Influence of chain length on the rate of hydrolysis of polyoxymethylene ethers

Four series of polyoxymethylene ethers (polyformals) [RO(CH₂O)_nR] where R is isopropyl, ethyl, methyl, or methoxyethyl and n = 1–3 have been prepared, examined by GLC, separated by fractional distillation, and characterized by NMR. Rate constants for the aqueous acid hydrolysis of all the compounds have been determined. The isopropyl series appears to be a special case, and as reported in the literature (but in aqueous dioxane), all members of this series hydrolyze at the same rate. In the other series, there is a definite increase in rate, which never exceeds fourfold, in going from n = 1 to n = 2. This increase differs considerably from the 100-fold increase reported by others in going from CH₃OCH₂OCH₃ to CH₃O(CH₂O)₂CH₃. In all series, the n = 3 compound hydrolyses at practically the same rate as the n = 2 compound.     

A logical model of cooperating rule-based systems

The model described in this paper is intended to assist in the planning, specification, development, and verification of space information systems involving distributed rule-based systems. The model is based on an analysis of possible uses of rule-based systems in control centers. We summarize this analysis in the form of a data flow model of a hypothetical intelligent control center. From this data flow model we abstract the logical model of cooperating rule-based systems, which consists of four layers of increasing capability: 1) communicating agents, 2) belief-sharing knowledge sources, 3) goal-sharing interest areas, and 4) task-sharing job roles. We describe the functions, key knowledge elements, and required reasoning capabilities at each layer.     

Preparation of adherent films of poly-p-xylylenes on aluminum by electrolysis

The electrolysis of solutions of p-methylbenzyltrimethylammonium nitrate or, better, p-xylylenebis(trimethylammonium nitrate) or p-xylylenebis(triphenylphosphonium chloride or bromide) in a polar organic solvent with an aluminum cathode and a platinum anode results in the formation of adherent coatings of poly-p-xylylene on the cathode. The mechanism of this reaction involves the electrochemical generation of p-xylylene and its subsequent polymerization on the aluminum cathode. Competing reactions are formation of p-xylene and reduction of the solvent.     

Nigrostriatally induced motor reactions in the rat. I. Rotational behavior and posture asymetry after intracerebral injection of apomorphine and dopamine

Using a rotameter described by Ungrstedt, the influence of pretreatment with 6-hydroxy-dopamine and transections of the Capsula interna on the asymmetry of the animal's poise and movement following systemic and intracerebral administration of dopamine and apomorphine was studied. After lesion of the nigrostriatal tract, i.p. administered apomorphine caused the animals to rotate towards the damaged side. After injection of apomorphine in the Nucleus caudatoputamen of healthy animals, initial rotations towards the injection side with subsequent opposite rotation were observed, whereas dopamine injected into the Nucleus caudatoputamen and the Substantia nigra initiated rotations in contralateral direction only. Pretreatment with haloperidole nullified the effect of apomorphine. The results have proved the effectiveness both in the Nucleus caudatoputamen and the Substantia nigra of drugs stimulating the dopamine receptors. With intact rats, the two sides of the nigrostriatal system are functionally asymmetric, which is reflected by the quantitative differences of responses following stimulation of dopamine-sensitive receptors and the individually different preference of one rotational direction. These individual behavioural patterns are modified by experimental influences.     

Colony-forming ability of ultraviolet-irradiated xeroderma pigmentosum fibroblasts from different DNA repair complementation groups

In two related studies, a combination of reinforcement for incompatible behavior and positive practice overcorrection was applied to the elimination of head-slapping and head-banging behavior exhibited, respectively, by two profoundly retarded boys. The design for both studies also included a period in which only reinforcement for incompatible behavior was applied. The results from Study 1 indicated that, while reinforcement had little effect in reducing the frequency of the learner's head slapping, the combination of reinforcement and overcorrection had an immediate effect in significantly reducing and eventually eliminating that behavior. A 4-month follow-up indicated no significant recurrence of the behavior. In Study 2, on the other hand, both reinforcement and the combination of reinforcement and overcorrection resulted in a significant increase in the frequency of the learner's head-banging behavior. Discussion centered on several research questions left unanswered by the differing effects of the procedures applied in both studies.     

Analysis of dose, dose-rate and treatment time in the production of injuries by radium treatment for cancer of the uterine cervix

A retrospective study has been made of 15 patients who had developed severe complications to the bladder, rectum and ureters after radiation therapy for carcinoma of the cervix. Comprehensive dose distribution in the pelvis were calculated with computer assistance to visualize how the normal organs had been irradiated. The risk of normal tissue injury was analysed graphically with respect to the maximum radium dose, dose-rate and irradiation time. The two groups of data representing the injured and non-injured organs separate much better in a dose-rate versus dose plot than in a conventional Strandqvist type dose-time plot. This implies that in radium therapy, the dose-rate rather than the treatment time, is the important parameter in modifying the risk of normal tissue injury. Our results show a good separation of injured from non-injured cases only when the maximum values of dose and dose-rate were used. This suggests that clinically significant injury may develop from relatively small regions of high dose and dose-rate. Since the dose-rate varies from point to point in the pelvis (unlike treatment time), comprehensive determinations of dose-rate distributions are required in order to locate the sites of potential injuries.     

Prolonged extracorporeal membrane oxygenation in the treatment of burns-induced shock lung (authors transl)

A case of third-degree burns involving 35 per cent of the body surface is reported with occurred in a 28-year-old man. On the 6th day progressive pulmonary insufficiency developed which 3 days later necessitated extracorporeal membrane oxygenation. Oxygen diffusion capacity gradually improved and the patients resumed spontaneous respiration with oxygen enriched air. He died 5 days after membrane oxygenation was discontinued due to massive haemorrhages from an infection at the site of the femoral by-pass. The technique adopted for the perfusion, which lasted 83 hours, is described.     

Locus of control and interpersonal evaluations.

21 male and 21 female undergraduates took Rotter's internal-external (I-E) scale, then participated in a group test with 2 peers during which they exchanged evaluations of one another's answers. The evaluations Ss received were experimentally controlled so that they received mostly positive evaluations from 1 peer (positive evaluator) and mostly negative evaluations from the other peer (negative evaluator). As a manipulation of the perceived controllability of others' evaluations, 1/2 of the Ss were told that the test measured an ability and that there were right and wrong answers to the items (ability condition), and 1/2 were told that the answers represented personal opinions and that there were no right and wrong answers (opinion condition). Differences in Ss' evaluations of the answers given by the positive and negative evaluators showed that externals reciprocated more than internals and that this difference tended to be stronger in the opinion condition than in the ability condition. (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)