bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and properties of highly branched Jatropha curcas L. oil derivatives
Authors: Daniel Louis , Ardiyanti Agnes R. , Schuur Boelo , Manurung Robert , Broekhuis Antonius A. , Heeres Hero J. 
Published: November 2010

AbstractThe synthesis and properties of a number of novel branched Jatropha curcas L. oil (JO) derivatives containing vicinal di‐ester units in the fatty acid chains are reported. Both the length (acetyl vs. hexanoyl) and the stereochemistry of the vicinal di‐ester units (cis vs. trans) were varied. The compounds were prepared by two different synthetic approaches using catalytic chemistry. The first approach involves epoxidation of JO using a Sharpless epoxidation with methyltrioxorhenium as the catalyst to give epoxidized JO (1), followed by an esterification reaction with the corresponding anhydrides using ammonium‐12‐molybdophosphate (AMP) as catalyst to give trans‐di‐esters of JO (4a, 4b). The second approach is based on the dihydroxylation of JO using either the Prilezhaev method, resulting in trans‐diols of JO (2), or the Upjohn method using osmium tetroxide as catalyst to give cis‐diols of JO (3). In subsequent steps, the diols were esterified with acetic‐ or hexanoic anhydride using dimethylaminopyridine as catalyst to produce the corresponding cis‐ and trans‐di‐esters of JO (5a, 5b, 6). The best cold flow properties (lowest pour‐ and cloud point, crystallization and melting temperature) were obtained for JO with hexanoyl branches in a trans orientation (5b, pour point of −14°C, melting point of −5°C, and crystallization temperature of −25°C) and these values are considerably better than for the JO source.Practical applications: Jatropha curcas L. oil (JO) is a toxic oil with potential applications not only as a green biodiesel but also as a feedstock for the oleochemical industry. The toxicity prohibits the use in food products but does not interfere with technical applications. Here we report studies on the synthesis of interesting JO derivatives (epoxidized, dihydroxylated, and branched compounds) that could be useful starting materials for a range of derivatives with a broad application perspective. The branched JO derivatives with vicinal di‐ester units in the fatty acid chains have cold flow properties (pour‐ and cloud point, melting point and crystallization temperature) considerably better than the original JO. In addition, the oxidative stability was also improved significantly. These novel branched JO derivatives may have interesting applications as cold‐flow improvers for biodiesel or as biolubricants.
Batch‐mode microfluidic radiosynthesis of N‐succinimidyl‐4‐[18F]fluorobenzoate for protein labelling
Authors: Bejot Romain , Elizarov Arkadij M. , Ball Ed , Zhang Jianzhong , Miraghaie Reza , Kolb Hartmuth C. , Gouverneur Véronique 
Published: November 2010

AbstractThe batch microfluidic technology is a promising system for sequential chemical steps combining the advantages of micro‐scale reactions, while addressing some shortcomings of flow‐through systems. We report herein the convenient three‐step, one‐pot synthesis and purification of [18F]SFB. [18F]SFB is a radiolabelling agent that can be used to label sensitive biomolecules, which are not accessible by direct nucleophilic 18F‐fluorination.Five sequential steps were performed with a batch microfluidic device to obtain the short‐lived positron‐emitter‐labelled molecule. Aqueous [18F]fluoride was concentrated and further eluted to a microreactor for evaporation. Nucleophilic 18F‐fluorination of the precursor was carried out at high temperature, prior to hydrolysis and subsequent activation of the 4‐[18F]fluorobenzoyl group. Purification on miniaturized solid‐phase finally afforded [18F]SFB in 25 min and 55±6% yield (not decay‐corrected) and >98% radiochemical purity. In this study, microfluidic prepared [18F]SFB could be further successfully used for labelling the epidermal growth factor protein.These results illustrate how microfluidic batch devices are advantageous for producing radiotracers for molecular imaging, e.g. Positron emission tomography. The technology offers many benefits such as the possibility to use much smaller quantities of starting material, reduced reaction time combined with improved efficiency, and easier purification. Copyright © 2010 John Wiley & Sons, Ltd.
Scale growth process at 1473 K on unmodified and yttrium‐ or chromium‐implanted β‐NiAl
Authors: Jedlinski J. , Grosseau‐Poussard J.‐L. , Bonnet G. , Kowalski K. , Bernasik A. , Smola G. , Nocun M. 
Published: November 2010

AbstractEarly oxidation of unmodified and yttrium‐implanted or chromium‐implanted β‐NiAl intermetallic compound at 1473 K was studied using a combination of two‐stage‐oxidation exposure with 18O2 as a tracer, SIMS elemental distribution analysis (depth profiling and imaging modes) and photoluminescence spectroscopy analysis of the scale phase composition.It was found that phase transformation of transient aluminium oxides, represented by θ‐ Al2O3 into stable and protective α‐Al2O3 occurs locally and is affected by implanted additions: Yttrium retarded while chromium appeared to accelerate it. Typical patch‐ and/or web‐like scale morphology of the growing scales was observed.
Teacher career paths, teacher quality, and persistence in the classroom: Are public schools keeping their best?
Authors: Goldhaber Dan , Gross Betheny , Player Daniel 
Published: November 2010

AbstractIn this paper we examine the mobility of early‐career teachers of varying quality, measured using value‐added estimates of teacher performance. Unlike previous studies that have examined these issues, we focus on the variation in these effects across the effectiveness distribution. We find that, on average, more effective teachers tend to stay in their initial schools and in the teaching profession. But there also appears to be heterogeneity in mobility behavior across the performance distribution and evidence that teacher mobility is affected by student demographics and achievement levels. © 2010 by the Association for Public Policy Analysis and Management.
Microwave‐assisted acid extraction methodology for trace elements determination in mastic gum of Pistacia lentiscus using inductively coupled plasma atomic emission spectrometry
Authors: Zachariadis George A. , Spanou Eleni A. 
Published: November 2010

AbstractIntroduction – To ensure food safety, accurate knowledge of the levels of several trace elements is necessary. This is also true for natural products of plants and resins used for human consumption or therapeutic treatment, like the mastic gum of Pistacia lentiscus. The rapid analysis of gum and resin matrices is a challenge because there are problems with the decomposition of such complicated matrices.Objective – To develop an efficient multielemental analytical method for the determination of trace elements and to compare different procedures for analyte extraction when microwave‐assisted digestion is applied.Methodology – The inductively coupled plasma atomic emission spectrometric (ICP‐AES) technique was applied and the optimum ICP conditions like radiofrequency power, argon flow rate and nebuliser sample uptake flowrate were found. The microwave‐assisted procedure was compared with that with conventional heating. Since mastic and resinous materials are difficult for dissolution and extraction of trace element, influential acid mixtures containing hydrofluoric acid proved to be capable of quantitative extraction of the analytes.Results – The digestion of mastic resin or similar matrices is significantly facilitated by using microwave radiation instead of conventional heating since the obtained recovery for several analytes is much higher. It was proved that the acid mixture of HCl–HNO3–HF was the most efficient for complete sample digestion and recovery of the analytes.Conclusions The performance characteristics of the developed method were evaluated against certified reference material and the method was proved reliable and applicable to the analysis of mastic gum and possibly to similar resinous matrices. Copyright © 2010 John Wiley & Sons, Ltd.
Simultaneous determination of naphthalene and anthraquinone derivatives in Rumex nepalensis Spreng. Roots by HPLC: comparison of different extraction methods and validation
Authors: Gautam Raju , Srivastava Amit , Jachak Sanjay M. 
Published: November 2010

AbstractIntroduction – Rumex nepalensis contains mainly anthraquinone and naphthalene derivatives. Although HPLC methods have been reported for the analysis of anthraquinones, neither a phytochemical analysis of Rumex species nor the simultaneous determination of anthraquinone and naphthalene derivatives in other samples has been reported so far.Objective – To develop and validate a HPLC method for the simultaneous determination of anthraquinone and naphthalene derivatives in R. nepalensis roots.Methodology – Anthraquinones and naphthalenes were extracted from R. nepalensis roots by three methods (reflux, ultrasonication and pressurized liquid extraction) using methanol. Separation was achieved on an RP C18 column with a gradient mobile phase consisting of 0.05% orthophosphoric acid in water (solvent A) and methanol (solvent B) using a UV detector (254 nm).Results – Small differences were observed in the contents of anthraquinone and naphthalene derivatives extracted by the three methods. Chrysophanol‐8‐O‐β‐D‐glucopyranoside and nepodin were detected as major constituents. The method showed a good linearity (r2 > 0.9992), high precision (RSD < 5%) and a good recovery (97–105%) of the compounds. The lowest detection limit was found to be 0.97 ng and the method was found to be robust.Conclusion – Reflux and ultrasonication were found to be the best suited methods for the extraction of glycosides and aglycones, respectively. The developed and validated HPLC method is simple, precise and accurate; and can hence be recommended as the method of choice for the analysis of anthraquinones and naphthalenes in R. nepalensis and other Rumex species for both quality control as well as routine analytical purposes. Copyright © 2010 John Wiley & Sons, Ltd.
Modelling of Pressure Distribution inside the SEN in a Stopper‐rod controlled System
Authors: Savolainen J. , Rousu A. , Fabritius T. , Mattila O. , Sulasalmi P. 
Published: November 2010

AbstractShrouding tubes and submerged entry nozzles (SEN) are mainly used on steel transfer between process units of continuous casters. Molten steel flow in the SEN or shrouding tube causes a pressure drop which creates possibilities for air aspiration through refractory material. The objective of this research was to model the pressure distribution in the SEN of a continuous caster using a full scale water model. Effects of casting speed, SEN immersion depth and liquid level of tundish on the pressures at the SEN wall and centre were defined. The experiments proved that SEN immersion depth had the most remarkable effect on the pressure inside the SEN. However experiments did not show a significant effect of casting speed and tundish liquid level on the pressure inside the SEN. This research presents a simplified model for pressure distribution in SEN. The presented model agrees well with measurements at the SEN wall.
Three‐dimensional Simulation of Thermosolutal Convection and Macrosegregation in Steel Ingots
Authors: Li W. S. , Shen H. F. , Liu B. C. 
Published: November 2010

AbstractThermosolutal convection and macrosegregation formation during the solidification of steel ingots are numerically simulated in three dimensions. The simulation is based on a fully coupled model for mass, momentum, energy, and species conservation equations. The interdendritic flow in the mushy zone is governed by Darcy's law, and the permeability term is discretized using an interpolated liquid fraction method. The numerical results for a benchmark test of macrosegregation in a Pb‐Sn alloy are compared with experimental data taken from the literature. The present model is applied to simulate the solidification of industrial steel ingots. Preliminary predictions are obtained, including the positive segregation in the hot top, and the conically shaped negative segregation zone at the bottom of the ingot. The predicted variation of the segregation ratio in carbon along the vertical centreline of an ingot is compared with measurements, and generally good agreement is observed. Future attention should be paid to the precision of prediction by considering complex solidification issues, such as the sedimentation of free equiaxed grains and the formation of shrinkage cavity.
Effects of TiN and AlN Nanoparticles in Hot Deformation of Austenite in Steels
Authors: Medina S.F. , Gómez M. , Valles P. 
Published: November 2010

AbstractRecrystallisation kinetics of two low‐carbon steels, of which one with Ti and the other with Al as precipitate‐forming elements was studied by means of hot torsion tests. The mean size of TiN and AlN particles that precipitate during hot deformation was analysed by transmission electron microscopy (TEM). These results, along with the determination of the activation energy, the precipitated volume fraction and the diffusion coefficients of Ti, Al and N in austenite explain the ineffectiveness of these particles to inhibit the static recrystallisation.
Numerical Cooling Strategy Design for Hot Rolled Dual Phase Steel
Authors: Suwanpinij P. , Togobytska N. , Prahl U. , Weiss W. , Hömberg D. , Bleck W. 
Published: November 2010

AbstractIn this article, a Mo‐Mn dual phase steel and its process parameters in hot rolling are discussed. The process window was derived by combining the experimental work in a hot deformation dilatometer and numerical calculation of the process parameters using rate law models for ferrite and martensite transformation. The ferrite formation model is based on the Leblond and Devaux approach while martensite formation is based on the Koistinen‐Marburger (K‐M) formula. The carbon enrichment during ferrite formation is taken into account for the following martensite formation. After completing the parameter identification for the rate law model, the evolution of phases in this steel can be addressed. Particularly, the simulations allow the prediction of preferable degree of retained strain and holding temperature on the run out table (ROT) for the required ferrite fraction.
Computational Modelling of Oxide Surface Tensions in Secondary Metallurgy and Continuous Casting
Authors: Heikkinen E.‐P. , Riipi J. , Fabritius T. , Pajarre R. , Koukkari P. 
Published: November 2010

AbstractTwo computational models were used to estimate the surface tensions of oxide systems containing SiO2, CaO, Na2O and Al2O3 as a function of temperature and composition. The compositions of the oxide melts were chosen to correspond to those of ladle slags in secondary metallurgy and to casting powders in continuous casting of steel. The first model uses Butler's equation to calculate the surface tensions of the multicomponent melts and is based on Tanaka et al.'s consideration of the ionic radii of the components as well as surface tensions and molar volumes of pure components. In the second model the same ionic radii dependent contribution is applied as activity coefficients to a constrained free energy model where the surface layer is considered as a separate phase in the system. In the model, the constrained interfacial area is analogous with a component mass balance in a traditional computation of a multiphase chemical equilibrium and surface energy with the corresponding chemical potential. Based on the results it is concluded that the effect of temperature on the surface tensions of the considered oxide melts is insignificant when compared to the effect of chemical composition. According to the validation the results agree well with published surface tension data. The multi‐component surface tension approach provides a practical method for evaluation of e.g. functioning of various casting powders in industrial steel casting practice.
Calculation of Oxygen and Sulfur Average Velocity on the Iron Surface: A Two‐dimensional Gas Model Study
Authors: Cao W. , Delin A. , Seetharaman S. 
Published: November 2010

AbstractIn the present work, a two‐dimensional (2D) gas model is derived and used to simulate the average velocity of individual atoms of the surface active elements oxygen and sulfur on the Fe(100) surface. The average velocity of oxygen and sulfur atoms was found to be related to the vibration frequencies and minimal energy barrier. The calculated results are based on data from density functional calculations combined with thermodynamics and statistical physics. The calculated average velocity of oxygen on the Fe (100) is lower than that of sulphur. This is because of the stronger interaction between oxygen and the first iron layer. We conclude that our simple 2D gas model may be useful for simulating and understanding the complex interfacial phenomena in the steelmaking refining process from an atomic point of view.
The Influence of Carbonaceous Material on the Melting Behaviour of Mould Powder
Authors: Singh D. , Bhardwaj P. , Yang Y. D. , McLean A. , Hasegawa M. , Iwase M. 
Published: November 2010

AbstractThe melting behaviour of mould powder during continuous casting is an important consideration with respect to caster performance, production rate and steel quality. In this experimental study the effect of different carbonaceous materials on the melting characteristics of mould powders was evaluated. Using X‐ray diffraction, different types of carbon were quantitatively characterized in terms of their internal structure and reactivity experiments were conducted to investigate potential relationships between the structural morphology of carbons and their reactivity. High temperature microscopy and drip test experiments were then used to investigate the melting behaviour of mould powders containing different carbonaceous materials. From the results obtained, correlations were established between the structural factors, chemical reactivity and melting behaviour.
A Hybrid Model of Steel Refining in The Ladle Furnace
Authors: Kargul T. , Falkus J. 
Published: November 2010

AbstractThe paper presents the concept of a new mathematical model, which has been used for the simulation of the ladle furnace steel refining process. The structure of the model contains a mathematical description of the steel stirring processes caused by the injection of argon and a thermodynamic description of the reactions occurring at the metal‐slag interface. Both models have been combined into a single hybrid model, using the SimuSage package. The hybrid model has served as the basis for the creation of a proprietary simulation tool, which has been used to assess the effectiveness of the metal bath desulfurization process in the ladle furnace. The applied mathematical description of the processes occurring in the ladle furnace enables the process simulation to be carried out in real time. The constructed model has been verified in industrial conditions for a ladle furnace of 140 t capacity.
Thirty‐Day Morbidity and Mortality of the Laparoscopic Ileal Interposition Associated with Sleeve Gastrectomy for the Treatment of Type 2 Diabetic Patients with BMI <35: An Analysis of 454 Consecutive Patients
Authors: DePaula Aureo L. , Stival Alessandro , Halpern Alfredo , Vencio Sergio 
Published: November 2010

AbstractBackgroundThe objective of this study was to evaluate the early results of the laparoscopic interposition of a segment of ileum associated with a sleeve gastrectomy (LII‐SG) in order to treat patients with type 2 diabetes mellitus (T2DM) and BMI <35. Data regarding morbidly obese diabetic patients subjected to surgery has consistently been validated. To date, there is scarce information about morbidity and mortality related to the surgical treatment of a “true” typical diabetic population with BMI <35.MethodsThe procedures were performed in 454 patients (322 male, 132 female). Mean age was 53.6 ± 8 years (range = 27–75). Mean BMI was 29.7 ± 3.6 kg/m2 (range = 19–34.8). All patients had the diagnosis of T2DM for at least 3 years. Insulin therapy was used by 45.6% of patients. Mean duration of T2DM was 10.8 ± 5.9 years (range = 3–35). Mean hemoglobin A1c was 8.8 ± 1.9%. Dyslipidemia was observed in 78.4%, hypertension in 64.8%, nephropathy in 28.6%, retinopathy in 32.6%, neuropathy in 34.6%, and coronary heart disease in 13%.ResultsThere was no conversion to open surgery. All patients were evaluated postoperatively. Mortality was 0.4%. There were 29 major complications (6.4%) in 22 patients (4.8%) and 51 minor complications (11.2%). Reoperations were performed on 8 patients (1.7%). Twenty patients (4.4%) were readmitted to the hospital. Mean postoperative BMI was 25.8 ± 3.5 kg/m2. Mean fasting plasma glucose decreased from 198 ± 69 to 128 ± 67 mg/dl and mean postprandial plasma glucose decreased from 262 ± 101 to 136 ± 43 mg/dl.ConclusionsThe laparoscopic ileal interposition associated with a sleeve gastrectomy was considered a safe operation with low rates of morbidity and mortality in a diabetic population with BMI < 35. An early control of postprandial glycemia was observed.
Clinical and Histopathological Characteristics of Hyperparathyroidism‐induced Hypercalcemic Crisis
Authors: Starker Lee F. , Björklund Peyman , Theoharis Constantine , Long William D. , Carling Tobias , Udelsman Robert 
Published: November 2010

AbstractBackgroundThe clinical and pathological characteristics of hyperparathyroidism‐induced hypercalcemic crisis (HIHC) are incompletely described. The present study was designed to elucidate the nature and effects of HIHC in patients undergoing parathyroidectomy in our unit.MethodsA prospective database of 1,754 consecutive patients with primary hyperparathyroidism (PHPT) who underwent parathyroidectomy from 1991–2009 identified 67 (41 women) patients presenting with HIHC. Hyperparathyroidism‐induced hypercalcemic crisis was defined as symptoms and signs of acute calcium intoxication with a concomitant total albumin corrected calcium level >13.5 mg/dl (range: 8.8–10.2 mg/dl). Clinical and pathological characteristics were evaluated. Data are expressed as mean ± SEM.ResultsMean age at presentation was 56.7 ± 2.2 years. Twenty‐four of 67 patients (35%) required preoperative in‐hospital management. Of these, all were treated with saline resuscitation, whereas 20/24 (83%) were treated pharmacologically. Neurocognitive derangements and nephrolithiasis with associated hematuria were the most common presenting symptoms and signs. Preoperative serum calcium and the intact parathyroid hormone level (PTH) were 14.0 ± 0.19 mg/dl and 393 ± 43 pg/ml (reference range: 12–65 pg/ml), respectively. Minimally invasive parathyroidectomy under local cervical block was performed in 28/67 patients (42%); the remainder underwent standard cervical exploration. All patients had postoperative normalization of serum calcium and intact PTH. Hyperparathyroidism‐induced hypercalcemic crisis was due to parathyroid carcinoma in 3/67 patients (4.5%), whereas the remainder of patients displayed a single parathyroid adenoma (n = 57) or multiglandular hyperplasia (n = 7). Histopathological evaluation from HIHC patients revealed a chief cell microcystic pattern in 15/21 (71.4%) of examined parathyroid tumors.ConclusionsHyperparathyroidism‐induced hypercalcemic crisis is most commonly due to a single parathyroid adenoma, often associated with a microcystic histopathological pattern. The condition is optimally managed with saline hydration and urgent parathyroidectomy.