High-strength corundum ceramics with a lowered sintering temperature

Factors affecting the sintering, formation of a fine crystalline structure, and strength of aluminum oxide ceramics are considered. A ceramics with a strength of up to 600 MPa fabricated at 1450°C in an air medium has been presented. It is shown that the sintering temperature of ceramics based on Al₂O₃ (including -Al₂O₃) can be decreased to 1200°C.Translated from Ogneupory i Tekhnicheskaya Keramika, No. 10, pp. 2 – 5, October, 1996.     

Nonstationary nonisothermal flow of gas mix in offshore gas pipelines

This article presents a mathematical model of the shock-free unsteady nonisothermal turbulent flow of a viscous nonideal chemically inert multicomponent gas mix in the offshore circular cross-section gas pipeline with a rigid multilayer coating. The calculations of flow characteristics are given for the problem of the pipeline’s shift to the periodic condition under a periodic change of the consumption rate at the right end.     

Modeling organizational performance indicators

Performance measurement and analysis is crucial for steering the organization to realize its strategic and operational goals. Relevant performance indicators and their relationships to goals and activities need to be determined and analyzed. Current organization modeling approaches do not reflect this in an adequate way. This paper attempts to fill the gap by presenting a framework for modeling performance indicators within a general organization modeling framework.     

Influence of patient caregivers on course of patient illness: "expressed emotion" and alternative measures

The influence of the quality of care that patients receive during the course of their illness has been the subject of special scrutiny in the area of mental health. The concept of "expressed emotion" (EE) evolved in an effort to understand the impact of family and social environment on the vulnerability to relapse of schizophrenic patients. A semistructured interview, the Camberwell Family Interview, was developed to assess expressed emotion. This article examines the historical context, generalizability, methodological strengths and limitations of the construct of EE and the Camberwell Family Interview, as well as the nature and effects of treatment intervention programs designed to neutralize adverse effects of patient caretaker attitudes.     

Reduction of disulfide bonds in an amyloidogenic Bence Jones protein leads to formation of "amyloid-like" fibrils in vitro

Motivated by the finding that the amino acid sequence of the Bence Jones protein BJP-DIA was identical to that of the main protein component of the amyloid fibrils obtained from the same patient with AL-amyloidosis, (Klafki, H.-W., Kratzin, H.-D., Pick, A.-I., Eckart, K., Karas, M. & Hilschmann, N. (1992) Biochemistry 31, 3265-3272.), we attempted to create "amyloid-like" fibrils from the Bence Jones protein in vitro, without addition of proteolytic enzymes. Reduction of BJP-DIA, solubilized in PBS, pH 7.4, overnight at 37 degrees C resulted in the formation of a precipitate which had affinity for the dye Congo red. Electron microscopy of negatively stained samples of the reduced protein revealed aggregates of linear unbranched fibrils. SDS-polyacrylamide gel electrophoresis demonstrated that the precipitate consisted almost exclusively of intact light chain molecules. This result makes it possible to deduce a molecular model of these amyloid fibrils generated in vitro.     

Muscle proton T2 relaxation times and work during repetitive maximal voluntary exercise

We studied the effects of progressive maximal voluntary handgrip contractions (MVCs) on muscle proton spin-spin (T2) relaxation times and work, measured as the integrated force vs. time curve (FTI). Six healthy volunteers performed 10, 20, 40, and 80 MVCs in a 0.35-T magnet on four separate occasions. Repeated measures analyses of variance of increases in T2 and FTI during successive bouts were significant (P < 0.005 and P < 0.001, respectively). FTI increased with successive bouts to a greater extent than did muscle T2 (P < 0.05). For T2, the Helmert contrast judged the 10-MVC response lower than the mean of the remaining responses (P < 0.005), and the differences between all others compared with the means of subsequent responses were not significant, indicating a "flattening" of the T2 response after the increase from 10 to 20 repetitions. For FTI, all the single degree of freedom Helmert contrasts were significant (P < 0.001), indicating a continual increase in response over increased MVCs. The curved nature of the T2 response conformed best to a hyperbolic function, suggesting that a limit of approximately 32% exists for the change in T2 during progressively longer bouts of MVCs. A limit in the T2 response is consistent with the existence of a limit in the amount of water that muscle can take up from the vasculature during exertion.     

Phase diagram of the LaFeO3-LaSrFeO4 system

The phase relationships in the LaFeO₃-LaSrFeO₄ system at temperatures in the range 1000–2100°C in air are investigated, and the phase diagram of the system is constructed. One perovskite-like compound, namely, La₂SrFe₂O₇, which belongs to the Ruddlesden-Popper phases, is revealed in the system.     

Inhibition of HeLa cell messenger RNA translation by 7-methylguanosine 5'-monophosphate

Translation of HeLa cell RNA containing poly(A) in a wheat germ cell-free system is markedly but incompletely inhibited by 7-methylguanosine 5'-monophosphate (m7G5'p). We have analyzed the translation products synthesized in the presence of different concentrations of m7G5'p and find that translation of all mRNAs is equally inhibited. To demonstrate the specificity of the inhibitor for RNAs with 5'-terminal m7G5' ppp... we show that specific translation products of satellite tobacco necrosis virus RNA, which does not have this 5' terminus, are synthesized in the presence of m7G5' p. Protein synthesis programmed by endogenous mRNA in a HeLa cell-free system is inhibited after a 10-min lag by m7G5' p. Other guanosine nucleotides without the 7-methyl group or with the phosphate in a different position are not inhibitor. We show that translation of all mRNAs is inhibited to a similar extent by m7G5'p in the HeLa cell-free system, by synthesizing 35S-labeled proteins in the presence of different inhibitory concentrations of this nucleotide and analyzing the translation products by electrophoresis and autoradiography. Translation of encephalomyocarditis virus RNA added to the HeLa cell-free system is not inhibited by m7"g5p; this viral RNA does not have this nucleotide at the 5' terminus. This indicates that m7G5'p specifically inhibits translation of mRNAs with the 5' terminus m7G5'ppp... and suggests that initiation of translation of picornavirus RNA may proceed via a mechanism different from that of cellular mRNAs.     

Relationship of passive cigarette-smoking to sudden infant death syndrome

The smoking habits of 56 families who lost babies to the sudden infant death syndrome (SIDS) were compared to those of 86 control families. A higher proportion of SIDS mothers smoked both during pregnancy (61% vs. 42%) and after their babies were born (59% vs. 37%). SIDS mother also smoked a significantly greater number of cigarettes than controls. Exposure to cigarette smoke ("passive smoking") appears to enhance the risk of SIDS for reasons not known.