scholarly journals Холодне витягування з потоншенням сталевих порожнистих виробів

2020 ◽  
pp. 50-56
Author(s):  
A. V. Kalyuzhny ◽  
V. L. Kalyuzhny ◽  
D. A. Kartamishev
Keyword(s):  
C 50

Калюжний О. В., Калюжний В. Л., Картамишев Д. О. Холодне витягування з потоншенням сталевих порожнистих виробів. Oбробка матеріалів тиском. 2020. № 1 (50). C. 50-56. Приведені результати моделювання методом скінченних елементів процесу холодного штампування порожнистого виробу з маловуглецевої сталі з інтенсивним пропрацюванням пластичною деформацією стінки для набуття необхідних механічних властивостей. Штампування складається з двох переходів. В якості вихідної заготовки використана конусна чашка з виступами на донній частині з боку порожнини і на нижньому торці. На першому переході витягуванням із потоншенням через три послідовно розташовані матриці отримується порожнистий напівфабрикат з циліндричною зовнішньою поверхнею ы стінкою змінної товщини по висоті. На другому переході витягуванням із потоншенням через одну матрицю і доштампуванням донної частини отримані кінцеві форма і розміри виробу з фланцем. Для вибору обладнання і проектування штампового оснащення на кожному переході встановлені залежності зусилля деформування від переміщення пуансонів, розподіл питомих зусиль на деформуючому інструменті. Пропрацювання структури металу холодною пластичною деформацією оцінене за величиною інтенсивності деформацій та ступеню використання ресурсу пластичності. Встановлені ступені деформації для здійснення витягування із потоншенням без руйнування в послідовно розташованих трьох матрицях. Приведені розподіли температури здеформованого металу при витягуванні на першому переході та витягуванні і доштампуванні на другому переході. Виявлені кінцеві форма і розміри виробу. По величині інтенсивності деформацій і використанням діаграми істинних напружень виконане прогнозування напруження текучості здеформованого металу по висоті стінки і в місці переходу стінки у донну частину.

On the Preparation of Bovine α-Thrombin

1978 ◽  
Vol 39 (01) ◽  
pp. 193-200 ◽  
Author(s):  
Erwin F Workman ◽  
Roger L Lundblad
Keyword(s):  
Immobilized Enzyme ◽  
Catalytic Properties ◽  
Specific Activity ◽  
Guanidine Hydrochloride ◽  
Low Molecular Weight ◽  
Reversible Process ◽  
Gel Beads ◽  
Tissue Thromboplastin ◽  
C 50 ◽  
Hydrolysis Of

SummaryAn improved method for the preparation of bovine α-thrombin is described. The procedure involves the activation of partially purified prothrombin with tissue thromboplastin followed by chromatography on Sulfopropyl-Sephadex C-50. The purified enzyme is homogeneous on polyacrylamide discontinuous gel electrophoresis and has a specific activity toward fibrinogen of 2,200–2,700 N.I.H. U/mg. Its stability on storage in liquid media is dependent on both ionic strenght and temperature. Increasing ionic strength and decreasing temperature result in optimal stability. The denaturation of α-thrombin by guanidine hydrochloride was found to be a partially reversible process with the renatured species possessing properties similar to “aged” thrombin. In addition, the catalytic properties of a-thrombin covalently attached to agarose gel beads were also examined. The activity of the immobilized enzyme toward fibrinogen was affected to a much greater extent than was the hydrolysis of low molecular weight, synthetic substrates.

Plasminogen-Activator in Human Early Milk: Its Partial Purification and Characterization

1981 ◽  
Vol 45 (02) ◽  
pp. 121-126 ◽  
Author(s):  
Utako Okamoto ◽  
Noboru Horie ◽  
Yoko Nagamatsu ◽  
Jun-Ichiro Yamamoto
Keyword(s):  
Plasminogen Activator ◽  
Polyacrylamide Gel Electrophoresis ◽  
Gel Filtration ◽  
Partial Purification ◽  
Order Kinetic ◽  
Diisopropyl Fluorophosphate ◽  
Step Procedure ◽  
Activity Band ◽  
C 50 ◽  
Gel Isoelectric Focusing

SummaryMilk plasminogen-activator was partially purified from human transitional milk collected at about 10 days after delivery, by a five-step procedure involving chloroform treatment, ammonium sulfate precipitation, and column chromatography on Sephadex G-150, CM Sephadex C-50 and DEAE Sephadex A-50. This gave milk-activator with a maximum purification factor of about 2,400-fold with respect to the skimmed milk. The CM Sephadex-step preparation showed, on polyacrylamide gel electrophoresis, a single plasminogen-activator activity band located between the bands of albumin and prealbumin of human serum. This preparation exhibited no kinin forming activity. The activator hydrolyzed acetyl-glycyl-L-lysine methyl ester with similar order kinetic constants to urokinase, and was inhibited strongly by diisopropyl-fluorophosphate. The molecular weight of the activator as estimated by gel filtration was approximately 86,000, the isoelectric points as estimated by gel isoelectric focusing were pH 7.2, 6.9 and 6.6, and the activator activity was not quenched by antiurokinase globulin, indicating that the milk-activator is a different entity from urokinase.

Avaliação e otimização das condições de obtenção do ácido acetilsalicílico para fins didáticos

2019 ◽  
Vol 30 (2) ◽  
pp. 54
Author(s):  
Leslie Tauany Schneider da Luz ◽  
Sandra Inês Adams Angnes Gomes ◽  
Marilei Casturina Mendes Sandri ◽  
Flávia De Mello ◽  
Juliana Aparecida Bolzan
Keyword(s):  
C 50

A síntese do ácido acetilsalicílico (AAS) é muito empregada em aulas experimentais de Química para explorar o ensino de reações nucleofílicas e o processo de purificação por recristalização. Considerando a diversidade de protocolos disponíveis na literatura, com divergências nas condições experimentais, este trabalho teve como objetivo otimizar as condições de tempo e temperatura da síntese do AAS e, concomitante, melhorar a verdura química do processo visando maior eficiência mássica e energética, de acordo com os princípios 1, 2 e 6 da Química Verde (QV). Para isso, propôs-se a síntese de AAS a temperaturas de 40 °C, 50 °C, 60 °C, 70 °C, 80 e 90 °C durante 10, 20, 30 e 40 minutos de reação. Os resultados apontam que o AAS obtido em 20 minutos a 80°C apresentou os melhores resultados: um bom rendimento, 77,70 ± 0,01 %, com ponto de fusão 133 °C-134 °C, com Eficiência de Massa 24 % e Fator E 3,10; as melhores métricas de energia, <em>Throughput</em> 0,101 g min<sup>-1</sup><em>, </em>Intensidade de Tempo  9,869 min g<sup>-1</sup>, Intensidade de Energia 0,073 Kw h g<sup>-1</sup> e o  menor consumo de energia, 0,1485 KWh, um ganho de eficiência energética de aproximadamente 200 %, contribuindo principalmente com melhorias no P6 da QV.

Circular dichroism and infrared study of β-turn formation in repeat peptides of elastin

1987 ◽  
Vol 52 (5) ◽  
pp. 1356-1361
Author(s):  
S. Abdel Rahman ◽  
M. Elsafty ◽  
A. Hattaba
Keyword(s):  
Circular Dichroism ◽  
Solid State ◽  
Ir Spectra ◽  
Chain Length ◽  
Room Temperature ◽  
Infrared Study ◽  
Feature Characteristic ◽  
C 50 ◽  
The Stability ◽  
Circular Dichroïsm

The conformation of elastin-like peptides Boc-Ala-Pro-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Ala-Pro-Gly-Val-Gly-Val-APEGM, Boc-Ala-Pro-Gly-Val-Gly-Val-Ala-Pro-Gly-Val-Gly-Val-APEGM were examined in solution using circular dichroism at 30 °C, 50 °C, and 70 °C and in solid state by IR at room temperature. The studies show that the β-turn is a significant conformational feature for peptides under investigation in solution at 30 °C and 50 °C, but at 70 °C the tetra, hexa, and decapeptides show the CD feature characteristic of the β-structure while the dodecapeptide spectra show the presence of β-turn which indicates the stability of the β-turn at this chain length. The IR spectra show that in the solid state at room temperature all investigated peptides assume essentially a β-turn except the tetrapeptide which present evidence of antiparallel β-structure. The β-turn contribution in the IR spectra increases with the increase of the chain length of the peptide.

scholarly journals In Situ Thermal-Stage Fitted-STEM Characterization of Spherical-Shaped Co/MoS2 Nanoparticles for Conversion of Heavy Crude Oils

Catalysts ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1239
Author(s):  
Manuel Ramos ◽  
Félix Galindo-Hernández ◽  
Brenda Torres ◽  
José Manuel Domínguez-Esquivel ◽  
Martin Heilmaier
Keyword(s):  
Molybdenum Disulfide ◽  
Sodium Molybdate ◽  
Interlayer Spacing ◽  
Scanning Transmission Electron Microscope ◽  
Interplanar Distance ◽  
Scanning Transmission ◽  
Heavy Crude ◽  
C 50 ◽  
Nano Catalysts

We report the thermal stability of spherically shaped cobalt-promoted molybdenum disulfide (Co/MoS2) nano-catalysts from in-situ heating under electron irradiation in the scanning transmission electron microscope (STEM) from room temperature to 550 °C ± 50 °C with aid of Fusion® holder (Protochip©, Inc.). The catalytic nanoparticles were synthesized via a hydrothermal method using sodium molybdate (Na2MoO4·2H2O) with thioacetamide (CH3CSNH2) and cobalt chloride (CoCl2) as promoter agent. The results indicate that the layered molybdenum disulfide structure with interplanar distance of ~0.62 nm remains stable even at temperatures of 550 °C, as observed in STEM mode. Subsequently, the samples were subjected to catalytic tests in a Robinson Mahoney Reactor using 30 g of Heavy Crude Oil (AGT-72) from the golden lane (Mexico’s east coast) at 50 atm using (ultrahigh purity) UHP hydrogen under 1000 rpm stirring at 350 °C for 8 h. It was found that there is no damage on the laminar stacking of Co/MoS2 with temperature, with interlayer spacing remaining at 0.62 nm; these sulfided catalytic materials led to aromatics rise of 22.65% and diminution of asphaltenes and resins by 15.87 and 3.53%, respectively.

VP39 The Alphabet Lottery? How NICE Outcomes Vary By Appraisal Committee

2019 ◽  
Vol 35 (S1) ◽  
pp. 86-86
Author(s):  
Richard Macaulay ◽  
Lok Wan Liu ◽  
Cornelia Roibu ◽  
Andrea Berardi
Keyword(s):  
Cost Effectiveness ◽  
The Other ◽  
Appraisal Committee ◽  
Technology Appraisal ◽  
The Public ◽  
Chi Squared ◽  
C 50 ◽  
To Receive ◽  
Disciplinary Group ◽  
53 C 55

IntroductionNICE (National Institute for Health and Care Excellence) makes recommendations on the public reimbursement of medicines based on their clinical- and cost-effectiveness. The recommendation is made by an Appraisal Committee (comprising a multi-disciplinary group of independent experts) as part of a technology appraisal. There are four Appraisal Committees (A,B,C,D); this research investigates whether appraisal outcomes vary by committee.MethodsAll publicly-available Final Appraisal Determinations from NICE Single Technology Appraisals (STA) were screened (01/10/2009-14/11/2018) and key data were extracted. Homogeneity in rates of acceptance or rejection across the committees was assessed using Chi-squared tests.ResultsThe Appraisal Committee was identified for 298 technologies, 56% (168/298) of which were ‘recommended’. The number of technologies assessed by each committee was similar (A:79, B:62, C:91, D:66). However, STAs conducted by Committee D were significantly less likely to receive ‘recommended’ outcomes (A:68% [54/79], B:65% [40/62], C:53% [48/91], D:39% [26/66]; p < 0.01). STAs for oncology indications had higher ’not recommended’ outcomes than those for non-oncology indications (25% vs. 9%). The lower ‘recommendation’ rates for committee D persisted across oncology (A:60%, B:83%, C:50%, D:38%; p = 0.01) and non-oncology indications (A:73%, B:53%, C:55%, D:40%; p < 0.01). However, STAs conducted by Committee D were significantly more likely to receive ‘optimized’ recommendations (A:16%, B:21%, C:33%, D: 36%; p < 0.01) and when considering the rates of ‘recommended’ and ‘optimized’ outcomes compared to ‘only in research’ and ‘not recommended’ outcomes, no significant differences were found (A:85%, B: 85%, C:86%, D:76%; p = 0.27).ConclusionsSTAs undertaken by NICE Appraisal Committee D was associated with a significantly lower rate of ‘recommended’ outcomes but tended to an ‘optimized’ recommendation significantly more than the other committees. Further research is needed to determine if this reflects any deviation in uniform implementation of NICE methodology between Committees.

A Numerical Approach to Determine Some Properties of Cylindrical Pieces of Bananas During Drying

2015 ◽  
Vol 11 (3) ◽  
pp. 335-347 ◽  
Author(s):  
Wilton Pereira da Silva ◽  
Cleide M. D. P. S. e Silva ◽  
Aluizio Freire da Silva Junior ◽  
Alexandre José de Melo Queiroz
Keyword(s):  
Numerical Solution ◽  
Numerical Approach ◽  
Moisture Diffusivity ◽  
Convective Drying ◽  
Chi Square ◽  
Experimental Conditions ◽  
Liquid Diffusion ◽  
Air Temperatures ◽  
C 50 ◽  
Volume Method

Abstract This article uses several liquid diffusion models to describe convective drying of bananas cut into cylindrical pieces. A two-dimensional numerical solution of the diffusion equation with boundary condition of the third kind, obtained through the finite volume method, was used to describe the process. The cylindrical pieces were cut into the following dimensions: length of about 21 mm and average radius of 15 mm. Drying air temperatures were 40°C, 50°C, 60°C and 70°C. In order to determine the process parameters, an optimizer was coupled with the numerical solution. A model that considers the shrinkage and variable effective moisture diffusivity well describes drying for all the experimental conditions, and enables to predict the moisture distributions at any given time. For this model, the determination coefficient has varied from 0.99937 (70°C) to 0.99995 (40°C), while the chi-square ranged from 3.41 × 10−4 (40°C) to 4.15 × 10−3 (70°C).

Alkali Pre-Treatment Dyeing Technology for Hemp/Cotton/Polyester Knitted Fabric

2014 ◽  
Vol 915-916 ◽  
pp. 871-874 ◽  
Author(s):  
Xian Ping Zeng ◽  
Jin Fa Liu
Keyword(s):  
Cotton Fabric ◽  
Alkali Treatment ◽  
Orthogonal Experiment ◽  
Optimum Process ◽  
Knitted Fabric ◽  
Polyester Mesh ◽  
Liquor Ratio ◽  
Pre Treatment ◽  
C 50

In this paper, the hemp / cotton / polyester mesh knitted fabric (Han / C / T) is treated by alkali treatment, conventional dyeing and alkali pre-treatment dyeing. We have obtained the conclusion that alkali treatment improves the dyeing effect. Alkali pre-treatment dyeing was done after alkali treatment. The fabric dyeing effect is improved obviously. The optimum process come from orthogonal experiment (dyes 2.5% owf, Na2SO4 :30g/L, Na2CO3:10g/L, liquor ratio (1:50) and 90°C×50 min). Through this optimum process, dyeing effect for hemp / cotton / polyester mesh knitted fabric is close to the pure cotton fabric dyeing effect.

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