Dust generation characteristics during the wet-mix shotcrete process in mines and the preparation of a composite dust-reducing additive

The dust pollution during the wet-mix shotcrete process in mines constitutes a crucial factor limiting the efficiency, cleanliness, and safety of wet-mix shotcrete support projects. To mitigate the potential harm to workers and enhance the dust control and occupational health capabilities of mines, a dynamic model for the dust generation during wet-mix shotcrete is constructed using the aerosol mechanics and the Hertz-Mindlin collision theory. In consideration of the characteristics of the wet-mix shotcrete process, a similar experimental apparatus for wet-mix shotcrete is established to analyze the dust generation characteristics under different process conditions. Additionally, focusing on the dust reduction mechanism of additives in the wet-mix shotcrete process, a study is conducted on the dust reduction performance of additives, leading to the formulation of a high-performance composite dust-reducing additive suitable for the wet-mix shotcrete process. The results show that the aerosol particles dispersed in the air during the wet-mix shotcrete process predominantly have diameters below 2 μm, with particles below 2 μm constituting over 90% of the particle count. Dust generation during wet-mix shotcrete is primarily influenced by factors such as spray distance, spray pressure, and water-cement ratio. The optimal spray distance should avoid extremes, and as the distance increases, the particle concentration shows a trend of initially decreasing and then increasing. Similarly, a spray pressure of 0.4 MPa is deemed suitable, and excessively high pressure leads to an increased rebound rate and dust concentration, while very low pressure results in insufficient kinetic energy for material adhesion to the sprayed surface. Simultaneously, maintaining material fluidity and reducing rebound rates and dust generation can be achieved by lowering the water-cement ratio. The composite dust-reducing additive, composed of setting accelerators, chelating agents, early strength agents, binders, and surfactants, is developed. Through orthogonal and optimization experiments, the final formula is determined as A-55%, B-3%, C-4.5%, D-0.5%, E-0.15%, and water-36.85%. Incorporating this composite dust-reducing additive reduces dust concentration during the wet-mix shotcrete process by approximately 57%, effectively lowering dust emissions and demonstrating a significant dust reduction effect

Identification of RNA silencing suppressor encoded by citrus chlorotic dwarf-associated virus

IntroductionCitrus chlorotic dwarf-associated virus (CCDaV) is an economically important citrus virus associated with leaf curling, deformation, and chlorosis found in China. Plants have evolved RNA silencing to defend against viral infections; however, the mechanism by which CCDaV suppresses RNA silencing in citrus remains unknown.MethodsSix proteins encoded by CCDaV were ectopically expressed in Nicotiana benthamiana 16c using the pCHF3 vector to identify RNA-silencing suppression activities.ResultsV2 protein encoded by CCDaV suppressed local RNA silencing and systemic RNA silencing triggered by GFP RNA, but did not impede short-distance movement of the RNA silencing signal in N. benthamiana 16c. GFP fluorescence observations showed that the ability of V2 protein to suppress RNA silencing was weaker than tomato bushy stunt virus P19. Deletion analysis showed that the putative nuclear localization signal (NLS, 25–54 aa) was involved in the RNA silencing suppression activity of V2 protein. Furthermore, V2 protein cannot block dsRNA-triggered RNA silencing. The subcellular localization assay suggested that V2 protein was localized to nucleus of N. benthamiana.ConclusionOverall, the results of this study demonstrate that CCDaV-V2 acts as an activity of silencing suppression. This is the first reported RNA-silencing suppressor encoded by Citlodavirus and will be valuable in revealing the molecular mechanism of CCDaV infection

Quasi-three-level Model Applied to Measured Spectra of Nonlinear Absorption and Refraction in Organic Molecules

Materials with a large nonlinear refractive index (2) and relatively small linear and nonlinear absorption losses, namely, two-photon absorption (2PA, of coefficient 2), have long been sought after for applications such as all-optical switching (AOS). Here we experimentally determine the linear and 2PA properties of several organic molecules, which we approximate as centrosymmetric, and use a simplified essential-state model (quasi-three-level model) to predict the dispersion of 2. We then compare these predictions with experimental measurements of 2 and find good agreement. Here “quasi”-three-level means using a single one-photon allowed intermediate state and multiple (here two) two-photon allowed states. This also allows predictions of the figure-of-merit (FOM), defined as the ratio of nonlinear refractive phase shift to the 2PA fractional loss, that determines the viability for such molecules to be used in device applications. The model predicts that the optimized wavelength range for a large FOM lies near the short wavelength linear absorption edge for cyanine-like dyes where the magnitude of 2 is quite large. However, 2PA bands lying close to the linear absorption edge in certain classes of molecules can greatly reduce this FOM. We identify two molecules having a large FOM for AOS. We note that the FOM is often defined as the ratio of real to imaginary parts of the third-order susceptibility ((3)) with multiple processes leading to both components. As explained later in this paper, such definitions require care to only include the 2PA contribution to the imaginary part of (3) in regions of transparency.Abstract © 2016 Optical Society of Americ

A Large-Scale Zebrafish Gene Knockout Resource for the Genome-Wide Study of Gene Function

With the completion of the zebrafish genome sequencing project, it becomes possible to analyze the function of zebrafish genes in a systematic way. The first step in such an analysis is to inactivate each protein-coding gene by targeted or random mutation. Here we describe a streamlined pipeline using proviral insertions coupled with high-throughput sequencing and mapping technologies to widely mutagenize genes in the zebrafish genome. We also report the first 6144 mutagenized and archived F1’s predicted to carry up to 3776 mutations in annotated genes. Using in vitro fertilization, we have rescued and characterized ~0.5% of the predicted mutations, showing mutation efficacy and a variety of phenotypes relevant to both developmental processes and human genetic diseases. Mutagenized fish lines are being made freely available to the public through the Zebrafish International Resource Center. These fish lines establish an important milestone for zebrafish genetics research and should greatly facilitate systematic functional studies of the vertebrate genome

THE MULTILEVEL PARTICLE VIA SPACE-DSICRETIZED EULER-MARUYAMA

Master'sMASTER OF SCIENC

The Preparation and Properties of Low-Nitrogen Nitrocellulose by Alkaline Denitration

Waste high-nitrogen nitrocellulose (NC) has always been disposed of as hazardous material for destruction, and has not been recycled as a resource. The present work describes how waste high-nitrogen NC may be converted to low-nitrogen NC via an alkaline denitration reaction between sodium hydrosulfide and the nitrate ester groups, in order to control and reduce the nitrogen content for industrial products. Scanning electron microscopy (SEM), infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance spectroscopy (1H NMR) and X-ray diffraction (XRD) were used to detected the changes in the surface morphology and chemical structure of the NC samples. TG-DSC tests analyzed the decomposition temperature and the heat released on thermal decomposition, and the explosion heat was obtained by calorimetry. The results demonstrated that the denitration reaction does not destroy the skeletal structure of NC. Notably, the nitrogen content of NC may be reduced from 12.92 to 10.74%, generating the level for industrial products (N <12%). Moreover, NC samples with different nitrogen contents have similar decomposition trends and decomposition temperatures, but the heat released is gradually decreased and the explosion heat is significantly reduced, and confirms the successful partial removal of nitrate ester groups from NC. Therefore, the alkaline denitration affords a potential method for recycling waste high-nitrogen NC

Detection of Citrus yellow vein clearing virus by Quantitative Real-time RT-PCR

To develop a rapid and reliable detection method for Citrus yellow vein clearing virus (CYVCV), a quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) system based on SYBR Green I was established by using a pair of specific primers designed from its conserved coat protein gene. The sensitivity, specificity, and applicability of the system were evaluated accordingly. The results showed that amplicons were produced from CYVCV isolates, whereas no amplicons from non-CYVCV citrus virus samples, including Citrus tristeza virus (CTV) and Citrus tatter leaf virus (CTLV), were obtained. The sensitivity of the qRT-PCR was 100-fold higher than that of conventional RT-PCR. An excellent linear correlation (R2 = 0.999) was obtained from two standard curves of cRNA, and the amplification efficiency was 102%. The data from field citrus samples detection showed that the qRT-PCR system could be used in determining the concentration of CYVCV in different citrus species