A narrative review of anxiety regulation in PhD students based on Green model.

To gain a better understanding of the factors that contribute to anxiety among PhD students and the reasons for poor regulation in the current situation, this paper analyses the existing literature on anxiety among PhD students using Green's model. It also compares and evaluates various methods of regulating anxiety. The literature review to extract information on the causes and levels of anxiety, methods and outcomes of anxiety intervention and regulation, and to make comparisons. The study reveals that the phenomenon of PhD students' anxiety has intensified globally in recent years, especially after the end of the epidemic. PhD students experience anxiety due to research pressure, economic pressure, future development, and interpersonal pressure. The main influencing factors are currently the relationship with the supervisor, development prospects, social support, and peer comparison. Among the stress relief methods, the regulation of self-relaxation was found to have better effects on mild anxiety, such as positive thinking, meditation, yoga and physical exercise can be helpful for emotion release then help focus on problem solved. Whereas severe anxiety may require institutional and pharmacological support, also including using psychological therapy such as behavioral cognitive therapy and systematic desensitization methods. For university, competence to provide course-assisted guidance, such as writing groups, peer support, and time management, is also important. Academic communities should pay attention to the guidance on academic fairness. However, PhD students are often unaware of the resources available to them for coping with stress and may not take the initiative to seek psychological counseling or institutional assistance. Therefore, PhD students should receive support from various sources, be guided to express their thoughts, and receive additional education and academic assistance to manage stress. This will enhance their confidence and aid in improving their scientific research.

Novel magnetic compression technique for the treatment of postoperative anastomotic stenosis in rectal cancer: A case report.

BACKGROUND: The treatment of postoperative anastomotic stenosis after excision of rectal cancer is challenging. Endoscopic balloon dilation and radial incision are not effective in all patients. We present a new endoscopy-assisted magnetic compression technique (MCT) for the treatment of rectal anastomotic stenosis. We successfully applied this MCT to a patient who developed an anastomotic stricture after radical resection of rectal cancer. CASE SUMMARY: A 50-year-old man had undergone laparoscopic radical rectal cancer surgery at a local hospital 5 months ago. A colonoscopy performed 2 months ago indicated that the rectal anastomosis was narrow due to which ileostomy closure could not be performed. The patient came to the Magnetic Surgery Clinic of the First Affiliated Hospital of Xi'an Jiaotong University after learning that we had successfully treated patients with colorectal stenosis using MCT. We performed endoscopy-assisted magnetic compression surgery for rectal stenosis. The magnets were removed 16 d later. A follow-up colonoscopy performed after 4 months showed good anastomotic patency, following which, ileostomy closure surgery was performed. CONCLUSION: MCT is a simple, non-invasive technique for the treatment of anastomotic stricture after radical resection of rectal cancer. The technique can be widely used in clinical settings.

Chemoselectivity Switch between Enantioselective [2,3]-Wittig Rearrangement and Conia-Ene-Type Reactions of Propargyloxyoxindoles.

Despite the existence of three competing reactions for propargyloxyoxindoles, we report a chemoselectivity switch between enantioselective propargyl [2,3]-Wittig rearrangement and Conia-ene-type reactions, with suppression of the [1,2]-Wittig-type rearrangement. Using C1-symmetric imidazolidine-pyrroloimidazolone pyridine as the ligand and Ni(acac)2 as the Lewis acid, diverse 3-hydroxy 3-substituted oxindoles containing allenyl groups were obtained in up to 98% yield and 99% ee via asymmetric propargyl [2,3]-Wittig rearrangement. In the presence of AgOTf-Duanphos, chiral spiro dihydrofuran oxindoles were given in up to 98% yield and 91% ee through a Conia-ene-type reaction.

Heat stress reprograms herbivory-induced defense responses in potato plants.

Climate change is predicted to increase the occurrence of extreme weather events such as heatwaves, which may thereby impact the outcome of plant-herbivore interactions. While elevated temperature is known to directly affect herbivore growth, it remains largely unclear if it indirectly influences herbivore performance by affecting the host plant they feed on. In this study, we investigated how transient exposure to high temperature influences plant herbivory-induced defenses at the transcript and metabolic level. To this end, we studied the interaction between potato (Solanum tuberosum) plants and the larvae of the potato tuber moth (Phthorimaea operculella) under different temperature regimes. We found that P. operculella larvae grew heavier on leaves co-stressed by high temperature and insect herbivory than on leaves pre-stressed by herbivory alone. We also observed that high temperature treatments altered phylotranscriptomic patterns upon herbivory, which changed from an evolutionary hourglass pattern, in which transcriptomic responses at early and late time points after elicitation are more variable than the ones in the middle, to a vase pattern. Specifically, transcripts of many herbivory-induced genes in the early and late defense stage were suppressed by HT treatment, whereas those in the intermediate stage peaked earlier. Additionally, we observed that high temperature impaired the induction of jasmonates and defense compounds upon herbivory. Moreover, using jasmonate-reduced (JA-reduced, irAOC) and -elevated (JA-Ile-elevated, irCYP94B3s) potato plants, we showed that high temperature suppresses JA signaling mediated plant-induced defense to herbivore attack. Thus, our study provides evidences on how temperature reprograms plant-induced defense to herbivores.

The human brain deals with violating general color or depth knowledge in different time courses.

Utilizing the high temporal resolution of event-related potentials (ERPs), we compared the time course of processing incongruent color versus 3D-depth information. Participants were asked to judge whether the food color (color condition) or 3D structure (3D-depth condition) was congruent or incongruent with their previous knowledge and experience. The behavioral results showed that the reaction times in the congruent 3D-depth condition were slower than those in the congruent color condition. The reaction times in the incongruent 3D-depth condition were slower than those in the incongruent color condition. The ERP results showed that incongruent color stimuli induced a larger N270, larger P300, and smaller N400 components in the fronto-central region than the congruent color stimuli. Incongruent 3D-depth stimuli induced a smaller N1 in the occipital region, larger P300 and smaller N400 in the parietal-occipital region than congruent 3D-depth stimuli. The time-frequency analysis found that incongruent color stimuli induced a larger theta band (360-580 ms) activation in the fronto-central region than congruent color stimuli. Incongruent 3D-depth stimuli induced larger alpha and beta bands (240-350 ms) activation in the parietal region than congruent 3D-depth stimuli. Our results suggest that the human brain deals with violating general color or depth knowledge in different time courses. We speculate that the depth perception conflict was dominated by solving the problem with visual processing, whereas the color perception conflict was dominated by solving the problem with semantic violation.

Proactive resistance management for sustaining the efficacy of RNA interference for pest control.

Biopesticides based on RNA interference (RNAi) took a major step forward with the first registration of a sprayable RNAi product, which targets the world's most damaging potato pest. Proactive resistance management is needed to delay the evolution of resistance by pests and sustain the efficacy of RNAi biopesticides.

Genomic identification and evolutionary analysis of chemosensory receptor gene families in two Phthorimaea pest species: insights into chemical ecology and host adaptation.

BACKGROUND: Insects rely on sophisticated sensitive chemosensory systems to sense their complex chemical environment. This sensory process involves a combination of odorant receptors (ORs), gustatory receptors (GRs) and ionotropic receptors (IRs) in the chemosensory system. This study focused on the identification and characterization of these three types of chemosensory receptor genes in two closely related Phthorimaea pest species, Phthorimaea operculella (potato tuber moth) and Phthorimaea absoluta (tomato leaf miner). RESULTS: Based on manual annotation of the genome, we identified a total of 349 chemoreceptor genes from the genome of P. operculella, including 93 OR, 206 GR and 50 IR genes, while for P. absoluta, we identified 72 OR, 122 GR and 46 IR genes. Through phylogenetic analysis, we observed minimal differences in the number and types of ORs and IRs between the potato tuber moth and tomato leaf miner. In addition, we found that compared with those of tomato leaf miners, the gustatory receptor branch of P. operculella has undergone a large expansion, which may be related to P. absoluta having a narrower host range than P. operculella. Through analysis of differentially expressed genes (DEGs) of male and female antennae, we uncovered 45 DEGs (including 32ORs, 9 GRs, and 4 IRs). CONCLUSIONS: Our research provides a foundation for exploring the chemical ecology of these two pests and offers new insights into the dietary differentiation of lepidopteran insects, while simultaneously providing molecular targets for developing environmentally friendly pest control methods based on insect chemoreception.

Presence of Multiple Genetic Mutations Related to Insecticide Resistance in Chinese Field Samples of Two Phthorimaea Pest Species.

Potatoes hold the distinction of being the largest non-cereal food crop globally. The application of insecticides has been the most common technology for pest control. The repeated use of synthetic insecticides of the same chemical class and frequent applications have resulted in the emergence of insecticide resistance. Two closely related pests that feed on potato crops are the potato tuber moth, Phthorimaea operculella, and the tomato leafminer, Phthorimaea absoluta (syn. Tuta absoluta). Previous studies indicated the existence of insecticide resistance to various classes of insecticides including organophosphates, carbamates, and pyrethroids in field populations of P. operculella and P. absoluta. However, the exact mechanisms of insecticide resistance in P. operculella and to a lesser extent P. absoluta remain still poorly understood. Detecting resistance genotypes is crucial for the prediction and management of insecticide resistance. In this study, we identified multiple genetic mutations related to insecticide resistance in two species of Phthorimaea. An unexpected genetic divergence on target-site mutations was observed between P. operculella and P. absoluta. Three mutations (A201S, L231V, and F290V) in Ace1 (acetylcholinesterase), four mutations (M918T, L925M, T928I, and L1014F) in VGSC (voltage-gated sodium channel), and one mutation (A301S) in RDL (GABA-gated chloride channel) have been detected with varying frequencies in Chinese P. absoluta field populations. In contrast, P. operculella field populations showed three mutations (F158Y, A201S, and L231V) in Ace1, one mutation (L1014F) in VGSC at a lower frequency, and no mutation in RDL. These findings suggest that pyrethroids, organophosphates, and carbamates are likely to be ineffective in controlling P. absoluta, but not P. operculella. These findings contributed to a deeper understanding of the presence of target-site mutations conferring resistance to commonly used (and cheap) classes of insecticides in two closely related potato pests. It is recommended to consider the resistance status of both pests for the implementation of resistance management strategies in potatoes.

Prevalence and risk factors of cognitive frailty among pre-frail and frail older adults in nursing homes.

BACKGROUND: The purpose of this research was to stratify the level of frailty to examine the risk factors associated with reversible cognitive frailty (RCF) and potentially reversible cognitive frailty (PRCF) in nursing homes to provide a basis for hierarchical management in different stages of frailty. METHODS: The study was a cross-sectional study conducted from September to November 2022; 504 people were selected by stratified random sampling after convenience selection from the Home for the Aged Guangzhou. The structured questionnaire survey was conducted through face-to-face interviews using the general data questionnaire, Fried Frailty Phenotype, Montreal Cognitive Assessment Scale. RESULTS: In total, 452 individuals were included for analysis. A total of 229 cases (50.7%) were PRCF, 70 (15.5%) were RCF. Multivariate logistic regression analysis showed that in pre-frailty, the Geriatric Depression Scale (GDS-15) score (odds ratio (OR) 1.802; 95% CI 1.308-2.483), Instrumental Activities of Daily Living Scale (IADL) score (0.352; 0.135-0.918) and energy (0.288; 0.110-0.755) were influencing factors of RCF. GDS-15 score (1.805; 1.320-2.468), IADL score (0.268; 0.105-0.682), energy (0.377; 0.150-0.947), lack of intellectual activity (6.118; 1.067-35.070), admission time(>3 years) (9.969; 1.893-52.495) and low education (3.465; 1.211-9.912) were influencing factors of PRCF. However, RCF with frailty was associated with the Short-Form Mini-Nutritional Assessment (MNA-SF) score (0.301; 0.123-0.739) and low education time (0 ~ 12 years) (0.021; 0.001-0.826). PRCF with frailty was associated with age (1.327; 1.081-1.629) and weekly exercise time (0.987; 0.979-0.995). CONCLUSIONS: The prevalence of RCF and PRCF was high among pre-frail and frail older adults in nursing homes. Different levels of frailty had different influencing factors for RCF and PRCF. Depression, daily living ability, energy, intellectual activity, admission time, education level, nutrition status, age and exercise time were associated with RCF and PRCF. Hierarchical management and intervention should be implemented for different stages of frailty to prevent or delay the progression of cognitive frailty.

Knocking down a DNA demethylase gene affects potato plant defense against a specialist insect herbivore.

DNA demethylase (DML) is involved in plant development and responses to biotic and abiotic stresses; however, its role in plant-herbivore interaction remains elusive. Here, we found that herbivory by the potato tuber moth, Phthorimaea operculella, rapidly induced the genome-wide DNA methylation and accumulation of DML gene transcripts in potato plants. Herbivory induction of DML transcripts was suppressed in jasmonate-deficient plants, whereas exogenous application of methyl jasmonate (MeJA) improved DML transcripts, indicating that the induction of DML transcripts by herbivory is associated with jasmonate signaling. Moreover, P. operculella larvae grew heavier on DML gene (StDML2) knockdown plants than on wild-type plants, and the decreased biosynthesis of jasmonates in the former may be responsible for this difference, since the larvae feeding on these two genotypes supplemented with MeJA showed similar growth. In addition, P. operculella adult moths preferred to oviposit on StDML2 knockdown plants than on wild-type plants, which was associated with the reduced emission of ß-caryophyllene in the former. In addition, supplementing ß-caryophyllene to these two genotypes further disrupted moths' oviposit choice preference for them. Interestingly, in StDML2 knockdown plants, hypermethylation was found at the promoter regions for the key genes StAOS and StAOC in the jasmonate biosynthetic pathway, as well as for the key gene StTPS12 in ß-caryophyllene production. Our findings suggest that knocking down StDML2 can affect herbivore defense via jasmonate signaling and defense compound production in potato plants.

Accelerating Sulfur Redox Kinetics by Electronic Modulation and Drifting Effects of Pre-Lithiation Electrocatalysts.

Efficient catalyst design is crucial for addressing the sluggish multi-step sulfur redox reaction (SRR) in lithium-sulfur batteries (LiSBs), which are among the promising candidates for the next-generation high-energy-density storage systems. However, the limited understanding of the underlying catalytic kinetic mechanisms and the lack of precise control over catalyst structures pose challenges in designing highly efficient catalysts, which hinder the LiSBs' practical application. Here, drawing inspiration from the theoretical calculations, the concept of precisely controlled pre-lithiation SRR electrocatalysts is proposed. The dual roles of channel and surface lithium in pre-lithiated 1T'-MoS2 are revealed, referred to as the "electronic modulation effect" and "drifting effect", respectively, both of which contribute to accelerating the SRR kinetics. As a result, the thus-designed 1T'-Lix MoS2 /CS cathode obtained by epitaxial growth of pre-lithiated 1T'-MoS2 on cubic Co9 S8 exhibits impressive performance with a high initial specific capacity of 1049.8 mAh g-1 , excellent rate-capability, and remarkable long-term cycling stability with a decay rate of only 0.019% per cycle over 1000 cycles at 3 C. This work highlights the importance of precise control in pre-lithiation parameters and the synergistic effects of channel and surface lithium, providing new valuable insights into the design and optimization of SRR electrocatalysts for high-performance LiSBs.

Comparison between screw fixation and plate fixation via sinus tarsi approach for displaced intra-articular calcaneal fractures: a systematic review and meta-analysis.

BACKGROUND: Optimal surgical fixation for displaced intra-articular calcaneal fractures (DIACF) remains a subject of debate, particularly regarding the superiority between screw fixation and plate fixation via the sinus tarsi approach (STA). This review aims to determine the preferred treatment for DIACF and compare the outcomes of minimally invasive surgery options. METHODS: Our study involved thorough searches across multiple electronic databases, including PubMed, Cochrane, Embase, and Web of Science, to identify all relevant publications on distal intra-articular fractures of the calcaneus (DIACFs) that were fixed using cannulated screws or plates via STA. Through a comprehensive meta-analysis, we evaluated several outcomes, including post-operative function, radiological measurements, and complications. RESULT: A total of 728 patients from 7 studies met the inclusion criteria. Among them, 435 patients underwent screw fixation via STA, and 373 patients underwent plate fixation via STA. The study found no statistically significant differences between the screw fixation and the plate fixation via sinus tarsi approach (STA) in terms of AOFAS scores, Bohler's angle, Gissane's angle, sural nerve injury, secondary subtalar arthrodesis and reoperation. Compared with screw fixation, plate fixation via STA can reduce reduction loss of Bohler's angle (WMD = - 1.64, 95% CI = [- 2.96, - 0.31], P = 0.06, I2 = 59%), lower the incidence of fixation failure (OR = 0.32, 95% CI = [0.13, 0.81], P = 0.78, I2 = 0%), and decrease intra-articular step-off (WMD = - 0.52, 95% CI = [- 0.87, - 0.17], P = 0.66, I2 = 0%). CONCLUSIONS: Plate fixation demonstrates superior capability in restoring calcaneal width, maintaining Bohler's angle, and minimizing intra-articular step-off, thereby maintaining better reduction of the subtalar articular surface. In addition, plate fixation exhibits the modest complication rate and a low incidence of fixation failure. Therefore, we recommend the use of plate fixation through the STA, especially for complex and comminuted intra-articular calcaneal fractures.

Frameworked Electrolytes: A Pathway Towards Solid Future of Batteries.

All-solid-state batteries (ASSBs) represent a highly promising next-generation energy storage technology owing to their inherently high safety, device reliability, and potential for achieving high energy density in the post-ara of lithium-ion batteries, and therefore extensive searches are ongoing for ideal solid-state electrolytes (SSEs). Though promising, there is still a huge barrier that limits the large-scale applications of ASSBs, where there are a couple of bottleneck technical issues. In this perspective, a novel category of electrolytes known as frameworked electrolytes (FEs) are examined, where the solid frameworks are intentionally designed to contain 3D ionic channels at sub-nano scales, rendering them macroscopically solid. The distinctive structural design of FEs gives rise to not only high ionic conductivity but also desirable interfaces with electrode solids. This is achieved through the presence of sub-nano channels within the framework, which exhibit significantly different ion diffusion behavior due to the confinement effect. This perspective offers a compelling insight into the potential of FEs in the pursuit of ASSBs, where FEs offer an exciting opportunity to overcome the limitations of traditional solid-state electrolytes and propel the development of ASSBs as the holy grail of energy storage technology.

Comparison of arthroscopic and open Brostrom-Gould surgery for chronic ankle instability: a systematic review and meta-analysis.

BACKGROUND: Approximately 20% of acute ankle sprains progress to chronic lateral ankle instability (CLAI) requiring surgical intervention. There has been growing interest among surgeons regarding whether arthroscopic techniques can replace open Brostrom-Gould surgery in treating CLAI. The purpose of this study was to pool the results of multiple studies comparing the treatment effects of these two fixation approaches. METHODS: Our study involved thorough searches across multiple electronic databases, including PubMed, Cochrane, Embase, and Web of Science, to identify all relevant publications on CLAI that were repaired using the arthroscopic or open Broström-Gould technique. Through a comprehensive meta-analysis, we evaluated several outcomes, including post-operative function, radiological measurements, complications, and time efficiency. RESULT: A total of 686 patients from 11 studies were included in the analysis. Among them, 351 patients underwent open repair, and 335 underwent arthroscopic Brostrom-Gould surgery. The present study revealed that arthroscopic and open Brostrom-Gould techniques demonstrated no significant differences in talar tilt, talar anterior translation, complication rate, and time to return to previous level of activity. Furthermore, no significant differences were observed in AOFAS, K-P, VAS, and Tegner scores at the 2-year follow-up. However, significant differences were noted between the two surgical approaches in terms of early weight-bearing (WMD = - 1.33 weeks, 95% CI = [- 1.91, - 0.76], P = 0.17, I2 = 40%), as well as AOFAS scores (WMD = 1.00, 95% CI = [0.05, 1.95], P = 0.73, I2 = 0%), K-P scores (WMD = 1.57, 95% CI = [0.49, 2.64], P = 0.15, I2 = 47%), and VAS scores (WMD = - 0.15, 95% CI = [- 0.60, 0.29], P < 0.08, I2 = 61%) within the first postoperative year. CONCLUSIONS: Our findings support that arthroscopic repair yields comparable outcomes to open surgery. Consequently, we advocate for adopting arthroscopic repair as a preferred alternative to the conventional open Broström-Gould procedure for treating chronic lateral ankle instability.

Management of cognitive frailty: A network meta-analysis of randomized controlled trials.

OBJECTIVES: We aimed to compare the effectiveness of interventions in cognitive function and frailty status and rank these interventions. METHODS: Data Sources-We searched PubMed, Embase, CINAHL, PsycINFO, Web of Science, Cochrane Library, Central Register of Controlled Trials (CENTRAL), CNKI, Wanfang, VIP and Google scholar. Data synthesis-The risk of bias was assessed using the Cochrane risk bias assessment tool. Statistical heterogeneity was assessed using the Chi-square test and quantified by I2 . The results were pooled using the standardized mean difference (SMD). The rank probability for each intervention was calculated using the surface under the cumulative ranking curve (SUCRA). Additionally, the quality of the evidence was evaluated using the GRADE approach. RESULTS: A total of 10 randomized controlled trials (RCTs) involving 1110 patients were included in our analysis. The network map of cognitive function comprised 9 RCTs with 1347 participants, examining eight different interventions. Nutritional support (SUCRA = 99.9%, SMD = 3.02, 95% CI: 2.53, 3.51) may be the most effective intervention to improve cognitive function. The network map of frailty (including 9 RCTs with 1017 participants and 9 interventions) suggested that multicomponent exercises (SUCRA = 96.4%, SMD = -5.10, 95% CI: -5.96, -4.23) tended to have a greater effect. CONCLUSIONS: Community-based multicomponent exercises have shown significant benefits for improving cognitive function and frailty status in older adults, with moderate certainty. For hospitalized older patients with Cognitive frailty (CF), current evidence suggests that nutritional support yields the most improvement. Additionally, aerobic exercise and dual-task training have proven effective in managing CF. Further studies are needed to validate these preliminary findings and exploring more accessible and effective physical and cognitive interventions to prevent CF in aging.

Pest management of postharvest potatoes: lethal, sublethal and transgenerational effects of the ectoparasitic mite Pyemotes zhonghuajia on the potato worm Phthorimaea operculella.

BACKGROUND: Potato, Solanum tuberosum, is one of the most important food crops in the world, playing a significant role in global food security. However, many potato industries and farms may suffer losses of tuber yield and quality in storage due to lepidopteran pests. Here, we evaluated the effectiveness of an ectoparasitic idiobiont mite Pyemotes zhonghuajia in the biological control of the potato tuber moth (PTM) Phthorimaea operculella by determining the lethal, sublethal (nonconsumptive) and transgenerational effects of P. zhonghuajia of various population densities and exposure durations on PTM survival, development and reproduction. RESULTS: Pyemotes zhonghuajia females were capable of killing all instar stages of PTM, while resistance to mite parasitism increased with the development of PTM life stage. The mortality of mature larvae (i.e., fourth instar) and pupae increased with increasing mite density and exposure duration. P. zhonghuajia imposed significant negative sublethal impacts on PTM pupation rate, female fecundity and adult longevity but not on immature development. The sublethal stress was transgenerational, resulting in lower reproduction in the offspring generation. CONCLUSION: P. zhonghuajia induces lethal, sublethal and transgenerational effects and significantly decreases PTM survival and reproductive out, demonstrating its high efficiency in the biological control of PTM. Our study provides insight into the mechanisms underlying the nonconsumptive effects of parasitism in an ectoparasite-host system and delivers critical information for the design and implementation of augmentative releases of P. zhonghuajia in the biological control of PTM in potato storage. © 2023 Society of Chemical Industry.

Quasi-Copper-Mers Enable High-Performance Catalysis for CO2 Reduction.

As the atmospheric carbon dioxide (CO2 ) level keeps hitting the new record, humanity is facing an ever-daunting challenge to efficiently mitigate CO2 from the atmosphere. Though electrochemical CO2 reduction presents a promising pathway to convert CO2 to valuable fuels and chemicals, the general lack of suitable electrocatalysts with high activity and selectivity severely constrains this approach. Herein, a novel class of electrocatalysts is investigated, the quasi-copper-mers, in which the CuN4 rather than Cu atom itself serve as the basic building block. The respective quasi-copper-monomers, -dimers, and -trimers hosted in a graphene-like substrate are first synthesized and then performed both experimental characterization and density functional theory (DFT) calculations to examine their atomic structures, evaluate their electrocatalytical performance and understand their underlying mechanisms. The experimental results show that the quasi-copper-trimers not only outperform the quasi-copper-dimer and quasi-copper-monomer when catalyzing CO2 to CO, it also shows a superior selectivity against the competing hydrogen evolution reaction (HER). The DFT calculations not only support the experimental observations, but also reveal the volcano curve and the physical origin for the qausi-copper-trimer superiority. The present work thus presents a new strategy in the design of high-performance electrocatalysts with high activity and selectivity.

Optical power degradation mechanisms in 271†nm AlGaN-based deep ultraviolet light-emitting diodes.

The degradation of AlGaN-based UVC LEDs under constant temperature and constant current stress for up to 500 hrs was analyzed in this work. During each degradation stage, the two-dimensional (2D) thermal distributions, I-V curves, optical powers, combining with focused ion beam and scanning electron microscope (FIB/SEM), were thoroughly tested and analyzed the properties and failure mechanisms of UVC LEDs. The results show that: 1) the opto-electrical characteristics measured before/during stress indicate that the increased leakage current and the generation of stress-induced defects increase the non-radiative recombination in the early stress stage, resulting in a decrease in optical power; 2) the increase of temperature caused by the deterioration of the Cr/Al layer of p-metal after 48 hrs of stress aggravates the optical power in UVC LEDs. The 2D thermal distribution in conjunction with FIB/SEM provide a fast and visual way to precisely locate and analyze the failure mechanisms of UVC LEDs.