401 research outputs found

    Trogidae (Coleoptera : Scarabaeoidea) in forensic entomology : occurrence of known and new species in Queensland, Australia

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    During studies of necrophagous insect succession in pig carcases that were used as surrogates for human corpses, Trogidae were found to be fairly common at the carcases at a study site in south-east Queensland. During the identification of the species, one of the regular visitors to the carcases was found to be undescribed (Omorgus (Omorgus) bachorum sp. nov.). It is described in this paper. Also, while comparing the undescribed species to that of specimens in the Queensland Museum collection, another undescribed species was discovered, which is also described in this paper (Omorgus (Omorgus) undaraensis sp. nov.). One new synonym, Omorgus incognitus Strümpher & Scholtz, 2011 syn. nov., is also proposed; bringing the total number of Australian species of Omorgus Erichson, 1847 to 57.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)2052-17582015-11-30hb201

    Pemanfaatan Limbah Kulit Singkong untuk Produksi Oligosakarida melalui Hidrolisis Kimiawi

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    Cassava peels are biomass wastes that is rich of polysaccharides. Polysaccharides can be hydrolyzed  chemically under control to produce  oligosaccharides. The aims of this research are to study the suitability of the type of acids and the concentration of acids to hydrolyze, and analize the hydrolysis product using spectrophotometer and thin layer chromatography (TLC). The acids used in the hydrolysis were chloride acid, sulphuric acid, phosphoric acid, acetic acid, and citric acid, in concentration 0.3; 0.4, 0.5; 0.6; 0.7 molar. Total sugar was determined using phenol method. Analysis of reducing sugar  was performed by the DNS method. The ratio of total sugar to reducing sugar was used to predict the degree of polymerization (DP). Almost all of acids with each concentration produced DP 2-6. The results were also confirmed using TLC and the retardation factor (Rf) compared using glucose and maltose as relative standards.Keywords: cassava peel waste, oligosaccharide, chemical hydrolysi

    Studi Eksperimental dan Pemodelan Matematika Proses Pengeringan Kakao Dengan Energi Surya Secara Intermitten

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    In this research, the behaviors of cocoa drying using solar dryers have been studied. Cocoa was taken from plantation area around North Sumatra - Indonesia. Solar energy is used as a source of energy that save and clean for drying. Cocoa is a mainstay in Indonesian commodities, but quality of the current generated is relatively low. The aims of this research to gain the quality with mathematical modelling of drying by producing a good quality of cocoa. Preparation phase started from cocoa fermentation process. With some testing times, it was taken one test where the results of fermented cocoa that had been washed and dried from water content 55.83% to 7.01%, which lasted for three days, 22 to 24 April 2013 from at 7:00 to 17:00 pm (intermittent). The study was conducted at the Solar Energy Laboratory, Faculty of Engineering Department of Mechanical Engineering of North Sumatra University Medan. It is located in Medan city with the position of 3.36 ° N - 98.4 ° E, altitude 200 meters above sea level and meridian time (GMT +7). From the experimental results obtained an experimental equation mathematical model for intermittent drying of cocoa, with the value of diffusivity coefficient was between 1.39 x10-10 to 1.85 x10-10 m2/sec, besides the quality of the dried cocoa in this study was better in colour and not moldy than dried cacao directly under the sun. ABSTRAK Pada penelitian ini, perilaku pengeringan menggunakan pengering kakao tenaga surya telah dilakukan. Kakao diambil dari perkebunan di sekitar daerah Sumatera Utara – Indonesia. Energi surya digunakan sebagai sumber energi pengeringan yang hemat dan bersih. Kakao merupakan komoditi andalan di Indonesia hanya saja mutu yang saat ini dihasilkan masih terbilang rendah. Penelitian ini bertujuan mendapatkan persamaan pengeringan dengan pemodelan matematika untuk menghasilkan mutu kakao yang baik. Tahap preparasi dimulai dari proses fermentasi kakao. Dengan beberapa kali pengujian kakao, diambil hasil salah satu pengujian dimana hasil fermentasi kakao yang telah dicuci kemudian dikeringkan dari kadar air 55,83% menjadi 7,01% yang berlangsung selama tiga hari yakni 22–24 April 2013 dari pukul 07.00 – 17.00 WIB (Intermitten).  Penelitian dilakukan di Laboratorium Solar Energi Jurusan Teknik Mesin Fakultas Teknik Universitas Sumatera Utara Medan yang berada di kota Medan dengan posisi 3.36 °LU – 98.4 °BT, ketinggian di atas permukaan laut 200 meter dan waktu meridian (7 + GMT). Dari hasil percobaan percobaan didapat persamaan model matematika untuk pengeringan kakao secara intermitten, dengan nilai koefisien difusifitas berada pada nilai 1,39 x10-10 – 1,85 x10-10 m2/detik, selain itu kualitas kakao yang dikeringkan lebih baik dari segi warna dan tidak berjamur dibandingkan dengan kakao yang dikeringkan secara langsung dibawah sinar matahari

    Model for nucleation in GaAs homoepitaxy derived from first principles

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    The initial steps of MBE growth of GaAs on beta 2-reconstructed GaAs(001) are investigated by performing total energy and electronic structure calculations using density functional theory and a repeated slab model of the surface. We study the interaction and clustering of adsorbed Ga atoms and the adsorption of As_2 molecules onto Ga atom clusters adsorbed on the surface. The stable nuclei consist of bound pairs of Ga adatoms, which originate either from dimerization or from an indirect interaction mediated through the substrate reconstruction. As_2 adsorption is found to be strongly exothermic on sites with a square array of four Ga dangling bonds. Comparing two scenarios where the first As_2 gets incorporated in the incomplete surface layer, or alternatively in a new added layer, we find the first scenario to be preferable. In summary, the calculations suggest that nucleation of a new atomic layer is most likely on top of those surface regions where a partial filling of trenches in the surface has occurred before.Comment: 8 pages, 14 figures, Submitted to Phys. Rev. B (December 15, 1998). Other related publications can be found at http://www.fhi-berlin.mpg.de/th/paper.htm

    Eigenvector statistics in non-Hermitian random matrix ensembles

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    We study statistical properties of the eigenvectors of non-Hermitian random matrices, concentrating on Ginibre's complex Gaussian ensemble, in which the real and imaginary parts of each element of an N x N matrix, J, are independent random variables. Calculating ensemble averages based on the quantity <Lα∣Lβ>< L_\alpha | L_\beta > , where <Lα∣< L_\alpha | and ∣Rβ>| R_\beta > are left and right eigenvectors of J, we show for large N that eigenvectors associated with a pair of eigenvalues are highly correlated if the two eigenvalues lie close in the complex plane. We examine consequences of these correlations that are likely to be important in physical applications.Comment: 4 pages, no figure

    Optically-stimulated desorption of 'hot' excimers from pre-irradiated Ar solids

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    Electronically-induced desorption from solid Ar pre-irradiated by a low-energy electron beam was investigated by activation spectroscopy methods - photon-stimulated exoelectron emission and photon-stimulated luminescence in combination with spectrally-resolved measurements in the VUV range of the spectrum. Desorption of vibrationally excited argon molecules Ar2^*(v) from the surface of pre-irradiated solid Ar was observed for the first time. It was shown that desorption of 'hot' Ar2^*(v) molecules is caused by recombination of self-trapped holes with electrons released from traps by visible range photons. The possibility of optical stimulation of the phenomenon is evidenced.Comment: The complete version of the paper will be published in Fiz. Nizk. Temp. (Low Temp. Phys.

    Expression Profiles of 2 Phosphate Starvation-Inducible Phosphocholine/Phosphoethanolamine Phosphatases, PECP1 and PS2, in Arabidopsis

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    Phosphorus is essential for plant viability. Phosphate-starved plants trigger membrane lipid remodeling to replace membrane phospholipids by non-phosphorus galactolipids presumably to acquire scarce phosphate source. Phosphoethanolamine/phosphocholine phosphatase 1 (PECP1) and phosphate starvation-induced gene 2 (PS2) belong to an emerging class of phosphatase induced by phosphate starvation and dephosphorylates phosphocholine and phosphoethanolamine (PEtn) in vivo. However, detailed spatiotemporal expression pattern as well as subcellular localization has not been investigated yet. Here, by constructing transgenic plants harboring functional translational promoter–reporter fusion system, we showed the expression pattern of PECP1 and PS2 in different tissues and in response to phosphate starvation. Besides, the Venus fluorescent reporter revealed that both are localized at the ER. Characterization of transgenic plants that overexpress PECP1 or PS2 showed that their activity toward PEtn may be different in vivo. We suggest that PECP1 and PS2 are ER-localized phosphatases that show similar expression pattern yet have a distinct substrate specificity in vivo

    Differences in genotype and virulence among four multidrug-resistant <i>Streptococcus pneumoniae</i> isolates belonging to the PMEN1 clone

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    We report on the comparative genomics and characterization of the virulence phenotypes of four &lt;i&gt;S. pneumoniae&lt;/i&gt; strains that belong to the multidrug resistant clone PMEN1 (Spain&lt;sup&gt;23F&lt;/sup&gt; ST81). Strains SV35-T23 and SV36-T3 were recovered in 1996 from the nasopharynx of patients at an AIDS hospice in New York. Strain SV36-T3 expressed capsule type 3 which is unusual for this clone and represents the product of an in vivo capsular switch event. A third PMEN1 isolate - PN4595-T23 - was recovered in 1996 from the nasopharynx of a child attending day care in Portugal, and a fourth strain - ATCC700669 - was originally isolated from a patient with pneumococcal disease in Spain in 1984. We compared the genomes among four PMEN1 strains and 47 previously sequenced pneumococcal isolates for gene possession differences and allelic variations within core genes. In contrast to the 47 strains - representing a variety of clonal types - the four PMEN1 strains grouped closely together, demonstrating high genomic conservation within this lineage relative to the rest of the species. In the four PMEN1 strains allelic and gene possession differences were clustered into 18 genomic regions including the capsule, the blp bacteriocins, erythromycin resistance, the MM1-2008 prophage and multiple cell wall anchored proteins. In spite of their genomic similarity, the high resolution chinchilla model was able to detect variations in virulence properties of the PMEN1 strains highlighting how small genic or allelic variation can lead to significant changes in pathogenicity and making this set of strains ideal for the identification of novel virulence determinant
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