Thermal behavior of ungrafted and grafted bagasse and wood pulps

The effect of grafting of methyl methacrylate (MMA) and acrylonitrile (AN) on the thermal behavior of the pulp of sugar cane loaded with CaCO₃ and the pulp of a broad-leaved tree has been studied by thermal methods. Different experimental conditions of grafting AN onto the eucalyptus pulp have been used, including both water and organic solvent systems as the medium of reaction. To optimize the grafting of MMA onto wood pulp, the effect of pulp swelling and the contact time of the monomer with the pulp have been examined. Ungrafted as well as grafted cellulose samples with different levels of grafting were characterized by differential scanning calorimetry (DSC) and the thermogravimetric analysis (TGA). The CaCO₃ filler makes the pulp of bagasse thermally more stable. The grafting of MMA onto the bagasse or the wood pulps improves their thermal stability. This is not the case for wood grafted with poly(AN). The thermal stability of the grafted and ungrafted samples varies after a few weight percent has been lost. The glass transition temperature (T_g) of the copolymers have been measured and they are in good agreement with the calculated data. © 1993 John Wiley & Sons, Inc.     

Atrial defibrillators or implantable atrioverters. Initial results

The atrial defibrillator is a new non-pharmacological treatment of atrial fibrillation (AF) for restoration of sinus rhythm. This device has two programmable modes: automatic or activated by the physician or patient. In the automatic mode, the device delivers a shock synchronous with the R wave to restore sinus rhythm when AF is detected. Two patients with paroxysmal AF resistant to pharmacological therapy were included in a study to assess the efficacy and safety of the atrial defibrillator in the mode activated by the physician. The device implanted in the pectoral region is connected to 3 electrodes, two for atrial defibrillation and sensing positioned in the coronary sinus and right atrium respectively and a sensing and pacing electrode in the right ventricle. The right ventricle is paced if a post-shock pause is detected. It is possible to interrogate the device with a programmer using its Holter function and so determine the number of episodes of AF sensed and treated. The number, intensity and energy of the shocks and the parameters of ventricular stimulation are programmable. In these two patients, the atrial defibrillator effectively reduced prolonged episodes of AF with a follow-up of 12 and 7 months. No pro-arrhythmic effects were observed. Further clinical evaluation is under way to assess this new mode of treatment, including the mode activated by the patient, safety and tolerance of the shocks. In our two patients, the treatment of prolonged episodes of AF was followed by reduction of many short or asymptomatic episodes.     

Glucagon-like peptide-1-(7-36)amide increases pulmonary surfactant secretion through a cyclic adenosine 3',5'-monophosphate-dependent protein kinase mechanism in rat type II pneumocytes

Glucagon-like peptide-1 (GLP-1) receptor messenger RNA has been identified in cells considered type II pneumocytes that are involved in the synthesis and secretion of the pulmonary surfactant. In an attempt to open new insights into the control of surfactant secretion, we studied the effects of glucagon-related peptides in this process. Accordingly, type II pneumocytes were isolated from Wistar rat lungs and cultured overnight with [methyl-14C]choline, and then the basal and stimulated secretions of [14C]phosphatidylcholine were measured. GLP-1(7-36)amide stimulated phosphatidylcholine secretion in a concentration-dependent manner in the 1-100 nM range; the concentration of the peptide that produced a half-maximal response was 10 nM. Exendin-4 induced similar effects. No changes were observed when GLP-1-(1-37), GLP-2, or exendin-(9-39) was added to the medium. However, the latter reversed the stimulatory effects of GLP-1-(7-36)amide and exendin-4. A study of the mechanism through which GLP-1-(7-36)amide exerts its stimulatory effect was carried out using different agents that are well known stimulants of phosphatidylcholine secretion. GLP-1-(7-36)amide did not produce any change in the stimulatory effect observed with terbutaline or 8-bromo-cAMP, suggesting the involvement of a cAMP-dependent protein kinase in the stimulatory effect of this peptide on phosphatidylcholine secretion. It was further supported by the use of inhibitors of protein kinases and by the stimulation of cAMP production in type II pneumocytes incubated with either GLP-1-(7-36)amide or exendin-4.     

On the geometric component of charge-pumping current in MOSFETs

A simple method of unambiguously determining the presence of any geometric component in a charge-pumping measurement by collecting this component at another node via a nearby junction is presented. With the method it has been possible to study the dependence of geometric components on device dimensions and various experimental conditions with unprecedented sensitivity. By effectively separating the two current contributions, this method can at the same time be used to reduce geometric components in the regular charge-pumping signal, thereby increasing the accuracy of the various implementations of the charge pumping (CP) technique     

Bestimmung niedriger Borgehalte in feuerfesten Stoffen und Stahlwerksschlacken

Anpassen des für die Stahlanalyse entwickelten photometrischen Curcuminverfahrens an die Belange der Oxidanalyse. Vergleich mit dem für die Untersuchung von Magnesitprodukten vorgeschlagenen Carminsäureverfahren sowie mit drei weiteren photometrischen Verfahren.     

The geothermal zone of lake Assal (F.T.A.I.), geochemical and experimental studies

A geothermal model of Lake Assal region (F.T.A.I.) was derived from in situ observations and chemical and isotopic studies of hot and cold springs.According to this model, the lake water supply is provided mainly by sea water infiltrating from Ghoubbet el Kharab and, for a small part, by highly mineralized hot spring water of meteoric origin.Temperatures at depth were determined by means of various methods (among them a new one). These temperatures were found to range from 150 to 170°C.A geochemical experimental study of this model is under way.     

DIVA: Recognition of typical situations for turbine generator diagnosis

DIVA is an expert system for turbine generator diagnosis. Its aim is to help a plant operator interpret vibration evolution to diagnose developing faults. Interpretation of vibration evolution is primarily a recognition process which is achieved by a particular model of heuristic classification. DIVA tries to recognize the observed situation among a hierarchy of typical situations.The purpose of this paper is to present the model we used for heuristic classification, based on prototypes. Prototypes represent typical problem situations and may also be seen as experts with special knowledge of what to do in such situations. We argue that this model presents significant advantages to deal with complex problems such as vibration surveillance.     

Implementation of the national cervical cancer screening in general practice and feasibility of a general practice-based call system: the GP''s opinion

A male fetus is described with multiple congenital abnormalities including craniosynostosis and bilateral radial aplasia. There are many similarities to the case recently reported by Imaizumi and Kuroki (Am J Med Genet 41: 162-163). These cases may represent a new syndrome with overlapping features of the Baller-Gerold and Roberts syndromes.