Analytical vectorial structure of non-paraxial four-petal Gaussian beams in the far field

The analytical vectorial structure of non-paraxial four-petal Gaussian beams(FPGBs) in the far field has been studied based on vector angular spectrum method and stationary phase method. In terms of analytical electromagnetic representations of the TE and TM terms, the energy flux distributions of the TE term, the TM term, and the whole beam are derived in the far field, respectively. According to our investigation, the FPGBs can evolve into a number of small petals in the far field. The number of the petals is determined by the order of input beam. The physical pictures of the FPGBs are well illustrated from the vectorial structure, which is beneficial to strengthen the understanding of vectorial properties of the FPGBs

Vectorial structure of a hard-edged-diffracted four-petal Gaussian beam in the far field

Based on the vector angular spectrum method and the stationary phase method and the fact that a circular aperture function can be expanded into a finite sum of complex Gaussian functions, the analytical vectorial structure of a four-petal Gaussian beam (FPGB) diffracted by a circular aperture is derived in the far field. The energy flux distributions and the diffraction effect introduced by the aperture are studied and illustrated graphically. Moreover, the influence of the f-parameter and the truncation parameter on the nonparaxiality is demonstrated in detail. In addition, the analytical formulas obtained in this paper can degenerate into un-apertured case when the truncation parameter tends to infinity. This work is beneficial to strengthen the understanding of vectorial properties of the FPGB diffracted by a circular aperture

Effects of Cr and Zr Addition on Microstructures, Compressive Properties, and Abrasive Wear Behaviors of In Situ TiB2/Cu Cermets

In situ micro-TiB2/Cu cermets with a different TiB2 content (40, 50, and 60 vol %) were successfully fabricated by combustion synthesis (CS) and hot press consolidation in Cu-Ti-B systems. In addition, different contents of Cr and Zr were added to the Cu-Ti-B systems. The microstructure, mechanical properties, and abrasive wear properties of the TiB2/Cu cermets were investigated. As the ceramic content increased, the yield strength and compressive strength of the cermets were found to increase, while the strain decreased. An increase in load and abrasive particle size caused the wear volume loss of the TiB2/Cu cermets to increase. When the ceramic content was 60 vol %, the wear resistance of the TiB2/Cu cermets was 3.3 times higher than that of pure copper. The addition of the alloying elements Zr and Cr had a significant effect on the mechanical properties of the cermets. When the Cr content was 5 wt %, the yield strength, ultimate compressive strength, and microhardness of the cermets reached a maximum of 997 MPa, 1183 MPa, and 491 Hv, respectively. Correspondingly, when the Zr content was 5 wt %, those three values reached 1764 MPa, 1967 MPa, and 655 Hv, respectively, which are 871 MPa, 919 MPa, and 223 Hv higher than those of the unalloyed cermets. The wear mechanism of the in-situ TiB2/Cu cermets, and the mechanisms by which the strength and wear resistance were enhanced by the addition of Zr, were preliminarily revealed

Residential Environment, Diet and Risk of Stomach Cancer: a Case-control Study in Linzhou, China.

A case-control study was conducted to investigate risk factors for stomach cancer in a rural population in China. Linzhou Cancer Registry was used to identify cases of stomach cancer, aged between 30 and 75 years, diagnosed between January 1998 and April 1999. Three neighbourhood controls were selected for each case, matched according to age, sex and village of residence. A total of 210 cases and 630 controls were interviewed. Conditional logistic regression was used to estimate odds ratios (OR) for factors associated with the risk of cancer. Among characteristics of the residential environment, significantly increased risk was found for: frequent irritation on eyes or throat by soot (OR 5.54, 95% CI 1.42-21.65, p for trend <0.01). This effect was particularly strong in women (OR 19.5, 95% CI 1.28-297.09, p for trend =0.01). Dietary factors that were significantly associated with an increased risk were food grains other than rice, wheat and maize (OR 2.93, 95% 1.16-7.38), pickled or salted vegetables (OR 3.99, 95% CI 1.63-9.75) and preference for a high salt diet (OR 2.58, 95% CI 1.56-4.26). The consumption of vegetables showed a protective effect with an odds ratio of 0.27 (95% CI 0.11-0.61). It follows that a developing economy and improvement in living standards, with associated increased intake of fruit and vegetables and reduced consumption of salt, can contribute to a reduction in the incidence of stomach cancer in the Linzhou population

Risk factors for oesophageal cancer in Linzhou, China: a case-control study.

Linzhou City has one of the highest incidences of oesophageal cancer in China, and in the world. A case-control study was here conducted to investigate potential risk factors in this area. Linzhou Cancer Registry was used to identify cases of oesophageal cancer, aged between 30 and 75, diagnosed between January 1998 and April 1999. Three neighbourhood controls were selected for each case, matched according to age, sex and village of residence. A total of 211 cases and 633 controls were interviewed. A strong association was found between socio-economic status and the risk of oesophageal cancer. Increased income, residential space and education were all significantly associated with a decreased risk (OR 0.54, 0.36 and 0.30 respectively). Using a drinking water source other than tap water was significantly associated with an increased risk (OR 5.49). The consumption of beans, vegetables and vinegar all showed a protective effect with odds ratios of 0.37, 0.44 and 0.37 respectively. Preferences for a low salt diet or a high salt diet were both associated with an increased risk. It can be concluded that in Linzhou, oesophageal cancer is a disease related to poverty. Having a drinking water source other than tap water increases the risk of oesophageal cancer. As in other populations, a high consumption of vegetables and beans are associated with a decreased risk and a preference for a high salt diet is associated with an increased risk

Isolation, Optimization of Fermentation Conditions, and Characterization of an Exopolysaccharide from Pseudoalteromonas agarivorans Hao 2018

In recent years, the wide application of exopolysaccharides (EPSs) in food, cosmetics, medicine, and other fields has drawn tremendous attention. In this study, an EPS produced by Pseudoalteromonas agarivorans Hao 2018 was isolated and purified, and its fermentation conditions were optimized. Its structure and biological functions were also studied. The purity and molecular weight of EPS were determined by high performance liquid chromatography (HPLC), and the EPS exhibited a number average of 2.26 &times; 105 and a weight average of 2.84 &times; 105. EPS has good adsorption for Cu2+ and Pb2+. The adsorption rates can reach up to 69.79% and 82.46%, respectively. The hygroscopic property of EPS was higher than that of chitosan, but slightly lower than that of sodium hyaluronate. However, the water-retaining activity of EPS was similar to that of chitosan and sodium hyaluronate. EPS has strong ability to scavenge free radicals, including OH radical and O2&minus; radical. Further, its activity on O2&minus; radicals has similarities with that of vitamin C. EPS has broad application prospects in many fields, such as cosmetics, environmental protection

Effects of Cutting Intensity on Soil Physical and Chemical Properties in a Mixed Natural Forest in Southeastern China

The mixed Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), Masson’s pine (Pinus massoniana Lamb.), and hardwood forest is a major forest type in China and of national and international importance in terms of its provision of both timber and ecosystem services. However, over-harvesting has threatened its long-term productivity and sustainability. We examined the impacts of timber harvesting intensity on soil physical and chemical properties 10 and 15 years after cutting using the research plots established with a randomized block design. We considered five treatments, including clear cutting and low (13.0% removal of growing stock volume), medium (29.1%), high (45.8%), and extra-high (67.1) intensities of selective cutting with non-cutting as the control. The impact on overall soil properties derived from principal component analysis showed increasing with a rise in cutting intensity, and the most critical impact was on soil nutrients, P and K in particular. Soil nutrient loss associated with timber harvesting even at a low cutting intensity could lead to nutrient deficits in this forest although most of the soil physical properties could be recovered under the low and medium intensities of cutting. These results indicate that clear cutting and the selective cutting of extra-high and high intensities should be avoided in this type of forest in the region

An ultra-compact promoter drives widespread neuronal expression in mouse and monkey brains

Summary: Promoters are essential tools for basic and translational neuroscience research. An ideal promoter should possess the shortest possible DNA sequence with cell-type selectivity. However, whether ultra-compact promoters can offer neuron-specific expression is unclear. Here, we report the development of an extremely short promoter that enables selective gene expression in neurons, but not glial cells, in the brain. The promoter sequence originates from the human CALM1 gene and is only 120 bp in size. The CALM1 promoter (pCALM1) embedded in an adeno-associated virus (AAV) genome directed broad reporter expression in excitatory and inhibitory neurons in mouse and monkey brains. Moreover, pCALM1, when inserted into an all-in-one AAV vector expressing SpCas9 and sgRNA, drives constitutive and conditional in vivo gene editing in neurons and elicits functional alterations. These data demonstrate the ability of pCALM1 to conduct restricted neuronal gene expression, illustrating the feasibility of ultra-miniature promoters for targeting brain-cell subtypes