Rehybridization of electronic structure in compressed two-dimensional quantum dot superlattices

Two-dimensional superlattices of organically passivated 2.6-nm silver quantum dots were prepared as Langmuir monolayers and transferred to highly oriented pyrolytic graphite substrates. The structural and electronic properties of the films were probed with variable temperature scanning tunneling microscopy. Particles passivated with decanethiol (interparticle separation distance of ∼1.1±0.2 nm) exhibited Coulomb blockade and staircase. For particles passivated with hexanethiol or pentanethiol (interparticle separation distance of ∼0.5±0.2 nm), the single-electron charging was quenched, and the redistribution of the density of states revealed that strong quantum mechanical exchange, i.e., wave-function hybridization, existed among the particles in these films

Shell structure and electron-electron interaction in self-assembled InAs quantum dots

Using far-infrared spectroscopy, we investigate the excitations of self-organized InAs quantum dots as a function of the electron number per dot, 1<n<6, which is monitored in situ by capacitance spectroscopy. Whereas the well-known two-mode spectrum is observed when the lowest s - states are filled, we find a rich excitation spectrum for n=3, which reflects the importance of electron-electron interaction in the present, strongly non-parabolic confining potential. From capacitance spectroscopy we find that the electronic shell structure in our dots gives rise to a distinct pattern in the charging energies which strongly deviates from the monotonic behavior of the Coulomb blockade found in mesoscopic or metallic structures.Comment: 4 pages, 3 PostScript figure

Açaí (Euterpe spp.): características, formação de mudas e plantio para a produção de frutos.

Este trabalho teve como objetivo apresentar informações técnicas gerais sobre as características do açaizeiro, produção de mudas, plantio e manejo para a produção de frutos.bitstream/item/24775/1/ct80-acai.pd

Redesign in the textile industry: Proposal of a methodology for the insertion of circular thinking in product development processes

Despite the growing attention toward negative environmental impacts generated by the textile industry, companies face challenges in achieving sustainable and circular economy (CE) transition. The literature has so far lacked a systematic effort to analyze how textile companies can insert CE elements in their new product development process (NPD), especially regarding the proposition of methodologies that can better assist the companies in this regard. This study aims to identify good green innovation and CE practices in NPD adopted by textile companies and propose a methodology from Design Thinking (DT) to insert circular thinking in NPD. To that end, we conducted the research in two steps: (i) narrative bibliographic review and (ii) field research. The bibliographic review was conducted in the “Web of Science”, “Scopus”, and “Scielo” databases. The field research was executed with four textile companies. Our results show that companies tend to consider socio-environmental aspects at different stages of the development of new products. However, there is opportunities for improvement, especially through the use of ideas from DT. The proposed methodology is composed of two main cycles: the design cycle (DT stages) and the consumption cycle (subsequent stages). It encompasses the five main stages of the DT and the three macro phases of NPD of the textile industry. The ideas coming from the DT, especially creativity, focus on the user and stakeholder integration, assist in the development of innovative and circular solutions. The methodology presents how companies can work on reuse, recycling, and manufacturing issues, so that CE occurs. In the end, we evaluated, together with experts, the applicability of the proposed use of ideas of DT in practical cases. The research advances the discussions on NPD in the textile sector, especially on its potential to contribute to the transition to CE. It explores how DT assists in inserting circular thinking into the NPD and presents alternatives for companies to develop circular products and insert green innovations in their NPD

Metal-Insulator Transition in a Disordered Two-Dimensional Electron Gas in GaAs-AlGaAs at zero Magnetic Field

A metal-insulator transition in two-dimensional electron gases at B=0 is found in Ga(Al)As heterostructures, where a high density of self-assembled InAs quantum dots is incorporated just 3 nm below the heterointerface. The transition occurs at resistances around h/e^2 and critical carrier densities of 1.2 10^11cm^-2. Effects of electron-electron interactions are expected to be rather weak in our samples, while disorder plays a crucial role.Comment: 4 pages, 3 figures, 21 reference

A novel point mutation in a class IV glucose-6-phosphate dehydrogenase variant (G6PD São Paulo) and polymorphic G6PD variants in São Paulo State, Brazil

In this study, we used red cell glucose-6-phosphate dehydrogenase (G6PD) activity to screen for G6PD-deficient individuals in 373 unrelated asymptomatic adult men who were working with insecticides (organophosphorus and carbamate) in dengue prevention programs in 27 cities in São Paulo State, Brazil. Twenty-one unrelated male children suspected of having erythroenzymopathy who were attended at hospitals in São Paulo city were also studied. Fifteen of the 373 adults and 12 of the 21 children were G6PD deficient. G6PD gene mutations were investigated in these G6PD-deficient individuals by using PCR-RFLP, PCR-SSCP analysis and DNA sequencing. Twelve G6PD A-202A/376G and two G6PD Seattle844C, as well as a new variant identified as G6PD São Paulo, were detected among adults, and 11 G6PD A-202A/376G and one G6PD Seattle844C were found among children. The novel mutation c.660C > G caused the replacement of isoleucine by methionine (I220M) in a region near the dimer interface of the molecule. The conservative nature of this mutation (substitution of a nonpolar aliphatic amino acid for another one) could explain why there was no corresponding change in the loss of G6PD activity (64.5% of normal activity in both cases)

Aharonov-Bohm signature for neutral excitons in type-II quantum dot ensembles

It is commonly believed that the Aharonov-Bohm (AB) effect is a typical feature of the motion of a charged particle interacting with the electromagnetic vector potential. Here we present a magnetophotoluminescence study of type-II InP/GaAs self-assembled quantum dots, unambiguously revealing the Aharonov-Bohm-type oscillations for neutral excitons when the hole ground state changes its angular momentum from lh = 0 to lh = 1, 2, and 3. The hole ring parameters derived from a simple model are in excellent agreement with the structural parameters for this system.Comment: Revised version, 10 pages, 3 figure