Enhancing the Electrical Conductivity and Long-Term Stability of PEDOT:PSS Electrodes through Sequential Treatment with Nitric Acid and Cesium Chloride.

Solution-processable poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) is an important polymeric conductor used extensively in organic flexible, wearable, and stretchable optoelectronics. However, further enhancing its conductivity and long-term stability while maintaining its superb mechanical properties remains challenging. Here, a novel post-treatment approach to enhance the electrical properties and stability of sub-20-nm-thin PEDOT:PSS films processed from solution is introduced.

Tuning Hole-Injection in Organic-Light Emitting Diodes with Self-Assembled Monolayers.

Improving hole injection through the surface modification of indium tin oxide (ITO) with self-assembled monolayers (SAMs) is a promising method for modulating the carrier injection in organic light-emitting diodes (OLEDs). However, developing SAMs with the required characteristics remains a daunting challenge. Herein, we functionalize ITO with various phosphonic acid SAMs and evaluate the SAM-modified anodes in terms of their work function (WF), molecular distribution, coverage, and electrical conductivity.

Interfacial Reconstructed Layer Controls the Orientation of Monolayer Transition-Metal Dichalcogenides.

Growing continuous monolayer films of transition-metal dichalcogenides (TMDs) without the disruption of grain boundaries is essential to realize the full potential of these materials for future electronics and optoelectronics, but it remains a formidable challenge. It is generally believed that controlling the TMDs orientations on epitaxial substrates stems from matching the atomic registry, symmetry, and penetrable van der Waals forces. Interfacial reconstruction within the exceedingly narrow substrate-epilayer gap has been anticipated.

Higher order exceptional points in infinite lattices.

One of the hallmarks of non-Hermitian photonics is the existence of unique degeneracies, the so-called higher order exceptional points (HEPs). So far, HEPs have been examined mostly in finite coupled systems. In this paper, we present a systematic way to construct infinite optical waveguide lattices that exhibit exceptional points of higher order.

Chlorine-Infused Wide-Band Gap p-CuSCN/n-GaN Heterojunction Ultraviolet-Light Photodetectors.

Copper thiocyanate (CuSCN) is a p-type semiconductor that exhibits hole-transport and wide-band gap (∼3.9 eV) characteristics. However, the conductivity of CuSCN is not sufficiently high, which limits its potential application in optoelectronic devices.

Formation and properties of iodine- and acetonitrile-functionalized two-dimensional Si materials: a Density Functional Theory study.

Topotactic transformations of suitable layered three-dimensional precursors are among the most robust methods to prepare two-dimensional (2D) materials based on silicon or germanium. Here we use Density Functional Theory calculations to probe the mechanisms underlying the formation of 2D-Si sheets functionalized with iodine atoms (SiI) or acetonitrile molecules [Si(MeCN)] starting from a layered CaSi precursor. We identify the sequence of exothermic surface reactions that enable the adsorption of, not only iodine atoms, but, surprisingly, also of solvent acetonitrile molecules on both sides of the top layer of a Si-terminated CaSi surface and its ensuing exfoliation as a standalone 2D sheet.

18.4 % Organic Solar Cells Using a High Ionization Energy Self-Assembled Monolayer as Hole-Extraction Interlayer.

Self-assembled monolayers (SAMs) based on Br-2PACz ([2-(3,6-dibromo-9H-carbazol-9-yl)ethyl]phosphonic acid) 2PACz ([2-(9H-Carbazol-9-yl)ethyl]phosphonic acid) and MeO-2PACz ([2-(3,6-dimethoxy-9H-carbazol-9-yl)ethyl]phosphonic acid) molecules were investigated as hole-extracting interlayers in organic photovoltaics (OPVs). The highest occupied molecular orbital (HOMO) energies of these SAMs were measured at -6.01 and -5.

Nonlinear tuning of PT symmetry and non-Hermitian topological states.

Topology, parity-time (PT) symmetry, and nonlinearity are at the origin of many fundamental phenomena in complex systems across the natural sciences, but their mutual interplay remains unexplored. We established a nonlinear non-Hermitian topological platform for active tuning of PT symmetry and topological states. We found that the loss in a topological defect potential in a non-Hermitian photonic lattice can be tuned solely by nonlinearity, enabling the transition between PT-symmetric and non-PT-symmetric regimes and the maneuvering of topological zero modes.

Two-dimensional thio- and seleno-cyanates of Mo and W.

The stability of two-dimensional (2D) transition metal di-chalcogenides (TMDC) is controlled by the fact that sulfur or selenium atoms can cap the 2D layers without exposing highly reactive bonds. Here we use first-principles calculations to show that a similar structural motif can stabilize Mo- and W-based 2D materials with thio- or seleno-cyanate groups. In particular, we show that the formation of Mo(SeCN), W(SCN) and W(SeCN) sheets is energetically favorable and can lead to various configurations that resemble the well-known polymorphs of TMDCs.

Two-dimensional Mo(SCN): a novel MoS-variant.

Transition metal dichalcogenides (TMDC) are currently among the most studied two-dimensional (2D) materials. Based on first-principles calculations we propose a new family of 2D materials which resemble TMDC's, but contain more complex chemical groups instead of elemental chalcogen atoms. In particular, we identify various stable 2D polymorphs of molybdenum di-thiocyanate, Mo(SCN), with structures akin to those of MoS.

Chemical routes to modify, uplift, and detach a silicene layer from a metal substrate.

Experimental studies have shown that honeycomb silicene layers can grow on various metal substrates. Here we demonstrate using first-principles calculations that hydrogenation and calcium intercalation can be employed to break bonds between a silicene overlayer and a silver surface. The end result of the former process is the creation of a silicane mono-layer, a wide band-gap semiconductor.

Response of silicane and germanane to uni-axial compression: superstructures, polymorph nano-ribbons, and extreme bending.

Germanane (GeH) and silicane (SiH) are the fully hydrogenated forms of germanene and silicene, the Ge- and Si-analogues of graphene. Here we use density-functional theory calculations to probe the properties of GeH and SiH sheets and their dependence on applied uni-axial compression. We find that GeH polymorphs with distinct hydrogen arrangements have markedly different energy band gaps.

Stability and electronic properties of ultrathin films of silicon and germanium.

Recent studies have examined the possibility of growing honeycomb silicene and germanene, the silicon and germanium analogues of graphene. Here we use first-principles calculations to examine the relative stability of a number of other single-layer structures that are derived from prominent surface reconstructions of group-IV semiconductors. We find that Si single-layers with the geometry of the √3 × √3 reconstruction are more stable than honeycomb silicene.

Structural evolution of single-layer films during deposition of silicon on silver: a first-principles study.

In the quest for the construction of silicene, the silicon analogue of graphene, recent experimental studies have identified a number of distinct ultrathin Si over-layer structures on a Ag(111) surface. Here we use first-principles calculations to probe associated atomic-scale mechanisms that can give rise to this rich behavior of Si wetting layers. We find that the interaction between the Si film and the Ag substrate, neither too strong nor too weak, combined with the possibility of buckling, allows for the incorporation of a number of excess Si adatoms in continuous overlayers with a honeycomb network topology.

Markers of bone metabolism in eugonadal female patients with beta-thalassemia major.

Osteoprotegerin (OPG) and receptor activator of NF-kappaB ligand (RANKL) have been recently implicated in the pathogenesis of various types of osteoporosis. The aim of this study was to investigate bone turnover in eugonadal female patients with this disease and characterize the possible role of the OPG/RANKL system in thalassemia-related bone loss. Markers of bone turnover and bone mineral density (BMD) were measured in 16 eugonadal young females with beta-thalassemia major and 18 age- and sex-matched healthy controls.

Circulating osteoprotegerin and receptor activator of NF-kappaB ligand system in patients with beta-thalassemia major.

Osteoporosis represents an important cause of morbidity in patients with beta-thalassemia major, and its etiology is multifactorial. Thus, the aim of this study was to characterize the possible role of the osteoprotegerin (OPG) and receptor activator of the NF-kappaB ligand (RANKL) system in thalassemia-related bone loss. Serum concentrations of OPG, soluble RANKL (s-RANKL), markers of bone turnover, and lumbar spine bone mineral density (BMD) were measured in random samples of males (n = 29; mean age +/- SEM, 24.

Medical treatment of acromegaly: comorbidities and their reversibility by somatostatin analogs.

Relief of symptoms can be achieved following surgery for growth hormone (GH)-secreting adenomas, as well as after pharmacological therapy with somatostatin analogs. Recently, long-acting somatostatin analog depot formulations, octreotide LAR and lanreotide SR have become available. Somatostatin analogs control GH/insulin-like growth factor (IGF)-1 excess, induce tumor shrinkage in a high proportion of patients, improve symptoms of acromegaly with relatively limited side effects and are successfully administered in patients not suitable for surgery.

Hypoparathyroidism in transfusion-dependent patients with beta-thalassemia.

Hypoparathyroidism is thought to be a rare consequence of iron overload seen in beta-thalassemic transfused patients. This study was conducted to determine the prevalence of hypoparathyroidism in a large number of beta-thalassemic patients, and its potential correlation with the presence of other endocrinopathies caused by iron overload. Serum and urine biochemical parameters were measured in 243 thalassemic patients (136 females and 107 males) in order to determine the prevalence of hypoparathyroidism and evaluate bone turnover.

Evaluation of bone mineral density of the lumbar spine in patients with beta-thalassemia major with dual-energy x-ray absorptiometry and quantitative computed tomography: a comparison study.

Osteoporosis is a common, multifactorial cause of morbidity in patients with beta-thalassemia. The present study was performed to compare bone mineral density (BMD) results in the lumbar spine of thalassemic patients measured by both dual-energy x-ray absorptiometry (DEXA) and quantitative computed tomography (QCT), and to determine their correlations with the markers of bone turnover. BMD was measured in the lumbar spine of 13 regularly transfused patients with beta-thalassemia major by both DEXA and QCT.

Endocrine pancreatic insufficiency in chronic pancreatitis.

Chronic pancreatitis (CP) is considered to be a rare cause of diabetes mellitus. However, in both the developed and developing world, there is an increasing number of patients suffering from pancreatitis probably due to lifestyle changes, which is partially associated with both social factors and the poor health status of immigrants. Owing to these circumstances, CP has evolved with one of the possible causes of diabetes in a selected group of patients and should be included in the differential diagnosis of diabetes.

Effects of estrogen deprivation due to breast cancer treatment.

Breast cancer is one of the main life-threatening diseases that a woman may have to face during her lifetime. The increasing incidence of breast neoplasia reported over the last few decades has led to widespread screening of women resulting in early diagnosis. One common but challenging question for most doctors, after the surgical excision of the lesion, is determination of the ideal adjuvant therapy for their patients for the achievement of maximum life expectancy with the best quality of life.

Infection after total hip arthroplasty.

Total hip joint replacement offers dramatic improvement in the quality of life but deep infection is the most feared complication of this procedure. The infection threatens the function of the joint, the preservation of the limb, and occasionally even the life of the patient. For the surgeon it is a disastrous anticlimax, which follows a procedure that may have given the patient freedom from pain and increased mobility.

Acetabular erosion: a comparison between the Austin Moore and Monk hard top prostheses.

Primary prosthetic replacement has become the method of treatment for acute subcapital fractures of the femur and is now widely accepted as a treatment for elderly patients. This paper presents the incidence of acetabular erosion by Monk (hard top) hip prostheses for subcapital fractures as compared with that by Austin Moore prostheses.

Isolated palsy of the nerve to flexor pollicis longus.

Two cases of isolated paralysis of the nerve to flexor pollicis longus are described, both of which recovered after division of constricting fibrous bands. Anatomical considerations and treatment are described.

Total knee replacement in osteoarthritis and rheumatoid arthritis.

Between 1974 and 1983, 187 total knee replacements were performed in 163 patients at four East Kent district general hospitals. With few exceptions pain was the most common indication for the operation and it produced complete or almost complete relief in 90% of cases. The most frequently used prostheses were the Attenborough, Stanmore and Geomedic.