262 research outputs found
Kinetics of invertase synthesis by Saccharomyces cerevisiae in synthetic medium
Present investigation deals with optimization of appropriate substrate concentration and incubation temperature both for growth of Saccharomyces cerevisiae and invertase production. Submerged fermentation technique was employed in the present study. The maximal production of invertase during the course of study was achieved after 48 h of incubation using initial sucrose concentration, 15.0 g l-1. The sugar consumption and dry cell mass were also examined. Data was subjected to kinetic analysis and on the basis of kinetic parameters such as Yp/x (amount of enzyme produced mg-1 cell mass), Yp/s (amount of enzyme produced mg-1 sugar consumed), Yx/s (mg cells mg-1 substrate consumed), Ys/x (mg sugar consumed mg-1 cell mass produced), qp (Amount of enzyme produced mg-1 sugar consumed h-1), qs (mg mg-1 cells h-1), qx (mg cells mg-1 sugar consumed h-1), µ (mg cells produced h-1), it was found that temperature had a direct influence both on substrate consumption and synthesis of enzyme. Similarly, higher concentrations of sucrose in fermentation medium induced catabolite repression of yeast invertase
Evaluation of Research Productivity of the Islamia University of Bahawalpur, Pakistan
The aim of this paper is to evaluate the research output and publications trends of the Islamia University of Bahawalpur (IUB), Pakistan for the last 42 years as observed in the Scopus database. IUB is the premier degree-awarding institution of the Southern Punjab, Pakistan and considerably subsidized their valuable share in national research growth. A quantitative bibliometric research technique was employed to enumerate the documents and their parameters. The publications record of IUB from 1980 to 2021 was retrieved on 2nd January 2022. The Microsoft Excel and VOSviewer software were used to appraise the dataset and presented the findings in tabular/graphic formats. The authors affiliated to IUB contributed the share of 2.52% in the national research growth of Pakistan with 6,209 documents and 62% of the documents were published in the last five years (2017-2021). The review papers and subscription-based documents gained more citations as compared to articles and open-accessed documents. The highest numbers of the documents were published on the subject area of “Agricultural and Biological Sciences” and about 15% of the documents were published in top-10 journals. Bahauddin Zakariya University was found on the top among the research collaborative institutions and China emerged as the top preference in the international research collaboration. The findings confirmed that a promising research growth has been explicit in the last decade. The outcomes of this study are significant for the IUB authorities and they can review their efforts to promote research culture. The findings of this paper would also serve as a benchmark for the future studies on IUB as well as the other universities of Pakistan
Callus proliferation and somatic embryogenesis in cotton (Gossypium hirsutum L.)
Somatic embryogenesis and plant regeneration are fundamental to tissue culture biotechnology in cotton (Gossypium hirsutum L.) cv. Coker 312. Callus proliferation was considered best on MS1a (2.0 mg/L NAA; 0.1 mg/L ZT; 0.1 mg/L KT) when 6 weeks old callus was cultured from MS1b (0.1 mg/L 2, 4-D; 0.5 mg/L KT)medium, there is no need to select embryogenic calli for somatic embryogenesis, as all of them were converted to somatic embryos. NH4NO3 play an important role in differentiation of callus into somatic embryos but is lethal for embryos just after two weeks. However, KNO3 is less efficient for somatic embryo induction but is best for embryo maturation. By this procedure 56.51% cotyledenary embryos were developed within 5 weeks. Of that, 82.05% cotyledenary embryos were developed not only into normal plantlets, but rooted simultaneously when cultured on MS (with 0.05 mg/L GA3) medium. A complete plant of Cocker-312 could be regenerated through somatic embryogenesis within 4 to 5 months.African Journal of Biotechnology Vol. 4 (2), pp. 206-209, 200
Bio-Bibliometric Portrait of Dr. Tasawar Hayat, Distinguished Professor of Mathematics
Aim: This article aims to present the bio-bibliometric portrait of the research productivity created by Dr. Tasawar Hayat, a Distinguished Professor of Mathematics at Quaid-e-Azam University, Pakistan.
Methodology: The retrospective method has been applied in this study to assess the attributes of bibliographical records of the documents produced by Dr. Hayat. Elsevier’s Scopus database was used to extract the required dataset on the 28th of October 2020. The required features of the dataset of all types of published papers were downloaded for analysis. The five bibliometric indicators of the dataset were evaluated, the publications and citations ratio by year, segregation of documents by subjects, frequently used channels for publications, distribution of research collaboration by country and top-ranked co-authors. Microsoft Excel was used for the tabulated pattern and graphic interpretation, and SPSS software was used to calculate the SEM of publications and citations.
Results: A total of 2,374 documents were found on the credit of Dr. Hayat on the data freezing date. Although there has been a fluctuation in the number of papers by year, overall there is a remarkable growth. The impact of quality is reflected by the number of citations that recorded 29.28 citations/doc. In the subject categories, Physics & Astronomy, Engineering and Mathematics were found the favorite areas of research. Results in Physics and Journal of Molecular Liquids are listed in top the two most preferred channels of communication having the impact factor 4.019 and 5.065 with 119 and 105 publications respectively. Pakistan has been on the first ranked in the affiliated country statement of Dr. Hayat and his co-author, followed by Saudi Arabia (n=1921), China (n=704), United States (n=106) and United Kingdom (n=96). Dr. Ahmed Alsaedi of King Abdulaziz University, Saudi Arabia has emerged a strong co-author in more than half of the documents (n=1324; 55.77%).
Conclusion: The author with fertile ideas and a creative mindset provide a strong foundation to his profession and affiliated institution. The bio-bibliometric study of the productive scientist encourages the peers and junior to follow in his footsteps. Behind the massive research success of Dr. Hayat, along with his hard work and dedication, the contribution of his co-author is also mattered. But Dr. Hayat has been playing the role of captain for his research team
Social Sciences Research in Pakistan; Bibliometric Analysis
Aim. The study aimed to explore the progress of social science research carried out by Pakistan for the duration of 59 years.
Method: This retrospective study was carried out on the data retrieved from the Scopus database to determine the research output in the area of social science by Pakistani authors from 1961 to December 2019. The word “Pakistan” has been written in the main search box and “Affiliation” has been selected in the subsequent box. The targeted time duration was selected, further, the social sciences documents were selected and downloaded for data-analysis. Microsoft Excel spreadsheet and SPSS were used to calculate and analyze the data.
Result: Pakistani author wrote 9,292 papers on social sciences with an average of 157.49 papers per year, three-fourth of the papers were published in the last ten years of study. These publications received 56,252 citations with an average of 6.05 citations per paper. One-fourth of the total documents were published in the ten most preferred journals and Pakistan Development Review has been on the top with 1067 documents. The Scopus further divided these documents into 24 sub-categories, computer sciences found a most favorite area followed by art and humanities. Pakistani authors collaborated with 134 countries of the world, the United States has a topmost choice for international research collaboration. In the analysis of the authorship pattern, the single author pattern dominated.
Conclusion: The establishment of new universities and up-gradation of the social sciences departments, provision of national digital library and starting of doctorate programs are the key factors of promising growth of publications was found during the last ten years of study. Still, we need to do more innovative research with the corporate sector for the betterment of the society
An investigation of the creep characteristics of Portland cement mortar under static and dynamic strain
The combined effect of static and dynamic loads on design of underground openings is currently receiving much attention. It is known that the time-dependent behavior of rock is considerably different when a dynamic load is superimposed on prestressed rock. The shape of an underground opening has a definite influence on the magnitude of the local stresses and these may be significantly larger than those due to the weight of the overlying rock alone. Under these conditions, even a small dynamic load in the form of vibrations caused by blasting, drilling and related operations may increase the stress beyond a critical value. Dynamic tests in the laboratory are much more involved than static tests, and it is very useful to determine the relationships that exist between the static and dynamic creep.
This dissertation presents the results of an investigation of the creep behavior of mortar under simultaneous static and dynamic stress. Two types of dynamic loads were applied in the form of a cyclic stress of low frequency: (1) an excitation load and (2) a cyclic load linearly additive to the static load.
Based on the static creep behavior of mortar, a mathematical analysis for the dynamic loading conditions is presented. A comparison is made between the experimental results and the mathematical predictions. Finally a mathematical model is presented which best fits the dynamic creep behavior of mortar --Abstract, page ii
Some dynamic creep characteristics of gypsum
A review of literature concerned with time-dependent deformation of geologic and non-geologic materials is presented. A static loading machine and a four unit dynamic loading unit was designed and assembled to evaluate static and dynamic creep properties of gypsum. The tests were run for various levels of static loads, and superimposed dynamic loads. Investigations were carried out to determine the relationships, if any, between impact energy, impact velocity and momentum, and dynamic strains. Viscoelastic coefficients were determined for the investigations. The conclusion was presented that time-dependent strain in the dynamic creep tests of the particular gypsum rock tested is a function of impact momentum within the elastic limit of the material --Abstract, page ii
Stock Market Efficiency and Size of the Firm: Empirical Evidence from Pakistan
The purpose of this paper is to examine the relationship between firm size and excess stock returns in Pakistani market. We construct a set of 10 portfolios based on size i.e., market capitalization, total assets and sales for the period between 2007 and 2011, and analyze the annual stock returns by using sorting and Fama & Macbeth model. The results of the study indicate a prominent size effect where smaller firm or size portfolios are found to have a greater average annual excess returns than bigger firm or size portfolios during the period under analysis. We find that small firms have significantly greater excess returns than larger firms. The study has strong implications for mutual funds managers, investment analysts as well as small investors who are continuously at a lookout for the trading strategies that beat the market
Carbon-driven Chemical Interactions between Alumina and Iron: A possible reaction pathway in Earth's interior
Seismological and geochemical observations have revealed a complex structure for the earth's core-mantle boundary (CMB) region, with lateral and chemical heterogeneities. The presence of higher than expected concentrations of siderophile elements (Ni, Co, Pt etc) in the earth's mantle, iron enrichment of the lower mantle relative to the upper mantle, and a possible carbon flux from the core suggest the possibility of continual long-term exchange of materials between the core and the mantle. The chemical interactions of molten iron with complex mantle oxides and diffusion have been postulated as key mechanisms. A number of studies have been carried out on the reduction reactions taking into account the extreme conditions of high-temperature and high-pressure in earth's interior. These studies have, however, neglected to consider the influence of carbon on these reactions. The earth's metallic core is rich in carbon (~ 5 wt% C), and there is a growing evidence for the presence of carbon in the earth's mantle as well. Carbon can affect redox conditions through chemical interactions with oxygen, and is a critical element in determining the oxidation state of siderophile elements. Here we present a study of the interactions between liquid iron and alumina-carbon substrates at 1,823K in argon atmosphere, and report on the formation of a Fe-Al~0.25-0.5~ alloy at ambient pressure. Iron induced reduction of alumina in the absence of carbon, has been previously reported to occur only at pressures above 60 GPa and temperatures of 2,200K. Our results demonstrate that carbon enriched iron is capable of reducing alumina in regions of much lower pressures. These chemical reactions could provide an important mechanism for the reduction reactions occurring in earth's interior, and be responsible for far higher levels of heterogeneities than currently believed
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