Singlet-triplet transitions in highly correlated nanowire quantum dots

We consider a quantum dot embedded in a three-dimensional nanowire with tunable aspect ratio a. A configuration interaction theory is developed to calculate the energy spectra of the finite 1D quantum dot systems charged with two electrons in the presence of magnetic fields B along the wire axis. Fruitful singlet-triplet transition behaviors are revealed and explained in terms of the competing exchange interaction, correlation interaction, and spin Zeeman energy. In the high aspect ratio regime, the singlet-triplet transitions are shown designable by tuning the parameters a and B. The transitions also manifest the highly correlated nature of long nanowire quantum dots.Comment: 4 pages, 4 figure

Development of Solar-Optical Models for Energy Performance Analysis of Draperies in Complex Fenestration Systems

Window coverings have been used for many years to provide protection from undesired environmental conditions and to regulate indoor conditions. Models for complex fenestration systems (CFS), a term coined in the early 90’s in light of optical and thermal complexity of shading elements, are essential in pursuing multiple objectives of modern building design. This research focuses on energy performance of one type of window shading, draperies. Coupled with a rectangular pleated drape model, the conventional three-property Keyes Universal Chart (KUC) predicts shading effect of pleated drapes. This thesis offers a much improved KUC, the b&C model, which was developed using fabric solar-optical properties obtained by a highly accurate spectrophotometer. The improved KUC has largely eliminated the bias and reduced the uncertainty present in the original KUC. The b&C model, also a three-property KUC, uses manipulative functional relationships. A fourth property, fabric thickness, was explored to better correlate the three-property relationships, resulting in the customized KUC for increased accuracy. Previous pleated drape models comprised only rectangular pleats (i.e., RPD). A triangular pleated drape (TPD) model was built for comparison with RPD. In parallel, an experiment was designed to measure and study the effects of fullness, pleating profile, and angle of incidence for selected fabrics. A comprehensive set of transmittance test results was attained using the Broad Area Illuminating Integrating Sphere (BAI-IS) system. Both RPD and TPD models were assessed with the experiment. Discussions on the effects of variables are offered. The improved/customized KUC combined with a RPD/TPD model can be implemented in building energy simulation software or used as a stand-alone tool to determine the shading effect of a pleated drape on the solar heat gain

Comparative tests on the performance of solar stills enhanced by pebbles, corrugated plate and membrane distillation and construction of performance prediction model for rock type still

To improve the water production capacity of solar still (SS), realize the theoretical prediction of the enhanced SS performance, and enrich the theoretical research basis of the desalination technology of SS, this paper sets up three kinds of enhancement measures, namely, rock, corrugated plate and membrane distillation, tests the enhanced water production effect, and reveals the enhanced operation mechanism. At the same time, a per- formance prediction model of rock enhanced was established based on the body-centered cubic stacking rock technology, and the influence of rock parameters on the distillation effect was studied. The study found that the water production increment of the three enhancement measures was concentrated in the rising period of the water production of the SS, and the total water production was 6.38 %, 12.30 % and 11.63 % higher than that of the traditional basin SS, respectively. The rock or corrugated plate enhances the distillation effect by elevating the seawater temperature and its temperature difference with the cover plate, and the membrane distillation increases the total water production through the additional water production of the membrane. Moreover, the constructed model can effectively predict the characteristics of rock enhanced SS. The increase in the rock layer thickness and the decrease in the rock particle size and material heat capacity both enhance the total daily water production, but the effect of rock particle size and material is weak. Although the increase of thickness increases the water production obviously, it aggravates the fluctuation of water production

Research on operation characteristics of wind supercharged solar chimney dust haze removal street light

To realize distributed dust haze removal in street canyons, an innovative wind supercharged solar chimney dust haze removal street light is proposed. The design couples solar chimney technology with municipal street lighting, utilizing thermal pressure, chimney effect and wind supercharged wheel to power the system, which achieves the dual function of lighting and dust haze removal. Operational testing on a small-scale model showed: the airflow warms up the most in the inlet area, and the model creates updrafts with a dust haze removal effect. The filtration system consists of various filter screens arranged by descending filtration efficiency: HEPA, primary filter cotton, activated carbon and nylon filter screens, with airflow velocity in the flow runner in the opposite order. The average filtration efficiency is positively correlated with the pressure drop and negatively correlated with the overflow airflow. A combination of different material filter screens is more effective than simply increasing the thickness of a single filter screen. A single layer of 10 mm primary filter cotton has the highest total mass flow of clean air, reaching 4.18 g. HEPA has the highest average filtration efficiency at 93.1 %. This innovative approach offers an efficient solution for urban air purification while maintaining street lighting functionality

Experimental research on night heat loss and dust effect of distillation-solar chimney power plant

To more comprehensively grasp the operating characteristics of the solar chimney power plants combined with distillation and provide a valuable reference for the design and operation of the power plants, a comparative test platform was built in this paper, which adopted manual covering of insulation layer and dust, and explored for the first time the impact of the insulation layer and dust accumulation on the operational characteristics of power plants. The results show that the insulation layer can increase the temperature rise of the airflow at night by a maximum of 2.1 ◦C, which is 25.9 %; but at the same time, it will reduce the temperature difference between the seawater and the solar still cover, resulting in a decrease of more than 7 % in daily water yield. Therefore, if the power plant pursues water production, it is not necessary to install insulation layers. Dust accumulation will affect the heat collection and storage performance of the system, reduce the power output, and shorten the effective power generation time; at the same time, lowering the seawater temperature will also reduce the water yield of the system by more than 10 %, so the power plant must regularly clean the collector roof

Proteomic profiling of proteins associated with the rejuvenation of Sequoia sempervirens (D. Don) Endl

Background: Restoration of rooting competence is important for rejuvenation in Sequoia sempervirens (D. Don) Endl and is achieved by repeatedly grafting Sequoia shoots after 16 and 30 years of cultivation in vitro. Results: Mass spectrometry-based proteomic analysis revealed three proteins that differentially accumulated in different rejuvenation stages, including oxygen-evolving enhancer protein 2 (OEE2), glycine-rich RNA-binding protein (RNP), and a thaumatin-like protein. OEE2 was found to be phosphorylated and a phosphopeptide (YEDNFDGNSNVSVMVpTPpTDK) was identified. Specifically, the protein levels of OEE2 increased as a result of grafting and displayed a higher abundance in plants during the juvenile and rejuvenated stages. Additionally, SsOEE2 displayed the highest expression levels in Sequoia shoots during the juvenile stage and less expression during the adult stage. The expression levels also steadily increased during grafting. Conclusion: Our results indicate a positive correlation between the gene and protein expression patterns of SsOEE2 and the rejuvenation process, suggesting that this gene is involved in the rejuvenation of Sequoia sempervirens

Establishment of an arabinose-inducible system in Stenotrophomonas maltophilia

A pBBad22T-derived conditioned arabinose (Ara)-inducible expression system was evaluated in Stenotrophomonas maltophilia (an opportunistic pathogen and has gained increasing attention as a cause of healthcare-associated infection). S. maltophilia cannot grow well when Ara is the sole available carbon source. The induction kinetic study, optimal inducer concentration determination, and depletion experiment were performed by using a xylE gene fusion construct, pBxylE, to monitor the expression of pBBad22T in S. maltophilia. For induction survey, the expression of catechol 2,3-dioxygenase (C23O), encoded by xylE gene, continuously increases during an 8-h induced course and can be modulated by different inducer concentrations. The applied induction condition of pBBad22T in S. maltophilia is the inducer concentration ranging from 0.1% to 0.5% for an induction time of 4 h. For repression evaluation, the C23O expression is rapidly turned off within 30 min after the removal of Ara. Accordingly, the established Ara-inducible system can provide a convenient tool for the study of S. maltophilia

Regioselective deacetylation based on teicoplanin-complexed Orf2*crystal structures

Lipoglycopeptide antibiotics are more effective than vancomycin against MRSA as they carry an extra aliphatic acyl side chain on glucosamine (Glm) at residue 4 (r4). The biosynthesis of the r4 N-acyl Glc moiety at teicoplanin (Tei) or A40926 has been elucidated, in which the primary amine nucleophile of Glm is freed from the r4 GlcNac pseudo-Tei precursor by Orf2* for the subsequent acylation reaction to occur. In this report, two Orf2* structures in complex with beta-D-octyl glucoside or Tei were solved. Of the complexed structures, the substrate binding site and a previously unknown hydrophobic cavity were revealed, wherein r4 GlcNac acts as the key signature for molecular recognition and the cavity allows substrates carrying longer acyl side chains in addition to the acetyl group. On the basis of the complexed structures, a triple-mutation mutant S98A/V121A/F193Y is able to regioselectively deacetylate r6 GlcNac pseudo-Tei instead of that at r4. Thereby, novel analogs can be made at the r6 sugar moiety