase. Crystal grain sizes were estimated by X-ray diffraction Fourier line profile analysis using Warren–Averbach method. This analysis showed a grain size between 5 and 15 nm. Raman spectroscopy results show the presence of the TiO2 phase which corroborated the X-ray diffraction results.
Carbon nanotubes (CNTs) were synthesized by Chemical Vapor Deposition (CVD) from diethyl ether, butanol, hexane and ethyl acetate. A quartz tube with a stainless steel tube catalyst core with 0.019 m diameter and 0.6 m large formed the reactor. To avoid combustion, argon was used as the carrier gas. Time process ranged 30 to 60 min. The range of CNTs synthesis temperature was 680-850 °C for different precursors. Scanning Electron Microscopy micrographs have demonstrated tangled CNTs growth in all samples, thus presenting difficult length measurement. The CNTs diameters from diethyl ether are 45-200 nm, butanol diameter range from 55-230 nm, hexane diameter range is 50-130 nm and ethyl acetate range from 100 to 300 nm. Carbon content for all samples was higher than 93 %, CNTs from butanol showed carbon concentration up to 99%. FTIR, Raman and X-Ray Spectroscopies spectra for all samples demonstrated the characteristics signals present in carbon nanotubes. This research proposes a simple, effective and innovative method to synthesize CNTs by CVD on iron stainless steel catalyst in combination with diethyl ether, ethyl acetate, butanol and hexane as precursors by applying the principles of green chemistry, sustainability and its ease to be scaled.
Gold nanoparticles can be used as ultimate electrical materials for storing electrons or controlling their flow for the next generation nano-electronic devices. These particles are the core element of assemblies where the electrical current is reduced to the smallest possible since electrons are controlled one by one by using the Coulomb blockade phenomenon. We prepared colloidal gold nanoparticles beteween 4 and 15 nm and grafted them on a grafted organic monolayer (GOM) on silicon. GOM are highly ordered monolayers prepared by hydrosilylation of alkene molecules and subsequently modified with an amine group so that gold nanoparticles can be firmly immobilized on top of the layer. We discuss several electrical properties at a single electron level. Using the conductive tip of KPFM, we were also able to reveal the spontaneous charging behavior of the gold nanoparticles so that the local work function of a 10 nm gold nanoparticle is only 3.7 eV. By placing an STM tip above a nanoparticle, Coulomb blockade allows controlling the number of electrons simultaneously injected in the nanoparticle. This opens the way for new kinds of single electron memories or single electron transistors.
Glass-ceramics of eutectic composition in the wollastonite [W, CaO⋅SiO2]- tricalcium phosphate [TCP, β-Ca3(PO4)2] binary system were synthesized by using the glass-crystallization method. The parent glass was crystalized at 800-1300 °C for 0.5-5 h. The in vitro bioactivity of the synthesized glass-ceramics was tested in Kokubo’s Simulated Body Fluid (SBF) for 7-21 days, at pH = 7.4 and 37 °C. All materials were characterized by X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM/EDS). The results showed that metastable Apatite phase [Ap, Ca10(PO4)6O], plus W and TCP phases expected according to the binary phase diagram, were formed. Ap was the first phase formed at 900 °C/0.5 h, which was followed by formation of W phase at 900 °C/2 h and of TCP phase at 1200 °C/0.5 h. The relative proportion of the formed crystalline phases was a function of heat treatment temperature and time. A eutectic microstructure was obtained for the materials heat-treated at 1300 °C for 2 or 5 h. All glass-ceramics showed the formation of a hydroxyapatite (HAp)-like layer during the in vitro bioactivity tests. After 21 days of soaking in SBF, the samples treated at 1300 °C/5 h showed a behavior similar to that typically shown by Bioeutectic® material, while the materials heat-treated at lower temperatures tended to form denser HAp-like layers, with similar thicknesses but with higher Ca/P molar ratios.
The optical and structural properties of co-doped HfO2 thin films with rare earth trivalent ions prepared by ultrasonic spray pyrolysis technique, are reported. An arrangement of multi-layer (Si-SiO2-HfO2:Eu3+-HfO2:Tb3+-HfO2:Tm3+-SiO2) were deposited on silicon substrates at temperatures from 400 to 550°C, using acetyl acetonates as precursory reagents. A refractive index value of 2.1 was determined by spectral ellipsometry. The surface morphology was obtained by AFM measurements. For 50 to 550 nm thickness films, an average roughness value of ∼56.8 Å was obtained for different substrate temperatures and grown deposition times. EDS measurements showed the presence of hafnium, and rare earths dopants as elemental composition. XPS measurements demonstrated that hafnium and rare earths oxidation species are formed at hafnium dioxide thin films. Photoluminescence emission spectra of multi-layer structures present characteristic emission peaks associated with Tb+3, Eu3+, and Tm3+ dopants. The results presented above motivate us to consider that these multilayer structures could be appropriate to be used as a rare earth host to improve optical emission.
American cutaneous leishmaniasis (ACL) is a complex disease with a rich diversity of animal host species. This diversity imposes a challenge, since understanding ACL transmission requires the adequate identification of reservoir hosts, those species able to be a source of additional infections. In this study we present results from an ACL cross-sectional serological survey of 51 dogs (Canis familiaris), where we used diagnostic tests that measure dog's exposure to Leishmania spp. parasites. We did our research in Panamá, at a village that has undergone significant ecosystem level transformations. We found an ACL seroprevalence of 47% among dogs, and their exposure was positively associated with dog age and abundance of sand fly vectors in the houses of dog owners. Using mathematical models, which were fitted to data on the proportion of positive tests as function of dog age, we estimated a basic reproductive number (R0 ± s.e.) of 1·22 ± 0·09 that indicates the disease is endemically established in the dogs. Nevertheless, this information by itself is insufficient to incriminate dogs as ACL reservoirs, given the inability to find parasites (or their DNA) in seropositive dogs and previously reported failures to experimentally infect vectors feeding on dogs with ACL parasites.
As in other cultivated species, dormancy can be seen as a problem in cereal production, either due to its short duration or to its long persistence. Indeed, cereal crops lacking enough dormancy at harvest can be exposed to pre-harvest sprouting damage, while a long-lasting dormancy can interfere with processes that rely on rapid germination, such as malting or the emergence of a uniform crop. Because the ancestors of cereal species evolved under very diverse environments worldwide, different mechanisms have arisen as a way of sensing an appropriate germination environment (a crucial factor for winter or summer annuals such as cereals). In addition, different species (and even different varieties within the same species) display diverse grain morphology, allowing some structures to impose dormancy in some cereals but not in others. As in seeds from many other species, the antagonism between the plant hormones abscisic acid and gibberellins is instrumental in cereal grains for the inception, expression, release and re-induction of dormancy. However, the way in which this antagonism operates is different for the various species and involves different molecular steps as regulatory sites. Environmental signals (i.e. temperature, light quality and quantity, oxygen levels) can modulate this hormonal control of dormancy differently, depending on the species. The practical implications of knowledge accumulated in this field are discussed.
Although several meta-analyses have investigated the efficacy of psychological treatments for pediatric obsessive-compulsive disorder (OCD), there is not yet a consensus on the most efficacious treatment components. A meta-analysis was carried out to examine the efficacy of the different treatment techniques used in the psychological interventions of pediatric OCD. An exhaustive literature search from 1983 to February 2014 enabled us to locate 46 published articles that applied some kind of cognitive-behavioral therapy (CBT). For each group the effect size was the standardized pretest-posttest mean change, and it was calculated for obsessive-compulsive symptoms and for other outcome measures. The results clearly showed large effect sizes for CBT in reducing obsessive-compulsive symptoms and, to a lesser extent, other outcome measures (d+ = 1.860; 95% CI: 1.639; 2.081). The most promising treatments are those based on multicomponent programs comprising ERP, cognitive strategies, and relapse prevention. The analysis of other potential moderator variables and the implications for clinical practice are discussed.
The chemical synthesis of the copolymers poly(3-HT-co-EDOT-co-fluorene) and poly(3-HT-co-EDOT-co-TDR1) is reported. The first copolymer is derived of 3-hexylthiophene (3-HT), 3,4-ethylenedioxythiophene (EDOT) and 2,2'- (9,9-dioctyl-9H-fluorene-2,7-diyl) bisthiophene (fluorene). The second copolymer is derived of 3-hexylthiophene (3-HT), 3,4-ethylenedioxythiophene (EDOT) and (E)-2-(ethyl(4-((4-nitrophenyl)diazenyl)phenyl)amino)ethyl 2-(thiophen-3-yl)acetate (TDR1). Their physicochemical characterization by 1H NMR, FT-IR, DSC-TGA, GPC, UV-vis, cyclic voltammetry was carried out. These copolymers combine the high electron density and low oxidation potential of EDOT with the high charge mobility and processability of 3-HT. These are candidates for applications as active or barrier layer in electronic devices (bulk heterojuntion organic solar cells) or as functional membranes (e.g., sensors).