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1.
对水镁石、水菱镁石和斜方云石资源及其加工和应用进行了评述。包括上述资源的发展历史、化学组成和物性参数、资源储量和矿石品位、生产加工以及在不同领域(如镁质阻燃剂、中和剂、重金属离子脱除剂、镁肥、饲料添加剂等)的应用,并对它们的发展前景进行了展望。 相似文献
2.
The rapidly growing chemistry of the cations, radicals, and anions based on the group 14 elements heavier than carbon (Si, Ge, Sn, and Pb) is one of the most important organometallic fields. Recent developments in this research area moved such species from the class of short-lived reactive intermediates to the class of easily accessible, isolable, and fully characterizable compounds. In this Account, we deal with the major accomplishments in the field of the stable representatives of "heavy" cations, radicals, and anions. 相似文献
3.
Douhal A 《Accounts of chemical research》2004,37(6):349-355
In this Account, we recount on our studies of 1'-hydroxy-2'-acetonaphthone (HAN, a proton transfer prototype molecule) in gas, solutions, and nanocavities. The internal H-bond photoreaction in HAN leads to a keto type structure, and following its formation, an internal twisting motion gives birth to keto rotamers. Theory, temperature, and solvent effects on its photodynamics show the involvement of efficient radiationless processes in both keto structures. When HAN is caged in a cyclodextrin nanocavity, the spectroscopy, photodynamics, and issues of twisting motion are strongly affected and could be tuned: a behavior relevant to those of many chemical and biological systems. 相似文献
4.
Thermoplastic processing,rheology, and extrudate properties of wheat,soy, and pea proteins
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Plant protein isolates (wheat gluten, soy, and pea protein) were treated in a thermoplastic extrusion process, yielding protein based bioplastic material. The application of glycerol as plasticizer in amounts of 50–67% of total mass and high temperatures above 140°C led to smooth and homogeneous extrudates. Viscosity measurements of the protein melt under extrusion conditions confirmed the thermoplastic behavior, obeying the power law with power law indices of 0.31‐0.4. Chemical changes in the material were qualitatively shown by amino acid analysis and fluorescence measurement. High moisture sensitivity and low mechanical stability of the extrudates, as determined by solubility, water vapor permeability, sorption isotherms, and tensile strength, can be partially ascribed to the high glycerol content. The application of pure protein bioplastics for technical purposes, e.g., as packing material, is discussed on basis of the presented data considering stability, appearance, and long time storage. POLYM. ENG. SCI., 55:1912–1919, 2015. © 2014 Society of Plastics Engineers 相似文献
5.
Margaret M. Braasch-Turi Jordan T. Koehn Debbie C. Crans 《International journal of molecular sciences》2022,23(21)
Lipoquinones are the topic of this review and are a class of hydrophobic lipid molecules with key biological functions that are linked to their structure, properties, and location within a biological membrane. Ubiquinones, plastoquinones, and menaquinones vary regarding their quinone headgroup, isoprenoid sidechain, properties, and biological functions, including the shuttling of electrons between membrane-bound protein complexes within the electron transport chain. Lipoquinones are highly hydrophobic molecules that are soluble in organic solvents and insoluble in aqueous solution, causing obstacles in water-based assays that measure their chemical properties, enzyme activities and effects on cell growth. Little is known about the location and ultimately movement of lipoquinones in the membrane, and these properties are topics described in this review. Computational studies are particularly abundant in the recent years in this area, and there is far less experimental evidence to verify the often conflicting interpretations and conclusions that result from computational studies of very different membrane model systems. Some recent experimental studies have described using truncated lipoquinone derivatives, such as ubiquinone-2 (UQ-2) and menaquinone-2 (MK-2), to investigate their conformation, their location in the membrane, and their biological function. Truncated lipoquinone derivatives are soluble in water-based assays, and hence can serve as excellent analogs for study even though they are more mobile in the membrane than the longer chain counterparts. In this review, we will discuss the properties, location in the membrane, and syntheses of three main classes of lipoquinones including truncated derivatives. Our goal is to highlight the importance of bridging the gap between experimental and computational methods and to incorporate properties-focused considerations when proposing future studies relating to the function of lipoquinones in membranes. 相似文献
6.
7.
Structural, rheological, and mechanical properties of ternary blends of a liquid crystalline copolyester (LCP) composed of p-hydroxybenzoic acid and 2,6-hydroxynaphthoic acid, poly(ehtylene naphthalate)(PEN), and poly(ethylene terephtalate) (PET) were investigated using capillary rheometry, tensile testing, scanning electron microscopy, and X-ray diffraction. Viscosity-shear rate behavior of the ternary blends is very similar to that of pure polymers and their binary blends. The activation energy of flows of the ternary blends was smaller than those of PEN and PET. Tensile modulus and strength of extruded strands of the blends increased with increasing LCP content. The extruded strands of the blends consist of a crystalline and oriented LCP phase and an amorphous and unoriented PEN/PET blended phase. Tensile mechanical properties and structures of the ternary blends were discussed. 相似文献
8.
J. P. Galloway 《Journal of the American Oil Chemists' Society》1976,53(6):271-274
Techniques and equipment for cleaning, cracking, dehulling, decorticating, and flaking of oil-bearing materials are described.
Particular methods and cautions for unusual materials are discussed. 相似文献
9.
The alkali elements in a wide range of glass and feldspar ore compositions can be rapidly determined with the flame spectrophotometer without making chemical separations. Flame photometer response to lithium, sodium, and potassium seems little affected by the presence of many of the glass constituents in concentration ranges commonly found in commercial glasses. The mean deviation in absolute per cent between chemical and flame photometer analyses for a series of twenty-nine glass and ore samples is approximately 0.15% for each of the three common alkalis lithium, sodium, and potassium. Evaluation of the rubidium and cesium results was not possible since chemical analyses for these elements were not available. 相似文献
10.
M.A. Natal-Santiago S.G. Podkolzin R.D. Cortright J.A. Dumesic 《Catalysis Letters》1997,45(3-4):155-163
Microcalorimetric measurements were made of the interaction of hydrogen, ethene, isobutene and isobutane at 300 K with silica-
supported Pt, Pd, and PtSn catalysts. The initial heats of hydrogen adsorption on silica-supported Pd and Pt are 104 and 95
kJ/mol, respectively. The presence of Sn decreases the saturation uptake of hydrogen on the PtSn sample. The initial heats
of ethene interaction with Pd/silica and Pt/silica are 170 and 145 kJ/mol, respectively. The presence of Sn decreases the
initial heat to 115 kJ/mol on the PtSn sample. The initial heats of isobutene interaction with silica-supported Pd and Pt
are 160 and 190 kJ/mol, respectively. The presence of Sn decreases the initial heat to 125 kJ/mol on the PtSn sample. It appears
that ethene and isobutene adsorb dissociatively on silica-supported Pd and Pt to form alkylidyne species at 300 K, with an
average strength of carbon-metal bonds for these species near 230 kJ/mol. Ethene and isobutene adsorb on silica-supported
PtSn to form di- σ- and π-bonded alkene species at 300 K, with an average strength of carbon-metal bonds for these species
near 190 and 130 kJ/mol, respectively. Isobutane appears to adsorb dissociatively on a small number of sites on silica-supported
Pd and Pt, and this dissociation is also inhibited by Sn on PtSn samples.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
11.
Seong H. Kim Christopher M. Lee Kabindra Kafle 《Korean Journal of Chemical Engineering》2013,30(12):2127-2141
Cellulose is among the most important and abundant biopolymers in biosphere. It is the main structural component of a vast number of plants that carries vital functions for plant growth. Cellulose-based materials have been used in a variety of human activities ranging from papers and fabrics to engineering applications including production of biofuels. However, our understanding of the cellulose structure in its native form is quite limited because the current experimental methods often require separation or purification processes and provide only partial information of the cellulose structure. This paper aims at providing a brief background of the cellulose structure and reviewing the basic principles, capabilities and limitations of the cellulose characterization methods that are widely used by engineers dealing with biomass. The analytical techniques covered in this paper include x-ray diffraction, nuclear magnetic resonance, and vibrational spectroscopy (infrared, Raman, and sum-frequency-generation). The scope of the paper is restricted to the application of these techniques to the structural analysis of cellulose. 相似文献
12.
This study describes the preparation of blends between an amorphous polymer (PVC) and a crystalline polymer (PEO), with a third polymeric part that presents electronic conduction capacity (PEDOT‐PSS). Binary (PEO/PVC, PEO/PEDOT‐PSS, PVC/PEDOT‐PSS) and ternary (PVC/PEO/PEDOT‐PSS) blends were prepared by changing the concentrations of the constituents and were analyzed by electronic conductivity, Raman spatial resolution, infrared spectroscopies, and thermogravimetric analysis. The Raman and FTIR analyses showed the incorporation of PEDOT‐PSS within the blends. The higher conductivity presented by the ternary blend was 8.6 × 10?6 Scm?1, composed of 24% of PVC, 16% of PEO, and 60% of PEDOT‐PSS. For binary blends the conductivity was proportional to the PEDOT‐PSS content. The thermal stability could be observed through the TG curves of the blends that presented an increase of 19 K in the weight loss temperature at the 10% level when compared to the pure components. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1710–1715, 2005 相似文献
13.
In this study, the novel halogen‐free flame retardants (PSiN, A and B), which contain phosphorus, nitrogen, and silicon, have been synthesized. The structure of PSiN‐A is characterized by fourier transform infrared spectroscopy and proton nuclear magnetic resonance, and its thermal property is studied through thermo gravimetric analysis (TGA). PSiN‐A and B were blended with polypropylene(PP) to obtain PP/PSiN composites. The flame‐retardant properties of PP/PSiN composites are estimated by Limiting Oxygen Index (LOI) values, and their degradation behaviors are investigated through TGA, under nitrogen from room temperature to 800°C. The fire performance of PP is improved by PSiN(A or B): the LOI value of PP/PSiN‐A reach 26.0 vol% and the char yield is at 27 wt% at 800°C. The phosphorus in PSiN provides possibility for the PP blends to form char, and the silicon improves the thermal stability of char. The active energies of PSiN and PP are calculated through the method of Horowitz–Metzger. POLYM. ENG. SCI. 46:344–350, 2006. © 2006 Society of Plastics Engineers 相似文献
14.
Weanling rats were fed on diets of rice/beans (RB) with or without mineral (M) supplement; vitamin A (A); M + A (MA); or milk (L), containing from 3 to 14% protein. As determined by various measures, the best results were observed in the group fed the RB diet, supplemented with L. This group was followed by those receiving the MA and M diets. Protein utilization in the RB diet, as well as minimum protein requirement for maintaining body weight, depend on the supplementary nutrients. The mechanism of this effect may be related to the appetite of the animals and to the voluntary intake, which is influenced and regulated by the diet composition. 相似文献
15.
Te-Sheng Chang 《International journal of molecular sciences》2014,15(4):5699-5716
Daidzein and genistein are two major components of soy isoflavones. They exist abundantly in plants and possess multiple bioactivities. In contrast, ortho-hydroxydaidzein (OHD) and ortho-hydroxygenistein (OHG), including 6-hydroxydaidzein (6-OHD), 8-hydroxydaidzein (8-OHD), 3′-hydroxydaidzein (3′-OHD), 6-hydroxygenistein (6-OHG), 8-hydroxygenistein (8-OHG), and 3′-hydroxygenistein (3′-OHG), are rarely found in plants. Instead, they are usually isolated from fermented soybean foods or microbial fermentation broth feeding with soybean meal. Accordingly, the bioactivity of OHD and OHG has been investigated less compared to that of soy isoflavones. Recently, OHD and OHG were produced by genetically engineering microorganisms through gene cloning of cytochrome P450 (CYP) enzyme systems. This success opens up bioactivity investigation and industrial applications of OHD and OHG in the future. This article reviews isolation of OHD and OHG from non-synthetic sources and production of the compounds by genetically modified microorganisms. Several bioactivities, such as anticancer and antimelanogenesis-related activities, of OHD and OHG, are also discussed. 相似文献
16.
Richard Sasin Frederick R. Longo Francis A. Carey Charles M. Paulson Jr. George S. Sasin 《Journal of the American Oil Chemists' Society》1960,37(3):152-153
Summary
p-Bromo-,m-nitro-,p-nitrobenzenesulfonamides,p-toluenesulfonamides,p-tolyl-, anda-naphthylureas, and 3-nitrophthalimide derivatives of pentyl-, hexyl-, heptyl-, octyl-, and decylamines were prepared.m-Nitrobenzenesulfonamides,p-nitrobenzensulfonamides, andp-tolylureas appear to be the most satisfactory derivatives for the identification of these amines.
Taken from senior theses submitted by Francis A. Carey and Charles M. Paulson. 相似文献
17.
Blending,chilling, and tempering of margarines and shortenings 总被引:1,自引:0,他引:1
A. J. Haighton 《Journal of the American Oil Chemists' Society》1976,53(6):397-399
The preparation of the milk and fat phase of margarine, which is a milk-in-fat emulsion, is discussed. Refined and deodorized
fats are blended to meet constraints in regard to price, solid fat index, taste stability, and crystallization behavior. The
milk phase is prepared according to specifications and concerning protein content, salt concentration, and other ingredients,
and adjusted to the pH. The flavored fat and the milk are then dosed in the proper ratio and processed by means of scraped
coolers in which the mixture is emulsified, cooled, and crystallized. High speed machines pack the product in tubs or wrappers.
The processing of shortenings is roughly the same, but no water phase is used. Occasionally, tempering, which is a hold of
several hours at elevated temperature, is applied to improve the plasticity of the product, its creaming properties, and overall
baking performance. 相似文献
18.
The discovery of the striking catalytic properties of the Mobil zeolite ZSM-5 has been followed by a large and intensive research effort both in catalysis promoted by ZSM-5 and in the synthesis and properties of other highly siliceous zeolites. While the distinctions between ZSM-5 and some of the claimed new zeolites are barely perceptible (it would perhaps be invidious to name these zeolites), other new. highly-siliceous zeolites differ markedly from ZSM-5/ZSM-11 in structure and consequently in other properties as well. Zeolites Nu-1 and FU-1 have now been fairly well characterized in both physical and catalytic properties. Although their crystal structures have not yet been determined, it is clear that they are different from ZSM-5 (and indeed, any other published zeolite structure). 相似文献
19.
In principle, the oil milling process is straightforward. The wide variety of equipment in use reflects, however, a multiparametric
process. The main limiting parameters are kind of seed, oil content, particle strength, particle structure, temperature, moisture,
particle size, residence time, mechanical forces, etc. Additionally, the seed specific parameters vary not only between kinds
of seed but also for the same seed, due to different conditions in climate, soil, and harvesting. Therefore, equipment design
must be widely based on statistical averages of the limiting parameters. In other words, exact precalculation of the single
technological steps is impossible. As a consequence, for more than 5,000 years, the oil milling process has been in the stage
of being optimized. The acutal technical standard is very satisfying, but there is still a strong need for further research
and development. Currently, as in the past, the oil milling process seems to be not so much a science as an art. 相似文献
20.
X-ray, optical, and chemical data are presented for sillimanites and for a wide range of natural and synthetic mullites. Single-crystal X-ray studies have revealed a new type of mullite (called S mullite) characterized by subsidiary sharp reflections in distinction to the extra diffuse reflections of common mullite (called D mullite). Atomic substitution of aluminum in D mullite leads to expansion of a and c but not of b, whereas substitution of iron and titanium in natural mullites gives a slight initial decrease in a and b followed by a subsequent increase; c increases uniformly for all concentrations. The data are consistent with solid solution ranging between the extremes 3Al2 O3 .2SiO2 , 2Al2 O3 .-SiO2 , and 3(Al0.9 Fe0.1 )2 O3 .2SiO2 . Cell dimensions of sillimanite vary only slightly. Consideration of the various methods of distinguishing mullite and sillimanite shows that the measurement of cell dimensions is the most reliable and for mullite has the added advantage that the S and D polymorphs may be distinguished and an estimate of the composition obtained for D mullite. 相似文献