Aji Aji - Academia.edu (original) (raw)
Papers by Aji Aji
This article was originally published in a journal published by Elsevier, and the attached copy i... more This article was originally published in a journal published by Elsevier, and the attached copy is provided by Elsevier for the author's benefit and for the benefit of the author's institution, for non-commercial research and educational use including without limitation use in instruction at your institution, sending it to specific colleagues that you know, and providing a copy to your institution's administrator. All other uses, reproduction and distribution, including without limitation commercial reprints, selling or licensing copies or access, or posting on open internet sites, your personal or institution's website or repository, are prohibited. For exceptions, permission may be sought for such use through Elsevier's permissions site at: http://www.elsevier.com/locate/permissionusematerial Abstract In this work, a statistical analysis of wind energy potential in Maiduguri is carried out, using Weibull distribution and 10 years (1995–2004) of wind data. The results show the Weibull distribution parameter C and K, the probability function T (V), the velocity frequency distribution f (V), the energy and power densities. The cost benefit analysis shows the economic feasibility of using wind energy conversion systems for electric power generation and supply in Maiduguri.
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Food Chemistry, 2010
... These results indicate that the aji-narezushi and kaburazushi are typical lactic acid-ferment... more ... These results indicate that the aji-narezushi and kaburazushi are typical lactic acid-fermented foods like other traditional sushi. ... In particular, there are many reports about manganese superoxide dismutase activity in LAB (Bruno-Bárcena, Andrus, Libby, Klaenhammer, & Hassan ...
Analytical Biochemistry, 1995
Recent developments in the application of stable isotopes and mass spectrometry have permitted th... more Recent developments in the application of stable isotopes and mass spectrometry have permitted the estimation of precursor enrichment and fractional synthesis of the product through mass isotopomer analysis. Thus, the application of isotopomer analysis in studies with 2H- and 13C-labeled glucose may potentially overcome the limitations of traditional methods which can only estimate the fractional use of carbon and hydrogen from glucose for lipogenesis. To illustrate this approach, isotope incorporation and mass isotopomer distribution were determined in fatty acids and cholesterol from a hepatoma cell line (Hep G2) grown in media containing specific (C1 or C6) 2H- or 13C-labeled glucose. Using the binomial model, the respective precursor enrichment, and fractional synthesis of palmitate, stearate and cholesterol were determined using mass isotopomer distribution analysis. In 1 week, 80% of palmitate, 65.5% of stearate, and 50% of cholesterol molecules in the cell extract were derived from de novo synthesis. Under serum-free condition, glucose contributed about 80% of the carbon of the newly synthesized lipids. Using the relative isotope yield of [1-13C] and [6-13C]glucose and a standard formula, the contribution of the pentose pathway to glucose catabolism was calculated to be 4.7%. Fractional syntheses of palmitate, stearate, and cholesterol determined using [1-2H]glucose agreed well with values determined using 13C-labeled glucose. After correcting for the contribution of deuterium label from the glycolytic pathway, the deuterium from [1-2H]glucose contributed 4.7% of the total reducing equivalents for lipogenesis. Unlike radioisotope studies, the stable isotope approach provides information from the perspective of the product and insight into the economy of acetyl units and reducing equivalents which were otherwise not available.
The phase diagram of the Cuprates is a collection of anomalies that has challenged our understand... more The phase diagram of the Cuprates is a collection of anomalies that has challenged our understanding of quantum many body physics. An organizing principle proposed to unify the experimental observations is the existence of a quantum critical point near optimal doping separating a phase which has broken time reversal and a renormalized Fermi liquid. I will discuss recent theoretical developments related to the nature of the fluctuations near the quantum critical point. The long wavelength theory of the time reversal violating state belongs to the dissipative 2DXY universality class. The fluctuation spectrum, at the quantum critical point, is local in space and power law in time, precisely of the form observed in the marginal fermi liquid phase near optimal doping. The fluctuations couple to the local angular momentum of the fermions to give a momentum dependence to the coupling which leads directly to pairing attraction in the d-wave channel. Theory of superconductivity in the cuprates, Vivek Aji, Arkady Shekhter and Chandra Varma, arXiv:0807.3741 Theory of the quantum critical fluctuations in cuprate superconductors, Vivek Aji and Chandra Varma, Physical Review Letters, 99, 067003 (2007)
Journal of Applied Polymer Science, 2006
The aim of this work has been to study the crystallization behavior of composites based on polyla... more The aim of this work has been to study the crystallization behavior of composites based on polylactic acid (PLA) and three different types of cellulose reinforcements, viz., microcrystalline cellulose (MCC), cellulose fibers (CFs), and wood flour (WF). The primary interest was to determine how the size, chemical composition, and the surface topography of cellulosic materials affect the crystallization of PLA. The studied composite materials were compounded using a twin-screw extruder and injection-molded to test samples. The content of cellulose reinforcements were 25% by weight. The MCC and WF were shown to have a better nucleating ability than CFs based on differential scanning calorimetry and optical microscopy studies. It is difficult to visualize that transcrystallization will occur during melting process and this process is influenced by the morphological and chemical characteristics of the reinforcement. Bulk crystallization seems to be mainly dependent on the processing temperature. The cold crystallization process was shown to improve the thermal stability and storage modulus of the composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 300–310, 2006
Physical Review B, 2009
In a recent paper [V. Aji and C.M. Varma, Phys. Rev. Lett. {\bf 99}, 167003 (2007) \cite{aji1}] w... more In a recent paper [V. Aji and C.M. Varma, Phys. Rev. Lett. {\bf 99}, 167003 (2007) \cite{aji1}] we have shown that the dissipation driven quantum phase transition of the 2D xy model represents a universality class where the correlations at criticality is local in space and power law in time. Here we provide a detailed analysis of the model. The local criticality is brought about by the decoupling of infrared singularities in space and time. The former leads to a Kosterlitz Thouless transition whereby the excitations of the transverse component of the velocity field (vortices) unbind in space. The latter on the other hand leads to a transition among excitations (warps) in the longitudinal component of the velocity field, which unbind in time. The quantum Ashkin-Teller model, with which the observed loop order in the Cuprates is described maps in the critical regime to the quantum xy model. We also discuss other models which are expected to have similar properties.
Journal of Mineralogical and Petrological Sciences, 2004
... fades. The former gives a Rb-Sr whole-rock isochron age of 82.9±8.0 Ma with Sri of 0.70773 ±0... more ... fades. The former gives a Rb-Sr whole-rock isochron age of 82.9±8.0 Ma with Sri of 0.70773 ±0.00007 which is interpreted as the intrusive age of the Aji Granite and therefore the final plutonism in the eastern Sanuki district. ...
Euphytica, 2009
Ají (Capsicum baccatum L.) and rocoto (C. pubescens R. & P.) are two Capsicum pepper species nati... more Ají (Capsicum baccatum L.) and rocoto (C. pubescens R. & P.) are two Capsicum pepper species native to the Andean region that have not been subjected to intensive breeding. However, the increase in its demand in European markets has sparked the development of breeding programmes for adaptation to Mediterranean climates, which include breeding for higher levels of bioactive compounds. We have studied the composition of red and yellow carotenoids (C R and C Y, respectively), ascorbic acid (AA), and total phenolics (TP) in 34 accessions of Capsicum, including 23 of C. baccatum, eight of C. pubescens, and 3 controls of C. annuum, which were grown in Spain both under greenhouse (GH) and open field (OF) conditions. The results show that in both growing conditions C. baccatum presents a considerable variation for most of the traits studied, with several accessions having similar or higher levels than C. annuum for the compounds studied. This indicates that C. baccatum is an important source of antioxidant compounds with nutritional value. On the contrary, C. pubescens had a poor performance, with low levels for all the compounds studied, and a poor adaptation to the conditions of Mediterranean climates. When considering the GH or OF growing cycles separately, heritability values were high (>0.75) for C R, C Y and AA, and moderate (0.42 for GH and 0.62 for OF) for TP. The existence of an important genotype × environment interaction resulted in lower levels for heritability when considering both growing cycles together, although the values were still high for C R and AA (>0.6). Positive significant genotypic correlations among all the traits studied were found, except for TP with C R and AA in the OF cycle. This information indicates that there are good prospects for developing C. baccatum varieties with higher levels of bioactive compounds.
... I love Joseph Roth's Radetsky March. ... Some performance is very sloppy and... more ... I love Joseph Roth's Radetsky March. ... Some performance is very sloppy and too easy. But yes, I think the most interesting poetry being written today is very aware of performancefor example, that of Christian Bök or Kenneth Goldsmith, Caroline Bergvall, Tracie Morris. ...
Cellulose, 2006
The objective of this work was to find a rapid, high-yield process to obtain an aqueous stable co... more The objective of this work was to find a rapid, high-yield process to obtain an aqueous stable colloid suspension of cellulose nanocrystals/whiskers. Large quantities are required since these whiskers are designed to be extruded into polymers in the production of nano-biocomposites. Microcrystalline cellulose (MCC), derived from Norway spruce (Picea abies), was used as the starting material. The processing parameters have been optimized by using response surface methodology. The factors that varied during the process were the concentration of MCC and sulfuric acid, the hydrolysis time and temperature, and the ultrasonic treatment time. Responses measured were the median size of the cellulose particles/whiskers and yield. The surface charge as calculated from conductometric titration, microscopic examinations (optical and transmission electron microscopy), and observation of birefringence were also investigated in order to determine the outcome (efficiency) of the process. With a sulfuric acid concentration of 63.5% (w/w), it was possible to obtain cellulose nanocrystals/whiskers with a length between 200 and 400 nm and a width less than 10 nm in approximately 2 h with a yield of 30% (of initial weight).
This article was originally published in a journal published by Elsevier, and the attached copy i... more This article was originally published in a journal published by Elsevier, and the attached copy is provided by Elsevier for the author's benefit and for the benefit of the author's institution, for non-commercial research and educational use including without limitation use in instruction at your institution, sending it to specific colleagues that you know, and providing a copy to your institution's administrator. All other uses, reproduction and distribution, including without limitation commercial reprints, selling or licensing copies or access, or posting on open internet sites, your personal or institution's website or repository, are prohibited. For exceptions, permission may be sought for such use through Elsevier's permissions site at: http://www.elsevier.com/locate/permissionusematerial Abstract In this work, a statistical analysis of wind energy potential in Maiduguri is carried out, using Weibull distribution and 10 years (1995–2004) of wind data. The results show the Weibull distribution parameter C and K, the probability function T (V), the velocity frequency distribution f (V), the energy and power densities. The cost benefit analysis shows the economic feasibility of using wind energy conversion systems for electric power generation and supply in Maiduguri.
Step to change background
Food Chemistry, 2010
... These results indicate that the aji-narezushi and kaburazushi are typical lactic acid-ferment... more ... These results indicate that the aji-narezushi and kaburazushi are typical lactic acid-fermented foods like other traditional sushi. ... In particular, there are many reports about manganese superoxide dismutase activity in LAB (Bruno-Bárcena, Andrus, Libby, Klaenhammer, & Hassan ...
Analytical Biochemistry, 1995
Recent developments in the application of stable isotopes and mass spectrometry have permitted th... more Recent developments in the application of stable isotopes and mass spectrometry have permitted the estimation of precursor enrichment and fractional synthesis of the product through mass isotopomer analysis. Thus, the application of isotopomer analysis in studies with 2H- and 13C-labeled glucose may potentially overcome the limitations of traditional methods which can only estimate the fractional use of carbon and hydrogen from glucose for lipogenesis. To illustrate this approach, isotope incorporation and mass isotopomer distribution were determined in fatty acids and cholesterol from a hepatoma cell line (Hep G2) grown in media containing specific (C1 or C6) 2H- or 13C-labeled glucose. Using the binomial model, the respective precursor enrichment, and fractional synthesis of palmitate, stearate and cholesterol were determined using mass isotopomer distribution analysis. In 1 week, 80% of palmitate, 65.5% of stearate, and 50% of cholesterol molecules in the cell extract were derived from de novo synthesis. Under serum-free condition, glucose contributed about 80% of the carbon of the newly synthesized lipids. Using the relative isotope yield of [1-13C] and [6-13C]glucose and a standard formula, the contribution of the pentose pathway to glucose catabolism was calculated to be 4.7%. Fractional syntheses of palmitate, stearate, and cholesterol determined using [1-2H]glucose agreed well with values determined using 13C-labeled glucose. After correcting for the contribution of deuterium label from the glycolytic pathway, the deuterium from [1-2H]glucose contributed 4.7% of the total reducing equivalents for lipogenesis. Unlike radioisotope studies, the stable isotope approach provides information from the perspective of the product and insight into the economy of acetyl units and reducing equivalents which were otherwise not available.
The phase diagram of the Cuprates is a collection of anomalies that has challenged our understand... more The phase diagram of the Cuprates is a collection of anomalies that has challenged our understanding of quantum many body physics. An organizing principle proposed to unify the experimental observations is the existence of a quantum critical point near optimal doping separating a phase which has broken time reversal and a renormalized Fermi liquid. I will discuss recent theoretical developments related to the nature of the fluctuations near the quantum critical point. The long wavelength theory of the time reversal violating state belongs to the dissipative 2DXY universality class. The fluctuation spectrum, at the quantum critical point, is local in space and power law in time, precisely of the form observed in the marginal fermi liquid phase near optimal doping. The fluctuations couple to the local angular momentum of the fermions to give a momentum dependence to the coupling which leads directly to pairing attraction in the d-wave channel. Theory of superconductivity in the cuprates, Vivek Aji, Arkady Shekhter and Chandra Varma, arXiv:0807.3741 Theory of the quantum critical fluctuations in cuprate superconductors, Vivek Aji and Chandra Varma, Physical Review Letters, 99, 067003 (2007)
Journal of Applied Polymer Science, 2006
The aim of this work has been to study the crystallization behavior of composites based on polyla... more The aim of this work has been to study the crystallization behavior of composites based on polylactic acid (PLA) and three different types of cellulose reinforcements, viz., microcrystalline cellulose (MCC), cellulose fibers (CFs), and wood flour (WF). The primary interest was to determine how the size, chemical composition, and the surface topography of cellulosic materials affect the crystallization of PLA. The studied composite materials were compounded using a twin-screw extruder and injection-molded to test samples. The content of cellulose reinforcements were 25% by weight. The MCC and WF were shown to have a better nucleating ability than CFs based on differential scanning calorimetry and optical microscopy studies. It is difficult to visualize that transcrystallization will occur during melting process and this process is influenced by the morphological and chemical characteristics of the reinforcement. Bulk crystallization seems to be mainly dependent on the processing temperature. The cold crystallization process was shown to improve the thermal stability and storage modulus of the composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 300–310, 2006
Physical Review B, 2009
In a recent paper [V. Aji and C.M. Varma, Phys. Rev. Lett. {\bf 99}, 167003 (2007) \cite{aji1}] w... more In a recent paper [V. Aji and C.M. Varma, Phys. Rev. Lett. {\bf 99}, 167003 (2007) \cite{aji1}] we have shown that the dissipation driven quantum phase transition of the 2D xy model represents a universality class where the correlations at criticality is local in space and power law in time. Here we provide a detailed analysis of the model. The local criticality is brought about by the decoupling of infrared singularities in space and time. The former leads to a Kosterlitz Thouless transition whereby the excitations of the transverse component of the velocity field (vortices) unbind in space. The latter on the other hand leads to a transition among excitations (warps) in the longitudinal component of the velocity field, which unbind in time. The quantum Ashkin-Teller model, with which the observed loop order in the Cuprates is described maps in the critical regime to the quantum xy model. We also discuss other models which are expected to have similar properties.
Journal of Mineralogical and Petrological Sciences, 2004
... fades. The former gives a Rb-Sr whole-rock isochron age of 82.9±8.0 Ma with Sri of 0.70773 ±0... more ... fades. The former gives a Rb-Sr whole-rock isochron age of 82.9±8.0 Ma with Sri of 0.70773 ±0.00007 which is interpreted as the intrusive age of the Aji Granite and therefore the final plutonism in the eastern Sanuki district. ...
Euphytica, 2009
Ají (Capsicum baccatum L.) and rocoto (C. pubescens R. & P.) are two Capsicum pepper species nati... more Ají (Capsicum baccatum L.) and rocoto (C. pubescens R. & P.) are two Capsicum pepper species native to the Andean region that have not been subjected to intensive breeding. However, the increase in its demand in European markets has sparked the development of breeding programmes for adaptation to Mediterranean climates, which include breeding for higher levels of bioactive compounds. We have studied the composition of red and yellow carotenoids (C R and C Y, respectively), ascorbic acid (AA), and total phenolics (TP) in 34 accessions of Capsicum, including 23 of C. baccatum, eight of C. pubescens, and 3 controls of C. annuum, which were grown in Spain both under greenhouse (GH) and open field (OF) conditions. The results show that in both growing conditions C. baccatum presents a considerable variation for most of the traits studied, with several accessions having similar or higher levels than C. annuum for the compounds studied. This indicates that C. baccatum is an important source of antioxidant compounds with nutritional value. On the contrary, C. pubescens had a poor performance, with low levels for all the compounds studied, and a poor adaptation to the conditions of Mediterranean climates. When considering the GH or OF growing cycles separately, heritability values were high (>0.75) for C R, C Y and AA, and moderate (0.42 for GH and 0.62 for OF) for TP. The existence of an important genotype × environment interaction resulted in lower levels for heritability when considering both growing cycles together, although the values were still high for C R and AA (>0.6). Positive significant genotypic correlations among all the traits studied were found, except for TP with C R and AA in the OF cycle. This information indicates that there are good prospects for developing C. baccatum varieties with higher levels of bioactive compounds.
... I love Joseph Roth's Radetsky March. ... Some performance is very sloppy and... more ... I love Joseph Roth's Radetsky March. ... Some performance is very sloppy and too easy. But yes, I think the most interesting poetry being written today is very aware of performancefor example, that of Christian Bök or Kenneth Goldsmith, Caroline Bergvall, Tracie Morris. ...
Cellulose, 2006
The objective of this work was to find a rapid, high-yield process to obtain an aqueous stable co... more The objective of this work was to find a rapid, high-yield process to obtain an aqueous stable colloid suspension of cellulose nanocrystals/whiskers. Large quantities are required since these whiskers are designed to be extruded into polymers in the production of nano-biocomposites. Microcrystalline cellulose (MCC), derived from Norway spruce (Picea abies), was used as the starting material. The processing parameters have been optimized by using response surface methodology. The factors that varied during the process were the concentration of MCC and sulfuric acid, the hydrolysis time and temperature, and the ultrasonic treatment time. Responses measured were the median size of the cellulose particles/whiskers and yield. The surface charge as calculated from conductometric titration, microscopic examinations (optical and transmission electron microscopy), and observation of birefringence were also investigated in order to determine the outcome (efficiency) of the process. With a sulfuric acid concentration of 63.5% (w/w), it was possible to obtain cellulose nanocrystals/whiskers with a length between 200 and 400 nm and a width less than 10 nm in approximately 2 h with a yield of 30% (of initial weight).