Amelanotic Melanoma in the Vicinity of Acquired Melanocytic Nevi and not Arising from Agminated Melanocytic Nevi: Masquerading as Pyogenic Granuloma.

Amelanotic melanoma (AMM) presenting as pyogenic granuloma and occurring in the vicinity of acquired melanocytic nevi is rare. Herein, we report such a manifestation in a 68-year-old male who presented with the painful red nodule and multiple pigmented patches involving the left great toe. Histopathological examination of skin biopsy taken from the nodule with an immunohistochemical study using HMB45 and S-100 confirmed the diagnosis of AMM. Biopsy from the pigmented patch near the nodule showed features of melanocytic nevus. Investigative work up revealed metastatic deposits in the left inguinal lymph node with no evidence of systemic involvement, placing him in malignant melanoma Stage IIIC of American Joint Committee on Cancer (AJCC) tumor node metastasis system. The development of AMM in the vicinity of acquired melanocytic nevi and manifesting as granuloma pyogenicum is unique in this case.

Improved photovoltaic performance and stability of quantum dot sensitized solar cells using Mn-ZnSe shell structure with enhanced light absorption and recombination control.

To make quantum-dot-sensitized solar cells (QDSSCs) competitive, photovoltaic parameters comparable to those of other emerging solar cell technologies are necessary. In the present study, ZnSe was used as an alternative to ZnS, one of the most widely used passivation materials in QDSSCs. ZnSe was deposited on a TiO2-CdS-CdSe photoanode to form a core-shell structure, which was more efficient in terms of reducing the electron recombination in QDSSCs. The development of an efficient passivation layer is a requirement for preventing recombination processes in order to attain high-performance and stable QDSSCs. A layer of inorganic Mn-ZnSe was applied to a QD-sensitized photoanode to enhance the adsorption and strongly inhibit interfacial recombination processes in QDSSCs, which greatly improved the power conversion efficiency. Impedance spectroscopy revealed that the combined Mn doping with ZnSe treatment reduces interfacial recombination and increases charge collection efficiency compared with Mn-ZnS, ZnS, and ZnSe. A solar cell based on the CdS-CdSe-Mn-ZnSe photoanode yielded excellent performance with a solar power conversion efficiency of 5.67%, Voc of 0.584 V, and Jsc of 17.59 mA cm(-2). Enhanced electron transport and reduced electron recombination are responsible for the improved Jsc and Voc of the QDSSCs. The effective electron lifetime of the device with Mn-ZnSe was higher than those with Mn-ZnS, ZnSe, and ZnS, leading to more efficient electron-hole separation and slower electron recombination.

Cost-effective and morphology controllable PVP based highly efficient CuS counter electrodes for high-efficiency quantum dot-sensitized solar cells.

Currently, copper sulfide (CuS) is the most commonly used counter electrode (CE) in high-efficiency quantum dot-sensitized solar cells (QDSSCs) because of its superior electrocatalytic activity in the presence of polysulfide electrolyte. For the first time, CuS thin films were prepared by a facile chemical bath deposition method with different concentrations of polyvinylpyrrolidone (PVP) and directly used as CEs in QDSSCs without any further post treatment. The quantum dot photoanode with the optimized 0.25 mM PVP-based CuS CE exhibits higher short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF), and power conversion efficiency (PCE) of 17.57 mA cm(-2), 0.578 V, 0.514, and 5.22%, respectively, which are much higher values than those of a bare CuS CE (Jsc: 12.36 mA cm(-2); Voc: 0.591 V; FF: 0.436; PCE: 3.18%) and Pt CE (Jsc: 11.25 mA cm(-2); Voc: 0.464 V; FF: 0.296; PCE: 1.54%) under one-sun illumination (AM 1.5 G, 100 mW cm(-2)). Moreover, the 0.25 mM PVP-based CuS CE produces a charge-transfer resistance of only 4.39 Ω with the aqueous polysulfide electrolyte commonly applied in QDSSCs. This value is several orders of magnitude lower than that of a typical Pt electrode (69.75 Ω) and bare CuS electrode (9.27 Ω). This enhancement is mainly attributed to the improved morphology of the 0.25 mM CuS CE with high catalytic activity, which plays a main role in the reduction processes of the oxidized polysulfide electrolyte, as well as the increased sulfur atomic percentage with Cu vacancies. Cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization were performed to study the underlying reasons behind the efficient CE performance.

A strategy to improve the energy conversion efficiency and stability of quantum dot-sensitized solar cells using manganese-doped cadmium sulfide quantum dots.

This article describes the effect of manganese (Mn) doping in CdS to improve the photovoltaic performance of quantum dot sensitized solar cells (QDSSCs). The performances of the QDSSCs are examined in detail using a polysulfide electrolyte with a copper sulfide (CuS) counter electrode. Under the illumination of one sun (AM 1.5 G, 100 mW cm(-2)), 10 molar% Mn-doped CdS QDSSCs exhibit a power conversion efficiency (η) of 2.85%, which is higher than the value of 2.11% obtained with bare CdS. The improved photovoltaic performance is due to the impurities from Mn(2+) doping of CdS, which have an impact on the structure of the host material and decrease the surface roughness. The surface roughness and morphology of Mn-doped CdS nanoparticles can be characterised from atomic force microscopy images. Furthermore, the cell device based on the Mn-CdS electrode shows superior stability in the sulfide/polysulfide electrolyte in a working state for over 10 h, resulting in a highly reproducible performance, which is a serious challenge for the Mn-doped solar cell. Our finding provides an effective method for the fabrication of Mn-doped CdS QDs, which can pave the way to further improve the efficiency of future QDSSCs.

Formulation and evaluation of niosomal nasal drug delivery system of folic acid for brain targeting.

Nasal mucosa offers advantages to deliver drugs to brain via olfactory route thus provides rapid onset of drug action and hence faster therapeutic effect. Therefore, various strategies have been proposed to improve the delivery of different drugs to brain including liposomes, colloidal drug carriers, micelles, chimeric peptide technology and nanotechnology through nasal route. The low blood level of folates is the primary cause of depression in Alzheimer's disease. Folic acid is a water soluble vitamin showing difficulty in crossing the blood brain barrier and thus was formulated as niosomal nasal drug delivery systems to target the brain. In the present work, folic acid niosomes were prepared using different nonionic surfactants i.e., span 20, span 60, span 80, tween 20, tween 80 and cholesterol by using lipid layer hydration technique. These were evaluated for particle size, viscosity, osmotic shock, entrapment efficiency and in vitro drug release. The influence of different formulation variables such as surfactant type, surfactant concentration, and cholesterol concentration was optimized for required size distribution, viscosity, entrapment efficiency and in vitro release. The prepared niosomes were in the size range of 3.05-5.625 µm. Niosomes prepared with span 60 and cholesterol in the ratio of 1:1 (50 mg: 50 mg) shown higher entrapment efficiency of 69.42% and better in vitro drug release of 64.2% at the end of 12 hrs and therefore considered as optimized formulation. The stability studies were carried out by storing niosomes at 4±1°C and 25±1°C and showed good stability over the period of storage. The release of drug from niosomes followed anomalous diffusion and obeyed first order release kinetics. Ex-vivo perfusion studies were also performed by using rat model, about 48.15% of drug was found to be absorbed through nasal cavity at the end of 6 hrs.