Multiple radial phosphorus segregations in GaAsP core-shell nanowires

Highly faceted geometries such as nanowires are prone to form self-formed features, especially those that are driven by segregation. Understanding these features is important in preventing their formation, understanding their effects on nanowire properties, or engineering them for applications. Single elemental segregation lines that run along the radii of the hexagonal cross-section have been a common observation in alloy semiconductor nanowires. Here, in GaAsP nanowires, two additional P rich bands are formed on either side of the primary band, resulting in a total of three segregation bands in the vicinity of three of the alternating radii. These bands are less intense than the primary band and their formation can be attributed to the inclined nanofacets that form in the vicinity of the vertices. The formation of the secondary bands requires a higher composition of P in the shell, and to be grown under conditions that increase the diffusivity difference between As and P. Furthermore, it is observed that the primary band can split into two narrow and parallel bands. This can take place in all six radii, making the cross sections to have up to a maximum of 18 radial segregation bands. With controlled growth, these features could be exploited to assemble multiple different quantum structures in a new dimension (circumferential direction) within nanowires.

Auxospore wall structure and postsexual valve morphology in Rhabdonema minutum Kützing

Several decades ago, three members of the araphid pennate genus Rhabdonema (R. adriaticum, R. arcuatum, R. minutum) were the first araphid diatoms studied using cultures and electron microscopical methods to determine auxospore structure and development. Of these, R. minutum was the least documented at that time. None have been reinvestigated until now. Here we present the structural elements of the mature auxospore and the initial and postsexual valve characteristics of R. minutum. Although in general the auxospore wall of this diatom is similar to that of the two other species examined (to the extent that they were documented), there are intriguing differences. Most unanticipated is the structure of the primary band of the longitudinal perizonium, which shows remarkable similarities to the raphid pennate diatom valve. The evolutionary implications of such a similarity are considered.

Design of Dual Band Circular Microstrip Patch Antenna with Slot for WLAN Applications

A composite double - band circular microstrip patch (MPA) with space opening for WLAN is intended. An investigated configuration is feasible for WLAN applications. An investigated configuration includes the circular patch and π - space resonator. The compact in the antenna size for the lower band is attained by adopting a π – shaped opening space on the ground plane. By balancing the model specifications, a circular patch resonator act at the primary band (5.2 GHz) and the π - space slot act at the secondary band (2.4 GHz), while using the substrate substantial FR4 whichever carry dielectric constant of 4.4 (ɛr). The arranged antenna configuration has small in size, less weight, reduced cost and acceptable isolation. Designed structure presents the return loss less than -10 B and it is indicated with significant impedance matching, improved radiation pattern and good VSWR around 1 over the working bands. The investigated configuration is simulated and analyzed with HFSS.

MOLECULAR ABSORPTION SPECTROSCOPY IN THE UV-VIS REGION FOR THE QUINOLINE-N-OXIDE, NICOTINAMIDE-N-OXIDE AND 2,2-DITHIOBISPYRIDINE-N-OXIDE LIGANDS

The purpose of this study was to analyze and quantify spectral parameters, the absorption bands, specifically in the uv-visible region of some N-oxide ligands. From the spectra, the area under the absorption band, the molar absorptivity, the integrated absorption coefficient and the oscillator strength by the Gaussian approximation method were calculated for each of them, using the proposed evaluation by Drago and Figgs. According to the obtained results, it can be concluded that the heterocyclic compounds studied absorb very well electromagnetic radiation in the ultraviolet region. For the ligands QUI-NO and NIC-NO it was observed that there are two types of bands, primary and secondary, being transitions of type π → π * and n → π*, respectively. For DITBIS-NO, there was only one primary band (transition 1) and two additional shoulders, which had the highest observed absorbance coefficient. These ligands are expected as potential electron donors in complex systems whose purpose is to change the energy levels of the electronic system in order to promote a better utilization of the absorbed energy and therefore a better efficiency.

Performance Evaluation of AIC Technique for Single and Multiple Primary Bands in OFDM based Cognitive Radios

Cognitive radio has emerged as an efficient approach to address the problem of spectrum under-utilization. OFDM has been proposed as a potential candidate for the physical layer of cognitive radios due to its inherent characteristics of spectrum shaping, spectrum analysis and robustness to frequency selective fading. One of the major problems of OFDM is high Out Of Band Radiation (OOBR). This is an undesired phenomenon especially if the nearby band is occupied by primary (or licensed) user. Among the proposed techniques to overcome this problem, Active Interference Cancellation (AIC) is considered to be one of the efficient techniques. In this paper, we evaluate the performance of this technique for single and multiple primary bands in OFDM based cognitive radios. For the case of single primary band, it is shown through simulations that narrower primary bands and use of more number of cancellation carriers increases the OOBR reduction in the desired band. For the case of multiple primary bands, the AIC technique is shown to provide better OOBR reduction for larger inter primary band spacing, lesser number of primary bands and more number of cancellation carriers. We also evaluate the bandwidth efficiency for single and multiple primary bands. The bandwidth efficiency shows a linear decrease with the increase in number of cancellation carriers. Multiple primary band system has more bandwidth efficiency degradation than the single primary band system.

Smallpox vaccines induce antibodies to the immunomodulatory, secreted vaccinia virus complement control protein

Vaccination with Dryvax elicits a broad humoral response against many viral proteins. Human vaccinia immune globulin was used to screen the secreted proteins from cells infected with Dryvax or the candidate smallpox vaccine LC16m8 to determine whether the protective humoral response included antibodies against secreted viral proteins. Many proteins were detected, with the primary band corresponding to a band of 28 or 30 kDa in cells infected with Dryvax or LC16m8, respectively. This was identified as the vaccinia virus complement protein (VCP), which migrated more slowly in LC16m8-infected cells due to post-translational glycosylation. Vaccinia virus deleted in VCP, vVCPko, protected mice from a lethal intranasal challenge of vaccinia Western Reserve strain. Mice vaccinated with purified VCP demonstrated a strong humoral response, but were not protected against a moderate lethal challenge of vaccinia virus, suggesting that the humoral response against VCP is not critical for protection.

Band Gap Formation in Composite Models With Quasi-Random Fiber Arrangements

Large-scale deterministic simulations are performed in order to observe the band gap formation in composite models having quasi-random fiber arrangements. Composite plates are modeled in two-dimensions with various unidirectional fiber arrangements. The quasi-random fiber arrangements can be qualified as essentially regular with slight randomness. Simulation results are compared with the corresponding case of ideally regular fiber arrangement. The most interesting observation is that the slight randomness in the fiber arrangements enhances the band gap phenomenon by introducing a few secondary band gaps adjacent to the primary band gap. An attempt is made to relate the band gap characteristics to the statistical parameters of fiber arrangements.

LIGHT ABSORPTION STUDIES: PART VIII. THE SECONDARY BAND OF ACETOPHENONES AND BENZOIC ACIDS IN ULTRAVIOLET SPECTRA

The absorption spectra of some acetophenones and benzoic acids have been measured in different solvents in the region 220–400 mμ. The two major bands are compared and it is found that steric interactions which considerably alter the high-intensity band have less and somewhat different effects on the secondary band. Solvent effects and the changes observed on substitution indicate that the weaker band (C-band) is essentially of similar character to the high intensity primary band (B-band). A unifying hypothesis to account for the observed changes is presented.