Transcriptional regulation of TacL-mediated lipoteichoic acids biosynthesis by ComE during competence impacts pneumococcal transformation.

Competence development is essential for bacterial transformation since it enables bacteria to take up free DNA from the surrounding environment. The regulation of teichoic acid biosynthesis is tightly controlled during pneumococcal competence; however, the mechanism governing this regulation and its impact on transformation remains poorly understood. We demonstrated that a defect in lipoteichoic acid ligase (TacL)-mediated lipoteichoic acids (LTAs) biosynthesis was associated with impaired pneumococcal transformation. Using a fragment of tacL regulatory probe as bait in a DNA pulldown assay, we successfully identified several regulatory proteins, including ComE. Electrophoretic mobility shift assays revealed that phosphomimetic ComE, but not wild-type ComE, exhibited specific binding to the probe. DNase I footprinting assays revealed the specific binding sequences encompassing around 30 base pairs located 31 base pairs upstream from the start codon of tacL. Expression of tacL was found to be upregulated in the ΔcomE strain, and the addition of exogenous competence-stimulating peptide repressed the tacL transcription in the wild-type strain but not the ΔcomE mutant, indicating that ComE exerted a negative regulatory effect on the transcription of tacL. Mutation in the JH2 region of tacL upstream regulatory sequence led to increased LTAs abundance and displayed higher transformation efficiency. Collectively, our work identified the regulatory mechanisms that control LTAs biosynthesis during competence and thereby unveiled a repression mechanism underlying pneumococcal transformation.

Thrombosis density ratio can predict the occurrence of pulmonary embolism and post-thrombotic syndrome in lower-extremity deep vein thrombosis patients.

OBJECTIVE: Deep vein thrombosis (DVT) formation of lower extremities can lead to serious complications including pulmonary embolism (PE) and chronic post-thrombotic syndrome (PTS). We aimed to explore the relationship between the ratio of thrombotic density and the occurrence of PE and PTS in patients with DVT of the lower extremities. METHODS: A retrospective analysis was conducted in patients who performed computed tomography venography, dividing into DVT with PE group (54 patients) and DVT-alone group (34 patients), The clinical data were recorded. Univariate and multivariate logistic regression analysis were used to analysis variables associated with PE. The ability of thrombosis density ratio and Wells score to diagnose PE was evaluated by using the receiver operating characteristic curve (ROC) area under the curve (AUC). According to the treatment and follow-up results, subgroup analysis was performed, and the Villata score was used to determine the presence or absence of PTS and its severity. RESULTS: Compare with the DVT-alone group, more patients had dyspnea and chest pain in the DVT with PE group. DVT with PE group had lower the percentage of neutrophils, white blood cell count and platelet count, while had higher blood cell count, D-dimer, wells score, thrombus and thrombus density ratio. Multivariate logistic analysis showed that percentage of neutrophils (OR(95% CIs)=1.15 (1.01,1.31), P = 0.040), platelets (OR(95% CIs)=0.96 (0.93,0.99), P = 0.011), and thrombus density ratio (OR(95% CIs)=5.99 (1.96,18.35), P = 0.002) are independent predictors of PE. The Wells score and thrombosis density ratio were consistent in the diagnostic efficacy of PE. In the subgroup analysis, there was a relevance between the ratio of thrombosis density and the Villalta score. CONCLUSION: Percentage of neutrophils, platelets, and thrombus density ratio are independent predictors of PE. The thrombosis density of DVT patients may be an index to predict the risk of PE and PTS in DVT patients.

Perceived stigma in burn survivors: Associations with resourcefulness and alexithymia.

OBJECTIVE: Burn survivors often have severe scarring and distorted body image, and they are commonly given new perceptions and even receive a variety of negative labels from individuals, families and society. This study aimed to explore the association between stigma, resourcefulness and alexithymia, and identifies whether resourcefulness in burn survivors is mediating the relationship between resourcefulness and alexithymia. METHOD: This correlational study was conducted from December 2021 to July 2022 in a comprehensive tertiary Grade A hospital in Ningxia, China. A convenience sample of 159 burn survivors was recruited. Data were collected using demographics, Social Impact Scale(SIC),Toronto Alexithymia Scale, and Resourcefulness Scale (RS). Descriptive analysis, Hierarchical Regression analysis, Pearson Correlation analysis, and Mediation analysis were used for data analysis. RESULTS: Finally, a data set of 148 responses was determined for analysis. The effective rate was 95.9%. We found significant correlation between stigma, resourcefulness and alexithymia. Sociodemographic characteristics (gender, spouse states), clinical characteristics (body surface burned area, scar areas), resourcefulness and alexithymia of burn survivors were significant predictors of stigma among burn survivors. The mediating effect of resourcefulness between stigma and alexithymia in burns survivors accounted for 36.03% of the total effect. CONCLUSION: Resourcefulness partially mediates the relationship between stigma and alexithymia. These findings suggest medical staff should strengthen the management of the mental health of burn survivors and eliminate the negative cognition and tendency of burn survivors by regularly promoting stigma counseling measures based on cognitive behavioral therapy. Based on the resourcefulness theory, psychological counseling and intervention are carried out in various ways to fully mobilize their internal factors for positive emotional regulation and enhance the ability of individuals to cope with adversity. In addition, an attempt was made to establish an "anti-stigma coalition" or "peer support group" for burn survivors to provide networked information support and emotional support to facilitate further the smooth return of patients to their families and society.

Metabolic syndrome and metastatic prostate cancer correlation study, a real-world study in a prostate cancer clinical research center, Xinjiang, China.

Objective: The aim of this study was to investigate the relevance of metabolic syndrome (MetS) and metabolic scores to the occurrence, progression and prognosis of metastatic prostate cancer (mPCA), assessing the definition of the variables of metabolic syndrome, and the potential mechanisms of MetS and mPCA. Methods: Data were obtained from the database of prostate cancer follow-up at the Urology Centre of the First Affiliated Hospital of Xinjiang Medical University (N=1303). After screening by inclusion and exclusion criteria, clinical data of 190 patients diagnosed with mPCA by pathology and imaging from January 2010 to August 2021 were finally included, including 111 cases in the MetS group and 79 cases in the Non-MetS group. Results: The MetS group was higher than the Non-MetS group: T stage, Gleasson score, initial PSA, tumor load, PSA after 7 months of ADT (P<0.05),with a shorter time to progression to CRPC stage(P<0.05)[where the time to progression to CRPC was relatively shorter in the high metabolic score subgroup of the MetS group than in the low subgroup (P<0.05)].Median survival time was significantly shorter in the MetS group than in the Non-MetS group (P<0.05),and there was a correlation with metabolic score, with the higher metabolic score subgroup having a lower survival time than the lower metabolic score subgroup (P<0.05). Conclusion: Those with mPCA combined with MetS had lower PSA remission rates, more aggressive tumors, shorter time to progression to CRPC and shorter median survival times than those with mPCA without MetS.Tumour progression and metabolic score showed a positive correlation, predicting that MetS may promote the progression of mPCA, suggesting that MetS may be a risk factor affecting the prognosis of mPCA.

Development of the Home-Based Fall Prevention Knowledge (HFPK) questionnaire to assess home-based fall prevention knowledge levels among older adults in China.

BACKGROUND: Falls are one of the main reasons for mortality and morbidity in older adults. However, despite adoption of prevention strategies, the number of falls in older adults has not declined. This study aimed to develop a questionnaire to assess fall prevention knowledge and explore associated factors among Chinese community-dwelling older adults. METHODS: The Home-Based Fall Prevention Knowledge (HFPK) questionnaire was developed by Delphi expert consultation. We tested the internal consistency, reliability, and content validity of the HFPK. A total of 374 community-dwelling older adults participated in this study. The HFPK was used to assess their fall prevention knowledge. RESULTS: After being evaluated by 15 experts, the item content validity index ranged from 0.867 to 1, and the scale content validity index was 0.985, which met the criterion for content validity. Cronbach's α coefficient was 0.933, which satisfied the reliability criterion. Stepwise linear regression analysis showed that fall prevention knowledge was significantly associated with having higher education, being female, having a higher monthly income, people who were public officials before retirement, and having fewer children (p < 0.05). CONCLUSION: Fall prevention knowledge should be improved among older males and those with lower education, lower monthly income, people who were not public officials before retirement, and more children.

Healing Strategy Based on Space Adjustment for Cross-Linked Polymer Networks.

Healable materials are notable for their ability to recover from mechanical damage. Most methods for preparing cross-linked healable materials require the introduction of healing agents or supramolecular interactions in solvent environments. Hence, a strategy without the addition of functional component remains a key challenge. Herein, a healing strategy based on space adjustment is proposed with cross-linked poly(octadecyl acrylate) as a model, and this strategy demonstrates that the predesigned holes in cross-linked networks can supply the possibility for polymer coils to move and decrease the space density of the networks during the annealing process. As a result, the motilities of coils are enhanced, which allows them to easily penetrate and entangle in fracture sites. In contrast with the untreated cross-linked poly(octadecyl acrylate), which cannot heal, the space-adjusted poly(octadecyl acrylate) readily heals, and the highest healing efficiency is 96%. The ways in which the extent of space adjustment and the content of the cross-linking agent affect the healing efficiency are discussed, and the mechanism of the space adjustment strategy is studied through rheology research. This strategy concentrates on adjusting the spatial density of the network without the need for any functional design, which may be applied in various polymer systems.

The Renshen Chishao Decoction Could Ameliorate the Acute Lung Injury but Could Not Reduce the Neutrophil Extracellular Traps Formation.

The acute lung injury (ALI) causes severe pulmonary diseases, leading to a high mortality rate. The Renshen and Chishao have protective and anti-inflammatory effects against the ALI. To explore the protective effects of the Renshen Chishao (RC) decoction against the ALI, we established the lipopolysaccharide-indued ALI model and randomly divided the mice into seven groups: control group, ALI group, high-dose RC group, middle-dose RC group, low-dose RC group, middle-dose RC group + CXCR2 antagonist group, and ALI + CXCR2 antagonist group. We estimated the lung injury by the hematoxylin and eosin staining, the neutrophil extracellular traps (NETs) formations by the immunofluorescence colocalization and enzyme-linked immunosorbent assay (ELISA), and the CXCR2/CXCL2 pathway by the flow cytometry, ELISA, and real-time polymerase chain reaction. We conducted the high-throughput sequencing and enrichment analyses to explore the potential mechanisms. The results showed that the RC decoction pathologically ameliorated the lipopolysaccharide-induced lung injury and inflammatory response but failed to reduce the circulating and lung tissue NETs formation and the blood neutrophil percent. The high-dose RC decoction increased the plasma CXCL2 level, but the RC decoction had no effects on the neutrophilic CXCR2 levels. Under the inhibition of the CXCR2, the middle-dose RC decoction still decreased the lung injury score but as yet had unobvious influence on the NETs formation. Other potential mechanisms of the RC decoction against the ALI involved the pathways of ribosome and coronavirus disease 2019 (COVID-19); the target genes of inflammatory factors, such as Ccl17, Cxcl17, Cd163, Cxcr5, and Il31ra, and lncRNAs; and the regulations of the respiratory cilia. In conclusion, the RC decoction pathologically ameliorated the lipopolysaccharide-induced lung inflammatory injury via upregulating the CXCL2/CXCR2 pathway but could not reduce the circulating or lung tissue NETs formation.

Effects of teach-back health education (TBHE) based on WeChat mini-programs in preventing falls at home for urban older adults in China: a randomized controlled trial.

BACKGROUND: Falls are common among adults aged 60 years and older because of physiological changes. Most falls in older adults occur most often at home. Coupled with the lack of awareness and knowledge of preventing falls, the proportion of injuries and deaths among older adults due to falls is increasing yearly. Our study developed a WeChat mini-program for urban elderly to implement teach-back health education (TBHE) that a repeated cycle process of health education, assessment, and re-education in preventing falls at home. OBJECTIVES: This study aimed to evaluate the application effect of the TBHE-based WeChat mini-program on health education knowledge for fall prevention at home for urban older adults. DESIGN: A single-blinded, two-arm parallel-group, randomized controlled trial was conducted. SETTING: Three residential communities, named Hot Spring Apartment, Hualinyuan, and Dongtang Community in Gulou District, Fuzhou, China. PARTICIPANTS: Participants were older adults recruited from communities in Fuzhou from January to March 2021. METHODS: Fifty-nine participants agreed to participate and were assigned randomly to the intervention group (n = 29) or the control group receiving traditional health education (n = 30). Each participant in the intervention group received twice a week for a total of 8 weeks of health education interventions performed by the first author that she is intervenor according to specific themes. The trial statistician, recruiters, and participants were blinded to group allocation. The intervenor (first author) was blinded to the study hypotheses. To evaluate the effects of the intervention, we assessed participants' knowledge total score and scores of physiology and disease; drug application; mental, cognitive, and spiritual well-being; lifestyle; and house environment at baseline and 1-week post-intervention and compared scores between two groups. A two-way repeated-measures analysis of variance was conducted to examine the effects of time, group, and their interaction. RESULTS: There was a significant difference in knowledge of house environment (p = 0.003) between the two groups. Within groups, total and five dimensions knowledge scores had a significant difference (p < 0.001). Moreover, interaction effects were significant on drug application (p = 0.012) and mental, cognitive, and spiritual well-being (p = 0.015). CONCLUSIONS: The TBHE can improve knowledge on fall prevention at home among urban older adults. The TBHE based on the WeChat mini-program could enhance the efficiency and effectiveness of being educated among urban older adults. TRIAL REGISTRATION: Chinese Clinical Trial Register: ChiCTR2100052946 ; reg date: 06/11/2021.

Synthesis of selective PAK4 inhibitors for lung metastasis of lung cancer and melanoma cells.

The p21 activated kinase 4 (PAK4) is serine/threonine protein kinase that is critical for cancer progression. Guided by X-ray crystallography and structure-based optimization, we report a novel subseries of C-3-substituted 6-ethynyl-1H-indole derivatives that display high potential and specificity towards group II PAKs. Among these inhibitors, compound 55 exhibited excellent inhibitory activity and kinase selectivity, displayed superior anti-migratory and anti-invasive properties against the lung cancer cell line A549 and the melanoma cell line B16. Compound 55 exhibited potent in vivo antitumor metastatic efficacy, with over 80% and 90% inhibition of lung metastasis in A549 or B16-BL6 lung metastasis models, respectively. Further mechanistic studies demonstrated that compound 55 mitigated TGF-ß1-induced epithelial-mesenchymal transition (EMT).

Lathyrane and Jatrophane Diterpenoids from Euphorbia helioscopia Evaluated for Cytotoxicity against a Paclitaxel-Resistant A549 Human Lung Cancer Cell Line.

A phytochemical investigation on the aerial parts of Euphorbia helioscopia resulted in the isolation of 27 macrocyclic diterpenoids, including three previously unreported lathyrane derivatives, euphohelioscopoids A-C (1-3). Their structures were elucidated by spectroscopic data interpretation. Three jatrophanes, euphoscopin C (4), euphorbiapene D (6), and euphoheliosnoid A (5), showed cytotoxicity against a paclitaxel-resistant A549 human lung cancer cell line with IC50 values of 6.9, 7.2, and 9.5 µM, respectively, but were inactive against the parent A549 human lung cancer cell line (IC50 > 10 µM). It was found that jatrophanes with a benzoyloxy or a nicotinoyloxy substituent at C-7 showed more potent cytotoxic activity than their analogues containing acetyloxy and hydroxy groups at this position.

Reliability and Validity of the Chinese Nine-Item Basic Psychological Need Satisfaction Scale Based on Self-Determination Theory With Older Adults.

Background: Self-determination theory distinguishes three basic human psychological needs: competence, relatedness, and autonomy. The measurement of these needs in populations of older adults has been limited and inadequate. Yet, results from such an assessment are likely to be valuable in policymaking, specifically toward the goal of healthy aging. Aim: The objective of this study was to test the reliability and validity of the Chinese version of the Basic Psychological Need Satisfaction Scale (BPNS) based on self-determination theory with older adults. Methods: A total of 809 older adults were invited to participate in this study. We examined the item analysis, internal reliability, factorial validity, criterion validity, and measurement invariance across sex of a Chinese translation of the BPNS. Results: The findings demonstrated that the scale had a good factorial validity, criterion validity, and satisfactory internal reliability. All the items were qualified according to item analysis (p < 0.001). The Cronbach's α coefficient for the total scale was 0.877. The coefficients of three subscales were 0.826 (autonomy), 0.807 (competence), and 0.847 (relatedness). Exploratory factor analysis indicated three factors that explained 75.12% of the total variance. Confirmatory factor analysis showed measurement fit exceeded the recommended criteria in all the cases. Measurement invariance analysis manifested that the factor loadings, factor variances and covariances, and residuals to measurement structure were invariant across the male and female participants. Conclusion: The Chinese version of the BPNS based on self-determination theory was proven to be reliable and valid. The usability of the scale to assess the satisfaction of the basic psychological needs of older adults in China was demonstrated.

Effect of Bismuth Oxide Particles Size on the Thermal Excitation and Combustion Properties of Thermite Systems.

The influence of Bi2 O3 particles size at the sub-micron scale on the thermal excitation threshold and combustion performance of nano-thermite systems was investigated. Three formulas were designed and prepared, Al(100 nm)/Bi2 O3 (170 nm), Al(100 nm)/Bi2 O3 (370 nm) and Al(100 nm)/Bi2 O3 (740 nm). The samples were characterized and tested by SEM, XRD, and DSC techniques. Electrical ignition and combustion experiments were performed. The results showed that with the increase of the particle size of Bi2 O3 , in the case of slow linear heating, the exothermic heat decreased (1051.2 J g-1 , 527.3 J g-1 and 243.6 J g-1 ) and the thermal excitation threshold temperature increased (564.52 °C, 658.1 °C and 810.9 °C). Simultaneously, the state of the thermite reaction correspondingly changed to solid-solid, liquid-solid and liquid-liquid thermite reaction. In the case of rapid heating , the increase in particle size increased the excitation current (0.561A, 0.710A and 0.837A). During the combustion process, the thermite system with the smallest Bi2 O3 particle size showed the largest combustion rate, and that with the largest particle size had the longest combustion duration.

Physiologically increased total bilirubin is associated with reduced risk of first myocardial infarction: A meta-analysis and dose-response analysis.

AIM: Bilirubin has potential predictive and prognostic value for myocardial infarction (MI), but the clinical evidence remains controversial. We performed this meta-analysis to systematically quantify the relationships between circulating bilirubin levels and the incidence of MI and post-MI adverse events. DATA SYNTHESIS: We searched the PubMed, Cochrane Library, Embase, and Web of Science databases for ad-hoc studies, published up to October 17, 2020, recording bilirubin before MI (predictive analyses) or adverse events (prognostic analyses). Relative risks (RR) were pooled by a random-effects model. The dose-response analysis was conducted by restricted cubic splines. In patients without previous MI, increased total bilirubin (TB) reduced the risk of long-term (>3 year) first MI by 22% (95% confidence interval [CI]: 0.69-0.88, n = 4). The dose-response analysis indicated that the RR for first MI decreased by 2.7% per each 2 µmol/L increment of TB (three studies, 95% CI: 1.3%-4.1%, P < 0.001), with a cut-off value of 12.60 µmol/L for RR > 1.00. Elevated bilirubin reduced the incidence of first and recurrent MI by 36% (95% CI: 0.42-0.98, n = 7). However, after suffering MI, higher TB concentrations could not decrease the risk of recurrent MI (RR: 1.02, 95% CI: 0.67-1.55, n = 5) and increased the incidence of short-term (<1 year) post-MI major adverse cardiovascular events, all-cause mortality, and cardiovascular mortality, but not long-term (≥1 year). CONCLUSION: Higher TB levels within a physiological range reduced the incidence of long-term first MI, with a cut-off value of 12.60 µmol/L.

Effect of Canine-assisted Therapy on Family Function of Autism Spectrum Disorder / 中国康复理论与实践

Objective:To evaluate the effect of canine-assisted therapy on family function of autism spectrum disorder. Methods:The randomized controlled trials (RCT) about the effect of canine-assisted therapy on family function of autism spectrum disorder were retrieved from the Cochrane Library, PubMed, Web of Science, CNKI, CBM, VIP, and Wanfang Data from establishment to February, 2021. Brief Family Assessment Measure-III-General Scale (FAM-III-GS) was used to access the family function, and Children's Depression Inventory-Second Edition (CDI-2) and Spence Children's Anxiety Scale (SCAS) were used to access the psychological behavior. The quality of included studies was evaluated according to the method recommended by the Cochrane Collaboration and Joanna Briggs Institute Reviewers' manual. RevMan 5.4 software was used for meta-analysis. Results:Finally, four RCTs involving 190 patients were included. There were too less RCTs to do a meta-analysis. Two RCTs showed that the score of FAM-III-GS improved in the experimental group than in the control group. Conclusion:Canine-assisted therapy might improve the family function of patients with autism spectrum disorder.

PuMYB21/PuMYB54 coordinate to activate PuPLDß1 transcription during peel browning of cold-stored "Nanguo" pears.

Refrigeration is commonly used to extend the storage life of "Nanguo" pears, but fruit in long-term refrigeration is prone to peel browning, which is related to membrane lipid degradation. To determine the mechanism of membrane lipid degradation, we identified two R2R3-MYB transcription factors (TFs), PuMYB21 and PuMYB54, from "Nanguo" pears, which were notably expressed in response to cold stress and during the peel-browning process. The results from yeast one-hybrid, electrophoretic mobility shift, and transient expression assays indicated that both PuMYB21 and PuMYB54 directly bind to the promoter of PuPLDß1 (a key enzyme catalyzing the hydrolysis of membrane phospholipids) and activate its expression, which probably enhances the degradation of membrane phospholipids and eventually results in peel browning. Moreover, the overexpression of PuMYB21 and PuMYB54 can greatly activate the transcription of endogenous PuPLDß1 in both "Nanguo" pear fruits and calli, and their silencing can inhibit its transcription. Furthermore, yeast two-hybrid, bimolecular fluorescence complementation, and pull-down assays verified that PuMYB21 interacts with PuMYB54 to enhance the expression of PuPLDß1. In summary, we demonstrate that PuMYB21 and PuMYB54 may have roles in membrane lipid metabolism by directly binding to the downstream structural gene PuPLDß1 during the low temperature-induced peel browning of "Nanguo" pears.

Trimethylamine-N-oxide has prognostic value in coronary heart disease: a meta-analysis and dose-response analysis.

BACKGROUND: Previous clinical studies have suggested that trimethylamine-N-oxide (TMAO) could contribute to the development of atherosclerosis cardiovascular disease. However, the synthetic analysis in coronary heart disease (CHD) was not yet performed. We aimed to clarify the relationship between elevated plasma concentrations of TMAO and the incidence of major adverse cardiovascular events (MACE) in CHD patients. METHODS: Meta-analysis and dose-response analysis of hazard ratio data from prospective observational studies reporting on the association between TMAO plasma concentrations and the incidence of MACE in patients with CHD were conducted. RESULTS: Of the 2369 published articles identified in the search, seven papers, with data from nine cohort studies (10,301 patients), were included in the meta-analysis. Combined data showed that elevated plasma TMAO concentrations could increase 58% higher risk of MACE in patients with CHD (hazard ratios [HR]: 1.58; 95% confidence interval [CI] = 1.35-1.84, P = 0.000). For follow-up ≥ 1 year, it was associated with 62% higher risk of MACE in patients with longer-term than shorter-term (HR for follow-up ≥ 4 years: 1.96; 95% CI = 1.52-2.52 vs one to 3 years: 1.34; 95% CI = 1.26-1.43, P = 0.004). The dose-response analysis revealed a 'J' shaped association between TMAO concentration and the incidence of MACE (P = 0.033), with the concentration above 5.1 µmol/L being associated with HR of > 1. CONCLUSIONS: Elevated levels of TMAO are associated with an increased incidence of MACE in patients with CHD. TMAO concentration of 5.1 µmol/L may be a cut-off value for prognosis.

The characteristics of combustion reactions involving thermite under different shell materials.

To study the influence of tubular shell materials on the combustion of thermite, numerical simulations and experimental comparisons of the combustion efficiencies of thermite with PVC and stainless-steel shell materials were carried out. The thermal conductivity coefficient and heat radiation correlation coefficient of a shell material directly affect heat transfer during a heat-transfer process, that is, the lower the thermal conductivity and the higher the heat radiation reflectance coefficient, the lower the heat flux through the material and the less heat is lost. The experimental results show that compared with the stainless-steel tube material, the temperature distribution of thermite is more concentrated and the effect of melting through a steel target plate is more apparent when PVC is used as the shell material. The simulation results show that thermite in the PVC shell can produce a higher temperature, reaching 2200 °C at the loading port and 1700 °C on the steel target plate, which is maintained for 0.9 s. However, the corresponding maximum temperatures for the stainless-steel shell are only 2000 °C and 1500 °C, not yet reaching the melting point of the steel plate. The simulation results are consistent with the experimental phenomena. This work is of great significance for improving the design of thermite shells, enhancing performance, and guiding future combustion process research.

Low-temperature stress-induced aroma loss by regulating fatty acid metabolism pathway in 'Nanguo' pear.

Low temperatures retard postharvest ripening and prolong the supply period of 'Nanguo' pears. However, quality deterioration, or more specifically, a faded aroma occurs in long-term cold-stored fruits. To understand the implicit mechanism, we analyzed the change in content of the main aroma esters and fatty acids by chromatography-mass spectrometry (GC-MS), and the expression patterns of the main genes in fatty acid metabolism pathways. The results showed that hexyl hexanoate disappeared completely and the content of five other aromas declined significantly in cold-stored fruit during the optimal taste period. The content of saturated and unsaturated fatty acids significantly increased and decreased, respectively in cold-stored fruit. fadD, fadE, fadJ, atoB, fabF, SCD, FAD2, LOX2S, LOX1_5 and HPL genes down-regulated in fatty acid metabolism during shelf life in the fruit after cold storage. In conclusion, the faded aroma of cold-stored fruit was mainly regulated by fatty acid metabolism pathway.

miRNAs play important roles in aroma weakening during the shelf life of 'Nanguo' pear after cold storage.

Cold storage is commonly employed to delay senescence in 'Nanguo' pear after harvest. However, this technique also causes fruit aroma weakening. MicroRNAs are regulators of gene expression at the post-transcriptional level that play important roles in plant development and in eliciting responses to abiotic environmental stressors. In this study, the miRNA transcript profiles of the fruit on the first day (C0, LT0) move in and out of cold storage and the optimum tasting period (COTP, LTOTP) during shelf life at room temperature and after cold storage were analyzed, respectively. 314 known miRNAs were identified in 'Nanguo' pear; 176 and 135 miRNAs were significantly differentially expressed on the C0 vs. LT0 and on the COTP vs. LTOTP, respectively. After prediction the target genes of these differentially expressed miRNAs, 9 s-lipoxygenase (LOX2S), 13 s-lipoxygenase (LOX1_5), hydroperoxide lyase (HPL), and alcohol dehydrogenase (ADH1) were found differentially expressed, which were the key genes during aroma formation. The expression pattern of these target genes and the related miRNAs were identified by RT-PCR. mdm-miR172a-h, mdm-miR159a/b, mdm-miR160a-e, mdm-miR395a-i, mdm-miR399a/b/c, mdm/ppe-miR535a/b, and mdm-miR7120a/b may negatively regulate the target genes expression. These results indicate that miRNAs may play key roles in aroma weakening in cold storage 'Nanguo' pear and provide valuable information for studying the molecular mechanisms of miRNAs in the aroma weakening of fruit due to low temperature.