Primary beneficiation of tantalite using magnetic separation and acid leaching

Primary beneficiation was successfully performed prior to dissolution of manganotantalite （sample A） and ferrotantalite （sample C） samples obtained from two different mines in the Naquissupa area, Mozambique. Magnetic separation removed the majority of iron and titanium, whereas H2SO4 leaching removed a large portion of thorium and uranium in these samples. Analytical results indicated that 64.14wt% and 72.04wt% of the total Fe and Ti, respectively, and -2wt% each of Nb205 and Ta205 were removed from sample C （ferrotantalite） using the magnetic separation method, whereas only 9.64wt% and 8.66wt% of total Fe203 and TiO2, respectively, and -2wt% each of NbEOs and Ta2O5 were removed from sample A （manganotantalite）. A temperature of 50℃ and a leaching time of 3 h in the presence of concentrated HESOa were observed to be the most appropriate leaching conditions for removal of radioactive elements from the tantalite ores. The results obtained for sample A under these conditions indicated that 64.14wt% U3O8 and 60.77wt% ThO2 were leached into the acidic solution, along with 4.45wt% and 0.99wt% of Nb2O5 and Ta2O5, respectively.     

Internal flows which transist from turbulent through intermittent to laminar

A transition model for internal flows which enables the prediction of the change of flow regime from turbulent through intermittent to laminar has been implemented by numerical simulation. This model had previously been demonstrated to be effective for the prediction of the breakdown of an initially laminar internal flow and its subsequent transitions to either intermittent or turbulent states. The model was employed here to study a flow which is decelerated by passing through a conical diffuser. The flow enters the diffuser with a fully developed turbulent velocity profile and exhibits transitions either in the diffuser or in a pipe situated downstream of the diffuser exit. The presence or absence of flow separation affected the onset of laminarization. Proof that laminarization actually occurred is provided by the values of the fully developed friction factors in the pipe downstream of the exit of the diffuser. These friction factors spanned the range from pure laminar flow through intermittent flow to fully turbulent flow. Comparisons were made with established benchmarks for each of these three flow regimes.     

Studies of the copolymerisation of acrylic acid with n‐butyl vinyl ether

BACKGROUND: Copolymers of acrylic acid (AA) are important materials for the preparation of glass ionomer cements. Copolymerisation of AA is widely used to alter the acid strength of the material and to increase the number of salt bridges formed in cements. In this paper we report the copolymerisation of AA with n‐butyl vinyl ether (BVE) to form unique copolymers of the hemiacetal ester and with BVE incorporated into the main chain. RESULTS: AA and BVE undergo a spontaneous reaction to form a hemiacetal ester which can itself undergo free radical copolymerisation. The kinetics of this reaction in the bulk state have been examined. In addition, under these conditions BVE is incorporated into the polymer main chain via a free radical mechanism. CONCLUSION: Novel copolymers of the hemiacetal ester and BVE have been prepared in this study. The hemiacetal side chains are labile under moderate heating, being converted back to the acid analogue. Copyright © 2009 Society of Chemical Industry     

Determinant spreading associated with demyelination in a nonhuman primate model of multiple sclerosis

Definition of the immune process that causes demyelination in multiple sclerosis is essential to determine the feasibility of Ag-directed immunotherapy. Using the nonhuman primate, Callithrix jacchus jacchus (common marmoset), we show that immunization with myelin basic protein and proteolipid protein determinants results in clinical disease with significant demyelination. Demyelination was associated with spreading to myelin oligodendrocyte glycoprotein (MOG) determinants that generated anti-MOG serum Abs and Ig deposition in central nervous system white matter lesions. These data associate intermolecular "determinant spreading" with clinical autoimmune disease in primates and raise important issues for the pathogenesis and treatment of multiple sclerosis.     

Long-term expression and secretion of human glucocerebrosidase by primary murine and human myoblasts and differentiated myotubes

The majority of studies dealing with DNA analyses are made on fixed cells. In this context, the efficiency as fixatives of ethanol, methanol, acetone, Carnoy, Boehm-Sprenger and aldehydes was determined using two different DNA fluorescent probes, Hoechst 33342 and propidium iodide. The purpose of our study was to find the fixative that would provide the best results with respect to the following parameters: aggregates, cell size and granularity, and DNA staining analysis. Using murine fibroblasts, we found that 68% ethanol, 85% methanol and aldehydes did not increase aggregate formation, whereas Carnoy, acetone or Boehm-Sprenger fixatives did. The results show that aldehydes seem to alter cell size least. All fixatives induce an increase in cell granularity, which is very pronounced with alcohols, but aldehydes alter morphology less than alcohols. We observed that the fixatives giving the best resolution with Hoechst 33342 staining lead to a lower measurement variability than with propidium iodide staining. This study leads us to conclude that 68% ethanol and 85% methanol can be considered as appropriate fixatives for flow cytometry studies of DNA content.     

Association of glyceraldehyde-3-phosphate dehydrogenase expression with cell motility and metastatic potential of rat prostatic adenocarcinoma

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression is increased in Dunning R-3327 rat prostatic adenocarcinoma cell lines relative to normal rat ventral prostate tissue. GAPDH expression closely correlates with cell motility of Dunning prostate cancer cell lines and accurately distinguishes cell lines with high metastatic potential from those with low metastatic potential. Increased GAPDH expression in the cancer cell lines is not simply related to increased growth rate, since rapidly proliferating normal prostate tissue did not exhibit elevated GAPDH expression.     

Long-term T cell memory requires the surface expression of self-peptide/major histocompatibility complex molecules

How memory T cells are maintained in vivo is poorly understood. To address this problem, a male-specific peptide (H-Y) was identified and used to activate female anti-H-Y T cells in vitro. Anti-H-Y T cells survived in vivo for at least 70 days in the absence of antigen. This persistence was not because of the intrinsic ability of memory T cells to survive in vivo. Instead, the survival and function of adoptively transferred memory cells was found to require transporter of antigen protein 1-dependent expression of self-peptide/major histocompatibility complex class I molecules in recipient animals. Therefore, it appears that the level of T cell receptor engagement provided by transporter of antigen protein 1-dependent, self-peptide/major histocompatibility complexes is sufficient to maintain the long-term survival and functional phenotype of memory cells in the absence of persistent antigen. These data suggest that positive selection plays a role not only in T cell development but also in the maintenance of T cell memory.     

In vitro antimycobacterial activity of 5-chloropyrazinamide

5-Chloropyrazinamide and 5-chloropyrazinoic acid were evaluated for in vitro activity against Mycobacterium tuberculosis, Mycobacterium bovis, and several nontuberculous mycobacteria by a broth dilution method. 5-Chloropyrazinamide was more active than pyrazinamide against all organisms tested. It is likely that this agent has a different mechanism of action than pyrazinamide.