oalib

OALib Journal期刊

ISSN: 2333-9721

费用：99美元

投稿

时间不限

( 2673 )

( 2672 )

( 2454 )

( 2208 )

自定义范围…

匹配条件： “Oswald N. Nfor” ，找到相关结果约234320条。
列表显示的所有文章，均可免费获取
第1页/共234320条
每页显示 条
Nickel (II) and Iron (II) Complexes with Azole Derivatives: Synthesis, Crystal Structures and Antifungal Activities
Emmanuel N. Nfor,Peter F. Asobo,Justin Nenwa,Oswald N. Nfor,Julius N. Njapba,Romanus N. Njong,Offiong E. Offiong
International Journal of Inorganic Chemistry , 2013, DOI: 10.1155/2013/987574
Abstract: Two new complexes of nickel (II) with 4-amino-3, 5-bis(pyridyl)-1, 2, 4-triazole (abpt) and iron (II) with 2-(3-phenyl-1H-pyrazole-5-yl) pyridine (phpzpy) have been synthesized and characterized by elemental analysis and IR spectroscopy. The crystal structures of the complexes have been determined by single crystal X-ray diffraction techniques. In the nickel and iron complexes, the ligands are coordinated through nitrogen atoms in bidentate manner. The ligands and their respective complexes have been tested for their antifungal activity against Aspergillus niger, Aspergillus flavus, and Candida albicans. From the study, the complexes showed enhanced activities against the tested organisms compared to the ligands. 1. Introduction Aromatic nitrogen heterocycles represent an important class of compounds which can act as ligands towards metal ions [1]. Azoles belong to this class and are five-membered heterocyclic ligands containing two or more heteroatoms, one of which must be nitrogen. These compounds have been paid considerable attention due to their wide applicability in medicine [2–4]. Pyrazole and triazole derivatives are subject of many research studies due to their widespread potential biological activities such as antitumour [5, 6], anti-inflammatory [7], antipyretic [8], antivirial [9], antimicrobial [10, 11], anticonvulsant [12], antihistaminic [13], antidepressant [14, 15], insecticides, and fungicides. In coordination chemistry pyrazole-and triazole-derived ligands exhibit various coordination modes and have received considerable attention for the synthesis of transition metal complexes with various nuclearities [16]. Herein we report on the synthesis, structural determination, and antifungal activities of Ni(II) and Fe(II) complexes of abpt and phpzpy, respectively. The crystal structures of the complexes are described and compared with those of closely related structures. 2. Experimental 2.1. Materials and Physical Measurements Elemental analysis for carbon, hydrogen, and nitrogen was performed on a Thermo Flash EA-1112 Series CHNS-O Elemental Analyzer. The IR spectra were obtained from KBr pellets in the range 4000–400？cm？1 using a Perkin-Elmer Spectrum 100？FT-IR spectrometer. 2.2. Single Crystal X-Ray Diffraction Analysis and Structure Determination Suitable-single crystals of 1 and 2 were selected and mounted in air onto a loop. The data collection for 1 and 2 was carried out with a Bruker DUO APEX II CCD diffractometer at 173 ？K using an Oxford cryostream 700. Data reduction and cell refinement were performed using SAINT-Plus, [17–21] and
Antimicrobial Resistance Profile of Bacteria Isolated from Boreholes and Hand Dug Wells Water in Ngaoundere Municipality of Adamawa Region in Cameroon  [PDF]
Bernard Viban Tangwa, Horline Keubou, Emmanuel N. Nfor, Albert Ngakou
Advances in Microbiology (AiM) , 2019, DOI: 10.4236/aim.2019.97039
Abstract: Uncontrolled uses of antibiotics have led to rapid evolution of antibiotic-resistance bacteria and antibiotic resistance gene transfer, especially in a pool of aquatic system where resistance, intermediate and susceptible bacteria to some antibiotics strive together. Consequently, there is a transfer of resistance genes. In this study, bacteria of the Enterobacteriaceae family and some gram positive bacteria isolated from some boreholes and hand dug wells water of public use were tested on 19 antibiotics of different classes. This was achieved through a disk diffusion technique to determine the antimicrobial resistance profile of the said bacteria, microbial resistance index of the drugs used (and their ability to produce Beta-lactamase). These isolates were shown to demonstrate a very high resistance to the drugs used in the area. The resistance was highest in Escherichia coli 1 (73.68%) and lowest in Streptococcus pneumoniae (47.82%). These isolates also indicated very high levels of multi-drug resistance. The minimum resistance index was 0.47, indicating that bacteria isolates were of fecal origin. It is evident from the present study that multiple antibiotic-resistant bacteria can thrive in water as an environmental reservoir, and can therefore provide a route to multidrug-resistant pathogens to enter human and animal population.
Corrosion Inhibitory Studies of Novel Schiff Bases Derived from Hydralazine Hydrochloride on Mild Steel in Acidic Media  [PDF]
Romanus N. Njong, Bridget N. Ndosiri, Emmanuel N. Nfor, Offiong E. Offiong
Open Journal of Physical Chemistry (OJPC) , 2018, DOI: 10.4236/ojpc.2018.81002
Abstract: The inhibition performance of 1-hydralazinophthalazine (HPZ) (1), and synthesized1-(2-[(5-methylfuran-2-yl)methylene)] hydrazono) phthalazine (MFHPZ) (2), 1-(phthalazin-1(2H)-one) [(pyridin-2-yl) ethylidene] hydrazone (ACPHPZ) (3) and (2-acetylthiophene hydrazono) phthalazine (ACTHPZ) (4) has been investigated for mild steel in 1 M HCl. Compound 4 shows maximum inhibition efficiency of 93% at 5.0 × 10-3 M concentration. The evaluation of thermodynamics and activation parameters indicated spontaneous adsorption of the inhibitor molecules which takes place through chemisorption. The adsorption of 3 and 2 follows Langmuir adsorption isotherm and Temkin adsorption isotherm for 4 and 1. The inhibitor efficiency was of the order 4 > 3 > 1
Synthesis, Molecular Structure and Anti-Onchocercal Studies of 1-(Phthalazin-1(2H)-one)[(Pyridin-2-yl)ethylidene]hydrazone  [PDF]
Joseph N. Yong, Felicite Majoumo-Mbe, Moses Samje, Emmanuel N. Nfor
International Journal of Organic Chemistry (IJOC) , 2016, DOI: 10.4236/ijoc.2016.61008
Abstract: The novel ligand, 1-(phthalazin-1(2H)-one)[(pyridin-2-yl)ethylidene]hydrazone,(APN), derived from the antihypertensive drug, hydralazine hydrochloride, was synthesized and characterized by spectroscopic methods (IR, 1H NMR). The X-ray crystallographic data indicates that APN has an exocyclic C=N bond on the hydralazine moiety. APN revealed significant anti-onchocercal activity with IC50 values of 0.3125 μg/mL on microfilaria and 10 μg/mL on adult worms compared to the standard drug, ivermectin.
Synthesis, Molecular Structure and Antibacterial Activity of Benzylmethyl-4-Methyl-3-Thiosemicarbazone  [PDF]
James A. Mbah, Godfred A. Ayimele, Elvis N. Eyonganyoh, Emmanuel N. Nfor
International Journal of Organic Chemistry (IJOC) , 2017, DOI: 10.4236/ijoc.2017.72007
Abstract: A novel Schiff base, benzylmethyl-4-methyl-3-thiosemicarbazone (BMM) de-rived from benzylmethylketone and 4-methylthiosemicarbazide was synthe-sized and characterized by elemental analysis, spectroscopic methods (IR, 1H NMR, 13C NMR) and physical means. The single crystal structure analysis of the Schiff base reveals that it crystallizes in a monoclinic system in the P21/c space group. BMM revealed moderate antibacterial activity on three bacterial strains with diameter zone of inhibition of 16 mm (E. coli), 14 mm (K. pneumonia) and 13 mm (S. epider-midis) compared with the standard drug, ciprofloxacin.
Ni(II) N-(2-Pyridylmethyl)-L-Alanine) Complex: Structural Diversity and Photoluminiscent Studies  [PDF]
Bridget N. Ndosiri, Emmanuel N. Nfor, Jér？me Marrot, Aminou Mohamadou, Justin Nenwa
Crystal Structure Theory and Applications (CSTA) , 2020, DOI: 10.4236/csta.2020.94006
Abstract: A novel chiral Nickel (II) complex of N-(2-pyridylmethyl)-L-alanine (Hpyala) 1 has been prepared and structurally characterized by elemental analysis, FT-IR, UV-visible, TGA and single crystal X-ray diffraction techniques. Complex 1 crystallizes in an orthorhombic P212121 space group. The nickel (II) centre in the complex adopts a distorted octahedral geometry. This compound has been seen to exhibit structural diversity resulting from the number of lattice water molecules. The photoluminescent properties of this compound which have also been investigated, indicates the potential application in luminescence.
Synthesis, Spectroscopic, Molecular Modeling and Anti-Fungal Studies of Some Divalent Metal Complexes of 4-Hydroxyacetophenone Isonicotinoyl Hydrazone  [PDF]
Gwendoline M. Toh-Boyo, Romanus N. Njong, Estella M. Babette, Emmanuel N. Nfor
Open Journal of Inorganic Chemistry (OJIC) , 2021, DOI: 10.4236/ojic.2021.113007
Abstract: A novel ligand N-4-hydroxyacetophenone isonicotinoyl hydrazone and its manganese(II) and nickel(II) metal complexes have been synthesized. The synthesized Schiff base and its metal complexes have been characterized by physical state determination, melting point and solubility measurements in different solvents, infrared, proton nuclear magnetic resonance, mass spectrometric and powder X-ray spectroscopic techniques. The thermal properties of the prepared compounds were obtained from TG/DTG measurements. On the basis of the analytical techniques, the ligand was found to be bidentate in nature coordinating to the metal ions through the azomethine nitrogen and carbonyl oxygen atoms leading to distorted octahedral geometries of the metal complexes which were modeled using MM2 force field. The ligand and its metal(II) complexes were evaluated for antifungal activity against Aspergillus fumigatus, Aspergillus niger, Candida albicans and Rhizopus stolonifera. The antifungal evaluation results revealed an enhanced activity upon coordination of the ligand with the metal(II) ions. The activity of the metal complex to the tested fungal strains was in the order Ni(II) > Mn(II).
Synthesis and Crystal Structure of the First Example of a Tris-Chelated Co(II) Complex Based on Oxamide Dioxime Ligand  [PDF]
Gouet Bebga, Emmanuel N. Nfor, Yves A. Mbiangué, Patrick L. Djonwouo, Justin Nenwa
Crystal Structure Theory and Applications (CSTA) , 2015, DOI: 10.4236/csta.2015.42002
Abstract: A new cobalt(II) complex, [Co(H2 oxado)3 ]C2 O4 H2 oxado·2H2 O (H2 oxado = oxamide dioxime), has been synthesized in aqueous solution and characterized by elemental analysis and single crystal X-ray structure determination. The complex crystallizes in the triclinic space group P-1, with the parameters a = 9.46(4), b = 11.84(5), c = 12. 81(5)？Å, α = 104.94(6), β = 99.29(5), γ = 106.73(5), V = 1284(9) Å3, Z = 2. The central cobalt(II) cation is pseudo-octahedrally coordinated by six imino N atoms of the neutral oxamide dioxime ligand. In the solid state, each of the following bricks, namely the cationic complexes, the oxalate dianions as well as the oxamide dioxime crystallization molecules, pile up parallel to the a axis. The bulk structure is consolidated by an extended three-dimensional network of hydrogen bridgings—that link the ionic partners, oxamide dioxime and water molecules to one another—and by coulombic interactions.
Higher Order Periodic Base Pairs Opening in a Finite Stacking Enthalpy DNA Model  [PDF]
Nkeh Oma Nfor
Journal of Modern Physics (JMP) , 2021, DOI: 10.4236/jmp.2021.1213107
Abstract: The dynamics of periodic base pairs opening in a finite stacking enthalpy DNA is investigated in this work. This is achieved by using the Joyeux-Buyukdagli DNA model, in which the polynomial approximations of the stacking interaction and Morse potential are expanded up to the fifth order nonlinear terms by using the Taylor series expansion technique. By incorporating the continuum limit approximation and the extended multiple scale asymptotic methods, higher order nonlinear Schrödinger amplitude equations are derived. In the limit of cubic nonlinearity, the periodic base pair configurations clearly depict the open state; with linear stability analysis exposing other periodic background modes that are vital in the DNA transcription, replication, and transmission of genetic codes. The higher order modes generally display a more robust and structurally stable wave profile, which epitomizes the base pair dynamics of the DNA molecule observed from experimental investigations. Prolonged time evolution of base pairs stretching greatly modifies the higher order modes of the DNA molecule, strongly suggesting that such modes may induce abnormalities like gene mutation which is responsible for numerous diseases.
The Impact of Aerobic Exercise and Badminton on HDL Cholesterol Levels in Adult Taiwanese
Disline Manli Tantoh,Kuan-Jung Lee,Ming-Chih Chou,Oswald Ndi Nfor,Yasser Nassef,Yung-Po Liaw
- , 2019, DOI: 10.3390/nu11030515
Abstract: Elevated levels of high-density lipoprotein cholesterol (HDL-C) have been associated with a decreased risk of coronary heart disease (CHD). An active lifestyle is necessary in order to improve lipid HDL-C, including (but not limited to) physical exercise. Research on the association between badminton, an intermittent exercise, and HDL-C is limited. We investigated the impact of aerobic exercise and badminton on HDL-C levels in Taiwanese adults. The sociodemographic data of 7797 participants comprising 3559 men and 4238 women aged between 30 to 70 years were retrieved from the Taiwan Biobank. The participants were grouped into three exercise categories—no exercise, aerobic exercise, and badminton exercise. The HDL-C levels were compared using an analysis of variance (ANOVA). The multivariate linear regression models were used to determine the associations between HDL and exercise. Comparing the other two groups to the no-exercise group, the individuals who were engaged in aerobic and badminton exercise were significantly associated with a higher HDL-C (β =1.3154; p <0.0001 and β = 6.5954; p = 0.0027, respectively). Aerobic exercise and badminton were also associated with higher HDL-C levels among carriers of the lipoprotein lipase (LPL) rs328 genotypes. Aerobic exercise and regular badminton were associated with higher levels of HDL-C, with the badminton group being more significant
第1页/共234320条
每页显示 条


Home
Copyright © 2008-2020 Open Access Library. All rights reserved.