Effect of Deposition Potential and Bath Temperature on One-Step Electrochemical Synthesis of One and Two Dimensional Nanostructured ZnO Thin Films on Fluorine Doped Tin Oxide Substrates.

Different zinc oxide (ZnO) morphologies such as platelets, nanowalls and nanorods were electrochemically synthesized on fluorine doped tin oxide (FTO) substrates by varying the deposition potentials and bath temperatures, respectively. Cyclic voltammetry (CV) curves reveal that ZnO deposition potentials are decreased as the bath temperatures are increased. X-ray diffraction (XRD) patterns and transmission electron microscope (TEM) images confirm that the synthesized ZnO nanostructures are hexagonal wurtzite structure. The XRD results reveal that the crystallinity of the films is increased when ZnO deposition potentials and temperatures are increased. Field emission scanning electron microscope (FE-SEM) images display platelets, nanowalls and nanorods structures for films synthesized -1.1 V, -1.2 V and -1.3 V respectively. The increase in deposition potential not only increases the growth rate of ZnO with metallic zinc deposition, but also decreases zinc hydroxide chloride hydrate. Fourier transform infrared microscope (FTIR) spectra confirm that the formation of zinc hydroxide (Zn(OH)2) is decreased as the bath temperatures are increased from 30 to 70 °C. Photoluminescence (PL) spectra depict that the crystal quality of the ZnO films are notably improved as the bath temperatures are increased. The film thickness is increased as the deposition potentials and bath temperatures are increased. The dye absorbance is increased with respect to the film thickness. The efficiencies of dye sensitized solar cells (DSSCs) fabricated with diverse morphologies such as platelets, nanowalls and nanorods are found to be 0.10, 0.49 and 0.47%, respectively. Electrochemical impedance spectroscopy (EIS) spectra reveal that the charge transfer recombination resistance (Rrec) is continuously decreased as metal zinc deposition is increased in ZnO films with increase in deposition potentials.

Role of Annealing Temperatures on Mechanical, Optical, Electrical and Magnetic Properties of Nanohydroxyapatite Biomaterial.

Nanosized hydroxyapatite [Ca10(Po4)6(OH)2 or HAp] was prepared by applying wet-chemical precipitation technique. Thermogravimetric and Differential Scanning Calorimetry (TG/DSC) analyses, showed that the prepared sample was stable up to 919.2 °C. X-ray diffraction (XRD) pattern showed that as-prepared and annealed samples are in hexagonal structure. The average crystallite size is found to be 39, 46, 51 and 65 nm for the as-prepared, 700, 800 and 900 °C annealed HAp respectively. The dislocation density, strain and surface area were decreased with increase in annealing temperature. FT-IR and Raman spectra showed both as-prepared and annealed samples having characteristic bands of HAp. FE-SEM and TEM images which depicted and confirmed the hexagonal structure of HAp. The optical band gap calculated from the UV absorption behavior of as-prepared and annealed at 700, 800 and 900 °C HAp are 3.86, 3.84, 3.54, and 3.03 eV respectively. As the annealing temperature increases, the conductivity decreases whereas the impedance increases. The ac conductivity of as-prepared and annealed samples are in the order of 10-5 Sm-1. The VSM analysis confirmed that both as-prepared and annealed samples of HAp are in diamagnetic nature. The antibacterial activity of apatite samples depend on the types of bacterial strains and also their activity changed with the crystallite size.

Synthesis and biocompatibility of dual-responsive thermosonic injectable organogels based on crosslinked N-(isopropyl acrylamide) for tumour microenvironment targeting.

A series of three dual-responsive 'thermosonic' (thermo- and ultrasound-responsive) injectable organogels (TIOs) based on crosslinked N-(isopropyl acrylamide) (NIPAM) bearing biocompatible polymeric constituents were investigated for strong gelation in response to tumour temperature, and sol-like fluid gel formation upon the application of an ultrasonic stimulus. A time-efficient free radical polymerisation reaction of ˂15 min resulted in TIO formation. Moreover, the formulation of the TIOs integrated green chemistry principles to ensure enhanced biocompatibility. Fourier Transform Infrared (FTIR) spectral analysis revealed the presence of new molecular vibrations at 847 and 771 cm-1 (CH deformation), which were indicative of the functionalisation of the NIPAM backbone with hydrophobic and ultrasound-responsive aromatic moieties. Thermo- and ultrasound-response analysis and rheological analysis demonstrated that the TIOs displayed a temperature-induced transition to a strong highly-structured gel, and an ultrasound-triggered increase in gel flowability dependant on the composition of the formulation. Cell proliferation studies were undertaken for the TIOs, which verified that the designed TIOs were all non-cytotoxic and promoted cell proliferation over 1, 3, and 5 day intervals. The rational design and formulation of a biocompatible injectable in-situ depot drug delivery system for ultimate application in tumour targeting was successfully achieved and warrant further investigation.

Structural basis for complementary and alternative medicine: Phytochemical interaction with non-structural protein 2 protease-a reverse engineering strategy.

OBJECTIVE: To understand the druggability of the bioactive compounds from traditional herbal formulations "Nilavembu Kudineer" and "Swasthya Raksha Amruta Peya" to heal chikungunya virus (CHIKV) infection. METHODS: The efficiency of twenty novel chemical entities from "Nilavembu Kudineer" and "Swasthya Raksha Amruta Peya" to inhibit CHIKV infection in silico were evaluated. Ligands were prepared using Ligprep module of Schrödinger. Active site was identified using SiteMap program. Grid box was generated using receptor grid generation wizard. Molecular docking was carried out using Grid Based Ligand Docking with Energetics (GLIDE) program. RESULTS: Molecular docking studies showed that among twenty compounds, andrographoside, deoxyandrographoside, neoandrographolide, 14-deoxy-11-oxoandrographolide, butoxone and oleanolic acid showed GLIDE extra precision (XP) score of -9.10, -8.72, -8.25, -7.38, -7.28 and -7.01, respectively which were greater than or comparable with chloroquine (reference compound) XP score (-7.08) and were found to interact with the key residues GLU 1043, LYS 1045, GLY 1176, LEU 1203, HIS 1222 and LYS 1239 which were characteristic functional unit crucial for replication of CHIKV. CONCLUSION: The binding affinity and the binding mode of chemical entities taken from herbal formulations with non-structural protein 2 protease were understood and our study provided a novel strategy in the development and design of drugs for CHIKV infection.

Differences in the regional prevalence of chronic hepatitis B in southern Africa--implications for vaccination.

Chronic hepatitis B infection is an important cause of cirrhosis and subsequent hepatocellular carcinoma in South Africa. The disease can now be prevented by vaccination, but second-generation genetically engineered vaccines still necessitate planned allotment. We have tested 29,312 black southern African mineworkers for hepatitis B surface antigen (HBsAg) to indirectly ascertain the relative prevalence of hepatitis B infection in diverse linguistic and ethnic groups. The overall prevalence of HBsAg in this cohort of predominantly rural men was 9.9%, but the prevalence in men from different regions varied from 5.5% to 14%. The relative prevalence in 200 magisterial districts was ranked; these percentage prevalences ranged from 0% to 17%. A significantly lower mean prevalence was detected in Southern Sotho subjects than in those from coastal districts (Nguni). Based on these data, we believe that there are perhaps 2 million hepatitis B carriers in South Africa. The collected data in this report could provide a basis for a broad-based vaccine campaign whereby hepatitis B vaccine could be targeted to high-priority districts initially. This strategy could rapidly reduce the critical mass of carriers, and hasten control of the disease.

Regional prevalence of hepatitis B, delta, and human immunodeficiency virus infection in southern Africa: a large population survey.

Although hepatitis B infection is endemic in southern Africa, a changing epidemiology of the disease has recently been documented in the region. The authors surveyed migrant southern African male mineworkers during 1986 to establish the prevalence of chronic hepatitis B and D (delta) infection in their areas of origin. Hepatitis B surface antigen (HBsAg) was tested in 29,312 adult male mineworkers from 18 geographic regions, encompassing the diverse tribal and linguistic groups in the region, as well as in expatriate mineworkers from neighboring southern African countries. The same cohort was also tested for antibody to human immunodeficiency virus (HIV). Selected hepatitis B carriers were also tested for hepatitis B virus deoxyribonucleic acid (DNA), antibody to hepatitis D (anti-HD), and alpha-fetoprotein. The overall prevalence of HBsAg in this survey was 9.9%. However, the prevalence varied from 5.5% to 14% in different ethnic groups. A minority of carriers (4.9%) had replicative hepatitis B infection and were hepatitis B virus DNA-positive. Only 0.6% of tested carriers were anti-HD-positive. Alpha-fetoprotein determinations were abnormal in 1.2% of hepatitis B-positive men. These data show that although chronic hepatitis B infection remains widespread in southern Africa, carrier rates vary significantly from region to region. In contrast, hepatitis D co-infection remains extremely uncommon. These baseline seroprevalence data also establish that HIV infection was, in 1986, a rare infection in the indigenous population of South Africa.

The interpretation of ELISA results by means of the standard deviation ratio.

An improved sensitivity to low levels of hepatitis B surface antigen (HBsAg) was demonstrated when ELISA results were interpreted by a statistical method. The absorbance of each test well was compared with the mean absorbance of all low-colour test samples. Those wells with an absorbance of more than two standard deviations above the mean were referred for confirmatory tests. Samples containing 1.0 ng/ml of HBsAg were reliably detected by a rapid assay technique (1.5 h). Predictive value analysis showed greater sensitivity than was possible from a direct comparison of test samples with controls.

Safer blood--supplementation of blood products with anti-HBs.

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection and quantitation of antibodies (anti-HBs) to the surface antigen of the hepatitis B virus (HBsAg). The ELISA uses HBsAg as the solid phase, and, after conjugation to horseradish peroxidase, also as the conjugate. Conditions for this assay were optimized and a rapid (1.5 hours) ELISA has evolved which works very satisfactorily for the large-scale screening of donated blood. We have used this ELISA to examine donated blood in Natal and concluded that we cannot initiate a programme of anti-HBs supplementation of parenteral blood products without hyperimmunization and plasmapheresis of selected, voluntary donors.

Mouse monoclonal anti-HBs and its use in the screening of donated blood by Elisa.

A method is described for the production of mouse monoclonal antibodies to HBsAg. 4 clones produced antibodies directed at the a and one at the d determinant of HBsAg. These antibodies were conjugated to horse radish peroxidase and used in an Elisa for the detection of HBsAg in donated blood. Antibody C10 produced conjugate which rendered the Elisa as sensitive as a commercially obtainable immunoradiometric assay with which it was compared. Conditions for this assay were optimised and it may be used as a rapid (1 h) test for detecting HBsAg-positive blood. It is practicable to read this Elisa by eye instead of photometrically and it can be thus used under field conditions or in emergencies.

Hepatitis B surface antigen in donated blood--screening and confirmation by enzyme-linked immunosorbent assay.

Principles of and test procedures enzyme-linked immunosorbent assay (ELISA) screening and confirmatory tests for hepatitis B surface antigen (HBsAg) in donated blood are described. The assay is of "third-generation' sensitivity and is practical and economical for large-scale screening of blood donors. Results from 119,000 tests show ELISA to be superior to the passive haemagglutination inhibition (PHAI) test for HBsAg. The ELISA described here is considerably cheaper than any comparable commercially available isotopic kit for HBsAg screening but is slightly less sensitive.

Hepatitis B antigen and antibodies in rural and urban Southern African blacks.

Random samples which represented Blacks living in an urban area (Durban) and a rural area (Transkei) of the east coast of southern Africa were investigated for the incidence and distribution of hepatitis B antigen and antibodies. The overall prevalence of carriers of the virus was higher in rural communities (15,5%) than in the urban population (7,4%). In adults the formation of antibodies to the virus correlated with the pattern of increased activity of the hepatitis B carrier. Similar correlations could not be made for children living in the rural area. Of significance was the observation that the high carrier rate of the virus (17%) was more often associated with a reduced development of antibodies to the virus. Evidence for a depressed immunity and inability to make hepatitis B antibodies in these children is thought to be linked with the high prevalence of other forms of endemic infections, particularly acute measles.

Hepatic infections. Part II. The effect of acute and chronic hepatitis B antigenaemia on the reaction to antibodies to sheep red cells (microbial antigens) and human T-activated cells (exposed autologous tissue antigens).

Using the agglutination of sheep red cells by human antibodies as an indicator of microbial antibody activity, a highly significant association was found between the response to the e antigen of the hepatitis B virus and the formation of strong antibody levels to microbial substances (chi 2(1) = 33). This kind of association was not found among chronic carriers of the hepatitis B virus who do not produce antibodies to the e antigen (chi 2(1) = 3,7). In the presence of e antigen activity, patients with acute virus B hepatitis almost always show significantly reduced levels of antibodies to microbial substances (chi 2(1) = 20). The findings indirectly reveal that e activity is associated with the inability of the liver to trap bacterial antigens. Circumstantial evidence further suggests that the e factor may bear antigens on its immunoglobulin-like structure very similar to microbial cell wall components. Accepting that human antibodies to the T (Thomsen-Friedenreich) antigen represent reactions to cryptantigenic membrane structure of autologous tissues, it was significant to record that increased anti-t activity is always demonstrated when virus B infections progress from the acute to the chronic carrier stage (chi 2(1) = 73). The most intense anti-T activity is commonly found in subjects who produce antibodies to the hepatitis B surface antigen (chi 2(1) = 138). In the presence of e antigen the amount of anti-T in circulation is always significantly depressed. Since this type of depression is not seen in patients with acute virus B hepatitis who lack the e antigen, we suspect that the reduced anti-T levels in e antigen-positive patients are linked with the in vivo exposure of T receptors by microbial neuraminidase.

Hepatic infections. Part I. A serological evaluation of Fab antigens (Fab' and F (ab)2) and antibodies in patients and asymptomatic carriers of hepatitis B virus.

Evidence for the association of Fab (antigen-binding) fragments of IgG and antibodies directed against receptors of these fragments (Fab' and F(ab)2) has been found in patients and asymptomatic carriers of hepatitis B antigen. Fab fragments of IgG are often detected in hepatitis B surface antigen (HBsAg)-positive sera where the intensity of antibody activity to these determinants is significantly reduced. The formation of strong antibodies to Fab fragments is often observed in association with the presence of hepatitis B surface antibodies (HBsAb). Comparative studies show that the appearance of Fab fragments in HBsAg-positive sera is not linked to the presence of hepatitis e antigen. This observation was supported by the finding of autologous Fab fragments of IgG in e antibody-positive sera. It was also established that the amount of Fab fragment in the serum is closely associated with the detection of high HBsAg titres. Preliminary investigations suggest that the Fab fragments of IgG detected in the serum of HBsAg-positive patients represent in vivo-digested HBsAb attached to the surface membrane of virus B particles. Further studies are in progress to determine the relationship of Fab fragments with a variety of other immunological events, especially the role of liver enzymes in the cleavage of intact antibodies.

Heterophile antibodies. Part III. Evidence for linkage of high responder activity to sheep red blood cells and the formation of specific antibodies to HBsAg.

Group A, B and O subjects who produce immune antibodies to group A1 or B red blood cells also produce high titer antibodies to sheep red blood cells. Sheep red blood cells appear to possess AB-like as well as non-AB determinants on their surface membranes, each capable of producing and reacting with antibodies of their respective specificities. The antibodies against AB-like determinants preferentially agglutinate A or B cells whereas non-AB-like determinants preferentially stimulate hemolytic antibodies. Human antibodies reacting with these two kinds of determinants on sheep red blood cells may be produced in response to microorganisms possessing very similar factors on their membranes. Individuals who possess AB-like determinants in their secretions, similar to the determinants present on sheep red blood cells (or microorganisms), often make weaker antibodies to these red blood cells. Subjects lacking corresponding anti-sheep inhibitors in their secretions generally produce stronger sheep red blood cell antibodies. There is a positive correlation between the formation of antibodies to HBsAg and strong agglutinating antibodies to sheep red blood cells, indicating that similar determinants may be found on HBsAg virus and on sheep red blood cells. No such correlation was found for anti-tetanus antibodies.

Hemagglutination inhibiton in capillary tubes--a simple and reliable test for HBsAg.

A technique is described which allows testing for HBsAg by hemagglutination inhibition in capillary tubes. The test is rapid, and compares favorably in sensitivity to radioimmunoassay. The equipment is simple, and its design eliminates the risk of infection from the HBsAg reagents.

A correlation between the dissipation of insecticides and rhizosphere microflora of Abelmoschus esculentus (L.) Moench.

A study to understand the relationship between the dissipation of aldicarb and disulfoton in the rhizosphere region of bhendi and the microbial population revealed a negative correlation between the fungal and Azotobacter population and the residues of both insecticides. However, no definite correlation could be recorded between the populations of bacteria and actinomycetes and the residues of the insecticides.