不同桩核系统修复上颌双尖牙腭尖缺失的抗力性研究

目的:比较不同桩核系统修复上颌双尖牙腭尖缺失后牙体的抗折强度。方法:将40颗因正畸拔除的上颌第一双尖牙,切除腭侧牙冠并常规根管治疗后随机分为A、B、C、D4组,分别给予铸造镍铬合金桩核+金属全冠,铸造金合金桩核+金属全冠,Popo玻璃纤维桩+树脂核+金属全冠,Bisco石英纤维桩+树脂核+金属全冠修复。应用万能应力测试机进行抗力性检测,记录试件破坏时施力的大小,观察试件破坏的形式及部位。结果:方差分析显示A组抗折强度最大,A组与B组、C组、D组抗折强度的差异有显著性(P<0.05或P<0.01)。B组、C组、D组间抗折强度的差异没有显著性(P>0.05)。A、B组离体牙破坏性折断明显多于C、D两组。结论:金属桩增强了牙齿的抗折能力,但纤维桩更利于保护牙根。

不同桩核系统修复喇叭状根管的抗力性研究

目的比较不同桩核系统修复喇叭状根管的抗折强度。方法将36颗因正畸拔除的下颌双尖牙,沿釉牙本质界冠方2mm水平切除牙冠,常规根管治疗后将根管上端敞开预备成喇叭状,再随机分为A、B、C三组,A组给予铸造镍铬合金桩核+金属全冠;B组给予Popo玻璃纤维桩+树脂核+金属全冠;C组给予Macrolock石英纤维桩+树脂核+金属全冠修复。应用万能应力测试机进行抗力性检测,记录试件破坏时施力的大小,观察试件破坏的形式及部位。结果A组与B组、C组的离体牙桩核冠修复后牙体析断时的最大载荷分别为(602.80±75.86)N、(383.86±48.47)N、(426.39±55.28)N。A组与B组、C组抗折强度比较,差异均有统计学意义(t分别=8.55、6.65,P均<0.05)。A组破坏性折断明显多于B组和C组,差异有统计学意义(χ2分别=13.59、10.67,P均<0.05)。B组与C组的抗折强度、破坏性折断例数比较,差异无统计学意义(t=2.01,χ2=0.38,P均>0.05)。结论采用不同桩核系统修复,喇叭状根管的抗折强度不同。金属桩具有较强的抗折能力,但纤维桩的抗折能力已满足日常口腔咀嚼功能的需要,且纤维桩更利于保护牙根。Popo玻璃纤维和Macrolock石英纤维桩的抗折强度没有明显差异。

根管预备中镍钛器械的应力分布及牙根的抗力性改变

选取2012年5月～2013年5月我院进行根管治疗的患者46例,随机分为研究组与对照组,研究组填充物选取氧化锌丁香油糊剂与牙胶尖,对照组填充物选取环氧树脂糊剂与牙胶尖,将两组患者牙根抗力性的改变情况进行对比分析。结果经治疗后,两组的治疗成功率、失败率及发生牙冠纵裂率对比均无显著性差异(P>0.05)。临床针对牙病患者的根管治疗方式,采取不同的充填方法及根管预备,对患者牙根抗力性无明显影响,且临床疗效无显著差异,但选用根管治疗方式对患者牙病进行治疗时,对患者牙根的整体抗力性可造成一定影响。

静力性抗阻训练联合体外冲击波治疗神经根型颈椎病的疗效观察

目的探讨静力性抗阻训练联合体外冲击波(extracorporeal shock wave,ESW)治疗神经根型颈椎病(cervical spondylotic radiculopathy,CSR)的临床疗效。方法使用随机数表法将2021年6月~2022年12月在本院就诊的96例CSR患者分为对照组(n=48)和观察组(n=48)。对照组接受ESW治疗,观察组在ESW治疗基础上接受静力性抗阻训练,两组治疗周期均为20 d。比较两组治疗前后疼痛程度、颈椎活动度和颈椎功能。结果与治疗前相比,两组治疗后VAS评分和NDI评分均下降(P<0.05),而颈椎前屈、后伸活动度和CASCS评分均上升(P<0.05);观察组治疗后VAS评分和NDI评分均低于对照组(P<0.05),而颈椎前屈、后伸活动度和CASCS评分均高于对照组(P<0.05)。结论静力性抗阻训练联合ESW治疗可有效缓解CSR患者疼痛,且能有效提高患者颈椎活动度和颈椎功能。

早期颈部静力性抗阻运动对改善颈椎融合术后轴性症状的效果分析

目的:分析早期颈部静力性抗阻运动对改善颈椎融合术后轴性症状的效果。方法:依据纳入和排除标准自2020年7月至2022年2月在麻城市人民医院行颈椎融合术的颈椎病患者中筛选出124例进行研究,平均分入对照组和观察组。对照组术后给予常规康复训练,观察组术后给予早期颈部静力性抗阻运动。对比两组的颈部软组织张力位移值、颈部活动度、轴性症状严重程度及日常生活活动能力。结果:术后7 d、术后30 d及术后2个月,观察组的颈部软组织张力位移值均大于对照组,差异有统计学意义(P<0.05)。术后2个月,观察组颈部前屈、后伸、左侧屈、右侧屈的活动度均大于对照组,差异有统计学意义(P<0.05)。术后7 d、术后30 d及术后2个月,观察组的轴性症状评分均高于对照组,差异有统计学意义(P<0.05)。术后7 d、术后30 d及术后2个月,观察组的Barthel指数评分均高于对照组,差异有统计学意义(P<0.05)。结论:早期颈部静力性抗阻运动在改善颈椎融合术后轴性症状方面疗效确切,能增加颈部软组织张力和颈椎活动度,提高患者的日常生活活动能力。

不同胁迫条件对食品源MRSA菌株生长、毒力和抗性基因表达的影响

模拟是研究食品加工过程中亚致死条件对耐甲氧西林金黄色葡萄球菌(MRSA)的影响。选取携带不同背景基因的2株猪肉源MRSA菌株(MRSA6和MRSA18),对其进行常用消毒剂、低温、酸碱及渗透压环境胁迫处理,探究处理前、后菌株生长及毒力和抗性基因表达的变化情况。结果表明,消毒剂新洁尔灭胁迫后菌株携带的毒力及抗性基因表达增加,过氧乙酸对菌株不同抗性基因表达的影响存在差异,而对毒力基因表达有抑制作用,次氯酸钠对菌株携带抗性和毒力基因表达有不同程度的抑制作用;低温、高渗及碱胁迫均抑制菌株相关基因表达;酸胁迫处理除对MRSA 6的mecA表达起到明显促进作用外,对其它抗性基因均呈抑制作用。过氧乙酸对菌株的最小抑菌浓度(MIC)为0.03%,次氯酸钠对菌株的MIC为0.17%,新洁尔灭对菌株的MIC为0.0005%,均低于消毒剂推荐使用浓度。低温胁迫对菌株生长无明显影响,55℃胁迫对菌株生长有较好抑制作用,60℃高温可达到较好杀灭效果。菌株表现出对高渗环境的耐受性,在体积分数35%的氯化钠作用下菌株生长受到抑制。低酸环境(pH 2)对菌株生长有较好抑制效果,碱性环境对菌株生长未有明显影响。通过探究不同胁迫条件对MRSA菌株生长及携带毒力和抗性基因表达的影响,发现食品加工中有些亚致死环境条件会使菌株的毒力和抗性表达增加。本研究结果为食品加工过程中抑菌方法的选择及可能对菌株生长及毒力和抗性的影响提供参考。

等长抗阻力性肌力训练治疗颈椎病的临床观测

对94例颈椎病患者分为对照组和康复组,分别采用常规牵引、推拿治疗与外加等长抗阻力性肌力训练治疗,随访半年,康复组总有效率为96.23%(51/53),高于对照组(82.92%,34/41),半年复发率明显低于对照组。

等长抗阻力性肌力训练防治颈型颈椎病的临床研究

目的：探讨等长抗阻力性肌力训练防治颈型颈椎病的作用；方法：将92例患者随机分为对照组及康复组各46例，对照组应用常规推拿，康复组加用等长抗阻力性肌力训练；结果：康复组不仅痊愈率和总有效率都高于对照组（P〈0．05）而且总治疗次数、半年复发率及一年复发率都明显低于对照组（P〈0．05）；结论：等长抗阻力性肌力训练不仅对治疗而且对预防颈型颈椎病都有明显的效果，值得进一步临床研究并广泛推广。

深层搅拌桩支护结构的受力性状分析

利用弹性抗力法对自力式深层搅拌桩支护结构的内力及变形进行了分析。

Mechanical Properties and Thermal Shock Resistance of SrAl_(2)Si_(2)O_(8) Reinforced BN Ceramic Composites

Hexagonal boron nitride(h-BN)ceramics have become exceptional materials for heat-resistant components in hypersonic vehicles,owing to their superior thermal stability and excellent dielectric properties.However,their densification during sintering still poses challenges for researchers,and their mechanical properties are rather unsatisfactory.In this study,SrAl_(2)Si_(2)O_(8)(SAS),with low melting point and high strength,was introduced into the h-BN ceramics to facilitate the sintering and reinforce the strength and toughness.Then,BN-SAS ceramic composites were fabricated via hot press sintering using h-BN,SrCO_(3),Al_(2)O_(3),and SiO_(2) as raw materials,and effects of sintering pressure on their microstructure,mechanical property,and thermal property were investigated.The thermal shock resistance of BN-SAS ceramic composites was evaluated.Results show that phases of as-preparedBN-SAS ceramic composites are h-BN and h-SrAl_(2)Si_(2)O_(8).With the increase of sintering pressure,the composites’densities increase,and the mechanical properties shew a rising trend followed by a slight decline.At a sintering pressure of 20 MPa,their bending strength and fracture toughness are(138±4)MPa and(1.84±0.05)MPa·m^(1/2),respectively.Composites sintered at 10 MPa exhibit a low coefficient of thermal expansion,with an average of 2.96×10^(-6) K^(-1) in the temperature range from 200 to 1200℃.The BN-SAS ceramic composites prepared at 20 MPa display higher thermal conductivity from 12.42 to 28.42 W·m^(-1)·K^(-1) within the temperature range from room temperature to 1000℃.Notably,BN-SAS composites exhibit remarkable thermal shock resistance,with residual bending strength peaking and subsequently declining sharply under a thermal shock temperature difference ranging from 600 to 1400℃.The maximum residual bending strength is recorded at a temperature difference of 800℃,with a residual strength retention rate of 101%.As the thermal shock temperature difference increase,the degree of oxidation on the ceramic surface and cracks due to thermal stress are also increased gradually.

Evolution of mechanical properties,localized corrosion resistance and microstructure of a high purity Al-Zn-Mg-Cu alloy during non-isothermal aging

The evolution of mechanical properties,localized corrosion resistance of a high purity Al-Zn-Mg-Cu alloy during non-isothermal aging(NIA)was investigated by hardness test,electrical conductivity test,tensile test,intergranular corrosion test,exfoliation corrosion test,slow strain rate tensile test and electrochemical test,and the mechanism has been discussed based on microstructure examination by optical microscopy,electron back scattered diffraction,scanning electron microscopy and scanning transmission electron microscopy.The NIA treatment includes a heating stage from 40℃to 180℃with a rate of 20℃/h and a cooling stage from 180℃to 40℃with a rate of 10℃/h.The results show that the hardness and strength increase rapidly during the heating stage of NIA since the increasing temperature favors the nucleation and the growth of strengthening precipitates and promotes the transformation of Guinier-Preston(GPI)zones toη'phase.During the cooling stage,the sizes ofη'phase increase with a little change in the number density,leading to a further slight increase of the hardness and strength.As NIA proceeds,the corroded morphology in the alloy changes from a layering feature to a wavy feature,the maximum corrosion depth decreases,and the reason has been analyzed based on the microstructural and microchemical feature of precipitates at grain boundaries and subgrain boundaries.

论防空地下室结构设计的“八性”

文章对防空地下室结构设计中的特点做了系统总结,概括为延性、塑性、波"动"性、动静荷载等效性、抗力相协调性、防护密闭性、平战兼顾性、经济合理性等八个特性。对广大工程人员学习和理解人防结构设计有指导价值。

牛奶作为一种新型运动饮料的应用前景

近年来,牛奶逐渐走入我国人民日常生活,同时作为一种新型的运动饮料,尤其是在力量训练和耐力训练恢复中的的作用日益引起人们的兴趣。现有的一些研究表明,牛奶可以作为有效的抗力性运动后饮料,促进机体蛋白质代谢发生有益的快速改变。饮用牛奶可以迅速提高骨骼肌蛋白质合成,改善骨骼肌蛋白质平衡。另外,运动后摄入牛奶与较长时期的抗力训练(至少12周)相结合可导致骨骼肌及瘦体重的更加显著性增长。

Effects of Sunflower Artificial Aging on Seed Vigor and Physiological Characteristics

[Objective]The aim was to study the effects of sunflower artificial aging on seed vigor and physiological characteristics.[Method] The varieties of seed germination capacity,vigor of germination,germination index,vigor index,peroxidase（POD） activity,superoxide dismutase（SOD） activity and malondialdehyde（MDA） content for four sunflower germplasms such as＇SunM20＇,＇Deep Purple Minle＇,＇Da San Kui Hua 4＇and＇Ji Kui 24＇were studied under high temperature and high humidity conditions（100% RH,45 ℃） for different days（0 d,2 d,4 d,6 d,8 d,10 d）.[Result]The result showed that the germination capacity,vigor of germination,germination index,vigor index,POD activity,SOD activity declined gradually with the increase of seed aging days,whereas MDA content enhanced by degrees;The diggerences of resistance to artifical aging existed among the four accessions,＇SunM20＇was the most resistant one,and exhibited the strongest seed vigor,highest activities of two protective enzyme（POD,SOD） and lowest content of MDA at the uniform condition,moreover,the seed vigor and protective enzyme activities of＇SunM20＇changed slowest among the four materials during the aging process.[Conclusion]The distinct reduction of POD,SOD activities maybe the main reasons for the decrease of sunflower seed vigor at the artificial aging,and the gradual accumulation of a few MDA accelerated seeds aging.

Shear resistance performance of steel-concrete-steel composite shear wall

For a deeper understanding of the shear resistance performance of the steel-concrete-steel composite shear wall, the main influence factors such as the thicknesses of the steel plates and the concrete, the strength grades of the concrete and the span-depth ratios of the composite wall, which have impacts on the shear resistance performance of the composite shear wail, are analyzed by the numerical simulation method. Meanwhile, the simplified calculation formulae of the initial elastic lateral-resisting stiffness and the shear bearing capacity of the composite shear wall are also proposed. The research shows that with the increase in the thicknesses of the steel plates and the concrete and the increase in the strength grades of the concrete, the shear performance of the shear wall improves obviously; the span-depth ratios of the composite wall have a significant effect on the initial elastic lateral- resisting stiffness, but a small effect on the shear bearing capacity. Comparing the results of the simplified calculation formulae with those of the nonlinear finite element method, it is obvious that the presented formulae are reasonable and meet the real force state of the structure. These conclusions can serve as a preliminary design reference for the steel-concrete- steel composite shear wall.

Experimental validation of horizontal joints in an innovative totally precast shear wall system

To investigate the feasibility and seismic performance of the horizontal joints in an innovative precast shear wall system, two test walls were fabricated, and the monotonic and cyclic loading tests were performed on the two test walls, respectively. Then, the lateral load-top displacement curves, load beating capacity, ductility, lateral stiffness, strains of steel bars, strain distribution on the connecting steel frame （CSF）, and relative slippages between the CSF and embedded limbic steel frame （ELSF） were discussed in detail. The test results show that the load bearing capacity and ductility of the test wall are both favorable with a displacement ductility factor of more than 3.7. The normal and shear stresses in the CSF except for the compression end are far smaller than the yield stresses throughout the test procedure. Certain slippages of about 1.13 mm occurs between the CSF and ELSF on the compression side of the test wall, while almost no slippages occurs on the tension side. The seismic performance of the test wall is favorable and the new-type scheme of the horizontal joints is both feasible and reliable.

Microstructure, mechanical and oxidation characteristics of detonation gun and HVOF sprayed MCrAlYX coatings

Microstructure, mechanical property and oxidation resistance of MCrAlYX coatings prepared by detonation gun (D-gun) and HVOF spraying were investigated. Lamellar microstructure and uniform microstructure formed in D-gun sprayed MCrAlYX coating and HVOF sprayed coating, respectively. Element redistribution and formation of new phase took place during the detonation process. Besides, the porosity of D-gun sprayed coating was much lower than that of HVOF sprayed coating. On the mechanical property, the micro-hardnesses of the two coatings were in the same level (~HV 910). However, D-gun sprayed MCrAlYX coating exhibited larger standard deviation of microhardness due to its lamellar microstructure, and exhibited better bend bonding strength owing to the existence of residual compressive stress between the layers and particles. Meanwhile, due to the much more compact microstructure, D-gun sprayed MCrAlYX coating showed superior oxidation resistance to the HVOF sprayed coating. The continuous dense protective layer can form earlier in D-gun sprayed coating and thus suppress further oxidation and control the oxide thickness at a relatively low level.

Study on Application of Microbial Ecological Agents, Replacements for Antibiotics, in Weaned Piglet Production

In order to investigate the appIication effects of microbial ecoIogical agents as repIacements for antibiotics in weaned pigIets, a total of 120 28 d oId healthy Duroc ＆#215;Landrace ＆#215;Large White weaned pigIets with simiIar bogy weights and body fats and cIose birth dates were seIected. They were randomIy divided into three groups, incIuding controI group （CK）, antibiotic group （A） and microbial ecoIogical agent group （MEA）. The growth performance, health status and economic benefits of the weaned pigIets were measured. The resuIts showed that the A and MEA groups couId better enhance the immunity of weaned pigIets and improve the economic benefits in the whoIe experimental period compared to the CK group （P〈0.01）. How-ever, there were no significant differences in pigIet immunity and economic benefits between the A and MEA groups （P〉0.05）. It is indicated that the Rujunbao, a mi-crobial ecoIogical agent, can be promoted in weaned pigIet production as a repIace-ment for antibiotic.

Tensile and wear properties of TiC reinforced 420 stainless steel fabricated by in situ synthesis

TiC particle reinforced 420 stainless steel matrix composites were fabricated, and the microstructure, tensile properties and wear resistance of the composites were studied. The experimental results indicate that the distribution of TiC particles with size of 5 to 10 μm in diameter is uniform if the volume fraction of TiC is lower than 6%. However, slight agglomeration can be observed when the TiC content exceeds 6%. With the increase of TiC content the tensile and yield strength of the composites prepared increases and reaches the maximum when the volume fraction of TiC increases to 5%. Further increase of TiC content causes reductions of yield and tensile strength. The ductility of the composites shows a monotone decrease with the increase of TiC addition. The introduction of TiC into 420 stainless steel results in significant improvement on wear resistance, which reaches a steady level when the volume fraction of TiC increases to 11% and does not show obvious variation if the TiC content is further increased.

Effect of LaCl_3 on Resistance and Absorptive Capacity to Formaldehyde of Indoor Ornamental Plants under Formaldehyde Stress

[Objective] This study aimed to determine the effect of rare earth biological regulator LaCl3 on the absorptive capacity to formaldehyde of four indoor ornamental plants, and to screen out the plant whose absorptive capacity to formaldehyde can be increased most greatly by LaCl3. [Method] Effect of LaCl3 on absorptive capacity to formaldehyde of four indoor ornamental plants was studied through fumigating in laboratory. Simultaneously, the indoor ornamental plant, which could significantly en- hance the degradation capacity of formaldehyde, was screened out to study the physiological and biochemical mechanisms of formaldehyde resistance. [Result] The ability to absorb formaldehyde of four indoor ornamental plants was enhanced by dif- ferent ranges after spraying with LaCl3 at suitable concentrations. The ability to ab- sorb formaldehyde of Hedera nepalensis var. sinensis, Chlorophytum comosum, Scindapsus aureun and Sansevieria trifasciata increased by 15.16%, 4.72%, 19.75% and 7.68%, respectively. In the four indoor ornamental plants, the capacity of S. au- reun to absorb formaldehyde was greatly improved by spraying LaCl3. When S. au- reun was stressed by formaldehyde, its chlorophyll content decreased by 39.87%, membrane permeability, MDA accumulation and POD activity increased by 8.17%, 56.92%, and 11.32%, respectively. However, compared the pre-spraying group with the no-spraying group under formaldehyde stress, chlorophyll content of S. aureun reduced less, membrane permeability and MDA cumulative both increased less, but POD activity increased more. [Conclusion] The formaldehyde absorption capacity of S. aureun was mostly improved after LaCl3 was sprayed.