Decoupling the effects of air temperature change on soil erosion in Northeast China.

Changes in the air temperature tend to indirectly affect soil erosion by influencing rainfall, vegetation growth, economic development, and agricultural activities. In this study, the partial least squares-structural equation model (PLS-SEM) was used to decouple the impacts of temperature change on soil erosion in Northeast China from 2001 to 2019, and the indirect effect of temperature change on the pathways of natural and socioeconomic factors was analyzed. The results showed that temperature increase in Northeast China caused an increase in soil erosion by increasing rainfall and promoting economic development. Under the pathway of natural factors, in spring, the promoting effect on soil erosion under the influence of temperature change on rainfall was greater than the inhibiting effect on soil erosion under by the influence of temperature change on vegetation. In summer, the opposite effect was observed. Under the pathway of natural factors, over time, the promoting effect of temperature increase on soil erosion increased by 22.7%. Under the pathway of socioeconomic factors, temperature change not only aggravated soil erosion by promoting economic development, but also indirectly increased investments in agriculture and water conservation by improving the economy, thus inhibiting soil erosion to a certain extent. Over time, the contribution of temperature change to soil erosion through socioeconomic pathway was reduced by 44.4%. When the pathway of natural factors is compared with that of socioeconomics factors, temperature change imposed a more notable effect on the change in soil erosion through the socioeconomic pathway, indicating that human activities are the driving factors with a greater effect on soil erosion. Based on this, reasonable human intervention is an important means to alleviate soil erosion aggravation caused by rising temperatures.

High Throughput Sequencing Analysis of Exosomal miRNA Expressions in Early-Onset Preeclampsia Patients.

BACKGROUND: The goal of this study was to screen for differentially expressed exosomal miRNAs in peripheral blood samples of early-onset preeclampsia and normal pregnant patients using high-throughput sequencing methods and explore their effects on the pathogenesis of preeclampsia. METHODS: Peripheral blood samples from 5 patients with early-onset preeclampsia and 5 normal pregnant women (control group) were enrolled. Then, exosomes were extracted from each sample, and the procedure was replicated three times. An Illumina HiSeq4000 sequencing platform was used to analyze exosomal miRNAs in all samples before comparison. The target genes and signaling pathway predictions and the biological function enrichments of significant and differentially expressed miRNAs were assessed using Miranda and Starbase software, as well as GO and KEGG databases. RESULTS: Compared with the control, patients in the early-onset preeclampsia group had 65 significantly and differentially expressed exosomal miRNAs in their peripheral blood samples. The results have shown that of the 65 differentially expressed miRNAs, 17, including has-miR-6855, has-miR-7151, and has-miR-6777, were up-regulated, and 48, including has-miR-1247, has-miR-29B2, and has-miR-941, were down-regulated (p < 0.05). The Miranda and TargetScanS algorithms predicted a total of 2,231 target genes from the differentially expressed miRNAs. The Go and KEGG analyses showed that the principal biological function of these target genes was the regulation of Ras protein signal transduction, histone modification, GTPase-mediated signal transduction, and transforming growth factor (TGF)-ß. Additionally, the results also showed that the major pathways involved in the regulation of these functions were the PI3K Akt, MAPK, tumor necrosis factor, and EGFR tyrosine kinase inhibition signaling pathways. CONCLUSIONS: There are significant differences in the expression profiles of exosomal miRNAs between early-onset preeclampsia patients and normal pregnant women. These differentially expressed miRNAs may not only play an important regulatory role in the occurrence of early-onset preeclampsia but also participate in its pathophysiological process through genetic regulation of a variety of biological functions and signal pathways.

Intranasal Dexmedetomidine in Elderly Patients (Aged > 65 Years) During Maxillofacial Surgery: Sedative Properties and Safety Analysis.

PURPOSE: Light sedation rather than intravenous sedation is preferred when patients have a low heart rate and blood pressure during maxillofacial surgery. Intranasal administration of dexmedetomidine is reported to be efficacious and safe in adults. However, dexmedetomidine could be unsuitable for routine clinical use in elderly patients because many of these patients take ß-blockers, which increase the cardiovascular effects of dexmedetomidine. The objectives of the study were to evaluate the sedative properties and safety of intranasal dexmedetomidine, regardless of concurrent ß-blocker treatment, in elderly patients who underwent maxillofacial surgery. METHODS: This study was a retrospective analysis of 535 patients aged > 65 years (American Society of Anesthesiologists physical status I or II) who were undergoing maxillofacial surgery. Very anxious patients and those with hypertension received intranasal 1 µg/kg dexmedetomidine through an intranasal mucosal atomization device before anesthesia (local ropivacaine). RESULTS: Intranasal administration of dexmedetomidine decreased the requirement for midazolam before surgery (18 of 252 vs 63 of 283, P < .0001), but increased the requirement for norepinephrine (102 of 252 vs 8 of 283, P < .0001) during or after the surgery. A combination of a ß-blocker and intranasal administration of dexmedetomidine reduced the hemodynamic parameters for an extended period. Intranasal administration of dexmedetomidine resulted in bradycardia and hypotension, regardless of concurrent ß-blocker treatment. CONCLUSIONS: Intranasal 1 µg/kg dexmedetomidine was associated with a high sedation score during the operation, but also with bradycardia and hypotension.

The impact of COVID-19 on the ride-sharing industry and its recovery: Causal evidence from China.

The COVID-19 pandemic has brought unprecedented disruptions to many industries, and the transportation industry is among the most disrupted ones. We seek to address, in the context of a ride-sharing platform, the response of drivers to the pandemic and the post-pandemic recovery. We collected comprehensive trip data from one of the leading ride-sharing companies in China from September 2019 to August 2020, which cover pre-, during-, and post-pandemic phases in three major Chinese cities, and investigate the causal effect of the COVID-19 pandemic on driver behavior. We find that drivers only slightly reduce their number of shifts in response to increased COVID-19 cases, likely because they have to make a living from providing ride-sharing services. Nevertheless, conditional on working, drivers exhibit strong risk aversion: As the number of new cases increases, drivers strategically adjust the scope of their search for passengers, complete fewer trips, and as a result, make lower daily earnings. Finally, our heterogeneity analyses indicate that the effects appear to vary both across drivers and over time, with generally stronger effects on drivers who are older, more experienced, more active before the pandemic, and higher-status within the firm. Our findings have strong policy implications: These drivers tend to contribute more to the focal company, and also rely more on providing ride-sharing services to make a living. Therefore, they should be prioritized in stimulus plans offered by the government or the ride-sharing company.

Spinal Anesthesia With Peripheral Nerve Block Versus General Anesthesia With Peripheral Nerve Block for Elective Foot and Ankle Surgeries: A Retrospective Single-Center Study.

Peripheral nerve blocks are the regional techniques in orthopedic surgeries to control postoperative pain and have early discharge from hospital. However, anesthesia protocols for foot and ankle surgeries of institutes do not include multimodal analgesics including peripheral nerve blocks. The objective of the study was to compare spinal anesthesia with peripheral nerve block against general anesthesia with peripheral nerve block for elective foot and ankle surgeries. Patients have treated for elective foot and ankle surgery under general anesthesia (using propofol, 0.05 mg/kg dezocine, and 1% sevoflurane; GA cohort, n = 112) or spinal anesthesia (using 0.5% bupivacaine, propofol, and 0.05 mg/kg dezocine; SA cohort, n = 132) or patients have treated for elective for foot and ankle surgery under general anesthesia (GL cohort, n = 115) or spinal anesthesia (SL cohort, n = 160) with the use of peripheral nerve block (the sciatic nerve blocks and adductor canal nerve blocks using 0.25% bupivacaine and 0.1 mg/kg dexamethasone). Propofol was administered in fewer amounts if anesthesia was used with the peripheral nerve block. Patients of the GL cohort were transferred to ward 36 minutes (mean) earlier than those of the SL cohort. None of the patients of the GL and the SL cohorts have received intraoperative opioid(s) for the management of pain. Patients of the GL and the SL cohorts have reported postoperative falls within 1 day after surgeries during movement. Patients of the SL cohort experienced more frequently difficulty with sleeping. Patients of the GL and the GA cohorts have reported nausea and vomiting. Only patients of the GL cohort were required usage of vasoactive drugs. The study provides information to anesthesiologists and surgeons regarding anesthesia techniques for elective foot and ankle surgeries for better surgical outcomes (Technical Efficacy Stage: 4).

Highly sensitive electrochemical BPA sensor based on titanium nitride-reduced graphene oxide composite and core-shell molecular imprinting particles.

A sensitive electrochemical sensor was proposed via combining molecular imprinting technique with the graphene material-doped titanium nitride. The novel graphene with 3-dimensional structure displayed more binding sites and better electrochemical properties. Moreover, this study focused on coating pyrrole with electrical conductivity on the surface of silica as a monomer, and BPA as the template. The interaction made specific detection possible, between monomer and template. With a series of characterizations and electrochemical measurements, CPE (carbon paste electrode)-contained TiN-rGO composite was proved to have conductivity improved. Also, the modified polymer performed well selectivity which reflected in that it was almost impervious to distractions. Under optimized conditions, a linear dependence was observed from 0.5 to 100 nmol L-1 with a detection limit of 0.19 nmol L-1. The sensor explicated outstanding repeatability via repetitive experiment with the RSD of 0.02%, while the results of stability experiment reached the RSD of 1.90%. Eventually, it was used to analyze BPA residues in 3 kinds of daily supplies. The results indicated the potential of the sensor in environmental detection prospectively.

Misdiagnosis of a twin pregnancy with double-corner uterine rupture following salpingectomy and protrusion of the amniotic sac as an adnexal cyst: a case report.

BACKGROUND: Salpingectomy-associated uterine rupture during intrauterine pregnancy is rare in the clinic. We report a case of pregnancy with bilateral rupture of the uterine horns after bilateral salpingectomy. CASE PRESENTATION: A 30-year-old woman of Han ethnicity presented with right epigastric pain at 28 weeks and 6 days of gestation. Examination by colour Doppler ultrasound showed the following: "Twin live births with normal foetal umbilical artery blood flow indexes and a 183 mm × 112 mm anechoic zone in the right front of the uterus". Initially, we made an incorrect judgement wherein we considered the amniotic sac that was protruding into the abdominal cavity to be an adnexal cyst. Fortunately, the diagnosis of uterine rupture was confirmed before the protruded amniotic sac broke. The mother did not bleed much, and the twin foetuses survived in our case. CONCLUSION: A previous history of salpingectomy via laparoscopy could be a risk factor for uterine rupture in pregnant women. Attention should be paid to rare complications of pregnancy. To avoid adverse events, we should pay special attention to women with a history of laparoscopic salpingectomy who complain about abdominal discomfort and offer them a relevant ultrasound examination.

Photo-stimulated "turn-on/off" molecularly imprinted polymers based on magnetic mesoporous silicon surface for efficient detection of sulfamerazine.

In this study, novel photo-stimulated molecularly imprinted polymers based on magnetic mesoporous carrier surface were developed for selective identification and intelligent separation of sulfamerazine in complex samples. The photosensitive monomer of the molecularly imprinted polymers was azobenzene derivative 5-[(4-(methacryloyloxy)phenyl) diazenyl] isophthalic acid with stimulus reaction mechanisms, which has photoisomerization between trans and cis for N=N bonds. Further, the properties of the photo-stimulated molecularly imprinted polymers were further evaluated through several sets of adsorption experiments. It illustrated that the maximum adsorption amount is 0.45 mmol/L. By ultraviolet spectrophotometry, the material reaches typical characteristic peaks of photo sensitivity, and the cycle time is 16 min. Three adsorption and desorption processes were repeated, the adsorption rate reached 34.4%. Overall, the photo-stimulated molecularly imprinted polymers can enrich and separate determine sulfamerazine with high selectivity, which have good recovery for real samples.

A sensitive electrochemical sensor modified with multi-walled carbon nanotubes doped molecularly imprinted silica nanospheres for detecting chlorpyrifos.

A highly sensitive and convenient electrochemical sensor, based on surface molecularly imprinted polymers and multiwalled carbon nanotubes, was successfully developed to detect chlorpyrifos in real samples. In order to solve the problems like uneven shapes, poor size accessibility, and low imprinting capacity, the layer of the molecularly imprinted polymer was prepared on the surface of silica nanospheres. Moreover, the doping of multiwalled carbon nanotubes greatly improved the electrical properties of developed sensor. Under the optimal conductions, the electrochemical response of the sensor is linearly proportional to the concentration of chlorpyrifos in the range of 5.0 × 10-12 -5.0 × 10-8  mol/L with a low detection limit of 8.1 × 10-13  mol/L. The prepared sensor exhibited multiple advantages such as low cost, simple preparation, convenient use, excellent selectivity, and good reproducibility. Finally, the prepared sensor was successfully used to detect chlorpyrifos in vegetable and fruit.

Relationship between meaning in life and death anxiety in the elderly: self-esteem as a mediator.

BACKGROUND: Death anxiety is a common phenomenon in all societies. Older adults may be more prone to death anxiety than their younger counterparts; however, death anxiety among older adults is not well understood. This study explores the relationship between meaning in life, self-esteem, and death anxiety in senior citizens in China. METHODS: A total of 283 older adults participated in this study; data were collected via the Meaning in Life Questionnaire, the Rosenberg Self-Esteem Scale, and the Death Anxiety Scale. RESULTS: Results show that the dimensions of meaning in life, presence of meaning (r = - 0.43, p < 0.01), search for meaning (r = - 0.31, p < 0.01), and self-esteem (r = - 0.54, p < 0.01) were each negatively correlated with death anxiety. Regression analysis reveals that meaning in life significantly predicted self-esteem and death anxiety (F = 45.70, p < 0.01; R2 = 0.33). Path analysis indicated that self-esteem either completely or partially mediated the effects of meaning in life on death anxiety in older adults. CONCLUSIONS: Overall, meaning in life appears to be significantly correlated with death anxiety in older adults, and self-esteem can mediate this effect.

Ratiometric fluorescence nanosensors based on core-shell structured carbon/CdTe quantum dots and surface molecularly imprinted polymers for the detection of sulfadiazine.

Sulfadiazine is an environmental pollutant derived from abuse of antibiotics. Its content in environmental water is closely related to human health. Thus, a novel dual-emission surface molecularly imprinted nanosensor is designed for the specific adsorption and detection of sulfadiazine. In the system, blue emissive carbon quantum dots wrapped with silica served as the internal reference signal for eliminating background interference, while red emissive thioglycolic acid modified CdTe quantum dots (CdTe QDs), which are low dimensional semiconductor materials by the combination of cadmium and tellurium with excellent optical properties, were encapsulated in the imprinted layer to offer recognition signal. The fluorescence of CdTe quantum dots was quenched and the fluorescence quenching degree of carbon quantum dots was inconspicuous with the increase of concentration of sulfadiazine, thereby reflecting the color change. The detection of sulfadiazine was successfully achieved in a concentration range of 0.25-20 µmol/L with detection limit of 0.042 µmol/L and nanosensors had specific recognition for sulfadiazine over its analogues. Compared to single-emission fluorescence sensors, ratiometric fluorescence nanosensors had wider linear range and higher detection accuracy. Furthermore, the nanosensors were also successfully applied for the determination of sulfadiazine in real water and milk samples with acceptable recoveries. The study provides a feasible method for the detection of sulfadiazine and a reference for the detection of sulfonamides.

Transformation of the education of health professionals in China: progress and challenges.

In this Review we examine the progress and challenges of China's ambitious 1998 reform of the world's largest health professional educational system. The reforms merged training institutions into universities and greatly expanded enrolment of health professionals. Positive achievements include an increase in the number of graduates to address human resources shortages, acceleration of production of diploma nurses to correct skill-mix imbalance, and priority for general practitioner training, especially of rural primary care workers. These developments have been accompanied by concerns: rapid expansion of the number of students without commensurate faculty strengthening, worries about dilution effect on quality, outdated curricular content, and ethical professionalism challenged by narrow technical training and growing admissions of students who did not express medicine as their first career choice. In this Review we underscore the importance of rebalance of the roles of health sciences institutions and government in educational policies and implementation. The imperative for reform is shown by a looming crisis of violence against health workers hypothesised as a result of many factors including deficient educational preparation and harmful profit-driven clinical practices.

The priority of industrial sector coverage in China's national emission trading system: an application of the LASSO model.

This paper estimates the influences of different industries on the carbon prices and selects the industries with high market power in the carbon market. To realize price discovery in the carbon market and improve the market efficiency, we suggest that industries with higher market power should be included in the market prior to other industries. Using the LASSO regression to analyze the data from the pilot markets of China's ETS and related industrial product outputs, we find that among all related industries, the petrochemical and chemical industries affect the carbon price the most and hence should be included in China's ETS with priority. The power generation industry, though regarded as the major entity of emission control, imposes weaker influences on the carbon price. Industries that may be incorporated in China's ETS later include the transportation equipment manufacturing and the mining and metal industries.

Bolus administration of remimazolam was superior to midazolam for deep sedation in elderly patients undergoing diagnostic bronchoscopy: A randomized, double-blind, controlled trial.

BACKGROUND: To date, there is no standardized practice for the use of pharmacological sedatives during flexible bronchoscopy, particularly for elderly patients. This exploratory study aimed to assess the efficacy and safety of remimazolam at a single induced dose for deep sedation in elderly patients undergoing diagnostic flexible bronchoscopy (DFB), and compare with midazolam, a commonly used sedative. METHODS: A total of 100 elderly patients (age range 65-80 yr; American Society of Anesthesiologists Physical Status I-III) undergoing DFB were randomly allocated into 2 groups according to the sedatives used for induction: the remimazolam group and the midazolam group. Sedation induction was initiated by an intravenous bolus of remimazolam (0.135 mg/kg) or midazolam (0.045 mg/kg), respectively, both groups were combined with a high-dose of alfentanil (18 µg/kg), and supplemented with high-flow nasal cannula (HFNC) oxygen supply at a flow rate of 45 L/min. If the target depth of sedation was not achieved, propofol would be titrated as a rescue. The primary outcome was the success rate of sedation at a single induced dose to achieve target depth (Ramsay sedation score [RSS] = 4) during induction, intraoperative changes in vital signs, postoperative follow-up situation and incidence of post-bronchoscopy adverse events were evaluated as secondary outcomes. RESULTS: The success rate of sedation in the remimazolam group was significantly higher than that in the midazolam group (65.2% vs 39.6%, P = .013), while the incidence of extra sleep within 6 hours after procedure was lower in the remimazolam group as compared to the midazolam group (10.9% vs 31.3%, P = .016). No statistically significant differences were observed between the 2 groups regarding hemodynamic fluctuations, incidence of hypoxemia, and cough response during the procedure, as well as postoperative recall, willingness to undergo reexamination, and other post-bronchoscopy adverse events. CONCLUSIONS: Bolus administration of remimazolam offers advantages over midazolam for deep sedation in elderly patients undergoing DFB, in terms of a higher success rate of sedation and a lower incidence of extra sleep within 6 hours after procedure, though the safety profiles of both groups were favorable.

3D Printed Conductive Hydrogel Patch Incorporated with MSC@GO for Efficient Myocardial Infarction Repair.

Myocardial infarction (MI) results in an impaired heart function. Conductive hydrogel patch-based therapy has been considered as a promising strategy for cardiac repair after MI. In our study, we fabricated a three-dimensional (3D) printed conductive hydrogel patch made of fibrinogen scaffolds and mesenchymal stem cells (MSCs) combined with graphene oxide (GO) flakes (MSC@GO), capitalizing on GO's excellent mechanical property and electrical conductivity. The MSC@GO hydrogel patch can be attached to the epicardium via adhesion to provide strong electrical integration with infarcted hearts, as well as mechanical and regeneration support for the infarcted area, thereby up-regulating the expression of connexin 43 (Cx43) and resulting in effective MI repair in vivo. In addition, MI also triggers apoptosis and damage of cardiomyocytes (CMs), hindering the normal repair of the infarcted heart. GO flakes exhibit a protective effect against the apoptosis of implanted MSCs. In the mouse model of MI, MSC@GO hydrogel patch implantation supported cardiac repair by reducing cell apoptosis, promoting gap connexin protein Cx43 expression, and then boosting cardiac function. Together, this study demonstrated that the conductive hydrogel patch has versatile conductivity and mechanical support function and could therefore be a promising candidate for heart repair.

Gas embolism during surgical hysteroscopy leading to cardiac arrest and refractory hypokalemia: A case report and review of literature.

RATIONALE: One of the catastrophic complications of surgical hysteroscopy is venous gas embolism (VGE), and this event could cause morbidity and in serious cases may even lead to death. However, in cases of VGE accompanied by refractory hypokalemia is rare and can significantly increase the difficulty of treatment and resuscitation. Here, we successfully treated a patient with fatal VGE during surgical hysteroscopy, accompanied by difficult resuscitation with refractory hypokalemia. PATIENT CONCERNS: We report a rare case of sudden cardiac arrest due to VGE during surgical hysteroscopy, followed by difficult resuscitation with refractory hypokalemia. DIAGNOSIS: VGE was diagnosed by a sudden decrease in EtCO2, a loud mill wheel murmur in the thoracic area, and a small number of air bubbles evacuated from the internal jugular catheter. And refractory hypokalemia was diagnosed by serum potassium levels dropping frequently to as low as 2.0 mmol/L within 36 hours of resuscitation after cardiac arrest. INTERVENTIONS: Our vigilant anesthesiologist noticed the early sign of VGE with a sudden drop in EtCO2, and as the cardiac arrest occurred, interventional maneuvers were implemented quickly including termination of the surgical procedure, adjustment of the patient's position, cardiac resuscitation, continuous chest compression, and correction of electrolyte disturbances, particularly refractory hypokalemia during the early stage of resuscitation. OUTCOMES: The patient regained consciousness 4 days after the cardiac arrest and was discharged 1 month later without any neurological deficits. LESSONS: As a relatively simple procedure, surgical hysteroscopy may have catastrophic complications. This case demonstrates the full course of fatal gas embolism and difficult resuscitation during hysteroscopic surgery, and emphasizes the importance of early detection, prompt intervention, and timely correction of electrolyte disturbances, such as refractory hypokalemia.

Advances in the prevention and treatment of postoperative delirium by acupuncture: A review.

Postoperative delirium is a common postoperative complication of neurocognitive dysfunction, especially in elderly surgical patients. Postoperative delirium not only damages patients' recovery but also increases social costs. Therefore, its prevention and treatment has essential clinical and social significance. However, due to its intricate pathogenesis and limited pharmacological interventions, the effective prevention and treatment of postoperative delirium remains a thorny problem. As traditional acupuncture therapy has been shown to be an effective treatment in many neurological disorders, and in recent years, it has begun to be clinically used as an intervention for postoperative delirium. Although most clinical and animal studies confirm that multiple types of acupuncture interventions can alleviate or prevent postoperative delirium by relieving acute postoperative pain, reducing the consumption of anesthetics and analgesics, attenuating neuroinflammation and neuronal lesions, while more evidence-based medical evidence and clinical validation are needed for these encouraging effects.

Effect of Glucose Contents on Electrochemical Corrosion Behavior of Ti/ZrO2 Brazing Joint in SBF.

The effect of glucose content on the electrochemical corrosion behavior of the Ti/ZrO2 brazing joint in simulated body fluid (SBF) was researched by the means of SEM morphologies, electrochemical and XPS analyses. Herein, pitting is observed to be a dominating corrosion model under the investigated glucose content. The pitting corrosion of the joint in 200 mg/dL SBF is minimal. In addition, the joint in 200 mg/dL SBF manifests the best corrosion resistance by electrochemical analyses, which indicates that glucose content has a bidirectional effect on corrosion of the Ti/ZrO2 brazing joint. Additionally, the corrosion current value and impedance of titanium and brazing joint are close, which indicates that their corrosion resistance is similar. Finally, the OH-, Cl-, Sn2+/Sn4+ and -COOH on the joint surface are found by XPS analysis, and the mechanism of Ti/ZrO2 brazing joint corrosion is elucidated. The study provides a novel understanding of the corrosion behavior and relevant corrosion mechanism of the Ti/ZrO2 brazing joint in body fluids with different glucose content.

The Heimlich maneuver and chest compression relieve mask ventilation difficulties caused by asymptomatic laryngeal mass: A case report and review of literature.

RATIONALE: Some laryngeal masses are typically asymptomatic and easily ignored. However, they can be rare causes of unanticipated difficult airway, leading to critical situations such as "cannot ventilate" or "cannot ventilate and cannot intubate" during anesthesia induction. Inappropriate airway management in such scenarios can have catastrophic consequences for an anesthetized patient. Here we report a case of sudden, unanticipated difficult mask ventilation caused by an asymptomatic supraglottic mass during sedative induction, which was quickly and effectively relieved by the Heimlich maneuver and chest compression. PATIENT CONCERNS: We report a rare case of airway crisis occurred during sedative induction in a 63-year-old patient scheduled for a routine flexible bronchoscopy, and no evidence of respiratory difficulty or signs of obstruction was found in preoperative evaluation. DIAGNOSES: A detailed examination of laryngopharyngeal structure under bronchoscopy revealed a supraglottic soft-tissue mass with a size of 1.6 × 0.8 cm covering the membranous part of the glottic area, which was the true cause of difficult mask ventilation in this patient during sedative induction. INTERVENTIONS: As the unanticipated difficult mask ventilation occurred, 2-handed mask ventilation was initiated immediately for 9 attempts but failed. Fortunately, the airway crisis was successfully relieved with 2 Heimlich attempts and 3 chest compressions, and no need for a laryngeal mask airway. OUTCOMES: Once the airway crisis was relieved and the supraglottic mass was confirmed, the patient underwent a second sedative anesthesia and a successful laryngeal mask airway-assisted bronchoscopy, with no post-bronchoscopy adverse events. LESSONS: Asymptomatic supraglottic masses can cause valve-like upper airway obstruction and lead to unanticipated difficult mask ventilation. The Heimlich maneuver and chest compression may be effective in such critical situations and can serve as an emergency intervention.

Effects of Mn content on austenite stability and mechanical properties of low Ni alumina-forming austenitic heat-resistant steel: a first-principles study.

Low Ni alumina-forming austenitic (AFA) heat-resistant steel is an advanced high-temperature stainless steel with reduced cost, good machinability, high-temperature creep strength, and high-temperature corrosion resistance. Using the First-principles approach, this study examined the effect of Mn content on austenite stability and mechanical properties at the atomic level. Adding Mn to low Ni-AFA steel increases the unit cell volume with an accompanying increase in the absolute value of formation energy; the austenite formed more easily. The austenitic matrix binding energy decreases and remains negative, indicating austenite stability. As the Mn content increases from 3.2 to 12.8 wt%, the system's bulk modulus (B) rises significantly, and the shear modulus (G) falls. In addition, the system's strength and hardness decrease, and the Poisson ratio of the austenite matrix increases with improved elasticity; the system has excellent plasticity with an increase in the B/G. For the Fe22-Cr5-Ni3-Al2 system, with the increase of Mn content, the electron density distribution between the atoms is relatively uniform, and the electrons around the Mn atoms are slightly sparse, which will slightly reduce the structural stability of the matrix. The experiment demonstrated the matrix maintains the austenitic structure when adding 3.2-12.8 wt% Mn elements to low Ni-AFA steel. At an Mn content of 8 wt%, the overall mechanical properties of the high-Mn AFA steel are optimal, with a tensile strength of 581.64 MPa, a hardness of 186.17 HV, and an elongation of 39%.