Influence of silver nanoparticles conditions synthesis on their electrochemical properties

The shape, size, optical properties and electrochemical activity of silver nanoparticles (AgNPs) obtained by chemical reduction methods depending on the preparation conditions were investigated. Silver solsconsist of AgNPs of different shapes. They are as follows spherical - 30 nm, polyhedral - 35 nm, 50 nm nanorods. It was shown that the position of the absorption spectrum peak in AgNPs depend on the molar ratio of mixture AgNO[3] :Na [3]C[6]H[5]O[7]. The maximum of the absorption spectrum peak of AgNPs is shifted by 10 nm to longer wavelengths area in presence excess of a reducing agent or the increasing of boiling time. After storage for one week the spectrum intensity of AgNPs obtained in the mixture AgNO[3] :Na[3]C[6]H[5]O[7]=1:1 is increased in comparison with freshly prepared AgNPs, which is caused by the increase of AgNPs quantity of a given size. The AgNPS obtained in the mixture AgNO[3] :Na[3]C[6]H[5]O[7]=1:3 have the most electrochemical activity. The conditions that the AgNPs have the most electrochemical activity were found

PENGARUH KONSENTRASI PELILINAN DAN LAMA PENYIMPANAN TERHADAP MUTU BUAH JERUK (Citrus microcarpa L.) YANG DIRENDAM DALAM LARUTAN AgNO3

Tujuan dari penelitian ini adalah untuk mengetahui pengaruh konsentrasi lilin lebah (beeswax) dan lama penyimpanan terhadap mutu buah jeruk yang tangkainya direndam dalam larutan inhibitor (AgNO 3 ). Rancangan percobaan penelitian yang digunakan adalah Rancangan Acak Kelompok (RAK) dengan pola faktorial 4 x 5 dan ulangan sebanyak 2 kali. Faktor pertama adalah konsentrasi AgNO 3 10 ppm 8 jam dan konsentrasi lilin lebah (b) terdiri dari b1 (0%), b2 (4%), b3 (8%), dan b4 (12%). Faktor kedua adalah lama penyimpanan (t) terdiri dari t1 (0 hari), t2 (4 hari), t3 (8 hari), t4 (12 hari), dan t5 (16 hari) Parameter pengamatan pada penelitian ini adalah analisis kimia meliputi kadar vitamin C, analisis fisik meliputi tingkat kekerasan dan susut bobot, serta analisis fisiko-kimia meliputi derajat keasaman (pH) dan total padatan terlarut (TPT). Hasil penelitian menunjukkan bahwa konsentrasi lilin lebah (b) berpengaruh terhadap susut bobot dan vitamin C, sedangkan lama penyimpanan (t) berpengaruh terhadap susut bobot, vitamin C, total padatan terlarut, kekerasan, dan pH. Konsentrasi lilin lebah 8% merupakan konsentrasi lilin lebah terbaik untuk parameter susut bobot, total padatan terlarut, dan pH. Sedangkan konsentrasi lilin lebah 12% merupakan konsentrasi lilin lebah terbaik untuk parameter kadar vitamin C dan tingkat kekerasan. Kata Kunci : Jeruk, AgNO 3 , dan Lilin Lebah

A Comprehensive Radio and Optical Study of Abell 2256: Activity from an Infalling Group

Abell 2256 is a nearby (z~0.06), rich cluster of galaxies with fascinating observed properties across a range of wavelengths. Long believed to represent a cluster merger, recent X-ray and optical results have suggested that in addition to the primary cluster and subcluster there is evidence for a third, poorer system. We present wide-field, high sensitivity 1.4 GHz VLA radio observations of Abell 2256 in conjunction with optical imaging and additional spectroscopy. Over 40 cluster radio galaxies are identified, with optical spectroscopy indicating the emission source (star formation or AGN) for most of them. While the overall fraction of galaxies exhibiting radio emission is consistent with a large sample of other nearby clusters, we find an increase in the activity level of galaxies belonging to the third system (hereafter, the ``Group''). Specifically, the Group has relatively more star formation than both the primary cluster and main subcluster. The position of the Group is also coincident with the observed cluster radio relic. We suggest that the Group recently (~0.3 Gyr) merged with the primary cluster and that this merger, not the ongoing merger of the primary and the main subcluster, might be responsible for many of the unusual radio properties of Abell 2256. Furthermore, the greater star formation activity of the Group suggests that the infall of groups is an important driver of galaxy evolution in clusters.Comment: 21 pages plus 13 JPEG figures; to appear in the Astronomical Journa

Abell 2255: Increased Star Formation and AGN Activity in a Cluster-Cluster Merger

Deep VLA 1.4 GHz radio continuum imaging of Abell 2255 is presented. This cluster is among the better nearby candidates for rich cluster-cluster merger systems, with evidence including an elongated X-ray morphology, the presence of a radio halo, and substructure present in its galaxy distribution. Our radio observations reach an rms sensitivity of ~40 uJy/beam, enabling us to detect (at 5 sigma) star formation rates as low as 1.4 M(sun)/year from the center of the cluster out to a radial distance of 3 Mpc. The radio data are complemented by optical imaging and a large spectroscopic database, allowing us to separate all galaxies with M_R < -20 into cluster members and foreground/background galaxies. The spectra are also used to associate the galaxies' radio emission with either star formation or AGN. We compare the resulting cluster radio galaxy population with those of nineteen other nearby Abell clusters, and find strong evidence for an increase in the frequency of radio galaxies in Abell 2255. This increase is seen in two separate types of galaxies: powerful radio AGN and optically-faint star forming galaxies. The optical spectra of the latter often indicate current or recent starbursts, and these galaxies appear to be distributed along an axis perpendicular to the probable merger axis. We assess these factors in light of models of galaxy evolution, and suggest that the cluster-cluster merger is responsible for triggering galaxy activity in Abell 2255.Comment: 21 pages, plus 13 JPEG figures; to appear in the Astronomical Journa

A family case of fertile human 45,X,psu dic(15;Y) males

We report on a familial case including four male probands from three generations with a 45,X,psu dic(15;Y)(p11.2;q12) karyotype. 45,X is usually associated with a female phenotype and only rarely with maleness, due to translocation of small Y chromosomal fragments to autosomes. These male patients are commonly infertile because of missing azoospermia factor regions from the Y long arm. In our familial case we found a pseudodicentric translocation chromosome, that contains almost the entire chromosomes 15 and Y. The translocation took place in an unknown male ancestor of our probands and has no apparent effect on fertility and phenotype of the carrier. FISH analysis demonstrated the deletion of the pseudoautosomal region 2 (PAR2) from the Y chromosome and the loss of the nucleolus organizing region (NOR) from chromosome 15. The formation of the psu dic(15;Y) chromosome is a reciprocal event to the formation of the satellited Y chromosome (Yqs). Statistically, the formation of 45,X,psu dic(15;Y) (p11.2;q12) is as likely as the formation of Yqs. Nevertheless, it has not been described yet. This can be explained by the dicentricity of this translocation chromosome that usually leads to mitotic instability and meiotic imbalances. A second event, a stable inactivation of one of the two centromeres is obligatory to enable the transmission of the translocation chromosome and thus a stably reduced chromosome number from father to every son in this family

A new data assimilation procedure to develop a debris flow run-out model

Abstract Parameter calibration is one of the most problematic phases of numerical modeling since the choice of parameters affects the model\u2019s reliability as far as the physical problems being studied are concerned. In some cases, laboratory tests or physical models evaluating model parameters cannot be completed and other strategies must be adopted; numerical models reproducing debris flow propagation are one of these. Since scale problems affect the reproduction of real debris flows in the laboratory or specific tests used to determine rheological parameters, calibration is usually carried out by comparing in a subjective way only a few parameters, such as the heights of soil deposits calculated for some sections of the debris flows or the distance traveled by the debris flows using the values detected in situ after an event has occurred. Since no automatic or objective procedure has as yet been produced, this paper presents a numerical procedure based on the application of a statistical algorithm, which makes it possible to define, without ambiguities, the best parameter set. The procedure has been applied to a study case for which digital elevation models of both before and after an important event exist, implicating that a good database for applying the method was available. Its application has uncovered insights to better understand debris flows and related phenomena

Silver as antibacterial toward Listeria monocytogenes

Listeria monocytogenes is a serious foodborne pathogen that can contaminate food during processing and can grow during food shelf-life. New types of safe and effective food contact materials embedding antimicrobial agents, like silver, can play an important role in the food industry. The present work aimed at evaluating the in vitro growth kinetics of different strains of L. monocytogenes in the presence of silver, both in its ionic and nano form. The antimicrobial effect was determined by assaying the number of culturable bacterial cells, which formed colonies after incubation in the presence of silver nanoparticles (AgNPs) or silver nitrate (AgNO(3)). Ionic release experiments were performed in parallel. A different reduction of bacterial viability between silver ionic and nano forms was observed, with a time delayed effect exerted by AgNPs. An association between antimicrobial activity and ions concentration was shown by both silver chemical forms, suggesting the major role of ions in the antimicrobial mode of action

Towards sustainable development of the coastal resources of Lingayen Gulf, Phlilppines

Coastal zone management, Resource development, Philippines, Lingayen Gulf,

Ion-selective carbon-paste electrodes for halides and silver(I) ions

The behaviour of a simple type of ion-selective electrode for halogens and silver has been studied. The electrode consists of a plastic body filled with carbon paste, the surface of which can be easily renewed. The paste composition is based on carbon-nujol (5:1, w/v) or carbon-paraffin wax (3:1,w/w) containing a prepared mixture of silver halide-silver sulphide (1–30%). The electrodes have low ohmic resistance and show a rapid Nernstian response (within 2–5 mV) for halide and silver ions down to 5·10-5 M chloride, 1·10-5 M bromide and 5·10-7 M iodide with the respective electrodes. Ions forming very stable complexes with halide or silver and those having strong oxidizing or reducing action interfere