La-doped Pt/TiO_2 as an efficient catalyst for room temperature oxidation of low concentration HCHO

Catalytic oxidation of formaldehyde (HCHO) is the most efficient way to purify indoor air of HCHO pollutant. This work investigated rare earth La‐doped Pt/TiO2 for low concentration HCHO oxidation at room temperature. La‐doped Pt/TiO2 had a dramatically promoted catalytic performance for HCHO oxidation. The reasons for the La promotion effect were investigated by N2 adsorption, X‐raydiffraction, CO chemisorption, X‐ray photoelectron spectroscopy, transmission electron microscopy(TEM) and high‐angle annular dark field scanning TEM. The Pt nanoparticle size was reduced to 1.7nm from 2.2 nm after modification by La, which led to higher Pt dispersion, more exposed activesites and enhanced metal‐support interaction. Thus a superior activity for indoor low concentrationHCHO oxidation was obtained. Moreover, the La‐doped TiO2 can be wash‐coated on a cordieritemonolith so that very low amounts of Pt (0.01 wt%) can be used. The catalyst was evaluated in asimulated indoor HCHO elimination environment and displayed high purifying efficiency and stability.It can be potentially used as a commercial catalyst for indoor HCHO elimination.

Optimum Calcination Condition of Waste Stabilized Adobe for Alkali Activated High Volume Adobe-Slag Binder Cured at Room Temperature

This study aims to determine the most convenient calcination temperature and calcination duration of wastestabilized Adobe(AB)to produce a new alkali-activated binder.Waste-stabilized Adobe mainly consists of soil,CaCO3 as a stabilizer,and straw(for strengthening).The availability of raw materials for making Adobe presents the waste-stabilized Adobe as a potential product for a new alkali-activated binder.Waste-stabilized Adobe collected from an abandoned damaged building in the village of Inonu in Northern Cyprus,ground and calcined at the following temperatures:450,550,650,750,850,and 950℃.The calcination at each temperature was held for different durations 1,3,5,and 7 h.Raw and calcined waste stabilized Adobe structures were investigated using XRF,TGA-DTA,XRD,FTIR,and SEM.Considering technical and environmental views related to energy consumption,waste stabilized Adobe calcined at 750℃ for 1 h presented the most promising results regarding the production of a new precursor for alkali-activated binder.This study also presents the effect of ground granulated blast furnace slag(GGBFS)usage on the fresh and hardened properties of optimum calcined AB-based alkali-activated pastes cured at room temperature.GGBFS was used to partially replace AB to form a binary composite raw material system and seven experimental groups were designed according to replacement levels of 0%,5%,10%,15%,20%,25%and 30%(by mass).Alkali-activated high volume waste-stabilized Adobe-slag pastes prepared using Na2SiO3-to-NaOH ratio of 2 and 12 M concentration of Sodium Hydroxide.The fresh property as flowability and the hardened property as the compressive strength of the alkali-activated pastes with different GGBFS contents were investigated.The results indicated that the incorporation of GGBFS increased the flowability of fresh alkali-activated pastes.A 28-day compressive strength of 43.75 MPa can be obtained by a 30%replacement level of GGBFS.

Hydrophilicity Modification of Addition-cured Room Temperature Vulcanization Silicone Rubber

Allyl terminated polyether was used to improve the hydrophilicity of addition-cured room temperature vulcanization silicone rubber. With the increasing of the polyether, both the hydrophilicity and water absorbed of the vulcanizates were increased. The mechanical properties were also improved by adding the polyether. The result showed that 1.5wt% of the polyether provided the silicone rubber with proper hydrophilicity.

Risk Regionalization of Low-temperature Disasters for Flue-cured Tobacco Planting in Qujing Area Based on GIS

There is a prominent,complex and diverse three-dimensional climate and a variety of meteorological disasters in Qujing area. The risk zoning of low-temperature disasters for flue-cured tobacco planting in Qujing area was studied to provide reference for drawing on advantages and avoiding disadvantages in flue-cured tobacco planting,disaster reduction,and disaster relief services. According to the production practice of fluecured tobacco and local climate analysis,it was determined that flue-cured tobacco in Qujing area was very vulnerable to low temperature during the seedling stage（ from early February to middle April） and in the mature period（ from early July to early September）. Based on the quantitative analysis and evaluation of risk of disaster-causing factors,sensitivity of disaster-breeding environment,vulnerability of carriers,and disaster prevention and reduction capability,a risk assessment model of meteorological disasters was established to precisely evaluate and zone the risk of low-temperature disasters for flue-cured tobacco planting in allusion to the seedling and mature stage in Qujing area by using GIS technology. The risk of lowtemperature disasters for flue-cured tobacco planting during the two periods was divided into four grades,namely low,medium,high and very high risk.

Enhancement of room-temperature magnetoresistance in La_(0.5)Sm_(0.2)Sr_(0.3)MnO_3/(Ag_2O)_(x/2)

La0.5Sm0.2Sr0.3MnO3/（Ag2O）x/2 （x = 0.00, 0.04, 0.08, 0.25, 0.30） samples were prepared by the solid-state reaction method, and their transport behaviors, transport mechanism, and magnetoresistance effect were studied through the measurement and fitting of p-T curves. The results show that the element Ag takes part in reaction when the doping amount is small. Ag is mainly distributed at the grain boundary of the host material and is in metallic state when the doping amount is relatively large; then the system becomes a two-phase composite. A small amount of Ag doping can apparently increase grain-boundary magnetoresistance induced by the spin-dependent scattering. The resistivity of the sample doped with 30 mol% Ag is one order of magnitude smaller than that of low-doped samples, and its magnetoresistance in the magnetic field of 0.5 T and at 300 K is strengthened apparently reaching 9.4%, which is connected not only with the improvement of the grain-boundary structure of the host material but also with the decrease of material resistivity.

Enhancement of room-temperature magnetoresistance in La_(0.6)Dy_(0.1)Sr_(0.3)MnO_3/Ag_x

The samples of La0.6Dy0.1Sr0.3MnO3/（Ag2O）x/2（x = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10, 0.20, 0.25, and 0.30） were prepared by using the solid-state reaction method.Their magnetic property, transport behavior, transport mechanism and magnetoresistance effect were studied through the measurements of magnetization-temperature（M-T） curves, ρ-T curves and the fitting of ρ-T curves.The results indicated that Ag could take part in the reaction when the doping amount is small.However, when the doping amount is comparatively large, Ag as metallic state mainly deposits on the grain boundary of La0.6Dy0.1Sr0.3MnO3, and then the system forms a two-phase composite.When the Ag doping amount is 30% mole ratio, the resistivity of the sample is one order of magnitude smaller than that of low doped samples, and its peak of magnetoresistance at 292 K and in the magnetic field of 0.2 T strengthens apparently and reaches 16.3%, which is over 7 times as large as 2.2% of La0.6Dy0.1Sr0.3MnO3.The two-phase composite system of magnetoresistance based on perovskite manganite consists of two parts：intrinsic magnetoresistance and extrinsic magnetoresistance.However, extrinsic magnetoresistance comes from spin-dependent scattering（SDS） and spin-polarized tunneling（SPT）.Magnetoresistance near TC increases due to the contribution of intrinsic magnetoresistance and extrinsic magnetoresistance formed by SDS, and magnetoresistance at low temperature is extrinsic magnetoresistance formed by SPT.

Influence of Curing Accelerators on the Imidization of Polyamic Acids and Properties of Polyimide Films

In order to lower the imidization temperature of polyamic acids（PAA）, the catalytic activities of the curing agents p-hydroxybenzoic acid（PHA）, quinoline（QL）, benzimidazole（BI）, benzotriazole（BTA）, triethylamine（Et_3N） and 1, 8-diazabicyclo [5.4.0]undec-7-ene（DBU） were investigated in the process of thermal imidization of PAA. In addition, the effect of these various curing agents on the thermal stabilities and mechanical properties of the resultant polyimide（PI） films was determined. Quinoline was found to be an effective curing accelerator in the use of two-step method for synthesizing PI. Due to its moderate base strength, low steric crowding effect and moderate boiling point, quinoline could not only accelerate PAA to achieve imidization completely at 180 ℃, but also maintain the mechanical properties and thermal stability of the ordinary PI film. Any residual quinoline could be removed from PI films by heating at 250 ℃ for 4 h.

Robust Polystyrene/Fluorinated Silica Superhydrophobic Composite Coatings with Rapid Curing at Room Temperature Prepared by One-Step Spraying

Superhydrophobic materials are severely limited in their applications due to their weak mechanical properties and complex preparation process.In this paper,polystyrene/fluorinated silica(PS/SiO_(2))superhydrophobic composite coatings were prepared on the surface of 304 stainless steel using a simple one-step spraying method.The effects of different PS contents on the wettability as well as the wear properties of the samples were investigated.SiO_(2) was encapsulated in polystyrene to form a structure similar to cement encapsulated stones.With the addition of PS,a mound-like structure was formed on the sample surface,and a more optimized micro–nano structure was obtained when the content of PS was 0.6 g.At this time,the sample exhibited excellent wettability with a contact angle of 157.86°and a sliding angle of 0.84°.In addition,the contact angle of 151.09°was achieved after 180 cm of friction under a 100 g load and the composite coating prepared by this method also has excellent chemical stability,water impact resistance,corrosion resistance,and self-cleaning properties.This opens up new possibilities for the development of simple and robust superhydrophobic materials.

Influence of Curing Duration on Thaumasite Formation of Portland-limestone Cement Pastes

Extensive researches have been carried out on the conventional sulfate attack, while it has been found that the thaumasite form of sulfate attack（TSA）, sulfate attack at low temperature, has just been discovered and its mechanism is not well understood so far. In this study, the sulfate attack of cement paste incorporating 30% mass of limestone powder was investigated. After 20 ℃ water cured for 7, 14, and 28 days,respectively, 20 mm cube specimens were exposed in a 5% magnesium sulfate solution at（6 ±1） ℃ for periods up to 240 days. Their appearance change, compressive strength development were examined at different storage time, and selected paste samples were examined by X-ray diffraction（XRD）, Fourier transform infrared spectroscopy（FTIR）, scanning electron microscopy（SEM） and energy dispersive spectroscopy（EDS）. The results indicate that all Portland-limstone cement pastes suffer from appearance deterioration to some extent. The compressive strength of cement paste initially increases and after 120 days decreases with increasing exposed period. In addition, the cement paste with short curing time is more susceptible to sulfate attack, which directly leads to the formation of non-binder thaumasite crystal accompanied by the formation of ettringite, gypsum and brucite, and becomes a white, mushy, and incohesive matrix. Additionally, the extent of sulfate attack is greater and the formation of thaumasite is observed earlier for shorter curing time.

某锂矿低温熟化—水浸提锂和提纯高纯石英新工艺

皖南低品位热液蚀变型锂矿Li_(2)O含量0.21%,属于新类型锂矿资源,主要矿物成分有长石、石英、白云母、绿泥石,锂主要以晶格形式赋存于锂绿泥石中。新工艺采用-1 mm原矿筛分,+0.425 mm粒级进入磨矿,制备-0.425+0.074 mm合格粒级。脱泥后合格粒级产品经磁选得云母精矿,非磁性物浮选得到长石精矿和石英精矿,长石精矿和云母精矿分别进行提锂,石英精矿进行酸处理提纯得高纯石英。将原矿筛出的-0.074 mm细泥、再磨产生的-0.074 mm细泥、合格粒级搅拌擦洗产生的-0.074 mm细泥,合并为总泥进行后续提锂。试验结果表明:总泥、云母、长石分别采用低温熟化—水浸工艺提锂,累计得Li_(2)O浸出率88.78%,酸浸后石英精矿含SiO_(2)99.942%,Fe 4.38 mg/kg,达到高纯石英低端产品要求,提锂后的长石和云母浸渣产率54.48%,可用于建筑材料。浸出前后样品的XRD和SEM分析表明,硫酸低温熟化破坏了锂绿泥石晶格结构,H+代替锂绿泥石中Li+,将锂释放出来。新工艺降低了磨矿成本,锂浸出率高,兼顾云母、石英、长石的回收,减少了尾矿排放,提高了低品位热液蚀变型锂矿的综合利用水平。

玄武岩微筋对磷酸镁修补砂浆弯曲性能的增强增韧效应研究

为了探究玄武岩微筋(Basalt minibar)对磷酸镁修补砂浆(MPCRM)的增强增韧改性效果,通过四点弯曲试验分析纤维类型、纤维掺量、基体水胶比及养护条件对MPCRM弯拉强度和弯曲韧性的影响规律。试验结果表明:玄武岩微筋对MPCRM的弯曲增强增韧性能优越,且其增韧效果优于玄武岩单丝纤维;当玄武岩微筋掺量不低于1.0%(体积分数)时,MPCRM弯拉强度和弯曲韧性均随着玄武岩微筋掺量增加而提高;随着水胶比提高,玄武岩微筋增强MPCRM的弯曲韧性降低,弯拉强度先增加后减小,水胶比为0.18和体积掺量为1.5%的玄武岩微筋增强MPCRM的弯拉强度最大;掺入玄武岩微筋能够部分弥补低温养护MPCRM的受冻损伤。

寒区低温环境下泡沫沥青冷再生混合料性能研究

我国西藏、青海等省区全年气候寒冷,平均气温低,昼夜温差和年温差大,冻融循环频繁,公路建设普遍面临着生态环境脆弱、建筑材料数量匮乏且质量较差等问题。针对上述寒区气候特点,采用5℃、10℃、22℃、40℃、60℃和110℃分别模拟低温、室温、中温和高温养生条件下泡沫沥青冷再生混合料现场养生条件,基于室内试验分析了寒区低温环境温度对泡沫沥青冷再生混合料力学性能、路用性能、耐久性能的劣化影响;进而基于数字图像处理技术和工业CT无损检测技术,探讨了养生温度对泡沫沥青冷再生混合料内部泡沫沥青分散性状及微细观空隙结构的影响规律。结果表明:随着养生温度升高,泡沫沥青冷再生混合料的单轴贯入强度、无侧限抗压强度、动态回弹模量等力学指标均呈指数函数关系增大;相较于标准养生条件,在低温条件下拌和、养生的泡沫沥青冷再生混合料,其高温稳定性、抗反射裂缝性能及抗疲劳性能下降明显,并且环境温度越低,泡沫沥青冷再生混合料的综合路用性能降低幅值越大。升高养生温度后,泡沫沥青在破坏试件界面的分散面积增大,微细观空隙直径减小,并且微细观空隙结构中体积小于0.05 mm3的空隙占比增大。养生温度对泡沫沥青冷再生混合料的作用机理主要在于提高养生温度对泡沫沥青分散性状的促增作用和微细观空隙结构的细化作用。建议在泡沫沥青冷再生路面施工期间加强施工和养生期间的温度控制,并且结合寒区施工季节温度调整室内配合比设计养生温度。本研究成果可为泡沫沥青冷再生技术在寒区的推广应用提供借鉴。

低温固化聚酯粉末涂料的研究与应用

以热固性聚酯粉末涂料为研究对象,介绍了成膜物质中聚酯树脂和固化剂的特性及其在粉末涂料中的作用,并从制备、固化机理、改性、应用4个方面综述低温固化聚酯粉末涂料的研究进展。为改善聚酯粉末涂料出现缩孔的问题,将活性官能团丙烯酸酯引入聚酯树脂中进行表面改性,得到聚酯/丙烯酸混合型粉末涂料,并对耐候性聚酯/丙烯酸粉末涂料的耐候性及固化反应原理进行概述。为降低粉末涂料的固化温度,使其符合低温固化的发展要求,针对合成聚酯粉末涂料成膜物质的相对特性,在树脂合成过程中引入环氧型官能团作为功能单体或直接与环氧树脂混合。聚酯粉末涂料已在家具、汽车及家用电器领域得到广泛应用。未来,聚酯粉末涂料朝着节能环保、多样性和更广泛的适用性发展。

不同药剂引发对烤烟种子萌发和幼苗低温响应的影响

为更好地提高烟草催芽种子质量,提升幼苗素质培育壮苗,以中烟100和中川208为试验材料,研究了不同浓度的赤霉素(GA3)和生防菌剂“海益农”浸种引发处理对种子发芽势、发芽率、发芽指数、幼苗最长根长、最大叶面积、幼苗根干(鲜)质量、地上部分干(鲜)质量、抗氧化酶及丙二醛等指标的影响。结果表明,赤霉素对中烟100和中川208浸种引发的最适浓度分别是100 mg/L和50 mg/L,而“海益农”浸种引发的最适浓度则分别是2 g/L和1 g/L。赤霉素和“海益农”的大多数处理对两个烟草品种幼苗的生长都具有显著促进作用。采用隶属函数法对种子萌发指标和幼苗生长指标进行综合评价,从促进种子萌发和培育壮苗的角度,对中烟100促进作用最好的处理为赤霉素200 mg/L,其次为“海益农”1 g/L;而对中川208促进作用最好的处理为“海益农”1 g/L,其次为“海益农”20 g/L。对低温胁迫下幼苗叶片MDA和抗氧化酶活性的综合评价结果表明,提高中烟100耐冷能力的最好处理为“海益农”2 g/L,其次为赤霉素100 mg/L;提高中川208耐冷能力的最好处理为赤霉素100 mg/L,其次为“海益农”8 g/L。综上,不同烟草品种种子萌发、幼苗提壮和抗冷害效果达到最佳时,所使用的引发药剂种类和浓度不同,在生产中需要根据实际情况灵活选择使用。

低温养护对环氧树脂基砂浆早期性能的影响及机理

环氧树脂基砂浆是一种快速修补材料,为研究低温养护条件对环氧树脂基砂浆工作性能及早期力学性能的影响,构建了全过程低温环境,分别进行了抗压强度、抗折强度、流动度、凝结时间以及内部温度测试,分析了环氧树脂基砂浆的微观结构。结果表明:环氧树脂基砂浆性能受养护温度影响较大,当养护温度为0℃时,流动度仅为112 mm,但随着温度升高流动度增长较快;低温养护使得砂浆内部热效应减弱,延缓了凝结时间;早期强度也损失显著,0℃时,砂浆养护1 d才形成强度,说明低温环境大大减慢了体系的固化速度。微观分析表明低温养护导致砂浆内部结构疏松,裂缝及孔隙增多,说明固化反应不完全,从而降低了砂浆的性能。当养护温度为20℃时,砂浆内部结构较为致密,宏观结构也表现出较高强度。

猪精液保存技术研究进展

随着社会经济发展的需要,养猪业逐渐趋向规模化、集约化及高效化养殖。人工授精(AI)作为现代化猪养殖过程中最有效的一种生物技术被广泛应用,其中保存优质种猪精液是人工授精的关键步骤。经保存后的猪精液品质直接影响到母猪的受胎率及仔猪的成活率,在精液保存过程中其质量会受到温度、pH、微生物及精液稀释剂等因素影响。目前生产实践中对猪精液保存主要采用常温保存、低温保存、冷冻保存3种方法。常温保存为利用猪精液在15~25℃下产生酸性代谢产物形成酸抑制达到短期保存目的。低温保存为在抗冷剂的保护下将精液缓慢降温至0~5℃,使精子处于半休眠状态从而进行保存。冷冻保存为利用液氮等冷源使猪精液进行快速降温至―196~―79℃,从而抑制精子的生理代谢活动,以达到长期保存猪精液的目的。作者旨在对3种猪精液保存方法进行综述,对影响猪精液保存效果的主要因素进行简要介绍,并提出了针对不同猪精液保存方法的改进策略,从而为中国生猪产业的人工授精技术相关研究及其应用和猪种质资源保存提供有益的参考与借鉴,助推中国猪产业持续健康发展。

养护温度对低pH值水泥基材料水化产物及微结构的影响

低pH值水泥基材料因其低pH值特性被广泛应用于深地质处置库的建设过程中,但其在深地质处置库中的长期服役过程少有研究报道。通过X射线衍射分析、热重分析和扫描电镜等测试,研究了低pH值水泥基材料在深地质处置环境中不同温度下的长期水化产物和微结构演变规律,结果表明:在50℃长期养护下,低pH值水泥基材料的水化产物仍然有钙矾石,可能是由于低pH值水泥基材料的孔隙溶液氢氧根浓度较低,提高了钙矾石的分解温度,导致其在50℃以上仍能长期稳定存在;养护温度越高,低pH值水泥基材料的结合水含量也越高;养护温度的升高,促使箔片状的C-S-H凝胶向细针状的C-S-H凝胶转变。

利用新型固化催化剂低温制备聚酰亚胺材料

分别以2-羟基哌啶、2,3,5-三甲基吡嗪、2-氨甲基吡啶、吡嗪、喹啉(QL)和异喹啉(IQL)为固化催化剂,对以3,3′,4,4′-联苯四酸二酐(BPDA)、3,3′,4,4′-二苯甲酮四酸二酐(BTDA)、均苯四甲酸二酐(PMDA)和4,4′-二氨基二苯醚(ODA)为单体制备的聚酰胺酸(PAA)进行低温亚胺化制备。利用傅里叶变换红外光谱分析(FTIR)、力学性能分析、热重分析(TG)、差示扫描量热分析(DSC)等探究了不同固化催化剂对PAA亚胺化反应的催化效果。结果表明:5种固化催化剂对PAA的亚胺化反应有一定的催化作用,2-羟基哌啶的催化效果最好,对聚酰亚胺(PI)热稳定性影响最小,能在190℃下亚胺化制备PI薄膜,亚胺化程度为95.99%,所得PI薄膜拉伸强度为122.08 MPa,能同时较好地保持PI薄膜的力学性能与热稳定性。

负性光敏聚酰亚胺的种类及研究进展

由于优异的综合性能,负性光敏聚酰亚胺已成为微电子领域不可或缺的材料,根据负性光敏聚酰亚胺结构和合成工艺的不同,总结了其主要种类和研究进展。随着微电子技术的高度集成化和扇出型晶圆级封装技术的发展,对负性光敏聚酰亚胺材料提出了更高的要求,如更低的介电常数、更低的热膨胀系数和更低的固化温度等。本文进一步介绍了负性光敏聚酰亚胺材料的不同改性方法及其微观作用机制,并对比分析了各类改性方法的优缺点,为高性能负性光敏聚酰亚胺材料的设计开发提供理论基础。