Butea monosperma bark extract mediated green synthesis of silver nanoparticles: Characterization and biomedical applications

AbstractThe work deals with an environmentally benign process for the synthesis of silver nanoparticle using Butea monosperma bark extract which is used both as a reducing as well as capping agent at room temperature. The reaction mixture turned brownish yellow after about 24h and an intense surface plasmon resonance (SPR) band at around 424nm clearly indicates the formation of silver nanoparticles. Fourier transform-Infrared (FT-IR) spectroscopy showed that the nanoparticles were capped with compounds present in the plant extract. Formation of crystalline fcc silver nanoparticles is analysed by XRD data and the SAED pattern obtained also confirms the crystalline behaviour of the Ag nanoparticles. The size and morphology of these nanoparticles were studied using High Resolution Transmission Electron Microscopy (HRTEM) which showed that the nanoparticles had an average dimension of ∼35nm. A larger DLS data of ∼98nm shows the presence of the stabilizer on the nanoparticles surface. The bio-synthesized silver nanoparticles revealed potent antibacterial activity against human bacteria of both Gram types. In addition these biologically synthesized nanoparticles also proved to exhibit excellent cytotoxic effect on human myeloid leukemia cell line, KG-1A with IC50 value of 11.47μg/mL

Salesperson reaction to management lead generation programs: The paradox investigated

Spiralling sales costs have caused researchers to explore several determinants of sales performance in order to make salespeople more productive. One avenue for raising productivity that is being pursued by companies is management lead generation programs. Management-generated leads are product- and service-related inquiries directed to the organization by potential customers as a result of exposure to different marketing communications aimed at them by the company, e.g., trade shows, advertisements in print media/public broadcast, telemarketing, direct mail, sales seminars, and product demonstrations. Lead generation programs are undertaken by organizations to help salespeople target better prospects, and consequently generate more sales with less effort, increase productivity, and yield more time to contact new prospects. Hence, it is expected that salespeople will greet leads with great enthusiasm. However, many companies are surprised to find their salespeople not following up on the generated leads. The above paradox, whereby salespeople treat leads with apathy despite postulated salesperson benefits of lead pursuit, is a major managerial dilemma, which has short term implications in terms of enormous wastage of management resources, and serious long term implications resulting from prospect dissatisfaction when salespeople fail to contact them. This demonstrates a need to study the management-lead follow-up phenomenon to get insights into the causes of the resistance of many salespeople to lead follow-up. This requires an understanding of what determines management-lead follow-up and whether salespeople actually gain from lead follow-up. This dissertation examines the paradox (zealous management, apathetic salespeople) by conducting a cross-industry field study to understand which salespeople are more likely to respond favorably to management leads, what are the critical influences on lead follow-up, and what is the impact of lead pursuit on salesperson performance. Data collected from a variety of firms and analyzed using Tobit, indicate that contrary to the traditional beliefs of management and trade press, salespeople predominantly act logically in their lead follow-up behavior. Further, investigation of the relationship between management-lead pursuit and salesperson performance, using OLS, shows positive relationship with a salesperson\u27s prospect conversion rate and new business performance

Degradation of Methyl Parathion, a common pesticide and fluorescence quenching of Rhodamine B, a carcinogen using β-d glucan stabilized gold nanoparticles

Natural carbohydrate polymer β-d-glucan extracted from Tricholoma crassum (Berk.) Sacc. predominantly linked by β-glycosidic bonds have been used to synthesize gold nanoparticles (Au NPs). As glucan is water soluble, the Au NPs are prepared in water medium, a green solvent. The morphology and characterization of the synthesized Au NPs have been confirmed by various techniques, like TEM, EDX, XRD, UV–Vis and FT-IR spectroscopic studies. The obtained Au NPs exhibits chemosensing property against Methyl Parathion, a group of highly toxic organophosphorous pesticide, extensively used as an agricultural chemical. Degradation of parathion using Au NPs lead to water-soluble products thereby reducing the toxicity of Methyl Parathion by disrupting the thiophosphate-ester linkage. The synthesized Au NPs also act as a good fluorescence quencher of Rhodamine B, a common fluorophore and carcinogenic compound, obeying Stern-Volmer equations. The β-d-glucan capped Au NPs are safe having possible medicinal usage. Keywords: β-d-Glucan, Gold nanoparticles, Green synthesis, Methyl Parathion, Fluorescence quenche

An efficient protocol for <i style="">in vitro</i> regeneration of <i>Podophyllum hexandrum</i>, a critically endangered medicinal plant

217-220Rhizome explants were used to develop a protocol for in vitro plantlet regeneration of Podophyllum hexandrum, a critically endangered medicinal plant, through direct organogenesis. Highest rate of multiple shoot formation was noted in MS medium supplemented with 11.42 μM IAA within three months. A synergistic effect of 2.68 μM NAA and 11.1 μM BAP was second best. The ½ MS liquid medium with 100 μM IBA was most suitable for rooting of shoots. Leaf explants resulted in callus formation only. Leaf regenerated calli showed the presence of podophyllotoxin in HPLC analysis

Agrobacterium-mediated genetic transformation of mint with E. coli glutathione synthetase gene

Morphologically identical transgenic mint (Mentha arvensis L.) with bacterial glutathione synthetase gene has been developed. Transformed plants were obtained by co-cultivation of leaf disks with Agrobacterium tumefaciens strain LBA 4404 harbouring a binary vector pCAMBIA-CpGS that carried E. coli glutathione synthetase (GS), b-glucuronidase as reporter gene and nptII as selective marker gene for kanamycin resistance. Using a constitutive double CaMV 35S promoter and an rbcS transit peptide, we successfully addressed CpGS to the chloroplasts through pJIT 117 vector. Preculture and the presence of AS in the co-cultivation medium played a significant role in enhancing transformation frequency. The highest transformation frequency was achieved with MS selection medium supplemented with 25% coconut water, 1.12 mg l-1 BAP, 0.2 mg l-1 NAA, 50 mg l-1 kanamycin and 125 mg l-1 cefotaxime. Robust rooting of regenerated shoots was obtained in half-strength liquid MS medium containing 0.2 mg l-1 NAA and 50 mg l-1 kanamycin. The presence and expression of transgenes in transgenics (T0) was evidenced by GUS histoenzymatic assay, PCR and RT-PCR analysis of nptII and the gene of interest, i.e., GS of putative transgenic leaves. Chromosomal integration of GS gene was confirmed by Southern blot analysis. Transgenic plants were successfully acclimatized in the greenhouse. An overall transformation frequency of 15% was achieved in approximately 3 months of time period. These results are discussed in relation to heavy metal trafficking pathways in higher plants and to the interest of using plastid expression of PCS for biotechnological applications

Novel hexagonal polytypes of silver: growth, characterization and first-principles calculations

We report a study of the relative effects of dimensional and kinetic constraints on the stabilization of metastable, polytypic forms of metallic silver. We show that the hexagonal 4H polytype (hitherto observed only in size-constrained systems) can be produced in the form of bulk thin films by suitably slowing down the growth kinetics. Further, using extremely slow growth conditions, we have been successful in depositing a novel, two-dimensional, metastable polytype (2H) of silver, which is highly reactive (easily oxidized) and has a density 23% lower than normal silver. First-principles calculations based on density functional theory confirm that the 4H structure is relatively stable. However, local stability analysis via a determination of the phonon dispersion of the 2H structure reveals that it is only marginally stable with an energy surface that is rather flat or weakly varying with respect to many of the modes. This makes a large contribution to the configurational entropy and is probably the reason for the metastability of the observed 2H polytype with an unusually large lattice constant along the c-direction

Synthesis, crystal structure, antimicrobial screening and density functional theory calculation of Nickel (II), Cobalt (II) and Zinc (II) mononuclear Schiff base complexes

[eng] Nickel(II), cobalt(II) and zinc(II) mononuclear Schiff base complexes of general formula [MIIL(H2O)3] 2H2O (where M = Ni, Co and Zn) have been synthesized using a new Schiff base ligand (LH2 = 2-((Pyridin-2- yl)methyleneamino)benzene-1,4-dioic acid). All the complexes and the ligand have been characterized by various physical measurements such as elemental analyses, FT-IR and UV-Vis spectroscopic techniques. The crystal structure analyses of the complexes revealed that extensive supramolecular interactions such as hydrogen bond and p-p stacking results 3D array of packing. The hydrogen bonding interaction distances are very similar in all complexes and are around 2.0 Å and for the p-p interactions the values are close to 3.8 Å. The interaction energies are comparable for Ni and Co complexes and is somewhat stronger for Zn complex. The strength of the aforementioned interactions have been evaluated by means of DFT calculations. For in vitro antimicrobial activity study, the complexes were screened against some bacteria and fungi. This study shows that the zone of inhibition against growth of microorganisms is much larger for Zn complex due to strong binding energy. The Hirshfeld surfaces of Ni, Co and Zn complexes were also analyzed to clarify the nature of the intermolecular interactions. Thermogravimetric analyses were performed to investigate the thermal stability of the complexes