Effect of connectivity on the carrier transport and recombination dynamics of perovskite quantum dot networks

Quantum dot (QD) solids are being widely exploited as a solution-processable technology to develop photovoltaic, light-emission, and photo-detection devices. Charge transport in these materials is the result of a compromise between confinement at the individual QD level and electronic coupling among the different nanocrystals in the ensemble. While this is commonly achieved by ligand engineering in colloidal-based systems, ligand-free QD assemblies have recently emerged as an exciting alternative where nanostructures can be directly grown into porous matrices with optical quality as well as control over their connectivity and hence charge transport properties. In this context, we present a complete photophysical study comprising fluence and temperature-dependent time-resolved spectroscopy to study carrier dynamics in ligand-free QD networks with gradually varying degrees of interconnectivity, which we achieve by changing the average distance between the QDs. Analysis of the photoluminescence and absorption properties of the QD assemblies, involving both static and time-resolved measurements, allows us to identify the weight of the different recombination mechanisms, both radiative and non-radiative, as a function of QD connectivity. We propose a picture where carrier diffusion, which is needed for any optoelectronic application and implies inter-particle transport, gives rise to the exposure of carriers to a larger defect landscape than in the case of isolated QDs. The use of a broad range of fluences permits extracting valuable information for applications demanding either low or high carrier injection levels and highlighting the relevance of a judicious design to balance recombination and diffusion.Comment: 16 pages, 5 figures in main manuscript; 11 pages, 11 figures in Supporting Informatio

Estrogen Promotes Mandibular Condylar Fibrocartilage Chondrogenesis and Inhibits Degeneration via Estrogen Receptor Alpha in Female Mice

Temporomandibular joint degenerative disease (TMJ-DD) is a chronic form of TMJ disorder that specifically afflicts people over the age of 40 and targets women at a higher rate than men. Prevalence of TMJ-DD in this population suggests that estrogen loss plays a role in the disease pathogenesis. Thus, the goal of the present study was to determine the role of estrogen on chondrogenesis and homeostasis via estrogen receptor alpha (ERα) during growth and maturity of the joint. Young and mature WT and ERαKO female mice were subjected to ovariectomy procedures and then given placebo or estradiol treatment. The effect of estrogen via ERα on fibrocartilage morphology, matrix production, and protease activity was assessed. In the young mice, estrogen via ERα promoted mandibular condylar fibrocartilage chondrogenesis partly by inhibiting the canonical Wnt signaling pathway through upregulation of sclerostin (Sost). In the mature mice, protease activity was partly inhibited with estrogen treatment via the upregulation and activity of protease inhibitor 15 (Pi15) and alpha-2- macroglobulin (A2m). The results from this work provide a mechanistic understanding of estradiol on TMJ growth and homeostasis and can be utilized for development of therapeutic targets to promote regeneration and inhibit degeneration of the mandibular condylar fibrocartilage.National Institute of Dental & Craniofacial Research of the National Institutes of Health under Award Numbers R56DE020097 (SW) and F32DE026366 (JR

Exchange Market Reform, Inflation, and Fiscal Deficits

This paper examines the short- and long-run effects of exchange market reform in developing countries. The first part reviews the recent experience of Guyana, India, Jamaica, Kenya, Sierra Leone, and Sri Lanka with exchange market reform. The second part studies analytically the short-run dynamics of the parallel market premium and the money supply upon unification, when the post-reform regime consists of either a pure float or a managed float. The third part discusses the impact of unification on inflation and quasi-fiscal deficits, and identifies a variety of implicit taxes and subsidies that must be taken into account in assessing the longer-run effects of exchange market reform.

Fiscal Imbalances, Capital Inflows, and the Real Exchange Rate

This paper examines the links between fiscal policy, capital inflows, and the real exchange rate in Turkey since the late 1980s. After an overview of recent macroeconomic developments in Turkey, a vector autoregression model is estimated linking government spending, interest rate differentials, capital inflows, and the temporary component of the real exchange rate. Positive shocks to government spending and capital inflows lead to an appreciation of the temporary component of the real exchange rate, whereas positive shocks to the uncovered interest rate differential lead to a capital inflow and an appreciation of the temporary component of the real exchange rate. The findings highlight the role of fiscal adjustment in restoring macroeconomic stability.

3D guided dental implant placement: impact on surgical accuracy and collateral damage to the inferior alveolar nerve

An increase in the number of implants placed has led to a corresponding increase in the number of complications reported. The complications can vary from restorative complications due to poor placement to damage to collateral structures such as nerves and adjacent teeth. A large majority of these complications can be avoided if the implant has been placed accurately in the optimal po-sition. Therefore, the aim of this in vitro pilot study was to investigate the effect of freehand (FH) and fully guided (FG) surgery on the accuracy of implants placed in close proximity to vital structures such as the inferior alveolar nerve (IAN). Cone-beam computed tomography (CBCT) and intraoral scans of 6 patients who have had previous dental implants in the posterior mandible were used in this study. The ideal implant position was planned. FG surgical guides were man-ufactured for each case. In this study, the three dimensional 3D printed resin models of each of the cases were produced and the implants placed using FG and FH methods on the respective models. The outcome variables of the study, angular deviations were calculated and the distance to the IAN was measured. The mean deviations for the planned position observed were 1.10 mm coronally, 1.88 mm apically with up to 6.3 degrees’ angular deviation for FH surgery. For FG surgical technique the mean deviation was found to be at 0.35 mm coronally, 0.43 mm apically with 0.78 degrees angularly respectively. The maximum deviation from the planned position for the apex of the implant to the IAN was 2.55 mm using FH and 0.63 mm FG. This bench study, within its limitations, demonstrated surgically acceptable accuracy for both FH and FG techniques that would allow safe placement of implants to vital structures such as the IAN when a safety zone of 3mm is allowed. Nevertheless, a better margin of error was observed for FG surgery with respect to the angular deviation and controlling the distance of the implant to the IAN using R2 Gate ® system

Sub-Saharan Africa

This paper assesses the economic performance during 1986-93 of sub-Saharan African countries as a group and of selected analytical subgroups of countries.

Effects of Macroeconomic Stabilityon Growth, Savings, and Investment in Sub-Saharan Africa

The analysis of this paper indicates that the unsatisfactory overall economic performance of sub-Saharan African countries during 1986–93 was due to inappropriate policies pursued by a number of countries. The countries that have pursued broadly appropriate adjustment policies have performed much better, achieving positive per capita GDP growth. The analysis is supported with an econometric investigation of the effects of macroeconomic policies, structural reforms, and exogenous factors on economic performance. The results indicate that progress in achieving macroeconomic stability and implementing structural reforms have been conducive to better growth, savings, and private investment.