3,912 research outputs found
Theoretical study of the synthesis of superheavy nuclei with Z= 119 and 120 in heavy-ion reactions with trans-uranium targets
By using a newly developed di-nuclear system model with a dynamical potential
energy surface---the DNS-DyPES model, hot fusion reactions for synthesizing
superheavy nuclei (SHN) with the charge number Z = 112-120 are studied. The
calculated evaporation residue cross sections are in good agreement with
available data. In the reaction 50Ti+249Bk -> (299-x)119 + xn, the maximal
evaporation residue (ER) cross section is found to be about 0.11 pb for the
4n-emission channel. For projectile-target combinations producing SHN with
Z=120, the ER cross section increases with the mass asymmetry in the incident
channel increasing. The maximal ER cross sections for 58Fe+244Pu and 54Cr +
248Cm are relatively small (less than 0.01 pb) and those for 50Ti+249Cf and
50Ti+251Cf are about 0.05 and 0.25 pb, respectively.Comment: 6 pages, 5 figures; Phys. Rev. C, in pres
Local regularization assisted split augmented Lagrangian shrinkage algorithm for feature selection in condition monitoring
\ua9 2024 The Author(s)Feature selection plays a vital role in improving the efficiency and accuracy of condition monitoring by constructing sparse but effective models. In this study, an advanced feature selection algorithm named the local regularization assisted split augmented Lagrangian shrinkage algorithm (LR-SALSA) is proposed. The feature selection is realized by solving a l1-norm optimization problem, which usually selects more sparse and representative features at less computational costs. The proposed algorithm operates in two stages, namely variable selection and coefficient estimation. In the stage of variable selection, the primal problem is converted into three subproblems which can be solved separately. Then individual penalty parameters are applied to every coefficient of the model when dealing with the first subproblem. Under the Bayesian evidence framework, an iterative algorithm is derived to optimize these hyperparameters. During the optimization process, redundant variables will be pruned to guarantee model sparsity and improve computational efficiency at the same time. In the second stage, the coefficients for the selected model terms are determined using the least squares technique. The superior performance and efficiency of the proposed LR-SALSA method are validated through two numerical examples and a real-world cutting tool wear prediction case study. Compared with the existing methods, the proposed method can generate a sparse model and ensure a good trade-off between estimation accuracy and computational efficiency
Proper Matter Collineations of Plane Symmetric Spacetimes
We investigate matter collineations of plane symmetric spacetimes when the
energy-momentum tensor is degenerate. There exists three interesting cases
where the group of matter collineations is finite-dimensional. The matter
collineations in these cases are either four, six or ten in which four are
isometries and the rest are proper.Comment: 10 pages, LaTex, accepted for publication in Modern Physics Letters
Load Analysis of pitch bearing considering non-quenching zone
The pitch bearing of the MW-class wind turbine has a weak zone which is not quenched. In the complicated service environment of the wind turbine, the pitch bearing often has breakage accidents in the non-quenching zone. Firstly, this paper takes the pitch bearing as the object and establishes the pitch bearing model with weak zone. Subsequently, the load variation law of the pitch bearing considering non-quenching is analyzed in the four extreme conditions. Finally, the feasibility of the model is proved by comparing the simulation data with the data obtained from the theoretical formula
Quantitative Methods in System-Based Drug Discovery
Modern pharmaceutical industries have faced significant challenges to deliver safe and effective medicines because of significant toxicity and severe side effects of discovered drugs. On the other hand, recent developments and advances in system-based pharmacology aim to address these challenges. In this chapter, we provide an overview of quantitative methods for system-based drug discovery. System-based drug discovery integrates chemical, molecular, and systematic information and applies this knowledge to the designing of small molecules with controlled toxicity and minimized side effects. First, we discuss current approaches for drug discovery and outline their advantages and disadvantages. Next, we introduce basic concepts of systems pharmacology with an emphasis on ligand-based drug discovery and target identification. This is followed by a discussion on structure-based drug design and statistical tools for pharmaceutical research. Finally, we provide an overview of future directions in systems pharmacology that will guide further developments
Computer-Aided Biosensor Design
Amperometric biosensors are widely used in point-of-care medical devices that help patients control blood glucose and cholesterol levels in an effective and convenient way. On the other hand, computer-aided technologies for biosensor design remain an actively developing field. In this chapter, we present a computational model for biosensor design that uses a reaction-diffusion equation. We have successfully applied this model to simulate cholesterol analysis based on a multienzyme system. Furthermore, we show that this computer-aided approach can be used to optimize biosensor performance. This model can be applied to industry-grade biosensor development and can be easily extended to model multiple types of biosensors for a wide array of clinical applications
Unified nonequilibrium dynamical theory for exchange bias and training effects
We investigate the exchange bias and training effects in the FM/AF
heterostructures using a unified Monte Carlo dynamical approach. This real
dynamical method has been proved reliable and effective in simulating dynamical
magnetization of nanoscale magnetic systems. The magnetization of the
uncompensated AF layer is still open after the first field cycling is finished.
Our simulated results show obvious shift of hysteresis loops (exchange bias)
and cycling dependence of exchange bias (training effect) when the temperature
is below 45 K. The exchange bias fields decrease with decreasing the cooling
rate or increasing the temperature and the number of the field cycling. With
the simulations, we show the exchange bias can be manipulated by controlling
the cooling rate, the distributive width of the anisotropy energy, or the
magnetic coupling constants. Essentially, these two effects can be explained on
the basis of the microscopical coexistence of both reversible and irreversible
moment reversals of the AF domains. Our simulated results are useful to really
understand the magnetization dynamics of such magnetic heterostructures. This
unified nonequilibrium dynamical method should be applicable to other exchange
bias systems.Comment: Chin. Phys. B, in pres
An efficient system for the production of the medicinally important plant: Asparagus cochinchinensis (Lour.) Merr.
An in vitro cultivation protocol was developed for Asparagus cochinchinensis a species threatened by over collection due to its importance as a medicinal plant in China. Adventitious shoot induction was most successful by using hypocotyls as explants for propagation on Murashige and Skoog (Murashige et al., 1962) medium supplemented with 4.5 μM N6-benzylaminopurine (BA) only as well as with 3.0 μM α- naphthalene acetic acid (NAA) and 4.5 μM BA. For continuous subculture, indole-3-acetic acid (IAA) and BA (μM) at a ratio of 3.0:4.5 or 3.0:9.0 had the best regeneration potential producing approximately four plantlets per nodal explants. Plantlets had 4 – 5 nodes that could be utilized for the following subculture phase to induce axillary shoots. The plantlets were placed on ½-strength MS medium, indole-3-butyric acid (IBA) was included in the media at a concentration of 2.5 or 5.0 M. This propagation regime has the capacity for producing 1000 – 2000 plants from one shoot after 3 months long subculture cycles, making it highly attractive for implementation as an in vitro conservation strategy. The micropropagated plants were easily acclimatized (80%) within a month after rooting in vitro and being planted ex vitro in a sand : soil : peat moss : vermiculite (1:2:1:1; v/v/v/v) mixture.Key words: Medicinal herbs, Asparagus cochinchinensis (Lour.) Merr., micropropagation
Increased papillae growth and enhanced short-chain fatty acid absorption in the rumen of goats are associated with transient increases in cyclin D1 expression after ruminal butyrate infusion
We tested the hypothesis that the proliferative effects of intraruminal
butyrate infusions on the ruminal epithelium are linked to upregulation in
cyclin D1 (CCND1), the cyclin-dependent kinase 4 (CDK4), and their possible
association with enhanced absorption of short-chain fatty acids (SCFA). Goats
(n=23) in 2 experiments (Exp.) were fed 200 g/d concentrate and hay ad
libitum. In Exp. 1, goats received an intraruminal infusion of sodium butyrate
at 0.3 (group B, n=8) or 0 (group C, n=7) g/kg of body weight (BW) per day
before morning feeding for 28 d and were slaughtered 8 h after the butyrate
infusion. In Exp. 2, goats (n=8) received butyrate infusion and feeding as in
Exp. 1. On d 28, epithelial samples were biopsied from the antrium ruminis at
0, 3, and 7 h after the last butyrate infusion. In Exp. 1, the ruminal molar
proportional concentration of butyrate increased in group B by about 110%
after butyrate infusion and remained elevated for 1.5 h; thereafter, it
gradually returned to the baseline (preinfusion) level. In group C, the molar
proportional concentration of butyrate was unchanged over the time points. The
length and width of papillae increased in B compared with C; this was
associated with increased numbers of cells and cell layers in the epithelial
strata and an increase in the surface area of 82%. The mRNA expression of
CCND1 increased transiently at 3 h but returned to the preinfusion level at 7
h following butyrate infusion in Exp. 2. However, it did not differ between B
and C in Exp. 1, in which the ruminal epithelium was sampled at 8 h after
butyrate infusion. The mRNA expression of the monocarboxylate transporter
MCT4, but not MCT1, was stably upregulated in B compared with C. The estimated
absorption rate of total SCFA (%/h) increased in B compared with C. We
conclude that transient increases in cyclin D1 transcription contribute to
butyrate-induced papillae growth and subsequently to the increased absorption
of SCFA in the ruminal epithelium of goats
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