Coherence loss and revivals in atomic interferometry: A quantum-recoil analysis

The coherence effects induced by external photons coupled to matter waves inside a Mach-Zehnder three-grating interferometer are analyzed. Alternatively to atom-photon entanglement scenarios, the model considered here only relies on the atomic wave function and the momentum shift induced in it by the photon scattering events. A functional dependence is thus found between the observables, namely the fringe visibility and the phase shift, and the transversal momentum transfer distribution. A good quantitative agreement is found when comparing the results obtained from our model with the experimental data.Comment: 18 pages, 4 figure

On Wheeler's delayed-choice Gedankenexperiment and its laboratory realization

Here, we present an analysis and interpretation of the experiment performed by Jacques et al. (2007 Science 315, 966), which represents a realization of Wheeler's delayed-choice Gedankenexperiment. Our analysis is based on the evolution of the photon state, since the photon enters into the Mach-Zehnder interferometer with a removable beam-splitter until it exits. Given the same incident photon state onto the output beam-splitter, BS_output, the photon's state at the exit will be very different depending on whether BS_output is on or off. Hence, the statistics of photon counts collected by the two detectors, positioned along orthogonal directions at the exit of the interferometer, is also going to be very different in either case. Therefore, it is not that the choice of inserting (on) or removing (off) a beam-splitter leads to a delayed influence on the photon behavior before arriving at the beam-splitter, but that such a choice influences the photon state at and after BS_output, i.e., after it has exited from the Mach-Zehnder interferometer. The random on/off choice at BS_output has no delayed effect on the photon to behave as a wave or a corpuscle at the entrance and inside the interferometer, but influences the subsequent evolution of the photon state incident onto BS_output.Comment: 7 pages, 4 figure

E-shopping Across EU – Why Some Individuals Refuse to Adopt It?

Despite many advantages of e-commerce for both firms and buyers, it is still not equally adopted by customers in all European Union countries. According to Digital Scoreboard in countries such as United Kingdom and Denmark, nearly 90% of Internet users shop online. On the other hand, in Romania and Bulgaria, not even one-third of the Internet users buy goods and services online. Diffusion of e-shopping clearly has different pace across EU. In this article, we focus on individuals who refuse to purchase over Internet and aim to explore reasons for their behavior. To do so, we rely on Community Statistics on Information Society (CSIS) microdata for the year 2015. Individuals who report ordering and buying over the Internet more than one year ago and those who never engaged in online shopping were asked about reasons for not buying online. Potential reasons include lack of skills, privacy and security concerns, delivery concerns and problems, not having payment cards as well as habit, loyalty and preference of shopping in stores. The focus of this article is on comparison of reasons for not shopping online of individuals in EU countries that lead in adoption of e-shopping with laggard countries. We first analyze the prevalence of reasons for not buying online and compare countries in that respect. Among individuals who did not adopt e-shopping, there are those who have tried it at one point in time and did not continue to use it frequently and those who actually never engaged in buying over Internet. Both have certain reasons and constrains that prevent them from adopting this form of shopping. The analysis is followed by identification of reasons that significantly affect probability of trying online shopping, if not adopting it fully. It can be assumed that gaining true experience might contribute to increase in adoption of e-shopping among individuals. This is even more important for countries that still lag behind not just in buying online but in overall digital performance.     Keywords: e-shopping, adoption, customers, European Unio

Supplementary data for article: Lončar, N.; Slavić, M. Š.; Vujčić, Z.; Božić, N. Mixed-Mode Resins: Taking Shortcut in Downstream Processing of Raw-Starch Digesting α-Amylases. Scientific Reports 2015, 5. https://doi.org/10.1038/srep15772

Supplementary material for: [https://doi.org/10.1038/srep15772]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1985

Mixed-mode resins: taking shortcut in downstream processing of raw-starch digesting alpha-amylases

Bacillus licheniformis 9945a alpha-amylase is known as a potent enzyme for raw starch hydrolysis. In this paper, a mixed mode Nuvia cPrime (TM) resin is examined with the aim to improve the downstream processing of raw starch digesting amylases and exploit the hydrophobic patches on their surface. This resin combines hydrophobic interactions with cation exchange groups and as such the presence of salt facilitates hydrophobic interactions while the ion-exchange groups enable proper selectivity. alpha-Amylase was produced using an optimized fed-batch approach in a defined media and significant overexpression of 1.2 g L-1 was achieved. This single step procedure enables simultaneous concentration, pigment removal as well as purification of amylase with yields of 96% directly from the fermentation broth.Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3384

On the influence of resonance photon scattering on atom interference

Here, the influence of resonance photon-atom scattering on the atom interference pattern at the exit of a three-grating Mach-Zehnder interferometer is studied. It is assumed that the scattering process does not destroy the atomic wave function describing the state of the atom before the scattering process takes place, but only induces a certain shift and change of its phase. We find that the visibility of the interference strongly depends on the statistical distribution of transferred momenta to the atom during the photon-atom scattering event. This also explains the experimentally observed (Chapman et al 1995 Phys. Rev. Lett. 75 2783) dependence of the visibility on the ratio d_p/\lambda_i = y'_{12} (2\pi/kd\lambda_i), where y'_{12} is distance between the place where the scattering event occurs and the first grating, k is the wave number of the atomic center-of-mass motion, $d$ is the grating constant and \lambda_i is the photon wavelength. Furthermore, it is remarkable that photon-atom scattering events happen experimentally within the Fresnel region, i.e. the near field region, associated with the first grating, which should be taken into account when drawing conclusions about the relevance of "which-way" information for the interference visibility.Comment: 9 pages, 1 figur

Uporedna analiza izoformi α-amilaze iz srednjeg creva larvi Cerambyx cerdo L. (Coleoptera: Cerambycidae) iz prirode i gajenih na veštačkoj podlozi

alpha-Amylase isoforms of Cerambyx cerdo larvae from the wild (ML and SL) and reared in the laboratory (ADL) were compared. Three amylase isoforms were presented in the SL and ML extracts while two isoforms were presented in the ADL according to zymogram after isoelectric focusing (IEF). All C. cerdo amylase isoforms were acidic proteins (pI lt 3.5). Seven amylase isoforms (ACC 1-7) from the midgut of C. cerdo larvae were found in the ML midgut extract, six in the SL extract, and four in the ADL extract according to native PAGE zymogram. The ADL amylase had the highest activity. All crude midgut extracts of C. cerdo larvae were fractionated on a Superose 12 HR column. The molecular mass of the ACC was estimated to be 34 kDa.Upoređene su izoforme α-amilaze larvi Cerambyx cerdo sakupljenih iz prirode (ML i SL) i gajenih na veštačkoj podlozi u laboratoriji (ADL). Zimogramskom detekcijom posle IEF-a po tri izoforme su detektovane u ML i SL ekstraktima, a u ADL dve izoforme. Sve amilazne izoforme iz C. cerdo su bile kisele (pI lt 3.5). Zimogramskom detekcijom posle nativne elektroforeze sedam izoformi je detektovano u ML ekstraktu, šest u SL ekstraktu i četiri u ADL ekstraktu. Najveća amilazna aktivnost je detektovana u ADL ekstraktu. Svi ekstrakti srednjih creva larvi C. cerdo su frakcionisani na koloni Superose 12 HR. Molekulska masa ACC-a je bila 34 kDa

Properties and nature of Be stars 30. Reliable physical properties of a semi-detached B9.5e+G8III binary BR CMi = HD 61273 compared to those of other well studied semi-detached emission-line binaries

Reliable determination of the basic physical properties of hot emission-line binaries with Roche-lobe filling secondaries is important for developing the theory of mass exchange in binaries. It is a very hard task, however, which is complicated by the presence of circumstellar matter in these systems. So far, only a small number of systems with accurate values of component masses, radii, and other properties are known. Here, we report the first detailed study of a new representative of this class of binaries, BR CMi, based on the analysis of radial velocities and multichannel photometry from several observatories, and compare its physical properties with those for other well-studied systems. BR CMi is an ellipsoidal variable seen under an intermediate orbital inclination of ~51 degrees, and it has an orbital period of 12.919059(15) d and a circular orbit. We used the disentangled component spectra to estimate the effective temperatures 9500(200) K and 4655(50) K by comparing them with model spectra. They correspond to spectral types B9.5e and G8III. We also used the disentangled spectra of both binary components as templates for the 2-D cross-correlation to obtain accurate RVs and a reliable orbital solution. Some evidence of a secular period increase at a rate of 1.1+/-0.5 s per year was found. This, together with a very low mass ratio of 0.06 and a normal mass and radius of the mass gaining component, indicates that BR CMi is in a slow phase of the mass exchange after the mass-ratio reversal. It thus belongs to a still poorly populated subgroup of Be stars for which the origin of Balmer emission lines is safely explained as a consequence of mass transfer between the binary components.Comment: 17 pages, 5 figures, accepted for publication in Astronomy and Astrophysics. appears in Astronomy and Astrophysics 201

Supplementary data for the article: Loncar, N.; Bozic, N.; Vujcic, Z. Expression and Characterization of a Thermostable Organic Solvent-Tolerant Laccase from Bacillus Licheniformis ATCC 9945a. J. Mol. Catal. B-Enzym. 2016, 134, 390–395. https://doi.org/10.1016/j.molcatb.2016.06.005

Supplementary material for: [https://doi.org/10.1016/j.molcatb.2016.06.005]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2375]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3517

Uklanjanje fenola i fenolnih derivata iz vode imobilizovanom polifenol-oksidazom iz krompira

Phenols containing halogens, which tend to deactivate the aromatic nuclei, constitute a significant category of highly toxic and difficult-to-degrade pollutants, which arise from a wide variety of industries. The main purpose of this study was to obtain an inexpensive immobilized enzyme for the removal of phenols. Partially purified potato polyphenol oxidase (PPO) was immobilized onto different commercial and laboratory produced carriers. Three of the obtained biocatalysts, with the highest PPO activities, namely Eupergit C250L-PPO; Celite-PPO and CelluloseM-PPO, were tested in a batch reactor for the removal of phenol, 4-chlorophenol and 4-bromophenol. In the case of 2.5 mM substrates with Eupergit C250L-PPO, an around 45 % removal of 4-bromophenol was achieved, while the removals 4-chlorophenol and phenol were 35 and 20 %, respectively. The reusability of Eupergit C250L-PPO for the removal of 4-chlorophenol was tested. After eight repeated tests, the efficiency of 4-chlorophenol removal by Eupergit C250L-PPO immobilisate had decreased to 55 %.Halogenovani fenoli imaju dezaktivirano aromatično jezgro i čine značajnu kategoriju veoma toksičnih i teško razgradivih zagađivača u raznim industrijskim granama. Glavni cilj ovog rada je bio dobijanje jeftinog imobilizovanog enzima za uklanjanje fenola. Delimično prečišćena polifenol-oksidaza (PFO) iz krompira je imobilizovana na različitim komercijalnim i laboratorijski sintetizovanim nosačima. Od dobijenih biokatalizatora, tri sa najvećim aktivnostima PPO, nazvani Eupergit C250L-PFO; Celit-PFO i CelulozaM-PFO, testirani su u reaktoru za uklanjanje fenola, 4-hlorfenola i 4-bromfenola. U slučaju 2,5 mM supstrata sa Eupergit C250L-PFO, postignuto je oko 45 % razgradnje 4-bromfenola, dok su 4-hlorfenol i fenol razgrađeni 35, odnosno 20 %. Testirana je i sposobnost višestruke upotrebe Eupergit C250L-PFO imobilizata za uklanjanje 4-hlorfenola. Nakon osam ponovljenih ciklusa efikasnost Eupergit C250L-PFO imobilizata za uklanjanje 4-hlorfenola je pala na 55%