System constant and its significance in industrial crystallisation

1979 ◽  
Vol 44 (12) ◽  
pp. 3549-3554 ◽  
Author(s):  
Jaroslav Nývlt ◽  
Miroslav Broul
Keyword(s):  
Steady State ◽  
Nucleation Rate ◽  
Derived Relations ◽  
Specific Output ◽  
Simple Arrangement ◽  
Mean Size ◽  
General Derivation ◽  
The Mean ◽  
Fundamental Equations ◽  
Selection Of

Fundamental equations describing behaviour of the continuous stirred crystalliser in steady state include a system constant B, whose value strongly depends on selection of the size of initial crystals LN. To avoid this dependence and to see that the equations be applicable for crystalliser design also in the case when the value LN approaches zero, a general derivation of the dependence between the mean size of crystals L and specific output of the crystalliser mc has been derived on basis of the numerical nucleation rate. The derived relations do not include the quantity LN and they can be transformed by a simple arrangement to the published relations.

Scale-up of agitated crystallizers; Cooling batch crystallization of potassium aluminium sulphate

1982 ◽  
Vol 47 (4) ◽  
pp. 1189-1194 ◽  
Author(s):  
Jaroslav Nývlt ◽  
Piotr Karpiński ◽  
Stanislav Žáček ◽  
Miloslav Karel ◽  
Jerzy Budz ◽  
...  
Keyword(s):  
Experimental Error ◽  
Scale Up ◽  
Laboratory Scale ◽  
Small Scale ◽  
Sieve Analysis ◽  
Aluminium Sulphate ◽  
Derived Relations ◽  
Batch Crystallization ◽  
Mean Size ◽  
The Mean

The crystallization of potassium aluminium sulphate was conducted by cooling a solution saturated at 70°C to a temperature of 25°C at three various cooling rates. The measurements were performed on a small scale (160 cm3) and a large laboratory scale (0.021 m3). The mean size of product crystals was determined by sieve analysis, and the system constant, BN, was calculated using previously derived relations. The BN value is the same, within experimental error, for all the experiments and scales, indicating that agitated-vessel cooling crystallizers can be modelled successfully even on a very small laboratory scale.

scholarly journals THE RESULTS OF 600 TRANSANAL ENDOSCOPIC SURGERIES OF RECTAL ADENOMAS AND ADENOCARCINOMAS

2019 ◽  
Vol 18 (3(69)) ◽  
pp. 20-40
Author(s):  
E. A. Khomyakov ◽  
S. V. Chernyshov ◽  
E. G. Rybakov ◽  
O. A. Maynovskaya ◽  
Yu. A. Shelygin
Keyword(s):  
Rectal Cancer ◽  
Local Recurrence ◽  
R0 Resection ◽  
Safe Method ◽  
Mean Size ◽  
The Mean ◽  
Mean Time ◽  
Russian Medical ◽  
Selection Of Patients ◽  
Selection Of

AIM: transanal endomicrosurgery (TEM) is the method of choice for local excision of rectal cancer. The presented series of patients is collected prospectively and is the largest of the published in the Russian medical periodicals. PATIENTS AND METHODS: six-hundred patients [average age ±σ 59.8±9 (31-90) years old; 375/600 (62.5%) – women]with rectal adenomas and adenocarcinomas, who underwent TEM in 2011-2019. RESULTS: the mean size of the removed tumors was 3.4±1.5 cm (0.5-10.0). R0 resection was performed in 571/600 (95.2%) of the cases. The complication rate was 3.6% (22/600). Pathomorphological study of the removed specimens revealed adenoma in 450/600 (75.0%) patients, adenocarcinoma in 150/600 (25.0%) cases. The mean time of observation of patients with adenomas was 38.4±25.1 months, with adenocarcinomas – 33.4±23.8 months. The rate of local recurrence in adenomas was 4.5%. Loco-regional recurrence of adenocarcinoma pT1 after TEM was revealed in 6.8% of patients and 30% of pT2 patients without adjuvant treatment. CONCLUSION: TEM is an effective and safe method of treatment of rectal adenomas. With rectal cancer, a thorough selection of patients is required.

Effect of the rate of stirring on crystal size in precipitating or salting-out systems

1986 ◽  
Vol 51 (8) ◽  
pp. 1609-1617 ◽  
Author(s):  
Jaroslav Nývlt ◽  
Stanislav Žáček
Keyword(s):  
Simple Model ◽  
Nucleation Rate ◽  
Crystal Size ◽  
Interfacial Area ◽  
Dissipated Energy ◽  
Potassium Sulphate ◽  
Salting Out ◽  
Derived Relations ◽  
Series Of Experiments ◽  
The Mean

A simple model is proposed to express the dependence of the mean crystal size on the rate of stirring in precipitating or salting-out systems. The nucleation rate is taken to be proportional to the interfacial area of segregated regions. This area is a function of the dissipated energy. The derived relations are applied to results of a series of experiments in which aluminium-potassium sulphate was salted out by the addition of aqueous solutions of methyl alcohol.

Der Sommer und Herbst 2003 aus phänologischer Sicht | Summer and autumn 2003 from a phenological point of view

2004 ◽  
Vol 155 (5) ◽  
pp. 142-145 ◽  
Author(s):  
Claudio Defila
Keyword(s):  
Time Series ◽  
New Record ◽  
Point Of View ◽  
Late Spring ◽  
Mean Deviation ◽  
Leaf Shedding ◽  
The Mean ◽  
Very High ◽  
Selection Of

The record-breaking heatwave of 2003 also had an impact on the vegetation in Switzerland. To examine its influences seven phenological late spring and summer phases were evaluated together with six phases in the autumn from a selection of stations. 30% of the 122 chosen phenological time series in late spring and summer phases set a new record (earliest arrival). The proportion of very early arrivals is very high and the mean deviation from the norm is between 10 and 20 days. The situation was less extreme in autumn, where 20% of the 103 time series chosen set a new record. The majority of the phenological arrivals were found in the class «normal» but the class«very early» is still well represented. The mean precocity lies between five and twenty days. As far as the leaf shedding of the beech is concerned, there was even a slight delay of around six days. The evaluation serves to show that the heatwave of 2003 strongly influenced the phenological events of summer and spring.

Caracterização da Peneira Média em Clones de Coffea canephora

REVISTA FIMCA ◽  
2018 ◽  
Vol 5 (2) ◽  
pp. 28-31
Author(s):  
Darlan Darlan Sanches Barbosa Alves ◽  
Victor Mouzinho Spinelli ◽  
Marcos Santana Moraes ◽  
Carolina Augusto De Souza ◽  
Rodrigo da Silva Ribeiro ◽  
...  
Keyword(s):  
Genetic Improvement ◽  
Block Design ◽  
Coffea Canephora ◽  
Coffee Production ◽  
Randomized Block Design ◽  
Significant Difference ◽  
The Mean ◽  
Four Blocks ◽  
Selection Of

Introdução: O estado de Rondônia se destaca como tradicional produtor de café, sendo o segundo maior produtor brasileiro de C. canephora. No melhoramento genético de C. canephora, a seleção de plantas de elevada peneira média está associada à bebida de qualidade superior. Objetivos: O objetivo desse estudo foi avaliar a variabilidade genética de clones de C. canephora para o tamanho dos grãos, mensurado a partir da avaliação da peneira média (PM). Materiais e Métodos: Para isso, foi conduzido ao longo de dois anos agrícolas experimento no campo experimental da Embrapa no município de Ouro Preto do Oeste-RO, para a avaliação da peneira média de 130 genótipos (clones) com características das variedades botânicas Conilon, Robusta e híbridos intervarietais. O delineamento experimental utilizado foi de blocos ao acaso, com quatro repetições de quatro plantas por parcela. Resultados: Não houve resultados significativos para a interação clones X anos, indicando uma maior consistência no comportamento das plantas ao longo do tempo. Porém foram observadas diferenças significativas para o tamanho dos grãos entre os genótipos avaliados, possibilitando selecionar genótipos superiores. Conclusão: Os genótipos agruparam-se em cinco classes de acordo com o teste de média, subsidiando a caracterização de um gradiente de variabilidade da característica avaliada ABSTRACTIntroduction: Coffea canephora accounts for approximately 35% of the world's coffee production. The state of Rondônia stands out as a traditional coffee producer, being the second largest Brazilian producer of C. canephora. In the classical genetic improvement of C. anephora, the selection of plants of high average sieve is associated with a drink of superior quality. Objectives: The objective of this udy was to evaluate the genetic variability of Coffea canephora clones for the agronomic medium sieve (PM). Materials and Methods: The experiment was conducted in the experimental field of Embrapa, municipality of OuroPreto do Oeste-RO, located at coordinates 10º44'53 "S and 62º12'57". One hundred thirty genotypes (clones) of botanical characteristics Conilon, Robusta and intervarietal hybrids were evaluated in the agricultural years 2013-2014 and 2014-2015. The experimental design was a randomized block design with four blocks and four plants per plot, spacing 3.5 x 1.5 meters between plants. Results: Significant difference was found for the grain size. According to the F test, at 5% probability, the genotypes were grouped into five classes according to the mean test. Conclusion: The results obtained subsidized the characterization of a variability gradient of the evaluated trait.

Selection of one-dimensional sedimentation: models for on-line use

1995 ◽  
Vol 31 (2) ◽  
pp. 193-204 ◽  
Author(s):  
Koen Grijspeerdt ◽  
Peter Vanrolleghem ◽  
Willy Verstraete
Keyword(s):  
Steady State ◽  
Selection Criteria ◽  
Data Sets ◽  
Concentration Profiles ◽  
A Posteriori ◽  
One Dimensional ◽  
On Line ◽  
Dynamic Concentration ◽  
Selection Of ◽  
Modelling Task

A comparative study of several recently proposed one-dimensional sedimentation models has been made. This has been achieved by fitting these models to steady-state and dynamic concentration profiles obtained in a down-scaled secondary decanter. The models were evaluated with several a posteriori model selection criteria. Since the purpose of the modelling task is to do on-line simulations, the calculation time was used as one of the selection criteria. Finally, the practical identifiability of the models for the available data sets was also investigated. It could be concluded that the model of Takács et al. (1991) gave the most reliable results.

Batch Precipitation of Lead Iodide

1994 ◽  
Vol 59 (6) ◽  
pp. 1301-1304
Author(s):  
Jaroslav Nývlt ◽  
Stanislav Žáček
Keyword(s):  
Aqueous Solution ◽  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Crystal Size ◽  
Lead Nitrate ◽  
Lead Iodide ◽  
Constant Rate ◽  
Mean Size ◽  
The Mean

Lead iodide was precipitated by a procedure in which an aqueous solution of potassium iodide at a concentration of 0.03, 0.10 or 0.20 mol l-1 was stirred while an aqueous solution of lead nitrate at one-half concentration was added at a constant rate. The mean size of the PbI2 crystals was determined by evaluating the particle size distribution, which was measured sedimentometrically. The dependence of the mean crystal size on the duration of the experiment exhibited a minimum for any of the concentrations applied. The reason for this is discussed.

scholarly journals Effects of topical gel formulation of Ficus carica latex on cutaneous leishmaniasis induced by Leishmania major in BALB/c mice

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Ali Pouryousef ◽  
Erfan Eslami ◽  
Sepehr Shahriarirad ◽  
Sina Zoghi ◽  
Mehdi Emami ◽  
...  
Keyword(s):  
Cutaneous Leishmaniasis ◽  
Murine Model ◽  
Leishmania Major ◽  
Considerable Effect ◽  
Ficus Carica ◽  
Control Group ◽  
Topical Gel ◽  
The Third ◽  
Mean Size ◽  
The Mean

Abstract Objectives The current study aimed to evaluate the effects of Ficus carica latex on the treatment of cutaneous leishmaniasis (CL), induced by Leishmania major. A 5% topical gel with F. carica latex was prepared. BALB/c mice were infected by inoculation of amastigotes form of L. major. Thirty BALB/c mice were divided into five groups, where the first group was treated daily, the second group twice per day, and the third group every other day with the 5% topical gel, for 3 weeks. The sizes of the lesions were measured before and during the course of treatment. Results Although the mean size of lesions in the mice group treated with the 5% F. carica gel, especially in the group receiving daily treatment, was less than the mean size of the lesions in the control group, yet, the differences was not statistically significant (p > 0.05). The findings of the current study demonstrated that the 5% F. carica latex with a 3-week course of treatment had no considerable effect in recovery or control of CL induced by L. major in the murine model. Using higher concentration of F. carica latex and with longer treatment lengths may increase its efficacy in the treatment of CL.

SET-VALUED PERFORMANCE APPROXIMATIONS FOR THE QUEUE GIVEN PARTIAL INFORMATION

2020 ◽  
pp. 1-23
Author(s):  
Yan Chen ◽  
Ward Whitt
Keyword(s):  
Steady State ◽  
Decay Rate ◽  
Waiting Time ◽  
Partial Information ◽  
Upper And Lower Bounds ◽  
Interarrival Time ◽  
Limited Information ◽  
Wide Range ◽  
The Mean ◽  
Third Moment

In order to understand queueing performance given only partial information about the model, we propose determining intervals of likely values of performance measures given that limited information. We illustrate this approach for the mean steady-state waiting time in the $GI/GI/K$ queue. We start by specifying the first two moments of the interarrival-time and service-time distributions, and then consider additional information about these underlying distributions, in particular, a third moment and a Laplace transform value. As a theoretical basis, we apply extremal models yielding tight upper and lower bounds on the asymptotic decay rate of the steady-state waiting-time tail probability. We illustrate by constructing the theoretically justified intervals of values for the decay rate and the associated heuristically determined interval of values for the mean waiting times. Without extra information, the extremal models involve two-point distributions, which yield a wide range for the mean. Adding constraints on the third moment and a transform value produces three-point extremal distributions, which significantly reduce the range, producing practical levels of accuracy.

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