1,648 research outputs found
Effect of dietary conjugated linoleic acid (CLA) on carcass quality, serum lipid variables and histopathological changes of broiler chickens infected with aflatoxin B1
Three dietary inclusion rates of CLA (0, 2 and 4 g/kg feed) and aflatoxin B1 (0, 200 and 300 μg/kg feed) were tested in a 3 x 3 factorial experimental design on a total of 99 Ross-308 male broiler chickens from 1 to 42 days of age. The objective of this study was to determine the effect of dietary conjugated linoleic acid (CLA) on carcass characteristics, serum lipid variables and histopathological properties in broiler chickens receiving a diet containing aflatoxin B1 (AFB1). Carcass yield, abdominal fat weight and abdominal fat percentage were not significantly influenced by dietary CLA, AFB1 or CLA + AFB1. Altered serum lipid measurements induced by AFB1 treatments included increased serum cholesterol and triglyceride concentrations, and decreased serum concentration of high density lipoprotein (HDL). Serum HDL concentration was increased in birds supplemented with 2 and 4 g CLA/kg diet compared with the control group. However, CLA + AFB1 did not significantly affect these parameters compared to the groups that received AFB1 alone. Aflatoxin B1 administration induced degenerative changes in the liver tissue, but dietary CLA supplementation offered protection to the livers against these changes. Aflatoxin B1 residues were not detected in any breast tissues collected from the broiler carcasses. Our results suggest that CLA provided protection against the negative effects of liver damage induced by AFB1 in broiler chickens. Furthermore, dietary CLA supplementation increased serum HDL levels. Keywords: Aflatoxin B1; conjugated linoleic acid;carcass quality; hepatotoxicity; serum lipid variables South African Journal of Animal Sciences Vol. 35 (2) 2005: pp.109-11
Supersymmetric approach to exactly solvable systems with position-dependent effective masses
We discuss the relationship between exact solvability of the Schr\"{o}dinger
equation with a position-dependent mass and the ordering ambiguity in the
Hamiltonian operator within the frame of supersymmetric quantum mechanics. The
one-dimensional Schr\"{o}dinger equation, derived from the general form of the
effective mass Hamiltonian, is solved exactly for a system with exponentially
changing mass in the presence of a potential with similar behaviour, and the
corresponding supersymmetric partner Hamiltonians are related to the
effective-mass Hamiltonians proposed in the literature.Comment: 12 pages article in LaTEX (uses standard article.sty). Please check
http://www1.gantep.edu.tr/~ozer for other studies of Nuclear Physics Group at
University of Gaziantep. [arXiv admin note: excessive overlap with
quant-ph/0306065 and "Supersymmetric approach to quantum systems with
position-dependent effective mass" by A. R. Plastino, A. Rigo, M. Casas, F.
Garcias, and A. Plastino - Phys. Rev. A 60, 4318 - 4325 (1999)
Raman Enhancement on a Broadband Meta-Surface
Cataloged from PDF version of article.Plasmonic metamaterials allow confinement of light to deep subwavelength dimensions, while allowing for the tailoring of dispersion and electromagnetic mode density to enhance specific photonic properties. Optical resonances of plasmonic molecules have been extensively investigated; however, benefits of strong coupling of dimers have been overlooked. Here, we construct a plasmonic meta-surface through coupling of diatomic plasmonic molecules which contain a heavy and light meta-atom. Presence and coupling of two distinct types of localized modes in the plasmonic molecule allow formation and engineering of a rich band structure in a seemingly simple and common geometry, resulting in a broadband and quasi-omni-directional meta-surface. Surface-enhanced Raman scattering benefits from the simultaneous presence of plasmonic resonances at the excitation and scattering frequencies, and by proper design of the band structure to satisfy this condition, highly repeatable and spatially uniform Raman enhancement is demonstrated. On the basis of calculations of the field enhancement distribution within a unit cell, spatial uniformity of the enhancement at the nanoscale is discussed. Raman scattering constitutes an example of nonlinear optical processes, where the wavelength conversion during scattering may be viewed as a photonic transition between the bands of the meta-material
The Road to 6G: Ten Physical Layer Challenges for Communications Engineers
While the deployment of 5G cellular systems will continue well in to the next
decade, much interest is already being generated towards technologies that will
underlie its successor, 6G. Undeniably, 5G will have transformative impact on
the way we live and communicate, yet, it is still far away from supporting the
Internet-of-Everything (IoE), where upwards of a million devices per
(both terrestrial and aerial) will require ubiquitous,
reliable, low-latency connectivity. This article looks at some of the
fundamental problems that pertain to key physical layer enablers for 6G. This
includes highlighting challenges related to intelligent reflecting surfaces,
cell-free massive MIMO and THz communications. Our analysis covers theoretical
modeling challenges, hardware implementation issues and scalability among
others. The article concludes by delineating the critical role of signal
processing in the new era for wireless communications.Comment: IEEE Communications Magazine, Accepte
Схемотехническое моделирование и синтез активных СВЧ-фильтров на полевых транзисторах Шоттки
Разработаны схемы активных СВЧ-фильтров, пригодных для исполнения в виде гибридной или полупроводниковой микросхемы
Sludge reduction with pulse ozonation
Biyolojik atıksu arıtma tesislerinde atıksuyun arıtılmasının yanı sıra fazla çamurun da uzaklaştırılması önemlidir. Tesis işletme maliyetlerinin yaklaşık yarıdan fazlası çamur bertarafına harcanmaktadır. Bu nedenle uygulanabilir, ekonomik ve yenilikçi yöntemler araştırılmaktadır. Araştırılan süreçler arasında ozon güçlü bir oksidan olarak ön plana çıkmaktadır. Bu çalışmada 15-30 gün gibi uzun süren aerobik çürütmeyi kısaltmak için havalandırmaya ilave olarak ozon kullanılması araştırılmıştır. Benzer çalışmalardan farklı olarak araştırmada ozon sürekli olarak kullanılmamış olup bakterilerin ikileme zamanı dikkate alınarak 24 saatte bir kez pals şeklinde kısa sürelerle tatbik edilmiştir. Böylece ozonun biyolojik parçalanmaya olan etkisi de incelenmiştir. Ankara Tatlar Atıksu Arıtma Tesisi Havalandırma Tankı’ndan alınan numuneler ile yapılan deneyler sırasında günde bir kez erlenlerdeki çamurlara 2, 3, 4 ve 6 dakikalık sürelerle ozonlama yapılmış, daha sonra çamur 24 saat süreyle çalkalayıcıda bekletilmiştir. Dört gün süreyle devam eden deneylerde rutin olarak TKM, UKM, KOİ ve OTH ölçümleri yapılmıştır. Sonuç olarak bu süre bitiminde UKM indirgenmesi 2, 3, 4 ve 6 dakika ozonlamalar için sırasıyla %22.6, %40, %75 ve %84 olarak tespit edilmiştir. Standart havasal çamur çürütme ile elde edilen çamur azaltımı %40-50 iken kesikli ozonlama ile elde edilen çamur azaltımı % 80 üzerine çıkmıştır. Yine reaksiyon süresi 20-30 günden 4 günlere inmiştir. Ozon destekli çürütülmüş çamurda yapılan koli basili analizleri de çamurdaki koli basillerinin bu süre içersinde tamamen öldürüldüğünü göstermiştir. Yine ozon destekli havasal çürütmede önemli mitarda ortama fosfor salınmadığı görülmüştür. Anahtar Kelimeler: Ozon, çamur degredasyonu, bakteri, ikileme zamanı, pals.Biological treatment is one of the most widely used treatment techniques. Although its high efficiency and easy design make it a preferable option, excess sludge production is a massive burden for the facilities. Approximately, half of the operation cost for domestic wastewater treatment plants is spent for sludge treatment and disposal. Even after treatment it may act as a secondary pollution source at the disposal site due to its heavy metal, pathogen and persistent organic pollutant contents. Therefore, several strategies are considered for excess sludge treatment. Incineration, dewatering, landfilling and use for agricultural purposes are some of them. However, since regulations on the use and disposal of excess sludge are much more stringent than past years, people tend to use methods which reduce the volume of sludge such as thermal, mechanical, chemical and oxidation pretreatment. Ozonation which is a chemical treatment method establishes disintegration by two mechanisms: first one is the destruction of the cell wall of the microorganism and the second one is the mineralization of the intracellular components. According to high degree of disintegration and cost effectiveness of ozonation make it a feasible technique among the other disintegration techniques. Consequently, ozone treatment of sludge gaining popularity and this leads to a new area of study in environmental engineering. The common point of previous studies is the continuous ozonation of the samples. However, ozone is a very expensive chemical to be wasted. Therefore it should be used properly. That led us to consider about pulse ozonation of sludge which would be economically more feasible if it can be as efficient as continuous ozonation. In this study it was planned to use ozone as a substitute to shorten the 15-30 day-long aerobic digestion process. Waste activated sludge samples from Ankara Tatlar Wastewater Treatment Plant were ozonated for 2, 3, 4 and 6 minutes respectively in Erlenmeyer flasks once a day on each of four consecutive days and left for incubation in between on a shaker. In the experiments, ozone was supplied by OSC-Modular 4HC, WEDECO ITT INDUSTRIES (2007) ozone generator. Operating pressure of the generator is 5 bar and the gas flow rate is 10-140 L/hr with a rated capacity of 4 g/hr. Ozone amount that is released to water in time interval was measured by using Standard Methods 8021 (DPD chlorine reagent) and calibration curve was obtained by spectrophoto-metric measurement (for 25 mL sample). The MLVSS, MLSS, COD and OUR parameters were measured routinely during the four days. MLSS measurements were done according to Standard Methods (2540B) (APHA, 1998). Chemical oxygen demand (COD) was measured by Hach Lange kits according to HACH 8000(US EPA approved) method. Volatile Suspended Solids (MLVSS) was measured according to 2540 solids method. Total-P was analyzed by 365.4 EPA Method and ortho-phosphate was analysed with 365.3 EPA Method. Obviously, one of the most important reasons of sludge treatment is sludge disinfection. In order to have an opinion about this concept, it was decided to count E.coli in the sludge. Also considering the possibility of phosphorus release, total phosphorus and ortho-phosphate were checked in the 6' ozonated sample. At the first day, total phosphorus of the sludge was 0.006 g per g biomass and after the first ozonation this amount increased to 0.0082. By these results, it can be concluded that ozonation does not release significant amounts of phosphorus to the medium. At the end of the experiments, MLVSS reductions for 2, 3, 4, and 6 minutes were observed as 22.6%, 40%, 75% and 84% respectively. As a result of the experiments, by the pulse ozonation of the non-digested activated sludge, both stabilization and reduction of the sludge were achieved in such short period as 4 days. Moreover, it can be ascertained that the obtained sludge was both disinfected from E.coli and phosphorus rich. Furthermore, since the COD left in the medium after the experiments was biodegradable, it was concluded that it would be feasible to return to the beginning of the system. Hence, it became possible to save on both time of contact and the amount of ozone used in comparison with other studies where samples were ozonated on continuous bases. The obtained results show similar values for MLVSS, MLSS and COD for both 4' and 6' ozonation for first 3 days. Nevertheless, since the 6' ozonation is more effective in sludge stabilization, after the 4' ozonation for the first 3 days, 6' ozonation for the 4th day is suggested. Keywords: Ozone, sludge degradation, bacteria, doubling time, pulse
Adsorption of emerging contaminants by graphene related materials and their alginate composite hydrogels
Graphene nanosheets and nanoplatelets -alginate composite hydrogels were prepared by ionic gelation and the resulting gel beads were exploited for the removal of a mixture of eight selected emerging contaminants (ECs) in tap water, including bisphenol A, ofloxacin and diclofenac. The role of graphene related materials (GRM) on the gel bead structure, adsorption selectivity, kinetic, mechanism, and efficiency was investigated. Combined Scanning Electron Microscopy (SEM) and confocal Raman microscopy mapping showed a porous structure with pore size in the range of 100–200 µm and a homogeneous distribution of graphene nanosheets or nanoplatelets at the pores surface. The adsorption kinetic of GRM was much faster than that of granular activated carbon (GAC), the industrial sorbent benchmark, with removal capacity of ofloxacin from 2.9 to 4.3 times higher. A maximum adsorption capacity of 178 mg/g for rhodamine B was estimated by adsorption isotherm studies for reduced graphene oxide-based beads (a value comparable to that of powered activated carbon). Regeneration test performed on saturated beads by washing with EtOH, and subsequent reiterated reuses, showed no loss of adsorption performance up to the fourth reuse cycle
III/V-on-lithium niobate amplifiers and lasers
We demonstrate electrically pumped, heterogeneously integrated lasers on thin-film lithium niobate, featuring electro-optic wavelength tunability. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen
- …