Identification of fullerene-like CdSe nanoparticles from optical spectroscopy calculations

Semiconducting nanoparticles are the building blocks of optical nanodevices as their electronic states, and therefore light absorption and emission, can be controlled by modifying their size and shape. CdSe is perhaps the most studied of these nanoparticles, due to the efficiency of its synthesis, the high quality of the resulting samples, and the fact that the optical gap is in the visible range. In this article, we study light absorption of CdSe nanostructures with sizes up to 1.5 nm within density functional theory. We study both bulk fragments with wurtzite symmetry and novel fullerene-like core-cage structures. The comparison with recent experimental optical spectra allows us to confirm the synthesis of these fullerene-like CdSe clusters

Light-front field theories at finite temperature

We study the question of generalizing light-front field theories to finite temperature. We show that the naive generalization has serious problems and we identify the source of the difficulty. We provide a proper generalization of these theories to finite temperature based on a relativistic description of thermal field theories, both in the real and the imaginary time formalisms. Various issues associated with scalar and fermion theories, such as non-analyticity of self-energy, tensor decomposition are discussed in detail.Comment: 11 pages, 4 figures, Revtex

Effects of High Intensity Ultrasound Frequency and High-Speed Agitation on Fat Crystallization

The objective of this research was to examine the effect of ultrasound frequency and high-speed agitation on lipid crystallization. Interesterified soybean oil was crystallized at 44 °C without and with the application of high intensity ultrasound (HIU—20 and 40 kHz) or with high-speed agitation (6000 and 24,000 rpm). Two tip amplitudes (24 and 108 µm) and three pulse durations were evaluated (5, 10, and 15 s) for the acoustic frequencies tested. Sonication at 20 kHz of frequency significantly reduced crystal size, increased (p \u3c 0.05) elasticity (435.9 ± 173.3–80,218 ± 15,384 Pa) and SFC (0.2 ± 0.0–4.5 ± 0.4%). No significant difference was observed in the crystallization behavior of these samples when sonicated at different amplitudes for 5 and 10 s. The crystallization behavior was significantly delayed (p \u3c 0.05) in samples sonicated using 108 µm amplitude for 15 s. Larger crystals were formed in samples sonicated at 40 kHz compared to those obtained with 20 kHz and lower SFC (3.7 ± 0.0%) and elasticity (3943 ± 1459 Pa) values were obtained. High-speed agitation at 24,000 rpm increased SFC (5.5 ± 0.1%) and crystallized area and decreased the elasticity (42,602 ± 11,775 Pa) compared to the samples sonicated at 20 kHz

Social Relations and Methods in Recommender Systems: A Systematic Review

With the constant growth of information, data sparsity problems, and cold start have become a complex problem in obtaining accurate recommendations. Currently, authors consider the user's historical behavior and find contextual information about the user, such as social relationships, time information, and location. In this work, a systematic review of the literature on recommender systems that use the information on social relationships between users was carried out. As the main findings, social relations were classified into three groups: trust, friend activities, and user interactions. Likewise, the collaborative filtering approach was the most used, and with the best results, considering the methods based on memory and model. The most used metrics that we found, and the recommendation methods studied in mobile applications are presented. The information provided by this study can be valuable to increase the precision of the recommendations

Transient Pressures from Compression of Discrete Air Pockets in Rapidly Filling Combined Sewer Storage Tunnels

https://deepblue.lib.umich.edu/bitstream/2027.42/154163/1/39015099114905.pd

Do personality traits and self-regulatory processes affect decision-making tendencies?

Objective: This research attempted to clarify the role played by personality traits and self-regulated motivation in affecting decision-making tendencies. Method: Study 1 (n = 209) examined whether the Big Five personality traits predict minimising, maximising, and satisficing tendencies; Study 2 (n = 460) tested the mediating role of self-regulatory orientations in the relationship between personality traits and decision-making tendencies by performing structural equation modelling with latent variables. Results: Conscientiousness emerged as the strongest positive predictor of maximising, whereas openness to experience, conscientiousness, and agreeableness emerged as negative predictors of satisficing. As for the mediational model, both locomotion and assessment played a role in mediating the relationships between the personality traits and decision-making tendencies. Conclusions: This research provided interesting insights into the underlying motivations and strategies that lead individuals to maximise, satisfice, or minimise

Thermal Operator Representation of Finite Temperature Graphs

Using the mixed space representation (t,p) in the context of scalar field theories, we prove in a simple manner that the Feynman graphs at finite temperature are related to the corresponding zero temperature diagrams through a simple thermal operator, both in the imaginary time as well as in the real time formalisms. This result is generalized to the case when there is a nontrivial chemical potential present. Several interesting properties of the thermal operator are also discussed.Comment: 20 pages, seven figure

Efficient calculation of van der Waals dispersion coefficients with time-dependent density functional theory in real time: application to polycyclic aromatic hydrocarbons

The van der Waals dispersion coefficients of a set of polycyclic aromatic hydrocarbons, ranging in size from the single-cycle benzene to circumovalene (C66H20), are calculated with a real-time propagation approach to time-dependent density functional theory (TDDFT). In the non-retarded regime, the Casimir-Polder integral is employed to obtain C6, once the dynamic polarizabilities have been computed at imaginary frequencies with TDDFT. On the other hand, the numerical coefficient that characterizes the fully retarded regime is obtained from the static polarizabilities. This ab initio strategy has favorable scaling with the size of the system - as demonstrated by the size of the reported molecules - and can be easily extended to obtain higher order van der Waals coefficients.Comment: submitted to J. Chem. Phy

Struktur Histologi Otot Femur Kelinci (Lepus SP.) Setelah Perlakuan Implantasi Material Stainless Steel Aisi 316l Selama 2,5 Bulan

Production implant orthopedic domestic with 316L Stainless steel base material which use the material dimensions of the Indonesian non-import until now hasn't been researched. Research the effect of implantation of these materials to health conditions need to be conducted on animal models, such as the rabbit before it wad applied to humans. This study aims to determine the histological changes in the femoral muscle of rabbits after implantation of AISI 316L stainless steel for 2.5 months, as part of the basic data for further research in order to figure out orthopedic implants that can be used by the body. This study compared the P0: rabbit was not given implantation of stainless steel AISI 316L with P1: Rabbits were given treatment AISI 316L stainless steel implants in the quadriceps femoris muscle parallel to the femur bone. Implantation of the implant material was conducted for 2.5 months. Histological changes observed were the presence or absence of necrosis, fibrosis and tissue cavities in the rabbit femoral muscle tissue. The results showed there were no three variables were observed. It is concluded AISI 316L stainless steel did not cause structural changes in muscle histology in a rabbit femur after implantation for 2.5 months; so that these materials can be used as an implant material in the body

Sonocrystallization of interesterified fats with 20 and 30% of stearic acid at the sn-2 position and their physical blends

Physical blends (PB) of high oleic sunflower oil and tristearin with 20 and 30% stearic acid and their interesterified (IE) products where 20 and 30% of the fatty acids are stearic acid at the sn-2 position crystallized without and with application of high intensity ultrasound (HIU). IE samples were crystallized at supercooling temperatures (ΔT) of 12, 9, 6, and 3 °C while PB were crystallized at ΔT = 12 °C. HIU induced crystallization in PB samples, but not in the IE ones. Induction in crystallization with HIU was also observed at ΔT = 6 and 3 °C for IE C18:0 20 and 30% and at ΔT = 9 °C only for the 30% samples. Smaller crystals were obtained in all sonicated samples. Melting profiles showed that HIU induced crystallization of low melting triacylglycerols (TAGs) and promoted co-crystallization of low and high melting TAGs. In general, HIU significantly changed the viscosity, G′, and G″ of the IE 20% samples except at ΔT = 12 °C. While G′ and G″ of IE 30% did not increase significantly, the viscosity increased significantly at ΔT = 9, 6, and 3 °C from 1526 ± 880 to 6818 ± 901 Pa.s at ΔT = 3 °C. The improved physical properties of the sonicated IE can make them good contenders for trans-fatty acids replacers