Temperature and concentration dependence of liquid phase diffusion coefficients

A study of experimental techniques for the determination of diffusion coefficients for binary mixtures and a study of the existing relationships for these coefficients were carried out. A new three-compartment diffusion cell was developed capable of measuring diffusion coefficients at temperatures up to the normal boiling point (24). By means of this cell, diffusion coefficients were measured for the systems ethanol-water, acetone-water and acetone- chloroform for a range of temperatures up to the normal boiling points. Thus diffusion coefficients for the above mixtures including those at boiling points and at infinite dilution are presented. A relationship was developed to relate diffusion coefficients with temperature and concentration (equation 3-1.21) in binary systems. It agrees better with the experimental data for the associated systems than some literature correlations. By application of parachors a new equation (3-2.4) was developed for the prediction of diffusion coefficients at infinite dilution , (201). This equation, because of the ease of calculating parachors, is more convenient to use than other equations based on the Stokes-Einstein equation. An additive method for the prediction of self-diffusion coefficients was introduced and a correlating equation (3-3.4) was developed. The bond and structural contributions to the constant of the equation were calculated on the basis of a limited amount of experimental data. Despite this the correlation gives reasonable predictions for the temperature range between melting point and boiling point. Another correlation for the prediction of self-diffusion coefficients was developed (203) (equation 3-3.6) by modifying an existing equation. This was possible by applying the relationship between the molal volume at the boiling point and the critical molal volume developed in this work (202). The new equation is more convenient to use. The correlating property of the critical temperature was used to devise a relationship between diffusion coefficients, critical temperature and the working temperature. The two correlating equations (3-4.6) and (3-4.7) can predict diffusion coefficients at various temperatures if one value of the diffusion coefficient at a single temperature is known

Complex Scaled Spectrum Completeness for Coupled Channels

The Complex Scaling Method (CSM) provides scattering wave functions which regularize resonances and suggest a resolution of the identity in terms of such resonances, completed by the bound states and a smoothed continuum. But, in the case of inelastic scattering with many channels, the existence of such a resolution under complex scaling is still debated. Taking advantage of results obtained earlier for the two channel case, this paper proposes a representation in which the convergence of a resolution of the identity can be more easily tested. The representation is valid for any finite number of coupled channels for inelastic scattering without rearrangement.Comment: Latex file, 13 pages, 4 eps-figure

Isoscalar monopole excitations in 16^{16}O: α\alpha-cluster states at low energy and mean-field-type states at higher energy

Isoscalar monopole strength function in $^{16}$O up to $E_{x}\simeq40$ MeV is discussed. We found that the fine structures at the low energy region up to $E_{x} \simeq 16$ MeV in the experimental monopole strength function obtained by the $^{16}$O$(\alpha,\alpha^{\prime})$ reaction can be rather satisfactorily reproduced within the framework of the $4\alpha$ cluster model, while the gross three bump structures observed at the higher energy region ($16 \lesssim E_{x} \lesssim 40$ MeV) look likely to be approximately reconciled by the mean-field calculations such as RPA and QRPA. In this paper, it is emphasized that two different types of monopole excitations exist in $^{16}$O; one is the monopole excitation to cluster states which is dominant in the lower energy part ($E_{x} \lesssim 16$ MeV), and the other is the monopole excitation of the mean-field type such as one-particle one-hole ($1p1h$) which {is attributed} mainly to the higher energy part ($16 \lesssim E_{x} \lesssim 40$ MeV). It is found that this character of the monopole excitations originates from the fact that the ground state of $^{16}$O with the dominant doubly closed shell structure has a duality of the mean-field-type {as well as} $\alpha$-clustering {character}. This dual nature of the ground state seems to be a common feature in light nuclei.Comment: 35 pages, 5 figure

Role of the tensor interaction in He isotopes with a tensor-optimized shell model

We studied the role of the tensor interaction in He isotopes systematically on the basis of the tensor-optimized shell model (TOSM). We use a bare nucleon-nucleon interaction AV8 obtained from nucleon-nucleon scattering data. The short-range correlation is treated in the unitary correlation operator method (UCOM). Using the TOSM+UCOM approach, we investigate the role of tensor interaction on each spectrum in He isotopes. It is found that the tensor interaction enhances the LS splitting energy observed in 5He, in which the p1/2 and p3/2 orbits play different roles on the tensor correlation. In {6,7,8}He, the low-lying states containing extra neutrons in the p3/2 orbit gain the tensor contribution. On the other hand, the excited states containing extra neutrons in the p1/2 orbit lose the tensor contribution due to the Pauli-blocking effect with the 2p2h states in the 4He core configuration.Comment: 11 pages, 8 figure

Comprehensive application of a coupled-channel complex scaling method to the KbarN-piY system

We have applied the coupled-channel complex scaling method (ccCSM) to K^{bar}N-\pi Y system. One advantage of ccCSM is that resonant states as well as scattering states can be treated in the same framework. For the interactions in the system, we have constructed a meson-baryon potential-matrix by basing on the chiral SU(3) theory and respecting the K^{bar}N scattering length obtained in the Martin's analysis. For future purpose to apply it more complicated system such as K^{bar}NN, we adopt a local Gaussian form in the r-space. We have investigated both the non-relativistic (NR) and the semi-relativistic (SR) kinematics. In the SR case, two types of the potentials are obtained. To test the constructed potentials, we have calculated scattering amplitudes and searched resonances. One resonance pole, corresponding to \Lambda(1405), is found in isospin I=0 system around (1419, -20) MeV ((1425, -25) or (1419, -13) MeV) on complex-energy plane with the NR (SR) kinematics. Mean distance between meson and baryon in the resonant state is 1.3 - i0.3 fm (1.2 - i0.5 fm) for NR (SR), in which the states are treated as Gamow states. In addition, we have observed a signature of another pole in lower-energy region involving large decay width, although they are unstable against the change of scaling angle \theta. This may correspond to the lower pole of the double-pole of \Lambda(1405) discussed in literature to date.Comment: 51 pages, 17 figures, to appear in Nuclear Physics

Market surveys and social media provide confirmation of the endangered giant freshwater whipray Urogymnus polylepis in Myanmar

The giant freshwater whipray Urogymnus polylepis is a threatened species that is vulnerable to riverine and coastal marine pressures. Despite its threatened status, the range of U. polylepis is still being determined. In this study, photographic evidence of U. polylepis in Myanmar was provided through market surveys (2017-2018) and social media (Sharks and Rays of Rakhine Facebook page, 2021). Urogymnus polylepis is exposed to fisheries and habitat degradation pressures in Myanmar; therefore, conservation management is likely needed to ensure populations persist into the future

Bioactive phytochemical constituents of wild edible mushrooms from Southeast Asia

Mushrooms have a long history of uses for their medicinal and nutritional properties. They have been consumed by people for thousands of years. Edible mushrooms are collected in the wild or cultivated worldwide. Recently, mushroom extracts and their secondary metabolites have acquired considerable attention due to their biological effects, which include antioxidant, antimicrobial, anti-cancer, anti-inflammatory, anti-obesity, and immunomodulatory activities. Thus, in addition to phytochemists, nutritionists and consumers are now deeply interested in the phytochemical constituents of mushrooms, which provide beneficial effects to humans in terms of health promotion and reduction of disease-related risks. In recent years, scientific reports on the nutritional, phytochemical and pharmacological properties of mushroom have been overwhelming. However, the bioactive compounds and biological properties of wild edible mushrooms growing in Southeast Asian countries have been rarely described. In this review, the bioactive compounds isolated from 25 selected wild edible mushrooms growing in Southeast Asia have been reviewed, together with their biological activities. Phytoconstituents with antioxidant and antimicrobial activities have been highlighted. Several evidences indicate that mushrooms are good sources for natural antioxidants and antimicrobial agent

Analysis of the Caenorhabditis elegans innate immune response to Coxiella burnetii

The nematode Caenorhabditis elegans is well established as a system for characterization and discovery of molecular mechanisms mediating microbe-specific inducible innate immune responses to human pathogens. Coxiella burnetii is an obligate intracellular bacterium that causes a flu-like syndrome in humans (Q fever), as well as abortions in domesticated livestock, worldwide. Initially, when wild type C. elegans (N2 strain) was exposed to mCherry-expressing C. burnetii (CCB) a number of overt pathological manifestations resulted, including intestinal distension, deformed anal region and a decreased lifespan. However, nematodes fed autoclave-killed CCB did not exhibit these symptoms. Although vertebrates detect C. burnetii via TLRs, pathologies in tol-1(-) mutant nematodes were indistinguishable from N2, and indicate nematodes do not employ this orthologue for detection of C. burnetii. sek-1(-) MAP kinase mutant nematodes succumbed to infection faster, suggesting that this signaling pathway plays a role in immune activation, as previously shown for orthologues in vertebrates during a C. burnetii infection. C. elegans daf-2(-) mutants are hyper-immune and exhibited significantly reduced pathological consequences during challenge. Collectively, these results demonstrate the utility of C. elegans for studying the innate immune response against C. burnetii and could lead to discovery of novel methods for prevention and treatment of disease in humans and livestock