Transcytosis of alpha1-acidic glycoprotein in the continuous microvascular endothelium

By using perfusions and bolus administration, coupled with postembedding immunocytochemical procedures, we have identified the structures involved in the transport of derivatized orosomucoid (alpha1-acidic glycoprotein) across the continuous microvascular endothelium of the murine myocardium. Our findings indicate that: (i) monomeric orosomucoid binds to the luminal surface of the endothelium; (ii) it is restricted to caveolae during its transport across the endothelium; (iii) it is detected in the perivascular spaces at early time points (by 1 min) and in larger quantities at later time points (>5 min) from the beginning of its perfusion or its intravascular administration; (iv) no orosomucoid molecules are found in the intercellular junctions or at the abluminal exits of interendothelial spaces; and (v) the vesicular transport of orosomucoid is strongly inhibited by N-ethylmaleimide (>80%). Because, by size and shape, the orosomucoid qualifies as a preferential probe for the postulated small pore system, our results are discussed in relation to the pore theory of capillary permeability.     

Regulation of transport pathways in tumor vessels: role of tumor type and microenvironment

Novel anti-neoplastic agents such as gene targeting vectors and encapsulated carriers are quite large (approximately 100-300 nm in diameter). An understanding of the functional size and physiological regulation of transvascular pathways is necessary to optimize delivery of these agents. Here we analyze the functional limits of transvascular transport and its modulation by the microenvironment. One human and five murine tumors including mammary and colorectal carcinomas, hepatoma, glioma, and sarcoma were implanted in the dorsal skin-fold chamber or cranial window, and the pore cutoff size, a functional measure of transvascular gap size, was determined. The microenvironment was modulated: (i) spatially, by growing tumors in subcutaneous or cranial locations and (ii) temporally, by inducing vascular regression in hormone-dependent tumors. Tumors grown subcutaneously exhibited a characteristic pore cutoff size ranging from 200 nm to 1.2 microm. This pore cutoff size was reduced in tumors grown in the cranium or in regressing tumors after hormone withdrawal. Vessels induced in basic fibroblast growth factor-containing gels had a pore cutoff size of 200 nm. Albumin permeability was independent of pore cutoff size. These results have three major implications for the delivery of therapeutic agents: (i) delivery may be less efficient in cranial tumors than in subcutaneous tumors, (ii) delivery may be reduced during tumor regression induced by hormonal ablation, and (iii) permeability to a molecule is independent of pore cutoff size as long as the diameter of the molecule is much less than the pore diameter.     

New General Pore Size Distribution Model by Classical Thermodynamics Application: Activated Carbon

A model is developed using classical thermodynamics to characterize pore size distributions (PSDs) of materials containing micropores and mesopores. The thermal equation of equilibrium adsorption (TEEA) is used to provide thermodynamic properties and relate the relative pore filling pressure of vapors to the characteristic pore energies of the adsorbent/adsorbate system for micropore sizes. Pore characteristic energies are calculated by averaging of interaction energies between adsorbate molecules and adsorbent pore walls as well as considering adsorbate-adsorbate interactions. A modified Kelvin equation is used to characterize mesopore sizes by considering variation of the adsorbate surface tension and by excluding the adsorbed film layer for the pore size. The modified-Kelvin equation provides similar pore filling pressures as predicted by density functional theory. Combination of these models provides a complete PSD of the adsorbent for the micropores and mesopores. The resulting PSD is compared with the PSDs from Jaroniec and Choma and Horvath and Kawazoe models as well as a first-order approximation model using Polanyi theory. The major importance of this model is its basis on classical thermodynamic properties, less simplifying assumptions in its derivation compared to other methods, and ease of use.     

Present and future trends with NLP

A total of 60 cylindrical 6 x 6 mm samples of a macroporous biphasic calcium phosphate (MBCP) ceramic were implanted into a distal femoral site in 30 rabbits. These samples represented six kinds of implants with two different macropore diameters and three different macroporosity percentages. Analysis of backscattered electron images of implant surfaces analysed by a factorial design method showed that implants with 565 microm pore size provided more abundant newly formed bone both in peripheral and deep pores than those with 300 microm pore size. No significant differences were found between implants with 40 and 50% macroporosity, suggesting that the influence of macropore size on bone ingrowth was greater than that of macroporosity percentage. MBCP implants with 565 microm pore diameter and 40% macroporosity represented the optimal association for homogeneous and abundant bone ingrowth.     

Immunoglobulin E, viral antibodies and obstructive lung disease in adults. The relation between antibody level in serum, lung function and non-specific bronchial reactivity

The electrophoretic mobilities of DNA molecules in three different molecular weight ladders were measured in polyacrylamide gels containing different acrylamide concentrations (%T) and cross-linker ratios (%C), cast and run in Trisacetate-EDTA (TAE) buffer. The apparent pore radius of each gel was estimated from Ferguson plots of the relative mobilities of each of the DNA molecules, using the mobility of the monomer fragment in each molecular weight ladder as the reference mobility. The effective size of each of the DNA molecules was estimated from its radius of gyration. The apparent gel pore radii calculated in this manner ranged from 21 nm in gels containing 10.5%T, 5%C to 200 nm in gels with 4.6%T, 2%C, similar to the values observed for polyacrylamide gels cast and run in Tris-borate-EDTA (TBE) buffer (Holmes and Stellwagen, Electrophoresis 1991, 12, 612-619). Hence, the effective pore size of polyacrylamide gels is essentially independent of whether the gels are cast and run in TAE or TBE buffer.     

添加红柱石对高炉炭砖孔径分布与热导率影响

采用X射线衍射仪、压汞仪、激光导热仪、扫描电子显微镜和能谱分析仪等测试手段,研究了不同红柱石加入量的焙烧炭砖的孔径分布及热导率;并借助灰色关联理论分析了气孔孔径区间与炭砖热导率的相关性.结果表明:炭砖的气孔孔径分布受红柱石的分解和SiC生成量共同影响.其提高微孔化的机理是:引入的红柱石在1300℃开始原位分解可提高微孔...     

Structural characteristics of modified activated carbons and adsorption of explosives

Several series of activated carbons prepared by catalytic and noncatalytic gasification and subsequent deposition of pyrocarbon by pyrolysis of methylene chloride or n-amyl alcohol were studied by FTIR, chromatography, and adsorption methods using nitrogen and probe organics (explosives). The relationships between the textural characteristics of carbon samples and the recovery rates (eta) of explosives on solid-phase extraction (SPE) using different solvents for their elution after adsorption were analyzed using experimental and quantum chemical calculation results. The eta values for nitrate esters, cyclic nitroamines, and nitroaromatics only partially correlate with different adsorbent parameters (characterizing microporosity, mesoporosity, pore size distributions, etc.), polarity of eluting solvents, or characteristics of probe molecules, since there are many factors strongly affecting the recovery rates. Some of the synthesized carbons provide higher eta values than those for such commercial adsorbents as Hypercarb and Envicarb.     

纳米尺度孔隙内气体导热系数的分子动力学模拟

应用Lennard-Jone作用势,在300K和0.1MPa条件下,对边长20nm的立方体孔隙内氮气的导热系数进行了平衡分子动力学模拟.结果得出分子分速度和速率的分布与统计力学得到的Maxwell速度和速率分布曲线基本一致,并且分子的平均自由程受到孔隙壁的严格限制.通过Green-Kubo关系式计算得出了孔隙内氮气的导热系数,并与文献中的结果进行了比较,模拟结果接近于实验值,仅为同样条件下自由空间氮气的导热系数的1/3左右.     

Effect of charged groups on the adsorption and penetration of proteins onto and into carboxymethylated poly(HEMA) hydrogels

A range of carboxymethylated poly(hydroxyethyl methacrylate) (CM-PHEMA) hydrogels with varying degrees of carboxymethylation was synthesized for a systematic study of the effects of ionized groups ('charge') on the uptake by hydrogel matrices of the proteins, lysozyme and human serum albumin (HSA). Using a radiolabel-tracer technique, X-ray photoelectron spectroscopy, and laser scanning confocal microscopy, we attempted to differentiate between protein molecules that were irreversibly adsorbed onto the hydrogel surface and those that penetrated into the hydrogel matrix. The effective pore size of the CM-PHEMA hydrogels was modelled and compared with the known molecular dimensions of the two proteins. The effects of the presence of varying amounts of ionized groups in the hydrogel matrix differed for the two proteins. For lysozyme, increased uptake was observed at higher carboxymethylation; this is interpreted as resulting from a combination of electrostatic attraction and increasing ease of penetration of the protein into the more porous hydrogel matrix. For HSA, on the other hand, the uptake was primarily by surface adsorption, with little diffusive penetration into the matrix.     

烧结矿孔洞结构对烧结强度的影响

通过微型烧结研究了3种精矿粉造成烧结矿粘结相中孔洞结构形成差异的原因,测试并分析了孔洞的尺寸和分布对烧结矿强度的影响。结果表明:烧结矿强度与孔洞形态、数量和尺寸有关;液相扩展能力过大或太差的矿粉都会在烧结过程中引起烧结矿内孔洞尺寸和数量的增加,从而影响其强度。     

纳米隔热材料的孔隙结构特征与气体热传输特性

为研究纳米隔热材料孔隙结构内部的气体热传输特性, 采用溶胶-凝胶工艺结合超临界干燥技术, 制备了一系列具有不同孔隙结构特征的样品, 通过热导率、氮气吸-脱附和真密度测试, 全面、准确获取了其孔隙结构信息, 并专门、系统研究了孔隙结构特征与气体热传输特性之间的关系.研究结果表明: 与气相贡献热导率相对应, 材料具有双尺度孔隙结构特征, 并且当大孔隙尺度不及小孔隙的10倍时, 可进一步等效为单尺度孔隙.考虑气固耦合传热的本征气相贡献热导率随孔隙尺度的增大而升高, 与气相热导率变化类似且成一定的比例关系, 孔隙尺度小于200 nm和大于500 nm时的比例系数分别为2.0和1.5, 200~500 nm时则为2.0~1.5.当大、小孔隙尺度的比值不超过10时, 或者这一比值为100~1000且大孔隙含量低于10%时, 气相贡献热导率随环境气压的降低依次呈现快速下降、缓慢下降和无变化三个阶段; 当这一比值超过3000时, 即使大孔隙含量很低(不超过10%), 气相贡献热导率也会依次呈现快速下降、缓慢下降、快速下降和无变化四个阶段.      

Immediate and Time-Dependent Compression of Tire Derived Aggregate

This paper examines immediate and time-dependent compression of tire derived aggregate (TDA) and TDA-soil composites. To accommodate large particle sizes, modified experimental devices were developed and used to test tire chips and tire shreds. Immediate compression of TDA, which results almost entirely from the reduction of pore volume, increases with TDA content and tire particle size. The secant constrained modulus (Msec) of TDA defined over the stress range of 0–50?kPa varied from a low of 255?kPa (100% tire shreds) to a high of 1,320?kPa (50% tire chips). A characteristic relationship between strain and time exists for TDA and TDA composites under one-dimensional confined compression. Time-dependent deformation is well described by the modified secondary compression index (Cαε), which ranged from 0.0010 (50% tire chips) to 0.0074 (100% tire chips). Time-dependent deformation was inversely proportional to sand content, with the most significant changes resulting from the addition of 15% sand. Both applied stress and tire particle size appear to have a negligible effect on time-dependent compression of TDA. Based on the findings of this study it is recommended that practitioners assess time-dependent settlement when designing a TDA structure and if necessary incorporate design features to accommodate these settlements.     

Fabrication of a graded pore-sized porous FeAl intermetallic membrane

Micro-porous FeAl membranes were prepared directly onto a macro-porous FeAl support through brushing and reactive synthesis using Fe and Al elemental powders with different particle sizes. X-ray diffraction, scanning electron microscope and pore structure testing were used to study the phase composition, interfacial microstructure and pore structure of the resulting graded pore-sized FeAl membrane. The effects of membrane thickness on permeability and maximum pore size were also investigated. Results showed that a metallurgically strong joint is formed between the membrane and support and that no cracks and defects may be found on the interface due to the elemental reactions, penetrating of coated powders into the pores of the support and the match of the thermal expansion coefficients between membrane and support. Membrane permeability decreased from 84.2 to 38.5?m^3?m^?2?kPa^?1?h^?1 and the maximum pore size of about 2.5 μm showed a slight change as the membrane thickness increased from 135.5 to 299.1?μm.     

Further genetic analysis of the C-terminal external loop region in Escherichia coli maltoporin

LamB specifically facilitates the diffusion of maltose and maltodextrins through the bacterial outer membrane, and acts as a general (i.e. non-specific) porin for small hydrophilic molecules (< 600 daltons). We reported previously that deletion of the last predicted external domain near the C-terminus of the Eschirichia coli LamB protein (residues 376 to 405), affected in vivo the binding and transport of maltodextrins (specific pore functions), and also increased bacterial sensitivity to large antibiotics. The residues covered by this deletion correspond almost exactly to the major cell surface loop of LamB on the structural model based on X-ray crystallography (loop L9, residues 375 to 405). The L9 loop comprises a large central portion, which varies in size and sequence between the LamB proteins from different species. This variable region is flanked by two highly charged and conserved portions, which overlap with the adjacent beta strands. To identify subregions in L9 that influence the pore properties of LamB, we constructed and analysed nine mutants in loop L9 and its flanking sequences. Deletion of the 23-amino-acids central variable portion of the loop (residues 379 to 401), and deletion of the downstream conserved region (residues 402 to 409), only moderately affected specific maltoporin function. In contrast, deletion of the conserved region (residues 372 to 378) upstream of the variable portion strongly decreased specific maltoporin function and also increased sensitivity to large antibiotics, accounting for most, if not all, of the effects of the complete deletion of L9.     

Microstructure characteristics of dead stock coke from blast furnace

In order to reveal the relationship between the macroscopic properties and microstructure of dead stock coke, the differences between dead stock coke samples and feed coke samples were compared by industrial analysis, pore structure analysis, BET detection, XRD detection and SEM observation, etc. Dead stock coke samples and feed coke samples were both sampling from the stop experiment of a schreyerite BF in one factory in Xichang. Experimental results show that comparing with feed coke samples, the dead stock coke has significant differences in microcrystalline structure, stomatal structure, mineral distribution. The content of ash in dead stock coke increases, the number of super- atmospheric pores (pore size greater than 1000??m2) increases, the number of micropores (pore size of 0-50nm) and mesopores (pore size of 50-300nm) increase, and the crystallite size increases by about 4 times. In addition, the outer pores of the dead stock coke also adsorb a large amount of slag iron minerals, and the minerals are mainly magnesite, perovskite and iron carbon compounds. Then after the coke drops to the dead column area and stays for a long time, its porosity increases and the degree of graphitization increases.     

Preparation of High-Surface Area Nano-CeO2 by Template-Assisted Precipitation Method

The high-surface area nano-CeO2 was prepared by Ce（NO3）3 by precipitation method, with surfactant cetyhrimethyl ammonium bromide （CTAB） as templating agent. The effects of the precipitating agents, reaction temperature, ageing time, and calcination temperature on the surface area, as well as the pore structure and the mean crystallite size of nano-CeO2 were studied. It was found that the reaction of Ce（NO3）3 with NaOH in the presence of CTAB at 90℃ for 12 h yieldsed a cerium oxide/surfaetant mixture, which after calcination at 400℃ resulted in high-surface area nano-CeO2. The mean crystallite size of CeO2 was approximately 6 nm, surface area was in excess of 200 m^2· g ^- 1, pore size was approximately 9 nm, and the pore distribution was concentrative. Moreover, the surface area can still reach 147 m^2·g^- 1 after calcination at 700 ℃, which showed the good thermal stability of the CeO2. The number of oxygen vacancies in the structure of CeO2 corresponded with the surface area of CeO2, and the high surface area was propitious to the formalion of oxygen vacancies.     

A new step to the mechanism of the enhancement effect of gold nanoparticles on glucose oxidase

Quantum size effect was strongly supported by the experiment on correlation between size of gold nanoparticles (below 10 nm) and activity of glucose oxidase attached to them. The attractive enhancement effect of gold nanoparticles on the activity of glucose oxidase was then satisfactorily explained. In this experiment, 2 nm and 6 nm (average diameter) particles were obtained on monolayer matrix. The 2 nm particles proved to be much more able to increase the activity of glucose oxidase.     

Solvent debinding behavior of powder injection molded components prepared from powders with different particle sizes

It is generally accepted that the solvent debinding rate of powder injection molded (PIM) parts can be improved when coarse powder is used due to the larger pore size present in the compact. However, little hard experimental evidence on this has been reported. In this study, the as-received gas-atomized stainless steel powder was classified into four different particle sizes. Little difference in the debinding rate was found among these four groups. Similar results were also obtained using classified fine carbonyl iron powder and coarse water atomized iron powders. The diameter of the pore channel that was developed in the compact, while increasing as the particle size increased for both iron and stainless steel powders, did not affect the debinding rate. A comparison between the sizes of the pores and diffusing molecules suggests that the pores are significantly large for the small diffusing molecules. The calculation of the diffusion path or torturosity also indicates that the particle size does not affect the diffusion length and thus not the debinding rate.     

Involvement of lymphocyte function-associated antigen-1 and intercellular adhesion molecule-1 in osteoclastogenesis: a possible role in direct interaction between osteoclast precursors

In our search for molecules involved in the process of osteoclast differentiation, we examined the surface phenotypes of the preosteoclast-like cells and osteoclast-like multinucleated cells (MNCs) formed in bone marrow cultures, using monoclonal antibodies recognizing different antigen molecules expressed on hematopoietic cells. Among these cell surface antigens, lymphocyte function-associated antigen-1 (LFA-1) and intercellular adhesion molecule-1 (ICAM-1) were highly expressed on mononuclear cells in the cultures for forming preosteoclast-like mononuclear cells. The double detection of these two antigen molecules with osteoclast-specific antigen and with calcitonin receptor, using a fluorescence-activated cell sorter or autoradiography technique, revealed that LFA-1 and ICAM-1 were expressed on the preosteoclasts. The expression of ICAM-1 was detected on both preosteoclasts and osteoclast-like MNCs, whereas the expression of LFA-1 was restricted to preosteoclasts. We designed a peptide with the sequence of the binding site of ICAM-1 against the ligand LFA-1. In the whole bone marrow culture system for forming osteoclast-like MNCs, a significant inhibition of MNC formation was observed by the addition of this peptide. These results strongly suggest the involvement of an LFA-1/ICAM-1-interaction in osteoclastogenesis.     

Radial Pore Diffusion with Nonuniform Intraparticle Porosities

Effects of radially dependent intraparticle pore sizes on solute fate and transport are examined for batch systems with spherical particles using a recently developed numerical model. The model can accommodate multiple particles distributed in size, mass transfer resistance at particle boundaries, intraparticle reversible sorption kinetics, and first-order decays. Two applications are examined. In the first application, random or deterministic intraparticle porosities across a spherical particle are considered. In the second application, multiple particles distributed in sizes with particle size-dependent intraparticle porosities are studied. Results from these applications indicate that concentration profiles are largely determined by interplays between B, η, and ε that incorporate the effects of intraparticle pore structures. Steady-state concentration values in both applications are determined by the volume-averaged intraparticle porosities. These results could be useful for understanding solute tailing behavior in natural porous media and the design of synthetic sorbents for treatment of contaminated waters.