The Bulletin, series 40, number 2, July (1944)

The state of the collegehttps://red.mnstate.edu/thebulletin/1073/thumbnail.jp

Photophysical and electronic properties of bismuth-perovskite shelled lead sulfide quantum dots

Metal halide perovskite shelled quantum dot solids have recently emerged as an interesting class of solution-processable materials that possess the desirable electronic properties of both quantum dots and perovskites. Recent reports have shown that lead sulfide quantum dots (PbS QDs) with perovskite ligand-shells can be successfully utilized in (opto)electronic devices such as solar cells, photoconductors, and field-effect transistors (FETs), a development attributed to the compatibility of lattice parameters between PbS and certain metal halide perovskites that results in the growth of the perovskite shell on the PbS QDs. Of several possible perovskite combinations used with PbS QDs, bismuth-based variants have been shown to have the lowest lattice mismatch and to display excellent performance in photoconductors. However, they also display photoluminescence (PL), which is highly sensitive to surface defects. In this work, we present an investigation of the transport and optical properties of two types of bismuth-based perovskite (MA(3)BiI(6) and MA(3)Bi(2)I(9)) shelled PbS QDs. Our photophysical study using temperature-dependent PL spectroscopy between 5 and 290 K indicates that the PL efficiency of the reference oleic acid (OA) capped samples is much higher than that of the Bi-shelled ones, which suffer from traps, most likely formed at their surfaces during the phase-transfer ligand exchange process. Nevertheless, the results from electrical measurements on FETs show the successful removal of the native-OA ligands, displaying electron dominated transport with modest mobilities of around 10(-3) cm(2) [V s](-1) - comparable to the reported values for epitaxial Pb-based shelled samples. These findings advance our understanding of perovskite shelled QD-solids and point to the utility of these Bi-based variants as contenders for photovoltaic and other optoelectronic applications. Published under license by AIP Publishing

Apolipoprotein E polymorphism influences postprandial retinyl palmitate but not triglyceride concentrations.

To quantify the effect of the apolipoprotein (apo) E polymorphism on the magnitude of postprandial lipemia, we have defined its role in determining the response to a single high-fat meal in a large sample of (N = 474) individuals taking part in the biethnic Atherosclerosis Risk in Communities Study. The profile of postprandial response in plasma was monitored over 8 h by triglyceride, triglyceride-rich lipoprotein (TGRL)-triglyceride, apo B-48/apo B-100 ratio, and retinyl palmitate concentrations, and the apo E polymorphism was determined by DNA amplification and digestion. The frequency of the apo E alleles and their effects on fasting lipid levels in this sample were similar to those reported elsewhere. Postprandial plasma retinyl palmitate response to a high-fat meal with vitamin A was significantly different among apo E genotypes, with delayed clearance in individuals with an £2 allele, compared with £3/3 and £3/4 individuals. In the sample of 397 Caucasians, average retinyl palmitate response was 1,489 ttg/dl in £2/3 individuals, compared with 1,037 jig/dl in £3/3 individuals and 1,108 Ftg/dl in £3/4 individuals. The apo E polymorphism accounted for 7.1% of the interindividual variation in postprandial retinyl palmitate response, a contribution proportionally greater than its well-known effect on fasting LDL-cholesterol. However, despite this effect on postprandial retinyl palmitate, the profile of postprandial triglyceride response was not significantly different among apo E genotypes. The profile of postprandial response was consistent between the sample of Caucasians and a smaller sample of black subjects. While these data indicate that the removal of remnant particles from circulation is delayed in subjects with the £2/3 genotype, there is no reported evidence that the £2 allele predisposes to coronary artery disease (CAD). The results of this study provide not only a reliable estimate of the magnitude of the effect of the apo E polymorphism on various measurements commonly used to characterize postprandial lipemia, but also provide mechanistic insight into the effects of the apo E gene polymorphism on postprandial lipemia and CAD

Seventy-five mosses and liverworts found frozen with the late Neolithic Tyrolean Iceman: Origins, taphonomy and the Iceman’s last journey

The Iceman site is unique in the bryology of the Quaternary. Only 21 bryophytes (mosses and liverworts) grow now in the immediate vicinity of the 5,300 year old Iceman discovery site at 3,210m above sea level in the Ötztal Alps, Italy. By contrast 75 or more species including at least ten liverworts were recovered as subfossils frozen in, on and around the Iceman from before, at and after his time. About two thirds of the species grow in the nival zone (above 3,000m above sea level) now while about one third do not. A large part of this third can be explained by the Iceman having both deliberately and inadvertently carried bryophytes during his last, fatal journey. Multivariate analyses (PCA, RDA) provide a variety of explanations for the arrivals of the bryophytes in the rocky hollow where the mummy was discovered. This is well into the nival zone of perennial snow and ice with a very sparse, non-woody flora and very low vegetation cover. Apart from the crucial anthropochory (extra-local plants), both hydrochory (local species) and zoochory (by wild game such as ibex of both local and extra-local species) have been important. Anemochory of mainly local species was of lesser importance and of extra-local species probably of little or no importance. The mosses Neckera complanata and several other ecologically similar species as well as a species of Sphagnum (bogmoss) strongly support the claim that the Iceman, took northwards up Schnalstal, South Tyrol, as the route of the last journey. A different species of bogmoss, taken from his colon is another indication the Iceman’s presence at low altitude south of Schnalstal during his last hours when he was first high up, low down and finally at over 3,000m

Internal hydrocephalus combined with pachygyria in a wild-born brown bear cub

An abandoned wild-born male brown bear (Ursus arctos) cub of the year was found and subsequently placed in a zoo. At 7 months of age, the cub showed first signs of ataxia, and at 13 months of age, it was unable to move the hind legs and exhibited outbursts of aggressive behavior and self-mutilation. The animal was euthanized, and necropsy revealed alterations of the brain with obviously flattened gyri, profound enlargement of both lateral ventricles and considerable accumulation of cerebrospinal fluid, disruption of the septum pellucidum, and atrophy of the hippocampus. The animal was diagnosed with an internal hydrocephalus and pachygyria. Genetic evidence showed that the father of the described cub was also the father of the cub’s mother, suggesting the possibility of congenital hydrocephalus

Short-wave infrared colloidal quantum dot photodetectors on silicon

In this paper, two kinds of colloidal quantum dots, PbS and HgTe, are explored for SWIR photodetectors application. The colloidal dots are prepared by hot injection chemical synthesis, with organic ligands around the dots keeping them stable in solution. For the purpose of achieving efficient carrier transport between the dots in a film, these long organic ligands are replaced by shorter, inorganic ligands. We report uniform, ultra-smooth colloidal QD films without cracks realized by dip-coating and corresponding ligand exchange on a silicon substrate. Metal-free inorganic ligands, such as OH- and S2-, are investigated to facilitate the charge carrier transport in the film. Both PbS and HgTe-based quantum dot photoconductors were fabricated on interdigitated gold electrodes. For PbS-based detectors a responsivity of 200A/W is measured at 1.5μm, due to the large internal photoconductive gain. A 2.2μm cut-off wavelength for PbS photodetectors and 2.8μm for HgTe quantum dot photodetectors are obtained

Broadening of Distribution of Trap States in PbS Quantum Dot Field-Effect Transistors with High-k Dielectrics

We perform a quantitative analysis of the trap density of states (trap DOS) in PbS quantum dot field-effect transistors (QD-FETs), which utilize several polymer gate insulators with a wide range of dielectric constants. With increasing gate dielectric constant, we observe increasing trap DOS close to the lowest unoccupied molecular orbital (LUMO) of the QDs. In addition, this increase is also consistently followed by broadening of the trap DOS. We rationalize that the increase and broadening of the spectral trap distribution originate from dipolar disorder as well as polaronic interactions, which are appearing at strong dielectric polarization. Interestingly, the increased polaron-induced traps do not show any negative effect on the charge carrier mobility in our QD devices at the highest applied gate voltage, giving the possibility to fabricate efficient low-voltage QD devices without suppressing carrier transport

2018 Proceedings of the International Conference on Trauma Surgery Technology in Giessen

The overarching goal of the gathering was to define a concept for technology design research in Giessen to improve patient outcomes through the design of assistive technology that assists both patients and surgeons. The emerging field of regenerative rehabilitation where trauma patients are treated by methods of regenerative medicine promises great improvements for our field, but clinical success is yet to be realised. The symposium was specifically organised to acknowledge and address these issues