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In this work, near-infrared Au-grating/MoS2/Au hot-electron photodetectors (HEPDs) with magnetic polaritons (MPs) beneath the top Au grating strips are designed and proposed. The MPs are formed by the near-field coupling between the grating and the bottom Au film, which achieves a light absorption greater than 99.5% at 1550 nm for the HEPDs. The simulations show that the absorption wavelength can be tuned independently and widely to cover the whole short wavelength infrared band by adjusting width of the grating strips, and the near-perfect absorption characteristics can be maintained. Then, dual-frequency HEPDs with two different grating strip widths in one cycle of the Au-grating are designed. Without external bias, the theoretical responsivities as high as 11.2 mA W−1 at 1200 nm and 6.2 mA W−1 at 1550 nm are achieved for the HEPDs by a three-step electrical model. In addition, a modulation distance between the two absorption peak positions of the HEPDs could be larger than 1100 nm. This provides a new idea for the realization of high-responsivity near-infrared HEPDs for arbitrary dual-band detection, which has great potential in modern optical communication systems.

AIM This study aimed to evaluate the effectiveness of probiotics in treating children with acute diarrhoea and dehydration. METHODS Medline, EMBASE, and the Cochrane Library databases were searched for relevant studies and statistical analysis was performed. RESULTS A total of 17 randomised controlled trials (RCTs) involving 2861 participants met the inclusion criteria. Compared with placebo, probiotics reduced the duration of diarrhoea (12 RCTs [15, 17], n = 1907, mean difference - 21.33 h, confidence interval (CI) -29.74 to -12.91, high heterogeneity, I2 = 86%), the duration of hospitalisation when compared with placebo (eight RCTs [19, 20], n = 1606, mean difference - 0.83 days, CI -1.53 to -0.12, high heterogeneity, I2 = 96%) and reduced risk of diarrhoea on day 4 or more days (six RCTs [19, 20], n = 1093, risk difference - 0.13, 95% CI -0.17- -0.09, no heterogeneity). CONCLUSIONS Probiotics alongside rehydration therapy appear to be safe and have clear beneficial effects in shortening the duration of diarrhoea in children with acute diarrhoea and dehydration.

Binary metal layers composed of a grating and a thin film are designed for high-responsivity metal–insulator–metal (MIM) near-infrared hot-electron photodetectors (HEPDs). The binary metal grating structure HEPDs demonstrate a strong asymmetrical optical absorption and result in a high current responsivity. In our devices, the top and bottom absorption ratio is as high as 76:1, much higher than that in the traditional grating structure HEPDs. The maximum zero-biased responsivity is 0.585 mA/W at 1550 nm by employing a five-step electrical model, which is 3.42 times that of the traditional silver grating structure devices. Simply changing the grating period enables spectrally selective photodetection covering a wide range of 500 nm at the near-infrared band with net absorption higher than 0.95 and linewidths narrower than 0.7 meV.

Aliphatic poly(monothiocarbonate)s synthesized by alternating copolymerization of carbonyl sulfide (COS) and epoxides are a new type of crystalline polymers. In this work, the isothermal crystallization behavior and spherulite morphology of poly(trimethylene monothiocarbonate) (PTMMTC) and poly(ethylene monothiocarbonate) (PEMTC) are studied. PTMMTC tends to form banded spherulites, especially at low crystallization temperatures, while PEMTC forms non-banded spherulites. The overall crystallization rate and spherulitic growth rate of PTMMTC are larger than those of PEMTC at the same degree of supercooling. PTMMTC with longer alkane segment in the main chain has a higher equilibrium melting temperature (Tm0) than PEMTC. Both polymers exhibit double melting peaks, but the formation mechanisms are different for PTMMTC and PEMTC. Small-angle X-ray scattering (SAXS) result reveals that more amorphous phases are located in interlamellae of PTMMTC, leading to a larger long period (L) and a thicker amorphous layers (la), which can account for the stronger tendency of PTMMTC to form banded spherulites. The melting enthalpies of PTMMTC and PETMC crystals with 100% crystallinity (ΔHm0) are obtained by extrapolating the melting enthalpies of the samples with different crystallinities. The free energy of the folding surface (σe) of PTMMTC is larger than that of PETMC, indicating that the PTMMTC chain is stiffer. The higher Tm0 and larger ΔHm0 and σe of PTMMTC can be attributed to its stronger interchain interaction.

Ring-opening polymerization (ROP) of the bioderived and nonstrained γ-butyrolactone (γ-BL) is an emerging approach to produce recyclable polymers. It remains a big challenge to synthesize high molecular weight linear poly(γ-butyrolactone)s (PγBLs) in a highly active and selective manner. In this report, we developed dual organocatalysts for the ROP of γ-BL, using symmetrical (thio)ureas with electron-donating groups to buffer the growing anions that were generared by the superbase phosphazene (P4). Linear PγBLs were selectively obtained with high apparent rate constant (ca. 39 times than single P4), and high number-average molecular weights of up to 64.3 kg/mol (ca. 3 times than single P4). The turnover frequencies of these P4/(thio)urea pair-catalyzed processes were as high as 125 h–1. High molecular weight PγBLs exhibited dramatically improved mechanical properties.

The effect of high-speed direct-chill (DC) casting on the microstructure and mechanical properties of Al–Mg2Si in situ composites and AA6061 alloy was investigated. The microstructural evolution of the Al–Mg2Si composites and AA6061 alloy was examined by optical microscopy, field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The results revealed that an increase of the casting speed substantially refined the primary Mg2Si particles (from 28 to 12 μm), the spacing of eutectic Mg2Si (from 3 to 0.5 μm), and the grains of AA6061 alloy (from 102 to 22 μm). The morphology of the eutectic Mg2Si transformed from lamellar to rod-like and fibrous with increasing casting speed. The tensile tests showed that the yield strength, tensile strength, and elongation improved at higher casting speeds because of refinement of the Mg2Si phase and the grains in the Al–Mg2Si composites and the AA6061 alloy. High-speed DC casting is demonstrated to be an effective method to improve the mechanical properties of Al–Mg2Si composites and AA6061 alloy billets.

The pseudoscalar meson-baryon octet interaction is studied within a nonlinear realized Lagrangian, and then the Bethe-Salpeter equation is solved in the unitary coupled-channel approximation. In sector of strangeness $S=-1$ and isospin $I=0$, only one pole is generated dynamically in the 1400MeV region, which might correspond to the $\Lambda(1405)$ particle. When the case of strangeness zero is studied, the $s-$ and $u-$ potentials are taken into account in the kernel, and a resonance state is produced in the 1500MeV region, which might be a counterpart of the N(1535) particle., Comment: 5 pages. Talk given at the XVIII International Conference on Hadron Spectroscopy and Structure(HADRON2019), August 16-21, Guilin, China

In high-income countries. ondansetron is an effective antiemetic in children with gastroenteritis, but data from low- and middle-income countries are sparse. This study aimed to evaluate evidences of the effectiveness of ondansetron in preventing vomiting and reducing the use of intravenous fluids in children with gastroenteritis in developing countries. A total of nine randomized controlled trials (RCTs) involving 2313 participants met the inclusion criteria. Compared with placebo, ondansetron reduced the use of intravenous rehydration (three RCTs, n = 1126, relative risk (RR) 0.60, 95% confidence interval (CI) 0.38-0.95, no significant heterogeneity, I2 = 43%), the risk of failure of oral rehydration therapy among children with gastroenteritis-associated vomiting and dehydration (four RCTs, n = 1370, RR 0.58, 95% CI 0.43-0.79; no significant heterogeneity was found, I2 = 39%) and risk of hospitalization (2 RCTs, n = 264, RR 0.25, 95% CI 0.09-0.73, no heterogeneity, I2 = 0).Conclusions: Compared with placebo, ondansetron reduced the use of intravenous fluids in children with gastroenteritis and dehydration. It has no effect on children with gastroenteritis who do not present with dehydration in developing countries. While ondansetron is effective in controlling vomiting and reducing the rate of hospitalization, there is no evidence that it is effective in reducing the rate of readmission. What is Known: • In high-income countries, ondansetron can reduce the use of intravenous fluids in children with gastroenteritis and dehydration. • No systematic review and meta-analysis of randomized controlled trials were done in a developing country setting. What is New: • In developing countries, ondansetron reduces the use of intravenous fluids in children with gastroenteritis and dehydration. • It has no effect on children with gastroenteritis but without dehydration.

In this paper, the morphology transition and the growth process of the primary Mg2Si in the Al–Mg2Si in situ composites were three-dimensionally investigated by observing the extracted Mg2Si particles. The primary Mg2Si transforms from perfect octahedron to truncated octahedron with increasing cooling rate. Combining with the crystal morphologies obtained at different growth stages, the growth mechanism of octahedral Mg2Si was discussed. In the early growth stage of the octahedral Mg2Si, the secondary branches preferentially grow on the advancing tips of the first branches. Then, the hollows in the {111} faces shrink gradually and the octahedral Mg2Si forms finally. With the increase of Mg2Si content, dendritic Mg2Si phases were observed and the truncated octahedron Mg2Si connect mutually to form the complicated morphology at low cooling rate. The high cooling rate transforms the morphology of the Mg2Si crystal. The growth rates of the 〈100〉 and 〈111〉 axes can be manipulated by adjusting the cooling rates, which are responsible for the evolution of the Mg2Si crystals.

Polyester synthesis from the alternating copolymerization of epoxides with cyclic anhydrides via a metal-free route remains a key challenge. This work reports the development of a highly active organocatalytic route for the copolymerization of a spectrum of epoxides and cyclic anhydrides. Fully alternating polyesters were synthesized by a variety of organic Lewis acid–base pairs including organoboranes and quaternary onium salts. The effect of the acidity, type, and size of Lewis pairs on the catalytic activity and selectivity of the copolymerization is presented. The undesirable transesterification and etherification were effectively suppressed even in the case of complete conversion of the cyclic anhydride. This could be ascribed to the formation of a unique tetracoordinate bond-carboxylate (or alkoxide) anion. The Lewis pairs are highly active, with a turnover frequency of 102 and 303 h–1 for the copolymerization of propylene oxide with maleic anhydride and phthalic anhydride, respectively, at 80 °C. B...

For the composite structure comprised of steel-lined concrete, the inside steel liner and surrounding reinforced concrete are designed to work reliably. The potential sliding between the reinforced concrete and steel liner has a significant effect on the structure bearing mechanism. The Coulomb friction model is employed to simulate the sliding of the steel liner against the surrounding concrete. A concrete damage plasticity (CDP) model is proposed to simulate the surrounding reinforced concrete. The finite element (FE) models of the steel-lined reinforced concrete penstock (SLRCP) located on the downstream surface of a double curvature arch concrete dam are developed, in which the nodes-shared method (NSM) and the friction-contact method (FCM), respectively, are employed. The concrete crack initiation time, concrete crack propagation pattern, penstock deformation, tensile stresses of the steel liner and the reinforcements are presented. The results of the FCM model agree well with the monitoring data, validating that the proposed model could be directly employed in the FE software ABAQUS.

A semicrystalline poly(trimethylene monothiocarbonate) (PTMMTC) has been synthesized via the selective and alternating copolymerization of carbonyl sulfide and oxetane. This reaction was catalyzed by (salen)CrCl accompanied by organic bases over a wide range of temperatures from 40 to 130 °C. PTMMTC is shown to exhibit similar crystallization behavior to high-density polyethylene (HDPE), i.e., being spherulite and possessing melting temperatures (Tm) up to 127.5 °C and a degree of crystallinity (Xc) of up to 71%. Moreover, PTMMTC has a wide processing temperature window of ca. 100 °C.

A one-pot synthesis of block copolymer with regioregular poly(monothiocarbonate) block is described via metal-free catalysis. Lewis bases such as guanidine, quaternary onium salts, and Lewis acid triethyl borane (TEB) were equivalently combined and used as the catalysts. By using polyethylene glycol (PEG) as the macromolecular chain transfer agent (CTA), narrow polydispersity block copolymers were obtained from the copolymerization of carbonyl sulfide (COS) and propylene oxide (PO). The block copolymers had a poly(monothiocarbonate) block with perfect alternating degree and regioregularity. Unexpectedly, the addition of CTA to COS/PO copolymerization system could dramatically improve the turnover frequency (TOF) of PO (up to 240 h−1), higher than that of the copolymerization without CTA. In addition, the conversion of CTA could be up to 100% in most cases, as revealed by 1H NMR spectra. Of consequence, the number-average molecular weights (Mns) of the resultant block copolymers could be regulated by varying the feed ratio of CTA to PO. Oxygen-sulfur exchange reaction (O/S ER), which can generate randomly distributed thiocarbonate and carbonate units, was effectively suppressed in all of the cases in the presence of CTA, even at 80 °C. This work presents a versatile method for synthesizing sulfur-containing block copolymers through a metal-free route, providing an array of new block copolymers.

The preparation of perfectly alternating and regioslective copolymers derived from the copolymerization of carbonyl sulfide (COS) and epoxides by metal-free Lewis pair catalysts composed of a Lewis base (amidine, guanidine, or quaternary onium salts) and a Lewis acid (triethyl borane) is described. Colorless and highly transparent copolymers of poly(monothiocarbonate) were successfully obtained with over 99 % tail-to-head content and high molecular weight (up to 92.5 kg mol−1). In most instances, oxygen–sulfur exchange reactions (O/S ERs), which would generate random thiocarbonate and carbonate units, were effectively suppressed. The turnover frequencies (TOF) of these Lewis pair catalyzed processes were as high as 119 h−1 at ambient temperature.

Traditionally, spiral case structure is classified as non-member bar reinforced concrete structure. It is improper to calculate reinforcement area according to the area of tensile stress figure, which often causes a lot of waste of reinforcement; it is particularly true for the spiral case structure with steel liner. In combination with the practice of a spiral case of the hydropower station, the different schemes are proposed by 3-D nonlinear FEM software ABAQUS to study the feasibility of thinning steel liner in this paper. It is indicated that magnitude of steel liner and the hoop reinforcement stress is of no obviously increasement, damaged region of concrete is of no significant variation and the cracking range of peripheral concrete is of the requirements when the rate of steel liner thinning is tiny. When the thinning rate is 10%, there is a significant increase in crack width, but it still can meet the requirements of the specification. Although the magnitude of the stresses is not beyond the strength requirement, the maximum cracking width of concrete is over the designed standards when the rate is up to 30%. In this case, the crack width is controlled by collocating the more reinforcement in local positions. It is concluded that steel liner thinning is reasonable and feasible; what’s more, the magnitude of thinning is very large when the more reinforcement are collocated without prejudice to construction. It can provide references for optimization of the steel liner for the similar projects.

In combination with the practice of a large hydropower station, concrete damaged plasticity model is introduced into the steel-liner reinforced concrete penstock for the nonlinear analysis, the damage distribution rules of the surrounding concrete and the stresses of the steels are furtherly studied under the different tension softening characteristic curves, the conclusions can provide the reference for damage assessment of the surrounding concrete and the optimization allocation of the reinforcement for the penstock.

In combination with the practice of a hydropower station steel-liner reinforced concrete penstock, the finite element model is established to analyze bearing characteristics of the penstock. In the paper, cracking behaviors of the surrounding concrete as well as stresses of the steel liner and reinforcement under normal water pressure are intensively studied based on the model test. The results can provide the basis for the safety operation of the steel-liner reinforced concrete penstock.

In combination with the practice of a pumped storage hydropower station, a 3-D nonlinear finite element method on the preloading filling spiral case is carried out to compare and analyze stresses of the steel spiral case and hoop reinforcement, the stress and bearing ratio of the surrounding concrete, the contact state between the spiral case and concrete in different precast water head. The results indicate that the stress of the surrounding concrete will get better with the increasing of precast water head. But there is a distance between the spiral case and the surrounding concrete when the water head is excessive, which is unhelpful for operating of the unit. When the precast water head of the spiral case is 439m or so, it can play a greater degree of mechanical characteristics of steel and concrete under the premise of operating stably of the unit.

To study the serum homocysteine (Hcy) distribution and characteristics in different sex and age groups in the community residents in Wuhan, and to analyse its associated factors with multi-stepwise regression analysis.The population under study was from three community areas in Wuhan. Demographic distribution and the correlation with other risk factors of serum Hcy were analyzed statistically.(1) Geometric mean of serum Hcy was 14.43 micromol/L in males and 10.89 micromol/L in females with P0.001. (2) Hcy of per age level in males was also higher (P0.001). (3) The prevalence rate of hyperhomocysteinemia was 23.94% in the general population in Wuhan. The prevalence rate of hyperhomocysteinemia in males was 2.62 times higher than in females. (4) Multi-stepwise regression analysis showed that Hcy had different affecting factors in males and females. The affecting factors of Hcy in males were daily cigarettes smoking, urine micro-albumin (UMALB) and times of exercise per week. The affecting factors of Hcy in females were duration of exercise each time, weight, triglyceride (TG), high-density lipoprotein (HDL), urine micro-albumin (UMALB) and age.(1) Hcy at the population level was significantly different by sex and age. (2) Population living in the community in Wuhan had a higher serum level and prevalence rate of Hcy comparing to some other cities in China and even in developed countries. (3) The important affecting factors of Hcy in population also showed sex difference, unlike the reports from other countries or other areas in China. Serum Hcy seemed to be affected by environmental and other factors.