Al2TiO5–Al2O3–TiO2 nanocomposite: Structure,mechanical property and bioactivity studies

Novel biomaterials are of prime importance in tissue engineering. Here, we developed novel nanostructured Al₂TiO₅–Al₂O₃–TiO₂ composite as a biomaterial for bone repair. Initially, nanocrystalline Al₂O₃–TiO₂ composite powder was synthesized by a sol–gel process. The powder was cold compacted and sintered at 1300–1500 °C to develop nanostructured Al₂TiO₅–Al₂O₃–TiO₂ composite. Nano features were retained in the sintered structures while the grains showed irregular morphology. The grain-growth and microcracking were prominent at higher sintering temperatures. X-ray diffraction peak intensity of β-Al₂TiO₅ increased with increasing temperature. β-Al₂TiO₅ content increased from 91.67% at 1300 °C to 98.83% at 1500 °C, according to Rietveld refinement. The density of β-Al₂TiO₅ sintered at 1300 °C, 1400 °C and 1500 °C were computed to be 3.668 g cm^?3, 3.685 g cm^?3 and 3.664 g cm^?3, respectively.Nanocrystalline grains enhanced the flexural strength. The highest flexural strength of 43.2 MPa was achieved. Bioactivity and biomechanical properties were assessed in simulated body fluid. Electron microscopy confirmed the formation of apatite crystals on the surface of the nanocomposite. Spectroscopic analysis established the presence of Ca and P ions in the crystals. Results throw light on biocompatibility and bioactivity of β-Al₂TiO₅ phase, which has not been reported previously.     

Exploitation of parallel processing for implementing high-performance deduction systems

We describe a scheme for parallelizing first-order logic deduction systems. This scheme has been successfully used for parallelizing OTTER, which is a sequential deduction system developed at Argonne National Laboratory. This parallel deduction system, called PARRallel OTter-II (PARROT-II) has attained real speedups in excess of 20 over the best results of current sequential deduction systems. We believe that our results are of interest for two distinct reasons: (1) this is (as far as we know) the first case in which a system has successfully exploited parallelism to outperform the best sequential deduction systems on difficult problems, and (2) we believe that our approach generalizes to other deduction paradigms (e.g., term rewriting systems).This paper discusses the motivation for developing the scheme used by PARROT-II and the implementation details of PARROT-II. It also presents timing results for PARROT-II for some benchmark problems.Work submitted as partial fulfillment of the requirements for the doctoral degree at the Graduate College of the University of Illinois at Chicago. This work was supported in part by the Applied Mathematical Sciences subprogram of the Office of Energy Research, U.S. Department of Energy, under Contract W-31-109-Eng-38.     

Experience with not offering dialysis to patients with a poor prognosis

Despite ongoing discussion of dialysis rationing in the nephrology community, there are little available data describing current practice in treatment selection for very ill renal patients with a poor prognosis. We report a prospective survey of end-stage renal patients referred to our Canadian regional dialysis center who were not accepted to the dialysis program on the grounds of poor prognosis and low quality of life. One quarter of patients referred during 1992 were not accepted to the program, with a mean age of 74 +/- 11 years. Patients were predominantly female and most suffered from a combination of renovascular and cardiovascular disease, with very poor functional capacity as determined by the Karnofsky scale. Nonacceptance to the dialysis program did not create legal difficulties or requests for second opinions. Based on our experience, we propose guidelines for nonacceptance of patients to dialysis programs.     

Choice-sensitive health costs

Gemcitabine, a cytidine nucleoside analogue, has schedule-dependent antitumor activity in vitro and in vivo. Gemcitabine also has dose- and time-dependent radiosensitization properties in vitro. Thus it may have therapeutic application in combination with radiation. The aims of this study were to investigate whether gemcitabine could enhance radiation-induced tumor regrowth delay in a human squamous carcinoma (FaDu) xenograft in nude mice and to examine the effect of gemcitabine on radiation-induced apoptosis in in vivo tumors. Radiation was given locally to the tumors twice daily in 2 Gy fractions over 2 weeks for 5 days/week. Significant regrowth delay enhancement was observed which was dependent on gemcitabine schedule. Effective schedules using maximum tolerated gemcitabine doses were twice weekly and once weekly, but not daily. Significant toxicity occurred with radiation plus twice weekly gemcitabine, but enhancement was seen using gemcitabine doses well below the maximum tolerated dose. Both gemcitabine and radiation led to apoptotic cell death, but this was not increased when both treatments were combined. These results indicate that gemcitabine may be of therapeutic value as a radiation enhancer in the treatment of human cancers. Preliminary studies suggest that increased apoptotic cell death is not a mechanism leading to this enhancement.     

Drugs on a medical campus. III. Drug use among nursing and paramedical personnel

Fifty nurses and 50 paramedical staff working in the Rajendra Hospital and Medical College, Patiala, were studied by means of a structured, self-report questionnaire. The life-time prevalence of drug use among nurses was comparatively low--55%, compared to 81% among the paramedical staff. Current use of drugs as shown by the 30-day prevalence rate was also very low among the nurses, a majority of whom restricted themselves to using tranquillizers and sedatives for the specific purpose of relaxation or inducing sleep; only a few had experimented with alcohol, cannabis, and tobacco. On the other hand, the most commonly used drug among the paramedical personnel was alcohol, followed by sedatives, tranquillizers, cannabis and tobacco, most of them taking the drug for social reasons or for the thrills from the effects of the drug. This is also reflected in the comparatively higher number of paramedicals who felt that they would probably continue to use these drugs in the future, as also the fact that there were a few dependent users of opium and narcotics in this group.     

A preliminary report on the antiarrhythmic action of some newly synthesized glutarimide compounds

The effects of a new series of glutarimide compounds have been studied in acetylcholine induced auricular fibrillation in anaesthetized cats and epinephrine induced ventricular arrhythmmias in conscious pigeons. Some of the compounds showed varying degree of protective action against experimental arrhythmias. However these compounds were found to be less potent than quinidine. The mechanism of antiarrhythmic action has been discussed.     

Biocomposite formation using β-cyclodextrin as a biomaterial in poly(acrylamide-<Emphasis Type="Italic">co</Emphasis>-acrylic acid): preparation,characterization, and salinity profile

A biocomposite of poly(acrylamide-co-acrylic acid) hydrogel with β-cyclodextrin as a biomaterial was prepared through one-pot synthesis in water as a green solvent. The formation of biocomposite was confirmed by advanced techniques such as FTIR spectroscopy, XRD, DSC, TGA, and FE-SEM. In this report, straight forward and efficient synthetic protocol for biocomposite formation responded without any environmental hazard. Swelling capacity of P(AM-co-AA) and biocomposite was studied by addition of different saline solutions including monovalent, divalent, and trivalent salts. By addition of β-cyclodextrin, the swelling and saline water-absorbing properties of the biocomposite hydrogel were significantly improved. In this regard, the possible formation mechanism of the composite hydrogel is also discussed. It is deduced that the biocomposite formation can be the result of intermolecular interactions between polymer and β-cyclodextrin. The water-soluble polymer seems to have entered into the inner cavity of β-cyclodextrin to form supramolecular biocomposite structure. The results indicate that the order of water uptake decreases with increase in valency of the salts. It is believed that this is an effective method to prepare supramolecular biocomposite hydrogel materials. Its applications can be extended in marine water industries as a basis for antifouling coating, waste water treatment, and even in medical field. Hence, the synthesized materials can be biodegradable, environment-friendly, and biocompatible inspired by the green chemistry concept.     

Schiff Based Silatranyl Compounds Exhibiting ‘Fe3+ and Mn2+ Fluorescence Dual Ion Sensing and Antibacterial Activity’

Silicon - The synthesis of different Schiff base substituted silatranes (1c–4c) was carried out from the corresponding organotrimethoxysilanes (OTMS) (1b–4b) under anhydrous atmospheric...