Effects of exercise on post-stroke cognitive function: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: A growing body of research examining the effect of exercise on cognitive function in stroke patients, while findings of available studies were conflicting. OBJECTIVES: We aimed to estimate the effect of exercise on cognitive function in stroke patients. METHODS: For this systematic review and meta-analysis, we searched PubMed, Web of Science, Embase, Cochrane, and Scopus electronic databases, through 13 March 2023. The three-level restricted maximum likelihood random effects model was used to synthesize the data. RESULTS: Twenty-five studies met the inclusion criteria. There was a significant effect of exercise on improving cognitive function in stroke patients (Cohen's d = 0.37, 95% CI, 0.16 to 0.58, p < 0.01, I2 = 22.12%). Subgroup analysis showed that exercise significantly improved memory. In addition, aerobic exercise, exercise conducted 12 weeks or more, 3 times or more per week, less than 60 minutes per session, less than 180 minutes per week, and up to 12 months post-stroke increased cognitive function significantly. CONCLUSIONS: Exercise improved cognitive function in stroke patients. To improve cognitive function, this meta-analysis provides clinicians with evidence to recommend that stroke patients participate in aerobic exercise at least 3 times per week for 30-60 minutes, with a goal of 180 minutes per week being achieved by increasing the frequency of exercise. Exercise initiated within 12 months post-stroke and continued for 12 weeks or more is most beneficial for improving cognitive function.

Climate-adaptive crop distribution can feed food demand, improve water scarcity, and reduce greenhouse gas emissions.

Optimizing crop distribution stands as a pivotal approach to climate change adaption, enhancing crop production sustainability, and has been recognized for its immense potential in ensuring food security while minimizing environmental impacts. Here, we developed a climate-adaptive framework to optimize the distribution of staple crops (i.e., wheat, maize, and rice), hoping to meet the multi-dimensional needs of crop production in China. The framework considers the feasibility of the multiple cropping systems (harvesting more than once on a cropland a year) and adopts a multi-dimensional approach, incorporating goals related to crop production, water consumption, and greenhouse gas (GHG) emissions. By optimizing, the total irrigated area of three crops would decrease by 7.7 % accompanied by a substantial 69.8 % increase in rain-fed areas compared to the baseline in 2010. This optimized strategy resulted in a notable 10.0 % reduction in total GHG emissions and a 13.1 % decrease in irrigation water consumption while maintaining consistent crop production levels. In 2030, maintaining the existing crop distribution and relying solely on yield growth would lead to a significant maize production shortfall of 27.0 %, highlighting a looming challenge. To address this concern, strategic adjustments were made by reducing irrigated areas for wheat, rice, and maize by 2.3 %, 12.8 %, and 6.1 %, respectively, while simultaneously augmenting rain-fed areas for wheat and maize by 120.2 % and 55.9 %, respectively. These modifications ensure that production demands for all three crops are met, while yielding a 6.9 % reduction in GHG emissions and a 15.1 % reduction in irrigation water consumption. This optimization strategy offers a promising solution to alleviate severe water scarcity issues and secure a sustainable agricultural future, effectively adapting to evolving crop production demands in China.

TIR8 Protects Against Nonalcoholic Steatohepatitis by Antagonizing Lipotoxicity-induced PPARα Downregulation and Reducing the Sensitivity of Hepatocytes to LPS.

In up to one-third of nonalcoholic fatty liver disease (NAFLD) patients, simple steatosis progresses to its more severe form, nonalcoholic steatohepatitis (NASH), but the precise mechanisms underlying this transition are not fully understood. Toll/interleukin-1 receptor 8 (TIR8), a conventional innate immune regulator highly expressed in hepatic tissue, has shown potential for ameliorating various inflammation-related disorders. However, its role in NASH pathogenesis, especially its regulatory effects on lipid metabolism and inflammatory responses, is still unclear. Here, using a TIR8 knockout (TIR8KO) mouse model and mass spectrometry analyses, we found that TIR8KO mice displayed aggravated hepatic steatosis and inflammation, whereas TIR8 overexpression attenuated these adverse effects. Ectopic TIR8 expression counteracts free fatty acid (FFA)-induced PPARα inhibition and downstream signaling. A decrease in TIR8 levels in hepatocytes heightened lipopolysaccharide (LPS) sensitivity. Notably, FFA stimulation led to a direct interaction between TIR8 and proteasome subunit alpha type 4 (PSMA4), facilitating TIR8 degradation. These results revealed that TIR8 safeguards PPARα-regulated lipid metabolism and mitigates inflammation induced by external factors during NASH progression. Our study highlights TIR8 as a promising target for NASH therapy, indicating the potential of TIR8 agonists in treatment strategies.

Potential benefits of cropping pattern change in the climate-sensitive regions of rice production in China.

Rice production is a primary contributor to global greenhouse gas emissions, with unclear pathways towards carbon neutrality. Here, through a comprehensive assessment of direct greenhouse gas (GHG) emission using DNDC model and indirect GHG emission using emission factor methods, we estimated the annual crop yield, GHG emission amount and intensity, and economic benefits of different cropping patterns in the climate-sensitive regions of rice production in China. Through the expansion of single-rice and cropping pattern change from the wheat-rice to wheat-rice-rice in the climate-sensitive regions of single and triple-cropping cultivations, the total grain yield increased by 4.4 % and 4.5 % compared with the current national grain production, the GHG emission would increase by 2.4 % and 5.4 % of the current national GHG emissions from rice and wheat production, the net economic benefits could increase 0.9 % and decrease 2.0 % of the national output value of rice and wheat production. The study takes the entire-life cycle of crop growth as the principal line, and could provide a valuable reference for the regulation of the cropping pattern and the formulation of carbon reduction policies in the climate-sensitive region.

[Blood cadmium level and the change of cadmium exposure risk in Chinese urban school-age children in 2002 and 2012].

OBJECTIVE: To investigate the blood cadmium concentrations and the related change in Chinese urban children derived from the China Nutrition and Health Survey 2002 and 2012(CNHS 2002 and CNHS 2012). METHODS: The Chinese urban children aged 6-11 years were selected according to gender, age and regional distribution using the multi-stage stratified cluster random sampling method, as well as the corresponding whole blood samples. The blood cadmium concentration was carefully determined by the quadrupole inductively coupled plasma mass spectrometry(ICP-MS) and the percentage of blood cadmium over 2 µg/L was subsequently estimated. In addition, the upper limit values of the 95%CI of the 95th percentiles of available blood cadmium data was assessed as the threshold of cadmium exposure. RESULTS: Totally, 2182 Chinese urban children were included, and of these, 1036 children were from the CNHS 2002 and 1146 children were from the CNHS 2012. From the CNHS 2002 to the CNHS 2012, the median blood cadmium concentration was increased from 0.28 µg/L to 0.95 µg/L, and the percentage of blood cadmium with over 2 µg/L was elevated from 1.45% to 10.47%. In addition, the new estimated threshold of blood cadmium was ascended from 1.24 µg/L up to 2.89 µg/L. CONCLUSION: The risk of cadmium exposure in Chinese urban children aged 6-11 years was increasingly aggravated from the CHNS 2002 to the CNHS 2012.

Adaptation measures of the potential double cropping region in Northern China to future climate change.

In the context of climate change, the northern climate-based boundaries of the winter wheat-summer maize double cropping system (DCS) have moved northward and westward. The selection of spring maize single cropping system (SCS) or DCS in the potential DCS region in northern China directly affects the annual crop yield, resource use efficiency, and greenhouse gas (GHG) emissions. Reducing GHG emissions while improving yield and resource use efficiency is essential to green agricultural development. We used future climate data (2021-2060, SSP2-4.5 and SSP5-8.5), along with crop and soil data, to assess the applicability of the Denitrification-Decomposition Model (DNDC) for simulating crop yield and GHG emissions. Through simulation of DNDC, we identified a cropping system that prioritized high yield, resource use efficiency, and GHG emissions reduction, adapting to future climate change. Under this cropping system, we quantified the effects of various straw incorporation rates, irrigation, and nitrogen input on crop yield, resource use efficiency, and GHG emissions. We proposed optimal measures to adapt to future climate change while aiming for high yield, resource use efficiency, and GHG emissions reduction. The results show that the DNDC reliably simulated yield and GHG emissions for the (SCS) and the DCS. In counting for greenhouse gas emission intensity (GHGI) as GHG emissions normalized by crop yield, the GHGI was reduced by 86.4% and 89.2% in DCS than in SCS under the SSP2-4.5 and SSP5-8.5, respectively. In the study area, the DCS should be adopted for high yield, resource use efficiency, and GHG emissions reduction (increased by 28.4% and 34.4%) in the SSP2-4.5 and SSP5-8.5 with 1) straw incorporation rate for 100% of winter wheat and for 60% of summer maize; 2) total irrigating 240 mm for winter wheat at pre-sowing, jointing, booting, and filling stages; and 3) applying nitrogen of 168 kg·N/ha for both crops.

Estimation of 24-hour urinary sodium and potassium excretion among Chinese adults: a cross-sectional study from the China National Nutrition Survey.

BACKGROUND: High-sodium intake is one of the most important risk factors for hypertension and cardiovascular disease, yet reliable national estimates of sodium intake in Chinese adults have not been reported. OBJECTIVES: We estimated 24-h urinary sodium and potassium excretion and population daily sodium and potassium intake of Chinese adults for the first time at a national level. METHODS: A nationally representative cross-sectional survey was conducted to collect 24-h urine specimens from Chinese adults aged ≥18 y as part of the China National Nutrition Survey 2015. Finally, 10,114 participants (4932 males and 5182 females) with complete 24-h urine specimens were included in the analysis. Estimates of mean urinary electrolyte excretion and demographic, socioeconomic, and health characteristics were used with weighted coefficients that accounted for sample selection probabilities, poststratification weighting, and nonresponse rates. RESULTS: The estimation of overall weighted mean 24-h urinary sodium excretion was 4121 mg (95% confidence interval [CI]: 3993, 4250), 4155 mg (95% CI: 3993, 4317) in males and 4081 mg (95% CI: 3953, 4209) in females (P for sex difference = 0.36). Overall mean 24-h urinary potassium excretion was 1534 mg (95% CI: 1492, 1577), 1468 mg (95% CI: 1424, 1513) in males and 1614 mg (95% CI: 1569-1660) in females (P for sex difference <0.001). Mean 24-h urinary sodium excretion was significantly higher in rural adults (4350 mg; 95% CI: 4217, 4483) than in urban residents (3909 mg; 95% CI: 3739, 4080; P < 0.001), and in northern residents (4388 mg; 95% CI: 4237, 4539) than in southern residents (3998 mg; 95% CI: 3832, 4163; P = 0.002). CONCLUSIONS: The first nationwide survey with 24-h urine collection confirmed that mean sodium intake in Chinese adults was more than twice the upper limit, whereas mean potassium intake was <60% of the lower limit, recommended by the World Health Organization. Urgent measures should be taken to reduce sodium intake and increase potassium intake in China.

TSP50 Attenuates DSS-Induced Colitis by Regulating TGF-ß Signaling Mediated Maintenance of Intestinal Mucosal Barrier Integrity.

The integrity of the intestinal mucosal barrier is crucial for protecting the intestinal epithelium against invasion by commensal bacteria and pathogens, thereby combating colitis. The investigation revealed that the absence of TSP50 compromised the integrity of the intestinal mucosal barrier in murine subjects. This disruption facilitated direct contact between intestinal bacteria and the intestinal epithelium, thereby increasing susceptibility to colitis. Mechanistic analysis indicated that TSP50 deficiency in intestinal stem cells (ISCs) triggered aberrant activation of the TGF-ß signaling pathway and impeded the differentiation of goblet cells in mice, leading to impairment of mucosal permeability. By inhibiting the TGF-ß pathway, the functionality of the intestinal mucosal barrier is successfully restored and mitigated colitis in TSP50-deficient mice. In conclusion, TSP50 played a crucial role in maintaining the intestinal mucosal barrier function and exhibited the preventive effect against the development of colitis by regulating the TGF-ß signaling pathway.

Intrinsic relationship of outdoor activities between climate change and coastal management: Fresh evidence from the spatial analysis of China.

By utilizing the mediation effect model and the spatial Durbin model, this research investigates the influence that environmental restrictions have had on marine pollution in 38 coastal prefecture-level cities from the years 2000-2018. In order to gain a comprehensive understanding of the effect that environmental legislation has on contamination in offshore regions as well as its primary goal, the research takes a variety of different approaches into consideration. Following are the findings from the study; Firstly, pollution levels in coastal marine areas tend to rise at first and then fall when environmental laws are enacted, illustrating a non-linear pattern known as an inverted "U" shape. In order to improve the maritime environment through environmental legislation, it is crucial to support new green technologies. There is a "U" shaped linkage amongst environmental legislation and development of environmentally friendly technologies. Spatial spillover effects may allow for the regulation of coastal city environments to affect marine pollution in neighboring areas. Secondly, there is also an inverted "U" pattern visible in the impact trajectory of this effect. According to the results of this research, it is crucial to set up a strict and factually sound regulatory framework in the field of marine environmental governance. It is also suggested that local context be taken into account while crafting environmental regulating regulations. Also, it's crucial to promote development, dissemination, and use of green technology by completely capitalizing on the innovation's conduction effect. Thirdly, promoting cooperation efforts among areas to avoid and control such pollution is essential, and the transfer and management of offshore pollution between regions must be a top priority.

Setting sodium targets for pre-packaged foods in China - an exploratory study.

Introduction: Setting sodium targets for pre-packaged food has been a priority strategy for reducing population sodium intake. This study aims to explore the attitudes and considerations of researchers and key stakeholders toward implementing such policy in China. Methods: An exploratory study comprising a survey and a focus group discussion was conducted among 27 purposively selected participants including 12 researchers, 5 consumers, 4 administrators, 3 industry association representatives and 3 food producers. The survey/discussion covered the key questions considered when developing/promoting sodium targets. Free-text responses were manually classified and summarized using thematic analysis. Results: Two-thirds of the participants supported target-setting policy. Researchers and administrators were most supportive, and food producers and associations were least supportive. Adapted WHO food categorization framework was well accepted to underpin target-setting to ensure international comparability and applicability for Chinese products. Maximum values were the most agreed target type. The WHO benchmarks were thought to be too ambitious to be feasible given the current food supply in China but can be regarded as long-term goals. Initially, a reduction of sodium content by 20% was mostly accepted to guide the development of maximum targets. Other recommendations included implementing a comprehensive strategy, strengthening research, engaging social resources, establishing a systematic monitoring/incentive system, maintaining a fair competitive environment, and developing a supportive information system. Target-setting policy was acceptable by most stakeholders and should be implemented alongside strategies to reduce discretionary salt use. Discussion: Our findings provide detailed guidance for the Chinese government when developing a target-setting strategy. The methods and results of this study also provide meaningful references for other countries to set sodium targets for pre-packaged foods and implement other salt reduction strategies simultaneously.

Predictive Equation for Basal Metabolic Rate in Normal-Weight Chinese Adults.

This study aimed to develop a predictive equation for basal metabolic rate (BMR) in normal-weight Chinese adults and provide a reference for establishing the national recommended dietary energy intake. A new equation for BMR was derived from a sample of 516 normal-weight Chinese adults (men = 253, women = 263), and this sample was collected from two previous studies. Furthermore, the accuracy of this new equation and eight other previous predictive equations was reviewed. The agreement and reliability were compared in terms of bias, accuracy, the intraclass correlation coefficient, and Bland-Altman plots between predictive equations. In addition, the newly developed equation was further verified using a small independent sample, which contained 41 healthy Chinese adults (men = 21, women = 20). The measured BMR (mBMR) of all participants, measured using indirect calorimetry, was 1346.2 ± 358.0 kcal/d. Thirty participants were excluded based on Cook's distance criteria (Cook's distance of ≥0.008). Previous equations developed by Henry, Schofield, Harris-Benedict (H-B), Yang, and Hong overestimated the BMR of healthy Chinese adults. The present equation displayed the smallest average bias (0.2 kcal/d) between the mBMR and predicted basal metabolic rate (pBMR). The limits of agreement of the present equation from Bland-Altman plots were -514.3 kcal/d and 513.9 kcal/d, which is the most narrow and balanced limit of agreement. Moreover, in the verification of the testing database, the pBMR of the new equation was not significantly different from the mBMR, and the accuracy was 75.6%. Compared with pre-existing equations, the present equation is more applicable to the prediction of BMR in healthy Chinese adults. However, further studies are required to verify the accuracy of this new equation.

Effects of climate change on wind erosion in the three provinces of Northeast China.

The three provinces of Northeast China are crucial to national commodity grain production. Soils in those areas have begun to severely degrade after long-term high-intensity use, with wind erosion as one of the main reasons. Based on meteorological and soil data from 1981 to 2019, we evaluated the spatial-temporal characteristics of wind erosion on bare land in the three provinces of Northeast China by using the revised wind erosion equation (RWEQ), and analyzed the contributions of meteorological factors to wind erosion on bare land. The results showed that, the meteorological factors of wind erosion were overall high in southwestern part and low in northeastern part of the region. In general, wind erosion in the region was substantial, especially in Liaoning. During the 39 years, wind erosion significantly increased throughout the whole year and during the growing season, at a rate of 129 and 105 t·km-2 per decade, respectively. The obvious increase in wind erosion was observed in the northwest Liaoning, Liaohe Plain, and Changbai Mountain area. Wind speed and air temperature were the main factors affecting wind erosion during the year and non-growing season, which contributed less during the growing season when precipitation contributed the most. We concluded that climate change has aggravated soil wind erosion in the three provinces of Northeast China.

Vitamin D Status and Associated Factors of Older Adults in the Cross-Sectional 2015-2017 Survey.

Vitamin D is beneficial for maintaining good health; however, there is a lack of nationally representative data reported, particularly in older adults. To better understand the nutritional status of vitamin D and its influencing factors on Chinese older adults, we adopted stratified random sampling to select serum samples originating from the Chronic Disease and Nutritional Survey Biobank of Chinese Residents in 2015-2017. Serum 25-hydroxyvitamin D (25(OH)D) concentrations were determined by enzyme-linked immunoassay. The OR and PR of associated factors for vitamin D deficiency and insufficiency were calculated. In the study, a total of 6273 participants were included. Median serum 25(OH)D concentration was 18.48 (13.27-24.71) ng/mL. The overall rate of vitamin D deficiency and insufficiency was 58.27% (<20 ng/mL), and the VDD rate was 22.17%, which is worse than 5 years ago by nearly 20%. The likelihood of vitamin D deficiency and insufficiency is increased in women, people aged and above 70 years, ethnic minorities, people living in urban areas, midlands, or western areas, warm or medium temperate zones, with middle school and above education level, and people with abdominal obesity and anemia would increase the possibility of vitamin D deficiency and insufficiency with latitude having the greatest impact on vitamin D deficiency and insufficiency. Overall, vitamin D deficiency and insufficiency are very common in Chinese older adults. They should be encouraged to improve their vitamin D nutritional status through enough sunshine exposure and increasing vitamin D intake through diet or supplements.

Improved performance of quantum dot solar cells by type-II InAs/GaAsSb structure with moderate Sb composition.

We demonstrate improved performance of quantum dot solar cells (QDSCs) by type-II InAs/GaAsSb structure. With a moderate Sb composition of 18% and high quality QDs, a high efficiency of 17.31% under AM1.5 G illumination is achieved, showing an improvement of 11.25% in efficiency relative to type-I InAs/InGaAs QDSC. This improvement can be attributed to a high fill factor (FF) of 72.37% compared to 63% of the latter because the type-II structure effectively suppresses carrier recombination losses in QDs. As Sb composition increases to 24%, the FF maintains at a high level of 72.67%, but the efficiency drops to 17% because the elevation of valence band (VB) in GaAsSb capping layer further enhances the hole confinement. And the confinement reduces external quantum efficiency (EQE) and short-circuit current density (Jsc). These results prove the potential of improving efficiency of QDSCs by type-II structure.

Association between chronic diseases and depression in the middle-aged and older adult Chinese population-a seven-year follow-up study based on CHARLS.

Background: With the aging of the Chinese population, the prevalence of depression and chronic diseases is continually growing among middle-aged and older adult people. This study aimed to investigate the association between chronic diseases and depression in this population. Methods: Data from the China Health and Retirement Longitudinal Study (CHARLS) 2011-2018 longitudinal survey, a 7-years follow-up of 7,163 participants over 45 years old, with no depression at baseline (2011). The chronic disease status in our study was based on the self-report of the participants, and depression was defined by the 10-item Center for Epidemiologic Studies Depression Scale (CES-D-10). The relationship between baseline chronic disease and depression was assessed by the Kaplan-Meier method and Cox proportional hazards regression models. Results: After 7-years follow-up, 41.2% (2,951/7163, 95% CI:40.1, 42.3%) of the participants reported depression. The analysis showed that participants with chronic diseases at baseline had a higher risk of depression and that such risk increased significantly with the number of chronic diseases suffered (1 chronic disease: HR = 1.197; 2 chronic diseases: HR = 1.310; 3 and more chronic diseases: HR = 1.397). Diabetes or high blood sugar (HR = 1.185), kidney disease (HR = 1.252), stomach or other digestive diseases (HR = 1.128), and arthritis or rheumatism (HR = 1.221) all significantly increased the risk of depression in middle-aged and older adult Chinese. Conclusion: The present study found that suffering from different degrees of chronic diseases increased the risk of depression in middle-aged and older adult people, and these findings may benefit preventing depression and improving the quality of mental health in this group.

Aucubin inhibits hepatic stellate cell activation through stimulating Nrf2/Smad7 axis.

AIM: Liver fibrosis may develop into end-stage liver disease if left unprevented. The study is attempting to identify a compound to ameliorate liver fibrosis progression with high efficiency and low toxicity, as well as to analyze its potential molecular mechanism. METHODS: The drug screening was performed using human hepatic stellate cell line LX-2 for identifying the compound as collagen I inhibitor. Primary Human hepatic stellate cells and LX-2 cell line were used to detect the antifibrotic function activity and molecular mechanism analysis in vitro. The CCl4-induced mouse experimental model was used to measure the amelioration in liver fibrosis. RESULTS: This study identified Aucubin, a natural compound, as a candidate for anti-liver fibrosis. Besides, Aucubin could inhibit the collagen I and α-SMA expressions in LX-2 cells and primary human hepatic stellate cells, as well as the cell proliferation. In terms of mechanism, Aucubin could upregulate Smad7 in hepatic stellate cells in a dose-dependent manner and block TGF-ß signaling. We also found that Nrf2 might be a direct target for the action of Aucubin, whose activation was necessary for Smad7 upregulation. In an in-vivo mouse model, Aucubin efficiency ameliorated the progression of CCl4-induced liver fibrosis, and reduced the hepatic levels of collagen deposition, transaminase and inflammatory cytokines. CONCLUSION: Capable of inhibiting the activation of hepatic stellate cells in vitro and in vivo, Aucubin may be a potential therapeutic candidate for liver fibrosis, which is dependent on the suppression of TGF-ß signaling through stimulating Nrf2/Smad7 axis.

Sodium content targets for pre-packaged foods, China: a quantitative study and proposal.

Objective: To determine the contribution of pre-packaged foods to population sodium intake in China, and to propose sodium content targets for food subcategories used for the World Health Organization's (WHO's) global sodium benchmarks. Methods: The impact of four different approaches to reducing the sodium content of pre-packaged foods on population sodium intake was estimated using data from national databases covering the nutrient content and ingredients of 51 803 food products and food consumption by 15 670 Chinese adults. We recategorized food products using a food categorization framework developed for WHO's global sodium benchmarks and adapted for China-specific foods. Findings: Pre-packaged foods, including condiments, contributed 1302.5 mg/day of sodium intake per adult in 2021, accounting for 30.1% of population sodium intake in China. Setting maximum sodium content levels using a 90th-percentile target would reduce sodium intake from pre-packaged foods by 96.2 mg/day, corresponding to a 1.9% reduction in population intake. Using the 75th-percentile, a fixed 20% reduction and WHO benchmark targets would further reduce intake by 262.0 mg/day (5.2% population intake), 302.8 mg/day (6.0% population intake) and 701.2 mg/day per person (13.9% population intake), respectively. Maximum sodium content levels based on revised 20% reduction targets were proposed because they should result in substantial and acceptable reductions in sodium content for most food subcategories: overall sodium intake would decline by 305.0 mg/day per person, and population intake by 6.1%. Conclusion: This study provides the scientific rationale for government policy on setting targets for food sodium content in China. Simultaneous action on discretionary salt use should also be taken.

Ultra-high thermal stability InAs/GaAs quantum dot lasers grown on on-axis Si (001) with a record-high continuous-wave operating temperature of 150 °C.

Direct epitaxial growth of group III-V light sources with excellently thermal performance on silicon photonics chips promises low-cost, low-power-consumption, high-performance photonic integrated circuits. Here, we report on the achievement of ultra-high thermal stability 1.3 µm InAs/GaAs quantum dot (QD) lasers directly grown on an on-axis Si (001) with a record-high continuous-wave (CW) operating temperature of 150 °C. A GaAs buffer layer with a low threading dislocation density (TDD) of 4.3 × 106 cm-2 was first deposited using an optimized three-step growth method by molecular beam epitaxy. Then, an eight-layer QD laser structure with p-type modulation doping to enhance the temperature stability of the device was subsequently grown on the low TDD Si-based GaAs buffer layer. It is shown that the QD laser exhibits the ultra-high temperature stability with a characteristic temperature T0=∞ and T1=∞ in the wide temperature range of 10-75 °C and 10-140 °C, respectively. Moreover, a maximum CW operating temperature of up to 150 °C and a pulsed operating temperature of up to 160 °C are achieved for the QD laser. In addition, the QD laser shows a high CW saturation power of 50 mW at 85 °C and 19 mW at 125 °C, respectively.

The heat stress during anthesis and the grain-filling period of spring maize in Northeast China is projected to increase toward the mid-21st century.

BACKGROUND: Against the background of global warming, heat stress has become more frequent, which adversely affects the growth and development of spring maize plants in Northeast China. To adapt the regional maize production to climate change, it is imperative to understand the spatio-temporal characteristics of heat stress. In the present study, we analyzed three of the indices for heat stress, including the number of heat stress days, heating degree days (HDD, the total heat degree-days during critical stages), and the percentage of stations with heat stress. RESULTS: From 1981 to 2019, the number of heat stress days varied greatly among the study years, ranging from 0 to 14 and 27 days, respectively. The average HDD was 7.8 and 5.0 °C day from 1981 to 2000, respectively, and the main hot-spots of heat stress occurred in the southwest regions. Moreover, compared with 1981-2000, the region of HDD during anthesis higher than 10 °C day in 2041-2060 under the SSP1-2.6 and SSP5-8.5 climate scenarios increased by 9.1-50.1% and 0.1-28.6%. The average HDD during the critical stages from 2041 to 2060 increased under the SSP5-8.5 climate scenario, being 1.5 times higher than that during 1981-2000. HDD during maize anthesis and the grain-filling period showed an overall increasing trend with years. About 19% and 58% of the study locations showed heat stress during the past 39 years, respectively. CONCLUSION: Heat stress during anthesis and the grain-filling period for spring maize in Northeast China is projected to increase toward the mid-21st century. © 2023 Society of Chemical Industry.

Significantly enhanced performance of InAs/GaAs quantum dot lasers on Si(001) via spatially separated co-doping.

We report the significantly enhanced performance of InAs/GaAs quantum dot (QD) lasers on Si(001) by spatially separated co-doping, including n-doping in the QDs and p-doping in the barrier layers simultaneously. The QD lasers are a ridge waveguide of 6 × 1000 µm2 containing five InAs QD layers. Compared with p-doped alone laser, the co-doped laser exhibits a large reduction in threshold current of 30.3% and an increase in maximum output power of 25.5% at room temperature. In the range of 15°C-115°C (under 1% pulse mode), the co-doped laser shows better temperature stability with higher characteristic temperatures of threshold current (T0) and slope efficiency (T1). Furthermore, the co-doped laser can maintain stable continuous-wave ground-state lasing up to a high temperature of 115°C. These results prove the great potential of co-doping technique for enhancing silicon-based QD laser performances towards lower power consumption, higher temperature stability, and higher operating temperature, to boost the development of high-performance silicon photonic chips.