Analysis of swirling flow in hydrocyclones operating under dense regime

There are many circumstances where hydrocyclone performance and dense flow are intertwined, such as for example when feed solids flow exceeds hydrocyclone capacity during continuous operations. The work reported here, which is part of an ongoing research effort to develop a robust CFD model for prediction of hydrocyclone performance, focuses on hydrocyclone operation under high solids concentration. The paper presents the basic physics framework that accounts for solid–liquid and solid–solid interactions under hydrocyclone’s swirling flow. Operating conditions that are past the transition from spray to rope regime are deliberately chosen for this purpose. Model predictions are validated by comparison with solids split and separation curves measured on a 100 mm diameter hydrocyclone. CFD model predictions permit taking an insightful look at the inside of a hydrocyclone under extreme operating conditions, which would be difficult to achieve experimentally. Velocity profiles, G-force distribution and distribution of solids predicted by CFD are bound to lead to a better understanding of the separation that takes place inside a hydrocyclone, which may eventually help improve hydrocyclone design and performance

Is the fish-hook effect in hydrocyclones a real phenomenon?

Although the fish-hook effect has been reported by many for a very long time, scientists and practitioners alike share contradictory opinions about this phenomenon. While some believe that it is of physical origin, others opine that it is the result of measurement errors. This article investigates the possibility that the fish-hook effect could indeed be measurement error related. Since all the experimental errors are embedded in the raw size distribution measurements, the paper first lays down the steps that lead to estimation of the partition function and confidence bounds, which are seldom reported in hydrocyclone literature, from the errors associated with the experimental size distribution measurements. Using several data sets generated using a 100 mm diameter hydrocyclone operating under controlled dilute to dense regimes, careful analysis of the partition functions following the developed methodology yields unambiguous evidence that the fish-hook effect is a real physical phenomenon. An attempt is also made to reunite some of the major contradictory views behind the existence of the fish-hook based on sound statistical arguments

Mechanistic modelling of water partitioning behaviour in hydrocyclone

A new mechanistic model on water split behaviour in a hydrocyclone has been developed based on the convoluted hydrodynamics of swirling flows in a confined environment. A comprehensive study has been accomplished on the genesis and subsequent distribution of G force based on the characterization of internal flow features of a 2 in hydrocyclone through computational fluid dynamics (CFD) approach. The difference between the magnitude of G force in cylindrical and spigot regions is taken into account as a new hydrodynamic parameter to compute the water split behaviour. Specifically, our analysis reveals a semi-empirical relationship between the water split with G force difference (ΔG), the vortex finder diameter (Dvf) and the spigot diameter (Dsp). The developed model is validated against experimental data and show good prediction accuracy. Unique aspect of the developed empirical model is that the underlying mechanism of incipient flow peculiarity is implicitly accounted to rummage the separation characteristics in a quantifiable manner. In addition to rationalize the flow split behaviour of hydrocyclones, this new hydrodynamic indicator seems promising to be used as a scale-up parameter in envisaging the separation performance for a given application

Performance monitoring of a hydrocyclone based on underflow discharge angle

The performance of a hydrocyclone as a separation device is never perfect and rigorous research efforts are still continuing along various directions towards achieving optimum solutions. The modus operandi of performance optimization is important for quick and non-invasive monitoring of hydrocyclone performance. Therefore, in the present study, an application potential of spray angle as a performance monitoring tool has been explored to investigate the operation state of a hydrocyclone. In this context, phenomenological features of spray discharge over a wide range of injection pressure and feed solid concentration have been investigated. The emphasis of the present study is to verse the amendment of the hydrocyclone operational state with the corresponding change in underflow discharge pattern. The pattern of the underflowdischarge profilewas captured using a digital camera and analyzed based on an image processing algorithm to detect the discharge angle under different operating and design conditions. Stability and reproducibility of the spray angle at fixed operating condition have also been confirmed. Subsequent analysis shows that the spray angle is sensitive to variations of operating and design variables. More specifically the effect of feed slurry concentration has been characterized and is of major importance for the transition to roping. On this basis, an attempt has also been made to develop an empirical correlation based on experimental data. The developed correlation shows that the discharge angle could possibly be used as a reliable tool to monitor hydrocyclone performance

Fructose-1, 6-bisphosphatase in human fetal brain and liver during development

Activity of fructose-1,6-bisphosphatase (EC 3.1.3.11), one of the key gluconeogenic enzymes, was measured in human fetal brain and liver during development. Fructose-1,6-bisphosphatase was distributed throughout the different regions of the brain. In contrast to the partially purified enzyme from the brain, the liver enzyme was dependent on Mg2+ for maximal activity, EDTA, citrate, oleate and linoleate were stimulatory, whereas 5'-AMP inhibited the activity of the liver enzyme

Diversification and evolution of L-myo-inositol 1-phosphate synthase11Dedicated to Dr. Frank Eisenberg, Jr., who introduced A.L.M. to this fascinating enzyme/protein.

AbstractL-myo-Inositol 1-phosphate synthase (MIPS, EC 5.5.1.4), the key enzyme in the inositol and phosphoinositide biosynthetic pathway, is present throughout evolutionarily diverse organisms and is considered an ancient protein/gene. Analysis by multiple sequence alignment, phylogenetic tree generation and comparison of newly determined crystal structures provides new insight into the origin and evolutionary relationships among the various MIPS proteins/genes. The evolution of the MIPS protein/gene among the prokaryotes seems more diverse and complex than amongst the eukaryotes. However, conservation of a ‘core catalytic structure’ among the MIPS proteins implies an essential function of the enzyme in cellular metabolism throughout the biological kingdom

An insight into the molecular basis of salt tolerance of L-myo-inositol 1-P synthase (PcINO1) from porteresia coarctata (Roxb.) tateoka, a halophytic wild rice1

The molecular basis of salt tolerance of L-myo-inositol 1-P synthase (MIPS; EC 5.5.1.4) from Porteresia coarctata (Roxb.) Tateoka (PcINO1, AF412340) earlier reported from this laboratory, has been analyzed by in vitro mutant and hybrid generation and subsequent biochemical and biophysical studies of the recombinant proteins. A 37-amino acid stretch between Trp-174 and Ser-210 has been confirmed as the salt-tolerance determinant domain in PcINO1 both by loss or gain of salt tolerance by either deletion or by addition to salt-sensitive MIPS(s) of Oryza (OsINO1) and Brassica juncea (BjINO1). This was further verified by growth analysis under salt environment of Schizosaccharomyces pombe transformed with the various gene constructs and studies on the differential behavior of mutant and wild proteins by Trp fluorescence, aggregation, and circular dichroism spectra in the presence of salt. 4,4'-Dianilino-1,1'-binaphthyl-5,5-disulfonic acid binding experiments revealed a lower hydrophobic surface on PcINO1 than OsINO1, contributed by this 37-amino acid stretch explaining the differential behavior of OsINO1 and PcINO1 both with respect to their enzymatic functions and thermodynamic stability in high salt environment. Detailed amino acid sequence comparison and modeling studies revealed the interposition of polar and charged residues and a well-connected hydrogen-bonding network formed by Ser and Thr in this stretch of PcINO1. On the contrary, hydrophobic residues clustered in two continuous stretches in the corresponding region of OsINO1 form a strong hydrophobic patch on the surface. It is conceivable that salt-tolerant MIPS proteins may be designed out of the salt-sensitive plant MIPS proteins by replacement of the corresponding amino acid stretch by the designated 37-amino acid stretch of PcINO1

Palatal implants are a good alternative to headgear: A randomized trial

Introduction: The objective of this study was to compare the effectiveness of midpalatal implants with that of headgear as methods of supplementing anchorage during orthodontic treatment. This was a randomized, clinical trial at the Chesterfield and North Derbyshire Royal Hospital NHS Trust and the Charles Clifford Dental Hospital, Sheffield, United Kingdom. Methods: Fifty-one orthodontic patients between the ages of 12 and 39 with absolute anchorage requirements were randomly allocated to receive either a midpalatal implant or headgear to reinforce orthodontic anchorage. The outcome measures of the trial were the surgical and orthodontic success rates of the implants, the number of visits, and the length of treatment time, and the success of treatment as judged by the peer assessment rating (PAR) score reductions and the patients’ attitudes to implant placement. Results: The surgical success rate of the implants was 75%, and the orthodontic success rate was more than 90%. Both implants and headgear proved to be effective methods of reinforcing anchorage. The total number of visits was greater in the implant group, but the overall treatment times were almost identical. There were no statistically significant differences between the 2 groups in PAR scores either at the start or the end of treatment, and the percentages of PAR score reductions were almost identical. The patients had no problems accepting midpalatal implants as a method of reinforcing anchorage. Conclusions: Midpalatal implants are an acceptable technique for reinforcing anchorage in orthodontic patients and a good alternative for patients who do not wish to wear headgear

The CMS Outer Hadron Calorimeter

The CMS hadron calorimeter is a sampling calorimeter with brass absorber and plastic scintillator tiles with wavelength shifting fibres for carrying the light to the readout device. The barrel hadron calorimeter is complemented with a outer calorimeter to ensure high energy shower containment in CMS and thus working as a tail catcher. Fabrication, testing and calibrations of the outer hadron calorimeter are carried out keeping in mind its importance in the energy measurement of jets in view of linearity and resolution. It will provide a net improvement in missing \et measurements at LHC energies. The outer hadron calorimeter has a very good signal to background ratio even for a minimum ionising particle and can hence be used in coincidence with the Resistive Plate Chambers of the CMS detector for the muon trigger

Measurements of branching fraction ratios and CP-asymmetries in suppressed B^- -> D(-> K^+ pi^-)K^- and B^- -> D(-> K^+ pi^-)pi^- decays

We report the first reconstruction in hadron collisions of the suppressed decays B^- -> D(-> K^+ pi^-)K^- and B^- -> D(-> K^+ pi^-)pi^-, sensitive to the CKM phase gamma, using data from 7 fb^-1 of integrated luminosity collected by the CDF II detector at the Tevatron collider. We reconstruct a signal for the B^- -> D(-> K^+ pi^-)K^- suppressed mode with a significance of 3.2 standard deviations, and measure the ratios of the suppressed to favored branching fractions R(K) = [22.0 \pm 8.6(stat)\pm 2.6(syst)]\times 10^-3, R^+(K) = [42.6\pm 13.7(stat)\pm 2.8(syst)]\times 10^-3, R^-(K)= [3.8\pm 10.3(stat)\pm 2.7(syst]\times 10^-3, as well as the direct CP-violating asymmetry A(K) = -0.82\pm 0.44(stat)\pm 0.09(syst) of this mode. Corresponding quantities for B^- -> D(-> K^+ pi^-)pi^- decay are also reported.Comment: 8 pages, 1 figure, accepted by Phys.Rev.D Rapid Communications for Publicatio