scholarly journals STUDIES ON PERMEABILITY OF MEMBRANES

1927 ◽  
Vol 10 (4) ◽  
pp. 575-598 ◽  
Author(s):  
L. Michaelis ◽  
W. A. Perlzweig
Keyword(s):  
Aqueous Solution ◽  
Diffusion Coefficients ◽  
Potential Difference ◽  
Maximum Value ◽  
The Difference ◽  
The One

The theoretical aspects of the problem of sieve-like membranes are developed. The method of preparing the dried collodion membrane is described, and the method of defining the property of a particular membrane is given. It consists of the measurement of the Co P, that is the P.D. between an 0.1 and an 0.01 M KCl solution separated by the membrane. Co P is in the best dried membranes 50 to 53 millvolts, the theoretically possible maximum value being 55 millivolts. Diffusion experiments have been carried out with several arrangements, one of which is, for example, the diffusion of 0.1 M KNO3 against 0.1 M NaCl across the membrane. The amount of K+ diffusing after a certain period was in membranes with a sufficiently high Co P (about 50 millivolts or more) on the average ten times as much as the amount of diffused Cl-. In membranes with a lower Co P the ratio was much smaller, down almost to the proportion of 1:1 which holds for the mobility of these two ions in a free aqueous solution. When higher concentrations were used, e.g. 0.5 M solution, the difference of the rate of diffusion for K+ and Cl- was much smaller even in the best membranes, corresponding to the fact that the P.D. of two KCl solutions whose concentrations are 10:1 is much smaller in higher ranges of concentration than in lower ones. These observations are confirmed by experiments arranged in other ways. It has been shown that, in general, the diffusion of an anion is much slower than the one of a cation across the dried collodion membrane. The ratio of the two diffusion coefficients would be expected to be calculable in connection with the potential difference of such a membrane when interposed between these solutions. The next problem is to show in how far this can be confirmed quantitatively.

The Effect of Differences in the Diffusion Coefficients of Components on the Onset of Convection in Isothermal Multicomponent Systems

2016 ◽  
Vol 367 ◽  
pp. 96-102
Author(s):  
Vladimir Kossov ◽  
Yuriy Zhavrin ◽  
Olga Fedorenko
Keyword(s):  
Aqueous Solution ◽  
Diffusion Coefficients ◽  
Effective Diffusion ◽  
Gas Mixtures ◽  
Onset Of Convection ◽  
Gaseous Mixtures ◽  
Convective Flows ◽  
Convective Structures ◽  
Pure Salt ◽  
The Difference

Two series of experiments on the formation of convective flows in multicomponent liquid and gaseous mixtures are considered. In the first series, the convective structures arising during the diffusion of a binary aqueous solution of salt and sugar in an aqueous solution of pure salt were studied using the schlieren method. The observed behavior of convective cells corresponds to the instability similar to the "finger structures". In the second series, the experiments were conducted to determine the effective diffusion coefficients as a function of pressure in gas mixtures 0.5504 CH4 + 0.4496 Ar – N2 and 0.5994 H2 + 0.4006 Ar – N2. Our experiments have shown that the onset of convective flows both in liquid and gaseous multicomponent mixtures is due to the difference in the interdiffusion coefficients of the components. The experimental data for the ternary gas mixtures are described in the framework of the linear theory of stability.

Use of a Lyophilized Reference Plasma to Compare Coagulation Test Procedures

1975 ◽  
Vol 34 (02) ◽  
pp. 426-444 ◽  
Author(s):  
J Kahan ◽  
I Nohén
Keyword(s):  
Oral Anticoagulant Therapy ◽  
Repeated Measurements ◽  
Test Procedures ◽  
Coagulation Activity ◽  
Close Relationship ◽  
Measured Activity ◽  
Test Materials ◽  
The Difference ◽  
The Stability ◽  
The One

SummaryIn 4 collaborative trials, involving a varying number of hospital laboratories in the Stockholm area, the coagulation activity of different test materials was estimated with the one-stage prothrombin tests routinely used in the laboratories, viz. Normotest, Simplastin-A and Thrombotest. The test materials included different batches of a lyophilized reference plasma, deep-frozen specimens of diluted and undiluted normal plasmas, and fresh and deep-frozen specimens from patients on long-term oral anticoagulant therapy.Although a close relationship was found between different methods, Simplastin-A gave consistently lower values than Normotest, the difference being proportional to the estimated activity. The discrepancy was of about the same magnitude on all the test materials, and was probably due to a divergence between the manufacturers’ procedures used to set “normal percentage activity”, as well as to a varying ratio of measured activity to plasma concentration. The extent of discrepancy may vary with the batch-to-batch variation of thromboplastin reagents.The close agreement between results obtained on different test materials suggests that the investigated reference plasma could be used to calibrate the examined thromboplastin reagents, and to compare the degree of hypocoagulability estimated by the examined PIVKA-insensitive thromboplastin reagents.The assigned coagulation activity of different batches of the reference plasma agreed closely with experimentally obtained values. The stability of supplied batches was satisfactory as judged from the reproducibility of repeated measurements. The variability of test procedures was approximately the same on different test materials.

The Demand For Money in Pakistan: Reply (Notes and Comments)

1975 ◽  
Vol 14 (3) ◽  
pp. 370-375
Author(s):  
M. A. Akhtar
Keyword(s):  
Interest Rates ◽  
Money Demand ◽  
Strong Support ◽  
Physical Capital ◽  
Careful Examination ◽  
Demand For Money ◽  
Weak Support ◽  
Complementarity Hypothesis ◽  
The Difference ◽  
The One

I am grateful to Abe, Fry, Min, Vongvipanond, and Yu (hereafter re¬ferred to as AFMVY) [1] for obliging me to reconsider my article [2] on the demand for money in Pakistan. Upon careful examination, I find that the AFMVY results are, in parts, misleading and that, on the whole, they add very little to those provided in my study. Nevertheless, the present exercise as well as the one by AFMVY is useful in that it furnishes us with an opportunity to view some of the fundamental problems involved in an empi¬rical analysis of the demand for money function in Pakistan. Based on their elaborate critique, AFMVY reformulate the two hypo¬theses—the substitution hypothesis and the complementarity hypothesis— underlying my study and provide us with some alternative estimates of the demand for money in Pakistan. Briefly their results, like those in my study, indicate that income and interest rates are important in deter¬mining the demand for money. However, unlike my results, they also suggest that the price variable is a highly significant determinant of the money demand function. Furthermore, while I found only a weak support for the complementarity between money demand and physical capital, the results obtained by AFMVY appear to yield a strong support for that rela¬tionship.1 The difference in results is only a natural consequence of alter¬native specifications of the theory and, therefore, I propose to devote most of this reply to the criticisms raised by AFMVY and the resulting reformulation of the two mypotheses.

Effect of leakage and blockage on the acoustic behavior of particle filters

2019 ◽  
Vol 67 (6) ◽  
pp. 483-492
Author(s):  
Seonghyeon Baek ◽  
Iljae Lee
Keyword(s):  
Transfer Matrix ◽  
Particle Filters ◽  
Acoustic Analysis ◽  
Transmission Loss ◽  
One Dimensional ◽  
Filter System ◽  
The Difference ◽  
The One ◽  
Analytical Approaches ◽  
Good Agreement

The effects of leakage and blockage on the acoustic performance of particle filters have been examined by using one-dimensional acoustic analysis and experimental methods. First, the transfer matrix of a filter system connected to inlet and outlet pipes with conical sections is measured using a two-load method. Then, the transfer matrix of a particle filter only is extracted from the experiments by applying inverse matrices of the conical sections. In the analytical approaches, the one-dimensional acoustic model for the leakage between the filter and the housing is developed. The predicted transmission loss shows a good agreement with the experimental results. Compared to the baseline, the leakage between the filter and housing increases transmission loss at a certain frequency and its harmonics. In addition, the transmission loss for the system with a partially blocked filter is measured. The blockage of the filter also increases the transmission loss at higher frequencies. For the simplicity of experiments to identify the leakage and blockage, the reflection coefficients at the inlet of the filter system have been measured using two different downstream conditions: open pipe and highly absorptive terminations. The experiments show that with highly absorptive terminations, it is easier to see the difference between the baseline and the defects.

Development and Validation of Spectrophotometric and Liquid Chromatographic Methods for Estimation of Tigecycline in Injections

2020 ◽  
Vol 13 (5) ◽  
pp. 5148-5154
Author(s):  
Sagar Suman Panda ◽  
Ravi Kumar B.V.V.
Keyword(s):  
Area Under The Curve ◽  
Reversed Phase ◽  
Equal Concentration ◽  
Pharmaceutical Dosage Form ◽  
Liquid Chromatographic Method ◽  
Array Detection ◽  
The Difference ◽  
The One ◽  
Development And Validation ◽  
Liquid Chromatographic

Three new analytical methods were optimized and validated for the estimation of tigecycline (TGN) in its injection formulation. A difference UV spectroscopic, an area under the curve (AUC), and an ultrafast liquid chromatographic (UFLC) method were optimized for this purpose. The difference spectrophotometric method relied on the measurement of amplitude when equal concentration solutions of TGN in HCl are scanned against TGN in NaOH as reference. The measurements were done at 340 nm (maxima) and 410nm (minima). Further, the AUC under both the maxima and minima were measured at 335-345nm and 405-415nm, respectively. The liquid chromatographic method utilized a reversed-phase column (150mm×4.6mm, 5µm) with a mobile phase of methanol: 0.01M KH2PO4 buffer pH 3.5 (using orthophosphoric acid) in the ratio 80:20 %, v/v. The flow rate was 1.0ml/min, and diode array detection was done at 349nm. TGN eluted at 1.656min. All the methods were validated for linearity, precision, accuracy, stability, and robustness. The developed methods produced validation results within the satisfactory limits of ICH guidance. Further, these methods were applied to estimate the amount of TGN present in commercial lyophilized injection formulations, and the results were compared using the One-Way ANOVA test. Overall, the methods are rapid, simple, and reliable for routine quality control of TGN in the bulk and pharmaceutical dosage form. 

Managing the Era of Multi-Cultural Leadership

2018 ◽  
Vol 11 (1) ◽  
Author(s):  
M. Rahul ◽  
R. Ganesan
Keyword(s):  
Work Environment ◽  
Leadership Style ◽  
Work Experience ◽  
Cross Culture ◽  
Cultural Leadership ◽  
Team Members ◽  
Diverse Workforce ◽  
The Difference ◽  
The One ◽  
Global Arena

Leaders in the global arena are the one who face the challenges never seen before, while coordinating work and managing relationship between team members coming from varied ethnic groups. Globalization has undoubtedly opened up endless growth opportunities for both, businesses and individuals, by collaborating with each other, but with certain inherent challenges. These challenges are the difference in the cultural background of the team members, which gets predominantly reflected in their behavior at workplace too. The cultural differences exist primarily due to differences in shared values, which form the basis for difference in perception and practices of decision making by an individual (Hofstede, 1980). Juana Bordas has rightly described that any business that fails to adapt their leadership style aligning with multi-cultural approach will find it difficult to thrive in a more colorful world. Leadership style has witnessed various facets of changing work environment that has demanded from leaders to modify their approach to adapt along and be effective and survive in the ever-changing environment of business (Bordas,2007).A cross-culture leader plays a significant role in knitting the diverse workforce into an efficient team; which requires a leader to very well understand the various dimensions of culture. This understanding of the leader enables him to learn about blending of leadership styles to address the challenges of such work environment. This paper is an extended work on 'Leadership in Cross-Cultural Environment – A Comparison of Asian and Non-Asian Managers' (Rahul and Ganesan, 2015). The extended research study has identified that enhanced work experience of cross-culture leaders enables them in effective team management, than the rise in designation, as it results in creation of hierarchical distance between the leaders and subordinates.

Defending the Difference

2017 ◽  
Keyword(s):  
Social Sciences ◽  
Natural Sciences ◽  
Point Of View ◽  
True Nature ◽  
Natural Entities ◽  
The Social ◽  
The World ◽  
Methodological Difference ◽  
The Difference ◽  
The One

Dreyfus argues that there is a basic methodological difference between the natural sciences and the social sciences, a difference that derives from the different goals and practices of each. He goes on to argue that being a realist about natural entities is compatible with pluralism or, as he calls it, “plural realism.” If intelligibility is always grounded in our practices, Dreyfus points out, then there is no point of view from which one can ask about or provide an answer to the one true nature of ultimate reality. But that is consistent with believing that the natural sciences can still reveal the way the world is independent of our theories and practices.

scholarly journals Theoretical Modelling of Ion Exchange Processes in Glass: Advances and Challenges

2021 ◽  
Vol 11 (11) ◽  
pp. 5070
Author(s):  
Xesús Prieto-Blanco ◽  
Carlos Montero-Orille
Keyword(s):  
Ion Exchange ◽  
Diffusion Coefficients ◽  
Molten Salts ◽  
Theoretical Modelling ◽  
Copper Films ◽  
Theoretical Frameworks ◽  
Self Diffusion ◽  
Exchange Processes ◽  
The One ◽  
Made In

In the last few years, some advances have been made in the theoretical modelling of ion exchange processes in glass. On the one hand, the equations that describe the evolution of the cation concentration were rewritten in a more rigorous manner. This was made into two theoretical frameworks. In the first one, the self-diffusion coefficients were assumed to be constant, whereas, in the second one, a more realistic cation behaviour was considered by taking into account the so-called mixed ion effect. Along with these equations, the boundary conditions for the usual ion exchange processes from molten salts, silver and copper films and metallic cathodes were accordingly established. On the other hand, the modelling of some ion exchange processes that have attracted a great deal of attention in recent years, including glass poling, electro-diffusion of multivalent metals and the formation/dissolution of silver nanoparticles, has been addressed. In such processes, the usual approximations that are made in ion exchange modelling are not always valid. An overview of the progress made and the remaining challenges in the modelling of these unique processes is provided at the end of this review.

scholarly journals Major Elements to Consider in Developing Ammonia Emission Factor at Municipal Solid Waste (MSW) Incinerators

2021 ◽  
Vol 13 (4) ◽  
pp. 2197
Author(s):  
Seongmin Kang ◽  
Joonyoung Roh ◽  
Eui-chan Jeon
Keyword(s):  
Municipal Solid Waste ◽  
Solid Waste ◽  
Emission Factor ◽  
Waste Incineration ◽  
Emission Factors ◽  
Major Elements ◽  
Ammonia Emission ◽  
Nh3 Emission ◽  
The Difference ◽  
The One

NH3 is one of the major substances contributing to the secondary generation of PM2.5; therefore, management is required. In Korea, the management of NH3 is insufficient, and the emission factor used by EPA is the same as the one used when calculating emissions. In particular, waste incineration facilities do not currently calculate NH3 emissions. In the case of combustion facilities, the main ammonia emission source is the De-NOx facility, and, in the case of a power plant with a De-NOx facility, NH3 emission is calculated. Therefore, in the case of a Municipal Solid Waste (MSW) incinerator with the same facility installed, it is necessary to calculate NH3 emissions. In this study, the necessity of developing NH3 emission factors for an MSW incinerator and calculating emission was analyzed. In addition, elements to be considered when developing emission factors were analyzed. The study found that the NH3 emission factors for each MSW incinerator technology were calculated as Stoker 0.010 NH3 kg/ton and Fluidized Beds 0.004 NH3 kg/ton, which was greater than the NH3 emission factor 0.003 NH3 kg/ton for the MSW incinerator presented in EMEP/EEA (2016). As a result, it was able to identify the need for the development of NH3 emission factors in MSW incinerators in Korea. In addition, the statistical analysis of the difference between the incineration technology of MSW and the NH3 emission factor by the De-NOx facility showed a difference in terms of both incineration technology and De-NOx facilities, indicating that they should be considered together when developing the emission factor. In addition to MSW, it is believed that it will be necessary to review the development of emission factors for waste at workplaces and incineration facilities of sewage sludge.

Comparison of a Non Electrostatic Surface Complexation Model and Surface Phase Theories for Prediction of Future Sorption Properties.

2004 ◽  
Vol 824 ◽  
Author(s):  
Allan T. Emrén ◽  
Anna-Maria Jacobsson
Keyword(s):  
Aqueous Solution ◽  
Chemical Potential ◽  
Surface Complexation ◽  
Sorption Properties ◽  
Phase Method ◽  
Detailed Knowledge ◽  
Surface Phase ◽  
Surface Complexation Model ◽  
Advantages And Disadvantages ◽  
The One

AbstractIn performance assessments, sorption of radionuclides dissolved in groundwater is mostly handled by the use of fixed Kd values. It has been well known that this approach is unsatisfying. Only during the last few years, however, tools have become available that make it possible to predict the actual Kd value in an aqueous solution that differs from the one in which the sorption properties were measured.One such approach is surface complexation (SC) that gives a detailed knowledge of the sorption properties. In SC, one tries to find what kinds of sorbed species are available on the surface and the thermodynamics for their formation from species in the bulk aqueous solution. Recently, a different approach, surface phase method (SP), has been developed. In SP, a thin layer including the surface is treated as a separate phase. In the bulk aqueous solution, the surface phase is treated as a virtual component, and from the chemical potential of this component, the sorption properties can be found.In the paper, we compare advantages and disadvantages of the two kinds of models. We also investigate the differences in predicted sorption properties of a number of radionuclides (Co, Np, Th and U). Furthermore, we discuss under which circumstances, one approach or the other is preferable.

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