固定矫治联合微种植体支抗在青少年安氏Ⅱ类错(牙合)畸形治疗中的应用

目的:探讨固定矫治联合微种植体支抗治疗青少年安氏Ⅱ类错(牙合)畸形患者的疗效。方法:将2019年1月-2021年12月笔者医院收治的85例安氏Ⅱ类错(牙合)畸形患者纳入研究。根据是否配合使用微种植体支抗分为对照组(n=42)和观察组(n=43)。对照组患者采用固定矫治器治疗,观察组患者采用固定矫治联合微种植体支抗治疗。随访1年,比较两组SNA角、SNB角、GO-GN-SN角、OP-SN角等颌面部指标,比较两组前牙覆(牙合)覆盖、磨牙咬合关系、中线关系等错(牙合)畸形指标。治疗后,两组生活质量采用SF-36生活质量量表评估比较,采用医院自制外观功能满意度对两组矫治满意度进行评估比较。结果:治疗后,两组SNA值略有下降,SNB值、GO-GN-SN值、OP-SN值略有增加,且观察组SNA值低于对照组,SNB值、GO-GN-SN值、OP-SN值均高于对照组(P<0.05);治疗后,两组前牙覆盖、前牙覆(牙合)、磨牙咬合关系、中线关系评分均低于治疗前,且观察组低于对照组(P<0.05);治疗后,观察组心理功能、运动功能、饮食功能及生理功能等生活质量评分均高于对照组(P<0.05);治疗后,观察组外形、舒适度、咬合功能和便捷性等满意度评分均高于对照组(P<0.05)。结论:青少年安氏Ⅱ类错(牙合)畸形患者应用固定矫治器联合微种植体支抗治疗效果显著,可有效改善患者颌面部组织形态,降低错(牙合)畸形严重程度,提高患者生活质量,患者满意度更高。

水泥-沥青-环氧树脂复合胶结道路快速修补材料研究

我国公路交通总里程已达446.4万km,位居世界第一,其中服役寿命超过10年的沥青路面达到150.5万km,按我国规范要求的设计使用寿命为15年计算,未来几年我国将处于道路维修与养护的高峰期,亟需性能优异的路面维修养护材料。针对普通沥青路面修补材料温度敏感性大、与维修路面黏结强度低、耐久性差等问题,采用硫铝酸盐水泥、乳化沥青、水性环氧和外加剂等进行复合,开发高强、高黏结强度、低模量的新型的道路快速修补材料,该材料具有优良的路用性能和耐久性能,可用于各等级沥青路面和混凝土路面维修养护工程,提高路面的服役寿命,具有推广应用前景。

水泥工业在国家“双碳”战略中大有作为

建材行业是国民经济和社会发展的重要基础产业,我国正处于经济社会高质量发展的关键时期,重大基础设施和大规模城镇化建设对建筑材料需求量巨大,如此带来建筑材料生产原料资源消耗和CO_(2)排放量也非常巨大。与此同时,全球因温室气体增加气候变暖和生态环境劣化对我们人类传统的生产生活方式提出了严峻挑战。

Al_(2)O_(3)掺杂对γ-C_(2)S碳化性能的影响

本文研究了Al_(2)O_(3)掺杂对γ-C_(2)S熟料粒径、微观结构和力学性能的影响。试验结果表明:Al_(2)O_(3)掺杂不会改变γ-C_(2)S的晶型,但显著改变了其形貌;纯相γ-C_(2)S颗粒表面褶皱较多,颗粒尺寸较大,掺杂Al_(2)O_(3)后γ-C_(2)S颗粒表面褶皱消失而变得光滑;γ-C_(2)S碳化体的抗压强度与碳化程度随着Al_(2)O_(3)掺量的提高逐渐增加。通过碳化反应温升并结合碳酸钙衍射峰的半峰宽和X射线衍射仪(XRD)定量分析表明,Al_(2)O_(3)掺杂延缓了碳化放热,有利于碳化反应的持久进行,同时促进了碳酸钙晶粒的生长和数量的增加,从而使碳化程度更高,基体结构更加密实,因而抗压强度更高。

化学驱动与热力学驱动下复合胶凝体系的水化特性研究

为了解复合胶凝材料体系水化放热特性,以及化学驱动与热力学驱动对复合胶凝材料体系的水化放热影响,研究了不同掺量的粉煤灰/矿粉-水泥二元复合胶凝体系的水化热发展,同时探究了不同早强剂掺量以及不同温度对粉煤灰-水泥二元复合胶凝体系水化放热的影响。结果表明:粉煤灰、矿粉均会降低二元复合胶凝体系水化放热速率,但矿粉活性比粉煤灰高,对水化放热速率以及最终累计放热量影响较小;化学驱动可以显著提高体系水化放热速率,促进早期水化发展,但不改变最终累计放热量;热力学驱动作用效果更显著,可以大幅提高体系放热曲率以及累计放热量。以化学反应速率为判据构建两种驱动的联系能有效地设计混合驱动模式。

区域经济韧性:支持产业结构多样性的新思想

产业结构的多样性与专业化之争是经济学中一个长期热门的话题。对外部性的不同理解导致产业结构的多样性与专业化之争,基于演化思想的相关多样性概念的提出,让两者从争论走向融合。自2007年Martin提出区域经济韧性以来,众多学者基于区域经济韧性的考虑,倾向于支持产业多样性。未来产业结构多样性与专业化的选择需要考虑时间、行业、区域等因素,更多地关注产业之间的联系和区域尺度的转变,从而更清晰地界定产业结构对区域经济增长的影响。

Effect of Calcium Silicate Hydrate Seeds on Hydration and Mechanical Properties of Cement

C-S-H series are synthesized at different temperatures and ages by pozzolanic reaction.The change of particle size distribution,phase composition,morphology and nanostructure of C-S-H with temperatures and ages,and the effects of C-S-H seeds and seeds parameters on the hydration behavior and mechanical properties development of cement were investigated by DLS,XRD,SEM,^(29)Si NMR,TAM-air isothermal calorimeter and mechanical properties test.The results show that the particle size,crystallinity,basal spacing and Q^(2)/Q^(1) ratio of C-S-H increases with the increase of synthesis temperature and age.The addition of synthesized C-S-H seeds to cement pastes results in the strong acceleration effect on cement hydration and significant improvement of the early strength of cement paste and mortar.The 1 day-C-S-H seeds synthesized at room temperature can increase the strength of cement paste by about 30 MPa at 12 h.The effect does not show a very regular change with the increase of the temperature and age of seeds synthesis.Considering the effect of C-S-H seeds on the hydration and mechanical properties of cement,and economy and short cycle of seeds synthesis,the C-S-H seeds synthesized at room temperature for 1 day or 55 ℃ water bath for 12 hours is recommended..

Effect of Polymer on Morphology and Structure of Calcium Silicate Hydrate Prepared via Precipitation Method

The effects of polyaerylamide （PAM） and polyvinyl alcohol （PVA） on morphology and structure of calcium silica~ hydrate with C/S 1.0-1.7 prepared via precipitation in solution were investigated by XRD, FT-IR and TEM techniques. The results show that incorporation of the polymers decreased the order degree, increased the interlayer spacing and disturbed the layered stacking of C-S-H. Interlayer spacing expansion depended on C/S ratios and type of polymer. Interlayer spacing expansion had a minimum at C/S 1.0 and a maximum at C/S 1.3 and 1.5. Interlayer spacing expansion of PAM was bigger than that of PVA with the same C/S. C-S-H added with PVA mainly exhibited foil-like and fibrillar morphology. The fibrils were of variable length from a few tens of nanometers to a few hundreds of nanometers. Fibrils or foils seemed to be longer in the presence of PVA.

Improvement of the FRP Sheet Bonded to Concrete Substrate by Silane Coupling Agent

We experimentally studied the fine lightweight aggregate with the particle size range of 3.15-4.75 mm used as functional bridge between FRP sheet and concrete substrate. However, problems would appear and how to deal with the interfacial transition zone（ITZ） and make it stronger is the key point for this concept. Considering that silane coupling agent（SCA） can provide a better bond on a silicon-containing material surface, it was introduced as a modifying material to further improve the bond quality of the ITZ between lightweight aggregate and cement paste. Results indicated that the water absorptivity of lightweight aggregate can be controlled by SCA solutions, and the pull-off bond strength, mechanical strength, and microhardness were increased, which was attributed to the optimized microstructure under the condition of an appropriate concentration of SCA.

Hydration Products of Cement-silica Fume-quartz Powder Mixture under Different Curing Regimes

Composition, morphology, and structure of hydration products in hardened pastes of three kinds of blended cement（cement-silica fume, cement-quartz powder and cement-silica fume-quartz powder） hydrated under different curing regimes（standard curing, 90 ℃ steam curing, 200 ℃ and 250 ℃ autoclave curing） were investigated by X-ray diffraction and field emission scanning electron microscope equipped with EDAX system. Results showed that the main hydration products in three kinds of hardened pastes under standard curing condition are all C-S-H gels, CH, and AFt. Under 90 ℃ steam curing condition, the main hydration products of cement-silica fume and cement-silica fume-quartz powder are C-S-H gels, whereas those of cement-quartz powder are C-S-H and CH. Under 200 or 250 ℃ autoclave curing condition, no obvious crystallized CH phase is found in hardened pastes of three kinds of blended cement, and C-S-H gels are transformed into one or more crystalline phases such as tobermorite, jennite, and xonotlite. The chemical composition and morphology of these crystalline phases depend on the composition of mixture and autoclave temperature.

Microstructure and Properties of Cement Foams Prepared by Magnesium Oxychloride Cement

Microstructural features including pore size distribution, cell walls and phase compositions of magnesium oxychloride cement foams（MOCF） with various MgO powders and water mixture ratios were studied. Their infl uences on compressive strength, water absorption and resistance of MOCF were also discussed in detail. The experimental results indicated that moderate and slight excess MgO powders（MgO/MgCl2 molar ratios from 5.1 to 7） were beneficial to the formation of excellent microstructure of MOCF, but increasing water contents（H2O/MgO mass ratios from 0.9 to 1.29） might result in opposite conclusions. The microstructure of MOCF produced with moderate and slight excess MgO powders could enhance the compressive strength, while serious excess MgO powders addition（MgO/MgCl2 molar ratios = 9） would destroy the cell wall structures, and therefore decrease the strength of the system. Although MOCF produced with excess MgO powders could decrease the water absorption, its softening coefficient was lower than that of the material produced with moderate MgO powders. This might be due to the instability of phase 5, the volume expansion and cracking of cell walls as immersed the sample into water.

Versatile Surface Modification of Ceramsite Via Honeycomb Calcium-aluminum-silicate-hydrate and Its Functionalization by 3-thiocyanatopropyltriethoxysilane for Enhanced Cadmium(Ⅱ) Removal

A low-cost and efficient filter medium for Cd(Ⅱ) removal was prepared by anchoring-SCN functional groups(by 3-thiocyanatopropyltriethoxysilane, TCPS) on ceramsite via the approach of synthesizing a honeycomb calciumaluminum-silicate-hydrate(C-A-S-H) layer as intermediate. The specific surface area of ceramsite was increased enormously by more than 50 times because of the modification of honeycomb layer. Moreover, the abundant Si-OH bonds existing in the structure of CAS-H can serve as active sites for TCPS. The combined effects ensure that the hybrid filter medium(named ceramsite/C-A-S-H/TCPS) demonstrated a high Cd(Ⅱ) adsorption capacity of 18.27 mg·g^-1 for particle size of 0.1-0.6 mm, 12.63 mg·g^-1 for 0.6-1.25 mm and 8.64 mg·g^-1 for 1.25-2.35 mm. The Cd(Ⅱ) adsorption capacity per unit area of ceramsite/C-A-S-H/TCPS(0.1-0.6 mm) is up to 4.07 mg·m^-2, which is much higher than that of many nano-adsorbents. In addition, ceramsite/C-AS-H/TCPS could maintain a high removal efficiency(> 85%) in a wide range of p H 3-11 and showed excellent selectivity in the presence of competing ions. Furthermore, Cd(Ⅱ) could be desorbed from ceramsite/C-A-S-H/TCPS composites with nearly 100%, suggesting the potential application in recycling of heavy metal ions.

Mechanical Performance and Micro-structure of Pore Steel Slag Block Prepared by Accelerated Carbonation

Steel slag contains a large amount of calcium silicate,which can react with CO_(2)to generate CaCO_(3)and SiO_(2)colloid,thus steel slag may become a cementitious material with a certain strength.High strength porous steel slag carbonated brick was prepared by adding easily decomposed bicarbonate solid into steel slag as pore-forming agent and then accelerating carbonation.A variety of characterization methods were used to characterize the composition and micro-structure of the samples.The effects of different pore-forming agent dosage and carbonation time on the properties of pore steel slag blocks were discussed.The results show that the addition of ammonia bicarbonate promotes the nucleation and growth of columnar calcite.The strength of steel slag block mixed with 30%pore forming agent can reach 24.8 MPa after 1 day of carbonation,and then the strength development tends to slow down.

Effect of Calcium Carbonate Whisker on Impact Toughness of Precast Concrete

The impact toughness and compressive strength of concrete added with calcium carbonate whisker are studied.It is found that calcium carbonate whisker can significantly improve the impact energy consumption at failure of 55℃steam cured concrete,but has limited impact on 90℃steam cured concrete.At the same time,SEM,XRD and LF-NMR were used to study the micro morphology,hydration product components and pore structure of the concrete,and the mechanism of the influence of calcium carbonate whisker on the impact toughness and compressive strength of concrete was analyzed.

新时代博物馆文物保护工作提升策略研究——以河南博物院为例

随着时代的发展,博物馆的文物保护工作对于传承、研究和利用中华优秀传统文化的作用日益凸显。但是,在相关工作开展过程中,博物馆普遍存在文物保护工作创新能力不强和文物修复技术水平不高等问题。文章阐述了新时代博物馆开展文物保护工作的意义,结合河南博物院的文物保护工作实际,分析了博物馆在文物保护工作过程中存在的问题,提出了博物馆文物保护工作提升策略,以期推动文博事业的发展。

Dehydration Characteristics of C-S-H with Ca/Si Ratio 1.0 Prepared Via Precipitation

Calcium silicate hydrate（C-S-H） with Ca/Si ratio 1.0 was prepared via precipitation in solution and heated at various temperatures to investigate its dehydration behavior. The dehydration, structural collapse and recrystallization characteristics of C-S-H and its microstructural change during heating process were investigated by XRD, SEM, Raman and TG-DSC techniques. C-S-H gradually lost non-evaporable water upon heating, about 50% and 80% non-evaporable water was removed below 200 and 400 ℃, respectively, and the rest was removed up to about 1 000 ℃. At 400 ℃, dehydrated C-S-H exhibited the increasing disordering of calcium/silicon environment and the decreasing symmetrical bending vibration of Si-O-Si of Q^2 silicate chains. At 650 ℃ non-bridging oxygen atoms（O（non）） attached to silicon were almost removed, and significant structural change occurred, and at 815 ℃ C-S-H dehydrated to wollastonite.

Hydration Mechanism of Silica Fume- sulphoaluminate Cement

Setting time and strength of sulphoaluminate rapid hardening cement （SAC） incorporated in the presence and absence of silica fume （SF） were determined. Combined with the techniques of＂ isothermal calorimeter, XRD and FSEM, the hydration kinetics of the two systems and the effect mechanism of SF on SAC were investigated. The experimental results showed that SF was proved to be beneficial for SAC system, in terms of setting time and late strength gain. Evidence of accelerator effect of silica fume was found during the first 8 hours of hydration. The formation of AFt was accelerated and the microstructure of the hydration products grew denser with incorporation of SF. SF was proved to play the role of dispersion and setting control at early age and had a greater contribution to later strength due to the increment of crystal nucleation point and the pozzolanic activity. Therefore, SF can be used to not only control the hydration kinetics of SAC, but also develop the late strength and improve the microstructure.

Effects of Steam Curing on the Resistance of Cementitious Materials to Chloride Penetration

The resistance to chloride penetration of cement-based material with different curing regimes was investigated by solution titration,XRD,LF-NMR and rapid chloride migration test.The results show that the curing regime has influences on the types and structure of the hydration products,which in turn affects their ability to bind chloride ions.The binding capacity of cementitious materials to chloride ions,porosity and chloride ion migration coefficient increased with the increase of water-cement ratio,while steam curing increased the porosity and chloride ion migration coefficient at the same time as it increased the chloride ion binding capacity of the materials.At lower water-cement ratios,the effect of steam curing on the resistance of cementitious materials to chloride ingress is negligible.

Porous Haydite Used as Waste Water Filter Medium for Lake Sludge

Porous haydite used as waste filter medium was prepared by dreging lake sludge to help solve the treatment problem of sludge and realize its reclamation. Several calcination regimes were considered and their effects on the pore structure and the properties such as the strength, the density, the filtering ability and the phosphate absorption ability of the haydite were investigated, For the mixture of 60% lake sludge and 40% fly ash in this experiment, the calcination regime with a pre-caleination period at about 600℃, a temperature keeping period at 1 200 ℃ and a moderate cooling rate are recommended to prepare haydite with reasonable pore structure and good performances for its usage as the waste water filter media.

Mechanism of Suppressing ASR Using Ground Reactive Sandstone Powders instead of Cement

In order to understand the effect of powders ground from reactive sandstone replacing cement on reducing or suppressing alkali-silica reaction（ASR）, and to identify the mechanism of suppressing ASR by this powders, mortar and paste containing reactive sandstone powders of four replacement levels ranging from 10wt% to 40wt% and four specific surfaces areas ranging from 210 m^2/kg to 860 m^2/kg were studied. The experimental results showed that incorporation of 40wt% reactive sandstone powders could suppress ASR effectively except for mortar containing reactive sandstone powders with specific surface area of 610 m^2/kg, which disagreed with the most results reported that the higher reactive powder specific surface area, the smaller ASR expansion. By means of fl ame photometry, Fourier transform infrared spectroscopy（FT-IR） and thermo gravimetric analysis（TG）, the mechanism of reactive sandstone powders on reducing or suppressing ASR was soluble alkalis type of reactive sandstone powders and the competition of liberating and bonding alkali of cement paste containing reactive sandstone powders,when the ability of alkali bonding was greater than the ability of alkali liberation, ASR caused by reactive sandstone was supressed effectively.