Shama Parveen - Academia.edu (original) (raw)
Papers by Shama Parveen
Current Topics in Chikungunya, 2016
Dengue and Chikungunya fever are the arboviral infections that are endemic in tropical and subtro... more Dengue and Chikungunya fever are the arboviral infections that are endemic in tropical and subtropical regions. These two viral infections share common clinical symptoms. These infections are transmitted by a common mosquito vector so these viruses co-circulate in many geographical regions. Various clinical investigations, particularly from India and African countries have documented the dual infection with these viruses. However, the true disease burden of Dengue and Chikungunya dual viral infections is still not known because most of these studies involved a smaller patient group. Therefore, in depth investigations involving larger patient groups are needed to examine the complete pathogenicity and severity of the dual viral infections. The timely diagnosis of the pathogens and correlation of disease severity with mono or dual infections is essential for effective patient management. In addition, the detailed molecular and cellular mechanism of co-infection should be investigated to describe a complete picture of the interaction of two viral pathogens in the host cell. Further comprehensive studies of dual infections from the endemic regions will determine the epidemiological and evolutionary pattern of these emerging viruses. This data will also assist in designing and implementation of effective control measures.
PLoS neglected tropical diseases, 2016
Dengue fever is the most important arboviral disease in the tropical and sub-tropical countries o... more Dengue fever is the most important arboviral disease in the tropical and sub-tropical countries of the world. Delhi, the metropolitan capital state of India, has reported many dengue outbreaks, with the last outbreak occurring in 2013. We have recently reported predominance of dengue virus serotype 2 during 2011-2014 in Delhi. In the present study, we report molecular characterization and evolutionary analysis of dengue serotype 2 viruses which were detected in 2011-2014 in Delhi. Envelope genes of 42 DENV-2 strains were sequenced in the study. All DENV-2 strains grouped within the Cosmopolitan genotype and further clustered into three lineages; Lineage I, II and III. Lineage III replaced lineage I during dengue fever outbreak of 2013. Further, a novel mutation Thr404Ile was detected in the stem region of the envelope protein of a single DENV-2 strain in 2014. Nucleotide substitution rate and time to the most recent common ancestor were determined by molecular clock analysis using B...
Pathogens and disease, Jan 10, 2015
The Chikungunya virus is a re-emerging alphavirus that belongs to family Togaviridae. The symptom... more The Chikungunya virus is a re-emerging alphavirus that belongs to family Togaviridae. The symptoms include fever, rashes, nausea and joint pain that may last for months. The laboratory diagnosis of the infection is based on the serologic assays, virus isolation and molecular methods. The pathogenesis of the Chikungunya viral infection is not completely understood. Some of the recent investigations have provided information on replication of the virus in various cells and organs. In addition, some recent reports have indicated that the severity of disease is correlated with the viral load and cytokines.The Chikungunya virus infection re-emerged as an explosive epidemic during 2004-09 affecting millions of people in the Indian Ocean. Subsequent global attention was given to research on this viral pathogen due to its broad area of geographical distribution during this epidemic. Chikungunya viral infection has become a challenge for the public health system because of absence of a vacci...
PLOS ONE, 2015
Dengue fever is the most prevalent arboviral disease in the tropical and subtropical regions of t... more Dengue fever is the most prevalent arboviral disease in the tropical and subtropical regions of the world. The present report describes molecular detection and serotyping of dengue viruses in acute phase blood samples collected from New Delhi, India. Phylogenetic and molecular clock analysis of dengue virus serotype 1 and 3 strains were also investigated. Dengue virus infection was detected in 68.87% out of 604 samples tested by RT-PCR between 2011 & 2014. Dengue serotype 1 was detected in 25.48% samples, dengue serotype 2 in 79.56% samples and dengue serotype 3 in 11.29% samples. Dengue serotype 4 was not detected. Co-infection by more than one dengue serotype was detected in 18.26% samples. Envelope gene of 29 DENV-1 and 14 DENV-3 strains were sequenced in the study. All the DENV-1 strains grouped with the American African genotype. All DENV-3 strains were found to belong to Genotype III. Nucleotide substitution rates of dengue 1 and 3 viruses were determined in the study. Time to the most recent common ancestor (TMRCA) of dengue 1 viruses was determined to be 132 years. TMRCA of DENV-3 viruses was estimated to be 149 years. Bayesian skyline plots were constructed for Indian DENV-1 and 3 strains which showed a decrease in population size since 2005 in case of DENV-1 strains while no change was observed in recent years in case of DENV-3 strains. The study also revealed a change in the dominating serotype in Delhi, India in recent years. The study will be helpful in formulating control strategies for the outbreaks. In addition, it will also assist in tracking the movement and evolution of this emerging virus.
VirusDisease, 2015
Human respiratory syncytial virus (hRSV) is the most common viral pathogen of acute lower respira... more Human respiratory syncytial virus (hRSV) is the most common viral pathogen of acute lower respiratory tract infection in infants and young children. The G protein of hRSV is the trans-membrane glycoprotein that is involved in the attachment of virion with the host cell. The nasopharyngeal aspirates were subjected to RT-PCR for the second hypervariable region of the G protein gene in the present investigation. Sequencing and phylogenetic analysis revealed that all the study strains clustered within the BA genotype. The study sequences further clustered in BA-9, BA-7, BA-10 and BA-12 subgroups within the BA genotype. The G proteins of the study sequences were predicted to encode 312 and 319 amino acids. Three different N-linked glycosylation sites were observed in the deduced 93-100 amino acid region. There were 40-43 serine and threonine residues that are the potential O-linked glycosylation sites. The non-synonymous/synonymous (dN/dS) ratio was less than one indicating negative selection pressure for amino acid change in the analyzed region of the G protein. The present investigation provides information on circulating strains of BA genotype from New Delhi, India. Further elaborate investigations of the BA viruses from different regions of the world will establish the basis of the rapid global spread and evolutionary pattern of this expanding genotype. Keywords BA genotype Á G protein gene Á Human respiratory syncytial virus Á Phylogenetic analysis VLN Raghuram S and Wajihul Hasan Khan have contributed equally to this work.
Preparative biochemistry & biotechnology, Jan 7, 2015
Human respiratory syncytial virus (hRSV) is an important pathogen of acute respiratory tract infe... more Human respiratory syncytial virus (hRSV) is an important pathogen of acute respiratory tract infection. The human respiratory syncytial virus (hRSV) expresses major surface transmembrane glycoproteins, F and G. The G protein of hRSV is a neutralizing antigen and is thus a vaccine candidate. The G protein of hRSV consists of three functional domains, namely N-terminal cytoplasmic region, attachment region and ectodomain region. In the present study, ectodomain G protein, G(▵TM) was cloned and expressed in prokaryotic system. The codon optimized ectodomain G protein gene of BA genotype of group B hRSV strain was amplified from synthetic gene. The amplified fragment was cloned into pGEMT-easy vector and subcloned into pET-28a vector. The protein was expressed in BL21-AI cells. The G(▵TM) was purified with Ni-NTA column. The purified protein was used for biophysical characterization, including circular dichroism, as well as thermal and chemical denaturation. The molar absorption co-effi...
In the present work, braided composite rods (BCRs) have been developed through braiding of polypr... more In the present work, braided composite rods (BCRs) have been developed through braiding of polypropylene (PP) fibres around an axially oriented core, made of a mixture of PP and sisal fibres and subsequent consolidation of the produced structures under heat and pressure. Tensile properties of these BCRs were characterized. The effect of alkali treatment of sisal fibres on their surface morphology as well as mechanical properties of sisal fibres and produced BCRs was thoroughly investigated. It was observed that the tensile properties of developed BCRs improved strongly with the increase in sisal fibre vol.% and moreover, the alkali treatment improved the tensile properties of sisal fibre and their interfacial interactions with PP matrix, leading to enhanced tensile behaviour of BCRs.
Carbon nanotubes (CNTs) are finding widespread applications in various fields including catalyst ... more Carbon nanotubes (CNTs) are finding widespread applications in various fields including catalyst supports, optical devices, quantum computers, and biomedical field due to their unique electronic, thermal, optical, and mechanical properties [1, 2]. Most of these applications require stable suspensions of high concentration of CNTs. The non-covalent functionalization technique of producing CNT suspensions is better in the sense that it does not alter the inherent electrical, optical or mechanical properties of CNT. In this route, CNTs are commonly dispersed using various surfactants, such as etyltrimethylammonium bromide, Triton X-100, sodium dodecylbenzene sulfonate (SDBS), Pluronic F127, etc. [3], with the help of ultrasonication process, which breaks down or de-bundles the CNT aggregates. The treatment time or energy of the ultrasonication process has strong influence on CNT dispersion and within limits, longer is the treatment time (and higher is the ultrasonication energy), better is the CNT dispersion. However, a longer ultrasonication treatment or higher ultrasonication energy may also reduce the aspect ratio and lead to CNT damage. From this point of view, a short and mild dispersion process is always favourable. On the other hand, among the various surfactants, currently Pluronics are finding a special attention due to its biocompatibility and lower toxicity as compared to other surfactants [4]. However, only limited number of research studies has been carried out till date on the aqueous dispersion of CNT using Pluronic, especially at high concentrations.
ISRN Nanomaterials, 2012
We observe hysteresis in J-E plot during field emission measurement of CNTs grown by LPCVD techni... more We observe hysteresis in J-E plot during field emission measurement of CNTs grown by LPCVD technique. CNTs are synthesized on Fe-coated Si substrate at 650°C. SEM and Raman study confirm that CNTs are successfully grown on Si substrate by LPCVD technique. In this study, we find that ramp-down curve has higher value of current density than ramp-up curve which indicates that CNTs show positive hysteresis. Our results show that a high current density at low turn-on voltage is obtained in ramp-down step of J-E plot which may be since not all CNTs contribute in ramp-up step process. But in ramp-down step all CNTs contribute as field emitters due to high electric field treatment. We also performed stability analysis of CNTs with current at constant applied voltage for 5 hrs and find that the sample shows long-term stability due to increase in emitting site density since a large number of CNTs participate in field emission.
Environmental Science and Engineering, 2013
In this work, ultra long vertically aligned single wall carbon nanotubes are synthesised by Plasm... more In this work, ultra long vertically aligned single wall carbon nanotubes are synthesised by Plasma enhanced chemical vapour deposition (PECVD) technique at 600 °C temperature. The presence of built-in electric field in a plasma sheath aligns the growing CNTs along the field lines. Also, PECVD method favours low temperature synthesis of VA-SWCNTs. SEM and Raman are used to characterized as grown sample. Enhanced Field emission properties of as-grown VA-SWCNTs are also studied.
Journal of Nanomaterials, 2013
Excellent mechanical, thermal, and electrical properties of carbon nanotubes (CNTs) and nanofiber... more Excellent mechanical, thermal, and electrical properties of carbon nanotubes (CNTs) and nanofibers (CNFs) have motivated the development of advanced nanocomposites with outstanding and multifunctional properties. After achieving a considerable success in utilizing these unique materials in various polymeric matrices, recently tremendous interest is also being noticed on developing CNT and CNF reinforced cement-based composites. However, the problems related to nanomaterial dispersion also exist in case of cementitious composites, impairing successful transfer of nanomaterials' properties into the composites. Performance of cementitious composites also depends on their microstructure which is again strongly influenced by the presence of nanomaterials. In this context, the present paper reports a critical review of recent literature on the various strategies for dispersing CNTs and CNFs within cementitious matrices and the microstructure and mechanical properties of resulting nano...
Textile Science and Clothing Technology, 2014
This chapter discusses the present scenario and market trend of some important natural plant fibe... more This chapter discusses the present scenario and market trend of some important natural plant fibers such as cotton, flax, jute, and hemp. Production, processing, and applications of these fibers are discussed. The factors influencing the sustainability of these natural plant fibers are presented and various lifecycle assessment studies performed on these fibers to evaluate their environmental impacts and sustainability are discussed.
Textile Science and Clothing Technology, 2014
ABSTRACT This chapter discusses the present scenario and market trend of regenerated cellulosic f... more ABSTRACT This chapter discusses the present scenario and market trend of regenerated cellulosic fibers, and the properties of principal fibers existing in the market as well as some new fibers recently developed and yet to be explored. Production technologies of these fibers are discussed and their potential applications are presented. Various sustainability issues related to the production of regenerated cellulosic fibers are dealt within this chapter. The last section discusses the results of research studies conducted to assess the environmental impacts and sustainability aspects of regenerated cellulose fibers.
Transition Metal Chemistry, 2006
... Mohammad Shakir*, Shakira Khatoon, Shama Parveen and Yasser Azim Division of Inorganic Chemis... more ... Mohammad Shakir*, Shakira Khatoon, Shama Parveen and Yasser Azim Division of Inorganic Chemistry, Department of Chemistry, Aligarh Muslim University, Aligarh 202002 ... of the metal free ligand, L confirms the proposed formula by showing a peak at m/z 773 corresponding ...
2(H2O)2.25](https://attachments.academia-assets.com/118114119/thumbnails/1.jpg)
](Transition Metal Chemistry, 2004
Complexes of the type [M(tren)(abpt)](NO 3) 2 (H 2 O) n (1-6) [M ¼ Mn II , Fe II , Co II , Cu II ... more Complexes of the type [M(tren)(abpt)](NO 3) 2 (H 2 O) n (1-6) [M ¼ Mn II , Fe II , Co II , Cu II , Zn II (n ¼ 2), Ni II (n ¼ 2.25), tren ¼ tris(2-aminoethyl)amine, and abpt ¼ 4-amino-3,5-bis(pyridin-2yl)-1,2,4 triazole] have been prepared. The bonding mode and overall geometry of the complexes have been deduced by elemental analyses, molar conductance values, spectral studies (obtained from FT-IR), 1 H-n.m.r., electronic spectral analyses and magnetic susceptibility measurements. A detailed molecular structure of complex (4) has been determined by single X-ray crystallography.
![Research paper thumbnail of Metal Ion Promoted Synthesis of Hexaaza[17]paracyclophane Derived from Terephthalaldehyde Involving Co(II), Ni(II), Cu(II), and Zn(II) and Their Physico‐chemical Properties](https://attachments.academia-assets.com/118114114/thumbnails/1.jpg)
](Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry, 2004
Schiff base type mononuclear complexes of hexaaza[17]paracyclophane [MLX 2 ] [M ¼ Co(II), Ni(II),... more Schiff base type mononuclear complexes of hexaaza[17]paracyclophane [MLX 2 ] [M ¼ Co(II), Ni(II), Cu(II), and Zn(II); X ¼ Cl or NO 3 ] have been synthesized by the template condensation reaction of terephthalaldehyde, diethylenetriamine, and formaldehyde in 1 : 1 : 2 : 1 molar ratio in methanol. The FT-IR, 1 H NMR, and 13 C NMR data indicate that not all of the nitrogen atoms of the macrocyclic ring are coordinated to the metal centre. The reflectance spectra of the solid complexes were recorded confirming the penta-coordinated geometry around the metal
Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry, 2004
The template condensation reaction of 2,6‐diacetylpyridine and 2,6‐diaminopyridine forms a novel ... more The template condensation reaction of 2,6‐diacetylpyridine and 2,6‐diaminopyridine forms a novel series of 20‐membered N8 macrocyclic complexes. The proposed stoichiometry and the nature of the macrocyclic complexes have been confirmed on the basis of elemental analyses and conductivity data, respectively. The bonding in these complexes has been envisaged from the findings of IR and H NMR spectral studies, while the
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2006
Schiff base tetraazamacrocyclic ligand, L (C 40 H 28 N 4) and its complexes of types, [MLX 2 ] an... more Schiff base tetraazamacrocyclic ligand, L (C 40 H 28 N 4) and its complexes of types, [MLX 2 ] and [CuL]X 2 (M = Co(II), Ni(II), Zn(II); X = Cl − , NO 3 −) were synthesized and characterized by elemental analyses, mass, 1 H NMR, IR, UV-vis, magnetic susceptibility and molar conductance data. An octahedral geometry has been proposed for all the complexes except the copper(II) complexes which have a square planar environment. The reducing power of the Co(II) and Cu(II) complexes have been checked and compared. The ligand (L) and its complexes have also been screened against different fungi and bacteria in vitro.
Current Topics in Chikungunya, 2016
Dengue and Chikungunya fever are the arboviral infections that are endemic in tropical and subtro... more Dengue and Chikungunya fever are the arboviral infections that are endemic in tropical and subtropical regions. These two viral infections share common clinical symptoms. These infections are transmitted by a common mosquito vector so these viruses co-circulate in many geographical regions. Various clinical investigations, particularly from India and African countries have documented the dual infection with these viruses. However, the true disease burden of Dengue and Chikungunya dual viral infections is still not known because most of these studies involved a smaller patient group. Therefore, in depth investigations involving larger patient groups are needed to examine the complete pathogenicity and severity of the dual viral infections. The timely diagnosis of the pathogens and correlation of disease severity with mono or dual infections is essential for effective patient management. In addition, the detailed molecular and cellular mechanism of co-infection should be investigated to describe a complete picture of the interaction of two viral pathogens in the host cell. Further comprehensive studies of dual infections from the endemic regions will determine the epidemiological and evolutionary pattern of these emerging viruses. This data will also assist in designing and implementation of effective control measures.
PLoS neglected tropical diseases, 2016
Dengue fever is the most important arboviral disease in the tropical and sub-tropical countries o... more Dengue fever is the most important arboviral disease in the tropical and sub-tropical countries of the world. Delhi, the metropolitan capital state of India, has reported many dengue outbreaks, with the last outbreak occurring in 2013. We have recently reported predominance of dengue virus serotype 2 during 2011-2014 in Delhi. In the present study, we report molecular characterization and evolutionary analysis of dengue serotype 2 viruses which were detected in 2011-2014 in Delhi. Envelope genes of 42 DENV-2 strains were sequenced in the study. All DENV-2 strains grouped within the Cosmopolitan genotype and further clustered into three lineages; Lineage I, II and III. Lineage III replaced lineage I during dengue fever outbreak of 2013. Further, a novel mutation Thr404Ile was detected in the stem region of the envelope protein of a single DENV-2 strain in 2014. Nucleotide substitution rate and time to the most recent common ancestor were determined by molecular clock analysis using B...
Pathogens and disease, Jan 10, 2015
The Chikungunya virus is a re-emerging alphavirus that belongs to family Togaviridae. The symptom... more The Chikungunya virus is a re-emerging alphavirus that belongs to family Togaviridae. The symptoms include fever, rashes, nausea and joint pain that may last for months. The laboratory diagnosis of the infection is based on the serologic assays, virus isolation and molecular methods. The pathogenesis of the Chikungunya viral infection is not completely understood. Some of the recent investigations have provided information on replication of the virus in various cells and organs. In addition, some recent reports have indicated that the severity of disease is correlated with the viral load and cytokines.The Chikungunya virus infection re-emerged as an explosive epidemic during 2004-09 affecting millions of people in the Indian Ocean. Subsequent global attention was given to research on this viral pathogen due to its broad area of geographical distribution during this epidemic. Chikungunya viral infection has become a challenge for the public health system because of absence of a vacci...
PLOS ONE, 2015
Dengue fever is the most prevalent arboviral disease in the tropical and subtropical regions of t... more Dengue fever is the most prevalent arboviral disease in the tropical and subtropical regions of the world. The present report describes molecular detection and serotyping of dengue viruses in acute phase blood samples collected from New Delhi, India. Phylogenetic and molecular clock analysis of dengue virus serotype 1 and 3 strains were also investigated. Dengue virus infection was detected in 68.87% out of 604 samples tested by RT-PCR between 2011 & 2014. Dengue serotype 1 was detected in 25.48% samples, dengue serotype 2 in 79.56% samples and dengue serotype 3 in 11.29% samples. Dengue serotype 4 was not detected. Co-infection by more than one dengue serotype was detected in 18.26% samples. Envelope gene of 29 DENV-1 and 14 DENV-3 strains were sequenced in the study. All the DENV-1 strains grouped with the American African genotype. All DENV-3 strains were found to belong to Genotype III. Nucleotide substitution rates of dengue 1 and 3 viruses were determined in the study. Time to the most recent common ancestor (TMRCA) of dengue 1 viruses was determined to be 132 years. TMRCA of DENV-3 viruses was estimated to be 149 years. Bayesian skyline plots were constructed for Indian DENV-1 and 3 strains which showed a decrease in population size since 2005 in case of DENV-1 strains while no change was observed in recent years in case of DENV-3 strains. The study also revealed a change in the dominating serotype in Delhi, India in recent years. The study will be helpful in formulating control strategies for the outbreaks. In addition, it will also assist in tracking the movement and evolution of this emerging virus.
VirusDisease, 2015
Human respiratory syncytial virus (hRSV) is the most common viral pathogen of acute lower respira... more Human respiratory syncytial virus (hRSV) is the most common viral pathogen of acute lower respiratory tract infection in infants and young children. The G protein of hRSV is the trans-membrane glycoprotein that is involved in the attachment of virion with the host cell. The nasopharyngeal aspirates were subjected to RT-PCR for the second hypervariable region of the G protein gene in the present investigation. Sequencing and phylogenetic analysis revealed that all the study strains clustered within the BA genotype. The study sequences further clustered in BA-9, BA-7, BA-10 and BA-12 subgroups within the BA genotype. The G proteins of the study sequences were predicted to encode 312 and 319 amino acids. Three different N-linked glycosylation sites were observed in the deduced 93-100 amino acid region. There were 40-43 serine and threonine residues that are the potential O-linked glycosylation sites. The non-synonymous/synonymous (dN/dS) ratio was less than one indicating negative selection pressure for amino acid change in the analyzed region of the G protein. The present investigation provides information on circulating strains of BA genotype from New Delhi, India. Further elaborate investigations of the BA viruses from different regions of the world will establish the basis of the rapid global spread and evolutionary pattern of this expanding genotype. Keywords BA genotype Á G protein gene Á Human respiratory syncytial virus Á Phylogenetic analysis VLN Raghuram S and Wajihul Hasan Khan have contributed equally to this work.
Preparative biochemistry & biotechnology, Jan 7, 2015
Human respiratory syncytial virus (hRSV) is an important pathogen of acute respiratory tract infe... more Human respiratory syncytial virus (hRSV) is an important pathogen of acute respiratory tract infection. The human respiratory syncytial virus (hRSV) expresses major surface transmembrane glycoproteins, F and G. The G protein of hRSV is a neutralizing antigen and is thus a vaccine candidate. The G protein of hRSV consists of three functional domains, namely N-terminal cytoplasmic region, attachment region and ectodomain region. In the present study, ectodomain G protein, G(▵TM) was cloned and expressed in prokaryotic system. The codon optimized ectodomain G protein gene of BA genotype of group B hRSV strain was amplified from synthetic gene. The amplified fragment was cloned into pGEMT-easy vector and subcloned into pET-28a vector. The protein was expressed in BL21-AI cells. The G(▵TM) was purified with Ni-NTA column. The purified protein was used for biophysical characterization, including circular dichroism, as well as thermal and chemical denaturation. The molar absorption co-effi...
In the present work, braided composite rods (BCRs) have been developed through braiding of polypr... more In the present work, braided composite rods (BCRs) have been developed through braiding of polypropylene (PP) fibres around an axially oriented core, made of a mixture of PP and sisal fibres and subsequent consolidation of the produced structures under heat and pressure. Tensile properties of these BCRs were characterized. The effect of alkali treatment of sisal fibres on their surface morphology as well as mechanical properties of sisal fibres and produced BCRs was thoroughly investigated. It was observed that the tensile properties of developed BCRs improved strongly with the increase in sisal fibre vol.% and moreover, the alkali treatment improved the tensile properties of sisal fibre and their interfacial interactions with PP matrix, leading to enhanced tensile behaviour of BCRs.
Carbon nanotubes (CNTs) are finding widespread applications in various fields including catalyst ... more Carbon nanotubes (CNTs) are finding widespread applications in various fields including catalyst supports, optical devices, quantum computers, and biomedical field due to their unique electronic, thermal, optical, and mechanical properties [1, 2]. Most of these applications require stable suspensions of high concentration of CNTs. The non-covalent functionalization technique of producing CNT suspensions is better in the sense that it does not alter the inherent electrical, optical or mechanical properties of CNT. In this route, CNTs are commonly dispersed using various surfactants, such as etyltrimethylammonium bromide, Triton X-100, sodium dodecylbenzene sulfonate (SDBS), Pluronic F127, etc. [3], with the help of ultrasonication process, which breaks down or de-bundles the CNT aggregates. The treatment time or energy of the ultrasonication process has strong influence on CNT dispersion and within limits, longer is the treatment time (and higher is the ultrasonication energy), better is the CNT dispersion. However, a longer ultrasonication treatment or higher ultrasonication energy may also reduce the aspect ratio and lead to CNT damage. From this point of view, a short and mild dispersion process is always favourable. On the other hand, among the various surfactants, currently Pluronics are finding a special attention due to its biocompatibility and lower toxicity as compared to other surfactants [4]. However, only limited number of research studies has been carried out till date on the aqueous dispersion of CNT using Pluronic, especially at high concentrations.
ISRN Nanomaterials, 2012
We observe hysteresis in J-E plot during field emission measurement of CNTs grown by LPCVD techni... more We observe hysteresis in J-E plot during field emission measurement of CNTs grown by LPCVD technique. CNTs are synthesized on Fe-coated Si substrate at 650°C. SEM and Raman study confirm that CNTs are successfully grown on Si substrate by LPCVD technique. In this study, we find that ramp-down curve has higher value of current density than ramp-up curve which indicates that CNTs show positive hysteresis. Our results show that a high current density at low turn-on voltage is obtained in ramp-down step of J-E plot which may be since not all CNTs contribute in ramp-up step process. But in ramp-down step all CNTs contribute as field emitters due to high electric field treatment. We also performed stability analysis of CNTs with current at constant applied voltage for 5 hrs and find that the sample shows long-term stability due to increase in emitting site density since a large number of CNTs participate in field emission.
Environmental Science and Engineering, 2013
In this work, ultra long vertically aligned single wall carbon nanotubes are synthesised by Plasm... more In this work, ultra long vertically aligned single wall carbon nanotubes are synthesised by Plasma enhanced chemical vapour deposition (PECVD) technique at 600 °C temperature. The presence of built-in electric field in a plasma sheath aligns the growing CNTs along the field lines. Also, PECVD method favours low temperature synthesis of VA-SWCNTs. SEM and Raman are used to characterized as grown sample. Enhanced Field emission properties of as-grown VA-SWCNTs are also studied.
Journal of Nanomaterials, 2013
Excellent mechanical, thermal, and electrical properties of carbon nanotubes (CNTs) and nanofiber... more Excellent mechanical, thermal, and electrical properties of carbon nanotubes (CNTs) and nanofibers (CNFs) have motivated the development of advanced nanocomposites with outstanding and multifunctional properties. After achieving a considerable success in utilizing these unique materials in various polymeric matrices, recently tremendous interest is also being noticed on developing CNT and CNF reinforced cement-based composites. However, the problems related to nanomaterial dispersion also exist in case of cementitious composites, impairing successful transfer of nanomaterials' properties into the composites. Performance of cementitious composites also depends on their microstructure which is again strongly influenced by the presence of nanomaterials. In this context, the present paper reports a critical review of recent literature on the various strategies for dispersing CNTs and CNFs within cementitious matrices and the microstructure and mechanical properties of resulting nano...
Textile Science and Clothing Technology, 2014
This chapter discusses the present scenario and market trend of some important natural plant fibe... more This chapter discusses the present scenario and market trend of some important natural plant fibers such as cotton, flax, jute, and hemp. Production, processing, and applications of these fibers are discussed. The factors influencing the sustainability of these natural plant fibers are presented and various lifecycle assessment studies performed on these fibers to evaluate their environmental impacts and sustainability are discussed.
Textile Science and Clothing Technology, 2014
ABSTRACT This chapter discusses the present scenario and market trend of regenerated cellulosic f... more ABSTRACT This chapter discusses the present scenario and market trend of regenerated cellulosic fibers, and the properties of principal fibers existing in the market as well as some new fibers recently developed and yet to be explored. Production technologies of these fibers are discussed and their potential applications are presented. Various sustainability issues related to the production of regenerated cellulosic fibers are dealt within this chapter. The last section discusses the results of research studies conducted to assess the environmental impacts and sustainability aspects of regenerated cellulose fibers.
Transition Metal Chemistry, 2006
... Mohammad Shakir*, Shakira Khatoon, Shama Parveen and Yasser Azim Division of Inorganic Chemis... more ... Mohammad Shakir*, Shakira Khatoon, Shama Parveen and Yasser Azim Division of Inorganic Chemistry, Department of Chemistry, Aligarh Muslim University, Aligarh 202002 ... of the metal free ligand, L confirms the proposed formula by showing a peak at m/z 773 corresponding ...
Transition Metal Chemistry, 2004
Complexes of the type [M(tren)(abpt)](NO 3) 2 (H 2 O) n (1-6) [M ¼ Mn II , Fe II , Co II , Cu II ... more Complexes of the type [M(tren)(abpt)](NO 3) 2 (H 2 O) n (1-6) [M ¼ Mn II , Fe II , Co II , Cu II , Zn II (n ¼ 2), Ni II (n ¼ 2.25), tren ¼ tris(2-aminoethyl)amine, and abpt ¼ 4-amino-3,5-bis(pyridin-2yl)-1,2,4 triazole] have been prepared. The bonding mode and overall geometry of the complexes have been deduced by elemental analyses, molar conductance values, spectral studies (obtained from FT-IR), 1 H-n.m.r., electronic spectral analyses and magnetic susceptibility measurements. A detailed molecular structure of complex (4) has been determined by single X-ray crystallography.
Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry, 2004
Schiff base type mononuclear complexes of hexaaza[17]paracyclophane [MLX 2 ] [M ¼ Co(II), Ni(II),... more Schiff base type mononuclear complexes of hexaaza[17]paracyclophane [MLX 2 ] [M ¼ Co(II), Ni(II), Cu(II), and Zn(II); X ¼ Cl or NO 3 ] have been synthesized by the template condensation reaction of terephthalaldehyde, diethylenetriamine, and formaldehyde in 1 : 1 : 2 : 1 molar ratio in methanol. The FT-IR, 1 H NMR, and 13 C NMR data indicate that not all of the nitrogen atoms of the macrocyclic ring are coordinated to the metal centre. The reflectance spectra of the solid complexes were recorded confirming the penta-coordinated geometry around the metal
Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry, 2004
The template condensation reaction of 2,6‐diacetylpyridine and 2,6‐diaminopyridine forms a novel ... more The template condensation reaction of 2,6‐diacetylpyridine and 2,6‐diaminopyridine forms a novel series of 20‐membered N8 macrocyclic complexes. The proposed stoichiometry and the nature of the macrocyclic complexes have been confirmed on the basis of elemental analyses and conductivity data, respectively. The bonding in these complexes has been envisaged from the findings of IR and H NMR spectral studies, while the
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2006
Schiff base tetraazamacrocyclic ligand, L (C 40 H 28 N 4) and its complexes of types, [MLX 2 ] an... more Schiff base tetraazamacrocyclic ligand, L (C 40 H 28 N 4) and its complexes of types, [MLX 2 ] and [CuL]X 2 (M = Co(II), Ni(II), Zn(II); X = Cl − , NO 3 −) were synthesized and characterized by elemental analyses, mass, 1 H NMR, IR, UV-vis, magnetic susceptibility and molar conductance data. An octahedral geometry has been proposed for all the complexes except the copper(II) complexes which have a square planar environment. The reducing power of the Co(II) and Cu(II) complexes have been checked and compared. The ligand (L) and its complexes have also been screened against different fungi and bacteria in vitro.