59 research outputs found

    The low energy house using an air solar collector ‒ a case study

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    The main aim of this paper is to present the prospect of heating and cooling a house using solar air collectors. An analysis made of an energy-efficient house, for which the energy requirements for heating shall not exceed 40 kWh/m2/a. The calculations used air collectors with an area of 60 m2 and performance efficiency of 70%, which are available commercially. In the analyzed building the solar heating system provides almost full coverage of energy needs throughout the year, with a small shortfall occurring in December and January. The above-mentioned deficits at the beginning and end of the year can be supplemented with other alternative energy sources

    An analysis of solar energy conversion systems based on photon and thermal processes

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    Solar spectral irradiance covers a fairly broad wavelength range. Solar radiation is part of the electromagnetic spectrum which is described by the concept of wave-particle duality. The corpuscular theory of electromagnetic radiation states that energy is transmitted by photons. Photons carry specific amounts of energy which can be used to convert solar energy into other types of energy, in particular electricity.The internal photoelectric effect is important for the conversion of solar energy to electricity because the efficiency of the external photoelectric effect is too low. Every quantum of solar energy also carries a certain amount of energy which can be converted into heat energy.The objective of the paper is to analyze and compare the efficiency of solar energy conversion in photon and thermal processes, to review the technological advances made in this field, and to indicate potential directions for the development of systems converting solar energy to electricity

    Modification of emission properties of ZnO layers due to plasmonic near-field coupling to Ag nanoislands

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    A simple fabrication method of Ag nanoislands on ZnO films is presented. Continuous wave and time-resolved photoluminescence and transmission are employed to investigate modifications of visible and UV emissions of ZnO brought about by coupling to localized surface plasmons residing on Ag nanoislands. The size of the nanoislands, determining their absorption and scattering efficiencies, is found to be an important factor governing plasmonic modification of optical response of ZnO films. The presence of the Ag nanoislands of appropriate dimensions causes a strong (threefold) increase in emission intensity and up to 1.5 times faster recombination. The experimental results are successfully described by model calculations within the Mie theory.Comment: 14 pages, 5 figure

    Underexpression of LATS1 TSG in colorectal cancer is associated with promoter hypermethylation

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    AIM: To investigate large tumor suppressor 1 (LATS1) expression, promoter hypermethylation, and microsatellite instability in colorectal cancer (CRC). METHODS: RNA was isolated from tumor tissue of 142 CRC patients and 40 colon mucosal biopsies of healthy controls. After reverse transcription, quantitative polymerase chain reaction (PCR) was performed, and LATS1 expression was normalized to expression of the ACTB and RPL32 housekeeping genes. To analyze hypermethylation, genomic DNA was isolated from 44 tumor CRC biopsies, and methylation-specific PCR was performed. Microsatellite instability (MSI) status was checked with PCR using BAT26, BAT25, and BAT40 markers in the genomic DNA of 84 CRC patients, followed by denaturing gel electrophoresis. RESULTS: Decreased LATS1 expression was found in 127/142 (89.4%) CRC cases with the average ratio of the LATS1 level 10.33 ± 32.64 in CRC patients vs 32.85 ± 33.56 in healthy controls. The lowest expression was found in Dukes’ B stage tumors and G1 (well-differentiated) cells. Hypermethylation of the LATS1 promoter was present in 25/44 (57%) CRC cases analyzed. LATS1 promoter hypermethylation was strongly associated with decreased gene expression; methylated cases showed 162× lower expression of LATS1 than unmethylated cases. Although high-grade MSI (mutation in all three markers) was found in 14/84 (17%) cases and low-grade MSI (mutation in 1-2 markers) was found in 30/84 (36%) cases, we found no association with LATS1 expression. CONCLUSION: Decreased expression of LATS1 in CRC was associated with promoter hypermethylation, but not MSI status. Such reduced expression may promote progression of CRC

    Implementation of ultrasonic sensing for high resolution measurement of binary gas mixture fractions

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    We describe an ultrasonic instrument for continuous real-time analysis of the fractional mixture of a binary gas system. The instrument is particularly well suited to measurement of leaks of a high molecular weight gas into a system that is nominally composed of a single gas. Sensitivity < 5 × 10−5 is demonstrated to leaks of octaflouropropane (C3F8) coolant into nitrogen during a long duration (18 month) continuous study. The sensitivity of the described measurement system is shown to depend on the difference in molecular masses of the two gases in the mixture. The impact of temperature and pressure variances on the accuracy of the measurement is analysed. Practical considerations for the implementation and deployment of long term, in situ ultrasonic leak detection systems are also described. Although development of the described systems was motivated by the requirements of an evaporative fluorocarbon cooling system, the instrument is applicable to the detection of leaks of many other gases and to processes requiring continuous knowledge of particular binary gas mixture fractions

    Expression of estrogen receptor beta in the breast carcinoma of BRCA1 mutation carriers

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    <p>Abstract</p> <p>Background</p> <p>Breast cancers (BC) in women carrying mutations in BRCA1 gene are more frequently estrogen receptor negative than the nonhereditary BC. Nevertheless, tamoxifen has been found to have a protective effect in preventing contralateral tumors in BRCA1 mutation carriers. The identification of the second human estrogen receptor, ERβ, raised a question of its role in hereditary breast cancer. The aim of this study was to assess the frequency of ERα, ERβ, PgR (progesterone receptor) and HER-2 expression in breast cancer patients with mutated <it>BRCA1 </it>gene and in the control group.</p> <p>Methods</p> <p>The study group consisted of 48 women with <it>BRCA1 </it>gene mutations confirmed by multiplex PCR assay. The patients were tested for three most common mutations of BRCA1 affecting the Polish population (5382insC, C61G, 4153delA). Immunostaining for ERα, ERβ and PgR (progesterone receptor) was performed using monoclonal antibodies against ERα, PgR (DakoCytomation), and polyclonal antibody against ERβ (Chemicon). The EnVision detection system was applied. The study population comprised a control group of 120 BC operated successively during the years 1998–99.</p> <p>Results</p> <p>The results of our investigation showed that <it>BRCA1 </it>mutation carriers were more likely to have ERα-negative breast cancer than those in the control group. Only 14.5% of <it>BRCA1</it>-related cancers were ERα-positive compared with 57.5% in the control group (<it>P </it>< 0.0001). On the contrary, the expression of ERβ protein was observed in 42% of <it>BRCA1</it>-related tumors and in 55% of the control group. An interesting finding was that most hereditary cancers (75% of the whole group) were triple-negative: ERα(-)/PgR(-)/HER-2(-) but almost half of this group (44.4%) showed the expression of ERβ.</p> <p>Conclusion</p> <p>In the case of <it>BRCA1</it>-associated tumors the expression of ERβ was significantly higher than the expression of ERα. This may explain the effectiveness of tamoxifen in preventing contralateral breast cancer development in <it>BRCA1 </it>mutation carriers.</p
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