Determination of the specific surface by measurement of permeability

The determination of the specific surface of porous solids and packed powders from measurements of gas and liquid permeability is described. The theoretical background is outlined, and suitable experimental techniques are discussed, involving both constant and variable gas pressures.

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Résumé On décrit la détermination de la surface spécifique des poudres comprimées d’après des mesures de perméabilité des gaz et des liquides. On examine l’équation de Kozeny-Carman et ses applications. On décrit les techniques expérimentales appropriées, comprenant les méthodes à pression constante (Lea et Nurse, Rigden) et les méthodes à pression variable (Blaine). On souligne l’importance de ces mesures pour les essais de matériaux et l’on cite les normes nationales correspondantes.

     

Cellular uptake, cytotoxicity, and metabolic profiling of human cancer cells treated with ruthenium(II) polypyridyl complexes [Ru(bpy)2(N--N)]Cl2 with N--N=bpy, phen, dpq, dppz, and dppn

A series of five ruthenium(II) polypyridyl complexes [Ru(bpy)2(N--N)]Cl2 was tested against human HT-29 and MCF-7 cancer cell lines. Cellular uptake efficiency and cytotoxicity were found to increase with the size of the aromatic surface area of the N--N ligand. The most active compound carrying the dppn ligand exhibits a low micromolar IC(50) value against both cell lines comparable to that of cisplatin under similar conditions. Continuous measurement of oxygen consumption, extracellular acidification rate, and impedance of the cell layer with a chip-based sensor system upon exposure to the complexes showed only small changes for the first two parameters throughout the series. A significant and irreversible decrease in impedance was, however, found for the dppn compound. This suggests that its biological activity is related to modifications in cell morphology or cell-cell and cell-matrix contacts.     

Lipoprotein release by bacteria: potential factor in bacterial pathogenesis

Lipoprotein (LP) is a major component of the outer membrane of bacteria in the family Enterobacteriaceae. LP induces proinflammatory cytokine production in macrophages and lethal shock in LPS-responsive and -nonresponsive mice. In this study, the release of LP from growing bacteria was investigated by immuno-dot blot analysis. An immuno-dot blot assay that could detect LP at levels as low as 100 ng/ml was developed. By using this assay, significant levels of LP were detected in culture supernatants of growing Escherichia coli cells. During mid-logarithmic growth, approximately 1 to 1.5 microgram of LP per ml was detected in culture supernatants from E. coli. In contrast, these culture supernatants contained 5 to 6 microgram/ml of lipopolysaccharide (LPS). LP release was not unique to E. coli. Salmonella typhimurium, Yersinia enterocolitica, and two pathogenic E. coli strains also released LP during in vitro growth. Treatment of bacteria with the antibiotic ceftazidime significantly enhanced LP release. Culture supernatants from 5-h cultures of E. coli were shown to induce in vitro production of interleukin-6 (IL-6) by macrophages obtained from LPS-nonresponsive C3H/HeJ mice. In contrast, culture supernatants from an E. coli LP-deletion mutant were significantly less efficient at inducing IL-6 production in C3H/HeJ macrophages. These results suggest, for the first time, that LP is released from growing bacteria and that this released LP may play an important role in the induction of cytokine production and pathologic changes associated with gram-negative bacterial infections.     

CSE vs. augmented epidural anesthesia for cesarean section. Spinal and epidural anesthesia with bupivacaine 0.5% "isobar" require augmentation

Incomplete anaesthesia is a major clinical problem both in single spinal and in single epidural anaesthesia. The clinical efficacy of epidural anaesthesia with augmentation (aEA) and combined epidural and spinal anesthesia (CSE) for cesarean section was investigated in a prospective randomized study on 45 patients. METHODS: Anaesthesia extending up to Th5 was aimed for. Depending on the patient's height, epidural anaesthesia was administered with a dose of 18-22 ml 0.5% bupivacaine and spinal anaesthesia with a dose of 11-15 mg 0.5% bupivacaine. Augmentation was carried out in all cases in epidural anaesthesia, initially with 7.5 ml 1% Lidocaine with epinephrine 1:400,000, raised by 1.5 ml per missing segment. The epidural reinjection in CSE was carried out as necessary with 9.5-15 ml 1% lidocaine with epinephrine, depending on the height and difference from the segment Th5. RESULTS: The extension of anaesthesia achieved in epidural anaesthesia after an initial dose of 101.8 mg bupivacaine and augmenting dose of 99 mg lidocaine reached the segment Th5. The primary spinal anaesthesia dose up to 15 mg corresponding to height led to a segmental extension to a maximum of Th3 under CSE. Augmentation was necessary in 13 patients; in 5 cases because of inadequate extent of anaesthesia and 8 cases because of pain resulting from premature reversion. The augmenting dose required was 13.9 ml. Readiness for operation was attained after 19.8 min (aEA) and after 10.5 min (CSE). No patient required analgesics before delivery. The additional analgesic requirement during operation was 63.6% (aEA) and 39.1% (CSE). Taking into account pain in the area of surgery, the requirement of analgesics was 50% (aEA) vs. 17.4% (CSE). Antiemetics were required in 18.2 (aEA) and in 65.2% (CSE). The systolic blood pressure fell by 17.7% (aEA) and in 30.3% (CSE). The minimum systolic pressure was observed after 13.4 min in aEA, and after 9.5 min in CSE. The APGAR score and the umbilical pH did not show any differences. General anaesthesia was not required in any case.     

A novel approach to realize the local precise variotherm process in micro injection molding

Variotherm is special mould temperature controlling concept which realizes the rapid heating/cooling of mould during material processing in order to extend the freezing time of materials. A novel variotherm concept based on silicon wafer combined with micro electric resistance heating structures is purposed and prototyped in this study. The manufacture process of this variotherm unit was introduced and its heating/cooling performance was tested and analyzed by thermal graphic method, which indicate that the new variotherm concept has excellent thermal control efficiency and precise temperature distributions.     

Synthesis of Polystyrene-Bound Organotin Derivatives as Intermediates for the Production of Hybrid Materials

Polystyrenes bearing tricyclohexylstannyl moieties with different stereoregularities, molecular weights, and chemical composition have been prepared and characterized through two synthetic routes. The suitability of the products obtained to be used as intermediate derivatives in the synthesis of the corresponding organotin trichlorides, precursors to organic–inorganic hybrid materials, has been investigated.     

Hybrid Organic–Inorganic Copolymers from Oxohydroxoorganotin Dimethacrylate and Methyl Methacrylate

Organic–inorganic polymeric derivatives constituted by methyl methacrylate co-units and an oxohydroxobutyltin macrocation difunctionalized with methacrylate counterions have been prepared by radical polymerization in solution. The reaction affords soluble products, indicative of a substantial absence of cross-linking originated by the difunctional macrocationic comonomer, when the molar excess of methyl methacrylate is high. The organic–inorganic hybrid products obtained have been characterized by various techniques, thus allowing us to propose a mechanism for their formation which implies a role as chain termination agent for the macrocationic monomer.