Two electrodeposition strategies for the morphology-controlled synthesis of cobalt nanostructures

In this contribution, two different strategies are discussed to synthesize cobalt nanostructures: direct cobalt electrodeposition on a planar aluminum electrode and cobalt electrodeposition into nanoporous alumina templates generated by aluminum anodization (template electrodeposition). In the direct electrodeposition of cobalt on aluminum, cobalt nanoparticles are formed during the early stage of electrodeposition, which causes the depletion of cobalt ions near the electrode. Water reduction then takes place catalyzed by electrodeposited cobalt nanoparticles, which increases the pH near the electrode and can induce cobalt hydroxide precipitation. By varying the electrode potential and the cobalt ion concentration, the interplay between electrochemical growth of cobalt and water reduction could be controlled to induce transition from cobalt hexagonal nano-platelets to nanostructured films composed of cobalt nanoparticles and cobalt hydroxide nano-flakes. Cobalt nanowires can be synthesized by electrodeposition into nanoporous alumina templates generated by aluminum anodization. This approach typically involves the application of alumina templates produced by a two-step anodization procedure: the alumina nanoporous layer generated by a first anodization is dissolved in a chromic acid solution while a very ordered alumina nanoporous layer is produced by a second anodization stage. In accordance with previous studies, this procedure is fundamental to achieve uniform filling of the nanopores in the subsequent electrodeposition stage. In the present study, uniform filling of the nanoporous alumina generated by one-step anodization could be achieved by the electrodeposition of cobalt nanowires. This result was made possible by the application of a novel pulsed electrodeposition strategy

Municipal Treated Wastewater Irrigation: Microbiological Risk Evaluation

Municipal wastewater for irrigation, though treated, can contain substances and pathogens toxic for humans and animals. Pathogens, although not harmful from an agronomical aspect, undoubtedly represent a major concern with regards to sanitary and hygienic profile. In fact, vegetable crops irrigated with treated wastewater exalt the risk of infection since these products can also be eaten raw, as well as transformed or cooked. Practically, the evaluation of the microbiological risk is important to verify if the microbial limits imposed by law for treated municipal wastewater for irrigation, are valid, thus justifying the treatments costs, or if they are too low and, therefore, they don' t justify them. Different probabilistic models have been studied to assess the microbiological risk; among these, the Beta-Poisson model resulted the most reliable. Thus, the Dipartimento di Scienze delle Produzioni Vegetali of the University of Bari, which has been carrying out researches on irrigation with municipal filtered wastewater for several years, considered interesting to verify if the microbial limits imposed by the italian law n.185/03 are too severe, estimating the biological risk by the probabilistic Beta-Poisson model. Results of field trials on vegetable crops irrigated by municipal filtered wastewater, processed by the Beta-Poisson model, show that the probability to get infection and/or illness is extremely low, and that the actual italian microbial limits are excessively restrictive

TOXICITY OF PREDNISOLONE, DEXAMETHASONE AND THEIR PHOTOCHEMICAL DERIVATIVES ON AQUATIC ORGANISMS

Light exposure of aqueous suspensions of prednisolone and dexamethasone causes their partial phototransformation. The photoproducts, isolated by chromatographic techniques, have been identified by spectroscopic means. Prednisolone, dexamethasone and their photoproducts have been tested to evaluate their acute and chronic toxic effects on some freshwater chain organisms. The rotifer Brachionus calyciflorus and the crustaceans Thamnocephalus platyurus and Daphnia magna were chosen to perform acute toxicity tests, while the alga Pseudokircheneriella subcapitata (formerly known as Selenastrum capricornutum) and the crustacean Ceriodaphnia dubia to perform chronic tests. The photochemical derivatives are more toxic than the parent compounds. Generally low acute toxicity was found. Chronic exposure to this class of pharmaceuticals caused inhibition of growth population on the freshwater crustacean C. dubia while the alga P. subcapitata seems to be less affected by the presence of these drugs

Highly Isotactic Poly(N-butenyl-carbazole): Synthesis, Characterization, and Optical Properties

The synthesis of isotactic poly(N-butenyl-carbazole) (i-PBK) by using homogeneous isospecific Ziegler-Natta catalytic system is reported. The achieved polymer is crystalline and shows, to DSC and X-ray analysis, two distinct crystalline phases.i-PBK FTIR spectrum and X-ray diffraction pattern are compared with those of poly(N-vinylcarbazole) (PVK). The observed differences are tentatively associated with higher flexibility of thei-PBK chains due to the alkylene group connecting the carbazole group to the main chain.i-PBK optical properties are also compared with those of PVK and isotactic poly(N-pentenyl-carbazole) (i-PPK), a higher homologue ofi-PBK recently used as emitting layer in organic light emitting diodes (OLEDs) showing white light emission. The close similarity of the fluorescence spectra ofi-PBK andi-PPK is a promising basis for optical applications of this polymer

Location of actin, myosin, and microtubular structures during directed locomotion of <i>Dictyostelium amebae</i>

During their life cycle, amebae of the cellular slime mould Dictyostelium discoideum aggregate to form multicellular structures in which differentiation takes place. Aggregation depends upon the release of chemotactic signals of 3',5'-cAMP from aggregation centers. In response to the signals, aggregating amebae elongate, actively more toward the attractive source, and may be easily identified from the other cells because of their polarized appearance. To examine the role of cytoskeletal components during ameboid locomotion, immunofluorescence microscopy with antibodies to actin, myosin, and to a microtubule-associated component was used. In addition, rhodamine- labeled phallotoxin was employed. Actin and myosin display a rather uniform distribution in rounded unstretched cells. In polarized locomoting cells, actin fluorescence (due to both labeled phallotoxin and specific antibody) is prevalently concentrated in the anterior pseudopod while myosin fluorescence appears to be excluded from the pseudopod. Similarly, microtubules in locomoting cells are excluded from the leading pseudopod. The cell nucleus is attached to the microtubule network by way of a nucleus-associated organelle serving as a microtubule-organizing center and seems to be maintained in a rather fixed position by the microtubules. These findings, together with available morphological and biochemical evidences, are consistent with a mechanism in which polymerized actin is moved into the pseudopod through its interaction with myosin at the base of the pseudopod. Microtubules, apparently, do not actively participate in movement but seem to behave as anchorage structures for the nucleus and possibly other cytoplasmic organelles

Desafíos de la gerencia y el liderazgo de la educación superior

Este trabajo es el producto de una modesta revisión de la literatura sobre algunas tendencias actuales en la gerencia y el liderazgo que, en el contexto latinoamericano, han estado guiadas por un enfoque reduccionista, basadas en una preparación gerencial positivista, que no ha permitido verlas como un proceso sistémico, con múltiples relaciones con el entorno y la sociedad. La gerencia y el liderazgo en el nivel superior deben desenvolverse en cuatro áreas fundamentales. No obstante, en la práctica, estas áreas están interrelacionadas, y la definición de sus límites se hace sumamente difusa. Ellas incluyen el liderazgo con elementos propios de la organización y del entorno, la adopción y desarrollo de las infraestructuras, la planificación estratégica basada en el análisis del entorno y la alineación organizacional. Se concluye que la puesta en práctica de las mismas está íntimamente relacionada con competencias, valores y principios que los líderes deben poseer y practicar

Ti/TiO2/Cu2O electrodes for photocatalytic applications: synthesis and characterization

Energy from renewables (solar, photovoltaic, geothermal), is a major challenge for researchers' efforts in reason of the intermittent nature of these energy sources. Systems like photoelectrochemical (PEC) cells are promising devices that allow the direct conversion of solar energy into electric power and/or chemical fuels. The direct conversion of solar energy in fuels can be achieved using photocatalysts, based on semiconductors like TiO2. In this work TiO2 nanotubes were achieved through “one-step” anodization of titanium, a low cost and accurate method which allowed to control dimensions and morphology of the nanostructured Ti/TiO2 electrodes. Central limit for TiO2 photoconversion efficiency is its wide bandgap (i.e. a3.2eV), which limits light absorption to the ultraviolet region (3-5% of the solar radiation). Composite Cu2O/TiO2 systems have attracted much attention: Cu2O is a promising semiconductor material (bandgap 2.0-2.6eV), suitable to absorb visible light. Traditionally, Cu2O deposition techniques include the impregnation of TiO2 with a copper salt and subsequent calcination, but offers little control on sizes, shape and deposit's composition. In this work we developed an electrodeposition method in order to control Cu2O morphology and sizes in the composed Ti/TiO2/Cu2O electrodes

Primary dermal melanoma in a patient with a history of multiple malignancies: a case report with molecular characterization

Introduction: Primary dermal melanoma (PDM) is a recently described clinical entity accounting for less than 1% of all melanomas. Histologically, it is located in the dermis or subcutaneous tissue, and it shows no connections with the overlying epidermis. The differential diagnosis is principally made along with that of metastatic cutaneous melanoma. Case Report: A 72-year-old Caucasian woman with a history of multiple cancers (metachro-nous bilateral breast cancer, meningioma, clear cell renal cell carcinoma, uterine fibromatosis and intestinal adenomatous polyposis), came to our attention with a nodular lesion on her back. After removal of the lesion, the histology report indicated malignant PDM or metastatic malignant melanoma. The clinical and instrumental evaluation of the patient did not reveal any other primary tumour, suggesting the primitive nature of the lesion. The absence of an epithelial component argued for a histological diagnosis of PDM. Subsequently, the patient underwent a wide surgical excision with sentinel node biopsy, which was positive for metastatic melanoma. Finally, the mutational status was studied in the main genes that regulate proliferation, apoptosis and cellular senescence. No pathogenetic mutations in CDKN2A, BRAF, NRAS, KRAS, cKIT, TP53 and PTEN genes were observed. This suggests that alternative pathways and low-frequency alterations may be involved. Conclusions: The differential diagnosis between PDM and isolated metastatic melanoma depends on the negativity of imaging studies and clinical findings for other primary lesions. This distinction is important because 5-year survival rates in such cases are higher than in metastatic cases (80– 100 vs. 5–20%, respectively)

Electrochemical pretreatments of carbon paper and their effect on the electrodeposition of metallic nanostructures

Gas diffusion electrodes (GDEs) represent a fundamental element for the development of gaseous electrochemical cells like water electrolysis reactors and fuel cells. Various technologies and materials are employed in order to obtain a conductive, stable and gas permeable structure. Among them, carbon-based structures such as carbon paper are widely used: their composition allows the diffusion of gaseous reagents and products and simultaneously does not permit the flooding of the gas-diffusion structure by aqueous electrolytes. However, the hydrophobicity of this material may represent a drawback to water-based electrode synthesis like galvanic deposition, and various chemical or thermal pretreatments were developed in the last decades. A new kind of pre-treatment based on electrical oxidation of the carbon paper surface is here described and evaluated. The electro-oxidative method allows a rapid and localized pre-treatment of the carbon paper, avoiding the use of highly reactive chemicals or long thermal treatments, reducing treatment wastes, time loss and electrical consumption. Surface wettability of the carbon paper before and after pretreatment was compared by contact angle analysis. Pre-treated and virgin carbon paper were subsequently electroplated from a copper deposition bath and deposition morphologies were compared, in order to establish the effect of the pre-treatment. Electroplated supports were analyzed by scanning electron microscopy (SEM) in order to analyze both micro and nanomorphology of the metallic structure

TiO2nanotubes in lithium-ion batteries

In this contribution we report on electrochemical approaches in TiO2 based electrodes synthesis. TiO2 nanotubes (NTs) were synthesized following a facile anodization of titanium sheets. Optimizing the experimental conditions two electrodes with NTs lengths of ∼10 μm (Long) and ∼2 μm (Short), were obtained. At the end of the anodization the amorphous TiO2 (a-TiO2) was thermally treated to promote the conversion in the anatase crystal phase (c-TiO2). Both the Long and Short NTs electrodes were tested for their applications as anodes in lithium-ion batteries (LIBs). A preliminary comparison was performed to evaluate the role of a-TiO2 and c-TiO2 phases. Here, Short a-TiO2 NTs exhibited a fast storage rate respect to Short c-TiO2. Comparing the NTs length, Long a-TiO2 electrodes exhibited the highest specific capacity, close to the theoretical value. Furthermore, all the electrodes tested showed an excellent capacity retention proceeding with Discharge/Charge cycles