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1.
D.R. Santos‐Peñate C.M. Campos‐Rodríguez J.A. Moreno‐Pérez 《International Transactions in Operational Research》2019,26(1):340-363
The ‐centroid problem or leader–follower problem is generalized considering different customer choice rules where a customer may use facilities belonging to different firms, if the difference in travel distance (or time) is small enough. Assuming essential goods, some particular customer choice rules are analyzed. Linear programming formulations for the generalized ‐medianoid and ‐centroid problems are presented and an exact solution approach is applied. Some computational examples are included. 相似文献
2.
Andrea Mariela Araya-Sibaja Valdir Soldi Carlos Eduardo Maduro Campos Simone Gonçalves Cardoso 《Drug development and industrial pharmacy》2015,41(5):851-858
Progesterone is a natural hormone steroid used in humans for several treatments and in livestock for artificial insemination, which exhibits two polymorphic forms at ambient conditions: form 1 and form 2. Form 2 is metastable and more soluble than form 1; however, it is not suitable to use as powder raw material because it transforms into form 1 by the effects of grinding. A polymorphic screening of progesterone based on polymer-induced heteronucleation method was performed as an alternative to prepare the metastable form. Polyvinyl alcohol, hydroxypropyl methylcellulose (HPMC), dextran, gelatin, polyisoprene (PI) and acrylonitrile-butadiene (NBR) copolymer were used. Crystals were prepared from 0.5, 10 and 40?mg/mL solutions in acetone at room temperature by solvent evaporation. The samples were characterized by X-ray powder diffraction, differential scanning calorimetry (DSC), scanning electron microcopy and attenuated total reflectance infrared Fourier transform spectroscopy. Form 1 was nucleated from 40?mg/mL solutions on the six polymers and from 10?mg/mL solutions on PI and NBR. The mixture of form 1 and form 2 was obtained from 10?mg/mL solution on HPMC, dextran and gelatin and from 0.5?mg/mL solution crystallizations. Therefore, the polymeric devices, which crystallized the metastable and more soluble polymorph (2) of progesterone, would be a promissory alternative for the pharmaceutical applications. 相似文献
3.
Kinetic,thermodynamic parameters and in vitro digestion of tannase from Aspergillus tamarii URM 7115
Amanda Reges de Sena Tonny Cley Campos Leite Talita Camila Evaristo da Silva Nascimento Anna Carolina da Silva Catiane S. Souza Antônio Fernando de Mello Vaz 《Chemical Engineering Communications》2018,205(10):1415-1431
Tannase is an enzyme used in various industries and produced by a large number of microorganisms. The aim of this study was to evaluate tannase production to determine the biochemical, kinetic, and thermodynamic properties and to simulate tannase in vitro digestion. The tannase-producing fungal strain was isolated from “jamun” leaves and identified as Aspergillus tamarii. Temperature at 26°C for 67?h was the best combination for maximum tannase activity (6.35-fold; initial activity in Plackett–Burman design—15.53?U/mL and average final activity in Doehlert design—98.68?U/mL). The crude extract of tannase was optimally active at 40°C, pH 5.5 and 6.5. Moreover, tannase was stimulated by Na+, Ca2+, Mg2+, and Mn2+. The half-life at 40°C lasted 247.55?min. The free energy of Gibbs, enthalpy, and entropy, at 40°C, was 81.47, 16.85, and ?0.21?kJ/mol?·?K, respectively. After total digestion, 123.95% of the original activity was retained. Results suggested that tannase from A. tamarii URM 7115 is an enzyme of interest for industrial applications, such as gallic acid production, additive for feed industry, and for beverage manufacturing, due to its catalytic and thermodynamic properties. 相似文献
4.
Phospholamban (PLN) was expressed in Escherichia coli as a protein fusion with glutathione S-transferase (GST). GST-PLN was mostly present in the insoluble protein fraction and accounted for approximately 50% of total insoluble protein. Attempts to suppress inclusion body formation or to use GST as an affinity-purification tag failed. A successful purification method is based on preparative SDS/PAGE and electrodialysis. From 1 g cells we typically purified 13.5 mg fusion protein with a PLN content of 2.8 mg. We genetically inserted an enterokinase (EK) protease site just in front of the PLN sequence and demonstrated the proteolytical liberation of PLN from the carrier protein. The approach described represents a substantial advancement in PLN expression and purification. 相似文献
5.
JE Dick 《Canadian Metallurgical Quarterly》1996,3(6):405-409
Much of our understanding of the organization of the cells that comprise the hematopoietic system and the cellular and molecular mechanisms that regulate their development is derived from mouse models. However, knowledge of the human hematopoietic system and identification of human stem cells have, until recently, been hampered by the absence of in vivo assays that measure their repopulation capacity. The development of methods to transplant normal and leukemic human hematopoietic cells into immune-deficient SCID mice provides the foundation for human stem cell assays. This review will focus on recent evidence that normal and leukemic human stem cells can be assayed in these systems. 相似文献
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7.
A high prevalence of epilepsy (up to 1.3%) was observed in an area hyperendemic for onchocerciasis in the province of Bururi, Burundi. Following this observation, epileptics and controls were examined in 2 communes (administrative units) with different endemicity for onchocerciasis. Altogether, onchocerciasis was more frequent in epileptics (81.8%) than in controls from the same households (68.3%; P < 0.05). This difference was more marked in the hyperendemic area. Other possible causes of epilepsy, including cysticercosis, were infrequent (18 possible cases among 110 epileptics). During this survey, 9 epileptics with growth retardation were seen. They showed most characteristics of Nakalanga syndrome, which was described from Uganda. All 9 such cases were suffering from onchocerciasis. These findings give more evidence of a possible association between onchocerciasis and epilepsy, and between onchocerciasis and Nakalanga syndrome. 相似文献
8.
N Sobel V Prabhakaran JE Desmond GH Glover EV Sullivan JD Gabrieli 《Canadian Metallurgical Quarterly》1997,78(1-2):115-123
A method for generating olfactory stimuli for humans within a functional magnetic resonance imaging (fMRI) experimental design is described. The system incorporates a nasal-mask in which the change from odorant to no-odorant conditions occurs in less than 500 ms and is not accompanied by visual, auditory, tactile, or thermal cues. The mask provides an ordorant-free environment following prolonged ordorant presence. Specific imaging parameters that are conducive to the study of the human olfactory system are described. In a pilot study performed using these methods, the specific patterns of activation observed converged with published experimental and clinical findings. 相似文献
9.
A preliminary report presenting the results of fibular strut grafting in the severely resorbed mandibular and maxillary region is presented. Thirteen patients were treated due to severe resorption of alveolar and basilar bone of 49 segments of the mandible and the maxilla. Two patients additionally had pathological fractures of the mandible. In 10 cases the strut graft was harvested by means of a new minimally invasive technique. After modelling the fibular bone it was fixed to the recipient site by miniscrews or implants. After a mean follow-up period of 20 months (max. 31, min. 11 months) a retrospective analysis of clinical and radiological findings was carried out. It showed that a mean augmentation of 16 mm was achieved. Compared to other studies the fibular strut graft was resorbed less, and due to the primary stability it could be used for the treatment of fractures of the mandible. No more than natural resorption was observed when the patients received their prostheses fixed to dental implants. 相似文献
10.