bluuebunny/crossref_metadata_2025 huggingface dataset:
Anaemia among adults in Kassala, Eastern Sudan
Authors: Abdallah Tajeldin M , Adam Ishag , Abdelhadi Mutaz A , Siddig Mohammed F , Ali AbdelAziem A
Published: April 2012

Background

The increased heterogeneity in the distribution of social and biological risk factors makes the epidemiology of anaemia a real challenge. A cross-sectional study was conducted at Kassala, Eastern Sudan during the period of January — March 2011 to investigate the prevalence and predictors of anaemia among adults (> 15 years old).

Findings

Out of 646, 234 (36.2%) adults had anaemia; 68 (10.5%); 129 (20.0%) and 37 (5.7%) had mild, moderate and severe anaemia, respectively. In logistic regression analyses, age (OR = 1.0, CI = 0.9–1, P = 0.7), rural vs. urban residency (OR = 0.9, CI = 0.7–1.3, P = 0.9), female vs. male gender (OR = 0.8, CI = 0.6–1.1, P = 0.3), educational level ≥ secondary level vs. < secondary level (OR = 1.0, CI = 0.6–1.6, P = 0.8) and Hudandawa vs. non-Hudandawa ethnicity (OR = 0.8, CI = 0.6–1, P = 0.1) were not associated with anaemia.

Conclusion

There was a high prevalence of anaemia in this setting, anaemia affected adults regardless to their age, sex and educational level. Therefore, anaemia is needed to be screened for routinely and supplements have to be employed in this setting.
Interactions of extracts from selected chewing stick sources with Aggregatibacter actinomycetemcomitans
Authors: Kwamin Francis , Gref Rolf , Haubek Dorte , Johansson Anders
Published: April 2012

Background

Aggregatibacter actinomycetemcomitans produces a leukotoxin that activates a pro-inflammatory death of human monocytes/macrophages. A specific clone of this bacterium (JP2) has a 530-base pair deletion in the leukotoxin promoter gene and significantly enhanced expression of leukotoxin. This specific clone of A. actinomycetemcomitans is common in some African populations and has a strong association with periodontal attachment loss in adolescents in these populations. Chewing sticks of plant origin are commonly used as oral hygiene tool in Africa, but their role as a therapeutic agent in periodontal disease is poorly investigated.

Results

Ethanol extracts were made from 7 common plants used as chewing sticks in West-Africa. None of the tested extracts inhibited growth of A. actinomycetemcomitans. However, extracts from Psidium guajava (Guava) completely neutralized the cell death and pro-inflammatory response of human leukocytes induced by the leukotoxin. None of the six other tested chewing stick extracts showed this effect.

Conclusions

The discovery that extracts from Guava efficiently neutralizes A. actinomycetemcomitans leukotoxicity might lead to novel therapeutic agents and strategies for prevention and treatment of aggressive forms of periodontitis induced by infections with the highly leukotoxic JP2 clone of this bacterium.
Differential Expression of RBM5, EGFR and KRAS mRNA and protein in non-small cell lung cancer tissues
Authors: Liang Hong , Zhang Jie , Shao Chen , Zhao Lijing , Xu Wei , Sutherland Leslie C , Wang Ke
Published: April 2012

Background

RNA binding motif 5 (RBM5) is a tumor suppressor gene that modulates apoptosis through the regulation of alternative splicing of apoptosis-related genes. This study aimed to detect RBM5 expression in non-small cell lung cancer (NSCLC) and to associate RBM5 expression with clinicopathological data from NSCLC patients and EGFR and KRAS expression to better understand the potential role of RBM5 in NSCLC.

Method

Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting were performed to detect expression of mRNA and protein, respectively, of RBM5, EGFR and KRAS in 120 paired non-tumor and tumor samples of NSCLC.

Results

The data showed that expression of RBM5 mRNA and protein was significantly reduced in NSCLC compared to normal tissues, whereas expression of both EGFR and KRAS genes was increased in NSCLC compared to normal tissues. Furthermore, the reduced RBM5 protein expression correlated with smoking status, tumor stage and lymph node metastasis of NSCLC, while overexpression of EGFR and KRAS proteins correlated with tumor stage and lymph node metastasis of NSCLC. Overexpression of KRAS protein was more frequent in smokers with NSCLC. In addition, expression of RBM5 mRNA and protein was negatively correlated with expression of EGFR and KRAS mRNA and protein in NSCLC tissues.

Conclusion

This study suggests further evaluation of RBM5 expression is warranted for use of RBM5 as a biomarker for NSCLC patients.
Short and long terms healing of the experimentally transverse sectioned tendon in rabbits
Authors: Oryan Ahmad , Moshiri Ali , Meimandi-Parizi Abdul-Hamid
Published: April 2012

Background

The incidences of tendon injuries in certain sections of human or animal populations such as athletes are high, but every human or animal, regardless of age or level of activity experiences some degree of tendon injury. In spite of the various investigations of injuries and treatment, comprehensive studies dealing with the histological, ultrastructural and biomechanical aspects of healing of load-bearing tendons are rare. This study was designed to compare the outcome of healing of the transverse sectioned superficial digital flexor tendon (SDFT) after 28 and 84 days post injury (DPI) in rabbits.

Methods

Forty white New Zealand mature female rabbits were randomly divided into two equal groups of 28 and 84 DPI After tenotomy and surgical repair of the left SDFT, the injured legs were casted for 14 days. The weight of the animals, tendon diameter, and clinical, radiographic and ultrasonographic evaluations were conducted at weekly intervals. The animals were euthanized on 28 and 84 DPI and the tendons were evaluated for histopathological, ultrastructural, biomechanical and percentage dry weight parameters.

Results

Although the clinical, ultrastructural, morphological and biomechanical properties of the injured tendons on day 84 showed a significant improvement compared to those of the 28 DPI, these parameters were still significantly inferior to their normal contra-lateral tendons.

Conclusions

This study showed that tendon healing is very slow and at 84 days post-injury the morphological and biomechanical parameters were still inferior to the normal tendons and many collagen fibrils still had the same diameter as those seen at 28 DPI.
Nocardia globerula NHB-2 nitrilase catalysed biotransformation of 4-cyanopyridine to isonicotinic acid
Authors: Sharma Nitya Nand , Sharma Monica , Bhalla Tek Chand
Published: April 2012

Isonicotinic acid (INA) is an important pyridine derivative used in the manufacture of isoniazid (antituberculosatic drug) and other pharmaceutically important drugs. Nitrilase catalysed processes for the synthesis of pharmaceutically important acids from their corresponding nitriles are promising alternative over the cumbersome, hazardous, and energy demanding chemical processes. Nitrilase of Nocardia globerula NHB-2 (NitNHB2) is expressed in presence of isobutyronitrile in the growth medium (1.0% glucose, 0.5% peptone, 0.3% beef extract, and 0.1 % yeast extract, pH 7.5). NitNHB2 hydrolyses 4-cyanopyridine (4-CP) to INA without accumulation of isonicotinamide, which is common in the reaction catalysed via fungal nitrilases. The NitNHB2 suffers from substrate inhibition effect and hydrolysing activity up to 250 mM 4-CP was recorded. Complete conversion of 200 mM 4-CP to INA was achieved in 40 min using resting cell concentration corresponding to 10 U mL-1 nitrilase activity in the reaction. Substrate inhibition effect in the fed batch reaction (200 mM substrate feed/40min) led to formation of only 729 mM INA. In a fed batch reaction (100 mM 4-CP/20min), substrate inhibition effect was encountered after 7th feed and a total of 958 mM INA was produced in 400 min. The fed batch reaction scaled up to 1 L and 100% hydrolysis of 700 mM of 4-CP to INA at 35°C achieved in 140 min. The rate of INA production was 21.1 g h-1 mgDCW
-1. This is the fastest biotransformation process ever reported for INA production with time and space productivity of 36 g L-1 h-1 using a bacterial nitrilase.
Reduction of low-density lipoprotein receptor-related protein (LRP1) in hippocampal neurons does not proportionately reduce, or otherwise alter, amyloid deposition in APPswe/PS1dE9 transgenic mice
Authors: Xu Guilian , Green Cameron C , Fromholt Susan E , Borchelt David R
Published: April 2012

Introduction

The low-density lipoprotein receptor-related protein (LRP1) and its family members have been implicated in the pathogenesis of Alzheimer's disease. Multiple susceptibility factors converge to metabolic pathways that involve LRP1, including modulation of the processing of amyloid precursor protein (APP) and the clearance of Aβ peptide.

Methods

We used the Cre-lox system to lower LRP1 levels in hippocampal neurons of mice that develop Alzheimer-type amyloid by crosses between mice that express Cre recombinase under the transcriptional control of the GFAP promoter, mice that harbor loxp sites in the LRP1 gene, and the APPswe/PS1dE9 transgenic model. We compared amyloid plaque numbers in APPswe/PS1dE9 mice lacking LRP1 expression in hippocampus (n = 13) to mice with normal levels of LRP1 (n = 12). Student t-test was used to test whether there were significant differences in plaque numbers and amyloid levels between the groups. A regression model was used to fit two regression lines for these groups, and to compare the rates of Aβ accumulation.

Results

Immunohistochemical analyses demonstrated efficient elimination of LRP1 expression in the CA fields and dentate gyrus of the hippocampus. Within hippocampus, we observed no effect on the severity of amyloid deposition, the rate of Aβ40/42 accumulation, or the architecture of amyloid plaques when LRP1 levels were reduced.

Conclusions

Expression of LRP1 by neurons in proximity to senile amyloid plaques does not appear to play a major role in modulating the formation of these proximal deposits or in the appearance of the associated neuritic pathology.
Statins accelerate the onset of collagen type II-induced arthritis in mice
Authors: Vandebriel Rob J , De Jong Hilda JI , Gremmer Eric R , Klungel Olaf H , Tervaert Jan-Willem Cohen , Slob Wout , Van Der Laan Jan Willem , Van Loveren Henk
Published: April 2012

Introduction

Statins (hydroxymethylglutaryl coenzyme A reductase inhibitors) are effective in reducing the risk of cardiovascular morbidity and mortality in patients with hyperlipidemia, hypertension, or type II diabetes. Next to their cholesterol-lowering activity, statins have immunomodulatory properties. Based on these properties, we hypothesized that statin use may eventually lead to dysregulation of immune responses, possibly resulting in autoimmunity. We have recently shown in an observational study that statin use was associated with an increased risk of developing rheumatoid arthritis. Our objective was to investigate whether a causal relationship could be established for this finding.

Methods

The mouse collagen type II (CII)-induced arthritis (CIA) model was used, with immunization, challenge, and euthanasia at days 0, 21, and 42, respectively. Statins were given orally before (day -28 until day 21) or after (day 21 until day 42) CIA induction. Atorvastatin (0.2 mg/day) or pravastatin (0.8 mg/day) was administered. Arthritis was recorded three times a week. Serum anti-CII autoantibodies and cytokines in supernatants from Concanavalin-A-stimulated lymph node cells and CII-stimulated spleen cells were measured.

Results

Statin administration accelerated arthritis onset and resulted in 100% arthritic animals, whereas only seven out of 12 nonstatin control animals developed arthritis. Atorvastatin administration after CIA induction resulted in earlier onset than atorvastatin administration before induction, or than pravastatin administration before or after induction. The arthritic score of animals given pravastatin before CIA induction was similar to that of the nonstatin controls, whereas the other groups that received statins showed higher arthritic scores. Atorvastatin administration, especially before CIA induction, increased anti-CII autoantibody production. IL-2 and IL-17 production by lymph node and spleen cells was higher in CIA animals than in PBS controls, but was not affected by statin administration. While IFNγ production was not affected by CIA induction, atorvastatin administration before CIA induction increased the production of this cytokine.

Conclusion

These data support previous results from our observational studies, indicating a role for statins in the induction of autoimmunity.
Enhanced RAD21 cohesin expression confers poor prognosis in BRCA2 and BRCAX, but not BRCA1 familial breast cancers
Authors: Yan Max , Xu Huiling , Waddell Nic , Shield-Artin Kristy , Haviv Izhak ,   kConFab authors, McKay Michael J , Fox Stephen B
Published: April 2012

Introduction

The RAD21 gene encodes a key component of the cohesin complex, which is essential for chromosome segregation, and together with BRCA1 and BRCA2, for high-fidelity DNA repair by homologous recombination. Although its expression correlates with early relapse and treatment resistance in sporadic breast cancers, it is unclear whether familial breast cancers behave in a similar manner.

Methods

We performed an immunohistochemical analysis of RAD21 expression in a cohort of 94 familial breast cancers (28 BRCA1, 27 BRCA2, and 39 BRCAX) and correlated these data with genotype and clinicopathologic parameters, including survival. In these cancers, we also correlated RAD21 expression with genomic expression profiling and gene copy-number changes and miRNAs predicted to target RAD21.

Results

No significant differences in nuclear RAD21 expression were observed between BRCA1 (12 (43%) of 28), BRCA2 (12 (44%) of 27), and BRCAX cancers (12 (33%) of 39 (p = 0.598). No correlation was found between RAD21 expression and grade, size, or lymph node, ER, or HER2 status (all P > 0.05). As for sporadic breast cancers, RAD21 expression correlated with shorter survival in grade 3 (P = 0.009) and but not in grade 1 (P = 0.065) or 2 cancers (P = 0.090). Expression of RAD21 correlated with poorer survival in patients treated with chemotherapy (P = 0.036) but not with hormonal therapy (P = 0.881). RAD21 expression correlated with shorter survival in BRCA2 (P = 0.006) and BRCAX (P = 0.008), but not BRCA1 cancers (P = 0.713). Changes in RAD21 mRNA were reflected by genomic changes in DNA copy number (P < 0.001) and by RAD21 protein expression, as assessed with immunohistochemistry (P = 0.047). High RAD21 expression was associated with genomic instability, as assessed by the total number of base pairs affected by genomic change (P = 0.048). Of 15 miRNAs predicted to target RAD21, mir-299-5p inversely correlated with RAD21 expression (P = 0.002).

Conclusions

Potential use of RAD21 as a predictive and prognostic marker in familial breast cancers is hence feasible and may therefore take into account the patient's BRCA1/2 mutation status.
Role of Ultrasonographic/Clinical Profile, Cytology, and BRAF V600E Mutation Evaluation in Thyroid Nodule Screening for Malignancy: A Prospective Study
Authors: Rossi Martina , Buratto Mattia , Bruni Stefania , Filieri Carlo , Tagliati Federico , Trasforini Giorgio , Rossi Roberta , Beccati Maria Donatella , degli Uberti Ettore C. , Zatelli Maria Chiara
Published: April 2012

Context:

Ultrasound (US)-guided fine-needle aspiration biopsy (FNAB) is the most reliable nonsurgical test for distinguishing benign from malignant thyroid nodules. However, there is no consensus on which nodules should undergo FNAB.

Aims:

The aims of this study were to evaluate the utility of US-guided FNAB in the diagnostic assessment of nodules with or without clinical/US features suggestive for malignancy and to investigate the additional contribution of BRAF V600E mutation analysis in the detection of differentiated thyroid cancer.

Design and Methods:

Thyroid cytoaspirates from 2421 nodules at least 4 mm in diameter were performed in 1856 patients who underwent cytological evaluation and biomolecular analysis.

Results:

Cytology showed high positive predictive value and specificity for the diagnosis of malignant lesions. BRAF V600E mutation was found in 115 samples, 80 of which were also cytologically diagnosed as papillary thyroid cancer. BRAF mutation analysis significantly enhanced the diagnostic value of cytology, increasing FNAB diagnostic sensitivity for malignant nodules by approximately 28%. Micro PTC (63% of diagnosed papillary thyroid carcinoma) showed a high prevalence of multifocality, extrathyroidal extension, and lymph node metastases, underlining the malignant potential of thyroid microcarcinomas. Each investigated US/clinical characteristic of suspected malignancy correlated with the presence of a thyroid cancer in thyroid nodules with diameter of at least 4 mm.

Conclusions:

These data indicate that nodules of at least 4 mm may underlie a thyroid cancer independently of US/clinical characteristics of suspected malignancy, suggesting the need to perform FNAB. The diagnostic sensitivity for thyroid cancer is significantly increased by BRAF V600E mutation analysis, indicating that the screening for BRAF mutation in FNAB samples has a relevant diagnostic potential.
Reduced mRNA and Protein Expression of Perilipin A and G0/G1 Switch Gene 2 (G0S2) in Human Adipose Tissue in Poorly Controlled Type 2 Diabetes
Authors: Nielsen Thomas S. , Kampmann Ulla , Nielsen Roni R. , Jessen Niels , Ørskov Lotte , Pedersen Steen B. , Jørgensen Jens O. , Lund Sten , Møller Niels
Published: April 2012

Context:

Increased lipolysis and free fatty acid (FFA) levels contribute significantly to the pathogenesis of chronic and acute insulin resistance in type 2 diabetes, but the underlying mechanisms are uncertain.

Objective:

Our objective was to test whether increased lipolysis and FFA levels induced by insulin withdrawal are accompanied by increased adipose tissue (AT) contents of adipose triglyceride lipase (ATGL) and/or altered intracellular ATGL regulation.

Design and Participants:

Nine patients with type 2 diabetes were examined twice in a randomized crossover design after 16 h of 1) hyperglycemia/insulin withdrawal and 2) euglycemia/insulin infusion. Blood samples were drawn and a sc abdominal AT biopsy was obtained.

Setting:

The study was conducted at a university hospital research unit.

Results:

Circulating glucose (7.2 ± 0.3 vs. 11.2 ± 0.8 mmol/liter) and FFA (0.51 ± 0.05 vs. 0.65 ± 0.04 mmol/liter) were increased and insulin levels decreased after insulin withdrawal. AT ATGL protein tended to be increased (P = 0.075) after insulin withdrawal; by contrast, AT protein and mRNA content of perilipin A (Plin) and G0/G1 switch gene 2 (G0S2), known negative regulators of ATGL activity, were decreased by 20–30% (all P values <0.03). All measured parameters related to hormone-sensitive lipase remained unaffected.

Conclusions:

We found reduced mRNA and protein content of Plin and G0S2 and borderline increased ATGL protein in sc AT from poorly controlled type 2 diabetic subjects. This suggests that increased ATGL activity may contribute to the elevated lipolysis and circulating FFA levels in acute insulin withdrawal and metabolic dysregulation in type 2 diabetic patients and that this mechanism may be modifiable.
Laminin is required to orient epithelial polarity in theC. eleganspharynx
Authors: Rasmussen Jeffrey P. , Reddy Sowmya Somashekar , Priess James R.
Published: April 2012

The development of many animal organs involves a mesenchymal to epithelial transition, in which cells develop and coordinate polarity through largely unknown mechanisms. The C. elegans pharynx, which is an epithelial tube in which cells polarize around a central lumen, provides a simple system with which to understand the coordination of epithelial polarity. We show that cell fate regulators cause pharyngeal precursor cells to group into a bilaterally symmetric, rectangular array of cells called the double plate. The double plate cells polarize with apical localization of the PAR-3 protein complex, then undergo apical constriction to form a cylindrical cyst. We show that laminin, but not other basement membrane components, orients the polarity of the double plate cells. Our results provide in vivo evidence that laminin has an early role in cell polarity that can be distinguished from its later role in basement membrane integrity.
Prp2-mediated protein rearrangements at the catalytic core of the spliceosome as revealed by dcFCCS
Authors: Ohrt Thomas , Prior Mira , Dannenberg Julia , Odenwälder Peter , Dybkov Olexandr , Rasche Nicolas , Schmitzová Jana , Gregor Ingo , Fabrizio Patrizia , Enderlein Jörg , Lührmann Reinhard
Published: April 2012

The compositional and conformational changes during catalytic activation of the spliceosome promoted by the DEAH box ATPase Prp2 are only poorly understood. Here, we show by dual-color fluorescence cross-correlation spectroscopy (dcFCCS) that the binding affinity of several proteins is significantly changed during the Prp2-mediated transition of precatalytic Bact spliceosomes to catalytically activated B* spliceosomes from Saccharomyces cerevisiae. During this step, several proteins, including the zinc-finger protein Cwc24, are quantitatively displaced from the B* complex. Consistent with this, we show that Cwc24 is required for step 1 but not for catalysis per se. The U2-associated SF3a and SF3b proteins Prp11 and Cus1 remain bound to the B* spliceosome under near-physiological conditions, but their binding is reduced at high salt. Conversely, high-affinity binding sites are created for Yju2 and Cwc25 during catalytic activation, consistent with their requirement for step 1 catalysis. Our results suggest high cooperativity of multiple Prp2-mediated structural rearrangements at the spliceosome's catalytic core. Moreover, dcFCCS represents a powerful tool ideally suited to study quantitatively spliceosomal protein dynamics in equilibrium.
Simulation and Optimization of an Auto-Thermal Ammonia Synthesis Reactor
Authors: Angira Rakesh
Published: April 2012

This paper deals with the simulation and optimization of an auto-thermal ammonia synthesis reactor. In the present study, three methods, viz., Eulers method, Runge-Kutta method (4th order with fixed step size) and NAG subroutine (D02EJF) in MATLAB, are used for simulation. A software package POYMATH is also used to solve three coupled model equations. The effect of top temperature on the optimal reactor length is discussed and results are compared with that reported in literature. Also, the Differential Evolution (DE) in combination with Runge-Kutta method is used for optimization, considering both reactor length and top temperature simultaneously as independent variables. The new results obtained for optimal reactor length and top temperature are presented.
Comparative Study of Numerical Simulations of the RESS Process: The Supercritical Pure Fluid Expansion
Authors: Hatem Ksibi
Published: April 2012

We present a review of numerical models and related (CFD) simulations for the so-called RESS process (rapid expansion of supercritical solutions), which has been attracted with so much attention in the literature for the potential applications related to the production of microparticulates of selected materials with controllable morphology and narrow-size distributions (using supercritical fluids, especially the carbon dioxide). The numerical computation of supercritical fluid flows in general is extremely challenging because of the complexity of the involved physical processes and the different space and time scales. The aim of this study is the focused analysis of advanced mathematical modeling of the supercritical fluid expansion in the RESS process with the specific intent of delineating a possible strategy for optimizing operating parameters. In particular, temperature, pressure, composition, flow rate and reactor dimensions are considered as variables potentially impacting the transport and growth of crystallized particles.
Adsorption and UV-Visible Light Induced Degradation of Methylene Blue over ZnO Nano-Particles
Authors: Islam Muhammad Amirul , Siddiquey Iqbal Ahmed , Rahman Khan Md. Azizur , Alam Md. Mahbubul , Islam Saiful S.M. , Hasnat Mohammad A.
Published: April 2012

Photocatalytic degradation of a heteropolyaromatic dye (methylene blue) in aqueous ZnO suspension was investigated under UV and visible light irradiation. Adsorption behavior was found to be well fitted with the Langmuir and Freundlich isotherms. Free energy of adsorption was found to be negative which indicates that adsorption was spontaneous. Under UV light irradiation for 6 hours, the catalytic process produced a net decolorization and mineralization (50 µM MB) of about 98% and 89% respectively. Meanwhile, under visible light irradiation (10 µM MB) for 8 hours these resulted ca. 95% and 77% decolorization and mineralization, respectively. Degradation efficiency was found to be highest at basic pH (8.6). Catalyst loading of 1.0 gl-1 was found to be optimum for the degradation of 100 µM MB solution. In all conditions the UV irradiation showed much better photo-assistance than the visible light irradiation.
Optimisation of C:N Ratio for Co-Digested Processed Industrial Food Waste and Sewage Sludge Using the BMP Test
Authors: Siddiqui Zuhaib , Horan N.J. , Anaman Kofi
Published: April 2012

Biomethane production from processed industrial food waste (IFW) in admixture with sewage sludge (primary and waste activated sludge: PS and WAS) was evaluated at a range of C:N ratios using a standard biochemical methane potential (BMP) test. IFW alone had a C:N of 30 whereas for WAS it was 5.4 and thus the C:N ratio of the blends fell in that range. Increasing the IFW content in mix improves the methane potential by increasing both the cumulative biogas production and the rate of methane production. Optimum methane yield 239 mL/g VSremoved occurred at a C:N ratio of 15 which was achieved with a blend containing 11 percent (w/w) IFW. As the fraction of IFW in the blend increased, volatile solids (VS) destruction was increased and this led to a reduction in methane yield and amount of production. The highest destruction of volatile solids of 93 percent was achieved at C:N of 20 followed by C:N 30 and 15. A shortened BMP test is adequate for evaluating optimum admixtures.
Use of Liquid Marbles as Micro-Reactors
Authors: Bormashenko Edward , Balter Revital , Aurbach Doron
Published: April 2012

Liquid marbles are droplets coated with hydrophobic micro-scaled powder. Micro-scaled particles of polyvinylidene fluoride formed highly permeable shell enwrapping 100 microliter droplet. This fact was used for converting liquid marbles into micro-reactors. Marbles containing the mixture of ammonia acetate, acetic acid and acetylacetone were exposed to formaldehyde vapor. Formaldehyde vapor absorbed by the liquid surface promoted the chemical reaction accompanied by marble coloring. Thus, mobile sliding and floating micro-reactors were produced. Liquid marbles can be used for remote sensing of gaseous organic contaminants.
On The Behavior of Partial Oxidation of Methane in a Pd-Membrane Reactor under Periodic Operation Conditions
Authors: Chibane Lemnouer , Djellouli Brahim
Published: April 2012

In the current study, a theoretical analysis of the behavior of the reaction of partial oxidation of methane performed in a palladium membrane reactor, operating under periodic conditions was carried out. The periodic operations in the pd-membrane reactor are supposed to be created by forcing some inputs cyclically using a sinusoidal function. The concerned inputs are the composition and mainly the steam and oxygen in the reactor inlet and the sweeping gas in the permeation side. It was found that the periodic operations applied to these inputs are beneficial since the predicted performance is improved. When the steam to methane ratio and the sweeping gas are running periodically both in phase, the conversion of methane and the pure hydrogen recovery can exceed the steady state levels and the H2/CO ratio is significantly reduced compared to the steady state operation.
Effects of Catalyst Precursor Type and Preparation Conditions, and Solvent Type on Activity and Selectivity of Pt/SiO2 Catalyst in Citral Hydrogenation
Authors: Depboylu Can O. , Yilmaz Selahattin , Akkurt Sedat
Published: April 2012

In this study, citral hydrogenation reaction in liquid phase over silica gel supported Pt catalysts was investigated. It was desired to hydrogenate carbonyl group selectively to produce valuable unsaturated alcohols, namely geraniol and nerol. Pt/SiO2 catalysts were prepared by impregnation method. The effects of parameters investigated in the present study included Pt precursor type (hexachloroplatinic acid (HCLPA), platinum II acetylacetonate (PAA)), catalyst activation temperature (350°C and 450°C), catalyst activation without calcination, catalyst washing with 0.1 M NaOH and solvent type (ethanol, 2-pentanol). The catalysts activities and selectivities were affected by the type of precursor and activation temperature. The maximum citral conversion (89.50 percent) was achieved at lower activation temperature (350°C) with PAA precursor based catalyst. It was observed that higher activation temperature provided lower citral conversion but higher selectivity to unsaturated alcohols; increasing the activation temperature to 450°C decreased citral conversion to 26.10 percent. But selectivity to unsaturated alcohols, geraniol and nerol, increased from 7.06 to 54.60 percent. Catalyst washing and 2-pentanol prevented acetal formation. Catalyst activation without calcination gave lower citral conversion (20.84 percent) and selectivity to unsaturated alcohols (30.00 percent).
Non Linear State and Parameters Estimation in Chemical Processes: Analysis and Improvement of Three Estimation Structures Applied to a CSTR
Authors: Botero Héctor , Álvarez Hernán
Published: April 2012

This paper proposes a new composite observer capable of estimating the states and unknown (or changing) parameters of a chemical process, using some input-output measurements, the phenomenological based model and other available knowledge about the process. The proposed composite observer contains a classic observer (CO) to estimate the state variables, an observer-based estimator (OBE) to obtain the actual values of the unknown or changing parameters needed to tune the CO, and an asymptotic observer (AO) to estimate the states needed as input to the OBE. The proposed structure was applied to a CSTR model with three state variables. With the proposed structure, the concentration of reactants and other CSTR parameters can be estimated on-line if the reactor and jacket temperatures are known. The procedure for the design of the proposed structure is simple and guarantees observer convergence. In addition, the convergence speed of state and parameter estimation can be adjusted independently.
Dynamic Technique to Determine Hexadecane Transfer Rate from Organic Phase to Aqueous Phase in a Three-Phase Bioreactor
Authors: Lizardi-Jiménez Manuel Alejandro , Saucedo-Castañeda Gerardo , Thalasso Frederic , Gutiérrez-Rojas Mariano
Published: April 2012

Determination of mass transfer of non-water soluble substrates, as hexadecane (HXD), is an important constraint in three-phase airlift bioreactor. A new simple dynamic technique able to measure the hexadecane transfer rate (HTR) in a three-phase airlift bioreactor (ALB) was studied in this work. The image analyses technique allowed measuring the resulting specific mass transfer area (aHXD). Gas chromatography was used to measure time-dependent transferred HXD and therefore the HXD transfer coefficient (kLHXD). Finally, HTR was calculated by using the equation HTR = kLaHXD(CHXD* - CHXD) where CHXD* and CHXD are the saturation HXD-aqueous interphase and HXD aqueous phase concentration, respectively. As case study, we successfully applied to the measurement of HTR during a typical ALB microbial consortium culture; values from 0.010 to 0.042 mg HXD (L h)-1 were found. This technique could be used to compare similar simultaneously occurring parameters to assess mass transfer constraints in three-phase systems.
Solid to Gas Temperature Gradient in a Microwave Fluidized Bed
Authors: Pajkic Zeljko , Schmidt Achim , Gerdes Thorsten , Willert-Porada Monika
Published: April 2012

Convective heat transfer from solid to gas was investigated in a microwave heated fluidized bed and compared to an identical conventionally heated bed. Fluidizing gas was fed at room temperature and heated in contact with the bed solid phase. Solid phase temperature was varied in range of 300-600°C. Temperature difference of the two phases and heat loss by gas stream were measured in both heating types and discussed regarding chemical reaction engineering and energy efficiency. Advantages of microwave heating in such systems were elaborated with an outlook to perspective applications of the process in field of materials science and engineering.
Non-Newtonian Flow Behavior on Frictional Pressure in Packed Bed
Authors: Patel Suresh Kumar , Majumder Subrata Kumar
Published: April 2012

The packed bed columns with non-Newtonian liquid are increasing importance as a simple and inexpensive means of achieving yield of different chemical and biochemical processes though their hydrodynamic behavior is complex and not yet fully understood. In this article non-Newtonian flow behavior on frictional pressure was investigated in packed bed within a range of liquid velocity 0.004-0.04 m/s. The frictional pressure loss in non-Newtonian liquid system has been analyzed by modified Ergun equation. The modification of the Ergun equation is incorporated with the flow behavior index of non-Newtonian liquid. The degree of frictional pressure loss decreases with increase in flow behavior index. A correlation has been developed to interpret the degree of effect on the frictional pressure loss. The correlation may be useful for further understanding and scale-up of the packed bed column for its industrial application.
MHD Free Convective Heat and Mass Transfer of a Chemically-Reacting Fluid from Radiate Stretching Surface Embedded in a Saturated Porous Medium
Authors: Rashad A.M. , M. Abdou M. Modather , Chamkha Ali
Published: April 2012

Magneto-hydrodynamic free convective heat and mass transfer of a viscous, incompressible, electrically conducting and chemically-reacting fluid adjacent to a vertical stretching sheet embedded in a saturated porous medium in the presence of a thermal radiation effect are investigated. The sheet is linearly stretched with uniform constant of temperature and concentration. The governing partial differential equations are transferred into a system of ordinary differential equations, which are solved numerically using a fourth order Runge-Kutta scheme with the shooting method. The effects of various parameters entering into the problem have been examined on the velocity and temperature profiles as well as the skin-friction coefficient, and Nusselt and Sherwood numbers are presented graphically and in tabular form.
Design Optimization of an LPG Thermal Cracker for Multiple Objectives
Authors: Nabavi Reza , Rangaiah G. P. , Niaei Aligholi , Salari Darioush
Published: April 2012

Ethylene and propylene, building blocks of the petrochemical industries, are mostly produced by steam cracking of hydrocarbons. In our recent work (Nabavi, Rangaiah, Niaei and Salari, Multiobjective Optimization of an Industrial LPG Thermal Cracker using a First Principles Model, Ind. Eng. Chem. Res. 2009, 48, 9523-9533), operation of an industrial liquefied petroleum gas (LPG) cracker was optimized for several sets of two and three objectives. In this work, optimization of an LPG cracker design is investigated for multiple objectives. The objectives considered are maximization of annual ethylene and propylene production, selectivity and run length, and minimization of severity and total heat duty per year. The elitist non-dominated sorting genetic algorithm adapted with the jumping gene operator, NSGA-II-aJG is used to solve the multi-objective optimization problems. The results of design optimization for multiple objectives are compared with those for operation optimization.
Fermentation of Groundnut Shell Enzymatic Hydrolysate for Fuel Ethanol Production by Free and Sorghum Stalks Immobilized Cells of Pichia stipitis NCIM 3498
Authors: Gajula Chandrasekhar , Chandel Anuj Kumar , Konakalla Radhika , Rudravaram Ravinder , Pogaku Ravindra , Mangamoori Lakshmi Narasu
Published: April 2012

Groundnut shell (GS), after separation of pod, is readily available as a potential feedstock for production of fermentable sugars. The substrate was delignified with sodium sulfite. The delignified substrate released 670 mg/g of sugars after enzymatic hydrolysis (50°C, 120 rpm, 50 hrs) using commercial cellulases (Dyadic® Xylanase PLUS, Dyadic Inc. USA). The groundnut shell enzymatic hydrolysate (45.6 g/L reducing sugars) was fermented for ethanol production with free and sorghum stalks immobilized cells of Pichia stipitis NCIM 3498 under submerged cultivation conditions. Immobilization of yeast cells on sorghum stalks were confirmed by scanning electron microscopy (SEM). A maximum of ethanol production (17.83 g/L, yield 0.44 g/g and 20.45 g/L, yield 0.47 g/g) was observed with free and immobilized cells of P. stipitis respectively in batch fermentation conditions. Recycling of immobilized cells showed a stable ethanol production (20.45 g/L, yield 0.47 g/g) up to 5 batches followed by a gradual downfall in subsequent cycles.
Numerical Investigation of Radiation Effects in Monolithic Catalytic Combustion Reactors
Authors: Mazumder Sandip , Grimm Michael
Published: April 2012

In modeling catalytic combustion in a monolithic catalytic converter, it is generally assumed that the gas within the individual monolith channels does not interfere with thermal radiation. To date, no quantitative study has been undertaken to validate this assumption. Past studies for carbon monoxide combustion also appear to indicate that the emissivity of the washcoat has little effect on the thermal radiation field. In order to investigate these two issues, methane-air combustion on platinum is modeled inside a single channel of a monolith using a detailed surface reaction mechanism comprised of 24 reactions between 19 species. Radiation transport is modeled using the Discrete Ordinates Method and a gray formulation. Planck-mean absorption coefficients of the gases, calculated from the HITEMP and HITRAN databases, are used to investigate participating medium effects. All calculations were performed using the commercial CFD code, CFD-ACE+, supplemented by user-subroutines for calculating the radiative properties of the gas mixture. Results show that the conversion percentages and temperature distributions are unaltered by the inclusion of participating medium radiation effects, verifying the commonly held belief, stated earlier. However, in strong contrast with carbon monoxide combustion, the emissivity of the washcoat was found to significantly affect flammability limits in the case of methane combustionthe flame being hotter and more stable for smaller values of emissivity.
CFD Modeling and Simulation of a Catalytic Micro-Monolith
Authors: Di Benedetto Almerinda , Di Sarli Valeria
Published: April 2012

In this work, a first step in modeling and simulating the thermal behavior of an entire catalytic micro-monolith was performed. In particular, a Computational Fluid Dynamics (CFD) model was developed for simulating three-channel and five-channel micro-combustors. For both configurations, the operating maps were built as functions of the inlet gas velocity and compared to the operating map of a single-channel configuration.Results show that, due to the relevance of heat losses in micro-devices, it is not possible to extrapolate the behavior of the multi-channel configurations from that of the single channel. Therefore, simulation of the entire catalytic micro-monolith is needed. However, this is computationally demanding: it has been found that the CPU time almost linearly increases with the number of channels simulated.Finally, for a fixed total mass flow rate, it has been demonstrated the opportunity to maximize the overall fuel conversion by means of a non-uniform distribution of mass flow rates among the channels.
Dye Decolorization by Immobilized Laccase: Statistical Optimization and Effect of Impeller Geometry
Authors: Ismail Nur Atiqah , M. Annuar M. Suffian , Ibrahim Shaliza
Published: April 2012

Laccase enzyme from Trametes versicolor was immobilized using calcium-alginate entrapment method to decolorize triphenylmethane dye. Selected variables namely initial dye concentration (ppm), agitation speed (rpm) and process time (day) were optimized using response surface methodology (RSM) Box-Behnken design protocol. Under optimal conditions, good percentage of crystal violet decolorization was observed. Experiments were scaled up to a one litre (1 L) stirred tank reactor (STR) to examine the effects of impeller speed and geometry. In both the shake flask and stirred vessel study, lower initial dye concentration showed greater removal of dye. The dye removal achieved in the stirred tank ranged from 14 percent to 36 percent. A 6-blade mixed flow impeller (6MFD) showed better removal than a radial 6-curved blade (6CB) impeller, at the same agitation speeds, albeit with higher power demand. The effect of impeller speed depended on level of dye concentration and impeller type; speed was important at low concentration for the 6MFD while the exact opposite was true for the 6CB.
Molecular Dynamics Simulation of Water and Ions in Nanopores of Lysozyme Protein Crystal
Authors: Farhadian Nafiseh , Shariaty-niassar Mojtaba , Malek Kourosh , Maghari Ali
Published: April 2012

Highly porous cross-linked protein crystals are a novel class of nanoporous materials with vast applications in biocatalysis and selective separation membranes. Long time equilibrium molecular dynamics (MD) simulations were performed to study the behavior of water and ions in the nanopores of lysozyme protein crystals. Pore size profile along different axes showed that the main pores lie along the z-axis consisting of an anisotropic structure. The morphology of pore network and pore sizes, influence water dynamics in protein crystals. Transport properties of water molecules were investigated under two diffusion regimes around protein surface, i.e. surface and core zone. Results showed that water molecules near the surface zone had the anomalous diffusion behavior while the behavior in the core zone was diffusive. Moreover, an anisotropic diffusion behavior was occurred along different axes in accordance to experimental predictions. Simulations demonstrated that nearly 16 percent of water molecules have the residence time above 100 ps at the first hydration layer around the protein crystal, while 3.3 percent of those remain in the cavities over a longer time of about 1400 ps. The behavior of chloride counter ions in the first hydration layer around the protein crystal or on the specific residues of the crystal was investigated as well. The simulation results were in a good agreement with the previous theoretical studies and experimental data. This study provides valuable insights into understanding the transport phenomena in the protein crystals in view of the nature of solvent-protein and ion-protein interactions.
Validation of CFD Model for Polysilicon Deposition and Production of Silicon Fines in a Silane Deposition FBR
Authors: Parker James M.
Published: April 2012

In this work, a CFD model for simulating industrial scale particle-fluid systems is used to model a fluidized bed reactor for the deposition of high-purity silicon from silane gas. The performance of these reactors is directly dependent on a large number of factors and parameters which make the design and optimization of the deposition reactors an engineering challenge. Using the reactor design and experimental data from work performed at the Jet Propulsion Laboratory as a basis for validation, the CFD model was found to accurately model the deposition rate, silicon fines production, and temperature distribution within a silane deposition reactor. Additionally, the CFD model is demonstrated to be an effective tool for comparing different reactor designs on the basis of fluidization mode, reaction conversion, heat transfer, and particle mixing.
Tank Car Conversion to a Reactor
Authors: Schruben Dale L. , Garcia Jaime
Published: April 2012

Tank car conversion into a reactor is undertaken herein for some large scale industrial processes of solids reacting with liquids to yield liquid products. The model loads liquid directly to the tank car, using it as the reactor as well. Savings accrue over the usual unit operation where the solids in the tank car are off-loaded to a reactor, then liquid is added to the reactor for solid conversion into a liquid product before reloading product to the tank car for customer delivery. Several analytical tools are used together to yield a sound picture of fluid flow in the tank car and its bed mass profile during the progress of bed reaction. This provides a basis for business and plant operation decisions.
Synthesis of Biodiesel Using Castor Oil under Microwave Radiation
Authors: Yuan Hong , Yang Bolun , Zhang Hailiang , Zhou Xiaowei
Published: April 2012

The castor oil was adopted to synthesize biodiesel (Fatty Acid Methyl Ester, FAME) under microwave radiation. Acid catalysts (NaHSO4H2O and AlCl3) and heterogeneous base catalyst (Na2CO3) were evaluated in the present study. The amounts of FAME in the product were analyzed by high performance liquid chromatography (HPLC). Experimental results show that the microwave radiation was an efficient method to enhance the reaction process. When the transesterification was carried out at 338 K, with 18:1 molar ratio of methanol to castor oil, 7.5wt% mass ratio of catalyst to castor oil, 200w microwave radiation power and 120 minutes reaction time, yields of 74, 73, 90% were obtained respectively using catalysts of NaHSO4H2O, AlCl3 and Na2CO3. The energy consumed by microwave heating and conventional heating in transesterification were measured, and the results showed that the microwave heating consumed less energy than the conventional heating to achieve the same amount of FAME.
Adsorption Thermodynamics of Toxin (65 kDa) and Protoxin (130 kDa) from Bacillus thuringiensis by Several Minerals
Authors: Zhou Xueyong , Liu Ning , Gao Jianbao , Zhang Mei , Cao Fei
Published: April 2012

The adsorption thermodynamics of toxin (65 kDa) and protoxin (130 kDa) from Bacillus thuringiensis (Bt) by several minerals (montmorillonite, kaolinite and silica) were investigated. The adsorption of toxin and protoxin by minerals was a spontaneous process in the range of temperature from 278K to 318K. The ?G0ads values of the toxin adsorption by above minerals ranged from -35.30 to -43.81 kJ mol-1, and the protoxin adsorption ranged from -35.87 to -44.83 kJ mol-1. The adsorption isotherms of both proteins followed Langmuir equation and the maximum adsorbed amount (Nadsmax) of protoxin were lower than those of toxin. The adsorption of Bt proteins on minerals was exothermic process, companying a negative value of ?H0ads. The ?H0ads values of the adsorption of toxin were between -3.85 and -4.98 kJ mol-1 and the protoxin were between -2.60 and -4.53 kJ mol-1. The standard adsorption entropy changes (?S0ads) of toxin ranged from 110.73 to 122.16 J mol-1 K-1, and of protoxin ranged from 122.57 to 132.77 J mol-1 K-1. The positive standard entropy (?S0ads) indicated that the freedom increased when the insecticidal proteins from B. thuringiensis adsorbed minerals. The Kads, ?G0ads and ?S0ads of toxin in value were lower than those of protoxin, suggesting that the spontaneous trend and the affinity between protoxin and minerals were larger than those of toxin.