A novel containment system for laboratory-scale solid particulate fermentations

Summary A novel containment system using a microporous film material is described for laboratory-scale solid particulate fermentations. The microporous film allows efficient air and moisture vapour transmission without cross-contamination. The non-autoclaved substrates support vigorous fungal growth and sporulation within the containment bags.     

Improved selectivity and stability of glucose biosensor based on in situ electropolymerized polyaniline-polyacrylonitrile composite film

A new type of in situ electropolymerization method was used for electrochemical biosensor design. The biologic film was prepared by in situ electropolymerization of aniline into microporous polyacrylonitrile-coated platinum electrode in the presence of glucose oxidase. The novel glucose biosensor exhibited good selectivity, sensitivity and stability, which showed no apparent loss of activity after 100 consecutive measurements and intermittent usage for 100 days with storage in a phosphate buffer at 4 degrees C. Blood glucose determinations agreed well with standard hospital laboratory analysis. The construction and operational parameters of the biosensor were also optimized.     

Mass transfer characteristics of hydrophobic tubing membrane sensors

Summary The total resistance to transfer through a hydrophobic membrane used in the tubing method is due to an external liquid film and to the membrane itself. The global mass transfer coefficient is higher for alcohols than for other tested volatiles. PTFE microporous membranes are recommended.     

A low-cost alternative membrane system that promotes growth in nodal cultures of Brazilian ginseng [Pfaffia glomerata (Spreng.) Pedersen]

In vitro propagated plants under conditions of low gas exchange generally show morphological and physiological anomalies that lead to high mortality rates during ex vitro acclimatization. The use of gas-permeable membranes increases natural ventilation in culture vessels, photosynthesis and growth rates. However, commercial membranes are expensive, which limits their application. In this study, low-cost, simple to manufacture, alternative membranes were developed to promote gas exchange in jars used for in vitro plant tissue culture. The membranes were developed using polytetrafluoroethylene film and two or three layers of microporous tape (Missner & Missner^?), and were designed to increase the growth of nodal cultures of Pfaffia glomerata (Brazilian ginseng). Conditions that provided higher gas exchange led to an increase in plant growth and content of photosynthetic pigments compared to a closed system without a gas-permeable membrane. The alternative membranes showed similar results for water vapor loss rate and photosynthetic pigments when compared to a commercial membrane. The alternative membranes were also an efficient barrier against contamination and remained intact after being autoclaved multiple times. Among the membranes tested, the traits of the P. glomerata in vitro-derived plants were similar when propagated using the alternative membrane with three layers of microporous tape or the commercial membrane. However, the alternative membrane has a unit cost that is ten times lower than the commercial membrane.     

The matrix form of collagen and basal microporosity influence basal lamina deposition and laminin synthesis/secretion by stratified human keratinocytes in vitro

Summary The ability of the collagen matrix form to support the formation of a basal lamina by cultured normal human epidermal keratinocytes (NHEK) was determined using transmission electron microscopy. The collagen matrix forms tested in this study were a) a dry type I collagen film and b) a type I collagen gel. NHEK were grown for 14 days on the following five different substrates: plain plastic culture dishes without the addition of collagen (PP); plain plastic culture dishes overlaid with a dry, aldehyde-crosslinked type I collagen film (DCF-P); plain plastic culture dishes overlaid with an aldehyde-crosslinked type I collagen gel (GEL-P); Millipore Millicell CM microporous membranes overlaid with a dry, aldehyde-crosslinked type I collagen film (DCF-CM); and Millipore Millicell CM microporous membranes overlaid with an aldehyde-crosslinked type I collagen gel (GEL-CM). NHEK maintained for 2 wk on PP and DCF-P were unable to secrete a basal lamina. NHEK grown for 2 wk on the GEL-P and GEL-CM substrates, however, secreted a contiguous basal lamina at the GEL-NHEK interface. To determine if the appearance of this basal lamina correlated with laminin synthesis, laminin was immunoprecipitated from cellular extracts, as well as media from the apical and basal chambers. NHEK grown on the GEL-P substrate synthesized more laminin than did NHEK grown on the other four alternative substrates. In addition, NHEK grown on GEL-CM were able to direct more laminin to the basal compartment than NHEK grown on DCF-CM substrates. Taken together, the data indicate that the matrix form of collagen can influence basal lamina deposition, laminin synthesis, and laminin trafficking in NHEK.     

Application of a luminescence-based pH optrode to monitoring of fermentation by Klebsiella pneumoniae

The application of an optical sensor based on immobilization of the ruthenium complex [Ru(bpy)2(dhphen)]2+ (bpy = 2,2'-bipyridine, dhphen = 4,7-dihydroxy-1,10-phenanthroline) in Nafion to pH monitoring of fermentation by Klebsiella pneumoniae is described. Interference from the culture medium can be eliminated by addition of a black microporous filter membrane (pore size: 0.45 microm) on top of the sensing film. The response of this pH optrode was found to show good correlation with the conventional pH electrode.     

Fabrication of drug-eluting covered stents with micropores and differential coating of heparin and FK506

To reduce in-stent restenosis rates, we developed a novel drug-eluting covered stent with a microporous elastometric covered film, in which its luminal surface was flat and immobilized with heparin for anticoagulation and its outer surface immobilized with FK506 to prevent neointimal hyperplasia. One month after implantation into the bilateral common carotid arteries, all stented arteries were patent and the luminal surfaces were fully covered with a confluent of endothelial cells irrespective of the drug immobilization. In the control group, which consisted of covered stents without drug immobilization, intensive inflammatory cells adjacent to the stents and neointimal hyperplasia, indicating vascular injury, were observed. In contrast, in the developed drug-eluting stents, only a few inflammatory cells around the stent strut and covered film were observed, and there was no significant neointimal thickening.     

Laccase electrode for the continuous-flow determination of phenolic compounds

Summary Laccase (p-diphenol, O₂ oxido-reductase, E.C. 1.10.3.2) from Botrytis cinerea was immobilized in a gelatin support on an O₂ sensing electrode. The enzyme was copolymerized with the inert protein using glutaraldehyde (1.25 % w/w) on the hydrophobic selective gas membrane of a pO₂ sensor and this was covered with a Nuclepore polycarbonate microporous film (0.03 m). The enzyme electrode was used in a continuous-flow system to measure the concentration of a wide range of phenolic substrates. The measuring time of each sample was about 1.5 min including response and rinsing times. The electrode response was set for hydroquinone up to 0.8 mM with high reproducibility and less than 5 % error.The electrode response for hydroquinone concentration of 0.25 mM was stable with repeated use for at least 800 assays without significant loss of activity.     

Evaluation of encapsulating and microporous nondegradable hydrogel scaffold designs on islet engraftment in rodent models of diabetes

Islet transplantation is a promising therapeutic option for type 1 diabetes mellitus, yet the current delivery into the hepatic portal vasculature is limited by poor engraftment. Biomaterials have been used as a means to promote engraftment and function at extrahepatic sites, with strategies being categorized as encapsulation or microporous scaffolds that can either isolate or integrate islets with the host tissue, respectively. Although these approaches are typically studied separately using distinct material platforms, herein, we developed nondegradable polyethylene glycol (PEG)‐based hydrogels for islet encapsulation or as microporous scaffolds for islet seeding to compare the initial engraftment and function of islets in syngeneic diabetic mice. Normoglycemia was restored with transplantation of islets within either encapsulating or microporous hydrogels containing 700 islet equivalents (IEQ), with transplantation on microporous hydrogels producing lower blood glucose levels at earlier times. A glucose challenge test at 1 month after transplant indicated that encapsulated islets had a delay in glucose‐stimulated insulin secretion, whereas microporous hydrogels restored normoglycemia in times consistent with native pancreata. Encapsulated islets remained isolated from the host tissue, whereas the microporous scaffolds allowed for revascularization of the islets after transplant. Finally, we compared the inflammatory response after transplantation for the two systems and noted that microporous hydrogels had a substantially increased presence of neutrophils. Collectively, these findings suggest that both encapsulation and microporous PEG scaffold designs allow for stable engraftment of syngeneic islets and the ability to restore normoglycemia, yet the architecture influences islet function and responsiveness after transplantation.     

The galactose biosensor based on microporous polyacrylonitrile

A galactose biosensor is obtained by immobilizing galactose oxidase (GAO) in a microporous polyacrylonitrile (PAN) thin film. The effects of pH, potential and temperature on response current are studied. The optimum pH and apparent activation energy of enzyme-catalyzed reaction are 7.1 and 31.1 kJ mol^-1, respectively. The response current of the biosensor increases linearly with the increasing galactose concentration from 0.02 to 1.60 mmol dm^-3. The Michaelis-Menten constant value (K _m ^app) is 12.15 mmol dm^-3. The biosensor shows good operational stability and reproducibility. The galactose biosensor is characterized with cyclic voltammogram, FTIR and UV-Vis.     

蒙药材多叶棘豆中五种微量元素的形态分析

本文采用水煎法对蒙药材多叶棘豆中微量元素进行提取,并分别用微孔滤膜分离技术、大孔吸附树脂柱分离法、萃取法等分离方法对水煎液中元素各形态进行分离。利用FAAS法测定了原药材以及水煎液各形态中Cu、Zn、Mn、Fe和Ca五种微量元素含量并进行了形态分析。分析结果表明,水煎液中五种元素的总提取率在41.7%～87.0%,残留率在9.1%～26.4%,可溶态百分率在16.6%～80.0%,可溶态中五种元素的有机态与无机态的比例为36.9%～250%;该测定方法对各元素的加标回收率在90.3%～113.7%。多叶棘豆水煎液可溶态中Zn、Mn、Fe、Ca元素是以亲水性有机结合形态为主,Cu元素以无机离子型为主,多种形态共存的复杂体系。     

Molecular recognition of carbohydrates by a resorcinarene. Selective transport of alditols through a supported liquid membrane

A supported liquid membrane (SLM) containing a resorcinarene carrier has been used for the selective transport of erythritol, threitol, ribitol and xylitol from concentrated (1.0-0.01 M) aqueous solutions. The membrane is made of a microporous polytetrafluoroethylene film impregnated with a 0.01 M solution of the carrier in CCl4. The permeabilities of the SLM for all alditols were calculated. On the basis of the flux dependence on the initial concentrations of carrier and alditol, the rate-determining step in the transport mechanism is shown to be the migration of the 1:1 carrier-carbohydrate complex in the immobilized organic phase. The flux of sugar is related to the initial concentration of alditol in the feed phase by a saturation law, which allowed the determination of the apparent diffusion coefficients and the stability constants of the resorcinarene complexes of alditols formed in the liquid membrane.     

The galactose biosensor based on microporous polyacrylonitrile

A galactose biosensor is obtained by immobilizing galactose oxidase (GAO) in a microporous polyacrylonitrile (PAN) thin film. The effects of pH, potential and temperature on response current are studied. The optimum pH and apparent activation energy of enzyme-catalyzed reaction are 7.1 and 31.1?kJ?mol^?1, respectively. The response current of the biosensor increases linearly with the increasing galactose concentration from 0.02 to 1.60?mmol?dm^?3. The Michaelis–Menten constant value (K_m^app) is 12.15?mmol?dm^?3. The biosensor shows good operational stability and reproducibility. The galactose biosensor is characterized with cyclic voltammogram, FTIR and UV-Vis.     

Modification of macroporous titanium tracheal implants with biodegradable structures: tracking in vivo integration for determination of optimal in situ epithelialization conditions

Previously, we showed that macroporous titanium implants, colonized in vivo together with an epithelial graft, are viable options for tracheal replacement in sheep. To decrease the number of operating steps, biomaterial-based replacements for epithelial graft and intramuscular implantation were developed in the present study. Hybrid microporous PLLA/titanium tracheal implants were designed to decrease initial stenosis and provide a surface for epithelialization. They have been implanted in New Zealand white rabbits as tracheal substitutes and compared to intramuscular implantation samples. Moreover, a basement membrane like coating of the implant surface was also designed by Layer-by-Layer (LbL) method with collagen and alginate. The results showed that the commencement of stenosis can be prevented by the microporous PLLA. For determination of the optimum time point of epithelialization after implantation, HPLC analysis of blood samples, C-reactive protein (CRP), and Chromogranin A (CGA) analyses and histology were carried out. Following 3 weeks the implant would be ready for epithelialization with respect to the amount of tissue integration. Calcein-AM labeled epithelial cell seeding showed that after 3 weeks implant surfaces were suitable for their attachment. CRP readings were steady after an initial rise in the first week. Cross-linked collagen/alginate structures show nanofibrillarity and they form uniform films over the implant surfaces without damaging the microporosity of the PLLA body. Human respiratory epithelial cells proliferated and migrated on these surfaces which provided a better alternative to PLLA film surface. In conclusion, collagen/alginate LbL coated hybrid PLLA/titanium implants are viable options for tracheal replacement, together with in situ epithelialization.     

Evaluation of filters for recovery of Campylobacter jejuni from water.

Campylobacter jejuni has been incriminated in several large waterborne outbreaks, but it has rarely been isolated from water itself. Better methodology is needed for the isolation of C. jejuni from water. We evaluated three types of 0.45-micron microporous filters and three different pore sizes of positively charged depth filters for their ability to recover C. jejuni from seeded, sterile tap and surface water. The microporous filters tested were Millipore HA, Gelman GN6, and Zetapor. Three pore sizes of Zeta Plus depth filters (05S, 30S, and 50S) were evaluated by using an adsorption-elution technique. The overall percent recovery in both tap and surface water by microporous filters was: Zetapor, 66%; Millipore HA, 33%; and Gelman GN6, 33%. Adsorption-elution with Zeta Plus 50S allowed 89% recovery of C. jejuni. These data suggest that both the positively charged Zetapor microporous filter and the Zeta Plus 50S depth filter are effective filters for the recovery of C. jejuni from water.     

Evaluation of filters for recovery of Campylobacter jejuni from water

Campylobacter jejuni has been incriminated in several large waterborne outbreaks, but it has rarely been isolated from water itself. Better methodology is needed for the isolation of C. jejuni from water. We evaluated three types of 0.45-micron microporous filters and three different pore sizes of positively charged depth filters for their ability to recover C. jejuni from seeded, sterile tap and surface water. The microporous filters tested were Millipore HA, Gelman GN6, and Zetapor. Three pore sizes of Zeta Plus depth filters (05S, 30S, and 50S) were evaluated by using an adsorption-elution technique. The overall percent recovery in both tap and surface water by microporous filters was: Zetapor, 66%; Millipore HA, 33%; and Gelman GN6, 33%. Adsorption-elution with Zeta Plus 50S allowed 89% recovery of C. jejuni. These data suggest that both the positively charged Zetapor microporous filter and the Zeta Plus 50S depth filter are effective filters for the recovery of C. jejuni from water.     

Fabrication of Ordered Macro‐Microporous Single‐Crystalline MOF and Its Derivative Carbon Material for Supercapacitor

Because of their good performance in diffusion‐limited processes, ordered macro‐microporous single‐crystalline metal‐organic frameworks (MOFs) have potential for use in various fields. However, there are still very few reports of the synthesis of such MOFs. A general synthesis methodology for ordered macro‐microporous single‐crystalline MOFs is highly desired. Here, a novel strategy is reported for synthesizing single‐crystalline ordered macro‐microporous MOFs by monodentate‐ligand‐induced in situ crystallization within a 3D ordered hard template in a double‐solvent system. A space‐confined growth model is proposed to clarify the shaping effect of the template; the role of the monodentate ligand is also analyzed. Moreover, a carbon material derived from the macro‐microporous MOF inherits the ordered interconnected macroporous structure. The improved diffusion and lower resistance, as well as the structural robustness, endow the derivative carbon material with superior rate performance and excellent cycling stability when prepared as electrodes for a supercapacitor. It is anticipated that the method will provide new paths to the synthesis of such macro‐microporous materials for applications in energy‐related fields and beyond.     

Lacustrine microporous micrites of the Madrid Basin (Late Miocene,Spain) as analogues for shallow-marine carbonates of the Mishrif reservoir Formation (Cenomanian to Early Turonian,Middle East)

Shallow-marine microporous limestones account for many carbonate reservoirs. Their formation, however, remains poorly understood. Due to the lack of recent appropriate marine analogues, this study uses a lacustrine counterpart to examine the diagenetic processes controlling the development of intercrystalline microporosity. Late Miocene lacustrine microporous micrites of the Madrid Basin (Spain) have a similar matrix microfabric as Cenomanian to Early Turonian shallow-marine carbonates of the Mishrif reservoir Formation (Middle East). The primary mineralogy of the precursor mud partly explains this resemblance: low-Mg calcites were the main carbonate precipitates in the Cretaceous seawater and in Late Miocene freshwater lakes of the Madrid Basin. Based on hardness and petrophysical properties, two main facies were identified in the lacustrine limestones: a tight facies and a microporous facies. The tight facies evidences strong compaction, whereas the microporous facies does not. The petrotexture, the sedimentological content, and the mineralogical and chemical compositions are identical in both facies. The only difference lies in the presence of calcite overgrowths: they are pervasive in microporous limestones, but almost absent in tight carbonates. Early diagenetic transformations of the sediment inside a fluctuating meteoric phreatic lens are the best explanation for calcite overgrowths precipitation. Inside the lens, the dissolution of the smallest crystals in favor of overgrowths on the largest ones rigidifies the sediment and prevents compaction, while partly preserving the primary microporous network. Two factors appear essential in the genesis of microporous micrites: a precursor mud mostly composed of low-Mg calcite crystals and an early diagenesis rigidifying the microcrystalline framework prior to burial.     

半干旱黄土高原地区春小麦地膜覆盖研究概述

在黄土高原半干旱地区春小麦上进行的地膜覆盖试验表明,地膜覆盖通过改善耕层土壤生态环境条件,即通过改善水,热状况,活化土壤养分,对提高水分和养分利用效率,实现粮食增产具有重要作用,但近年来在生产实践和科学实验中发现,不合理的长期全生育期地膜覆盖,因在作物生长前期和中期覆膜作物较不覆膜作物生长好,覆膜作物在生长期水分蒸腾损失严重,土壤水分的蒸散（蒸发＋蒸腾）损失远比不覆膜土壤严重,在作物生长后期降水少或没有补充灌溉时,会产生严重的水分肋迫现象,显著抑制小穗分化和灌浆,最终导致收获得指数和产量下降,同时,地膜覆盖的增产作用在一定程度上是以耗竭土壤肥力,特别是在有机物质为代 的,因此,不正确的地膜覆盖（如全生育期的地膜覆盖）,不仅有时起不到显著的增产作用,而且易造成土壤养分,特别是土壤中硝态氮的累积和损失,肥料利用效率降低,土壤生态条件恶化,下降,难以持续高产,因此在确定地膜覆盖范式时,必须要考虑底墒,作物生育期降水,地膜覆盖的阶段性和氮肥的施用等。     

A filtration method for measuring cellular uptake of [14C]methylamine and other highly permeant solutes

A filtration technique has been developed for study of the uptake of [14C]methylamine by Azotobacter vinelandii. This dual filter arrangement requires a precision microporous polycarbonate film which overlays a paper filter. Cellular uptake of radioactivity is terminated by vacuum filtration of the reaction mixture onto the polycarbonate filter without dilution or washing. Filtration was complete in 0.7 s with retention of less than 0.2% of the extracellular radioactivity. The dual filter method gave 20-fold higher levels for intracellular methylamine than filtration followed by washing. Without washing, nitrocellulose filters retained 18 times more extracellular [3H]sorbitol and 80 times more extracellular [14C]methylamine than polycarbonate filters. Use of an underlying paper filter did not significantly improve the performance of nitrocellulose filters. However, addition of a paper filter reduced extracellular methylamine and sorbitol retention on polycarbonate filters by 77 and 86%, respectively. This method is generally applicable to measurement of the uptake of highly permeant molecules by cells and subcellular organelles.