Synergistic effect of Ni–Ag–rutile TiO2 ternary nanocomposite for efficient visible-light-driven photocatalytic activity

P25 comprising of mixed anatase and rutile phases is known to be highly photocatalytically active compared to the individual phases. Using a facile wet chemical method, we demonstrate a ternary nanocomposite consisting of Ni and Ag nanoparticles, decorated on the surface of XTiO₂ (X: P25, rutile (R)) as an efficient visible-light-driven photocatalyst. Contrary to the current perspective, RTiO₂-based Ni–Ag–RTiO₂ shows the highest activity with the H₂ evolution rate of ∼86 μmol g⁻¹ W⁻¹ h⁻¹@535 nm. Together with quantitative assessment of active Ni, Ag and XTiO₂ in these ternary systems using high energy synchrotron X-ray diffraction, transmission electron microscopy coupled energy dispersive spectroscopy mapping evidences the metal to semiconductor contact via Ag. The robust photocatalytic activity is attributed to the improved visible light absorption, as noted by the observed band edge of ∼2.67 eV corroborating well with the occurrence of Ti³⁺ in Ti 2p XPS. The effective charge separation due to intimate contact between Ni and RTiO₂via Ag is further evidenced by the plasmon loss peak in Ag 3d XPS. Moreover, density functional theory calculations revealed enhanced adsorption of H₂ on Ti₈O₁₆ clusters when both Ag and Ni are simultaneously present, owing to the hybridization of the metal atoms with d orbitals of Ti and p orbitals of O leading to enhanced bonding characteristics, as substantiated by the density of states. Additionally, the variation in the electronegativity in Bader charge analysis indicates the possibility of hydrogen evolution at the Ni sites, in agreement with the experimental observations.

Robust photocatalytic activity of Ni–Ag–RTiO₂ is attributed to the improved visible light absorption and effective charge separation due to intimate contact between Ni and RTiO₂via Ag, as evidenced by Ti³⁺ in Ti 2p XPS and energy dispersive mapping.     

Selective synthesis of visible light active γ-bismuth molybdate nanoparticles for efficient photocatalytic degradation of methylene blue,reduction of 4-nitrophenol,and antimicrobial activity

In this study, we have reported selective synthesis of bismuth molybdate (γ-Bi₂M₂O₆) nanoparticles (NPs) under different pH conditions for photocatalytic degradation of methylene blue (MB), reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) and antimicrobial activities. The synthesis of pure phase γ-Bi₂M₂O₆ at pH = 3 was confirmed by X-ray diffraction (XRD) and Raman analysis. A single hexagonal morphology was obtained at pH = 3 which shows the formation of the pure phase γ-Bi₂M₂O₆ NPs. The mixed morphologies (hexagonal and spherical) were observed at different pH values other than pH = 3. The bandgap energy of all the synthesized Bi₂M₂O₆ NPs is found in the visible region (2.48–2.59 eV). The photocatalytic activity of bismuth molybdate (BM) NPs was examined by the degradation of MB under visible light irradiation. Results show that 95.44% degradation efficiency was achieved by pure γ-Bi₂M₂O₆ NPs compared to mixed phases (γ-Bi₂M₂O₆, α-Bi₂M₂O₆ and β-Bi₂M₂O₆) synthesized at pH = 1.5 and 5. Moreover, the degradation efficiency of γ-Bi₂M₂O₆ was enhanced to 98.89% by the addition of H₂O₂. The effective catalytic activity of γ-Bi₂M₂O₆ was observed during the reduction of 4-NP to 4-AP by NaBH₄. Potential antibacterial and antifungal activity of γ-Bi₂M₂O₆ was observed, which gives a basis for further study in the development of antibiotics.

In this study, we have reported selective synthesis of γ-Bi₂M₂O₆ NPs under different pH conditions for photocatalytic degradation of methylene blue (MB), reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) and antimicrobial activities.     

Diagnosis of tuberculous meningitis: clinical and laboratory parameters.

BACKGROUND: Confirming the clinical suspicion of tuberculous meningitis (TBM) has always been problematic. Whilst smear and culture positivity are diagnostic, these tests have low sensitivity. The polymerase chain reaction (PCR) assay has given variable results. AIM: This study attempted to improve the diagnostic yield by: (a) increasing the cerebrospinal fluid (CSF) volumes; (b) testing the yield from three specimens of CSF assumed to represent lumbar, cervico-thoracic cord, and base of brain CSF samples; (c) undertaking PCR assays using multiple primer sets; and (d) using real-time PCR. METHOD: Patients suspected of having cranial or spinal meningeal tuberculosis were entered into the study. Three aliquots of CSF were subjected to smear, culture, and conventional and real-time PCR. Three sets of primers - IS6110, MPB64, and PT8/9 - were used. Patients were retrospectively classified into four categories: 'definite TB' (culture positive), 'probable TB' (clinical and other tests suggestive of TB), 'not TB', and 'uncertain diagnosis'. RESULTS: A total of 68 patients were studied. There were 20 patients classified as definite TB, 24 probable TB, 17 not TB, and seven uncertain diagnosis. Forty-eight of 57 (84.2%) patients tested were HIV seropositive. The IS6110 PCR was positive in 27 patients which included 18/20 culture positive cases, six in the probable TB group, and three in the not TB group. The MPB64 and PT8/9 primers did not increase the yield. Real-time PCR was positive in seven additional patients. Combining the definite and probable TB, the sensitivity of all PCR assays was 70.5% (31/44) and specificity 87.5% (21/24). CONCLUSION: Targeting multiple sites of the TB genome using conventional PCR did not increase the number of positive cases. Real-time PCR was more sensitive. However, all the current techniques are still too insensitive to confidently exclude the diagnosis on laboratory grounds.     

An overview of the endodontic curriculum in Fiji from 2009 to 2013

This paper seeks to provide the reader with an overview of the endodontic curriculum in Fiji from 2009 to 2013. It also intends to inform readers of the changes in endodontic teaching, the learning methods utilised, curriculum development, the transition from block teaching to partial block teaching combined with longitudinal teaching, and the future plans for the endodontic module.     

Prosthetic rehabilitation of an orbital and facial defect: a clinical report

For patients undergoing radical head and neck surgery, the deformity or physical defect adds to the agony. Rehabilitation of patients with such deformities is a challenge for the maxillofacial prosthodontist to enhance the esthetics and give psychological strength to the patient. This clinical report describes the rehabilitation, using a silicone prosthesis, of a large facial and orbital defect due to mucoepidermoid carcinoma.