Theoretical and experimental assessment of a novel method to establish the complete measurement range of the calorimeter and its limit of detection and quantification

For determining the accuracy of a calorimeter over the instrument’s entire measuring range, a novel method has been established. For this new approach, (a) benzoic acid (C₆H₅CO₂H) as a certified reference material (CRM), (b) SiO₂ and (c) a mixture of CRM benzoic acid and SiO₂ have been used. To illustrate the essential difference between 1) the novel analytical method for control of the entire measurement range and 2) the calorimeter calibration, both applications of benzoic acid (BA) have been demonstrated. An experimental result showed that BA was successfully used to check the whole calorimeter measurement range. The results also showed that the same new method was successfully applied to determine the limit of detection and quantification. A new instrument testing process and a new measurement technique have thus been established. In this way, the cost of using CRM to control the accuracy of measuring the entire measuring range of the calorimeter, as shown in this paper, is minimized. The requirements of the ISO/IEC 17025:2017 standard are satisfied. ISO/IEC 17025:2017, together with ISO 9001:2015 (quality management systems), ISO 14001:2015 (relate to environmental protection) and ISO 45001:2018 (occupational safety), constitute an integrated quality system by which a testing laboratory may also accredit.     

AlCl3·6H2O在盐酸体系中的结晶行为

研究了AlCl₃·6H₂O在盐酸体系中的结晶行为,考察了铁、钙、镁、钾、钠等杂质对AlCl₃·6H₂O结晶行为的影响,并利用聚焦光束反射测量技术（FBRM）和颗粒录影显微镜（PVM）探讨了不同盐酸滴加速度下AlCl₃·6H₂O的结晶粒度分布及形貌。结果表明,AlCl₃·6H₂O的结晶量随着盐酸加入量的增加而增加,当浓盐酸加入量为AlCl₃饱和溶液体积的2.25倍时,25℃时的结晶效率可达到80%。溶液中Fe的存在可促进AlCl₃·6H₂O的结晶,在1.5 mol·kg^-1的AlCl₃溶液中,当铝铁摩尔比低于3：1时,得到的AlCl₃·6H₂O晶体中铁的含量小于0.1%。钾、钙、镁、钠等杂质对AlCl₃·6H₂O的结晶影响不大。盐酸添加速度影响AlCl₃·6H₂O的形貌,快的盐酸添加速度易使晶体发生团聚,颗粒粒径小,盐酸添加速度较慢时,可得到颗粒较大、形貌好的单晶。     

Effect of a promoter on the methanation activity of a Mo-based sulfur-resistant catalyst

The effect of adding Co, Ni or La on the methanation activity of a Mo-based sulfur-resistant catalyst was investigated. As promoters, Co, Ni and La all improved the methanation activity of a 15% MoO₃/Al₂O₃ catalyst but to different extents. Similar improvements were also found when Co, Ni or La was added to a 15% MoO₃/25%-CeO₂-Al₂O₃ catalyst. The promotion effects of Co and Ni were better than that of La. However, the catalytic methanation activity deteriorated the most with time for the Ni-promoted catalyst. The used catalysts were analyzed by nitrogen adsorption measurement, X-ray diffraction and X-ray photoelectron spectroscopy.     

Emission Analysis of Pr3 +& Tm3 +: B2O3-BaO-LiF/AlF3 Glasses

We report here on the preparation and emission properties of Pr³⁺(4f²) and Tm³⁺ (4f¹²) ions doped in newly developed to transparent glassy matrices of BBLi (= B₂O₃-BaO-LiF) BBAl (= B₂O₃-BaO-AlF₃). Under an UV source (355 nm), both the Tm³⁺: BBLi and Tm^{3 +}: BBAl glasses have shown bright blue emission at 452 nm. With regard to both the Pr³⁺: BBL and Pr³⁺: BBAl glasses red emission have been noticed upon excitation with blue excitation wavelength (445 nm).These results have also been obtained from the measurement of their emission spectra. For such emission bands, decay curves have been recorded to obtain their lifetimes. We have prepared optical glasses with good transparency and stability. From the measurement of XRD spectra, amorphous nature of these glasses have been confirmed. Between the two glasses studied, glass containing Li has demonstrated an extended UV transmission and also it has revealed an improved NIR transmission ability compared to the other glass with LiF.     

添加纳米MgO和SiO2颗粒对二元碳酸盐(Li2CO3-K2CO3)比热容的影响

熔盐作为一种新型传热工质,由于其液体使用范围宽,比热容相对较高,蓄热能力强,已被广泛应用于聚热太阳能电站的储热传热介质,而通过增强熔盐的比热容可以显著提高其储热密度。将纳米SiO₂和MgO颗粒分别均匀分散到二元共晶碳酸盐（Li₂CO₃-K₂CO₃）中,制备出两种稳定的纳米流体,采用差式扫描量热法（DSC）分析纳米颗粒对熔盐比热容的影响。实验结果显示,添加20 nm的纳米颗粒对碳酸盐的比热容有显著影响：通过添加纳米MgO和SiO₂颗粒,纳米熔盐比热容相比基盐分别平均提高了27.5%～34.1%,11%～20.7%。经过多个固-液循环后,测得两种纳米流体的比热容变化率均低于4.31%,且具有良好的热稳定性。采用电子扫描显微镜表征纳米流体的微观结构,纳米流体在固态时的SEM图像显示在熔盐表面形成了特殊的纳米结构。     

层层组装晶种法制备Mg-MOF-74膜及其分离性能

以2,5-二羟基对苯二甲酸和乙酸镁溶液为原料通过交替浸渍层层组装法在a-Al₂O₃载体表面预置晶种层, 再利用二次生长法制备出连续而致密的Mg-MOF-74晶体膜。采用X射线衍射(XRD)和扫描电镜(SEM)对膜进行了表征。实验结果表明:相比于原位溶剂热合成法, 通过2, 5-二羟基对苯二甲酸和乙酸镁交替浸渍层层组装法可以增强Mg-MOF-74与氧化铝基体之间的附着效果, 提高晶体薄膜的致密性与连续性, 实验发现4次交替浸渍层层组装预置晶种可以制备出具有分子筛分性能的Mg-MOF-74晶体膜, 单组分气体渗透测试表明其H₂/CO₂的理想选择性可以达到8.96, 高于其努森扩散选择性。XRD测试表明该晶体膜的特征衍射峰与文献报告的粉末MOF-74完全一致, 表明Mg-MOF-74晶粒以无取向形式生长于氧化铝载体表面。SEM表征表明Mg-MOF-74晶粒呈麦粒状微观外形, 其BET比表面积可以达到1182 m²·g^-1。     

层层组装晶种法制备Mg-MOF-74膜及其分离性能

以2,5-二羟基对苯二甲酸和乙酸镁溶液为原料通过交替浸渍层层组装法在a-Al₂O₃载体表面预置晶种层, 再利用二次生长法制备出连续而致密的Mg-MOF-74晶体膜。采用X射线衍射(XRD)和扫描电镜(SEM)对膜进行了表征。实验结果表明:相比于原位溶剂热合成法, 通过2, 5-二羟基对苯二甲酸和乙酸镁交替浸渍层层组装法可以增强Mg-MOF-74与氧化铝基体之间的附着效果, 提高晶体薄膜的致密性与连续性, 实验发现4次交替浸渍层层组装预置晶种可以制备出具有分子筛分性能的Mg-MOF-74晶体膜, 单组分气体渗透测试表明其H₂/CO₂的理想选择性可以达到8.96, 高于其努森扩散选择性。XRD测试表明该晶体膜的特征衍射峰与文献报告的粉末MOF-74完全一致, 表明Mg-MOF-74晶粒以无取向形式生长于氧化铝载体表面。SEM表征表明Mg-MOF-74晶粒呈麦粒状微观外形, 其BET比表面积可以达到1182 m²·g^-1。     

Experimental investigation of the light extinction method for measuring aerosol size distributions

The independent and the dependent models of light extinction methods were two new methods for measuring the particle size distribution. Some experiments were carried out to confirm these methods. The experimental results of the measurement of latex particles ranged from 0.091 to 9.85 μm and some samples of TiO₂ powder were presented. Experimental results have shown that these methods have a larger measurable range from about 0.01 to 10 μm, high accuracy and a short measurement time. The optimum value of I/I₀ in the measurement should lie between 0.4 and 0.9. The independent model of light extinction method can even measure ‘multi-peaks’ polydisperse aerosols.     

熔剂化学组成对陶瓷薄板坯体断裂模数影响的探究

陶瓷薄板作为一种新型建筑装饰材料,其配方和工艺技术应用方面还需不断提升,陶瓷研究者们也一直致力于陶瓷薄板的探究。笔者通过对K₂O(Na₂O)-SiO₂-Al₂O₃体系配方中不同化学组成熔剂对陶瓷薄板坯体烧后机械强度的影响研究,开发出一种断裂模数达94.77 MPa的陶瓷薄板坯体配方。     

Breakage behaviour of enzyme granules in a repeated impact test

In many industries, handling or processing of relatively fragile particles takes place and predictions are required whether a significant proportion of the particles will be damaged. These processes have been designed and controlled solely on the basis of particle size and shape. Another parameter that needs to be introduced is particle strength. The stringent environmental laws demand improved particle mechanical quality, which has given rise to the need for a more accurate and fundamental particle strength measurement and its application in modelling and control of particulate processes. Particles need to show good resistance against static and dynamic loads.

The present paper deals with the study of breakage behaviour of different enzyme granules subjected to repeated impacts using a new instrument developed at the Delft University of Technology. The impact test involves bombarding the particles against a flat target repeatedly. The main feature of this new test is its ability to impact a large number of particles against a flat target repeatedly, and generate extremely reproducible results. Testing a large number of particles has the advantage of producing statistically correct results. The repeated impacts provide information on the breakage behaviour of the particles based on their history. In the new impact test enzyme granules can undergo very low impact velocities of the order of 5 m s⁻¹. These low impact velocities lead to attrition and chipping of the granules.

The current paper presents preliminary results on the breakage behaviour of the new impact test and its basic advantages over already existing tests. Furthermore, experiments were performed on enzyme granules, and the breakage mechanisms determined, depending on the change in size and shape of the particles.     

VAMAS Round Robin on Fracture Toughness of Silicon Nitride

Eight laboratories in Germany, Japan, U.K., and U.S. participated in the VAMAS round robin. The fracture toughness of silicon nitride at room temperature and at 1200^deg;C was measured by three methods: the single-edge V-notched beam (SEVNB), single-edge precracked beam (SEPB), and chevron notched beam (CNB). The obtained values show hardly any crosshead speed dependence, irrespective of test temperature and atmosphere. Results may have been influenced by a small amount of slow crack growth, but distinct R -curve behavior could not be detected within the scope of the tests. The values at 1200^deg;C in N₂ can be measured by the SEVNB and SEPB methods with small scatters. The oxidation of silicon nitride, caused by heating in air, increases the SEVNB and SEPB values. The CNB values are free from the effects of test temperature and atmosphere, but they show a large scatter between laboratories. However, the chevron V-notched beam (CVNB) method, which is an improved CNB method, shows values with a small scatter, irrespective of the measurement conditions. The SEVNB and SEPB measurements in N₂ and the CVNB measurement under any conditions are recommended for the measurement of high-temperature fracture toughness.     

Growth of Pb((Zn1/3Nb2/3)0.91Ti0.09)O3 Single Crystals Using an Allomeric Seed Crystal and Their Electrical Properties

Single crystals of Pb((Zn_1/3Nb_2/3)_0.91Ti_0.09)O₃ (PZNT 91/9), 28 mm in diameter and 30 mm in length, have been successfully grown using a modified Bridgman technique with an allomeric seed crystal. X-ray fluorescence analysis (XRFA) measurement confirms that the effect of segregation is not serious. The segregation coefficient k for PbTiO₃ content during crystal growth is 0.99, which causes some fluctuation in the composition along the growth direction. The fluctuation of composition and the complicated domain structure cause a variation of electric properties. Dielectric measurement indicates that PZNT 91/9 crystals exhibit an almost normal ferroelectric phase transition at ∼183°C from the tetragonal phase to the cubic phase. In addition, a weak frequency-dependent ferroelectric-ferroelectric phase transition is observed at ∼85°C, which is attributed to partial conversion of the rhombohedral phase to a tetragonal phase. The dielectric thermal hysteresis behavior and the existence of polarization above the Curie temperature verify that the phase transitions at ∼85° and 183°C are first order with a slight diffuse character and first order, respectively. It is demonstrated that the effects of segregation can be decreased and the homogeneity of the obtained PZNT 91/9 single crystals can be improved by optimizing growth parameters.     

Temperature Dependence of the Cation Distribution in Nickel Aluminate Spinel from Thermodynamics and X-Rays

The single crystal NiAl₂O₄ was prepared by a solid-state reaction. The change of its cation distribution with temperature was calculated by a modified thermodynamic equation by including a new parameter δ, which is a characteristic of nonconfiguration entropy. The calculated results showed that the degree of inversion for NiAl₂O₄ decreases with temperature, although the temperature dependence of cation distribution is very weak. This result was supported by X-ray diffraction measurement.     

Electrochemical study of the quasi-binary thallium(I) telluride–indium(III) telluride solid system

The Tl₂Te–In₂Te₃ solid system was studied using emf measurement of concentration cells to verify the phase diagram for the system published earlier by other authors. Partial molar thermodynamic functions of thallium at 443 K were determined for the ternary phases of this system. The study produced substantial evidence corroborating the formation of a new compound not found earlier.     

Effect of Ionic Strength on the Stability of Binary Ceramic Suspensions

The colloidal stability of aqueous Al₂O₃/ZrO₂ and Al₂O₃/SiC suspensions in the presence of electrolyte was investigated by rheological measurement. It was observed that the stability of binary systems improved with increasing ionic strength, where the solution pH value was maintained in the middle range of the two isoelectric points of the constituent powders. In this case, the electrostatic attractive interaction between dissimilar particles became more prominent when their number ratio approached unity. In addition, the salt-dependent stability was studied over the entire range of pH and relative component fraction. The results showed that the role of ionic strength in promoting flocculation or stabilization of colloidal dispersions was mainly determined by the predominant electrostatic interaction between particles, and the experimental stability maps were used to distinguish the stable and unstable suspensions with the addition of an electrolyte.     

铈改性甲醇合成铜基催化剂的制备及其性能

采用反加共沉淀法,以硝酸铜、硝酸锌、硝酸铝溶液为原料,碳酸钠溶液为沉淀剂,硝酸铈为助剂,制备了铈（Ce）改性的甲醇合成铜基催化剂（CuZnAlCe）,并通过X射线衍射（XRD）、N₂等温吸附、热重-差热分析（TG-DTA）、扫描电子显微镜（SEM）、程序升温还原（TPR）等手段进行表征,采用微型固定床反应装置进行催化活性及稳定性评价,考察了Ce含量对CuZnAlCe催化剂结构和催化性能的影响。结果表明,Ce的引入可以改善催化剂活性中心的分散度,使催化剂比表面积增加,整体的结构变得更加松散,催化剂更容易被还原。随着Ce含量的增加,CO的转化率不断增大,当Ce含量为2%时CO转化率最大,可达47.6%。但Ce含量过量时使催化剂还原温度升高,CO的转化率降低。此外,适当的Ce含量改性可以提高铜基催化剂的热稳定性。     

Enhanced Magnetization of 3 mol% Yttria-Doped Zirconia/Barium Hexaferrite by Post-Plastic Deformation

A 3-mol%-Y₂O₃-doped tetragonal-ZrO₂ polycrystal/BaFe₁₂O₁₉ composite was fabricated by powder metallurgical processes, and its mechanical and magnetic properties were evaluated. Post-plastic deformation (i.e., hot-forging) on the composite improved its magnetic properties—that is, saturation magnetization and coercivity—probably because of the alignment of the hexaferrite platelet particles. Post-plastic deformation may represent a new process to complement conventional slurry-pressing under a magnetic field, for obtaining good magnetic properties in a magnetic-particle-dispersed composite.     

Elastic Constants of Tetragonal Zirconia Measured by a New Powder Diffraction Technique

Elastic constants for 12 mol% Ce-doped tetragonal zirconia have been determined from peak shifts in neutron diffraction patterns recorded under applied uniaxial stress. When these diffraction data are combined with a measured value of Young's modulus, a complete set of elastic constants is obtained. The values are c ₁₁= 327, c ₁₂= 100, c ₁₃= 62, c ₃₃= 264, c ₄₄= 59, and c ₆₆= 64 (units: GPa). These are the first reported results using a new technique for the measurement of elastic constants for anisotropic materials via neutron diffraction measurements on polycrystalline samples.     

Chemical Expansivity of Electrochemical Ceramics

To better understand thermal strain in electrochemical ceramics, the temperature and oxidation-state dependence of lattice volume in La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ (LSCF) were measured. Large values in the apparent thermal expansion coefficient at high temperature (>50 ppm/°C) were caused by changes in oxygen content, not increases in thermal expansivity. This material can be described using an improved thermodynamic formalism that incorporates a new physical property, the chemical expansivity . Our approach opens new avenues for modeling stress and strain in materials, probing defect structure, and analyzing transport and kinetic properties.     

Assessment of limitations and potentials for improvement in deep desulfurization through detailed kinetic analysis of mechanistic pathways

Utilizing an improved method for the assignment of the rate constants to the complicated network of reaction pathways in the hydrodesulfurization (HDS) of polyaromatic sulfur compounds (PASCs), new understanding has been obtained concerning the intrinsic limitations to achieving the new distillate fuels standards. Establishing the relative rates for hydrogenation of the parent sulfur compound and its desulfurized products, and considering thermodynamic limitations on hydrogenated intermediates are critical to these improved kinetics. With this new approach, it has been possible to more accurately assess the differences in performance of different catalysts such as Co–MoS_x/Al₂O₃, Ni–MoS_x/Al₂O₃ and analogous catalysts supported on carbons, the basic causes of selectivity change with temperature, and the mechanistic consequences of inhibitors on the HDS product distributions. Ni promoted catalysts were found to possess much higher hydrogenation activities than comparable Co promoted catalysts. Carbon supported catalysts appear to have potential for HDS at high temperatures. Inhibition by H₂S affects both hydrogenation and direct sulfur extraction HDS routes, but, secondary hydrogenation of desulfurized aromatic products was found to be the most sensitive to inhibition. Naphthalene inhibits all hydrogenation reactions but has little effect on direct HDS.