Residue cross sections of 50^{50}Ti-induced fusion reactions based on the two-step model

$^{50}$Ti-induced fusion reactions to synthesize superheavy elements are studied systematically with the two-step model developed recently, where fusion process is divided into approaching phase and formation phase. Furthermore, the residue cross sections for different neutron evaporation channels are evaluated with the statistical evaporation model. In general, the calculated cross sections are much smaller than that of $^{48}$Ca-induced fusion reactions, but the results are within the detection capability of experimental facilities nowadays. The maximum calculated residue cross section for producing superheavy element $Z=119$ is in the reaction $^{50}$Ti+$^{247}$Bk in $3n$ channels with $\sigma_{\rm res}(3n)=0.043$ pb at $E^{*}$ = 37.0 MeV.Comment: 6 pages, 7 figure

Bayesian model averaging on hydraulic conductivity estimation and groundwater head prediction

Characterization of aquifer heterogeneity is inherently difficult because of the insufficiency of data, the inflexibility of parameterization methods, and non-uniqueness of parameterization methods. Groundwater predictions are greatly affected by multiple interpretations of aquifer properties and the uncertainties of model parameters. This study introduces a Bayesian model averaging (BMA) method along with multiple generalized parameterization (GP) methods to identify hydraulic conductivity and along with multiple simulation models to predict groundwater head and quantify the prediction uncertainty. Two major issues about BMA are discussed. The first problem is with using Occam’s window in usual BMA applications. Occam’s window only accepts models in a very narrow range, tending to single out the best method and discard other good methods. A variance window is proposed to replace Occam’s window to cope with this problem. The second problem is with using the Kashyap information criterion (KIC) in the approximation of posterior model probabilities, which tends to prefer highly uncertain model by considering the Fisher information matrix. The Bayesian information criterion (BIC) is recommended because it is able to avoid controversial results and it is computationally efficient. Numerical examples are designed to test the Bayesian model averaging method on hydraulic conductivity identification and groundwater head prediction. The proposed methodologies are then applied to the hydraulic conductivity identification of the Alamitos Gap area, and the hydraulic conductivity estimation and groundwater head prediction of the “1,500-foot” sand in East Baton Rouge Parish, Louisiana. The results show that the GP method provides great flexibility in parameterization with small conditional variance. The use of the variance window is necessary to avoid a dominant model when many models perform equally well. Compared to KIC, BIC is able to give an unbiased posterior model probability. It is also concluded that the uncertainty increases by including multiple models under the BMA framework, but risks are reduced by avoiding overconfidence in the solution from one model

Trojan Horse nanotheranostics with dual transformability and multifunctionality for highly effective cancer treatment.

Nanotheranostics with integrated diagnostic and therapeutic functions show exciting potentials towards precision nanomedicine. However, targeted delivery of nanotheranostics is hindered by several biological barriers. Here, we report the development of a dual size/charge- transformable, Trojan-Horse nanoparticle (pPhD NP) for delivery of ultra-small, full active pharmaceutical ingredients (API) nanotheranostics with integrated dual-modal imaging and trimodal therapeutic functions. pPhD NPs exhibit ideal size and charge for drug transportation. In tumour microenvironment, pPhD NPs responsively transform to full API nanotheranostics with ultra-small size and higher surface charge, which dramatically facilitate the tumour penetration and cell internalisation. pPhD NPs enable visualisation of biodistribution by near-infrared fluorescence imaging, tumour accumulation and therapeutic effect by magnetic resonance imaging. Moreover, the synergistic photothermal-, photodynamic- and chemo-therapies achieve a 100% complete cure rate on both subcutaneous and orthotopic oral cancer models. This nanoplatform with powerful delivery efficiency and versatile theranostic functions shows enormous potentials to improve cancer treatment

Mechanical strain can switch the sign of quantum capacitance from positive to negative

Quantum capacitance is a fundamental quantity that can directly reveal many interactions among electrons and is expected to play a critical role in nanoelectronics. One of many tantalizing recent physical revelations about quantum capacitance is that it can posses a negative value, hence allowing for the possibility of enhancing the overall capacitance in some particular material systems beyond the scaling predicted by classical electrostatics. Using detailed quantum mechanical simulations, we find an intriguing result that mechanical strains can tune both signs and values of quantum capacitance. We use a small coaxially-gated carbon nanotube as a paradigmatical capacitor system and show that, for the range of mechanical strain considered, quantum capacitance can be adjusted from very large positive to very large negative values (in the order of plus/minus hundreds of at-to farads), compared with the corresponding classical geometric value (0.31035 aF). We elucidate the mechanisms underpinning the switching of the sign of quantum capacitance due to strain. This finding opens novel avenues in designing quantum capacitance for applications in nanosensors, energy storage, and nanoelectronics

Cognitive analysis of students' errors and misconceptions in variables, equations, and functions

The fundamental goal of this study is to explore why so many students have difficulty learning mathematics. To achieve this goal, this study focuses on why so many students keep making the same errors over a long period of time. To explore such issues, three basic algebra concepts - variable, equation, and function – are used to analyze students’ errors, possible buggy algorithms, and the conceptual basis of these errors: misconceptions. Through the research on these three basic concepts, it is expected that a more general principle of understanding and the corresponding learning difficulties can be illustrated by the case studies. Although students’ errors varied to a great extent, certain types of errors related to students’ misconceptions occurred frequently and repeatedly after one year of additional instruction. Thus, it is possible to identify students’ misconceptions through working on students’ systematic errors. The causes of students’ robust misconceptions were explored by comparing high-achieving and low-achieving students’ understanding of these three concepts at the object (structural) or process (operational) levels. In addition, high achieving students were found to prefer using object (structural) thinking to solve problems even if the problems could be solved through both algebra and arithmetic approaches. It was also found that the relationship between students’ misconception and object-process thinking explained why some misconceptions were particularly difficult to change. Students’ understanding of concepts at either of two stages (process and object) interacted with either of two aspects (correct conception and misconception). When students had understood a concept as a process with misconception, such misconception was particularly hard to change. In addition, other concerns, such as rethinking the misconception of the “equal sign,” the influence of prior experience on students’ learning, misconceptions and recycling curriculum, and developing teachers’ initial subject knowledge were also discussed. The findings of this study demonstrated that the fundamental reason of misconception of “equal sign” was the misunderstanding of either side of equation as a process rather than as an object. Due to the existence of robust misconceptions as stated in this study, the use of recycling curriculum may have negative effect on students’ understanding of mathematics