Study on damage mechanism and damage distribution of the rear plate under impact of debris cloud

The debris cloud generated by the hypervelocity impact(HVI)of orbiting space debris directly threatens the spacecraft.A full understanding of the damage mechanism of rear plate is useful for the optimal design of protective structures.In this study,the hypervelocity yaw impact of a cylindrical aluminum projectile on a double-layer aluminum plate is simulated by the FE-SPH adaptive method,and the damage process of the rear plate under the impact of the debris cloud is analyzed based on the debris cloud structure.The damage process can be divided into the main impact stage of the debris cloud and the structural response of the rear plate.The main impact stage lasts a short time and is the basis of the rear plate damage.In the stage of structure response,the continuous deformation and inertial motion of the rear plate dominate the perforation of the rear plate.We further analyze the damage mechanism and damage distribution characteristics of the rear plate in detail.Moreover,the connection between velocity space and position space of the debris cloud is established,which promotes the general analysis of the damage law of debris cloud.Based on the relationship,the features of typical damage areas are identified by the localized fine analysis.Both the cumulative effect and structural response cause the perforation of rear plate;in the non-perforated area,cratering by the impact of hazardous fragments is the main damage mode of the rear plate.

Enhanced Photovoltaic Properties for Rear Passivated Crystalline Silicon Solar Cells by Fabricating Boron Doped Local Back Surface Field

In order to enhance the p-type doping concentration in the LBSF, boron was added into the aluminum paste and boron doped local back surface field（B-LBSF） was successfully fabricated in this work. Through boron doping in the LBSF, much higher doping concentration was observed for the B-LBSF over the Al-LBSF. Higher doping concentration in the LBSF is expected to lead to better rear passivation and lower rear contact resistance. Based on one thousand pieces of solar cells for each type, it was found that the rear passivated crystalline silicon solar cells with B-LBSF showed statistical improvement in their photovoltaic properties over those with Al-LBSF.

Effects of rearing system and antibiotic treatment on immune function,gut microbiota and metabolites of broiler chickens

Background:In China,cage systems with a high space utilization have gradually replaced ground litter systems,but the disease incidence of chickens in cages is higher.Broilers in the ground litter pens may be stimulated by more environmental microbes during the growth process and show strong immune function and status,but knowledge of which microbes and their metabolites play an immunomodulatory role is still limited.This study aimed to explore the differences and correlations in the immune function,gut microbiota and metabolites and the importance of gut microbiota of broilers raised in cages and ground litter pens.Methods:The experiment involved a 2×2 factorial arrangement,with rearing systems(cages or ground litter pens)and antibiotic treatment(with or without broad-spectrum antibiotics in drinking water)as factors.Results:The results showed that,compared with the cage group,the ground litter broilers had stronger nonspecific immune function(Macrophages%and NO in blood),humoral immune function(IgG in blood,LPS stimulation index in ileum)and cellular immune function(T%,Tc%,ConA stimulation index and cytokines in blood).Antibiotic(ABX)treat-ment significantly reduced nonspecific immune function(Macrophages%and NO in blood,iNOS and Mucin2 mRNA expression in ileum),humoral immune function(IgG in blood and sIgA in ileum)and cellular immune function(T%and cytokines in blood,Th and Tc ratio,TLRs and cytokines mRNA expression in ileum).Furthermore,the ground litter broil-ers had higherαdiversity of microbiota in ileum.The relative abundance of Staphylococcus,Jeotgalicoccus,Jeotgalibaca and Pediococcus in the ileum of ground litter broilers were higher.ABX treatment significantly reduced theαdiversity of ileal microbiota,with less Chloroplast and Mitochondria.In addition,the levels of acetic acid,isobutyric acid,kynurenic acid and allolithocholic acid in the ileum of ground litter broilers were higher.Spearman correlation analysis showed that Jeotgalibaca,Pediococcus,acetic acid,kynurenic acid and allolithocholic acid were related to the immune function.Conclusions:There were more potential pathogens,litter breeding bacteria,short-chain fatty acids,kynurenine,allolithocholic acid and tryptophan metabolites in the ileum of broilers in ground litter pens,which may be the reason for its stronger immune function and status.

Performance of Two Food Substrates in the Mass Rearing of Bactrocera dorsalis Hendel (Diptera: Tephritidae)

The fruit fly Bactrocera dorsalis Hendel is a major constraint to mango production in Burkina Faso. The objective of this study was to evaluate the performance of two types of food substrates in optimizing the mass rearing of B. dorsalis larvae. For this purpose, 200 eggs of B. dorsalis were divided into four batches of 50 eggs and incubated in Petri dishes containing the different food substrates (Diet 1 and Diet 2). This method was used to evaluate the rate and duration of egg hatching, as well as the development time of the different larval stages. In addition, 1200 pupae divided into four batches of 300 pupae, contained in PVC tubes, were placed inside the rearing cages to monitor the emergence of B. dorsalis. Ten pairs of B. dorsalis were placed in rearing cages and fed with Enzymatic Yeast Hydrolysate and sugar to evaluate the fecundity of female flies and the survival of both sexes. The developmental cycle length in Diet 1 and Diet 2 was 23.03 days and 23.24 days, respectively. Fecundity duration ranged from 57.75 ± 2.29 to 109.81 ± 3.81 days for females from Diet 1 and Diet 2, respectively. The pupal hatching rate varied significantly (P B. dorsalis, but the spawning index was 4 times higher with Diet 1. Most of the components of Diet 1 are available on the local market and are cheaper. Thus, we recommend the use of Diet 1 for B. dorsalis larvae mass rearing.

Effects of Different Rearing Modes on the Muscular Histological Traits and Meat Tenderness of Chicken

[ Objective] The aim of this experiment was to explore the effects of different rearing modes on muscle histological traits and muscle ten demess and to provide theoretical basis for regulating chicken meat quality. [ Method] The effects of outdoor rearing, indoor rearing and cage rea ring modes on the muscular histological traits and meat tenderness of Hetian chicken at the age of 8 weeks, 12 weeks and 16 weeks were re searched. [Result] The results showed that the breast and thigh muscle fibre diameter and muscle shear force of outdoor rearing chicken were sig nificently higher than that of cage rearing chicken （ P 〈 0.05）, and muscle fibre density was significantly lower than that of cage rearing chicken （ P 〈 0.05）. With aging, the muscle fibre diameter and shear force increased and muscle fibre density decreased （ P 〈 0.05）. The muscle fibre di ameter and shear force of male were higher than that of female. The correlation analysis showed that the breast muscle shear force had a signifi cantly positive relation with fibre diameter and negative relation with fibre density （ P 〈 0.05）, but thigh muscle shear force had an insignificantly pos itive relation with fibre diameter and fibre density. [ Condusion] Muscular histological traits varied in different rearing modes, and the outdoor rearing promoted the muscular fibre development and increased the muscular shear force.

Ballistic performance of spaced multi-ply soft fabrics: Experimental and numerical investigation

It has been reported that the ply gap influences the ballistic resistance of spaced multi-ply fabric systems,but its working mechanism was not well-understood. This paper reports the experimental and numerical approaches and results of an investigation on the mechanisms that enable the improved ballistic performance of spaced multi-ply systems. Penetration tests were performed over a range of impact velocities ranging from 200 m/s to 400 m/s. The results confirmed that the ply gap is beneficial to the energy absorption capability of the systems. This is because the front plies tend to absorb more energy when they are not immediately constrained by the rear plies. During a ballistic event, the gap relieves the reflection of the compressive pulse, prolonging the projectile engagement time with the front plies;on the other hand, the rear plies become increasingly less active in dissipating energy as the gap increases.When the gap is sufficiently widened to avoid any interference between the plies before the failure of the front ply, the responses of the whole system no longer vary. It was also found that the ballistic performance of the spaced systems is influenced by ply thickness, impact velocity, and the stacking order of the ply gap.

Impact of numerous larval diets on the biology of pink bollworm Pectinophora gossypiella(Saunders)(Lepidoptera:Gelechiidae)under laboratory conditions

Background Pink bollworm,Pectinophora gossypiella(Saunders)(Lepidoptera:Gelechiidae)has become a poten-tial pest of cotton by causing substantial yield losses around the world including Pakistan.Keeping in view the facts like limited research investigations,unavailability,and high cost of artificial diet’s constituents and their premixes,the present research investigations on the dietary aspect of P.gossypiella were conducted.The larvae of P.gossypiella were reared on different diets that were prepared using indigenous elements.The standard/laboratory diet com-prised of wheat germ meal 34.5 g,casein 30.0 g,agar–agar 20.0 g,sucrose 10.0 g,brewer’s yeast 5.0 g,α-cellulose 1.0 g,potassium-sorbate1.5 g,niplagin 0.5 g,decavitamin 0.01 g,choline-chloride 0.06 g,maize-oil 3.30 g,honey 2.0 g,and water 730.0 mL.Alternatives to cotton bolls and wheat germ meal were okra seed sprouts,okra fruit,cottonseed meal,and okra seed meals,which were included in the study to introduce an efficient and economic mass-rearing system.Results The larval development completed in 19.68d±0.05 d with a weight of 20.18mg±0.20 mg at the fourth instar fed on the cottonseed meal-based diet instead of wheat germ meal based diet.On the same diet,84.00%±4.00%,17.24 mg±0.03 mg,and 7.76d±0.06 d were recorded as pupae formation,pupal weight,and pupal duration,respectively.Adult emergence,76.00%±1.00%was recorded from pupae collected from larvae raised on cottonseed meal-based diet.These male and female moths lived for 40.25d±0.10 d,and 44.34d±0.11 d,respectively.Females deposited 21.28±0.04 eggs per day with the viability of 65.78%±0.14%.The larval mortal-ity at the fourth instar was 37.20%±1.36%and malformed pupation of 12.00%±1.41%was recorded.Replacement of wheat germ meal with that of local meals(cottonseed and okra seed)in the standard laboratory diet has saved 463.80 to 467.10 PKR with 1.62 to 1.63 cost economic returns,respectively.Conclusion This research is of novel nature as it provides a concise and workable system for the economic and suc-cessful rearing of P.gossypiella under laboratory conditions.

The Preliminary Study on Artificial Propagation and Fry Rearing of Misgurnus anguillicaudatus

[Objective] The aim was to seek the optimal choice of hormones,induced temperature,and initial feed for cultivating loach.[Method] Different hormones were injected to Ioaches for artificial reproduction in water at different temperatures.During cultivation,varied initial feeds were put in to explore the optimal choice of hormones,temperature and initial feed.[Result] According to the test,fecundity of female loach is directly proportional to gonad maturity,namely,the higher gonad maturity,the more fecundity.For example,for a female loach whose maturity coefficient was 24％,absolute and relative fecundity rates were 62 142 and 990.In contrast,for a female whose maturity coefficient was 9％,the rates were 18 207 and 367,respectively.The induced effect differs upon hormones and the test demonstrated that LRH-A2 is better in improving fertility rate compared with HCG.For example,the fertility rate in the group with HCG was 78.84 and in the group with LRH-A2 was 83.04％.It is notable that the mixture of the two at a certain ratio would enhance induced effect and the fertility rate can be as high as 89.17％.With temperature in a certain range,the higher temperature,the better induced effect.The test indicated that water temperature at （30±0.5） ℃ is an optimal one and the effect horizon is 6-8 h.In group 4,induced rate was 93.33％ and the fertility rate was 89.26％.The research indicated that the survival rate was the highest if wheel animalcule,dominated by Brachionus calyciflorus and Brachionus angularis,was taken as an initial feed,followed by artemia nauplii and corpuscule.In addition,loach fry in the group with yolk and wheel animalcule grew about 1.21 times than the group with only yolk,1.04 times than the group with only fairy shrimp,and 1.1 times than the group with fairy shrimp.[Conclusion] The research provides scientific references for scale loach farming.

Optimization of Artificial Rearing Methods for Plutella xylostella L.(Plutellidae)and Its Susceptibility to Five Types of Insecticides

[Objective] The research aimed to optimize laboratory artificial rearing methods for Plutella xylostella L. and to select out effective insecticides against this pest species. [Method] Brassica chinensis seedlings were cultivated in the laboratory at （25±1）℃, 60-75% RH, and a photoperiod of 14：10 （L：D） h. The green blow molding papers were used to collect eggs, and Brassica oleracea seedlings were cultivated to breed Plutella xylostella L. until the insects were ready for use. Mean-while, the susceptibility of 3rd instar larvae of Plutella xylostella L. to five types of insecticides was tested by leaf-dipping method. [Result] Plutella xylostella L. larvae were found well-grown and uniform in developmental stages with average pupa weight of 5.4 mg, pupa emergence percentage of 94.0 % and egg number of 135.1 per female. The LCso values of 3rd instar Plutella xylostella L. larvae against 200 g/L chlorantraniliprole SC, 20% flubendiamide WG, 150 g/L indoxacarb EC, 200 g/L tebufenozide SC and 1.8% abamectin EC, were 0.152, 0.223, 1.151, 93.340 and 0.128 mg/L, respectively. [Conclusion] This rearing method is easy to be implemented and of great practicality, suitable for mass propagation of P. xylostella L. Abamectin, chlorantraniliprole and flubendiamide showed high insecticidal activities, so these three insecticides can be used alternately for the field prevention and control of Plutella xylostella L.

Current research progresses on calf rearing and nutrition in China

Calves are the reserve forces for dairy cattle. Scientific rearing strategy of calves is the basis of efficient cattle breeding. However, many problems exist in current rearing systems of calves and restrict the sustainable development of dairy cattle in China. The absence of basic research is the most highlighted problem among them. Recent researches on growth performance, nutrient digestibility, blood biochemical indices and rumen development in calves were summarized in this paper. Additionally, the optimal levels of energy and protein in milk replacer and starter diets for calves were indicated, and limiting amino acids for calves fed different diets were discussed. A variety of additives, such as acidifiers, probiotics and polysaccharides, are regarded as promising alternatives to antibiotics to reduce disease in calves. Dietary supplementations of these additives have positive effects on growth and health of calves. However, studies on the nutrition of vitamins and minerals in calves have been seldom done, and deserve our further researches. To sum up, the postnatal period is one of the most critical “windows” for rumen manipulation and epigenetic regulation. Any changes from environments, especially early nutrition, may produce long-term effects on growth, health and milk yields in adult cattle.

Structure optimal design research on backfill hydraulic support

Backfill hydraulic support is the key equipment in achieving coal mining and solid backfilling simultaneously in solid backfill mining technology.Based on the summary and analysis of main types,basic structural properties and filed application of backfill hydraulic support,this work has firstly proposed the basic principle of backfill hydraulic support optimization design and provided the method of optimal design of key structural components,like four-bar linkage,rear canopy and tamping structure;the method is further elaborated as changing hinging position of upper bar to optimize four-bar linkage,by lengthening or shortening the rear canopy to optimize length ratio of canopy;and by changing length and hinging position of tamping structure as well as suspension height of backfill scrape conveyor to realize optimization of tamping structure.On this basis,the process of optimal design of backfill hydraulic support is built.The optimal design case of ZC5200/14.5/30 six columns-four bar linkage used in 7203 W workface of Zhaizhen Coal Mine shows that the backfill properties like horizontal roof gap,vertical horizontal gap,tamping angle and tamping head gap are improved obviously through optimizing four-bar linkage,canopy length and tamping structure according to the optimal design method proposed in this work.

Are parental rearing patterns and learning burnout correlated with empathy amongst undergraduate nursing students?

Objective:Empathy can help establish harmonious nurse-patient relationships.We aimed to assess the status of empathy,and explore the relationship between learning burnout,parental rearing patterns and empathy amongst nursing students.Method:A questionnaire survey that employed the Learning Burnout Scale,the Short-Form Egna Minnenav Barndoms Uppfostran(s-EMBU)and the Jefferson Scale of Empathy was conducted amongst 562 nursing students.The data were analysed on the basis of descriptive statistic and correlation analysis was used.Results:Empathy is negatively correlated with learning burnout,parental rejection and overprotection and showed no positive correlation with parental emotional warmth.Conclusions:Educators should pay attention to nursing students'feelings and learning burnout status and take positive measures to improve the empathy level of the students.Positive parental rearing patterns also help cultivate empathy.

Long term effects of artificial rearing before weaning on the growth performance, ruminal microbiota and fermentation of fattening lambs

Early life intervention is important to shape the gut microbiome profiles of adult animals due to the tremendous alteration of diet components. Nevertheless, there is still no unified understanding about its long-term effects in lambs. In this study, sixty 20-day-old lambs were assigned into ewe-rearing(ER) and artificial-rearing(AR) treatments to evaluate the effects of AR strategy on ruminal microbiota, fermentation, and morphology of pre-weaning lambs(from 20 to 60 days of age) and its long-term effects in the fattening stage(from 61 to 180 days of age). During the pre-weaning stage, ER lambs were breastfed and supplemented starter, while AR lambs were artificially fed with milk replacer and starter. During the fattening stage, all lambs in both treatments were fed with the same fattening diets. At 60, 120 and 180 days of age, 6 lambs from each group were slaughtered to collect rumen content and tissue samples. Compared with ER lambs, the dry matter feed intakes of AR lambs increased(P<0.05) from 20 to 180 days of age, companying an increased average daily gain(ADG) from 61 to 120 days of age(P<0.05) and from 121 to 180 days of age(0.05<P<0.1). Although there was no difference in short-chain fatty acid(SCFA, including acetate, propionate, and butyrate) between treatments before weaning(P>0.05), it was higher(P<0.05) in AR lambs compared with ER lambs at the fattening stage. The rumen keratin layer of AR lambs was thinner(P<0.05) than that of ER lambs. Along with lamb growth from 60 to 180 days of age, the differences in rumen bacterial diversity between AR and ER treatments grew more distinct(P<0.05). Compared with ER lambs, AR lambs increased(P<0.05) rumen bacteria abundance, such as phylum Spirochaetes and genus Treponema at 60 days of age, phylum Actinobacteria and genus Succiniclasticum at 120 days of age, and phylum Proteobacteria at 180 days of age, but decreased genus Selenomonas from 60 to 180 days of age, and Anaerovibrio at 180 days of age. In summary, the early interventions before weaning could improve dry matter feed intake of lambs, which triggered robust rumen development and produced positive long-term effects on rumen fermentation and noticeable weight gain of fattening lambs. It suggests that the artificial rearing strategy is effective in improving rumen fermentation and microbial maturity of intensive fattening lambs.

Community diversity of bacteria in digestive tract of mud snail (Bullacta exarata Philippi) and its rearing shoal

The bacterial flora in the digestive tract of B. exarata Philippi and its rearing shoal were investigated, respectively. A total of 107 strains of heterotrophic bacteria, isolated from crop, stomach and intestine, mainly belong to genera Photobacterium, Bacillus, Pseudomonas and Vibrio. Varieties of bacteria in crop were significantly more than that in stomach and in intestine. A total of 173 strains of bacteria were isolated from the rearing shoal, belonging to 13 genera. The 5 predominant genera are Photobacterium, Bacillus, Pseudomonas, Vibrio and some genera of Enterobacteriaceae. The number of heterotrophic bacteria and Vibrio in rearing shoal changed in line with the alteration of the temperature, and were significantly affected by the use of pesticide.

Mass rearing of Lucilia sericata Meigen (Diptera:Calliphoridae)

Objective:To carry out an experimental study with the main objective of mass rearing of sheep flies(Lucilia sericata).Methods:Hand collection and beef- or cattle liver-baited net traps were used for field fly sampling from April,2010 to November,2010.The samples collected from different places were placed in properly labeled tubes and sent to the Entomology Laboratory. Since maggot identification is important in inducing mortality,they were kept under insectary condition to develop to adult stage and identified using systematic keys.Results:A total of 218 flies were collected in three rounds of sampling from the field of Tehran and Karaj Counties.In the first generation,433 flies including 135(31.17%) male,and 298(68.82%) female were yielded. The female/male of parent ratio was calculated as 1.72 in Tehran and in Karaj areas,whereas it was 2,20%and 1.81%,respectively in Fl and F2 generations,respectively.Conclusions:During this study,the mass rearing of sheep blow fly has been established at the School of Public Health, Tehran University of Medical Sciences and can be used for producing flies for maggot therapy.

Numerical study of mono-crystalline silicon solar cells with passivated emitter and rear contact configuration for the efficiency beyond 24% based on mass production technology

Mono-crystalline silicon solar cells with a passivated emitter rear contact(PERC)configuration have attracted extensive attention from both industry and scientific communities.A record efficiency of 24.06%on p-type silicon wafer and mass production efficiency around 22%have been demonstrated,mainly due to its superior rear side passivation.In this work,the PERC solar cells with a p-type silicon wafer were numerically studied in terms of the surface passivation,quality of silicon wafer and metal electrodes.A rational way to achieve a 24%mass-production efficiency was proposed.Free energy loss analyses were adopted to address the loss sources with respect to the limit efficiency of 29%,which provides a guideline for the design and manufacture of a high-efficiency PERC solar cell.

Numerical investigation into effect of rear barrier pillar on stress distribution around a longwall face

Numerical investigation was performed to examine the effect of rear barrier pillar on stress distribution around a longwall face. Salamon theoretical formula was used to calculate the parameters of the caving zone, which was later assigned to double yield constitutive model in FLAC3 D. Numerical results demonstrate that high stress concentration zone exists above the region where the second open-off cut intersects with the rear barrier pillar due to stress transfer and plastic zone expansion. It is also found that the maximum vertical stresses with varied distance to the seam floor are all within the projective plane of the rear barrier pillar and their positions concentrate on the barrier pillar adjacent to the connection corner of the second open-off cut. In addition, position of the maximum vertical stresses abruptly transfer from the connection corner adjacent to former panel to that adjacent to current panel along the panel direction.

Damage characteristics of laser plasma shock wave on rear surface of fused silica glass

The damage to the rear surface of fused silica under the action of high power laser is more severe than that incurred by the front surface,which hinders the improvement in the energy of the high power laser device.For optical components,the ionization breakdown by laser is a main factor causing damage,particularly with laser plasma shock waves,which can cause large-scale fracture damage in fused silica.In this study,the damage morphology is experimentally investigated,and the characteristics of the damage point are obtained.In the theoretical study,the coupling and transmission of the shock wave in glass are investigated based on the finite element method.Thus,both the magnitude and the orientation of stress are obtained.The damage mechanism of the glass can be explained based on the fracture characteristics of glass under different stresses and also on the variation of the damage zone’s Raman spectrum.In addition,the influence of the glass thickness on the damage morphology is investigated.The results obtained in this study can be used as a reference in understanding the characteristics and mechanism of damage characteristics induced by laser plasma shock waves.

A Method for Mass-rearing Aphidius gifuensis(Hymenoptera: Aphidiidae)

[Objective] This study presents a method for mass rearing of Aphidius gifuensis, a dominant endoparasitoid of Myzus persicae on tobacco in Southwest China. [Method] The tobacco cultivar Honghuadajinyuan(Nicotiana tabacum) was used as the host plant and M. persicae was the host insect. In a greenhouse, tobacco seedlings were reared in plastic trays. The seedlings at three-true-leaf stage were inoculated with two to three aphids per plant using aphid source with a parasitism rate of 47% ±3.9%. [Result] By this inoculation method, the aphids and parasites were simultaneously inoculated on host plants. After approximately 25 d of rearing, we were able to produce 82.5±5.17 aphid mummies per tobacco seedling. A total of 445 500 aphid mummies were produced in one greenhouse(36 rearing trays per greenhouse) during an approximately 50-day rearing period. The emergence rate was 93.4% ±2.76%, and 54% of the mummies were females. [Conclusion] The demonstrated technological feasibility of using tobacco seedlings for the mass rearing of A. gifuensis increases the potential for the biological control of M. persicae.

Consequences of early adverse rearing experience(EARE) on development： insights from non-human primate studies

Early rearing experiences are important in one＇s whole life, whereas early adverse rearing experience（EARE） is usually related to various physical and mental disorders in later life. Although there were many studies on human and animals, regarding the effect of EARE on brain development, neuroendocrine systems, as well as the consequential mental disorders and behavioral abnormalities, the underlying mechanisms remain unclear. Due to the close genetic relationship and similarity in social organizations with humans, non-human primate（NHP） studies were performed for over 60 years. Various EARE models were developed to disrupt the early normal interactions between infants and mothers or peers. Those studies provided important insights of EARE induced effects on the physiological and behavioral systems of NHPs across life span, such as social behaviors（including disturbance behavior, social deficiency, sexual behavior, etc）, learning and memory ability, brain structural and functional developments（including influences on neurons and glia cells, neuroendocrine systems, e.g., hypothalamic-pituitary-adrenal（HPA） axis, etc）. In this review, the effects of EARE and the underlying epigenetic mechanisms were comprehensively summarized and the possibility of rehabilitation was discussed.