Factor analysis and GA-BP-ANN prediction of nitrogen diffusion behavior in underground laboratory under ventilation conditions.

Nitrogen is widely used in various laboratories as a suppressive gas and a protective gas. Once nitrogen leaks and accumulates in a such confined space, it will bring serious threats to the experimental staff. Especially in underground tunnels or underground laboratories where there is no natural wind, the threat is more intense. In this work, the ventilation design factors and potential leakage factors are identified by taking the leakage and diffusion of a large liquid nitrogen tank in China Jinping Underground Laboratory (CJPL) as an example. Based on computational fluid dynamics (CFD) research, the effects of fresh air inlet position, fresh air velocity, exhaust outlet position, leakage hole position, leakage hole size, and leaked nitrogen mass flow rate on nitrogen diffusion behavior in specific environments are discussed in detail from the perspectives of nitrogen concentration field and nitrogen diffusion characteristics. The influencing factors are parameterized, and the Latin hypercube sampling (LHS) is used to uniformly sample within the specified range of each factor to obtain samples that can represent the whole sample space. The nitrogen concentration is measured by numerical value, and the nitrogen diffusion characteristics are measured by category. The GA-BP-ANN numerical regression and classification regression models for nitrogen concentration prediction and nitrogen diffusion characteristics prediction are established. By using various rating indicators to evaluate the performance of the trained model, it is found that models have high accuracy and recognition rate, indicating that it is effective in predicting and determining the concentration value and diffusion characteristics of nitrogen according to ventilation factors and potential leakage factors. The research results can provide a theoretical reference for the parametric design of the ventilation system.

Potential roles of acyl homoserine lactones (AHLs) in nitrifying bacteria survival under certain adverse circumstances.

Potential roles of quorum sensing (QS) in nitrifying bacteria activity and ecology, particularly under adverse circumstances have been rarely reported. Herein, eight lab-scale nitrification sequencing batch reactors, with or without adding acyl homoserine lactones (AHLs) were operated under adverse circumstances respectively. The results indicated that the introduction of AHLs significantly enhanced the nitrogen removal efficiency in the presence of nitrification inhibitors (dicyandiamide, DCD), accelerated the low temperature (10 °C) group into stable stage, and improved the utilization efficiency of AHLs in these two groups. Community analysis and qPCR further confirmed that AHLs significantly increased the abundance of nitrifying bacteria in low temperature group and DCD group, especially AOB. For normal condition (28 °C, pH = 8) or low pH level (5.5), however, the AHLs had no significant effect. Canonical correspondence analysis showed that nitrifying bacteria positively responded to AHLs, indicating that adding AHLs was an effective strategy to regulate nitrification process. However, under acid conditions, the effect of this regulatory mechanism was not significant, indicating that the influence of pH on the system was greater than that of AHLs. This study demonstrated that exogenous AHLs could enhance the competitiveness of nitrifying bacteria to utilize more resource and occupy space under some adverse environmental conditions.

Identification of high-risk patients for development of type B aortic dissection based on novel morphological parameters.

Background: Predicting the development of sporadic type B aortic dissection (TBAD) always remains a difficult issue. This study aimed to identify high-risk patients for development of TBAD based on morphological parameters. Methods: This propensity-score-matched case-control study collected and reconstructed the computed tomography angiography of acute TBAD patients and hospital-based control participants without aortic dissection from January 2013 to December 2016. Multivariate regression analysis was used to calculate the adjusted odds ratio (aOR) and 95% confidence interval (CI). Discriminant and reclassification abilities were compared between our model and a previously established model. Results: Our study included 76 acute TBAD patients and 79 control patients (48 cases and 48 controls after propensity-score matching). The degree of question mark (aOR 1.07, 95% CI 1.04-1.11), brachiocephalic trunk diameter (aOR 1.49, 95% CI 1.20-1.85), brachiocephalic trunk angle (aOR 0.97, 95% CI 0.94-0.99), aortic root diameter (aOR 1.31, 95% CI 1.15-1.48), and aortic width (aOR 1.12, 95% CI 1.07-1.17) were associated with a significantly increased risk of TBAD formation. Similar findings were observed in the propensity-score matching and sensitivity analysis only including hyperacute TBAD patients. A novel prediction model was established based on the aforementioned parameters. The new model showed significantly improved discriminant ability compared with the previously established model (c-index 0.78 [95% CI 0.71-0.85] vs. 0.67 [95% CI 0.58-0.75], p = .03), driven by increased reclassification ability in identifying TBAD patients (NRI for events 0.16, 95% CI 0.02-0.30, p = .02). Conclusion: Morphological predictors, including the degree of question mark, aortic width, aortic root diameter, brachiocephalic trunk angle, and brachiocephalic trunk diameter, may be used to identify patients at high risk of TBAD.

The loss of helical flow in the thoracic aorta might be an identifying marker for the risk of acute type B aortic dissection.

BACKGROUND AND OBJECTIVE: The occurrence of acute type B aortic dissection (TBAD) remained unclear. This study aimed to investigate the association between flow features and hemodynamic parameters in aortas that demonstrated the risk of TBAD occurrence. METHODS: The geometries of 15 hyperacute TBAD and 12 control patients (with healthy aorta) were reconstructed from computed tomography angiography images. Pre-TBAD models were then obtained by eliminating the dissection flaps. Flow features and hemodynamic parameters, including wall shear stress-related parameters and helicities, were compared between pre-TBAD and control models using computational fluid dynamics. RESULTS: There were no significant differences in baseline characteristics and anatomical parameters between the two groups. Significant contralateral helical blood flow was present in the healthy thoracic aorta, while almost no helical flow was observed in the pre-TBAD group. In addition, the mean normal transverse wall shear stress (NtransWSS) was significantly higher in the pre-TBAD group (aortic arch 0.49±0.09 vs. 0.40±0.05, P = 0.04; descending aorta: 0.46±0.05 vs. 0.33±0.02, P<0.01). Moreover, a significantly negative correlation was found between helicity and NtransWSS in the descending aorta. Moreover, the location of primary tears in 12 pre-TABD subjects matched well with regions of high NtransWSS. CONCLUSIONS: Loss of helical flow in the aortic arch and descending aorta may be a major flow feature in patients with underlying TBAD, resulting in increased flow disturbance and wall lesions.

Molecular Dynamics Study on Hugoniot State and Mie-Grüneisen Equation of State of 316 Stainless Steel for Hydrogen Storage Tank.

To promote the popularization and development of hydrogen energy, a micro-simulation approach was developed to determine the Mie-Grüneisen EOS of 316 stainless steel for a hydrogen storage tank in the Hugoniot state. Based on the combination of the multi-scale shock technique (MSST) and molecular dynamics (MD) simulations, a series of shock waves at the velocity of 6-11 km/s were applied to the single-crystal (SC) and polycrystalline (PC) 316 stainless steel model, and the Hugoniot data were obtained. The accuracy of the EAM potential for Fe-Ni-Cr was verified. Furthermore, Hugoniot curve, cold curve, Grüneisen coefficient (γ), and the Mie-Grüneisen EOS were discussed. In the internal pressure energy-specific volume (P-E-V) three-dimensional surfaces, the Mie-Grüneisen EOSs show concave characteristics. The maximum error of the calculation results of SC and PC is about 10%. The results for the calculation deviations of each physical quantity of the SC and PC 316 stainless steel indicate that the grain effect of 316 stainless steel is weak under intense dynamic loads, and the impact of the grains in the cold state increases with the increase in the volume compression ratio.

Effects of different bypass surgeries on LSA revascularization in patients with left subclavian occlusion.

INTRODUCTION: Left subclavian artery (LSA) bypass surgery is mainly carried out for patients with severe left subclavian occlusion. This article aimed to evaluate the hemodynamic effects of different surgical bypass modes on LSA revascularization. METHODS: Three-dimensional models of the aorta were reconstructed from CTA images of a patient with LSA occlusion, a patient with type B aortic dissection with LSA coverage during thoracic endovascular aortic repair, and a healthy 74-year-old man, resulting in six modes for each person: healthy LSA mode, LSA occlusion mode and four bypass modes. Hemodynamic parameters, including flow field, flow distribution, pressure gradient, and wall shear stress, were calculated using computational fluid dynamics. RESULTS: After LSA bypass surgery, distal LSA blood flow resulting from left common carotid artery (LCCA) to distal LSA bypass was 100% of that in the healthy mode, while the other modes yielded flows at least 91%. Moreover, reversed flow only completely disappeared with LCCA to distal LSA bypass, whereas reverse flow was observed in the other three modes in early systole. CONCLUSION: Left common carotid artery to distal LSA bypass can effectively reduce reverse blood flow in the left vertebral artery, and it is a feasible, effective, and safe option for LSA revascularization in patients with left subclavian occlusion.

Deciphering the Molecular Signatures Associated With Resistance to Botrytis cinerea in Strawberry Flower by Comparative and Dynamic Transcriptome Analysis.

Gray mold caused by Botrytis cinerea, which is considered to be the second most destructive necrotrophic fungus, leads to major economic losses in strawberry (Fragaria × ananassa) production. B. cinerea preferentially infects strawberry flowers and fruits, leading to flower blight and fruit rot. Compared with those of the fruit, the mechanisms of flower defense against B. cinerea remain largely unexplored. Therefore, in this study, we aimed to unveil the resistance mechanisms of strawberry flower through dynamic and comparative transcriptome analysis with resistant and susceptible strawberry cultivars. Our experimental data suggest that resistance to B. cinerea in the strawberry flower is probably regulated at the transcriptome level during the early stages of infection and strawberry flower has highly complex and dynamic regulatory networks controlling a multi-layered defense response to B. cinerea. First of all, the higher expression of disease-resistance genes but lower expression of cell wall degrading enzymes and peroxidases leads to higher resistance to B. cinerea in the resistant cultivar. Interestingly, CPKs, RBOHDs, CNGCs, and CMLs comprised a calcium signaling pathway especially play a crucial role in enhancing resistance by increasing their expression. Besides, six types of phytohormones forming a complex regulatory network mediated flower resistance, especially JA and auxin. Finally, the genes involved in the phenylpropanoid and amino acids biosynthesis pathways were gene sets specially expressed or different expression genes, both of them contribute to the flower resistance to B. cinerea. These data provide the foundation for a better understanding of strawberry gray mold, along with detailed genetic information and resistant materials to enable genetic improvement of strawberry plant resistance to gray mold.

Reproduction response of Colletotrichum fungi under the fungicide stress reveals new aspects of chemical control of fungal diseases.

Systemic fungicides and antifungals are used as frontline treatments for fungal diseases in plants and humans. It is generally accepted that fungicides will bring significant negative side-effects to the environment and result in fungicide resistance in the pathogenic fungi. Although previous research has focused on fungicide application rates and fungal resistance for a long time, little attention has been paid to fungicide residues after treatment, especially their potential role in fungal growth and sporulation. Here we investigated the effect of fungicides at sublethal concentrations on fungal sporulation. The results showed that two kinds of 14α-demethylase inhibitors (DMIs) fungicides increased the number of isolates of Colletotrichum spp. to sporulate on PDA. Both on PDA medium and plant tissue, low concentration of DMI fungicides could promote spore production of Colletotrichum spp., whereas pyraclostrobin, a quinone outside inhibitor (QoIs), had no significant effects on sporulation of Colletotrichum spp. Transcriptomic analysis suggested that the DMIs fungicide stress signal may be transmitted to the central regulatory pathway through the FluG-mediated signalling pathway, and further confirmed the morphological effect of DMI fungicide on promoting sporulation of Colletotrichum. To our knowledge, this is the first study to provide insights into the reproductive response of fungi in response to fungicide stress. Our findings indicate that fungicides have two-way effects on the growth and reproduction of pathogenic fungi and provide a new basis for the scientific and rational use of fungicides.

Function of quorum sensing and cell signaling in wastewater treatment systems.

Quorum sensing (QS) is a communication mode between microorganisms to regulate bacteria ecological relations and physiological behaviors, thus achieve the physiological function that single bacteria cannot complete. This phenomenon plays important roles in the formation of biofilm and granular sludge, and may be related to enhancement of some functional bacteria activity in wastewater treatment systems. There is a need to better understand bacterial QS in engineered reactors, and to assess how designs and operations might improve the removal efficiency. This article reviewed the recent advances of QS in several environmental systems and mainly analyzed the regulation mechanism of QS-based strategies for biofilm, granular sludge, functional bacteria, and biofouling control. The co-existences of multiple signal molecules in wastewater treatment (WWT) processes were also summarized, which provide basis for the future research on the QS mechanism of multiple signal molecules' interaction in WWT. This review would present some prospects and suggestions which are of practical significance for further application.

Comparative transcriptome analysis reveals fruit discoloration mechanisms in postharvest strawberries in response to high ambient temperature.

The aim of this study was to examine both physiological and molecular evidences related to fruit discoloration in postharvest strawberries under high ambient temperature. The results showed the total anthocyanin and their main components in the strawberries under 35 °C were greatly increased due to the significant up-regulations of anthocyanin biosynthetic genes and transportation genes. High ambient temperature greatly improved the activities of peroxidase (POD) and enhanced gene expressions of POD3, POD6 and POD63. At the same time, high storage temperature activated laccase genes expression including laccase-9 and laccase-14, which was closely related to anthocyanin degradation. Levels of reactive oxygen species (ROS) metabolism were also increased under high ambient temperature at transcript levels. Therefore, we concluded that high ambient temperature could enhance anthocyanin accumulation and degradation at the same time, which maybe the main reasons for the fruits discoloration of postharvest strawberries under high ambient temperature.

Investigation of the Propagation of Stress Wave in Nickel-Titanium Shape Memory Alloys.

Based on irreversible thermodynamic theory, a new constitutive model incorporating two internal variables was proposed to investigate the phase transformation and plasticity behavior in nickel-titanium (NiTi) shape memory alloys (SMAs), by taking into account four deformation stages, namely austenite elastic phase, phase transition, martensitic elastic phase, and plastic phase. The model using the material point method (MPM) was implemented by the FORTRAN code to investigate the stress wave and its propagation in a NiTi rod. The results showed that its wave propagation exhibited martensitic and austenitic elastic wave, phase transition wave, and plastic wave. However, a double-wave structure including the martensitic and austenitic elastic wave and plastic wave occurred when the martensitic elastic wave reached the phase transformation wave. Thus, the reflection wave at a fixed boundary exhibited a different behavior compared with the elastic one, which was attributed to the phase transition during the process of reflection. It was found that the stress increment was proportional to the velocity of phase transition wave after the stress wave reflection. In addition, the influences of loading direction and strain rate on the wave propagation were examined as well. It was found that the phase transition wave velocity increased as the strain rate increased. The elastic wave velocity of martensite under compressive conditions was larger than that under tensile loading. In contrast, the plastic wave velocity under compression was less than that subjected to the tensile load.

[Effects of exogenous ABA and GA3 on sugar concentration in flesh of cara cara navel orange].

The concentration of glucose, fructose, sucrose and total sugar were determined after exogenous ABA and GA3 treatment during young period of fruit and before fruit coloring in flesh of Cara Cara Navel Orange. The results showed that 10 mg x L(-1) ABA treatment improved glucose, fructose and total sugar concentration significantly or very significantly, 50 mg x L(-1) ABA treatment improved sucrose concentration very significantly, but 100 mg x L(-1) ABA treatment reduced glucose concentration very significantly. GA3 treatment of lower and middle concentrations (10, 50 and 250 mg x L(-1)) improved sucrose concentration very significantly, 10 mg x L(-1) GA3 treatment had no remarkable effect on glucose and fructose concentration but improved total sugar concentration very significantly, GA3 treatment of 50, 250 and 500 mg x L(-1) decreased glucose, fructose and total sugar concentration very significantly. Therefore, ABA treatment of lower concentration could improve one or several kinds of sugar concentration, but GA3 treatment of higher concentration (250 and 500 mg x L(-1)) prohibited sugar accumulation in flesh of Cara Cara Navel Orange seriously.

[Effects of bagging on pigment, sugar and endogenous hormone contents of Cara Cara orange flesh].

This paper studied the effects of bagging during the period from young fruit formation to fruit coloration on the contents of pigment, sugar and endogenous hormone in Cara Cara orange flesh. The results showed that bagging could significantly increase the lycopene and beta-carotene contents of matured fruit, but didn't have any effects on its GA and ABA contents. The GA content decreased rapidly during fruit-expanding period, and maintained at a lower level in the period from fruit coloration to maturing. The ABA content reached the maximum when the bag was removed, decreased rapidly then, and there was a small peak before fruit maturation. Glucose and fructose contents were decreased, while sucrose content was increased significantly. No significant change was observed in total sugar content.

[Expression of p15 protein in poorly differentiated nasopharyngeal carcinoma].

OBJECTIVE: To explore the role of p15 protein in the pathogenesis of poorly differentiated nasopharyngeal carcinoma (NPC). METHOD: Using immunohistochemical LSAB (Labeled Streptavidin Biotin method), we examined 55 samples of poorly differentiated NPC and 15 samples of nasopharyngeal normal tissue for expression of p15 protein. RESULT: The p15 protein expression was located in the cytoplasm and nuclear membranes. The positive rate of p15 protein in NPC is significantly lower than that in normal tissue (P < 0.05). Important correlations were found between the p15 protein expression and clinic stages, T classification of NPC. But p15 protein wasn't correlated to neck lymph node metastasis and 5-years survival rate. CONCLUSION: The absence of p15 protein may play an important role in the pathogenesis and development of NPC, the expression of p15 protein may be used to evaluate the biological behavior of NPC.