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1.
Methoxybromo derivatives of unsaturated fatty acids including conjugated acids yield simple mass spectra and can be used to
locate the position of double bonds in these acids. The derivatives are prepared under mild conditions by bromination of the
unsaturated fatty acids in methanol. The method is illustrated with the methoxybromo derivatives from methyl esters of oleic,
petroselenic, erucic, undecenoic, linoleic, linolenic, the conjugated diene acids from dehydrated castor oil, α-eleostearic,
punicic and parinaric acids. Unlike other methods using methoxy derivatives, the methoxybromo derivatives yield fewer ions,
the diagnostic peaks forming the most intense ions of the spectra. While unambiguous double bond location is possible with
monoenoic acids and conjugated fatty acids, only the end carbon atoms of the unsaturation system in nonconjugated polyenoic
acids is located. But the characteristic appearance of fragments corresponding to [CH3(CH2)nCH(OMe)CH(Br)CH2−2H]+ and fragments 24 mass units higher than those which locate the end carbons in such fatty acids indicate a methylene-interrupted
system of double bonds. 相似文献
2.
Multiplicative speckle noise diminishes the radiometric resolution of the synthetic aperture radar (SAR) images and all the coherent images. Speckle removal adds an extra value to an automated SAR image interpretation and analysis. In this paper, dual-tree complex wavelet-transform-based Bayesian method is proposed for despeckling the SAR images. In each subband, the reflectance and noise of the logarithmically transformed wavelet coefficients are modeled using heavy-tailed Burr and zero-mean Gaussian distributions. The closed-form expression for the shape parameter of Burr distribution is derived by employing the Mellin transform. The resultant complex-free quadratic maximum a posteriori solution with suitable shrinkage function yields despeckled SAR images. Extensive experiments are carried out using real SAR images as well as simulated images. The proposed method performs well in terms of equivalent number of looks with 3.5751 dB improvement in homogeneous region1 of Pipe river SAR image, edge preservation with 0.6158 improvement, peak signal to noise ratio of 51.3305 dB, and mean structural similarity index measure of 0.9397 at 0.05 noise variance for synthetically speckled image in comparison to the existing methods and takes averagely 2.3461 times less computing time. The proposed method provides a computationally efficient better speckle reduction in homogeneous regions while still preserving the edge. 相似文献
3.
Anne Stöbener Mario Fabuel Ortega Christoph J. Bolten Edwin Ananta Shantha Nalur Andreas Liese 《International Journal of Food Science & Technology》2020,55(3):1265-1271
Partial glycerides are widely used ingredients in confectionery products that can be produced from natural fats. In a biocatalytic partial hydrolysis of cocoa butter and palm oil fractions, a product mixture containing 1.5% monoglycerides and 5.5% diglycerides intended for the use in confectionery products was created. This study is a proof of principle that shows the feasibility of monitoring the biocatalytic partial hydrolysis of these two natural fats in situ with ATR-FTIR spectroscopy. An economic approach was utilised for calibration since partial glyceride calibration standards are costly and poorly available. The released compounds were quantified by means of chemometric modelling, and the model was validated with gas chromatography. Resulting root mean square errors were in the low per cent range. Additionally, the results indicate that distinction of the released free fatty acids is possible with ATR-FTIR spectroscopy. 相似文献
4.
Selva Nidhyanandhan S. Sindhuja R. Selva Kumari R. Shantha 《Wireless Personal Communications》2020,114(4):2909-2921
Wireless Personal Communications - Major issue in marine environment imaging is the expulsion of hazy scenes caused by natural phenomena such as absorption and scattering in underwater images. The... 相似文献
5.
Accelerated weathering properties of compatibilized composites made from recycled HDPE and nonmetallic printed circuit board waste 下载免费PDF全文
The main aim of this work is to examine the influence of the contents of nonmetallic printed circuit board (PCB) waste component on the photodegradation of recycled high‐density polyethylene (rHDPE) composites. The properties tested were chemical changes, flexural properties, color stability, water absorption, leaching properties, and crystallinity changes of the composites after exposure to 2,000 h of accelerated weathering. Surface degradation for composites with nonmetallic PCB was less compared to unfilled rHDPE mainly because glass fibers covered almost the whole surface of specimens, acting as a protective layer, thus, slowing down the photodegradation reaction. Incorporation of compatibilizer in rHDPE/PCB composites had played an important role in resisting degradation due to UV exposure. All the composite samples became lighter in the early stages of weathering exposure; however, compatibilized composites showed less lightening and reduction on strength and modulus. Carbonyl index increases with exposure time indicating that the oxidation reaction continuously occurred during the aging process. Incorporation of compatibilizer had successfully reduced the water absorption uptake by the composites and effectively delayed some degradation properties of weathering. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43110. 相似文献
6.
R. Vidya Sagar B.K. Raghu Prasad S. Shantha Kumar 《Cement and Concrete Research》2012,42(8):1094-1104
Notched three point bend (TPB) specimens made with plain concrete and cement mortar were tested under crack mouth opening displacement (CMOD) control at a rate of 0.0004 mm/s and simultaneously acoustic emissions (AE) released were recorded during the experiments. Amplitude distribution analysis of AE released during concrete was carried out to study the development of fracture process in concrete and mortar specimens. The slope of the log-linear frequency–amplitude distribution of AE is known as the AE based b-value. The AE based b-value was computed in terms of physical process of time varying applied load using cumulative frequency distribution (Gutenberg–Richter relationship) and discrete frequency distribution (Aki's method) of AE released during concrete fracture. AE characteristics of plain concrete and cement mortar were studied and discussed and it was observed that the AE based b-value analysis serves as a tool to identify the damage in concrete structural members. 相似文献
7.
Thimmappaiah N. Bhavanishankar Thimmappaji Shantha 《Journal of the science of food and agriculture》1987,40(4):327-332
Peanut, sorghum and maize samples were collected from the wholesale market in Mysore, India, over a period of one year (October 1984 to September 1985). The samples were analysed for the natural occurrence of T-2 toxin (T-2), diacetoxyscirpenol (DAS) and zearalenone by thin-layer chromatography, dermal toxicity test and gas chromatography. Of the total number of peanut samples analysed, 6.9% were positive for the toxic trichothecene(s) (T-2, up to 38.89 mg kg?1; DAS, up to 2.03 mg kg?1); 4.8% of total sorghum samples analysed contained T-2 up to 15 mg kg?1. Zearalenone was not found in any of the samples tested, and no toxins were detected in any of the maize samples. Samples marketed during winter and summer periods were contaminated with the toxins. All the toxin-positive samples except one peanut sample were found in produce stored for more than a week. 相似文献
8.
Kosaraju SL 《Critical reviews in food science and nutrition》2005,45(4):251-258
Colon-targeted delivery of bioactives has recently gained importance in addressing specific needs in the therapy of colon-based diseases. Many approaches have been attempted for the development of colon-specific delivery systems, with not much success in the past. Recent research into the utilization of the metabolic activity and the colonic microenvironment in the lower gastrointestinal tract has attained great value in the design of novel colon-targeted delivery systems based on natural biodegradable polymers. In the current article, special emphasis has been placed on polysaccharide systems, with minimal chemical modification, that have been exploitedfor colon targeting. These polysaccharide based encapsulation and targeted delivery systems are envisaged to have an immense potential for the development of food/nutraceutical formulations for colon-based diseases, including colorectal cancer. 相似文献
9.
Wireless Personal Communications - Researchers concentrate on big data. Wireless sensor network is one of the sources of big data. Wireless sensor network has hundreds of sensor nodes with limited... 相似文献
10.
S. Selva Nidhyananthan R. Shantha Selva kumari V. Shenbagalakshmi 《International Journal of Speech Technology》2016,19(3):577-583
In this paper, the role of speech recognition system in the assessment of dysarthric speech based on a method called Elman back propagation network (EBN) is studied. Dysarthria is a neurological disability that damages the control of motor speech articulators. The persons who suffer from Dysarthria may have speech intelligibility rate which may vary from low (2 %) to high (95 %). EBN is a Recurrent network, here a fully connected neural network is built such that the speech characteristics are represented simultaneously by neuron activation states. It is an efficient self supervised training algorithm. For parametric representation of the speech signal, we used Glottal feature along with mel frequency cepstral coefficients. Then finally the output of both the features is compared after the evaluation process using different neural networks and modeling methods. Evaluation of the proposed method is done on the subset of the Universal Access Research database. The subset consists of 9 dysarthric speakers out of 19 speakers each uttering 100 words repeatedly 3 times. The promising performance of the proposed system can be successfully applied to help the people who work for the voice disorder persons. 相似文献