Evolution of the Microstructure of Laser Powder Bed Fusion Ti-6Al-4V During Post-Build Heat Treatment

The microstructure of additively manufactured Ti-6Al-4V (Ti64) produced by a laser powder bed fusion process was studied during post-build heat treatments between 1043 K (770 °C) and just above the β transus temperature 1241 K (1008 °C) in situ using high-energy X-ray diffraction. Parallel studies on traditionally manufactured wrought and annealed Ti64 were completed as a baseline comparison. The initial and final grain structures were characterized using electron backscatter diffraction. Likewise, the initial texture, dislocation density, and final texture were determined with X-ray diffraction. The evolution of the microstructure, including the phase evolution, internal stress, qualitative dislocation density, and vanadium distribution between the constituent phases were monitored with in situ X-ray diffraction. The as-built powder bed fusion material was single-phase hexagonal close packed (to the measurement resolution) with a fine acicular grain structure and exhibited a high dislocation density and intergranular residual stress. Recovery of the high dislocation density and annealing of the internal stress were observed to initiate concurrently at a relatively low temperature of 770 K (497 °C). Transformation to the β phase initiated at roughly 913 K (640 °C), after recovery had occurred. These results are meant to be used to design post-build heat treatments resulting in specified microstructures and properties.

     

A new method for quantitative regional cerebral blood volume measurements using computed tomography

BACKGROUND AND PURPOSE: Knowledge of cerebral blood volume (CBV) is invaluable in identifying the primary cause of brain swelling in patients with stroke or severe head injury, and it might also help in clinical decision making in patients thought to have hemodynamic transient ischemic attacks (TIAs). This investigation is concerned with the development and clinical application of a new method for quantitative regional CBV measurements. METHODS: The technique is based on consecutive measurements of cerebral blood flow (CBF) by xenon/CT and tissue mean transit time (MTT) by dynamic CT after a rapid iodinated contrast bolus injection. CBV maps are produced by multiplication of the CBF and MTT maps in accordance with the Central Volume Principle: CBV = CBF x MTT. The method is rapid and easily implemented on CT scanners with the xenon/CBF capability. It yields CBV values expressed in milliliters of blood per 100 grams of tissue. RESULTS: The method was validated under controlled physiological conditions causing changes that were determined both with our technique and from pressure-volume index (PVI) measurements. The two independent estimates of CBV changes were in agreement within 15%. CBV measurements using this method were carried out in normal volunteers to establish baseline values and to compare with values using the ratio-of-areas method for calculating both CBF and CBV from the dynamic study alone. Average CBV was 5.3 mL/100 g. The method was also applied in 71 patients with severe head injuries and in 1 patient with hemodynamic TIAs. CONCLUSIONS: The primary conclusions from this study were (1) the proposed method for measuring CBV accurately determines changes in CBV; (2) the MTT x CBF determinations are in agreement with the ratio-of-areas method for CBV measurements in normal volunteers and are consistent with other methods reported in the literature; (3) MTTs are significantly prolonged early after severe head injury, which when combined with the finding of decreased CBF and increased arteriovenous difference of oxygen indicates increased cerebrovascular resistance due to narrowing of the microcirculation consistent with the presence of early ischemia; and (4) CBV in the patient with TIAs was increased in the hemisphere with the occluded internal carotid artery, indicating compensatory vasodilation and probable hemodynamic cause.     

Tuberculosis of the sacroiliac joint

A 23-year-old woman presented with low back pain of several months' duration. A tuberculous infection of the left sacroiliac joint was diagnosed by closed-needle biopsy. The clinical presentation, radiological features and outcome of this patient are discussed.     

The use of the universal theory of hygienic standards in military hygiene

On the basis of an abound practice of hygiene standardization, the authors have elaborated a system of fundamental tenets and premises that correspond to the requirements of a universal theory. It includes norms and standards for a living organisms and the environment. The hygiene standardization foundation is based on the principles of guarantee, social-biological balance, complex and dynamics. The tenets stated in the article confirm interrelation and character of the hygiene standards theory formulation and its prognostic function.     

Voltage-dependent effect of Al3+ on channel activities in hippocampal neurons

The world's great wines are produced from a relatively small number of classic European cultivars of Vitis vinifera L Most are thought to be centuries old and their origins have long been the subject of speculation. Among the most prominent of these cultivars is Cabernet Sauvignon, described as "the world's most renowned grape variety for the production of fine red wine". Although now grown in many countries, Cabernet Sauvignon derives its fame from its long association with the Bordeaux region of France, where it has been grown at least since the 17th century. We present microsatellite DNA evidence for the hypothesis that Cabernet Sauvignon is the progeny of two other Bordeaux cultivars, Cabernet franc and Sauvignon blanc. Likelihood ratios support this hypothesis to a very high degree of probability. A close relationship between Cabernet Sauvignon and Cabernet franc has been suspected but the genetic contribution of Sauvignon blanc, despite its similar name, is a surprise.     

NDR1, a pathogen-induced component required for Arabidopsis disease resistance

Plant disease resistance (R) genes confer an ability to resist infection by pathogens expressing specific corresponding avirulence genes. In Arabidopsis thaliana, resistance to both bacterial and fungal pathogens, mediated by several R gene products, requires the NDR1 gene. Positional cloning was used to isolate NDR1, which encodes a 660-base pair open reading frame. The predicted 219-amino acid sequence suggests that NDR1 may be associated with a membrane. NDR1 expression is induced in response to pathogen challenge and may function to integrate various pathogen recognition signals.     

Effect of the mycotoxins penitrem, paxilline and lolitrem B on the electromyographic activity of skeletal and gastrointestinal smooth muscle of sheep

Myasthenia gravis (MG) is mediated by autoantibodies against the acetylcholine receptor at the muscle endplate. Some MG patients have in addition antibodies (Ab) to the skeletal muscle proteins ryanodine receptor (RyR) and titin. We have examined GM and KM allotypes, RyR and titin Ab in 44 MG patients (37 thymoma patients and 7 non-thymoma, late-onset patients) and 292 non-MG controls to see if GM/KM allotypes associate with differences in autoantibody production. All patients had titin Ab, and 15 thymoma patients had also RyR Ab. The phenotype GM 1, 2, 3 23 5, 21 was significantly increased in the patients with titin Ab compared with the non-MG controls (chi2 = 4.93, p < 0.05). Thymoma patients with RyR Ab had a higher frequency of the GM 3 23 5 phenotype compared with RyR Ab negative patients and controls (chi2 = 7.1, p < 0.05). KM allotypes did not differ between RyR Ab positive or titin Ab positive patients and controls. GM phenotypes may thus be associated with an autoimmune response against the muscle proteins titin and RyR in MG patients.     

Consideration on a case of carcinoma ex pleomorphic adenoma of the parotid gland

The authors report a case of carcinoma in an ex pleomorphic adenoma of the parotid gland that was recently referred to their attention. This form of carcinoma is not very frequent and in the literature it is reported in a percentage of cases ranging from 1.5 to 12%. The pathogenesis of this neoplasia is controversial and at the present state of the art there are authors who support the hypothesis of a malignant transformation of a previous pleomorphic adenoma, and those who sustain the onset of the tumour ex novo. At present, there is a tendency to differentiate the carcinoma ex pleomorphic adenoma from the malignant mixed tumour: the histological analysis of the former in fact shows a benign stromal component typical of pleomorphic adenoma associated with a malignant epithelial component, whereas in the malignant mixed tumour both the mesenchymal and epithelial components are malignant. The authors use this case report as a starting point to review their 20-year experience, of pleomorphic adenoma in order to evaluate the behaviour of this tumour, above all in relation to the phenomenon of recidivation and cancerization. They report recidivation in 3.5% of cases and no malignant degeneration. The surgical approach used varied depending on the site and size of the neoformation, as well as on whether the tumour was primary or recurrent.     

Quantitative salivary gland scintigraphy--a recommended examination prior to and after radioiodine therapy

Thrombotic thrombocytopenic purpura (TTP) is a syndrome characterised by the clinical pentad of microangiopathic haemolytic anaemia (MAHA), thrombocytopenia, renal failure, fluctuating neurologic signs, and fever. The aetiology of TTP is unknown, but associations with various underlying diseases, infections and drugs have been identified. One of these associations is with HIV infection. We describe the clinical picture, the laboratory results and the response to plasma therapy of two cases of HIV-associated TTP. In both patients, a longitudinal semiquantitative assessment of the numbers of schistocytes in blood was made, which correlated well with the more traditional parameters of disease activity. Since 1987, at least 49 patients with HIV-associated TTP have been reported. A case-analysis of the 38 patients who were described in sufficient detail and a review of the literature in the setting of HIV infection is presented. The most important conclusions from these combined data are: (1) TTP usually seems to occur in patients with a CD4+ lymphocyte count < 250 x 10(6).l(-1); (2) more than 50% of the patients present with TTP soon after or during an infectious or malignant disease; (3) plasma exchange is the therapy of choice, still resulting in mortality of 22%; (4) higher initial platelet count and creatinine level are correlated with an adverse outcome.     

Bismuth carbomer foam enemas for active chronic pouchitis: a randomized, double-blind, placebo-controlled trial

One biological effect of nitric oxide (NO) has been believed to be exerted through induction of the ADP-ribosyltransferase activity of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Though this notion is based on the finding that NO increases the auto-ADP-ribosylation of GAPDH, controversial data have also been reported. To determine whether or not NO really activates ADP-ribosylation, we re-examined the NO-induced modification of GAPDH with NAD+. GAPDH was modified equally with [adenosine-14C]NAD+ and [carbonyl-14C]NAD+, indicating that the glycoside bond of NAD+ between ADP-ribose and nicotinamide is intact. The release of nicotinamide from NAD+ was not evident during incubation of GAPDH with [carbonyl-14C]NAD+. Thus, the modification of GAPDH is apparently not ADP-ribosylation. In addition, we found that basal and glyceraldehyde-3-phosphate-induced modifications of GAPDH, both of which have also been explained as ADP-ribosylation, were not ADP-ribosylation, and that the modification of GAPDH in the absence and presence of NO or GA3P was distinct in the dithiothreitol effect or resistance to HgCl2.