Abtrennung und Rückgewinnung von gasförmigen Stoffen durch Adsorption

Separation and recovery of gaseous substances by adsorption. After making a number of fundamental remarks on adsorbents, equilibrium, and kinetics of adsorption from the gas phase, the authors of this article first present a variety of regeneration methods. There follows a brief account of the methods used in the design of fixed bed adsorbers. The reader is then led via considerations of safety in the construction and operation of adsorbers to a number of practical examples from the areas of solvent recovery and flue gas purification.     

Effect of Wet–Dry Cycles and Cation Exchange on Gas Permeability of Geosynthetic Clay Liners

A series of gas permeability tests were performed on a partially hydrated needle punched geosynthetic clay liner (GCL) after exposure to wet–dry cycles and ion exchange. To be able to evaluate the effect of wetting and drying cycles combined with the effect of cation exchange, three sets of GCL samples were prepared with different types of hydrating liquid. The first set of GCL samples was hydrated with de-ionized water, which formed a baseline test series. The second and third sets were hydrated with 0.0125 and 0.125?M calcium chloride (CaCl2) solutions, respectively. All three sets of GCL samples were subjected to multiple wetting and drying cycles before undergoing gas permeability tests. Gas permeability of the GCL, hydrated with 0.0125?M calcium chloride solution, was found to be approximately one order of magnitude higher than that of the GCL hydrated with de-ionized water, whereas gas breakthrough flow was observed for all but the first wetting cycle on GCLs hydrated with the stronger 0.125?M calcium chloride solution.     

Interest of gene amplification by PCR for the diagnosis of Mycoplasma pneumoniae infections in the child

The relationship between preoperative serum carcinoembryonic antigen (CEA), CA 19-9 and alpha-fetoprotein (AFP) levels and their clinicopathological features were evaluated in gastric cancer patients. The positive rates of CEA, CA 19-9 and AFP were 24.8, 27.6 and 12.7%, respectively. Gastric cancer with deeper tumor invasion was significantly more common among patients positive for these tumor markers. Patients with positive CEA or CA 19-9 values had a significantly high risk of lymph node metastases (p = 0.045 and p = 0.002, respectively). Synchronous liver metastases was more commonly found in patients with a positive CA 19-9 value. A significant difference (p < 0.001) in survival rate was found between patients with positive CA 19-9 values and those with negative values. CA 19-9 is useful for the prognosis of gastric cancer patients, whereas CEA, although unsuitable for prognosis, contributes to the prediction of cancer invasion.     

The undecidability of the unification and matching problem for canonical theories

Summary The problem whether there exists a unifying substitution for two terms is considered in the class of theories which can be embedded into canonical term rewriting systems. The problem is shown to be undecidable, even if we restrict the substitutions to matching ones. This implies that the class of admissible canonical theories is a proper subset of the class of canonical theories.     

Gene and other biological therapies for vascular diseases

Gene transfer and antisense therapy offer novel approaches to the study and treatment of vascular diseases. The localized nature of vascular diseases like restenosis has made the application of genetic material an attractive therapeutic option. Viral and nonviral vectors have been developed to facilitate the entry of foreign DNA or RNA into cells. Vector improvement and production, demonstration of vector safety and demonstration of therapeutic efficacy are among the main present challenges. Various strategies have already been shown to be successful in preventing restenosis in animal models and include: the transfer of the herpes simplex virus thymidine kinase associated with ganciclovir: transfection of the cell cycle regulatory genes encoding for the active form of retinoblastoma gene product (Rb) or the cyclin-dependent kinase inhibitor p21, and antisense therapy. Therapeutic angiogenesis using gene transfer is a new strategy for the treatment of severe limb ischemia. Transfection of DNA encoding for the vascular endothelial growth factor has resulted in increasing collateral flow in animal models of peripheral ischemia. This approach is currently being investigated in a clinical trial in patients with distal ischemia. Other potential targets for genetic treatment in cardiovascular diseases include thrombosis, extracellular matrix synthesis and lipid metabolism.     

In vivo infusion of anti-LFA-1 and anti-CD2 antibodies prevents graft failure after HLA partially incompatible bone marrow transplantation in children with high risk acute lymphoblastic leukaemia

Bone marrow transplantation (BMT) from matched sibling donors is the therapy of choice for children with high-risk acute lymphoblastic leukaemia in children. It is however not available to more than two-thirds of patients who lack a matched donor. Here, we review the outcome of 28 patients with high-risk ALL who were transplanted in France with alternative marrow sources such as HLA-phenoidentical unrelated volunteers and HLA-partially incompatible relatives. For these patients, we tested the possibility to prevent T-depleted marrow graft rejection by infusing in vivo two monoclonal antibodies directed against adhesion receptors i.e., LFA-1 and CD2. Two previous multicenter trials in children transplanted with partially incompatible bone marrow for inborn errors of metabolism showed their efficacy in this setting. Twenty eight patients were enrolled in this study and followed for a median of 4.4 years. Bone marrow engraftment occurred in 81% of the evaluable patients. Post-transplantation leukaemic relapse was the most frequent cause of death in this group of patients, and occurred in 39% of patients. The second most frequent complication was infectious disease, while an EBV-induced B-lymphocyte proliferative disorder occurred in four patients. In conclusion, T-cell-depletion combined with infusion of anti-LFA-1 and anti-CD2 antibodies is efficient in preventing graft failure and GVHD in this group of children with high-risk leukaemia undergoing partially incompatible BMT. The overall DFS is not improved in contrast to what has been previously observed in patients with immunodeficiencies transplanted with a similar rejection prophylaxis. Other approaches are therefore needed aiming either at preserving donor T-cell mediated immunity or accelerating immune reconstitution.     

Inexpensive short-range microwave telemetry transponder

A microwave transponder is described which is suitable for short-range telemetry applications requiring an inexpensive transmitter. Two antiparallel beam-lead diodes at the terminals of a bow-tie antenna produce double-sideband suppressed-carrier modulation centred about the second harmonic of an externally supplied fundamental carrier. A simple theory predicting performance of the device is confirmed by experiment.     

Problems with the random number generator RANF implemented on the CDC cyber 205

We show that using RANF may lead to wrong results when lattice models are simulated by Monte Carlo methods. We present a shift-register sequence random number generator which generates two random numbers per cycle on a two pipe CDC Cyber 205.