[Clinical value of routine contrast esophagram in the diagnosis of anastomotic leakage for three-incision esophagectomy with cervical anastomosis].

Objective: To examine the clinical value of routine contrast esophagram (RCE) for the diagnosis of anastomotic leakage (AL) after three-incision esophagectomy with cervical anastomosis. Methods: Clinical data of 1 022 patients with esophageal cancer who underwent McKeown three-incision esophagectomy with cervical anastomosis from January 2015 to December 2019 at Department of Minimally Invasive Esophageal Surgery, Tianjin Medical University Cancer Hospital and Institute were analyzed retrospectively. There were 876 males and 146 females, aging(M(IQR)) 48(16) years (range: 36 to 84 years). There were 253 patients (24.8%) with neoadjuvant therapy, and 817 patients (79.9%) with minimally invasive esophagectomy. According to the diagnosis and treatment habits of the attending surgeons, 333 patients were included in the RCE group, and RCE was performed on the 7th day postoperative, while 689 patients were included in the non-RCE group, and RCE was performed when the patients had suspicious symptoms. Taking clinical symptoms, RCE, CT, endoscopy and other methods as reference to the diagnosis of AL, the sensitivity and specificity were used to analyze and evaluate the efficacy of RCE for the diagnosis of AL. The data were compared by U test or χ² test between groups. Results: The incidence rate of AL after three-incision esophagectomy was 7.34% (75/1 022), including 30 cases in the RCE group and 45 cases in the non-RCE group (9.0%(30/333) vs. 6.5%(45/689), χ²=2.027, P=0.155). The diagnostic time of AL was 9(5) days postoperative (range: 4 to 30 days). Among them, 23 cases showed cervical leakages, 50 cases showed intro-thoracic leakages, and 2 cases both cervical and intro-thoracic leakages. The diagnostic time of patients with intro-thoracic leakages was longer than that of cervical leakages (10(4) days vs. 6(3) days, Z=-2.517, P=0.012). Among the 333 patients in the RCE group, 16 cases of RCE indicated leakages including 11 cases of true positive and 5 cases determined to be false positive, while 317 cases indicated no abnormalities including 19 cases developed leakages. The sensitivity and specificity of RCE to detect AL were 36.7%(11/30) and 98.3%(298/333), respectively. The Youden-index was 0.35, and the diagnostic accuracy was 92.8%(309/333). The positive and negative predictive value were 11/16 and 94.0%(298/317), respectively. Conclusions: Routine contrast esophagram after three-incision esophagectomy with cervical anastomosis has low sensitivity and high specificity in the diagnosis of AL. The diagnostic time of AL is the 9th day after surgery. It is necessary to prolong the observation time clinically, and combine RCE with CT, endoscopy and other inspection methods for diagnosis.

[Progress in health effects and measurement standards of ultraviolet radiation in the workplace].

Ultraviolet radiation affects human health. On the one hand, moderate amounts of UV radiation can promote human health and have the effect of promoting vitamin D production; but on the other hand, excessive UV radiation can also cause adverse effects on human skin and eyes, such as causing skin photoaging, skin cancer, electrophthalmia and cataracts to occur. Therefore, the measurement of ultraviolet radiation is extremely important. This paper mainly reviews the health effects of ultraviolet radiation and the progress of measurement standards in the workplace, and puts forward suggestions on the revision of the existing standards from five aspects including use new measuring instruments and methods, improve the existing measuring instruments, specify the number of measurements, expand the scope of application of the standards and consider the influence of the sun on the measurement of artificial ultraviolet radiation, so as to provide reference for the revision of new standards.

[Descemet membrane endothelial keratoplasty in initial cases: analysis and management of surgical complications].

Objective: To investigate causes and management of surgical complications of Descemet membrane endothelial keratoplasty (DMEK) in initial cases. Methods: A retrospective study. A total of 52 eyes of 52 patients underwent DMEK by one surgeon in Peking University Third Hospital from February 2017 to December 2019, including 17 males and 35 females, aged (66±12) years. All patients' demographic characteristics, previous surgical history, intraoperative and postoperative complications were recorded. Results: Intraoperative complications included difficulties in unfolding the graft in 6 cases (11.5%), inverted grafts in 5 cases (9.6%), grafts rushing out of the anterior chamber in 2 cases (3.8%), grafts injected behind the iris in 3 cases (5.8%) and hemorrhage in 1 case. Partial graft detachment that occurred in 28 cases (53.8%) was the most frequent postoperative complication. Rebubbling was performed in 25 cases (48.1%). Pupillary block occurred in 9 cases (17.3%) and was managed by reducing air under a slit lamp. Primary graft failure occurred in 3 cases (5.8%) and viral infection occurred in 2 cases (3.8%). Conclusions: The rate of complications of DMEK in initial cases is higher than that of Descemet stripping automated endothelial keratoplasty. Intraoperative graft inversion and postoperative graft detachment are the most common complications. It is important to select appropriate indications and discover or manage intraoperative and postoperative complications in time to reduce the incidence of complications. (Chin J Ophthalmol, 2021, 57:595-600).

[Occurrence pattern of musculoskeletal disorders and its influencing factors among manufacturing workers].

OBJECTIVE: To explore the occurrence pattern and its influencing factors of multi-site work-related musculoskeletal disorders (WMSDs) of the main affected body sites among manufacturing workers. METHODS: Musculoskeletal disorders questionnaire was adopted to investigate the prevalence of WMSDs and the influencing factors among workers from four manufacturing factories in China. The case of WMSDs was defined as the one who had symptoms such as pain, numbness, discomfort, or limitation of activities in one or more of the nine body sites, including neck, shoulder, elbow, wrist/hand, upper back, lower back, hip/thigh, knee and ankle/foot during the last year, which lasted for more than 24 hours and did not completely relieve after rest. Besides, trauma, disability, other acute injuries or sequelae were excluded. The correlation of WMSDs between different body sites was estimated by the prevalence ratio (PR) calculated by log-binominal model. The influencing factors of multi-site WMSDs of the main affected body sites were analyzed by multinomial logistic regression model. RESULTS: The overall prevalence rate of WMSDs was 79.7% among the manufacturing workers. The main affected body sites were lower back, neck, shoulder and upper back, of which the prevalence rates were 62.3%, 55.7%, 45.6%, and 38.7%, respectively. The PR values of WMSDs among these sites were relatively high. The prevalence of multi-site WMSDs involving these four sites at the same time was 25.2%, and that of three to four sites was 41.4%. Multinomial Logistic regression analysis suggested that influencing factors of multi-site WMSDs in 3-4 sites of neck, shoulder, upper back and lower back involved several aspects. Among these factors, females (OR=2.86, 95%CI 2.38-3.33) and individuals with job tenure of 15-19 years (OR=1.87, 95%CI 1.49-2.34) might have higher risk of disease. Biomechanical factors, such as often bending neck forward or holding neck in a forward position for long periods (OR=2.15, 95%CI 1.86-2.48), often twisting neck or holding neck in a twisted position for long periods (OR=1.64, 95%CI 1.40-1.92) and often twisting trunk heavily (OR=1.40, 95%CI 1.20-1.64) might be risk factors. In the aspect of work organization, doing the same work every day (OR=1.73, 95%CI 1.44-2.08), shortage of workers (OR=1.50, 95%CI 1.31-1.71) and often working overtime (OR=1.38, 95%CI 1.20-1.60) might increase the risk of disease. Factors, such as often standing for long periods at work (OR=0.77, 95%CI 0.65-0.91) and feeling breaks sufficient (OR=0.51, 95%CI 0.44-0.59) were suggested to be protective factors with OR<1. CONCLUSION: The pre-valence rates of WMSDs in neck, shoulder, upper back, and lower back were high among manufacturing workers in this study. The correlation of WMSDs of these four sites was close in this study, and the comorbidity rate of 3-4 sites of these sites was relatively high, suggesting that there might be a multi-site occurrence pattern of WMSDs in "neck-shoulder-upper back-lower back" among manufacturing workers. The main influencing factors of this pattern included individual factors, biomechanical factors and work organization factors.

[Prognosis analysis of primary breast diffuse large B cell lymphoma].

Objective: To investigate the clinical characteristics, therapy modality and prognosis of primary breast diffuse large B-cell lymphoma(PB-DLBCL). Methods: A total of 68 patients with PB-DLBCL treated in Tianjin Medical University Cancer Institute and Hospital were enrolled between January 1, 2004 and January 31, 2017. Clinicopathological data were retrospectively analyzed. 67 patients were female and only one male. The median age was 56 years old. 46 patients had Ann Arbor clinical stageⅠ~Ⅱ disease, and the other 22 were stage Ⅲ~Ⅳ. The patients with and without B symptom were 11 and 57, respectively. Kaplan-Meier method was used for univariate analysis to calculate the 5-year overall survival (OS) rate and 5-year progress-free survival (PFS) rate, compared using the log rank test. Cox regression analysis was used for multivariate analysis. Results: The 1, 3, 5-year OS rate were 84.0%, 78.0% and 73.0%, and 1, 3, 5-year PFS rate were 80.0%, 71.0% and 51.0%, respectively. Univariate analysis indicated that eastern cooperative oncology group (ECOG) score, Ann Arbor clinical stage, international prognostic index (IPI) score, risk stratification, B symptom, ß2-microglobulin(ß2-MG) level, size of the tumor and cycles of chemotherapy were prognostic factors for OS (all P<0.05), and Ann Arbor clinical stage, IPI score, risk stratification and B symptom were prognostic factors for PFS (all P<0.05). Multivariate analysis indicated that Ann Arbor clinical stage was independent prognostic factor for OS(P=0.029) and B symptom was independent prognostic factor for PFS(P=0.028). Conclusions: Prognosis of PB-DLBCL was relatively good. Ann Arbor clinical stage and B symptom were independent prognostic factors for OS and PFS, respectively.

[Application of U-shaped convolutional neural network in auto segmentation and reconstruction of 3D prostate model in laparoscopic prostatectomy navigation].

OBJECTIVE: To investigate the efficacy of intraoperative cognitive navigation on laparoscopic radical prostatectomy using 3D prostatic models created by U-shaped convolutional neural network (U-net) and reconstructed through Medical Image Interaction Tool Kit (MITK) platform. METHODS: A total of 5 000 pieces of prostate cancer magnetic resonance (MR) imaging discovery sets with manual annotations were used to train a modified U-net, and a set of clinically demand-oriented, stable and efficient full convolutional neural network algorithm was constructed. The MR images were cropped and segmented automatically by using modified U-net, and the segmentation data were automatically reconstructed using MITK platform according to our own protocols. The modeling data were output as STL format, and the prostate models were simultaneously displayed on an android tablet during the operation to help achieving cognitive navigation. RESULTS: Based on original U-net architecture, we established a modified U-net from a 201-case MR imaging training set. The network performance was tested and compared with human segmentations and other segmentation networks by using one certain testing data set. Auto segmentation of multi-structures (such as prostate, prostate tumors, seminal vesicles, rectus, neurovascular bundles and dorsal venous complex) were successfully achieved. Secondary automatic 3D reconstruction had been carried out through MITK platform. During the surgery, 3D models of prostatic area were simultaneously displayed on an android tablet, and the cognitive navigation was successfully achieved. Intra-operation organ visualization demonstrated the structural relationships among the key structures in great detail and the degree of tumor invasion was visualized directly. CONCLUSION: The modified U-net was able to achieve automatic segmentations of important structures of prostate area. Secondary 3D model reconstruction and demonstration could provide intraoperative visualization of vital structures of prostate area, which could help achieve cognitive fusion navigation for surgeons. The application of these techniques could finally reduce positive surgical margin rates, and may improve the efficacy and oncological outcomes of laparoscopic prostatectomy.

[Analysis of characteristics and influencing factors of fine particulate matters and submicron particulate matters in printing shop].

Objective: To analyze the physical characteristics of fine particulate matters (PM(2.5)) and submicron particulate matters (PM(1)), and investigate the factors influencing the emission peak of printer particles. Methods: A 12-hour particle concentration monitoring for PM(2.5) and PM(1) was conducted in a printing shop on January 5(th), 2018. PM(2.5) in the air was analyzed after the monitoring process to figure out morphological characteristics and element composition of printer particles. Besides, experiments were carried out in an enclosed space to detect the number concentration peaks of PM(1) during every printing process. Influencing factors investigated in this study were printer types, toner coverages and interval time between different printing processes. Results: The 12-hour particles concentration monitoring showed that the number concentration of PM(1) and the mass concentration of PM(2.5) were 7.510×10(4) pt/cm(3) and 96.85 µg/m(3). The diameter of most PM(2.5) was less than 100 nm, with a fractal dimension of 2.591. Most PM(2.5) appeared as regular spheres with typical agglomeration phenomenon, while some were in rhabditiform or irregular shapes. Element analysis showed that PM(2.5) was mainly composed of C, O, Si, Ca, with less metallic element. The PM(1) emission peak values of three printers were 3.60×10(4), 3.43×10(4), 0.31×10(4) pt/cm(3), respectively and the difference was not statistically significant (χ(2)=5.42, P>0.05). When the page coverage rate was 0%, 2.5%, 5%, 10%, 20% and 50%, the PM(1) emission peak value of printer A was 6.74×10(4), 4.62×10(4), 3.82×10(4), 2.82×10(4), 1.00×10(4) and 1.08×10(4) pt/cm(3), and the difference was also not statistically significant (χ(2)=7.01, P>0.05). The natural logarithm of PM(1) emission peak value in printing work was associated with the resting time before printing and the change value of heating roller temperature (r value was 0.83 and 0.89, respectively, all P values<0.05). Conclusion: PM(2.5) and PM(1) in the printing shop stayed at a high level. Particles appeared as various shapes and element compositions were complex. The temperature change of heating roller was one of most important factors that lead to the increased number concentration peak of PM(1).

[Application of CiteSpace software in the visualization analysis of work-related musculoskeletal disorders].

Objective: To investigate the visual application of the CiteSpace software in the field of work-related musculoskeletal disorders (WMSDs) . Methods: The literature on WMSDs research, published from 1991 to 2017, was retrieved in Web of Science database. The CiteSpace 5.2 was used to make visualization analysis on the hotspots and tendency of the keywords, authors, countries (regions) and research institutes in relevant literature. Results: A total of 3224 literatures were included in the analysis. The amount of the literatures published was increasing annually. The key word co-occurrence network showed that the research hotspots mainly focused on the study of epidemiology, risk factors, symptoms, and other aspects of WMSDs. The cooperation network and time network of counties and regions showed that America and Europe were at the leading position in the field of WMSD, and the top three were America, Canada and Sweden. The developing countries, like Brazil and China, had also begun to make relative research since 2000. In research cooperation, the collaboration among countries, research institutions was relatively close, and multiple leading core authors and teams were formed in the international arena. Conclusion: The CiteSpace software can directly demonstrate the hotspots and tendency in the area of WMSDs.

[Research on the reliability and validity of postural workload assessment method and the relation to work-related musculoskeletal disorders of workers].

OBJECTIVE: To form a new assessment method to evaluate postural workload comprehensively analyzing the dynamic and static postural workload for workers during their work process to analyze the reliability and validity, and to study the relation between workers' postural workload and work-related musculoskeletal disorders (WMSDs). METHODS: In the study, 844 workers from electronic and railway vehicle manufacturing factories were selected as subjects investigated by using the China Musculoskeletal Questionnaire (CMQ) to form the postural workload comprehensive assessment method. The Cronbach's α, cluster analysis and factor analysis were used to assess the reliability and validity of the new assessment method. Non-conditional Logistic regression was used to analyze the relation between workers' postural workload and WMSDs. RESULTS: Reliability of the assessment method for postural workload: internal consistency analysis results showed that Cronbach's α was 0.934 and the results of split-half reliability indicated that Spearman-Brown coefficient was 0.881 and the correlation coefficient between the first part and the second was 0.787. Validity of the assessment method for postural workload: the results of cluster analysis indicated that square Euclidean distance between dynamic and static postural workload assessment in the same part or work posture was the shortest. The results of factor analysis showed that 2 components were extracted and the cumulative percentage of variance achieved 65.604%. The postural workload score of the different occupational workers showed significant difference (P<0.05) by covariance analysis. The results of nonconditional Logistic regression indicated that alcohol intake (OR=2.141, 95%CI 1.337-3.428) and obesity (OR=3.408, 95%CI 1.629-7.130) were risk factors for WMSDs. The risk for WMSDs would rise as workers' postural workload rose (OR=1.035, 95%CI 1.022-1.048). There was significant different risk for WMSDs in the different groups of workers distinguished by work type, gender and age. Female workers exhibited a higher prevalence for WMSDs (OR=2.626, 95%CI 1.414-4.879) and workers between 30-40 years of age (OR=1.909, 95%CI 1.237-2.946) as compared with those under 30. CONCLUSION: This method for comprehensively assessing postural workload is reliable and effective when used in assembling workers, and there is certain relation between the postural workload and WMSDs.

Prevalence of kidney stones and associated risk factors in the Shunyi District of Beijing, China.

INTRODUCTION: Kidney stone formation is a multifactorial condition that involves interaction of environmental and genetic factors. Presence of kidney stones is strongly related to other diseases, which may result in a heavy economic and social burden. Clinical data on the prevalence and influencing factors in kidney stone disease in the north of China are scarce. In this study, we explored the prevalence of kidney stone and potentially associated risk factors in the Shunyi District of Beijing, China. METHODS: A population-based cross-sectional study was conducted from December 2011 to November 2012 in a northern area of China. Participants were interviewed in randomly selected towns. Univariate analysis of continuous and categorical variables was first performed by calculation of Spearman's correlation coefficient and Pearson Chi squared value, respectively. Variables with statistical significance were further analysed by multivariate logistic regression to explore the potential influencing factors. RESULTS: A total of 3350 participants (1091 males and 2259 females) completed the survey and the response rate was 99.67%. Among the participants, 3.61% were diagnosed with kidney stone. Univariate analysis showed that significant differences were evident in 31 variables. Blood and urine tests were performed in 100 randomly selected patients with kidney stone and 100 healthy controls. Serum creatinine, calcium, and uric acid were significantly different between the patients with kidney stone and healthy controls. Multivariate logistic regression revealed that being male (odds ratio=102.681; 95% confidence interval, 1.062-9925.797), daily intake of white spirits (6.331; 1.204-33.282), and a history of urolithiasis (1797.775; 24.228-133 396.982) were factors potentially associated with kidney stone prevalence. CONCLUSIONS: Male gender, drinking white spirits, and a history of urolithiasis are potentially associated with kidney stone formation.

[Association between variations in protocadherin 15 gene and occupational noise-induced hearing loss].

Objective: The aim of this study was to investigate whether genetic variability in the protocadherin 15 (PCDH15) gene may correspond with increased susceptibility to noise-induced hearing loss (NIHL) in a Chinese population. Methods: A nested case-control study was performed that followed a cohort of 7 445 noise-exposed workers in a steel factory of Henan province in China from January 1, 2006 to December 31, 2015. In this study, 394 cases who had an average hearing threshold of more than 40 dB (A) in high frequency were defined as the case group, and 721 controls who had an average hearing threshold of less than 35 dB (A) in high frequency and less than 25 dB (A) in speech frequency were defined as the control group. A questionnaire was completed by participants and a physical test was also conducted. SNP genotyping was performed using the SNPscanTM Kit. Multivariate unconditional logistic regression additive models were used to analyze the genotypes in different groups, and the association with NIHL. Unconditional logistic regression models were used to assess the associations between the genotypes and NIHL. Results: The average age of study participants was (40.5±8.3) years and the median number of noise-exposed working years M (P25, P75) was 21.1 (9.1, 27.3). The range of noise exposed levels and the levels of cumulative noise exposure (CNE) were 80.1- 98.8 dB(A) and 86.6- 111.2 dB(A), respectively. Only the distribution of the genotypes (TT/CC/CT) of rs11004085 in the PCDH15 gene showed a significant difference between the case and control groups (P=0.049). In the case group, the distribution was 370 (93.9%), 24 (6.1%) and 0; in the control group, the distribution was 694 (96.3%), 23 (3.2%) and 1 (0.1% ). After smoking, drinking, hypertension, height and CNE adjustment, compared with the TT genotype individuals with the CC/CT genotype had a 1.90-fold increased risk of NIHL (95% CI: 1.06- 3.40). After stratified these data by the noise exposure level or CNE when the noise exposure level was>85 dB (A), compared with cases with the AA genotype of rs10825113, individuals with the GA/GG genotype had a 2.63-fold increased risk of NIHL (95% CI: 1.12- 6.14). When the CNE was ≤ 98 dB(A), compared with cases with the TT genotype of rs11004085, individuals with the CC/CT genotype had a 2.96-fold increased risk of NIHL (95% CI: 1.33- 6.56). However, these differences were not significant after Bonferroni correction had been applied. Conclusions: The results confirmed that genetic variation within the PCDH15 gene may affect the susceptibility to NIHL.

[Association between eye absent homolog 4 gene polymorphisms and occupational noise-induced hearing loss].

Objective: To identify the association between genetic polymorphisms in the eye absent homolog 4 (EYA4) gene and noise-induced hearing loss (NIHL). Method: A nested case control study was conducted based on a cohort of noise-exposed subjects. In total, 292 cases were selected from a steel factory from 6 297 subjects during Jan 1, 2006 to Dec 12, 2015,who had an average hearing threshold of more than 40 dB(A); 584 matched control subjects for each case were designated on the basis of matched criteria including same gender, age (±5 years) and duration of exposure to noise (±2 years). What's more, the control group had an average hearing threshold of less than 35 dB(A) in high frequency and less than 25 dB(A) in speech frequency. Four single nucleotide polymorphisms (SNPs) of the EYA4 gene were genotyped using a SNPscanTM multiplex SNP genotyping kit. Hardy-Weinberg equilibrium tests were performed using a χ2 test for goodness-of-fit for each SNP among the control group, and the effects of genotypes of the EYA4 gene on NIHL were analyzed by logistic regression. The haplotypes were established and their frequencies in the two groups were assessed using Haploview 4.2 and Phase 2.1 software, and interactive effects between haplotypes and cumulative noise exposure were analyzed. Results: The average age of the subjects was (40.1±8.4) years and the average number of noise-exposed working years was 20.3 (8.4, 27.3) years. The range of noise exposure levels and the cumulative noise exposure were 80.2- 98.8 dB (A) and 86.6- 111.2 dB(A) · year, respectively. After adjustment for covariates including height, blood pressure, drinking status and smoking status, in the noise intensity>85 dB (A) group, subjects carrying the rs3813346 TT genotype had a higher NIHL risk than those carrying the GG genotype, and the adjusted OR (95% CI) value was 2.12 (1.21- 3.69). In the cumulative noise exposure>98 dB (A) · year group, compared with haplotype TGC, haplotype CGT showed a protective effect in the development of NIHL, with an adjusted OR (95% CI) value of 0.60 (0.37-0.97), however, the significance of intercation between EY4 gene of noise was lost after Bonferroni correction. Conclusion: Genetic polymorphism in the EYA4 gene may be a genetic susceptibility factor for NIHL.

[Investigation into the relationship between mitochondrial 12 S rRNA gene, tRNA gene and cytochrome oxidase â ¡ gene variations and the risk of noise-induced hearing loss].

Objective: To explore the relationship between mitochondrial 12 S rRNA gene variation, tRNA gene variation and cytochrome oxidase Ⅱ gene point mutations and the risk of noise-induced hearing loss (NIHL). Methods: A nested case-control study was performed that followed a cohort of 7 445 noise-exposed workers in a steel factory in Henan province, China, from January 1, 2006 to December 31, 2015. Subjects whose average hearing threshold was more than 40 dB(A) in high frequency were defined as the case group, and subjects whose average hearing threshold was less than 35 dB(A) in high frequency and less than 25 dB (A) in speech frequency were defined as the control group. Subjects was recruited into the case group (n=286) and the control group (n=286) according to gender, age, job category and time of exposure to noise, and a 1∶1 case-control study was carried out. We genotyped eight single nucleotide polymorphisms in the mitochondrial 12 S rRNA gene, the mitochondrial tRNA gene and the mitochondrial cytochrome oxidase Ⅱ gene using SNPscan high-throughput genotyping technology from the recruited subjects. The relationship between polymorphic sites and NIHL, adjusted for covariates, was analyzed using conditional logistic regression analysis, as were the subgroup data. Results: The average age of the recruited subjects was (40.3±8.1) years and the length of service exposure to noise was (18.6±8.9) years. The range of noise exposed levels and cumulative noise exposure (CNE) was 80.1- 93.4 dB (A) and 86.8- 107.9 dB (A) · year, respectively. For workers exposed to noise at a CNE level<98 dB (A) · year, smokers showed an increased risk of NIHL of 1.88 (1.16-3.05) compared with non-smokers; for workers exposed to noise at a CNE level ≥98 dB(A) · year, smokers showed an increased risk of NIHL of 2.53 (1.49- 4.30) compared with non-smokers. For workers exposed to noise at a CNE level<98 dB (A) · year, the results of univariate analysis and multifactor analysis, adjusted by smoking and CNE, suggested that the risk of NIHL in workers exposed to noise carrying the GG genotype (G827A) was lower than that of NIHL workers exposed to noise carrying the AA genotype (G827A) [OR (95% CI) were 0.18 (0.04- 0.82) and 0.19 (0.04- 0.88), respectively]. Conclusion: Smoking increased the risk of NIHL in the present study. For workers subjected to a CNE<98 dB(A)·year, the mitochondrial genetic variant G827A was found to be significantly associated with the risk of NIHL.

Molecular dynamics simulation of interparticle spacing and many-body effect in gold supracrystals.

Interparticle spacing in supracrystals is a crucial parameter for photoelectric applications as it dominates the transport rates between neighboring nanoparticles (NPs). Based on large-scale molecular dynamics simulations, we calculate interparticle spacing in alkylthiol-stabilized gold supracrystals as a function of the NP size, ligand length and external pressure. The repulsive many-body interactions in the supracrystals are also quantified by comparing the interparticle spacing with that between two individual NPs at equilibrium. Our results are consistent with available experiments, and are expected to help precise control of interparticle spacing in supracrystal devices.

Elastic properties of gold supracrystals: Effects of nanocrystal size, ligand length, and nanocrystallinity.

Atomistic molecular dynamics simulations are performed to study the elastic properties of alkylthiol-functionalized gold supracrystals. The predicted Young's and shear moduli are around 1 GPa and 100 MPa, respectively. We show that, with increasing NC size, the Young's modulus decreases while the shear modulus essentially remains invariant; with increasing ligand length, the Young's modulus increases but the shear modulus decreases. Moreover, significant increase in the Young's modulus is seen when the polycrystalline NCs are replaced by single-crystal ones of the same size. All these are in reasonable agreement with available experiments. We attribute the mechanisms to the interaction between capping ligands as well as its variations caused by the change in ligand length and NC geometry. The results may deepen our understanding of elastic properties of the supracrystals and their influential factors.

[Association between grainyhead-like 2 gene polymorphisms and noise-induced hearing loss].

OBJECTIVE: To investigate association between genetic polymorphism in the grainyhead-like 2 gene (GRHL2) and noise-induced hearing loss (NIHL) in the Chinese population. METHODS: A matched case-control association study was employed, In which, 3 790 workers exposed to continuous and steady-state occupational noise in a steel factory participated. The questionnaires were adopted to collect individual features and audiometry tests performed. In the sstudy, 286 subjects were diagnosed as cases, Which were each designated on the basis of the matched criterion, and 286 paired samples were selected finally. Noise intensity was measured according to the standards given in 'Measurement of Noise in the Workplace'(Occupational Health Standard of the People's Republic of China, GBZ/T189.8-2007). Cumulative noise exposure (CNE) was calculated, according to monitoring data on A-weighed sound pressure level and employment time. Genomic DNA was obtained from peripheral blood samples using 2 mL DNA extraction Kit following the manufacturer's protocol. Five single nucleotide polymorphisms (SNPs) of GRHL2 were genotyped by multiplex SNP genotyping kit. The continuous variables and categorical variables were analyzed by t-test and chi-square test respectively. Multivariate Logistic regression was used to test the association between genetic frequency and disease status, with adjustments for the possible confounding variables. The haplotypes were established and their frequencies in the two groups were assessed by haploview and phase softwares. RESULTS: All the five SNPs (rs3735713, rs3824090, rs3735714, rs3735715 and rs611419) were in Hardy-Weinberg equilibrium (HWE) (P>0.05). The subjects carrying rs3735715 GG genotype had a higher NIHL risk than those carrying the GA genotype under the co-dominant model (OR=0.644, 95% CI: 0.442-0.939, P=0.022) after adjustment for height, blood pressure, drinking status and smoking status. After being stratified by CNE, in the CNE ≥ 98 dB (A) group, rs3735715 polymorphism was associated with the NIHL under the co-dominant model (OR=0.509, 95% CI: 0.281-0.923, P=0.026) after adjustment for height, blood pressure, drinking status and smoking status as well. However, no statistical significant difference was found in variant genotypes of the other SNPs between the case and control subjects. Four-locus (rs3735713, rs3824090, rs3735714 and rs3735715) haplotypes were constructed, and no risk or protective haplotypes was identified. CONCLUSION: It is suggested that GRHL2 polymorphisms may be associated with development of NIHL.

A coarse-grained simulation for tensile behavior of 2D Au nanocrystal superlattices.

We performed a coarse-grained. molecular dynamics (MD) simulation to study the unidirectional tension of 2D superlattices of alkythiol-ligated Au nanocrystals (NCs). Consistent with available experiments, the predicted Young's modulus is in the range of 6-15 GPa, exhibiting a trend of decreasing with the increasing NCs' size and decreasing ligand length. Our simulation shows that the deformation of the superlattice experiences elastic and nonelastic stages before defect nucleation at the NC level. The larger tensile strain gives rise to slips along the most densely packed lines, making them equal to [Formula: see text] with the tensile direction before deformation, which further triggers the occurrence of cavities and cracks and finally leads to the fracture of the specimen. These results provide a clear picture for the tensile behavior of 2D superlattices from deformation to rupture.

Ultra-sensitive analysis of a cantilevered single-walled carbon nanocone-based mass detector.

The ultra-sensitivity of mass detectors using individual cantilevered single-walled carbon nanocone (SWCNC) resonators is first investigated. A higher-order gradient theory, derived at the atomic level, is applied for modeling SWCNC resonators. Numerical simulations using a mesh-free computational framework based on moving Kriging interpolation are conducted to investigate the mass sensitivity of cantilevered SWCNC resonators with extra mass loading as well as with equivalent single-walled carbon nanotube (SWCNT) resonators. Comparison of the magnitude of resonant frequency shifts, the key criterion for mass sensitivity, of these two kinds of resonators demonstrates a far higher mass sensitivity for SWCNC resonators than for SWCNT resonators, thus suggesting a new method for ultra-sensitive mass detection via SWCNC resonators. The dependence of the mass sensitivity of SWCNC resonators on height and top radii has been examined. A reduction in the height of SWCNC resonators gives rise to a considerable increase in mass sensitivity. The mass sensitivity of a 6 nm high SWCNC resonator can even reach a level of 10(-22) g. It is noteworthy that the top radii of SWCNC resonators have a slight effect on frequency shifts. Another interesting observed phenomenon is that a deviation in the height of 19.2° SWCNC resonators leads to little loss in precision of mass detection when the attached mass is smaller than 10(-20) g. This superior characteristic indicates that SWCNC-based mass detectors have great potential in practical applications.

Response of constrained glassy splay-bend and twist nematic sheets to light and heat.

A general approach is proposed to analyze the complex photo- or thermo-response of glassy splay-bend and twist nematic sheets with boundary constraints. The governing equations are two-dimensional, as in the classical plate theory. However, the solution can generate exact three-dimensional displacement and stress distributions within the interior of the sheets, except the boundary layer whose width is of the same order of the sheet thickness.