Production of the top-pions at the THERA collider based γp\gamma p collisions

In the framework of the topcolor-assisted technicolor (TC2) models, we study the production of the top-pions $\pi^{0}_{t}$, $\pi_{t}^{\pm}$ via the processes $ep\to\gamma c\to\pi^{0}_{t}c$ and $ep\to\gamma c\to\pi^{\pm}_{t}b$ mediated by the anomalous top coupling $tc\gamma$. We find that the production cross section of the process $ep\to\gamma c\to\pi^{0}_{t}c$ is very small. With reasonable values of the parameters in TC2 models, the production cross section of the process $ep\to\gamma c\to\pi^{\pm}_{t}b$ can reach $1.2pb$. The charged top-pions $\pi^{\pm}_{t}$ might be directly observed via this process at the THERA collider based $\gamma p$ collisions.Comment: 10 pages, 3 figure

Flavor changing Z decay Z→bsˉ(bˉs)Z\to b\bar{s}(\bar{b}s) in topcolor-assisted technicolor models

In the context of topcolor-assisted technicolor (TC2) models, we examine the flavor changing (FC) Z decay $Z\to b\bar{s}(\bar{b}s)$ and calculate the contributions of the new particles predicted by TC2 models to the branching ratio Br($Z\to b\bar{s}+\bar{b}s$). We find that the contributions mainly come from the top-pions. In most of the parameter space, the Br($Z\to b\bar{s}+\bar{b}s$) can reach $10^{-5}$, which may be detected in near future experiments such as Giga-Z version of the TESLA. Thus, the FC Z decay $Z\to b\bar{s}(\bar{b}s)$ can be used to test TC2 models.Comment: Final version to appear in Nucl. Phys. B. References adde

The process e+e−→ννˉγe^{+}e^{-}\to\nu\bar{\nu}\gamma in topcolor-assisted technicolor models

In the context of topcolor-assisted technicolor (TC2) models, we consider the process $e^{+}e^{-}\to \nu\bar{\nu}\gamma$ and calculate the cross section of this process at leading order.It is shown that the extra U(1) gauge boson $Z^{\prime}$ predicted by TC2 models can give significant contributions to the process $e^{+}e^{-}\to \nu_{\tau}\bar{\nu}_{\tau}\gamma$, which may be detected in the future high energy linear $e^{+}e^{-}$ collider(LC) experiments.Comment: latex files,9 pages, 3 figure

Risk Assessments of Plant Leaf and Soil Mercury Pollution in Different Functional Areas of Changchun City

Mercury is a global pollutant that has attracted widespread attention due to its persistence, concealment, and ease of migration. As the main setting for human production and life, urban ecosystems play significant roles in the global mercury cycle. Urban vegetation also plays an important role in regional mercury cycles. In this study, several common tree species in the green vegetation of Changchun were used as research objects to examine the mercury pollution characteristics of leaf litter and the surrounding soil. In this investigation, 100 sampling sites were set up in Changchun City to collect leaf litter and the surrounding topsoil. An RA-915+ Hg analyzer was used to determine the total mercury concentration levels. The results showed that content levels of mercury in plants ranged between 0.0133 and 0.1945 mg/kg, and different species displayed varying levels of mercury accumulation. For example, the content of mercury in Pyrus ussuriensis Maxim. was found to be 0.0755 mg/kg higher than that in the other examined subjects. It was also determined that the plant mercury concentration levels were the highest in the older industrial zones, while the lowest mercury levels were found in the new economic development zones. Furthermore, the plant mercury levels of the roadside areas were higher due to vehicle pollution discharge. Regarding the mercury pollution levels of the surface-layer soil, the soil of old industrial zones’ surface layers had higher levels of mercury pollution than the other tested sites. However, no notable connection was observed between the mercury concentration levels of the vegetation and those of the soil. This study’s results revealed that the mercury pollution of plants in Changchun City is not severe. The mercury levels in the industrial zones were graded as moderate, and those in the other regions were graded as low

multipleaucoresinceo2hollowspheresforthesuperiorcatalyticreductionofpnitrophenol

催化剂的微观结构在催化还原反应、有机物氧化反应及有机物转化反应中起着关键作用.本文利用无模板方法合成了多金核中空二氧化铈微球催化剂.将制备好的二氧化铈中空微球浸渍到一定浓度的氯金酸溶液中,然后多次洗涤除去表面吸附的氯金酸离子,最后通过硼氢化钠还原制成中空氧化铈微球包覆的多金核的核壳结构催化剂.将该核壳结构材料用于硝基苯酚加氢反应与金纳米粒子及氧化铈微球相比,多金核中空二氧化铈核壳结构表现出优越的活性和稳定性.通过这种浸渍洗涤再还原的简单方法合成的多金核二氧化铈催化剂有望应用于生物医药和能源环境等领域

multipleaucoresinceo2hollowspheresforthesuperiorcatalyticreductionofpnitrophenol

催化剂的微观结构在催化还原反应、有机物氧化反应及有机物转化反应中起着关键作用.本文利用无模板方法合成了多金核中空二氧化铈微球催化剂.将制备好的二氧化铈中空微球浸渍到一定浓度的氯金酸溶液中,然后多次洗涤除去表面吸附的氯金酸离子,最后通过硼氢化钠还原制成中空氧化铈微球包覆的多金核的核壳结构催化剂.将该核壳结构材料用于硝基苯酚加氢反应与金纳米粒子及氧化铈微球相比,多金核中空二氧化铈核壳结构表现出优越的活性和稳定性.通过这种浸渍洗涤再还原的简单方法合成的多金核二氧化铈催化剂有望应用于生物医药和能源环境等领域