High-performance multi-junction cascade 1.3†µm quantum dot vertical cavity surface-emitting laser.

A high-performance 5-junction cascade quantum dot (QD) vertical cavity surface-emitting laser (VCSEL) with 1.3 µm wavelength was designed. The characteristics of the QD as active regions and tunnel junctions are combined to effectively increase output power. The photoelectric characteristics of single-junction, 3-junction cascade, and 5-junction cascade QD VCSELs are compared at continuous-wave conditions. Results indicate that the threshold current gradually decreases, and the output power and slope efficiency exponential increase with the increase of the number of active regions. The peak power conversion efficiency of 58.4% is achieved for the 5-junction cascade individual QD VCSEL emitter with 10 µm oxide aperture. The maximum slope efficiency of the device is 6.27 W/A, which is approximately six times than that of the single-junction QD VCSEL. The output power of the 5-junction cascade QD VCSEL reaches 188.13 mW at injection current 30 mA. High-performance multi-junction cascade 1.3-µm QD VCSEL provides data and theoretical support for the preparation of epitaxial materials.

Effect of Ga1-xInxAs1-yPy Al-free asymmetric barrier on GaAs-based 808-nm laser diode.

A GaInAsP/GaAs/GaAsP Al-free laser with asymmetric potential barriers is designed theoretically to prevent carrier leakage. The band alignment demonstrates that a high height of the potential barrier decreases the leakage current. The internal quantum efficiency increases by increasing the injection efficiency, which is attributed to the decreasing electron potential barrier heights. Moreover, the threshold current and operating voltage decrease by adopting a novel barrier so that the output power and power conversion efficiency (PCE) increase. When the injection current is 5 kA/cm2, the PCE is 77.82% and the output power is 13.21 W. The physical mechanism of potential barrier heights affecting carrier transport is investigated, which will provide a theoretical basis for optimizing laser diodes.

Effect of the combination of astragaloside IV and Panax notoginseng saponins on pyroptosis and necroptosis in rat models of cerebral ischemia-reperfusion.

Pyroptosis and necroptosis are closely associated with the mechanism underlying cerebral ischemia-reperfusion (I/R) injury. The combination of astragaloside IV (AST IV) and Panax notoginseng saponins (PNS) has remarkable effects on the alleviation of cerebral I/R damage. However, whether inhibition of pyroptosis and necroptosis is the mechanism underlying the beneficial effects of this drug combination on cerebral I/R injury remains unclear. To explore the effects and mechanisms of drug treatment, middle cerebral artery occlusion was performed to induce I/R injury in rats, which was verified based on neurological deficit score (NDS), infarct volume and H&E staining. Activation of pyroptosis and necroptosis was detected by western blot analysis of associated proteins. The results of the present study demonstrated that treatment with AST IV and PNS, either alone or in combination, significantly reduced the NDS, cerebral infarct volume and cell injury rate in the cerebral cortex of rats. The treatments also improved pathological injury to the cerebral cortex and reduced the levels of proteins associated with pyroptosis and necroptosis. These effects were stronger in the combination drug group compared with groups treated with a single drug alone. The findings of the present study suggested that the combination of AST IV and PNS exhibited stronger neuroprotective effects in I/R injury than either drug alone, and that the underlying mechanism was associated with inhibition of pyroptosis and necroptosis.

MEMS-Based Electrochemical Seismometer with a Sensing Unit Integrating Four Electrodes.

This paper presents a new process to fabricate a sensing unit of electrochemical seismometers using only one silicon-glass-silicon bonded wafer. By integrating four electrodes on one silicon-glass-silicon bonded wafer, the consistency of the developed sensing unit was greatly improved, benefiting from the high alignment accuracy. Parameter designs and simulations were carried out based on this sensing unit, which indicated that the sensitivities of the developed electrochemical seismometer decreased with the decrease in the number of flow holes in the sensing unit, and the initial stabilization time decreased gradually with the decrease in the thickness of the glass layer. Based on experimental results of four devices, the peak sensitivity was quantified as 5345.45 ± 43.78 V/(m/s) at 2 Hz, which proved high consistency of the fabricated electrochemical seismometer. In terms of the responses to random ground motions, high consistencies between the developed electrochemical seismometer and the commercial counterpart of CME6011 (R-sensors, Moscow, Russia) were found, where the developed electrochemical seismometer produced comparable noise levels to those of CME6011. These results validated the performance of the device and it may function as an effective tool for a variety of applications.

Temperature Compensation of the MEMS-Based Electrochemical Seismic Sensors.

Electrochemical seismic sensors that employ liquid as their inertial masses have the advantages of high performances in the low-frequency domain and a large working inclination. However, the surrounding temperature changes have serious impacts on the sensitivities of the sensors, which makes them unable to work as expected. This paper studied the temperature characteristics of electrochemical seismic sensors based on MEMS (micro-electro-mechanical systems), and analyzed the influences of the temperature effects on the open-loop and closed-loop amplitude-frequency curves. Most importantly, the temperature compensation circuits based on thermistors were developed, which effectively adjusted pole frequencies and sensitivity coefficients, and finally realized the real-time temperature compensation for both open-loop and closed-loop measurements for the first time. The results showed that in the temperature range of -10 °C ~ +40 °C, and with the 3 dB bandwidth range of 0.01 Hz ~ 40 Hz, the change of the maximum sensitivity was reduced from about 25 dB before temperature compensation to less than 2 dB after temperature compensation.

MEMS-Based Electrochemical Seismometer Relying on a CAC Integrated Three-Electrode Structure.

This study developed a MEMS-based electrochemical seismometer relying on a cathode-anode-cathode (CAC) integrated three-electrode structure where two cathodes were positioned on two surfaces of a silicon wafer, while one anode was positioned on the sidewalls of the through holes of the silicon wafer. Device design and numerical simulations were conducted to model the functionality of the three-electrode structure in detecting vibration signals with the key geometrical parameters optimized. The CAC integrated three-electrode structure was then manufactured by microfabrication, which demonstrated a simplified fabrication process in comparison with conventional four-electrode structures. Device characterization shows that the sensitivity of the CAC microseismometer was an order of magnitude higher than that of the CME6011 (a commercially available four-electrode electrochemical seismometer), while the noise level was comparable. Furthermore, in response to random vibrations, a high correlation coefficient between the CAC and the CME6011 (0.985) was located, validating the performance of the developed seismometer. Thus, the developed electrochemical microseismometer based on an integrated three-electrode structure may provide a new perspective in seismic observations and resource explorations.

Cross Talk Between Ferroptosis and Cerebral Ischemia.

Recently, ferroptosis has been revealed as a new form of regulated cell death. Distinct from apoptosis and necrosis, ferroptosis is evoked by iron-dependent lipid peroxidation. Furthermore, the metabolism of iron, lipids, and amino acids plays a significant regulatory role in ferroptosis, which can be reversed by glutathione peroxidase 4 and ferroptosis suppressor protein 1. Ferroptosis is implicated in the onset and development of numerous neurological diseases. Emerging studies have reported that ferroptosis induces and aggravates brain tissue damage following cerebral ischemia, whereas inhibition of ferroptosis dramatically attenuates induced damage. In this review, we have summarized the mechanistic relationship between ferroptosis and cerebral ischemia, including through iron overload, downregulation of glutathione peroxidase 4, and upregulation of lipid peroxidation. Although considerable attention has been paid to the effect of ferroptosis on cerebral ischemic injury, specific mechanisms need to be experimentally confirmed, including how cerebral ischemia induces ferroptosis and how ferroptosis deteriorates cerebral ischemia.

A newly characterized exopolysaccharide from Sanghuangporus sanghuang.

Sanghuangporus sanghuang is a well-known pharmacodynamic and economically important edible fungus associated with mulberry (Morus spp.). A distinctly new exopolysaccharide (EPS), designated SHP-2 was obtained from S. sanghuang P0988 broth, and its structure and anti-aging prosperity were characterized. SHP-2 was found to be composed of a back-bone of →4)-ß-Manp-(1→4)-α-Araf-(1→3,4)-α-Glcp(1→3,4)-α-Glcp-(1→3,4)-α-Glcp-(1→3,4)-α-Glcp-(1→3,4)-α-Glcp-(1→6)-α-Galp-(1→4)-ß-Manp-(1→ and five branches, including four α-D-Glcp-(1→ and one α-D-Manp-(1→SHP-2 was shown to increase antioxidant enzyme activities including catalase (CAT) and superoxide dismutase (SOD) activities, as well as trolox equivalent antioxidant (TEAC) capacity in serum of mice pre-treated with D-Gal, while reducing lipofuscin levels. SHP-2 exerted a favorable influence on immune organ coefficients and ameliorated the histopathological hepatic lesions and apoptosis in hepatocytes of D-galactose-aged mice almost in a dose-dependent manner. Using the same analytical methods, on comparison with previously studied EPS compounds (i.e. SHP-1), SHP-2 was found to have more complex structure, larger molecule weight, and different anti-aging properties. The results presented here suggest that not only does EPS bioactivity vary with respect to molecular structures and molecule weight, but that multiple structures with different activity can be expressed by a single fungal strain. These results may help understanding the anti-aging prosperity of these polysaccharides for use in health foods or dietary supplements.

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A field experiment was conducted to examine the effects of plastic film mulching (PM), straw retention (SR) and planting green manure (GM) on grain yield and nutrient concentrations of winter wheat. Compared to the traditional pattern (TP), plastic film mulching showed no significant effect on the average yield over the three years but increased the average phosphorus (P) uptake and concentration in grain by 8.4% and 13.0%, respectively. The average uptake of nitrogen (N), sulfur (S) and iron (Fe) was decreased by 12.6%, 15.0% and 11.1%, and the corresponding concentration was decreased by 12.1%, 12.9% and 10.1%, respectively. There was no significant effect on grain zinc (Zn) concentration. Straw retention decreased grain yield by 12.1%, reduced the average uptake of N, S and Fe decreased by 22.5%, 21.0% and 19.8%, and their corresponding concentration by 10.1%, 9.4% and 3.8%, respectively. The average uptake of P in grain was decreased by 9.8% with straw retention, while the P concentration was increased by 5.0%. There was no significant effect of straw retention on Zn concentration in grain. Planting green manure decreased the grain yield by 12.1%. It had no significant effect on the average uptake of N and Zn, but increased the grain N and Zn concentration by 12.1% and 12.6%, respectively. It showed no impact on P, S and Fe concentration in grain. The discordance between variation of grain yield and its nutrient uptake under different cultivations was the key reason for the changes of their nutrient concentration. Considering the potential adverse effects of plastic film mulching and straw retention on the quantity and quality of grain yield, suitable N fertilization should be applied to ensure the nutrient requirement for grain yield and regulate the uptake and utilization of N, S and Fe for improving the grain quality. Planting green manure could improve soil fertility and increase grain N and Zn concentration, but the yield reduction deserves more attention.