Determining the Onset and Strength of Unforced Wave Breaking in A Numerical Wave Tank

A numerical wave tank is used to investigate the onset and strength of unforced wave breaking, and the waves have three types of initial spectra： constant amplitude spectrum, constant steepness spectrum and Pierson-Moscowitz spectrum. Numerical tests are performed to validate the model results. Then, the onset of wave breaking is discussed with geometric, kinematic, and dynamic breaking criteria. The strength of wave breaking, which is always characterized by the fractional energy loss and breaking strength coefficient, is studied for different spectra. The results show how the energy growth rate is better than the initial wave steepness on estimating the fractional energy losses as well as breaking strength coefficient.

TENSILE-SHEAR STRENGTH AND BREAKING MORPHOLOGY FOR VIBRATION DAMPING LAMINATED STEEL SHEET

The phenolic resin-chloroprene nthher was used for sandwich in manufueturing the vibra-tion damping laminated steel sheet (also calied laminated sheet), Il is a metal matrix com-posite. The tensie-shear tests have been conducted over a range of temperatures from 20C to 150C and at the strain rates from 1.67× 10 ^(5) to 1.67× 10^(-2)s^(-1). The results show that test temperature will significaiilly affect the tensile shear strength of laminated sheet. and a minimal strength and a minimal activation energy occur near 80C . The tensile-shear breaking morphology of laminated sheet varies with strain rate and test temjteralurc.

Investigation on the Relationship between Specimen Width and Breaking Strength of Geotextile

The tensile properties of geotextile are analyzed with the boundary element method, with special emphasis put on the influence of specimen width on geotextile breaking strength. The theoretical and experimental results showed that narrow specimen would underestimate the tensile strength of the geotextile. During testing procedure, the lateral contraction of the specimen is the main reason that causes the breaking strength to be on the lower side. The theoretical results also indicate that the breaking strength of the geotextile would arrive at a fixed value when the specimen width is increased to a certain extent.

ON THE RELATIONSHIP BETWEEN TENSILE STRENGTH,BREAKING ELONCATION,CRYSTALLINITY AND ORIENTAHON OF SILK

In this paper,the relation between the tensile strength,breaking elongationand the Crystallinity,Orientation of silk was studied,which obtalned from thecocoons with different silk worm races,sexes,cocooning conditions.The Crystallinity and degree of Crystal Orientation of fibroin were determinedby the X-ray diffraction.and the birefringence of fibroin was measured withInterference microscope.The research showed that the dependence of strength and elongation of rawsilk on Its crystailinity was not so closed.Although there was linear correlation ofstrength with the birefringence and the degree of crystal orientation of fibroin.But the correlation coefficient of the former was larger than the latter.Therefore,adopting birefringence method which would reflected the degree of orlentation ofboth the amorphous and crystalline region of fibroln was suitable for consideringthe strength.The correlation coefficients of strength and elongation withbirefringence were 0.96 and 0.77 respectively.The latter one was

Comprehensive evaluation of chemical breakers for multistage network ultra-high strength gel

Polymer gels have been accepted as a useful tool to address many sealing operations such as drilling and completion,well stimulation,wellbore integrity,water and gas shutoff,etc.Previously,we developed an ultra-high strength gel(USGel)for medium to ultra-low temperature reservoirs.However,the removal of USGel is a difficult problem for most temporary plugging operations.This paper first provides new insights into the mechanism of USGel,where multistage network structure and physical entanglement are the main reasons for USGel possessing ultra-high strength.Then the effects of acid breakers,encapsulated breakers,and oxidation breakers(including H_(2)O_(2),Na_(2)S_(2)O_(8),Ca(ClO)_(2),H_(2)O_(2)+NaOH,Na_(2)S_(2)O_(8)+NaOH,and Ca(ClO)_(2)+NaOH)were evaluated.The effects of component concentration and temperature on the breaking solution were studied,and the corrosion performance,physical simulation and formation damage tests of the breaking solution were carried out.The final formulation of 2%-4%NaOH+4.5%-6%H_(2)O_(2) breaking solution was determined,which can make USGel completely turn into water at 35e105C.The combinations of“acid t breaking solution”,“acid+encapsulated breaker”and“encapsulated breaker+breaking solution”were evaluated for breaking effect.The acid gradually reduced the volume of USGel,which increased the contact area between breaking solution and USGel,and the effect of“4%acid+breaking solution”was 23 times higher than that of breaking solution alone at 35C.However,the acid significantly reduced the strength of USGel.This paper provides new insights into the breaking of high-strength gels with complex network structures.

The Effect of Bridging Liquid Surface Tension and Specific Surface Area on Strength Factor of Coal Agglomerates

The aim of this research is to determine the effect of bridging liquid surface tension and specific surface area on strength factor of coal agglomerates. The production of coal agglomerates of the range 15-27.51 mm was achieved. The crushing strength of the agglomerates was determined for good handling of fine （coal-liquid mixture） to improve fugitive dust control, decrease in transportation losses, reduce risk of coal freezing, lower risk of spontaneous combustion, etc. in iron and steel industries, railway corporations and coal corporations. Kerosene （paraffin oil） was used as a binder and the agglomerated coal oil mixture was pelletized using balling technique （disc）. Mechanical and physical tests like compressive strength test, etc. were carried out. The relationship between the bridging liquid surface tension and specific surface area on strength factor of coal agglomerates showed that there is considerable variation in these parameters in the coal powder systems.

Breeding Resilience:Exploring Lodging Resistance Mechanisms in Rice

Lodging is more than just plants falling over;it incurs significant economic losses for farmers leading to a decrease in both yield and quality of the final produce.Human management practices,such as dense sowing,excessive nitrogen fertilizer applications,inappropriate sowing dates,and upland rice cultivation,exacerbate the risk of lodging in rice.While breeders have developed high-yielding rice varieties utilizing the sd1 gene,relying solely on this gene is insufficient to enhance lodging resistance.Identifying the traits that contribute to lodging resistance is crucial.Key factors include biochemical,anatomical,and morphological traits,such as the levels of lignin,cellulose,hemicellulose,silicon,and potassium,along with the number and area of vascular bundles and the thickness,diameter,and length of the culm.Moreover,markers associated with lodging-related genes,like SCM2,SCM3,SCM4,and prl4,can be utilized effectively in marker-assisted backcrossing to develop rice varieties with desirable culm traits.This literature review aims to aid rice breeders in addressing the issue of lodging by examining traits that influence lodging resistance,developing phenotyping strategies for these traits,identifying suitable instrumentation,exploring methods for screening lodging-resistant plants,understanding the mathematical relationships involved,and considering molecular breeding aspects for pyramiding genes related to lodging.

试论Breaking训练中力量训练的重要性

Breaking诞生在二十世纪六十年代末,是美国黑人城市贫民的舞蹈,Breaking在许多青少年和帮派成员中非常流行,而breaking就是从街头开始的。通常,敌对团体中最好的舞者常用Battle(斗舞)的方式进行来展示舞蹈的智慧,而不是采用武力。在Battle(斗舞)中舞者需要表达自己的态度,通过日常各种力量训练使肢体力量的动律足以表达自身的态度。本文在了解Breaking的含义、起源、发展的基础之上,分析整理了有关于力量训练的内容,并以此为基础探讨了Breaking的力量训练内容,探析力量训练在Breaking舞蹈课堂中的现状,并分析力量训练对Breaking的重要性,从而体现力量训练对于舞蹈而言的至关重要性。

预切缝辅助TBM滚刀破岩贯入荷载演化规律

基于全断面隧道掘进机(Tunnel Boring Machine,TBM)滚刀贯入室内模型试验,研究了3种不同破岩模式(完整岩样破岩、同轨迹破岩和异轨迹破岩)在不同围压条件下高强度花岗岩样贯入荷载演化特征,重点揭示贯入荷载-贯入度特征曲线、峰值荷载、最大跌落幅值变化规律,获取不同破岩模式在不同围压条件下TBM滚刀受力特性。结果表明:1)高围压组贯入荷载-贯入度特征曲线较低围压组先跌落,跌落幅度较小,但其对应的贯入荷载并非峰值荷载,而低围压组初次跌落荷载为峰值荷载,且跌落幅值较大;2)在中高围压10~15 MPa时,峰值荷载及贯入荷载最大跌落幅值均最小,表明此围压范围较利于TBM的掘进;3)低围压条件下选用异轨迹破岩模式较同轨迹破岩模式能更有效地降低TBM滚刀贯入荷载,但同轨迹破岩模式的岩样发生楔裂破坏,其最大跌落幅值最小,更能减少刀具所受冲击荷载,减少刀具磨损。

基于正交试验的纱线断裂时间与强力的回归分析

通过三因素三水平的正交试验,利用极差法和显著性水平分析法得出:隔距、拉伸速度、预加张力这三个因素对单纱断裂强力、断裂伸长率、断裂时间的影响不明显;隔距、预加张力对单纱断裂强力、断裂伸长率、断裂时间的影响为不显著;拉伸速度对单纱断裂强力、断裂伸长率的影响为不显著,对断裂时间的影响为显著。通过回归分析,断裂时间与断裂强力两者之间存在明显的函数关系,建立断裂时间与断裂强力的回归方程,R^(2)值接近1,该方程可以准确有效地模拟断裂时间与断裂强力的函数关系。断裂时间是单纱断裂强力的一个重要表征值,建议在以后的标准更新中将其纳为考核指标,为纱线的使用者提供参考依据。

二维碳纤维织物/酚醛-丁腈橡胶的性能研究

分别以3K聚丙烯腈基五枚缎纹碳布、聚丙烯腈基碳纤维罗纹织物和聚丙烯腈基碳纤维三维编织物作为增强材料制备碳纤维织物/酚醛-丁腈橡胶材料,研究了碳纤维织物/酚醛-丁腈橡胶的拉伸强度、断裂伸长率、抗烧蚀性能和增强材料形态对预浸织物浸渍效果的影响,并与常用的短切黏胶基碳纤维/酚醛-丁腈橡胶性能进行了对比。研究结果表明:聚丙烯腈基碳纤维三维编织物/酚醛-丁腈橡胶材料的拉伸强度为29.1 MPa,断裂伸长率达到18.06%,氧-乙炔烧蚀率为0.002 mm/s,综合性能最优;聚丙烯腈基碳纤维罗纹织物/酚醛-丁腈橡胶材料的拉伸强度为13.2 MPa,断裂伸长率达到了16%,氧-乙炔烧蚀率为0.007 mm/s,综合性能仅次于聚丙烯腈基碳纤维三维编织物/酚醛-丁腈橡胶,生产成本较聚丙烯腈基碳纤维三维编织物/酚醛-丁腈橡胶大幅度下降;两种材料的拉伸强度与短切黏胶基碳纤维/酚醛-丁腈橡胶相当,韧性和抗冲刷性能具有显著优势。

Key indicators affecting maize stalk lodging resistance of different growth periods under different sowing dates

The accurate evaluation of maize stalk lodging resistance in different growth periods enables timely management of lodging risks and ensures stable and high maize yields.Here,we established five diferent sowing dates to create diferent conditions for maize growth.We evaluated the effects of the different growth conditions on lodging resistance by determining stalk morphology,moisture content,mechanical strength and dry matter,and the relationship between stalk breaking force and these indicators during the silking stage(R1),milk stage(R3),physiological maturity stage(R6),and 20 days after R6.Plant height at R1 positively affected stalk breaking force.At R3,the cofficient of ear height and the dry weight per unit length of basal internodes were key indicators of stalk lodging resistance.At R6,the key indicators were the coefficient of the center of gravity height and plant fresh weight.After R6,the key indicator was the coefficient of the center of gravity height.The crushing strength of the fourth internode correlated significanty and positively with the stalk breaking force from R1 to R6,which indicates that crushing strength is a reliable indicator of stalk mechanical strength.These results suggest that high stalk strength and low ear height beneft lodging resistance prior to R6.During and after R6,the cofficient of the center of gravity height and the mechanical strength of basal internodes can be used to evaluate plant lodging resistance and the appropriate time for harvesting in fields with a high lodging risk.

Wound healing activity of aqueous extract of Crotalaria verrucosa in Wistar albino rats

Objective:To evaluate the wound healing effect of aqueous extract of Crotalaria verrucosa(C. verrucosa) in rats.Methods:Three wound models including incision,excision and dead space wounds were used in this study.The parameters studied were breaking strength in incision models,granulation tissue dry weight,breaking strength and hydroxyproline content in dead space wounds,percentage of wound contraction and period of epithelialization in excision wound model.Results:Two doses of the extract with and without dexamethasone showed significant increases in mean hydroxyproline,total protein content and dry weight of granulation tissue but it was higher with dose 800 mg/kg comparing with the control.The dexamethasone treated group showed a significant(P【0.001) reduction in the wound breaking strength when compared to control group in incision type of wound model.Coadministration of C.verrucosa with dexamethasone significantly(P【0.001) increased the breaking strength compared to the dexamethasone treated only group.In excision wound model,the percentage of the wound contraction was significantly(P【0.01) increased by two doses of test extract on all the days except the lower dose which exhibited only on 12th,16th days of drug treatment and it also reversed the dexamethasone suppressed wound contraction.It significantly(P【0.001) reduced the time required for epithelialization and reversed the epithelialization delaying effect of dexamethasone (P【0.001).Conclusions:C.verrucosa was found to possess significant wound healing property. This was evident by decrease in the period of epithelialization,increase in the rate of wound contraction,skin breaking strength,and granulation tissue dry weight content.Hence C. verrucosa could be a good wound healing agent.

Primer containing dimethylaminododecyl methacrylate kills bacteria impregnated in human dentin blocks

Antibacterial dimethylaminododecyl methacrylate （DMADDM） was recently synthesized. The objectives of this study were to： （1） investigate antibacterial activity of DMADDM-containing primer on Streptococcus mutans impregnated into dentin blocks for the first time, and （2） compare the antibacterial efficacy of DMADDM with a previous quaternary ammonium dimethacrylate （QADM）. Scotchbond Multi-Purpose （SBMP） bonding agent was used. DMADDM and QADM were mixed into SBMP primer. Six primers were tested： SBMP control primer P, P＋2.5% DMADDM, P＋5% DMADDM, P＋7.5% DMADDM, P＋10% DMADDM, and P＋10% QADM. S. mutans were impregnated into human dentin blocks, and each primer was applied to dentin to test its ability to kill bacteria in dentinal tubules. Bacteria in dentin were collected via a sonication method, and the colony-forming units （CFU） and inhibition zones were measured. The bacterial inhibition zone of P＋10% DMADDM was 10 times that of control primer （P〈0.05）. CFU in dentin with P＋10% DMADDM was reduced by three orders of magnitude, compared with control. DMADDM had a much stronger antibacterial effect than QADM, and antibacterial efficacy increased with increasing DMADDM concentration. Dentin shear bond strengths were similar among all groups （P〉0.1）. In conclusion, antibacterial DMADDM-containing primer was validated to kill bacteria inside dentin blocks, possessing a much stronger antibacterial potency than the previous QADM. DMADDM-containing bonding agent was effective in eradicating bacteria in dentin, and its efficacy was directly proportional to DMADDM mass fraction. Therefore, DMADDM may be promisine for use in bonding agents as well as in other restorative and oreventive materials to inhibit bacteria.

Pharmacological interventions for improved colonic anastomotic healing:A meta-analysis

AIM: To identify pharmaceuticals for the prophylaxis of anastomotic leakage (AL), we systematically reviewed studies on anastomosis repair after colorectal surgery.

KNOT STRENGTH OF INDUSTRIAL TEXTILE FIBRES

In this paper, the knot strengths of the seven strands which were made of polyethleneterephthalate(PET), nylon 6, polyvinyl formal fibre, polypropylene and polyethylene with differentspecification used for industrial purposes were tested and discussed. The results of experimentshow: the knot strength loss does not only depend on the breaking elongation and the diameter ofsample, but also on the shape of the load-extension curve and twist factor of sample and other fac-tors; the range of the knot strength loss and the breaking energy loss vary in a wide range, in thepresent case. the former is from 2.7% to 58.14% and the latter from 16.36% to 78.76%. Thestrength loss of the polypropylene filament is the least among the samples investigated.

Therapeutic improvement of colonic anastomotic healing under complicated conditions: A systematic review

AIM: To identify therapeutic agents for the prophylaxis of gastrointestinal anastomotic leakage(AL) under complicated conditions. METHODS: The Pub Med and EMBASE databases were searched for English articles published between January 1975 and September 2014. Studies with the primary purpose of improving anastomotic healing in the colon or rectum under complicated preoperative and/or intraoperative conditions were included. We excluded studies investigating the adverse effects or risk assessment of an active intervention. Furthermore, investigations of biophysical materials, sealants, electrical stimulation and nutrients were excluded. The primary study outcome was biomechanical anastomotic strength or AL. The meta-analysis focused on therapeutic agents that were investigated in one animal model using the same outcome by at least three independent research groups. RESULTS: The 65 studies included were divided into 7 different complicated animal models: Bowel ischemia, ischemia/reperfusion, bowel obstruction, obstructive jaundice, peritonitis, chemotherapy and radiotherapy. In total, 48 different therapeutic compounds were examined. The majority of investigated agents(65%) were reported as beneficial for anastomotic healing. Twelve of the agents(25%) were tested more than once in the same model, whereas 13(27%) of the agents were tested in two or more models of complicated healing. Two therapeutic agents met our inclusion criteria for the meta-analysis. Postoperative hyperbaric oxygen therapy significantly increased anastomoticbursting pressure in ischemic colon anastomoses by a mean of 28 mm Hg(95%CI: 17 to 39 mm Hg, P < 0.00001). Granulocyte macrophage-colony stimulating factor failed to show a significant increase in anastomotic bursting pressure(95%CI:-20 to 21 mmH g, P = 0.97) vs controls in experimental chemotherapeutic models. CONCLUSION: This systematic review identified potential therapeutic agents, but more studies are needed before concluding that any of these are useful for AL prophylaxis.

Wound healing activity of Abroma augusta in Wistar rats

Objective:The study was undertaken to evaluate the wound healing profile of alcoholic extract of Abroma augusta and its effect on dexamethasone suppressed wound healing in Wistar rats.Methods:An alcoholic extract of Abroma augusta was prepared.Three models were used - incision,excision and dead space wound models. Four groups of animals were used for each model.They were administered 2%gum acacia(orally),alcoholic extract of Abroma augusta(orally),dexamethasone(intramuscularly) and combination of Abroma augusta(orally) with dexamethasone(intramuscularly) respectively.The parameters studied included breaking strength of incision wound,period of epithelization and wound contraction rate in the excision wound,breaking strength,dry weight and hydroxyproline content of granulation tissue in dead space wound.Results:The breaking strength of incision wound of Abroma augusta treated group was significantly increased(P <0.001 ) while that of dexamethasone treated animals was significantly decreased(P<0.001) as compared to control. Coadministration of dexamethasone and Abroma augusta significantly reversed the dexamethasone suppressed wound healing in incision wound model(P< 0.001 ).Animals treated with both dexamethasone and Abroma augusta also showed significant(P <0.004) increase in the breaking strength of granulation tissue in the dead space wound and a significant(P <0.011) reduction in the period of epithelization in the excision wound as compared to rats treated with dexamethasone alone.The rate of wound contraction was not significantly altered in any of the groups.Conclusion:The alcoholic extract of Abroma augusta was found to reverse dexamethasone suppressed wound healing.

Processing Methods and Properties of Two Composite Geotextiles

In order to develope new composite geotextiles with good comprehensive properties,the needle-punched composite geotextiles and adhesive bonded composite geotextiles were made in the factory and laboratory separately.The two processing methods were studied and the mechanical and hydraulic properties of the two kinds of products were tested and compared.The experimental resultsshow that the breaking strength of needle-punched composite geotextiles is much lower than that of adhesive bonded composite geotextiles and the latter also have better hydraulic properties than the former which used

Optimization of Multigrain Premix for High Protein and Dietary Fibre Biscuits Using Response Surface Methodology (RSM)

In order to improve the nutritional quality of biscuits, a multigrain premix (MGP) was developed by using whole barley, sorghum, chickpea, pea and defatted soya flour, each at 20% level. The developed MGP had 26.28% protein, 10.13% insoluble dietary fiber and 7.38% soluble dietary fiber. The experiment was designed to optimise the MGP and wheat flour concentration for the development of multigrain biscuits with high protein, dietary fibre and to maximize the acceptability by the application of central composite rotatable design (CCRD) of Response Surface Methodology (RSM). The levels of incorporation of MGP and wheat flour were taken as variables whereas protein, soluble, insoluble fibers, biscuit dough hardness, breaking strength and overall acceptability (OAA) as responses. The optimum level of MGP and wheat flour obtained using numerical optimization was found to be 40 g and 60 g respectively. The biscuits prepared using these had 16.61% protein, 2.57% soluble fibre, and 6.67% insoluble fibre which is significantly (p ≤ 0.05) higher than control biscuit.