Enhancing thermoelectric figure-of-merit by low-dimensional electrical transport in phonon-glass crystals

Low-dimensional electronic and glassy phononic transport are two important ingredients of highly-efficient thermoelectric material, from which two branches of the thermoelectric research emerge. One focuses on controlling electronic transport in the low dimension, while the other on multiscale phonon engineering in the bulk. Recent work has benefited much from combining these two approaches, e.g., phonon engineering in low-dimensional materials. Here, we propose to employ the low-dimensional electronic structure in bulk phonon-glass crystal as an alternative way to increase the thermoelectric efficiency. Through first-principles electronic structure calculation and classical molecular dynamics simulation, we show that the $\pi$-$\pi$ stacking Bis-Dithienothiophene molecular crystal is a natural candidate for such an approach. This is determined by the nature of its chemical bonding. Without any optimization of the material parameter, we obtain a maximum room-temperature figure of merit, $ZT$, of $1.48$ at optimal doping, thus validating our idea.Comment: Nano Lett.201

Enhancement of Interfacial Thermal Conductance of SiC by Overlapped Carbon Nanotubes and Intertube Atoms

A new way was proposed to enhance the interfacial thermal conductance (ITC) of silicon carbide (SiC) composite through the overlapped carbon nanotubes (CNTs) and intertube atoms. By nonequilibrium molecular dynamics (NEMD) simulations, the dependence of ITC on both the number of intertube atoms and the temperature was studied. It is indicated that the ITC can be significantly enhanced by adding intertube atoms and finally becomes saturated with the increase of the number of intertube atoms. And the mechanism is discussed by analyzing the probability distributions of atomic forces and vibrational density of states (VDOS). This work may provide some guidance on enhancing the ITC of CNT-based composites

Long wavelength single photon like driven photolysis via triplet triplet annihilation

Photolysis has enabled the occurrence of numerous discoveries in chemistry, drug discovery and biology. However, there is a dearth of efficient long wavelength light mediated photolysis. Here, we report general and efficient long wavelength single photon method for a wide array of photolytic molecules via triplet-triplet annihilation photolysis. This method is versatile and LEGO -like. The light partners (the photosensitizers and the photolytic molecules) can be energetically matched to adapt to an extensive range of electromagnetic spectrum wavelengths and the diversified chemical structures of photoremovable protecting groups, photolabile linkages, as well as a broad array of targeted molecules. Compared to the existing photolysis methods, our strategy of triplet-triplet annihilation photolysis not only exhibits superior reaction yields, but also resolves the photodamage problem, regardless of whether they are single photon or multiple photon associated. Furthermore, the biological promise of this LEGO system was illustrated via developing ambient air-stable nanoparticles capable of triplet-triplet annihilation photolysis

Current address: National Institutes of Health, Bldg. 8, Rm. 111, Be-thesda, MD 20892

ABSTRACT To investigate the influence of dopamine (DA) nerves on haloperidol (HAL)-induced oral dyskinesias, rats were first injected at 3 days after birth with 6-hydroxydopamine HBr (200 g i.c.v., salt form; 6-OHDA) or vehicle, after desipramine HCl (20 mg/kg i.p., 1 hr) pretreatment. Two months later HAL (1.5 mg/kg/day, 2 days a week for 4 weeks, then daily for 10 months) was added to the drinking water of half the rats. Numbers of vacuous chewing movements, recorded in 1-min increments every 10 min for 1 hr, increased from Ͻ5 to about 17 oral movements per session in intact rats, 14 weeks after instituting HAL (P Ͻ .01 vs. intact rats drinking tap water). In HAL-treated 6-OHDA-lesioned rats, oral activity increased to Ͼ30 oral movements per session (P Ͻ .01 vs. HAL-treated intact rats). These levels of oral activity persisted in intact and 6-OHDA-lesioned rats as long as HAL was administered. After 11 months of HAL treatment, but 8 or 9 days after HAL withdrawal, DA was found to be reduced 97%, whereas serotonin was increased 29% in the striatum of 6-OHDA-lesioned rats. In HAL-treated intact and lesioned rats the B max for DA D 2 binding sites was elevated about 70%. With reverse transcription polymerase chain reaction, the mRNA level for DA D 2L but not D 2S receptors was also found to be elevated about 70%. In a fraction of 6-OHDA-lesioned rats that were observed for 8 months after HAL withdrawal, oral activity persisted without decrement and was not accompanied by a change in the B max or mRNA level for DA D 2 receptors. These findings demonstrate that in rats largely DA-denervated as neonates, long-term HAL treatment produces an unusually high number of oral movements that persists for 8 months after HAL withdrawal and is not accompanied by an increase in DA D 2 receptor expression. Tardive dyskinesia, an extrapyramidal syndrome caused by neuroleptics in the treatment of psychiatric disorders, is a disorder for which there is no satisfactory treatment. The prevalence of TD has increased steadily by about 1% per year during the past two decades Cholinergic systems are also known to have a prominent regulatory action on oral activity. Acute systemic treatments with pilocarpine, a muscarinic agonist, or physostigmine, a cholinesterase inhibitor, produce oral activity in rats. The same effect is produced when pilocarpine is injected directly into the ventrolateral striatum. Long-term treatment with physostigmine similarly increases oral activity. These many actions are attenuated by the muscarinic receptor antagonist, scopolamine Bilateral microinfusion of the GABA receptor antagonist bicuculline and GABA-depleting agent isoniazid into the sub