Multi-Atomic Mirror for Perfect Reflection of Single Photons in A Wide Band of Frequency

A resonant two level atom doped in one dimensional waveguide behaves as a mirror, but this single-atom "mirror" can only reflect single photon perfectly at a specific frequency. For a one dimensional coupled-resonator waveguide, we propose to extend the perfect reflection region from a specific frequency to a wide band by placing many atoms individually in the resonators in a finite coordinate region of the waveguide. Such a doped resonator array promises us to control the propagation of a practical photon wave packet with certain momentum distribution instead of a single photon, which is ideally represented by a plane wave with specific momentum. The studies based on the discrete-coordinate scattering theory display that such hybrid structure indeed provides a near-perfect reflection for single photon in a wide band. We also calculated photon group velocity distribution, which shows that the perfect reflection with wide band exactly corresponds to the stopping light region.Comment: 8 pages, 10 figure

Heavy Metals in Liming Materials from NW Croatia: Possible Effect of Liming on Permissible Contents of Heavy Metals in Arable Soil

The evaluation of the heavy metal discharge from liming materials into the arable soil in NW Croatia is based upon the contents of Fe, Mn, Pb, Cu, Zn, Cd, Co and Hg in the studied carbonate raw materials, obtained under simulated conditions of the lowest presumed acidity (pH>3) which can occur in the agroecological environment. From the agroecological viewpoint, the heavy metal contents of the analyzed liming materials are much lower than the permissible levels. Only cadmium contents indicate that a certain amount of care should be taken into account. Because cadmium is bound in labile forms (pH>3 soluble fraction), it has to be considered quite mobile and biologically available in limed arable soils that are affected by drastic pH changes in the agroecological environment

Energy expenditure in female workers in a textile factory

Autori su ispitivali energetske rashode radnica na tri radna mjesta, i to: šivanje električnim strojem, krojenje električnom pilom i rad na tkalačkom stroju za izradu vrpce. Ispitivanja su vršena standardnim metodama, određivanjem energetskih ekvivalenata za pojedine specifične radnje, izradom vremenskih tablica i preračunavanjem utrošenih kalorija po pojedinim radnim satima. Utrošeno radno vrijeme podijeljeno je na djelatnosti A, B i C. A = rad, osnovni za radno mjesto, B = priprema za izvršavanje osnovnog rada i C = odmor spontani i službeni. Energetska rashodi radnica u tekstilnoj industriji pokazuju velike razlike (do 500 kal.) po pojedinim radnim mjestima. Taj podatak omogućava da se i u ovakvim pogonima lake industrije izvrši diferencijacija radnih mjesta po njihovoj energetskoj opterećenosti. Osim toga ističu potrebu da se ispita mogućnost poboljšanja samog rada, kako bi se uz manji energetski utrošak mogao postići isti radni efekt.The authors have studied the problem of energy expenditure in female workers in a textile factory, by using standard methods. Data evaluated so far show that there is a great difference in energy expenditure for different works in this factory. lt is possible to differentiate the heaviness of work done in this industry, and it is necessary to investigate what should be done to reduce the energy expenditure to a lower level

Energy expenditure in textile workers

Određivani su energetski ekvivalenti za pojedine aktivnosti u tekstilnoj industriji. Ispitivanje je izvršeno kod 17 radnika i radnika poduzeća »Nada Dimić« u Zagrebu. Ukupno je ispitano 80 uzoraka izdahnutog zraka za devet aktivnosti specifičnih za takvo poduzeće. Analiza izdahnutog zraka vršena je metodom po Scholanderu. Dobiveni energetski ekvivalenti pokazuju da je raspon kalorija koje se troše za pojedine radnje dosta velik, pa da u prosjeku varira od 1,56 do 5,63 kal/min, ali se većina radova nalazi na donjoj granici rashoda.The examination of energy expenditure requirement was carried out in a textile factory in Zagreb. 17 workers, women and men, were examined by a Franz-Müller respirometer. Expired air samples were taken and analysed after Scholander. The results shown in calories per minute include values for basal metabolism. The energy expenditure was high only in few cases; in all others the values were very low, corresponding to the values obtained by other authors

Environmentally Friendly Packaging Materials Based on Thermoplastic Starch

Low-density polyethylene (LDPE) is extensively used as packaging material, and as such has a short service life, but long environmental persistence. The alternative to reducing the impact of LDPE as packaging material on the environment is to blend it with carbohydrate-based polymers, like starch. Therefore, the focus of this investigation was to prepare bio-based blends of LDPE and thermoplastic starch (TPS) containing different amounts of TPS using a Brabender kneading chamber. Due to incompatibility of LDPE/TPS blends, a styrene–ethylene/butylene–styrene block copolymer, grafted with maleic anhydride (SEBS-g-MA) containing 2 mol % anhydride groups, was added as a compatibilizer. The effect of the biodegradable, hydrophilic TPS, its content, and the incorporation of the compatibilizer on the properties of LDPE/TPS blends were analysed. The characterization was performed by means of thermogravimetric analysis (TG), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and water absorption (WA). Based on the results of the morphological structure, a good dispersion of the TPS phase in LDPE matrix was obtained with the incorporation of compatibilizer, which resulted in better thermal and barrier properties of these materials

Urine-based testing for Chlamydia trachomatis among young adults in a population-based survey in Croatia: Feasibility and prevalence

<p>Abstract</p> <p>Background</p> <p>We assessed the feasibility of collecting urine samples for testing on genital <it>Chlamydia trachomatis </it>infection in a population-based survey, and prevalence of this infection among young people aged 18-25 in Croatia. In Croatia, as in the other countries of Eastern Europe, there is a lack of data on prevalence of <it>C trachomatis </it>in the general population, including young adults.</p> <p>Methods</p> <p>We sampled participants using a nationally representative, multi-stage stratified probability sample of young men and women. Detection of <it>C trachomatis </it>DNA in urine samples was performed by using a real-time PCR assay COBAS^®TaqMan^®CT Test, v2.0.</p> <p>Results</p> <p>Overall, 1005 young adults participated in the behavioural part of the survey, and 27.9% men and 37.5% women who were sexually experienced agreed to provide urine samples for testing on <it>C trachomatis</it>. Using multivariate analysis, women were significantly more likely to provide urine samples than men (aOR = 1.53, 95% CI 1.14-2.06) as were those who reported no condom use at last intercourse (aOR = 1.95, 95% CI 1.44-2.62). Prevalence of <it>C trachomatis </it>infection among those who were sexually experienced was 7.3% in men and 5.3% in women.</p> <p>Conclusions</p> <p>Population-based surveys that use probabilistic sampling are a feasible way to obtain population estimates of <it>C trachomatis </it>prevalence among young adults in Croatia, but it is challenging to obtain an adequate response rate. The prevalence of <it>C trachomatis </it>among young adults in Croatia found in this study was higher than that found in other European countries with similar survey response rates.</p

Organoklorirani pesticidi u slatkovodnim ribama zagrebačkog područja

The aim of this study was to determine the level of organochlorine pesticides in freshwater fish from the Zagreb area, Croatia. The study included 215 freshwater fish samples from three sites: the Sava River, Lake Jarun, and five fishponds from the Zagreb surroundings. Organochlorine pesticides DDT and derivates, HCH, HCB, lindane, aldrin, dieldrin, endrin, heptachlor with epoxide, and methoxychlor were determined using the GC-ECD method. The determined amounts of organochlorine pesticides were within allowed concentration limits in all analysed fish samples. Median values ranged from below the detection limit of 0.01 µg kg-1 for dieldrin and metoxychlor to 2.00 µg kg-1 for DDT in the Cyprinidae fish family from the Sava River, Zagreb sampling site (group 1). This study has confirmed pesticide persistence in the overall ecosystem in our country despite the ban of some thirty years ago, like in many other parts of the world.Cilj istraživanja bio je utvrditi količinu organokloriranih pesticida u slatkovodnim ribama zagrebačkog područja. Obrađeno je ukupno 215 uzoraka slatkovodne ribe sa sljedećih triju lokacija: rijeka Sava, jezero Jarun i pet tzv. ekoloških jezera u okolici Zagreba. Organoklorirani pesticidi DDT i derivati, HCH izomeri (α-HCH, β-HCH and δ-HCH), HCB, lindan (γ-HCH), aldrin, dieldrin, endrin, heptaklor, heptaklorepoksid i metoksiklor) određivali su se metodom plinske kromatografije uz elektronapsorpcijski način detekcije i uz postignutu granicu detekcije od 0,01 µg kg-1. Vrijednosti ispitivanih organokloriranih pesticida u svim su uzorcima riba bile mnogo niže od maksimalno dopuštenih koncentracija. Vrijednosti medijana kretale su se od najnižih 0,01 µg kg-1 za dieldrin i metoksiklor do najviših 2,00 µg kg-1 za DDT u uzorcima riba porodice Cyprinidae s lokacije Sava - Zagreb. Utvrđeni ostaci preostalih ispitivanih pesticida potvrđuju kako njihovu uporabu na našim područjima tako i njihovu postojanost i prisutnost u cjelokupnom ekosustavu unatoč činjenici da je većina zabranjena u Hrvatskoj prije gotovo 30 godina, kao i u mnogim dijelovima svijeta