Synthesis and regeneration of reactive polymers bearing triphenylphosphine dichloride functional groups using triphosgene

Summary A new methodology is described for the synthesis of reactive polymers bearing triphenylphosphine dichloride groups by the use of triphosgene. These materials show high reactivity for the room temperature conversion of benzyl alcohol to benzyl chloride. In one hour, yields higher than 90% were achieved using reactive copolymers with up to 25 w% divinylbenzene (DVB). The functional groups can be easily and efficiently regenerated using 1.0 mol of triphosgene for every 2.6 moles of phosphine in the polymer. Preliminary results showed up to 40% conversion of benzyl alcohol in column reactions using regenerated polymers at 5 to 10 min contact times.     

An experimental investigation of the effect of coatings and cutting parameters on the dry drilling performance of aluminium alloys

As a result of the need to automate assembly in the aircraft industry, along with economic and ecological reasons, industry and research institutions have been pushed to develop dry drilling for aluminium alloys to eliminate the need for cooling fluids. The main difficulties in dry drilling are accelerated tool wear due to workpiece material adhesion on the tool and the formation of bigger-sized burrs. This paper describes an experimental research study on machinability in the dry drilling of aluminium alloys and on the potential of the new design of tools and coatings. Dry drilling tests were performed using uncoated drills and two different coatings produced by means of an arc evaporation PVD process. Experiments consisted of machining with a 10-mm diameter three-edged drill to produce 25-mm deep holes. Tool wear evolution and burr size were analysed, as well as the impact of the process parameters on torque, power, feed force and tool temperature.     

Preliminary studies on the influence of boron on the foliar biomass and quality of tobacco leaves subjected to $\hbox{NO}_3^-$ fertilisation

The aim of the present work was to determine the influence of different B dosages on foliar biomass and quality in tobacco plants (Nicotiana tabacum L var Tennesse 86). Tobacco plants were grown under controlled conditions and submitted to regular fertilisation with macro‐ and micronutrients. The B was applied to the nutrient solution in the form of H₃BO₃ at 5 µM (B1), 10 µM (B2) and 20 µM (B3). The results indicated that under the experimental conditions of this work the increased application of B favoured the growth and development of the leaves, this leading to improved biomass production in tobacco leaves. The increase in foliar biomass in treatment B3 is due largely to the stimulation of assimilation. However, this situation has negative consequences for tobacco quality, given that the B3 treatment augmented the concentration as well as the foliar concentration of nicotine, both effects being harmful for human consumption. Finally, a close and directly proportional relationship was found in our experiment between the parameters foliar biomass production, total N concentration, chlorophyll concentration and decline in quality. © 2001 Society of Chemical Industry     

Exergy and exergoeconomic analysis of a crude oil combined distillation unit

The combined distillation unit is the first plant in a crude oil refinery, in which several intermediate products, i.e. liquid petroleum gas (LPG), naphtha, jet fuel, kerosene, diesel fuel, gas oils and reduced crude, are obtained through atmospheric and vacuum distillation of the crude oil mixture. It is important to determine the critical points in the unit from the exergy view point and to properly allocate the total production cost to the different simultaneously produced streams, to determine the monetary flows all through the plant, and to state the relevance in economic terms of the exergy losses of each individual equipment item. The results of the exergy and exergoeconomic analyses are presented in this paper. The most important factor affecting the transformation, operation and production costs of the products is the cost of the crude oil raw material; utilities, salaries, maintenance and even capital investment costs are less important. Also the critical points of the plant are presented which provide the basis for the optimization of the unit showing additional opportunities for process integration.     

Deoxypyridinoline and other biochemical markers of bone resorption in distinct pathologies

Collagen type 1 represents more than 90% of bone matrix. Therefore, quantitation of collagen crosslinks, such as deoxypyridinoline, can provide information on bone resorption degree. An evaluation was made of deoxypyridinoline as well as other bone markets, such as alkaline phosphatase, tartrate resistant acid phosphatase, and hydroxyproline in patients with the diagnosis of osteoporosis. Paget's disease, hyperthyroidism, and chronic renal failure on haemodialysis or not. Deoxypyridinoline levels were significantly increased in patients with osteoporosis, Paget's disease, and hyperthyroidism. Hydroxyproline levels were increased in patients with Paget's disease, and tartrate resistant acid phosphatase was increased in all the entities studied. Deoxypyridinoline can be a more sensitive marker than hydroxyproline, with some advantages, such as its quantitation in a urine specimen and its high bone specificity. In patients with renal failure, tartrate resistant acid phosphatase was the only biochemical marker of bone resorption with increased levels.     

Temperature variation of optical energy gap values of the compound CuGaTe2

Measurements of optical absorption in the temperature range 20 to 300K were made on polycrstalline samples of the compound CuGaTe₂. These results were used to determine values of the optical energy gap E_g as a function of temperature T. The resulting curves of E_g vs T were fitted to a simplified Manoogian-Leclerc equation and the fitted coefficients used to give values of (dE_g/dT)₁ and (dE_g/dT)₂, due to lattice dilation and electron-phonon contributions, respectively. Hence, the deformation potentials of the valence and conduction bands were estimated for the present compound.     

Clinicopathologic study of probable Alzheimer disease: assessment of criteria for excluding cerebrovascular disease

The National Institute of Neurological and Communicative Disorders and Stroke/Alzheimer Disease and Related Disorders Association criteria for probable Alzheimer disease (AD) require exclusion of non-AD dementia-producing conditions but do not specify how the non-AD conditions are to be identified. We addressed this issue for the case of cerebrovascular disease (CVD) by defining exclusion rules based on commonly described clinical features: (a) history of strokelike episodes; (b) history of stepwise cognitive decline; (c) focal deficits on neurological examination; and (d) evidence of significant CVD on neuroimaging. We applied these rules retrospectively to clinical records for 92 cognitively impaired patients who otherwise met criteria for probable AD and whose brains were subsequently available for postmortem examination. We used Fisher's exact test to assess the effectiveness of the exclusion rules in predicting the presence of CVD on autopsy. Prediction was better than chance when all four clinical features were used together (p = 0.0008) and when the stepwise decline or neuroimaging criteria were used alone (p = 0.03 and p = 0.05, respectively). Overall, the CVD exclusion rules were deficient because of low accuracy (50.0%) and low sensitivity (52.6%). These results support provisional use of the CVD criteria chosen for this study but suggest that modifications are needed for acceptable diagnostic accuracy and sensitivity to be achieved.     

Hypothalamic-pituitary-adrenal axis function and prolactin secretion in systemic lupus erythematosus

Continued improvement in the computer price-to-performance ratio and the adoption of international standards have enhanced the feasibility of completely digital echocardiographic laboratories that were initially described more than a decade ago. Digital archival has distinct advantages over analog recording, including improved laboratory efficiency, capability of side-by-side comparison of current and historical studies, streamlined image storage, and enhanced interinstitution image transfer. Studies have demonstrated that clinical and electronic image compression allows efficient storage of data, without affecting diagnostic accuracy. Finally, digital echocardiography has important telemedicine applications.