Organic Single Crystal Patterning Method for Micrometric Photosensors

Light detection technologies are of interest due to their applications in energy conversion and optical communications. Single-crystal organic semiconductors, such as rubrene, present high detectivities and charge carrier mobility, making them attractive for light-sensing applications. Growth of high crystallinity organic crystals is achieved using vapor processes, forming crystals of arbitrary shapes and orientations and requiring posterior patterning processes. However, patterning the organic semiconductors using industry-standard microfabrication techniques is not straightforward, as these often cause irreversible damage to the crystals. Here the fabrication of patterned micrometric rubrene photosensors is demonstrated through a combination of photolithography and Reactive Ion Etching steps. Protective layers during microfabrication minimize degradation of optoelectronic properties of the organic single crystals during fabrication. Crystals undergoing the patterning process presented a survival rate of 39%. Photoresponse values of up to 41 mA W⁻¹ are obtained under illumination at 500 nm. This opens a route for the industrial-scale fabrication process of high-performance optoelectronic devices based on organic crystals semiconductors.     

Dilatometric behavior and microstructure of sintered Fe–NbC and Fe–TaC composites

Fe-reinforced composites were manufactured by the addition of 10–20 wt.% NbC or TaC particles aiming at improved mechanical and wear behavior. Two varieties of Fe powders from Hoeganaes Corp. were used, Ancorsteel 1000B and 45P. Composites produced using the former variety included a small amount of Fe₃P to induce liquid-phase sintering whereas 45P powder was pre-alloyed with P by the manufacturer. The hardness of the matrix was adjusted adding carbon to the composite mixture. The powders were milled for different times and annealed prior to pressing. A dilatometric study was carried out under hydrogen to establish optimum sintering profiles. Relative densities up to 97% TD were achieved. Both microstructure and density of the sintered pellets were evaluated in order to establish correlations involving composition, processing parameters and microstructure of the composite.     

Unusual case of disseminated sarcoidosis with prominent gastrointestinal symptoms

HISTORY AND ADMISSION FINDINGS: A 63-year-old man had for 10 months suffered from marked weight loss, night sweats, diffuse abdominal pain and increased stool frequency. He was admitted to evaluate an ultrasonically abnormal focus in the liver parenchyma and elevated liver function parameters. His sclerae were obviously icteric and he looked under-weight. INVESTIGATIONS: He had a hypochromic microcytic anemia and abnormal liver and pancreatic function tests: total bilirubin 3.11 mg/dl, direct bilirubin 2.21 mg/dl, GOT21U/l, gamma-GT 422 U/l, alkaline phosphatase 1449 U/l, alpha-amylase 481 U/l, lipase 2827 U/l. The serum creatinine level was elevated to 1.47 mg/dl. Computed tomography revealed enlarged liver and spleen as well as an enlargement of intraabdominal lymph nodes, chest radiogram and endoscopic cholangio-pancreatography were unremarkable. Biopsies from the lower duodenum, large intestine, bone marrow and liver showed inflammatory changes with Langhans-type mononuclear granulomas. Together with these findings an increased activity of the angiotensin-converting-enzyme (ACE) indicated sarcoidosis, other causes having been excluded. TREATMENT AND COURSE: All signs and symptoms rapidly improved under prednisolone, and 4 weeks after begin of treatment the biochemical abnormalities had clearly regressed. The raised serum levels of soluble IL-2 receptors and of neopterin, measures of sarcoidosis activity, had decreased. Activity of ACE had fallen. CONCLUSION: Sarcoidosis can present with diverse clinical signs and symptoms. In a case of multi-system disease that cannot be readily classified, sarcoidosis should be included in the differential diagnosis.     

The three-dimensional structure of human RNase 4, unliganded and complexed with d(Up), reveals the basis for its uridine selectivity

The RNase 4 family is unique among RNase enzymes, displaying the highest level of sequence similarity and encompassing the shortest polypeptide chain. It is the only one showing high specificity. The human representative is an intracellular and plasma enzyme, first isolated from colon adenocarcinoma cell line HT-29. The crystal structures of human recombinant RNase 4, unliganded and in complex with d(Up), have been determined, revealing in the unique active site an explanation for the uridine specificity. Arg101, at a position not involved in catalysis in the other RNase enzymes, penetrates the enzyme moiety shaping the recognition pocket, a flip that is mediated by the interaction with the (shorter chain) C-terminal carboxylate group, providing an anchoring point for the O4 atom of the substrate uridine. The bulky Phe42 side-chain forces Asp80 to be in the chi1=-72.49 degrees rotamer, accepting a hydrogen bond from Thr44, further converting the latter into a hydrogen bond acceptor. This favours an interaction with the -NH-donor group of uridine at position 3 over that with the =N-acceptor of cytidine. The two chemical groups that distinguish uracyl from cytosine are used by the enzyme to discriminate between these two bases.     

Heat-treated wood as chromium adsorption material

Heavy metals adsorption with lignocellulosic materials has been heavily researched in the last years. Since heat activation has been used with good results to increase the adsorption capacity of some materials, heat-treated wood might be a better adsorbent. This hypothesis is the basis of the present study. The adsorption tests were made with powdered pine wood, heat-treated at 190–210?°C. All the heat-treated samples showed a significantly higher adsorption compared to untreated wood. The maximum adsorption was obtained at pH 3 for heat-treated wood at 210?°C. The kinetics of the adsorption process fitted a pseudo-second-order reaction (R² 0.990–0.996). Adsorption fitted well both the Langmuir and the Freundlich model, but the Freundlich model presented higher R² (0.988–0.998). The q_max values estimated by the Langmuir plotting were in the range 15.6–19.4 mg/g and the n values from Freundlich isotherms between 1.87 and 2.39. Heat-treated wood was a better adsorption material than untreated wood for chromium adsorption. This can be a good application for the sawdust produced by the processing of heat-treated wood at primary and secondary wood processing mills or for the recycling of heat-treated wood at the end of product life.     

Inhibitory activity of plumbagin produced by Drosera intermedia on food spoilage fungi

BACKGROUND: The aim of this study was to investigate the growth‐inhibiting efficacy of Drosera intermedia extracts (water, methanol and n‐hexane) against four food spoilage yeasts and five filamentous fungi strains responsible for food deterioration and associated with mycotoxin production, in order to identify potential antimycotic agents. RESULTS: The n‐hexane extract showed a broad activity spectrum against all tested microorganisms, followed, in activity, by the methanol and water extracts. The major component of the n‐hexane extract was purified using a solid‐phase extraction column and identified as plumbagin. Results show that high‐purity plumbagin can be produced from D. intermedia cultures following a simple and effective isolation procedure. A sample of purified plumbagin was tested against the same panel of microorganisms and high growth‐inhibiting capacity was observed. Minimum inhibitory concentrations less than 2 µg mL^?1 were obtained against the filamentous fungi. In the case of the species Aspergillus fumigatus, A. niger and A. flavus , activities comparable to miconazole were obtained. CONCLUSION: The results obtained provided evidence of the antimycotic activity of plumbagin, suggesting that D. intermedia could be the source of an interesting compound for the food industry as an alternative to preservatives. Copyright © 2011 Society of Chemical Industry     

Texture and Porosity Effects on the Thermal Radiative Behavior of Alumina Ceramics

Thermal and optical properties of ceramics are dependent on radiation scattering and cannot be determined by a knowledge of their chemical composition alone, as for single crystals. In this paper, extrinsic effects, such as roughness, porosity, and texture, on the spectral emissivity of alumina ceramics are investigated. Roughness effects have an influence mainly in the opaque zone; an important porosity dependence and the presence of a critical porosity threshold were observed in the semitransparent zone. Furthermore, it was shown that two ceramics with similar total porosities, but with different textures, possess radically different emissivities, showing that grain size, pore size, and spatial repartition of the grains are also crucial for an understanding of the thermal properties of the ceramics. This study was performed at CEMTHI laboratory.     

Structural interaction of natural and synthetic inhibitors with the venom metalloproteinase, atrolysin C (form d)

The structure of the metalloproteinase and hemorrhagic toxin atrolysin C form d (EC 3.4.24.42), from the venom of the western diamondback rattlesnake Crotalus atrox, has been determined to atomic resolution by x-ray crystallographic methods. This study illuminates the nature of inhibitor binding with natural (< Glu-Asn-Trp, where < Glu is pyroglutamic acid) and synthetic (SCH 47890) ligands. The primary specificity pocket is exceptionally deep; the nature of inhibitor and productive substrate binding is discussed. Insights gained from the study of these complexes facilitate the design of potential drugs to treat diseases where matrix metalloproteinases have been implicated, e.g., arthritis and tumor metastasis.     

Cerebrospinal fluid cytokines in pediatric neuropsychiatric disease

This study examines cerebrospinal fluid from patients with three neuropsychiatric diseases of childhood for the presence and levels of several cytokines relevant to cell-mediated (type 1) and humoral (type 2) immunity. The patient groups include childhood-onset schizophrenia (n = 22), obsessive-compulsive disorder (OCD) (n = 24), and attention deficit hyperactivity disorder (n = 42). The cytokines examined include IL-2, IFN-gamma, TNF-beta/LT, IL-4, IL-5, IL-10, and TNF-alpha. Patients with OCD had a preponderance of type 1 cytokines. IL-4 was detectable only in samples from patients with schizophrenia. IL-10 was rarely detected and never in patients with OCD. Few patients with schizophrenia had detectable amounts of IFN-gamma in CSFL. We conclude that there is a relative skewing of CSFL profiles toward type 1 cytokines in patients with OCD, whereas in schizophrenia the relative preponderance is toward type 2 mediators. Patients with attention deficit hyperactivity disorder exhibited profiles intermediate between OCD and schizophrenia. We infer that cell-mediated immunity may be involved in the etiopathogenesis of OCD, whereas a relative lack of cell-mediated immunity and involvement of humoral immunity may be present in schizophrenia. These data provide a rationale for immune-based strategies of study and therapeutics in childhood neuropsychiatric disease.