Microstructural evolution of bulk nanocrystalline Ni during creep

Experiments were conducted on electrodeposited (ED) nanocrystalline (nc) Ni with an average initial grain size of about 20 nm at 393 K to study the shape of the creep curves. In addition, microstructure was examined by means of transmission electron microscopy (TEM). The results show that the creep curves are characterized by the presence of a well-defined steady-state stage. An examination of the microstructure indicates that while grain growth occurs during deformation, the grain size attains a constant value once steady state creep is approached. A comparison between grain size measurements obtained by the TEM technique and those obtained via the X-ray diffraction method shows that the use of the latter method may lead to an underestimation of the value of the average grain size.     

Busulfan-based regimens and allogeneic bone marrow transplantation in patients with myelodysplastic syndromes

Preparative regimens containing busulfan (BU) followed by allogeneic bone marrow transplantation (BMT) were used in 27 consecutive patients with myelodysplastic syndromes (MDS). The median age was 33 years (range, 4 to 54). Ten were female and 17 male. Sixteen patients had primary MDS, 11 other patients had antecedent hematologic diseases or developed MDS after cytotoxic and/or radiation therapy. Six patients had leukemic transformation and received antileukemic therapy before BMT. Pre-BMT cytogenetic studies showed complex chromosomal abnormalities in 13 patients, a simple abnormality in 5 patients, and normal chromosome in 8 patients. Three BU-based preparative regimens were used: 1 patient received BU 4 mg/kg orally (PO) daily for 4 days and cyclophosphamide (CY) 50 mg/kg intravenously (IV) daily for 4 days (BUCY-4); 24 patients received BU 4 mg/kg PO daily for 4 days, cytosine arabinoside (ara-C) 2 g/m2 IV every 12 hours for 4 doses, and CY 60 mg/kg IV daily for 2 days (BAC); and 2 patients with preceding Fanconi anemia received BU 2 mg/kg PO daily for 4 days followed by total lymphoid irradiation of 5 Gy. Seventeen of 27 patients are alive with no evidence of disease. Ten patients have died: 2 from hepatic veno-occlusive disease, 3 from sepsis, 1 from a cerebral bleed, 1 from a massive gastrointestinal (GI) bleed associated with acute graft-versus-host disease, 1 from hemolytic uremic syndrome with adult respiratory distress syndrome, 1 from bronchiolitis obliterans, and the only patient who did not engraft died from acute myeloid leukemia. Regimen-related toxicities (RRT) include GI tract (diarrhea, 14; stomatitis, 11), liver (9), cardiac (1), and skin (5). Patients who received a genotypically matched marrow graft had a significantly better disease-free survival (DFS) than patients who received a nongenotypic marrow graft (P = .02). The Kaplan-Meier analysis projects an overall DFS of 56% +/- 13% and 78% +/- 10% for patients who received a genotypically matched marrow graft. With the exception of a child who did not engraft, there was no relapse of MDS or leukemia. Excellent DFS, acceptable RRT, and the ease of administration are advantages of this regimen.     

Mass Transport and Chemical Demixing of Y-Ba-Cu-O Compounds During Sintering in Temperature Gradients

A thin cylindrical powder compact (3-mm diameter by 20-mm) with a nominal composition of YBa₂Cu₃O_x was sintered in a static temperature gradient of 25°C/mm in air for 12 h. The temperature at the hot end of the sample was maintained at 940°±5°C. Considerable mass transport and chemical demixing occurred along the length of the sample. The results are consistent with the formation of a liquid phase at the hot end of the sample, transport of the liquid down the temperature gradient, and the formation of different eutectic compositions along the length of the sample. The implications for processing high-T_c superconductors in the system Y-Ba-Cu-O are discussed.     

An analysis of BioHashing and its variants

As a result of the growing demand for accurate and reliable personal authentication, biometric recognition, a substitute for or complement to existing authentication technologies, has attracted considerable attention. It has recently been reported that, along with its variants, BioHashing, a new technique that combines biometric features and a tokenized (pseudo-) random number (TRN), has achieved perfect accuracy, having zero equal error rates (EER) for faces, fingerprints and palmprints. There are, however, anomalies in this approach. These are identified in this paper, in which we systematically analyze the details of the approach and conclude that the claim of having achieved a zero EER is based upon an impractical hidden assumption. We simulate the claimants’ experiments and find that it is not possible to achieve their reported performance without the hidden assumption and that, indeed, the results are worse than when using the biometric alone.     

Microstructure,free amino acids and free fatty acids in Ras cheese

The physical state of the protein in Ras cheese has been followed by TEM and SEM in parallel with the chemical changes during maturation. The microstructure of young Ras cheese, by TEM, consists of casein micelles joined to form an open network, with some clustering of the micelles that appear, by SEM, as thin fibres aggregated into cross-linked elongated strands. At higher magnification, the casein fibres appear folded to include cavities.With further maturation to 4 months, the cheese matrix changed considerably by dissociation of the casein micelles to form a more homogeneous structure of sub-micelles, as seen by TEM, whilst SEM micrographs indicated that some protein fibres still existed.The protein breakdown, the accumulation of free amino acids and the liberation of free fatty acids in Ras cheese increased during maturation by decomposition of paracasein and cheese fat.Ras cheese is characterized as a compact body but can be viewed as an extensive inter-connection between the casein sheets in a cheese matrix and by a sharp flavour attributed to free glutamic acid and the presence of butyric, caprylic and caproic (free volatile) fatty acids.     

Ability of various proteins to form thermostable gels with propylene glycol alginate

Propylene glycol alginate forms gels with proteins in alkaline conditions (pH 9.3 to 10.5). The ability of gelatin, casein, soya isolate, whey protein concentrate, egg albumin and bovine serum albumin to form ‘protein-alginate’ gels was investigated. Conditions were varied so as to alter the structures of the protein and observe the effect on gel formation. These conditions include changing pH, heat, the action of nitrous acid, SDS, mercaptoethanol, hydrogen bond breakers and changing concentration of the protein. The extent of gel formation was indicated by its rigidity modulus. The tertiary structure of the protein appears to be a very important factor in the gel formation. The gels are readily brought down to pH values more suitable for foods, and are stable to heating at 95°C and to freeze-thawing.     

Nitriding of steels

The influence of nitriding temperature (900 to 1000°C) on the microstructure of low carbon steel and 304 stainless steel was studied. Nitriding was done in steps of 25°C with diffusion times between 3 and 9 hours. Metallographic technique was used to study the process kinetics. The case depth increases with temperature following an exponential relationship (parabolic). A quantitative relationship between diffusion layer thickening and nitriding temperature was determined.     

A review of spray-cooling and bottom-flooding work for lwr cores

Rewetting or the re-establishment of water films on the hot, fuel rod surfaces is of fundamental importance following a loss-of-coolant accident in a water cooled reactor. Two techniques are used: rewetting by a falling film of water (top sparay) and rewetting by an upflow of water (bottom flooding). Considerable theoretical and experimental work has been done to investigate the effects of different operating parameters on these techniques, and that work is summarized here.     

Study on radon and radon progeny in some living rooms

In the first part of this work, the potential alpha energy concentration (PAEC) of radon progeny, the equilibrium factor (F), the activity concentration of 222Rn gas (Co) and the unattached fraction (fp), were determined in 15 living rooms at El-Minia City, Egypt. The activity size distribution of (214)Pb was measured by using a low pressure Berner impactor. Based on the parameters of that distribution the total effective dose through the human lung was evaluated by using a dosimetric model calculation of ICRP. An electrostatic precipitation method was used for the determination of 222Rn gas concentration. The mean activity concentration of 222Rn gas (Co) was found to be 123 +/- 22 Bq m(-3). A mean unattached fraction (fp) of 0.11 +/- 0.02 was obtained at a mean aerosol particle concentration (Z) of (3.0 +/- 0.21) x 10(3) cm(-3). The mean equilibrium factor (F) was determined to be 0.35 +/- 0.03. The mean PAEC was found to be 37 +/- 8.1 Bq m(-3). The activity size distribution of (214)Pb shows mean activity median diameter of 290 nm with mean geometric standard deviation (sigma) of 2.45. At a total deposition fraction of approximately 23% the total effective dose to the lung was determined to be approximately 1.2 mSv. The second part of this paper deals with a study of natural radionuclide contents of samples collected from the building materials of those rooms under investigation given in part one of this paper. Analyses were performed in Marinelli beakers with a gamma multichannel analyser provided with a NaI(Tl) detector. The samples have revealed the presence of the uranium-radium and thorium radioisotopes as well as (40)K. Nine gamma-lines of the natural radioisotopes that correspond to 212Pb, 214Pb, 214Bi, 228Ac, 40K and 208Tl were detected and measured. The activity concentrations of 226Ra, 232Th and 40K were determined with mean specific activities of 65 +/- 22, 35 +/- 12 and 150 +/- 60 Bq kg(-1), respectively. These activities amount to a radium equivalent (Ra(eq)) of 126 Bq kg(-1) and to a mean value of external hazard index of 0.34.     

Investigation of the state of local thermodynamic equilibrium of a laser-produced aluminum plasma

In this work, the assumption of local thermodynamic equilibrium (LTE) for a laser-induced plasma in ambient air is examined experimentally using two different laser systems, namely an infrared short-pulse Ti : Sapphire laser and an ultraviolet long-pulse XeCl excimer laser. The LTE assumption is investigated by examining the plasma produced at a laser fluence of 10 J/cm(2) from aluminum targets containing iron and magnesium impurities. The excitation temperature is deduced from Boltzmann diagrams built from a large number of spatially integrated neutral iron lines distributed from 3.21 to 6.56 eV. It is shown that at any time after the end of the laser pulse, the neutral excited states are in excellent Boltzmann equilibrium. Detailed investigation of Boltzmann equilibrium further validates previous temperature measurements using less accurate diagrams. However, observations of ion lines provide some evidence that the ionized species do not obey Saha equilibrium, thereby indicating departure from LTE. This could be explained by the fact that the plasma cannot be considered as stationary for these species.