Mass Suppression in Octet Baryon Production

There is a striking suppression of the cross section for production of octet baryons in $e^+ e ^-$ annihilation, as the mass of the produced hadron increases. We present a simple parametrization for the fragmentation functions into octet baryons guided by two input models: the SU(3) flavor symmetry part is given by a quark-diquark model, and the baryon mass suppression part is inspired by the string model. We need only eight free parameters to describe the fragmentation functions for all octet baryons. These free parameters are determined by a fit to the experimental data of octet baryon production in $e^+ e ^-$ annihilation. Then we apply the obtained fragmentation functions to predict the cross section of the octet baryon production in charged lepton DIS and find consistency with the available experimental data. Furthermore, baryon production in $pp$ collisions is suggested to be an ideal domain to check the predicted mass suppression.Comment: 20 pages, 5 figure

Degradación de algunos compuestos volátiles de aceites de onagra bajo un proceso UV/TiO2

Off-flavor is one of the limiting factors in the quality and commercial acceptability of evening primrose oil (EPO). The results of this study demonstrated that ultraviolet light irradiated with titanium dioxide (UV/TiO2) was able to effectively reduce odorous aldehyde concentrations, which would produce undesired flavors. Specifically, reductions in the E-2-Decenal, 1-octen-3-ol and hexanoic acid in EPO reached 50, 75.2 and 61.4% after a UV/TiO2 process of 5 min, respectively. The odor active values (OAV) and hierarchical cluster analysis (HCA) showed that the result of the 5 min group was similar to that of the original oil. In addition, the physicochemical characteristics of EPO after processing did not change significantly. The result of the aroma profile analysis was consistent with the OAV and HCA results. Therefore, it has been concluded that 5 min UV/TiO2 treatment could degrade some volatile compounds and provide a potential deodorization method for industry.El mal sabor es uno de los factores limitantes de la calidad y aceptabilidad comercial del aceite de onagra (EPO). Los resultados de este estudio demostraron que la luz ultravioleta irradiada con dióxido de titanio (UV/TiO2) fue capaz de reducir eficazmente las concentraciones de aldehídos volátiles, que darían olores no deseados. En concreto, la reducción del E-2-Decenal, 1-octen-3-ol y el ácido hexanoico en EPO alcanzó el 50%, 75,2% y 61,4% respectivamente tras un proceso UV/TiO2 de 5 min. Los valores de olor activo (OAV) y el análisis de conglomerados jerárquicos (HCA) mostraron que el resultado del grupo de 5 min fue similar al del aceite original. Además, las características fisicoquímicas del EPO después del procesamiento no cambiaron significativamente. El resultado del análisis del perfil de aroma fue consistente con nuestro resultado de OAV y HCA. Por lo tanto, se ha llegado a la conclusión de que el tratamiento con UV/TiO2 durante 5 min podría degradar algunos compuestos volátiles y proporcionar un método de desodorización potencial para la industria

Revisión sobre métodos de preparación, mecanismos y aplicaciones de péptidos antioxidantes en aceites

Natural antioxidants, especially those used in edible oil, are safer compared to chemically synthesized antioxidants. Therefore, research on natural antioxidants has become prevelant. Antioxidant peptides derived from food protein can effectively prevent oil oxidation. Protein hydrolyzation is widely applied for the production of antioxidant peptides in industry, and bioinformatics is employed nowadays to generate the desired peptide sequence. Furthermore, the mechanism of antioxidant peptides in the oil system is still controversial, which limits the further development of antioxidant peptides as food antioxidants. This review introduces the preparation method of antioxidant peptides and their mechanisms as well as applications in the oil. It will help to comprehensively understand the function of antioxidant peptides and promote their development in the oil field.Los antioxidantes naturales, especialmente utilizados en aceites comestibles, son más seguros en comparación con los antioxidantes sintetizados químicamente. Por lo tanto, la investigación sobre antioxidantes naturales se convierte en un punto de interés. Los péptidos antioxidantes derivados de las proteínas alimentarias pueden prevenir eficazmente la oxidación del aceite. La hidrolización de proteínas se usa ampliamente en la industria para la producción de péptidos antioxidantes y la bioinformática se emplea hoy en día para generar la secuencia de péptidos deseada. Además, el mecanismo de los péptidos antioxidantes en el sistema oleoso sigue siendo controvertido, lo que limita el desarrollo posterior de péptidos antioxidantes como antioxidantes alimentarios. Esta revisión presenta el método de preparación de péptidos antioxidantes y su mecanismo, así como las aplicaciones en aceite, lo que ayudará a comprender de manera integral la función de los péptidos antioxidantes y promoverá su desarrollo en el campo petrolero

Short Fatigue Crack Growth at Different Maintenance Times for LZ50 Steel

Based on the average fatigue life of LZ50 axle steel specimens without surface rolling, five maintenance times were determined. Accordingly, five groups of specimens were turned and rolled at above maintenance times and were fatigued using a replica technique. The results show that the crack growth rate is much lower than that before rolling at a given dominant short crack size. The effective short crack density of all specimens decreases significantly after maintenance. However, with the postponement of surface maintenance, the highest effective short crack density for the five studied groups of specimens increases continuously, while the average fatigue life decreases gradually. A maintenance time effect function is presented to refine a short crack growth model described previously. The revifined model can include a significant effect of the maintenance time on short crack growth and predict its patterns at different maintenance times with exiting test results for LZ50 axle steel.На основании средней усталостной долговечности образцов осевой стали LZ50, не подвергавшихся поверхностной обкатке роликами, были определены пять модельных межремонтных циклов. Соответственно пять групп образцов были обточены и обкатаны роликами при вышеуказанных межремонтных циклах и подвергнуты испытанию на усталость по методу реплик. Результаты показывают, что скорость роста трещин гораздо ниже таковой до обкатки роликами при заданном преобладающем размере коротких трещин. Эффективная плотность коротких трещин для всех образцов значительно уменьшается после обработки. Однако если поверхностную обработку вовремя не выполняют, наибольшая эффективная плотность коротких трещин для пяти исследуемых групп образцов непрерывно возрастает, тогда как средняя усталостная долговечность постепенно снижается. Приведена функция, описывающая эффект межремонтных циклов, для уточнения предложенной ранее модели роста коротких трещин. Уточненная модель может учитывать существенное влияние межремонтного цикла на рост коротких трещин и прогнозировать характер их роста при различных межремонтных циклах на основании полученных результатов испытаний осевой стали LZ50

A Probabilistic Model for Describing Short Fatigue Crack Growth Behavior of LZ50 Steel

Fatigue damage process of metal components and structures with smooth surface belongs primarily to stage of short fatigue crack. To characterize the random growth behavior of short fatigue crack and to apply the crack growth rate model for engineering safety assessment, a probabilistic model is proposed with consideration of the test data scattering regularity. This probabilistic model is based on the multi-microstructural barriers model and can describe the deceleration behavior of growth rate during the whole short fatigue crack propagation process. To take the statistical characteristics of whole test data into account, the idea from the general maximum likelihood method which is widely used in parameters estimation of fatigue S-N curves and ε-N curves is inherited. While estimating the parameters of the probabilistic model, conventional correlation coefficient optimization method is extended for calculating the parameters of both the mean curve and the standard deviation curve. Analysis on the test data of LZ50 steel indicates the reasonability and availability of present model

An Improved Projection Method for Determination of Fatigue Parameters of Metal Structures Based on Spherical Direction Cosine Group Construction

The key components of railway rolling stock are almost constantly in the multiaxial stress state in service. To evaluate the fatigue strength of the structure, stress parameters should be obtained beforehand. The traditional projection method assumes that the maximum principal stress is the maximum tensile stress, and then the projection process is performed without taking the tension/ compression states of principal stresses into account. To address these inadequacies, a method for fatigue parameter determination was proposed based on principal stress projection toward a spherical direction cosine group. This method can determine the direction of maximum tensile stress and preserve the tension/compression attribute of stress during calculating the maximum stress and the minimum stress. Therefore, the physical meaning of present improved method is more apparent than the traditional projection method, and its algorithm is simple and effective. The fatigue strength assessments of a welded bogie frame were performed utilizing the traditional projection method and present method respectively. Results show that some maximum stresses calculated by the improved method could be 19.4% higher than those obtained by the traditional one at some nodes, while the minimum stresses and the stress ratio deduced from these two methods could even be of opposite sign. The present method, which takes the tension/compression properties of principal stresses into consideration, is more reasonable, as compared with the traditional projection method, and thus the fatigue strength assessment results are more credible

Nonlinear current-induced forces in Si atomic wires

We report first-principles calculations of current-induced forces in Si atomic wires as a function of bias and wire length. We find that these forces are strongly nonlinear as a function of bias due to the competition between the force originating from the scattering states and the force due to bound states. We also find that the average force in the wire is larger the shorter the wire, suggesting that atomic wires are more difficult to break under current flow with increasing length. The last finding is in agreement with recent experimental data.Comment: 4 figure

Charmonium states in QCD-inspired quark potential model using Gaussian expansion method

We investigate the mass spectrum and electromagnetic processes of charmonium system with the nonperturbative treatment for the spin-dependent potentials, comparing the pure scalar and scalar-vector mixing linear confining potentials. It is revealed that the scalar-vector mixing confinement would be important for reproducing the mass spectrum and decay widths, and therein the vector component is predicted to be around 22%. With the state wave functions obtained via the full-potential Hamiltonian, the long-standing discrepancy in M1 radiative transitions of $J/\psi$ and $\psi^{\prime}$ are alleviated spontaneously. This work also intends to provide an inspection and suggestion for the possible $c\bar{c}$ among the copious higher charmonium-like states. Particularly, the newly observed X(4160) and X(4350) are found in the charmonium family mass spectrum as $M(2^1D_2)= 4164.9$ MeV and $M(3^3P_2)= 4352.4$ MeV, which strongly favor the $J^{PC}=2^{-+}, 2^{++}$ assignments respectively. The corresponding radiative transitions, leptonic and two-photon decay widths have been also predicted theoretically for the further experimental search.Comment: 16 pages,3 figure

Evidence for SU(3) symmetry breaking from hyperon production

We examine the SU(3) symmetry breaking in hyperon semileptonic decays (HSD) by considering two typical sets of quark contributions to the spin content of the octet baryons: Set-1 with SU(3) flavor symmetry and Set-2 with SU(3) flavor symmetry breaking in HSD. The quark distributions of the octet baryons are calculated with a successful statistical model. Using an approximate relation between the quark fragmentation functions and the quark distributions, we predict polarizations of the octet baryons produced in $e^+e^-$ annihilation and semi-inclusive deeply lepton-nucleon scattering in order to reveal the SU(3) symmetry breaking effect on the spin structure of the octet baryons. We find that the SU(3) symmetry breaking significantly affects the hyperon polarization. The available experimental data on the $\Lambda$ polarization seem to favor the theoretical predictions with SU(3) symmetry breaking. We conclude that there is a possibility to get a collateral evidence for SU(3) symmetry breaking from hyperon production. The theoretical errors for our predictions are discussed.Comment: 3 tables, 14 figure

Market segmentation and ideal point identification for new product design using fuzzy data compression and fuzzy clustering methods

In product design, various methodologies have been proposed for market segmentation, which group consumers with similar customer requirements into clusters. Central points on market segments are always used as ideal points of customer requirements for product design, which reflects particular competitive strategies to effectively reach all consumers’ interests. However, existing methodologies ignore the fuzziness on consumers’ customer requirements. In this paper, a new methodology is proposed to perform market segmentation based on consumers’ customer requirements, which exist fuzziness. The methodology is an integration of a fuzzy compression technique for multi-dimension reduction and a fuzzy clustering technique. It first compresses the fuzzy data regarding customer requirements from high dimensions into two dimensions. After the fuzzy data is clustered into marketing segments, the centre points of market segments are used as ideal points for new product development. The effectiveness of the proposed methodology in market segmentation and identification of the ideal points for new product design is demonstrated using a case study of new digital camera design