Sloshing of Cryogenic Helium Driven by Lateral Impulse/Gravity Gradient-Dominated/or g-Jitter-Dominated Accelerations and Orbital Dynamics

The coupling of slosh dynamics within a partially filled rotating dewar of superfluid helium 11 with spacecraft orbital dynamics is investigated in response to the environmental disturbances of (a) lateral impulses, (b) gravity gradients and (c) g-jitter forces. The purpose of this study is to investigate how the coupling of helium 11 fluid slosh dynamics driven by three cases of environmental force with spacecraft dynamics can affect the bubble deformations and their associated fluid and spacecraft mass centre fluctuations. The numerical computation of slosh dynamics is based on a rotational frame, while the spacecraft dynamics is associated with a non-rotational frame. Results show that the major contribution of orbital dynamics is driven by coupling with slosh dynamics. Neglecting the effect of slosh dynamics acting on the spacecraft may lead to the wrong results for the development of orbital and attitude control techniques

Coulomb effects on the formation of proton halo nuclei

The exotic structures in the 2s_{1/2} states of five pairs of mirror nuclei ^{17}O-^{17}F, ^{26}Na-^{26}P, ^{27}Mg-^{27}P, ^{28}Al-^{28}P and ^{29}Si-^{29}P are investigated with the relativistic mean-field (RMF) theory and the single-particle model (SPM) to explore the role of the Coulomb effects on the proton halo formation. The present RMF calculations show that the exotic structure of the valence proton is more obvious than that of the valence neutron of its mirror nucleus, the difference of exotic size between each mirror nuclei becomes smaller with the increase of mass number A of the mirror nuclei and the ratios of the valence proton and valence neutron root-mean-square (RMS) radius to the matter radius in each pair of mirror nuclei all decrease linearly with the increase of A. In order to interpret these results, we analyze two opposite effects of Coulomb interaction on the exotic structure formation with SPM and find that the contribution of the energy level shift is more important than that of the Coulomb barrier for light nuclei. However, the hindrance of the Coulomb barrier becomes more obvious with the increase of A. When A is larger than 34, Coulomb effects on the exotic structure formation will almost become zero because its two effects counteract with each other.Comment: 9 pages, 6 figures. One colum

Hundredfold Enhancement of Light Emission via Defect Control in Monolayer Transition-Metal Dichalcogenides

Two dimensional (2D) transition-metal dichalcogenide (TMD) based semiconductors have generated intense recent interest due to their novel optical and electronic properties, and potential for applications. In this work, we characterize the atomic and electronic nature of intrinsic point defects found in single crystals of these materials synthesized by two different methods - chemical vapor transport and self-flux growth. Using a combination of scanning tunneling microscopy (STM) and scanning transmission electron microscopy (STEM), we show that the two major intrinsic defects in these materials are metal vacancies and chalcogen antisites. We show that by control of the synthetic conditions, we can reduce the defect concentration from above $10^{13} /cm^2$ to below $10^{11} /cm^2$. Because these point defects act as centers for non-radiative recombination of excitons, this improvement in material quality leads to a hundred-fold increase in the radiative recombination efficiency

Combinatorial RNA Design: Designability and Structure-Approximating Algorithm

In this work, we consider the Combinatorial RNA Design problem, a minimal instance of the RNA design problem which aims at finding a sequence that admits a given target as its unique base pair maximizing structure. We provide complete characterizations for the structures that can be designed using restricted alphabets. Under a classic four-letter alphabet, we provide a complete characterization of designable structures without unpaired bases. When unpaired bases are allowed, we provide partial characterizations for classes of designable/undesignable structures, and show that the class of designable structures is closed under the stutter operation. Membership of a given structure to any of the classes can be tested in linear time and, for positive instances, a solution can be found in linear time. Finally, we consider a structure-approximating version of the problem that allows to extend bands (helices) and, assuming that the input structure avoids two motifs, we provide a linear-time algorithm that produces a designable structure with at most twice more base pairs than the input structure.Comment: CPM - 26th Annual Symposium on Combinatorial Pattern Matching, Jun 2015, Ischia Island, Italy. LNCS, 201

Effect of electron irradiation on the transformation characteristics of narrow hysteresis TiNiCu shape memory alloys

TiNiCu shape memory alloy samples were irradiated by 1.7 MeV electrons below the martensite finish temperature Mf.Mf. The transformation temperatures and the latent heat of phase transformation were measured by differential scanning calorimeter. The damage accumulation was determined by positron annihilation technology. The results indicated that the austenite transformation temperatures were raised, and the hysteresis was increased by the irradiation. The electron irradiation had a slight effect on Mf,Mf, and no detectable effect on the martensitic transformation start temperature Ms.Ms. The second lifetime of positrons were increased by the electron irradiation indicating the increase in the size and amount of vacancy clusters, which contributed to the observed change of the transformation characteristics. © 2002 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70937/2/APPLAB-80-1-31-1.pd

Assessment of the determinant of choice of ‘over the counter’ analgesics among students of a university in Abbottabad, Pakistan

Purpose: To ascertain the preference of COMSATS Institute of Information Technology, Abbottabad, Pakistan (CIIT) students for various ‘over the counter’ analgesics.Methods: This cross-sectional survey study on self-medication of ibuprofen in students of CIIT was conducted in July - August 2013 using a self-administered questionnaire. Five hundred students with an average age of 20 - 25 years cooperated in this inquisition. The questionnaire contained 18 questions including socio-demographic queries, economical status, perception of the frequency of pain, their locality, and behavior and knowledge of participants on the use of ibuprofen regarding its therapeutic and adverse effects, and interactions.Results: Out of the 500 participants in the study, 70.4 % were female. The response rate was 68.2 %. Ibuprofen (54 %) was the most used analgesic of all the NSAIDs among the respondents. Approximately, 11.2 % of the respondents reported that they suffer from pain almost every day. The younger and more educated respondents had better level of awareness about the ibuprofen’s indications as compared to those who had low level of education. Of the respondents, 29.6 % were not aware of any side effect caused by ibuprofen. Approximately, 22.4 % of the respondents had no knowledge of the interactions of ibuprofen while 61.2 % of the participants consult a physician about painkillers.Conclusion: Although many of the students undergo almost daily pain and favor ibuprofen over other NSAIDs analgesics among but they still lack information on its appropriate handling and safety. The overall result of the survey indicates very low level of information about the drug interaction.Keywords: Pain, OTC, analgesic, ibuprofen, questionnaire based survey, awarenes

Highly sensitive and selective Love mode surface acoustic wave ammonia sensor based on graphene oxides operated at room temperature

It is crucial to develop highly sensitive and selective sensors for ammonia, one of the most common toxic gases which have been widely used in pharmaceutical, chemical and manufacturing industries. In this study, graphene oxide (GO) film was spin-coated onto surfaces of ST-cut quartz surface acoustic wave (SAW) devices with a resonant frequency of 200 MHz for ammonia sensing. The oxygen-containing functional groups (such as hydroxyl and epoxy ones) on the surface of GO film strongly absorb ammonia molecules and thus increase the film stiffness. This is attributed to the main ammonia sensing mechanism of the Love mode SAW devices, which show not only a positive frequency shift of 620 Hz for 500 ppb ammonia gas, but also an excellent selectivity (as compared to other gases such as H2, H2S, CO and NO2) and a good reproducibility, operated at room temperature of 22 oC