Point Defects in Two-Dimensional Indium Selenide as Tunable Single-Photon Sources

In the past few years remarkable interest has been kindled by the development of nonclassical light sources and, in particular, of single-photon emitters (SPE), which represent fundamental building blocks for optical quantum technology. In this Letter, we analyze the stability and electronic properties of an InSe monolayer with point defects with the aim of demonstrating its applicability as an SPE. The presence of deep defect states within the InSe band gap is verified when considering substitutional defects with atoms belonging to group IV, V, and VI. In particular, the optical properties of Ge as substitution impurity of Se predicted by solving the Bethe-Salpeter equation on top of the GW corrected electronic states show that transitions between the valence band maximum and the defect state are responsible for the absorption and spontaneous emission processes, so that the latter results in a strongly peaked spectrum in the near-infrared. These properties, together with a high localization of the involved electronic states, appear encouraging in the quest for novel SPE materials

Nested Dynamics of Metropolitan Processes and Policies: Turin

BACKGROUND PAPERS FOR THE METROPOLITAN STUDY: 3 -- The project "Nested Dynamics of Metropolitan Processes and Policies" was initiated by the Regional and urban Development Group at IIASA in 1983 and work on this collaborative study started the same year. This Series of contributions represents "entry tickets" to the Project, i.e., initial statements by authors from individual metropolitan regions that are participating in the Project's network. The aim of these papers is threefold. First, to provide some background information describing the processes of change within four principal subsystems: population, housing, economy, and transportation. Second, to identify major trends and crucial policy issues which are to constitute a focus for the subsequent analytical and modeling work. Third, to facilitate comparative studies of development paths among these regions and the dynamic interdependencies between the above subsystems. The background information contained in this paper pertains to the Turin metropolitan region

Impact of Power-to-Gas on distribution systems with large renewable energy penetration

The exploitation of the Power-to-Gas (PtG) technology can properly support the distribution system operation in case of large penetration of Renewable Energy Sources (RES). This paper addresses the impact of the PtG operation on the electrical distribution systems. A novel model of the PtG plant has been created to be representative of the entire process chain, as well as to be compatible with network calculations. The structure of the model with the corresponding parameters has been defined and validated on the basis of measurements gathered on a real plant. The PtG impact on the distribution systems has then been simulated on two network models representing a rural and a semi-urban environment, respectively. The testing has been carried out by defining a set of cases that contain critical situations for the distribution network, caused by RES plant placement. The objectives of the introduction of PtG are the reduction of the reverse power flow, as well as the reduction of the overcurrent and overvoltage issues in the distribution system. The results obtained from annual simulations lead to considerable reduction (from 78 to 100%) of the reverse power flow with respect to the base case, and to alleviating (or even solving) the overcurrent and overvoltage problems of the networks. These results indicate PtG as a possible solution for guaranteeing a smooth transition towards decarbonized energy systems. The capacity factors of the PtG plants largely vary depending on the network topology, the RES penetration, the number of the PtG plants and their sizes. From the test cases, the performance in a rural network (where the minimum capacity factor is about 50%) resulted better than in a semi-urban network (where the capacity factor values range between 21% and 60%)

Vitamin D deficiency: A new risk factor for type 2 diabetes?

Recent compelling evidence suggests a role of vitamin D deficiency in the pathogenesis of insulin resistance and insulin secretion derangements, with a consequent possible interference with type 2 diabetes mellitus. The mechanism of this link is incompletely understood. In fact, vitamin D deficiency is usually detected in obesity in which insulin resistance is also a common finding. The coexistence of insulin resistance and vitamin D deficiency has generated several hypotheses. Some cross-sectional and prospective studies have suggested that vitamin D deficiency may play a role in worsening insulin resistance; others have identified obesity as a risk factor predisposing individuals to exhibit both vitamin D deficiency and insulin resistance. The available data from intervention studies are largely confounded, and inadequate considerations of seasonal effects on 25(OH)D concentrations are also a common design flaw in many studies. On the contrary, there is strong evidence that obesity might cause both vitamin D deficiency and insulin resistance, leaving open the possibility that vitamin D and diabetes are not related at all. Although it might seem premature to draw firm conclusions on the role of vitamin D supplementation in reducing insulin resistance and preventing type 2 diabetes, this manuscript will review the circumstances leading to vitamin D deficiency and how such a deficiency can eventually independently affect insulin sensitivity. © 2012 S. Karger AG, Basel

The intracellular trafficking mechanism of Lipofectamine-based transfection reagents and its implication for gene delivery

Lipofectamine reagents are widely accepted as "gold-standard" for the safe delivery of exogenous DNA or RNA into cells. Despite this, a satisfactory mechanism-based explanation of their superior efficacy has remained mostly elusive thus far. Here we apply a straightforward combination of live cell imaging, single-particle tracking microscopy, and quantitative transfection-efficiency assays on live cells to unveil the intracellular trafficking mechanism of Lipofectamine/DNA complexes. We find that Lipofectamine, contrary to alternative formulations, is able to efficiently avoid active intracellular transport along microtubules, and the subsequent entrapment and degradation of the payload within acidic/digestive lysosomal compartments. This result is achieved by random Brownian motion of Lipofectamine-containing vesicles within the cytoplasm. We demonstrate here that Brownian diffusion is an efficient route for Lipofectamine/DNA complexes to avoid metabolic degradation, thus leading to optimal transfection. By contrast, active transport along microtubules results in DNA degradation and subsequent poor transfection. Intracellular trafficking, endosomal escape and lysosomal degradation appear therefore as highly interdependent phenomena, in such a way that they should be viewed as a single barrier on the route for efficient transfection. As a matter of fact, they should be evaluated in their entirety for the development of optimized non-viral gene delivery vectors

Single-fiber conduction velocity test allows earlier detection of abnormalities in diabetes

Introduction: The purpose of this study was to determine whether single-fiber conduction velocity (SF-CV) of a small number of axons increases sensitivity for identification of motor nerve conduction alterations in patients with diabetes. Methods: Twenty-one consecutive diabetic patients in good metabolic control were studied. For each patient, conventional (C-CV) and SF-CV results were correlated with the presence of neuropathic symptoms. Results: Nine of 21 patients reported symptoms suggestive of mild nerve impairment. Three patients had abnormal sural nerve CV, 1 of whom also had abnormal motor nerve conduction. Eighteen patients had normal findings on conventional tests, 3 of whom had slowing of SF-CV. Conclusions: SF-CV is able to detect mild myelin damage with higher sensitivity than conventional tests. The use of SF-CV may be a helpful tool in the early identification of diabetic polyneuropathy, and it may be useful for tailoring an approach to diabetic polyneuropathy. © 2010 Wiley Periodicals, Inc