The Interaction of Hypertension for Vertigo in Audiovestibular Medicine Clinic

Adaobi Elizabeth Osuji 대한평형의학회 2022 Research in Vestibular Science Vol.21 No.2

As the first audiovestibular medicine physician in the University of Port Harcourt Teaching Hospital, Nigeria, a keen observation revealed that a sizeable proportion of the adult patients presenting to our audiovestibular medicine clinic with vertigo are either known hypertensives, or hypertensives yet to have a formal diagnosis. This aroused an ardent curiosity to find the raison d’être, and to shed light on this pathological association between vertigo and hypertension. In line with this, it became imperative to highlight the dynamics of interaction, and pathophysio-logy behind the role of hypertension in vertigo.

Multivariate analysis of source and maturity biomarker indices of crude oils from SW Niger Delta

Leo C. Osuji,Nicolas C. Oforka,Mudiaga C. Onojake 한국지질과학협의회 2014 Geosciences Journal Vol.18 No.3

Saturated biomarker source and maturity parametersobtained from Gas chromatography-mass spectrometry wereanalyzed using multivariate statistical methods to maximize diagnosticinformation on the hopanes and sterane spectrum. This statisticalmethod provided the identification of structural relationships(similarities and differences) between various fingerprint descriptorsfor the crude oil samples. The results emphasized the separation ofthe oil samples in regards to their locations into two genetic families. This separation pattern is more evident when principal componentanalysis was applied to biomarker data compared with the standardbiomarker cross-plots. Such compositional differences are commonlyattributed to unique source rock paleodepositional environments. The plotted source and maturity diagnostic parameter in a dendrogramseparated the oils into two families both having terrestrialinput. The group that have higher terrestrial input contain moreoleananes, and have the highest Pr/Ph ratio. They are generated fromsource rocks with a high abundance of terrestrial organic matter. Thesecond groups of oils have mixes of terrestrial and marine organicmatter with lesser amount of oleananes.

A review of zinc oxide photoanode films for dye-sensitized solar cells based on zinc oxide nanostructures

Tyona, M.D.,Osuji, R.U.,Ezema, F.I. Techno-Press 2013 Advances in nano research Vol.1 No.1

Zinc oxide (ZnO) is a unique semiconductor material that exhibits numerous useful properties for dye-sensitized solar cells (DSSCs) and other applications. Various thin-film growth techniques have been used to produce nanowires, nanorods, nanotubes, nanotips, nanosheets, nanobelts and terapods of ZnO. These unique nanostructures unambiguously demonstrate that ZnO probably has the richest family of nanostructures among all materials, both in structures and in properties. The nanostructures could have novel applications in solar cells, optoelectronics, sensors, transducers and biomedical sciences. This article reviews the various nanostructures of ZnO grown by various techniques and their application in DSSCs. The application of ZnO nanowires, nanorods in DSSCs became outstanding, providing a direct pathway to the anode for photo-generated electrons thereby suppressing carrier recombination. This is a novel characteristic which increases the efficiency of ZnO based dye-sensitized solar cells.

Microbial Evaluation of Fodder Tree Leaves as Ruminant Feed

Odenyo, A.A.,Osuji, P.O.,Negassa, D. Asian Australasian Association of Animal Productio 1999 Animal Bioscience Vol.12 No.5

Fermentation of legume fodder tree leaves by rumen microorganisms was evaluated. The substrates were sun-dried, ground leaves. Gas and volatile fatty acid (VFAs) production were estimated. Using gas production as an index of fermentation at 12 h, the leaves tested ranked as follows; Chamaecytisus palmensis>Gliricidia sepium>Sebania sesban>Tephrosia bracteolate>Leucaena pallida>Vernonia amygdalina>Acacia sieberiana>Sesbania goetzei>Acacia angustissima. Using VFA production, the ranking was a follows; G. sepium>S. sesban>S. goetzei>L. pallida>C. palmensis/V. amygdalina>T. bracteolate> A. sieberiana>A. angustissima. Absolute gas or VFA production rates, were also used to rank the leaves. Extracts (70% acetone) of A. angustissima inhibited the growth of Ruminococcus albus 8, R. flavefaciens FD-1, Prevotella ruminicola D3ID and Streptococcus bovis JBI while the trowth of Selenomonas ruminantium D was depressed when 0.6 ml exracts were added. C. palmensis water extracts enhanced cellulose hydrolysis by R. flavefaciens FD-1. All extracts reduced celluloysis by R. albus 8. R. flavefaciens FD-1 hydrolyzed more (p<0.001) cellulose than R. albus 8.

Rheology of cellulose nanofibrils in the presence of surfactants

Quennouz, Nawal,Hashmi, Sara M.,Choi, Hong Sung,Kim, Jin Woong,Osuji, Chinedum O. Royal Society of Chemistry 2016 SOFT MATTER Vol.12 No.1

<P>Cellulose nanofibrils (CNFs) present unique opportunities for rheology modification in complex fluids. Here we systematically consider the effect of ionic and non-ionic surfactants on the rheology of dilute CNF suspensions. Neat suspensions are transparent yield-stress fluids which display strong shear thinning and power-law dependence of modulus on concentration, G' similar to c(2.1). Surfactant addition below a critical mass concentration cc produces an increase in the gel modulus with retention of optical clarity. Larger than critical concentrations induce significant fibril aggregation leading to the loss of suspension stability and optical clarity, and to aggregate sedimentation. The critical concentration was the lowest for a cationic surfactant (DTAB), c(c) approximate to 0.08%, while suspension stability was retained for non-ionic surfactants (Pluronic F68, TX100) at concentrations up to 8%. The anionic surfactant SDS led to a loss of stability at c(c) approximate to 1.6% whereas suspension stability was not compromised by anionic SLES up to 8%. Dynamic light scattering data are consistent with a scenario in which gel formation is driven by micelle-nanofibril bridging mediated by associative interactions of ethoxylated surfactant headgroups with the cellulose fibrils. This may explain the strong difference between the properties of SDS and SLES-modified suspensions. These results have implications for the use of CNFs as a rheology modifier in surfactant-containing systems.</P>

Continuous and patterned deposition of functional block copolymer thin films using electrospray

Hu, Hanqiong,Toth, Kristof,Kim, Myungwoong,Gopalan, Padma,Osuji, Chinedum O. Cambridge University Press (Materials Research Soc 2015 MRS Communications Vol.5 No.2

<▼1><B>Abstract</B><P/></▼1><▼2><P>We report the use of electrospray to continuously deposit thin films, including patterned films, of a block copolymer (BCP). High substrate temperatures led to vertically oriented cylindrical microdomains at the film surface independent of the solvent composition and deposition rates utilized. Conversely, low substrate temperatures resulted in morphologies that were more sensitive to these parameters, with poorly ordered films of globular structures observed at the lowest temperatures considered. The deposition pattern is defined by spatially varying the electric field at the substrate using an underlying charged grid. These results open up new possibilities for patterned deposition of BCP films with morphological control.</P></▼2>

Effect of Final Monomer Deposition Steps on Molecular Layer-by-Layer Polyamide Surface Properties

Tousley, Marissa E.,Shaffer, Devin L.,Lee, Jung-Hyun,Osuji, Chinedum O.,Elimelech, Menachem American Chemical Society 2016 Langmuir Vol.32 No.42

<P>A current challenge to desalination membrane technology is the inability to precisely control the properties of the polyamide selective layer due to the complexity of interfacial polymerization. In this study, we investigate the ability of molecular layer-by-layer (mLbL) assembly, an alternative polyamide fabrication technique, to create poly amide surfaces with tunable chemistry. We explore the influence of terminating monomer, monomer deposition time, monomer size, and the presence of underlying ionizable functional groups on mLbL-derived polyamide surface properties. AFM colloidal probe measurements, contact angle titration, QCM cesium adsorption experiments, and XPS data show that polyamide films terminated with m-phenylenediamine or trimesoyl chloride for 20-30 s are chemically similar. Increasing terminating monomer deposition time or using a smaller, more reactive monomer results in more distinct colloidal-probe adhesive interactions, contact angle titration curves, negative charge densities, and near surface atomic compositions. By optimizing the final monomer deposition steps, both amine rich and carboxyl-rich polyamide surfaces can be fabricated, which has implications for the application of mLbL assembly to membrane-based desalination.</P>

Smart Cellulose Nanofluids Produced by Tunable Hydrophobic Association of Polymer-Grafted Cellulose Nanocrystals

Lee, Yea Ram,Park, Daehwan,Choi, Sang Koo,Kim, Miju,Baek, Heung Soo,Nam, Jin,Chung, Chan Bok,Osuji, Chinedum O.,Kim, Jin Woong American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.36

<P>Cellulose fibrils, unique plant-derived semicrystalline nanomaterials with exceptional mechanical properties, have significant potential for rheology modification of complex fluids due to their ability to form a physically associated semiflexible fibrillary network. Here, we report new associative cellulose nanocrystals (ACNCs) with stress-responsive rheological behaviors in an aqueous solution. The surface-mediated living radical polymerization was employed to graft poly(stearyl methacrylate-co-2methacryloxyethyl phosphorylcholine) brushes onto the nanofibrils, and then 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation was conducted to produce nanoscale ACNCs in the aqueous solution. The ACNCs displayed interfibril association driven by the hydrophobic interaction that resulted in the formation of a nanofibrillar crystalline gel phase. We observed that the viscosity of the ACNC fluid showed reversible shear thinning and temperature-induced thickening in response to applied shear stress and thermal shock. Moreover, thanks to generation of a mechanically robust nanofibrillar crystalline gel network, the ACNC suspension showed extraordinary stability to changes in salinity and pH. These results highlighted that the interfibril hydrophobic association of ACNCs was vital and played an essential role in regulation of stimulireVonsive sol gel transitions.</P>