HIGH-FREQUENCY VIBRATIONS OF CORRUGATED CYLINDRICAL PIEZOELECTRIC SHELLS

Coupled extensional and flexural cylindrical vibrations of a corrugated cylindrical piezoelectric shell consisting of multiple pieces of circular cylindrical surfaces smoothly connected along their generatrix are studied. To validate the results for the case of relatively thick shells or equivalently high-frequency modes with short wavelengths, existing analysis is extended by considering shear deformation and rotatory inertia. An analytical solution is obtained. Based on the solution, resonant frequencies and mode shapes are calculated.

磷化锡/氮掺杂碳复合材料的简单制备及储锂性能研究——推荐一个综合化学实验

通过磷化锡/氮掺杂碳复合材料的制备、表征及储锂性能测试,帮助学生理解基础化学知识之间的联系,强化实验技能,提升学生的创新思维和综合能力。此外,本实验的开展还可以帮助学生了解储能领域的科技前沿,激发学生的科研兴趣,培养科研能力。因此,建议将本实验纳入化学及应用化学专业高年级本科生的综合化学实验课程。

Ex vivo cartilage explant model for the evaluation of chondrocyte-targeted exosomes

There is no efficient tracking system available for the therapeutic molecules delivered to cartilage.The dense matrix covering the cartilage surface is the main biological barrier that the therapeutic molecules must overcome.In this study,we aimed to establish a system that can dynamically and effectively track the therapeutic molecules delivered to cartilage.To this aim,we adopted bovine and human cartilage explants as ex vivo models for chondrocyte-targeted exosome dispersion.The efficiency of drug delivery was evaluated using frozen sections.The results of this study showed that the penetration and distribution of chondrocyte-targeted exosomes in cartilage explants can be tracked dynamically.Thus,ex vivo cartilage explants provide an effective and economic system to evaluate therapeutic drugs encapsulated in chondrocyte-targeted exosomes in preclinical studies.

Mechanisms of ultraviolet disinfection and chlorination of Escherichia coli： Culturability, membrane permeability,metabolism, and genetic damage

Traditional culture methods may underestimate the tolerance of microorganisms to disinfectants because of the existence of viable but nonculturable or sublethally injured cells after disinfection.The selection of a strict method is crucial for the evaluation of disinfection performance.The actions of 2 typical disinfectants–ultraviolet（UV）and chlorine–on the fecal indicator Escherichia coli were investigated by the detection of culturability,membrane permeability,metabolic activity,deoxyribonucleic acid（DNA）,and messenger ribonucleic acid（m RNA）.During UV disinfection,the irreversible damages in the cell membrane and cellular adenosine triphosphate（ATP）were negligible at low UV doses（80 m J/cm^2）.However,membrane permeability was damaged at low doses of chlorine（5 mg/L）,leading to leakage of cellular ATP.Our study showed that a slight lesion in DNA was detected even at high doses of UV（400 m J/cm^2）and chlorine（5 mg/L）treatments.The decay of m RNA was more rapid than that of DNA.The degradation level of m RNA depended on the choice of target genes.After exposure to 50 m J/cm^2UV dose or 5 mg/L chlorine for30 min,the DNA damage repair function（Rec A m RNA）was inhibited.The m RNA involved in the DNA damage repair function can be a potential indicator of bacterial viability.

Mn atomic layers under inert covers of graphene and hexagonal boron nitride prepared on Rh（111）

Intercalation of metal atoms into the interface of graphene and its supporting substrate has become an intriguing topic for the sake of weakening the interface coupling and constructing metal atomic layers under inert covers. However, this novel behavior has rarely been reported on the analogous hexagonal boron nitride （h-BN） synthesized on metal substrates. Here, we describe a comparative study of Mn intercalation into the interfaces of graphene/Rh（111） and h-BN/Rh（111）, by using atomically-resolved scanning tunneling microscopy （STM） and density functional theory （DFT） calculations. The intercalation was performed by annealing as-deposited Mn clusters, and the starting temperature of Mn intercalation into h-BN/Rh（111） was found to be ~80 ~C higher than that for graphene/Rh（111）. Moreover, the intercalated islands of h-BN/Mn/Rh（111） usually possess more irregular shapes than those of graphene/Mn/Rh（111）, as illustrated by temperature-dependent STM observations. All these experimental facts suggest a stronger interaction of Mn with h-BN/Rh（111） than that with graphene/Rh（111）.

Signature of the hydrogen-bonded environment of liquid water in X-ray emission spectra from first-principles calculations

Based on ab initio molecular dynamics simulations and density functional theory, we performed a systematic theoretical study to elucidate the correlation between the H-bonded environment and X- ray emission spectra of liquid water. The spectra generated from excited water molecules embedded in an intact H-bonded environment yield broader spectral peaks and a larger spectral range than the spectra generated from water molecules in a broken H-bonded environment. Such differences are caused by the local electronic structures on the excited water molecules within the core-hole lifetime that evolve differently through the rearrangement of neighboring water molecules in different H-bonded environments.

Widely tunable optical properties via oxygen manipulation in an amorphous alloy

The ability to widely tune the optical properties of amorphous alloys is highly desirable especially for their potential applications in optoelectronic devices.In this work,we demonstrate that introducing oxygen into an amorphous alloy system of Co-Fe-Ta-B enables the formation of various amorphous derivatives ranging from metals to semiconductors,and eventually to insulators.These oxygencontaining amorphous derivatives gradually become transparent with the opened bandgaps,leading to a continuous increase in their optical transmittance.Furthermore,the reflective metal-type amorphous alloy and transparent insulator-type amorphous oxide of the system can be integrated together to realize the full-color tuning over the entire visible spectral range.This provides a new way to develop large-area color coatings with high design flexibility and full-color tunability.We envisage that the design concept proposed in this work is also applicable to many other amorphous alloy systems,from which all types of amorphous materials including alloys,semiconductors and insulators may be developed to show unprecedented optical functionalities.

Preface to the special topic: New advances in water and water systems

Water and related systems play a central role in science and technology.Although water has unusual and anomalous behaviors,if compared with normal liquids,it is of fundamental interest in many research fields going from chemical-physics to life sciences.The first and well known example of these anomalies is the density maximum,at 277 K,intuited by Galilei[1]in 1612 and lately discovered in Florence[2].

Torsional wave in a circular micro-tube with clogging attached to the inner surface

In the present paper, we study the torsional wave propagation along a micro-tube with clog- ging attached to its inner surface. The clogging accumulated on the inner surface of the tube is modeled as an ＂elastic membrane＂ which is described by the so-called surface elasticity. A power-series solution is particularly developed for the lowest order of wave propagation. The dispersion diagram of the lowest-order wave is numerically presented with the surface （clogging） effect.