The profile of brain structural abnormalities in schizophrenia is still not fully understood, despite decades of research using brain scans. To validate a prospective meta-analysis approach to ...analyzing multicenter neuroimaging data, we analyzed brain MRI scans from 2028 schizophrenia patients and 2540 healthy controls, assessed with standardized methods at 15 centers worldwide. We identified subcortical brain volumes that differentiated patients from controls, and ranked them according to their effect sizes. Compared with healthy controls, patients with schizophrenia had smaller hippocampus (Cohen's d=-0.46), amygdala (d=-0.31), thalamus (d=-0.31), accumbens (d=-0.25) and intracranial volumes (d=-0.12), as well as larger pallidum (d=0.21) and lateral ventricle volumes (d=0.37). Putamen and pallidum volume augmentations were positively associated with duration of illness and hippocampal deficits scaled with the proportion of unmedicated patients. Worldwide cooperative analyses of brain imaging data support a profile of subcortical abnormalities in schizophrenia, which is consistent with that based on traditional meta-analytic approaches. This first ENIGMA Schizophrenia Working Group study validates that collaborative data analyses can readily be used across brain phenotypes and disorders and encourages analysis and data sharing efforts to further our understanding of severe mental illness.
Macroscopic mechanical objects and electromagnetic degrees of freedom can couple to each other through radiation pressure. Optomechanical systems in which this coupling is sufficiently strong are ...predicted to show quantum effects and are a topic of considerable interest. Devices in this regime would offer new types of control over the quantum state of both light and matter, and would provide a new arena in which to explore the boundary between quantum and classical physics. Experiments so far have achieved sufficient optomechanical coupling to laser-cool mechanical devices, but have not yet reached the quantum regime. The outstanding technical challenge in this field is integrating sensitive micromechanical elements (which must be small, light and flexible) into high-finesse cavities (which are typically rigid and massive) without compromising the mechanical or optical properties of either. A second, and more fundamental, challenge is to read out the mechanical element's energy eigenstate. Displacement measurements (no matter how sensitive) cannot determine an oscillator's energy eigenstate, and measurements coupling to quantities other than displacement have been difficult to realize in practice. Here we present an optomechanical system that has the potential to resolve both of these challenges. We demonstrate a cavity which is detuned by the motion of a 50-nm-thick dielectric membrane placed between two macroscopic, rigid, high-finesse mirrors. This approach segregates optical and mechanical functionality to physically distinct structures and avoids compromising either. It also allows for direct measurement of the square of the membrane's displacement, and thus in principle the membrane's energy eigenstate. We estimate that it should be practical to use this scheme to observe quantum jumps of a mechanical system, an important goal in the field of quantum measurement.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Optical emission spectroscopy, fast video imaging and coating characterization are employed to investigate AC plasma electrolytic oxidation (PEO) of magnesium alloys. The findings revealed initiation ...and gradual increase in the number of discharges after 2–4 ms of each anodic pulse once a critical voltage was reached. No discharges were observed during the cathodic half-cycles. The lifetimes of discharges were in the range of 0.05–4 ms. A transition in the voltage-time response, accompanied by a change in the acoustic and optical emission characteristics of discharges, was associated with the development of an intermediate coating layer with an average hardness of 270–450 HV
0.05. The coatings grew at a rate in the range 4.0–7.5 µm min
−
1
, depending on the substrate composition. Regardless of the substrate, the coatings consisted of MgO and Mg
2SiO
4, with incorporation of alloying element species. Electrolyte species were mainly present in a more porous layer at the coating surface, constituting 20–40% of the coating thickness. A thin barrier layer consisting of polycrystalline MgO was located next to the alloy. The corrosion rate of the magnesium alloys determined using potentiodynamic polarization in 3.5 wt.% NaCl was reduced by 2–4 orders of magnitude by the PEO treatment.
Heat stress during the dry period affects the cow’s mammary gland development, metabolism, and immunity during the transition period. However, the effect of late-gestation heat stress on calf ...performance and immune status is unknown. Our objective was to evaluate the effect of heat stress during the final ∼45d of gestation on growth and immune function of calves. Calves (17/treatment) were born to cows that were exposed to cooling (CL) or heat stress (HT) during the dry period. Only heifer calves (CL, n=12; HT, n=9) were used in measurements of growth and immune status after birth. Heifer calves were managed under identical conditions. All were fed 3.78L of colostrum from their respective dams within 4h of birth and were weaned at 2mo of age (MOA). Body weight (BW) was obtained at weaning and then monthly until 7 MOA. Withers height (WH) was measured monthly from 3 to 7 MOA. Hematocrit and plasma total protein were assessed at birth, 1, 4, 7, 11, 14, 18, 21, 25, and 28d of age. Total serum IgG was evaluated at 1, 4, 7, 11, 14, 18, 21, 25, and 28d of age, and apparent efficiency of absorption was calculated. Peripheral blood mononuclear cells were isolated at 7, 28, 42, and 56d of age, and proliferation rate was measured by 3H-thymidine incorporation in vitro. Blood cortisol concentration was measured in the dams during the dry period and in calves in the preweaning period. Gestation length was 4d shorter for HT cows compared with CL cows. Calves from CL cows had greater BW than calves from HT cows at birth (42.5 vs. 36.5kg). Compared with CL heifers, HT heifers had decreased weaning BW (78.5 vs. 65.9kg) but similar BW (154.6 vs. 146.4kg) and WH (104.8 vs. 103.4cm) from 3 to 7 MOA. Compared with CL, heifers from HT cows had less total plasma protein (6.3 vs. 5.9g/dL), total serum IgG (1,577.3 vs. 1,057.8mg/dL), and apparent efficiency of absorption (33.6 vs. 19.2%), and tended to have decreased hematocrit (33 vs. 30%). Additionally, CL heifers had greater peripheral blood mononuclear cell proliferation relative to HT heifers (23.8 vs. 14.1 fold). Compared with CL, late-gestation HT did not affect the blood cortisol concentration of dams during the dry period or that of the calves in the preweaning period, but CL calves tended to have increased circulating cortisol at birth (7.6 vs. 5.7µg/dL). We conclude that heat stress of the dam during the dry period compromises the fetal growth and immune function of offspring from birth through weaning.
Al-Ti-B is the most widely used grain refiner for many Al alloys. However, the precise mechanism of grain refinement is still not clear after 60years of intensive research. This work aims to further ...our understanding on the grain refining mechanism involving Al-Ti-B-based grain refiners. Extensive high-resolution electron microscopy investigation has confirmed the existence of a Ti-rich monolayer on the (0001) TiB2 surface, which is most likely to be a (112) Al3Ti two-dimensional compound (2DC). Further experimental investigation was carried out to understand the potency of TiB2 particles and the stability of the Al3Ti 2DC. Our results showed that the potency of TiB2 particles is significantly increased by the formation of a monolayer of Al3Ti 2DC on their surface. The Al3Ti 2DC forms at the liquid-Al/TiB2 interface in concentrated Al-Ti solutions, but dissolves in dilute Al-Ti solutions, although the kinetics of both the formation and dissolution of Al3Ti 2DC are relatively sluggish. Effective grain refinement by the Al-5Ti-1B grain refiner is directly attributed to the enhanced potency of TiB2 particles with the Al3Ti 2DC and sufficient free Ti solute in the melt after grain refiner addition to achieve the columnar-to-equiaxed transition.
► SKPFM provided information about galvanic interactions existing in Mg alloys. ► Galvanic interactions depended on the Volta potential differences of the alloy constituents. ► The Volta potential ...differences of the constituents depended on their composition. ► The as-cast ZE41 alloy presented strong galvanic corrosion. ► No evidence of galvanic corrosion by RE-containing phases was observed in WEXX alloys.
Four commercially produced rare-earth-magnesium alloys, as-cast ZE41, sand-cast WE43-T6, and wrought WE43-T6 and WE54-T6, were studied by scanning Kelvin probe force microscopy (SKPFM) in order to evaluate the role of their micro-constituent phases on potential galvanic interactions. Such interactions were then examined by immersion of the alloys in 3.5
wt% NaCl solution. The results confirmed that SKPFM was a powerful tool to determine the corrosion mechanism of magnesium alloys, where the intensity of the corrosion attack depended on the relative Volta potential differences of the micro-constituents, as well as their amounts, compositions and distributions within the alloys.
The corrosion performance of WE43-T6 and AZ91D magnesium alloys with and without treatment by plasma electrolytic oxidation (PEO) was investigated by electrochemical measurements in 3.5
wt.% NaCl ...solution. For untreated WE43-T6 alloy, formation of a uniform corrosion layer (Mg(OH)
2) was accompanied by initial pits around magnesium-rare earth intermetallic compounds. The AZ91D alloy disclosed increased corrosion susceptibility, with localized corrosion around the β-phase, though the β-phase network phase acted as a barrier for corrosion progression. PEO treatment in alkaline phosphate electrolyte improved the corrosion resistance of WE43-T6 alloy only at the initial stages of immersion in the test solution. However, PEO-treated AZ91D alloy revealed a relatively high corrosion resistance for much increased immersion times, contrary to the relative corrosion resistances of the untreated alloys. The improved performance of the PEO-treated AZ91D alloy appears to be related to the formation of a more compact coating.
Ni–B coatings have been deposited directly on commercial purity magnesium and AZ91D alloy and characterized using glow discharge optical emission spectroscopy, scanning electron microscopy, X-ray ...diffraction and, for tribological and mechanical evaluation, dry sliding wear and friction testing and microhardness measurement. The boron content of the coating on Mg was slightly lower than that of the coating on the AZ91D alloy. The wear rates were similar for both coatings and two magnitude orders lower than those of the substrates. The coefficients of friction were similar for both coatings, in the range ∼0.31 to 0.34. The values were close to that of the uncoated magnesium, while that for the AZ91D alloy was slightly lower, namely ∼0.25. The wear mechanism of the electroless Ni–B coatings was governed by the presence of abrasive wear, delamination and tribo-corrosion processes.
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•Tribological properties of electroless Ni–B coatings on Mg substrates are determined.•Boron content and hardness differ between Mg and AZ91D alloy substrates.•Ni–B significantly reduces wear rates, with little effect on coefficients of friction.•Wear mechanisms of the coatings are assessed by scanning electron microscopy.
The formation of alumina-based coatings on aluminium by AC plasma electrolytic oxidation (PEO) has been investigated using a silicate electrolyte with selective additions of fine zirconia particles. ...The coatings comprised an amorphous barrier layer, a relatively dense intermediate layer and a more porous outer layer that contained silicon species. Zirconia was incorporated non-uniformly into the outer layer and, to a limited extent, the intermediate layer, as both particles and a component of cellular microstructures. Following treatments firstly in zirconia-containing electrolyte and secondly in zirconia-free electrolyte, the zirconia did not extend beyond about the middle of the intermediate layer, indicating its limited inward mass transfer during microdischarges. The coating efficiency decreased at oxidation times in excess of 40
min due to dissolution of either the substrate or the coating, or physical loss of coating material. The oxidation of aluminium consumed on average ∼29% of the anodic charge; the remainder was used mainly in generation of oxygen gas.
The mechanism of growth of anodic titanium oxide in sulphuric acid has been investigated by potentiostatic and potentiodynamic anodizing, electrochemical impedance spectroscopy and transmission ...electron microscopy. It was found that most of the charge passed during growth is consumed in oxygen evolution at the oxide–solution interface and the measured current relates to the electronic conduction properties of the oxide. Further, it was confirmed that an amorphous to crystalline transition takes place during potentiodynamic growth, and the transition triggers the additional generation of oxygen bubbles that occurs within the oxide. Depending on the growth conditions, the oxygen bubbles can rupture with local re-growth of the film then occurring.
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