Liquid hydridosilane precursor prepared from cyclopentasilane via sonication at low temperatures without the action of light.

We report on a liquid hydridosilane precursor ink prepared via the ultrasonically induced ring-opening polymerisation of cyclopentasilane (Si5H10) without irradiation by ultraviolet light. The sonication is carried out in N2 atmosphere at temperatures between 20 and 75°C. We use size exclusion chromatography (SEC) to show polymer growth and estimate molecular mass with increasing sonication time. In combination with UV-vis transmission measurements, further SEC analysis is used to compare solutions subjected to either purely thermal or ultrasonic treatment at the same process temperature and for the same duration. Our findings provide strong evidence showing that the initiation of the polymerisation is sonocatalytic in nature and not thermic due to the macroscopic temperature of the solution. The liquid precursor is used to produce homogeneous hydrogenated amorphous silicon (a-Si:H) thin films via spin coating and pyrolytic conversion. The optoelectronic properties of the films are subsequently improved by hydrogen radical treatment. Fourier transform infrared spectroscopy (FTIR) is used to determine a compact film morphology and electrical conductivity measurements show that the layers attain a light-to-dark photosensitivity ratio of 2×103 making them suitable for application in optoelectronic devices.

Effect of hydrocooling, packaging, and cold storage on the post-harvest quality of peppermint (Mentha piperita L. ) / Efeito do hidroresfriamento e embalagem sobre hortelã-pimenta fresca armazenada em temperatura ambiente e ambiente refrigerado

ABSTRACT The purpose of this study was to assess the effects of hydrocooling and polyethylene terephthalate (PET) perforated and non-perforated packaging on post-harvest quality of peppermint (Mentha piperita L.) leaves stored at 5 and 25ºC. The experiments were conducted using a subdivided parcel layout in a completely randomized design with four replicates. Each parcel used a 2x3 layout (two hydrocooling treatments and three packaging treatments) with subparcels for storage time. The shelf life, chlorophyll content, mass loss (ML), relative water content (RWC), total soluble sugars (TSS), reducing sugars (Red), non-reducing sugars (NRed) and starch of the leaves were determined. Cold storage increased the shelf life of the peppermint by up to 64 times (>15 days). Hydrocooling increased the RWC of the leaves. Plastic packaging was effective in maintaining the RWC. Unperforated packages more effectively prevented ML in the peppermint leaves and prevented the leaves from wilting for a longer period of time. The chlorophyll content of the leaves varied according to the treatment. The soluble sugars and starch levels varied according to RWC. Hydrocooling with the use of non-perforated plastic packages was the most effective method for maintaining the postharvest quality of the peppermint.

RESUMO O trabalho objetivou avaliar os efeitos do hidroresfriamento e da embalagem de politereftalato de etileno (PET) perfurada e não perfurada na qualidade pós-colheita de folhas de hortelã pimenta (Mentha piperita L.) armazenadas em temperatura ambiente e sob refrigeração. Os experimentos foram instalados seguindo o esquema de parcela subdividida, tendo na parcela o esquema fatorial 2x2 (dois tratamentos envolvendo hidroresfriamento e dois tratamentos envolvendo embalagens) e nas subparcelas os tempos de armazenamento no delineamento inteiramente casualizado com quatro repetições. Foi determinada a vida de prateleira, os teores de clorofila, a perda de massa fresca (PM), o teor relativo de água (TRA), os teores de açúcares solúveis totais (AST), redutores (RED), não redutores (NRED) e amido das folhas. O armazenamento refrigerado aumentou em até 64 vezes (>15 dias) a vida de prateleira de hortelã-pimenta. O hidroresfriamento aumentou o TRA das folhas. A embalagem plástica foi efetiva no aumento da vida de prateleira de hortelã-pimenta sendo eficiente na manutenção dos TRA das folhas. A embalagem não perfurada foi mais eficiente na prevenção da PM. O teor de clorofila das folhas variou de acordo com o tratamento. AST, RED, NRED e amido variaram de acordo com TRA nas folhas. O hidroresfriamento juntamente com utilização de embalagem não perfurada foi o método mais eficiente na manutenção da qualidade pós-colheita de hortelã-pimenta.

Epistasis and inheritance of plant habit and fruit quality traits in ornamental pepper (Capsicum annuum L.).

Two accessions of ornamental pepper Capsicum annuum L., differing in most of the characters studied, were crossed, resulting in the F1 generation, and the F2 generation was obtained through self-fertilization of the F1 generation. The backcross generations RC1 and RC2 were obtained through crossing between F1 and the parents P1 and P2, respectively. Morpho-agronomic characterization was performed based on the 19 quantitative descriptors of Capsicum. The data obtained were subjected to generation analysis, in which the means and additive variance (σa(2)), variance due to dominance deviation (σd(2)), phenotypic variance (σf(2)), genetic variance (σg(2)) and environmental variance (σm(2)) were calculated. For the full model, we estimated the mean effects of all possible homozygotes, additives, dominants, and epistatics: additive-additive, additive-dominant, and dominant-dominant. For the additive-dominant model, we estimated the additive effects, dominant effects and mean effects of possible homozygotes. The character fruit dry matter had the lowest value for broad sense heritability (0.42), and the highest values were found for fresh matter and fruit weight, 0.91 and 0.92, respectively. The lowest value for narrow sense heritability was for the minor fruit diameter character (0.33), and the highest values were found for seed yield per fruit and fresh matter, 0.87 and 0.84, respectively. The additive-dominant model explained only the variation found in plant height, canopy width, stem length, corolla diameter, leaf width, and pedicel length, but in the other characters, the epistatic effects showed significant values.

Combining ability for yield and fruit quality in the pepper Capsicum annuum.

The objective of this study was to determine the effects of the general and specific combining abilities (GCA and SCA, respectively) of 15 characteristics and to evaluate the most promising crosses and the reciprocal effect between the hybrids of six parents of the Capsicum annuum species. Six parents, belonging to the Horticultural Germplasm Bank of Centro de Ciências Agrárias of Universidade Federal da Paraíba, were crossed in complete diallel manner. The 30 hybrids generated and the parents were then analyzed in a completely randomized design with three replicates. The data were submitted to analysis of variance at 1% probability, and the means were grouped by the Scott-Knott test at 1% probability. The diallel analysis was performed according to the Griffing method, model I and fixed model. Both additive and non-additive effects influenced the hybrids' performance, as indicated by the GCA/SCA ratio. The non-additive effects, epistasis and/or dominance, played a more important role than the additive effects in pedicel length, pericarp thickness, fresh matter, dry matter content, seed yield per fruit, fruit yield per plant, days to fructification, and total soluble solids. The GCA effects were more important than the SCA effects in the fruit weight, fruit length and diameter, placenta length, yield, vitamin C, and titratable acidity characteristics. The results found here clearly show that ornamental pepper varieties can be developed through hybridization in breeding programs with C. annuum.

Silicon based tandem cells: novel photocathodes for hydrogen production.

A photovoltaic tandem cell made of amorphous silicon (a-Si) and microcrystalline silicon (µc-Si) was investigated as a photocathode for hydrogen evolution in a photoelectrochemical device. The electronic and electrochemical properties of the samples were characterized using X-ray photoemission spectroscopy (XPS) and cyclic voltammetry (CV), whereas the morphology of the surface in contact with the electrolyte was investigated by scanning electron microscopy (SEM). The electric efficiency of the tandem cell was determined to be 5.2% in a photoelectrochemical (PEC) setup in acidic solution which is only about half of the photovoltaic efficiency of the tandem cell. A significant improvement in efficiency was achieved with platinum as a catalyst which was deposited by physical vapour deposition (PVD) under ultra-high vacuum (UHV) conditions.

Metastable defect formation at microvoids identified as a source of light-induced degradation in a-Si:H.

Light-induced degradation of hydrogenated amorphous silicon (a-Si:H), known as the Staebler-Wronski effect, has been studied by time-domain pulsed electron-paramagnetic resonance. Electron-spin echo relaxation measurements in the annealed and light-soaked state revealed two types of defects (termed type I and II), which can be discerned by their electron-spin echo relaxation. Type I exhibits a monoexponential decay related to indirect flip-flop processes between dipolar coupled electron spins in defect clusters, while the phase relaxation of type II is dominated by 1H nuclear spin dynamics and is indicative for isolated spins. We propose that defects are either located at internal surfaces of microvoids (type I) or are isolated and uniformly distributed in the bulk (type II). The concentration of both defect type I and II is significantly higher in the light-soaked state compared to the annealed state. Our results indicate that in addition to isolated defects, defects on internal surfaces of microvoids play a role in light-induced degradation of device-quality a-Si:H.

The relationship between hydrogen and paramagnetic defects in thin film silicon irradiated with 2 MeV electrons.

After irradiation of hydrogenated amorphous and microcrystalline silicon (a-Si:H and µc-Si:H) with 2 MeV electrons at 100 K, we observe satellite-like components close to the dominating electron spin resonance (ESR) signal of these materials. The satellites overlap with the commonly observed dangling bond resonance and are proposed to originate from a hyperfine interaction with the nuclear magnetic moment of hydrogen atoms in a-Si:H and µc-Si:H. Our present study is focused on the verification of this hypothesis. Equivalent hydrogenated and deuterated a-/µc-Si:H/D materials have been investigated with ESR before and after 2 MeV electron bombardment. From the difference between ESR spectra of hydrogenated and deuterated samples we identify the doublet structure in the ESR spectra as a hyperfine pattern of hydrogen-related paramagnetic centers. The observations of H-related paramagnetic centers in a-/µc-Si:H are of particular interest in view of metastability models of a-Si:H, which include H-related complexes as precursors for the stabilization of the metastable Si dangling bonds. The nature of the observed center is discussed in the light of known H-related complexes in crystalline Si and suggested H-related dangling bonds in a-Si:H.

Genetic diversity of Capsicum chinensis (Solanaceae) accessions based on molecular markers and morphological and agronomic traits.

We estimated the genetic diversity of 49 accessions of the hot pepper species Capsicum chinensis through analyses of 12 physicochemical traits of the fruit, eight multi-categorical variables, and with 32 RAPD primers. Data from the physicochemical traits were submitted to analysis of variance to estimate the genetic parameters, and their means were clustered by the Scott-Knott test. The matrices from the individual and combined distance were estimated by multivariate analyses before applying Tocher's optimization method. All physicochemical traits were examined for genetic variability by analysis of variance. The responses of these traits showed more contribution from genetic than from environmental factors, except the percentage of dry biomass, content of soluble solids and vitamin C level. Total capsaicin had the greatest genetic divergence. Nine clusters were formed from the quantitative data based on the generalized distance of Mahalanobis, using Tocher's method; four were formed from the multi-categorical data using the Cole-Rodgers coefficient, and eight were formed from the molecular data using the Nei and Li coefficient. The accessions were distributed into 14 groups using Tocher's method, and no significant correlation between pungency and origin was detected. Uni- and multivariate analyses permitted the identification of marked genetic diversity and fruit attributes capable of being improved through breeding programs.

Genetic control of agronomically important traits of pepper fruits analyzed by Hayman's partial diallel cross scheme.

Pepper species of the genus Capsicum have been cultivated over centuries, producing both pungent and sweet fruit; the pungency is caused by alkaloids called capsaicinoids. Among the five cultivated species, Capsicum chinense is one of the most popular, being native to the Amazon basin. This species is characterized by a wide variety of fruit sizes, shapes and colors, with different capsaicinoid content. In addition, fruits are rich in vitamins A and C. Despite the importance of this plant as a spice and its medicinal uses, research on its genetic variability and potential for breeding programs is still incipient. We investigated the genetic control of some traits through diallel analysis with the objective of introgressing these traits into cultivated varieties. For the diallel analysis, the progeny of crosses between peppers with pungent and sweet fruits, together with the parents, were grown in pots under greenhouse conditions. The fruits were harvested and analyzed for the traits total fresh fruit mass, total dry fruit mass, percentage dry matter, total soluble solids, vitamin C content, fruit pungency, and number of seeds per fruit. Genetic variability was detected for all traits. In the diallel analysis, the additive-dominant model was considered to be adequate for total fresh fruit mass, percentage dry matter, total soluble solids, and vitamin C content. Additive genetic effects and dominance were found for all traits; consequently, breeding for improvement of these fruit traits would be viable.

Immunolocalization of matrix proteins in different human cartilage subtypes.

Cartilage exerts many functions in different tissues and parts of the body. Specific requirements presumably also account for a specific biochemical composition. In this study, we investigated the presence and distribution pattern of matrix components, in particular collagen types in the major human cartilages (hyaline, fibrous, and elastic cartilage) by histochemical and immunohistochemical means. Macroscopically normal articular cartilages, menisci, disci (lumbar spine), epiglottal, and tracheal tissues were obtained from donors at autopsy. Aurical and nasal cartilages were part of routine biopsy samples from tumor resection specimens. Conventional histology and immunohistochemical stainings with collagen types I, II, III, IV, V, VI, and X and S-100 protein antibodies were performed on paraformaldehyde-fixed and paraffin-embedded specimens. The extracellular matrix is the functional component of all cartilages as indicated by the low cell densities. In particular major scaffold forming collagen types I (in fibrous cartilage) and II (in hyaline and elastic cartilages) as well as collagen type X (in the calcified layer of articular cartilages, the inner part of tracheal clips, and epiglottis cartilage) showed a specific distribution. In contrast, the "minor" collagen types III, V, and VI were found in all, collagen type IV in none of the cartilage subtypes. In this study, we present a biochemical profile of the major cartilage types of the human body which is important for understanding the physiology and the pathophysiology of cartilages.

Phenotypic characterization of chondrosarcoma-derived cell lines.

Gene expression profiling of three chondrosarcoma derived cell lines (AD, SM, 105KC) showed an increased proliferative activity and a reduced expression of chondrocytic-typical matrix products compared to primary chondrocytes. The incapability to maintain an adequate matrix synthesis as well as a notable proliferative activity at the same time is comparable to neoplastic chondrosarcoma cells in vivo which cease largely cartilage matrix formation as soon as their proliferative activity increases. Thus, the investigated cell lines are of limited value as substitute of primary chondrocytes but might have a much higher potential to investigate the behavior of neoplastic chondrocytes, i.e. chondrosarcoma biology.

Comparative analysis of imbalances in genomic DNA and mRNA expression levels in chondrosarcoma-derived cell line FSCP-1.

Malignant cell transformation results from multiple biological alterations including chromosomal abnormalities, oncogene activation, loss of suppressor gene function and a imbalance in cell regulating processes. The aim of our study was to combine gene expression and genomic analysis to evaluate the cellular phenotype of a chondrosarcoma cell line, which is potentially a useful in vitro model system for physiological and/or neoplastic chondrocytes. cDNA-array, quantitative PCR and comparative genomic hybridization (CGH) technologies were used to analyze gene expression profiles of chondrosarcoma cell line FSCP-1 in correlation to changes of DNA copy number on corresponding chromosomal sections. Gene expression analysis revealed similarities, but also great differences in between the chondrosarcoma cell line and physiological chondrocytes. In particular the proliferative activity was up-regulated and molecules involved in matrix synthesis and turnover down-regulated. CGH analysis revealed a heterogeneous pattern of DNA gains or losses. The c-myc oncogene, located on 8q24.12-q24.13, was the only gene with a marked up-regulation located on a chromosome section with a gain of DNA copy number. The inability of the chondrosarcoma cell line FSCP-1 to maintain an adequate matrix turnover as well as a notable proliferative activity is similar to neoplastic chondrosarcoma in vivo. The limited correlation between the CGH analysis and the gene expression pattern supports the notion that also in neoplastic cells most genes are not primarily regulated by the gene dosage, but by cellular regulation pathways. However, genes such as c-myc might represent significant exceptions potentially relevant for the clinico-biological behavior of the neoplasms.

[cDNA-microarrays in cartilage research - functional genomics of osteoarthritis]. / cDNA-Microarrays in der Knorpelforschung - Funktionale Genomik der Osteoarthrose.

Functional genomics represents a new challenging approach in order to analyze complex diseases such as osteoarthritis on a molecular level. The characterization of the molecular changes of the cartilage cells, the chondrocytes, enables a better understanding of the pathomechanisms of the disease. In particular, the identification and characterization of new target molecules for therapeutic intervention is of interest. Also, potential molecular markers for diagnosis and monitoring of osteoarthritis contribute to a more appropriate patient management. The DNA-microarray technology complements (but does not replace) biochemical and biological research in new disease-relevant genes. Large-scale functional genomics will identify molecular networks such as yet identified players in the anabolic-catabolic balance of articular cartilage as well as disease-relevant intracellular signaling cascades so far rather unknown in articular chondrocytes. However, at the moment it is also important to recognize the limitations of the microarray technology in order to avoid over-interpretation of the results. This might lead to misleading results and prevent to a significant extent a proper use of the potential of this technology in the field of osteoarthritis.

Molecular phenotyping of human chondrocyte cell lines T/C-28a2, T/C-28a4, and C-28/I2.

OBJECTIVE: Because the immortalized chondrocyte cell lines C-28/I2, T/C-28a2, and T/C-28a4 have become a common tool in cartilage research, permitting investigations in a largely unlimited and standardized manner, we investigated the molecular phenotype of these cell lines by gene expression profiling. METHODS: Complementary DNA-array analysis as well as online quantitative polymerase chain reaction were used to identify the gene expression profiles of the 3 cell lines cultured in monolayer and alginate beads, as compared with the expression profiles of cultured human adult primary chondrocytes. RESULTS: A similar, but not identical, gene expression profile was established for all 3 cell lines. SOX9 was expressed at a significant level in all 3 cell lines. Extracellular matrix proteins and matrix-degrading proteases were rarely expressed. In contrast, genes involved in the cell cycle were strongly up-regulated, as compared with the expression levels in physiologic chondrocytes. CONCLUSION: The expression of SOX9, the master gene of chondrocytic cell differentiation, reflects the basically chondrocytic phenotype of these cells. However, the major issue appears to be that these cell lines mainly proliferate and show less expression of genes involved in matrix synthesis and turnover. In this respect, C-28/I2 cells display the highest levels of matrix-anabolic and matrix-catabolic genes and thus are presumably preferable for use in investigating chondrocyte anabolic and catabolic activity and its regulation. None of the 3 cell lines appears to be a direct substitute for primary chondrocytes. A successful approach will have to validate the findings obtained with chondrocyte cell lines by using primary chondrocytes or cartilage-tissue cultures. This would permit the establishment of reproducible in vitro models and subsequently allow investigators to relate the findings to the physiologic situation.

Synthetic interactions of the post-Golgi sec mutations of Saccharomyces cerevisiae.

In the budding yeast Saccharomyces cerevisiae, synthetic lethality has been extensively used both to characterize interactions between genes previously identified as likely to be involved in similar processes as well as to uncover new interactions. We have performed a large study of the synthetic lethal interactions of the post-Golgi sec mutations. Included in this study are the interactions of the post-Golgi sec mutations with each other, with mutations affecting earlier stages of the secretory pathway, with selected mutations affecting the actin cytoskeleton, and with selected cell division cycle (cdc) mutations affecting processes thought to be important for or involving secretion, such as polarity establishment and cytokinesis. Synthetic negative interactions of the post-Golgi sec mutations appear (as predicted) to be largely stage specific, although there are some notable exceptions. The significance of these results is discussed in the context of both secretory pathway function and the utility of synthetic lethality studies and their interpretation.

Sec3p is a spatial landmark for polarized secretion in budding yeast.

Exocytosis in yeast occurs at plasma membrane subdomains whose locations vary with the cell cycle, but the primary protein determinants of these sites are unknown. A functional fusion of Sec3 protein with green fluorescent protein (Sec3-GFP) localizes to the site of polarized exocytosis for each cell-cycle stage, where it colocalizes with Sec4p and Sec8p. Sec3-GFP localization is independent of secretory pathway function, of the actin and septin cytoskeletons, and of the polarity establishment proteins. We propose that Sec3p is a spatial landmark defining sites of exocytosis. Polarized secretion would result from the coupling of actin-dependent vesicle targeting with Sec3p-dependent establishment of the vesicle fusion site.

Characterization of Antisense Transformed Plants Deficient in the Tobacco Anionic Peroxidase.

On the basis of the biological compounds that they metabolize, plant peroxidases have long been implicated in plant growth, cell wall biogenesis, lignification, and host defenses. Transgenic tobacco (Nicotiana tabacum L.) plants that underexpress anionic peroxidase were generated using antisense RNA. The antisense RNA was found to be specific for the anionic isoenzyme and highly effective, reducing endogenous transcript levels and total peroxidase activity by as much as 1600-fold. Antisense-transformed plants appeared normal at initial observation; however, growth studies showed that plants with reduced peroxidase activity grow taller and flower sooner than control plants. In contrast, previously transformed plants overproducing anionic peroxidase were shorter and flowered later than controls. Axillary buds were more developed in antisense-transformed plants and less developed in plants overproducing this enzyme. It was found that the lignin content in leaf, stem, and root was unchanged in antisense-transformed plants, which does not support a role for anionic peroxidase in the lignification of secondary xylem vessels. However, studies of wounded tissue show some reduction in wound-induced deposition of lignin-like polymers. The data support a possible role for tobacco anionic peroxidase in host defenses but not without a reduction in growth potential.

Sec3p is involved in secretion and morphogenesis in Saccharomyces cerevisiae.

Two new temperature-sensitive alleles of SEC3, 1 of 10 late-acting SEC genes required for targeting or fusion of post-Golgi secretory vesicles to the plasma membrane in Saccharomyces cerevisiae, were isolated in a screen for temperature-sensitive secretory mutants that are synthetically lethal with sec4-8. The new sec3 alleles affect early as well as late stages of secretion. Cloning and sequencing of the SEC3 gene revealed that it is identical to profilin synthetic lethal 1 (PSL1). The SEC3 gene is not essential because cells depleted of Sec3p are viable although slow growing and temperature sensitive. All of the sec3 alleles genetically interact with a profilin mutation, pfy1-111. The SEC3 gene in high copy suppresses pfy1-111 and sec5-24 and causes synthetic growth defects with ypt1, sec8-9, sec10-2, and sec15-1. Actin structure is only perturbed in conditions of chronic loss of Sec3p function, implying that Sec3p does not directly regulate actin. All alleles of sec3 cause bud site selection defects in homozygous diploids, as do sec4-8 and sec9-4. This suggests that SEC gene products are involved in determining the bud site and is consistent with a role for Sec3p in determining the correct site of exocytosis.