Hydrogen-Induced High-Temperature Superconductivity in Two-Dimensional Materials: The Example of Hydrogenated Monolayer MgB_{2}.

Hydrogen-based compounds under ultrahigh pressure, such as the polyhydrides H_{3}S and LaH_{10}, superconduct through the conventional electron-phonon coupling mechanism to attain the record critical temperatures known to date. Here we exploit the intrinsic advantages of hydrogen to strongly enhance phonon-mediated superconductivity in a completely different system, namely, a two-dimensional material with hydrogen adatoms. We find that van Hove singularities in the electronic structure, originating from atomiclike hydrogen states, lead to a strong increase of the electronic density of states at the Fermi level, and thus of the electron-phonon coupling. Additionally, the emergence of high-frequency hydrogen-related phonon modes in this system boosts the electron-phonon coupling further. As a concrete example, we demonstrate the effect of hydrogen adatoms on the superconducting properties of monolayer MgB_{2}, by solving the fully anisotropic Eliashberg equations, in conjunction with a first-principles description of the electronic and vibrational states, and their coupling. We show that hydrogenation leads to a high critical temperature of 67 K, which can be boosted to over 100 K by biaxial tensile strain.

Free surfaces recast superconductivity in few-monolayer MgB2: Combined first-principles and ARPES demonstration.

Two-dimensional materials are known to harbour properties very different from those of their bulk counterparts. Recent years have seen the rise of atomically thin superconductors, with a caveat that superconductivity is strongly depleted unless enhanced by specific substrates, intercalants or adatoms. Surprisingly, the role in superconductivity of electronic states originating from simple free surfaces of two-dimensional materials has remained elusive to date. Here, based on first-principles calculations, anisotropic Eliashberg theory, and angle-resolved photoemission spectroscopy (ARPES), we show that surface states in few-monolayer MgB2 make a major contribution to the superconducting gap spectrum and density of states, clearly distinct from the widely known, bulk-like σ- and π-gaps. As a proof of principle, we predict and measure the gap opening on the magnesium-based surface band up to a critical temperature as high as ~30 K for merely six monolayers thick MgB2. These findings establish free surfaces as an unavoidable ingredient in understanding and further tailoring of superconductivity in atomically thin materials.

Structural and electronic properties of defects at grain boundaries in CuInSe2.

We report on a first-principles study of the structural and electronic properties of a Σ3 (112) grain boundary model in CuInSe2. The study focuses on a coherent, stoichiometry preserving, cation-Se terminated grain boundary, addressing the properties of the grain boundary as such, as well as the effect of well known defects in CuInSe2. We show that in spite of its apparent simplicity, such a grain boundary exhibits a very rich phenomenology, providing an explanation for several of the experimentally observed properties of grain boundaries in CuInSe2 thin films. In particular, we show that the combined effect of Cu vacancies and cation antisites can result in the observed Cu depletion with no In enrichment at the grain boundaries. Furthermore, Cu vacancies are unlikely to produce a hole barrier at the grain boundaries, but Na may indeed have such an effect. We find that Na-on-Cu defects will tend to form abundantly at the grain boundaries, and can provide a mechanism for the carrier depletion and/or type inversion experimentally reported.

[Psychopathology of the misuse of Subutex®: The Popeye syndrome]. / Psychopathologie des mésusages du Subutex® : le syndrome de Popeye.

INTRODUCTION: High dose buprenorphine (HDB), commonly known as Subutex(®), is nowadays largely prescribed as a replacement therapy for major opiate dependence. Its sublingual administration allows a decrease in the withdrawal syndrome accompanying opiate abuse cessation. Over the past few decades, epidemiological data on people on replacement therapy have emphasized an increase in the misuse of Subutex(®) and more specifically intravenous injections of HDB. These growing practices pave the way to major physical consequences or even death. Several studies have highlighted the infectious, vascular, venous and arterial (pseudo-aneurysm) complications stemming from this habit. Among the possible vascular complications, we can notice the presence of abscess, venous thrombosis, phlegmons, skin necrosis, cellulite, and profound and superficial thrombophlebitis at injection sites. These can evolve into chronic edemas of the tips and subcutaneous nodules. The Popeye syndrome is one of the possible complications of this misuse. This syndrome is characterized by the swelling of both sides of the forearms and hands. These edemas tend to become persistent and to be paired with tissue changes such as skin thickening. Besides, the increase in the hands volume can occur bilaterally or sometimes in an asymmetrical way, accentuated on the hand of the non-dominant limb. This syndrome does not decrease, or just a little, after the stoppage of injections. It can have a psychological, social, psychopathological and esthetic impact. OBJECTIVES: In this article, we will focus on the clinical case of a 43-year-old man, who is hospitalized in an addictology unit for massive injections of HDB. This patient suffers from a Popeye syndrome as well as from an alcoholic dependence. METHOD: Following the description of psychopathological disorders, our analysis will originate from a clarification relative to the specificities of the practice of intravenous HDB injection to better sharpen the understanding of these misuses in their psychopathological and clinical aspects. We will discuss some proposals for interventions aiming at taking better care of the people suffering from a drug addiction characterized by the injection of HDB replacement therapy. RESULTS: Adam requested an admission in an addictology ward for treatment of a self-medication by Subutex started 4 years ago. A certain awkwardness can be perceived when he lays his highly damaged and marked hands on the desk. His upper limbs, thus on display, have tripled in volume: this indicates the presence of a Popeye syndrome, consequence of repeated Subutex injections. These observations lead us to question the function and the sense of this injection behavior in the mental economy, as this repeated behavior engages the body specifically. This bruised body, marked with repeated injection holes has become a place of inscription, of representation that shows the impossibility to access other ways of expression. In this sense, taking action is becoming an act of speech. Within this speech, we can notice the existence of a profound state of uneasiness. To put up with the painful feeling of inner emptiness that is calling for a necessary filling, aiming at re-establishing a frail balance, Adam appeals to repeated injections. However, when the tortured body signifies its incapacity to receive an ultimate injection, thus showing its limits and the destruction it is undergoing, it is no longer possible to resort to Subutex injections. As a consequence, Adam came up with the idea of quitting. The withdrawal was initiated by himself and not coupled with medical care. It has led him to feel a gap, beyond the physical uneasiness. Adam has tried to fill in this unbearable feeling of empty body with tobacco, alcohol and food. The body, highly mobilized, translates the presence of a physical conflict where a massive mental anxiety is expressed in a hidden way. During the interview, Adam also addressed the repetitive familial pattern and the transgeneration effects. He seems to be fully aware of these. DISCUSSION: Several perspectives can be addressed as part of Adam's treatment and especially cognitive-behavioral therapies as they could prove to be of a certain interest. The aim of this therapy would thus be to assess the motivation for change in order to begin a psychotherapeutic work based on personal adherence to the cessation of this misuse. This could be set up in parallel with an anxiety management work. CONCLUSION: A better understanding and an extensive knowledge of the possible complications linked to the misuse of HDB seems necessary to sensitize and better inform people who suffer from high-risk behaviors and also to enable a more adapted care.

Native point defects in CuIn(1-x)Ga(x)Se2: hybrid density functional calculations predict the origin of p- and n-type conductivity.

We have performed a first-principles study of the p- and n-type conductivity in CuIn(1-x)Ga(x)Se2 due to native point defects, based on the HSE06 hybrid functional. Band alignment shows that the band gap becomes larger with x due to the increasing conduction band minimum, rendering it hard to establish n-type conductivity in CuGaSe2. From the defect formation energies, we find that In/GaCu is a shallow donor, while V(Cu), V(In/Ga) and Cu(In/Ga) act as shallow acceptors. Using the total charge neutrality of ionized defects and intrinsic charge carriers to determine the Fermi level, we show that under In-rich growth conditions InCu causes strongly n-type conductivity in CuInSe2. Under increasingly In-poor growth conditions, the conductivity type in CuInSe2 alters to p-type and compensation of the acceptors by In(Cu) reduces, as also observed in photoluminescence experiments. In CuGaSe2, the native acceptors pin the Fermi level far away from the conduction band minimum, thus inhibiting n-type conductivity. On the other hand, CuGaSe2 shows strong p-type conductivity under a wide range of Ga-poor growth conditions. Maximal p-type conductivity in CuIn(1-x)Ga(x)Se2 is reached under In/Ga-poor growth conditions, in agreement with charge concentration measurements on samples with In/Ga-poor stoichiometry, and is primarily due to the dominant acceptor Cu(In/Ga).

Local Observation of Field Polarity Dependent Flux Pinning by Magnetic Dipoles.

A scanning Hall probe microscope is used to study flux pinning in a thin superconducting Pb film covering a square array of single-domain Co dots with in-plane magnetization. We show that single flux quanta of opposite sign thread the superconducting film below T(c) at the opposite poles of these dipoles. Depending on the polarity of the applied field, flux lines are attracted to a specific pole of the dipoles, due to the direct interaction with the vortexlike structures induced by the local stray field.

Malignant myoepithelioma of the breast. Case report with immunohistochemical study.

Malignant myoepitheliomas of the breast are rare. We report a case of spindle cell malignant myoepithelioma studied by light microscopy and immunohistochemistry. The malignant myoepithelial cells stained positively for cytokeratins, smooth muscle actin and vimentin, but not for epithelial membrane antigen. The tumor showed a focal positivity for S100 protein. A short review of the morphology and immunohistochemistry of cases reported in the international literature is given in a table. Morphologically malignant myoepitheliomas can be subdivided into spindle cell malignant myoepitheliomas and malignant adenomyoepitheliomas.

Tetrasomy 9p: prenatal diagnosis and fetopathological findings in a second trimester male fetus.

In this report the authors describe the fetopathological findings in a second trimester male fetus with pure 9p tetrasomy. The prenatal diagnosis was based on the echographic finding of severe internal anomalies of the central nervous, cardiovascular and urogenital systems.

Causative role of Yersinia and other enteric pathogens in the appendicular syndrome.

In 2,861 consecutive patients undergoing appendicectomy for clinically suspected appendicitis an enteric pathogen was isolated from the appendix in almost 7% using an optimal combination of culture media. The pathogenic Yersinia enterocolitica serotypes 03 and 09 predominated (3.6%), followed by Campylobacter and nontyphoid Salmonella. The same pathogen was isolated from the stool in 72.5% of patients with a culture-positive appendix and in 84.1% of those positive for a pathogenic Yersinia. Conversely, no pathogenic Yersinia were isolated in 326 gynaecologic control patients, in whom a normal appendix was removed. No frank appendicitis but mesenteric adenitis and/or terminal ileitis were found in 62.3% of 138 patients with a culture positive appendix, and in 74.6% of those positive for a pathogenic Yersinia. Histologic findings available in 135 patients showed acute suppurative appendicitis in only six (4.5%) patients, and in only one of 73 (1.4%) positive for a pathogenic Yersinia. In contrast, 46.8% of a group of 345 culture-negative appendices showed acute inflammation. A positive stool culture in a patient with suspected appendicitis, if consistent with sonographic and clinical findings, should be taken as strong evidence against the presence of true appendicitis.

The role of lordosis.

A majority of degenerative changes in the vertebral discs, the facet joints or even the interspinous ligaments, as in Baastrup's disease, are probably caused by pressure damage. Among the various causes of overloading, hyperlordosis--alone or in combination with other adjuvant causes--is presumably the most important one. Its detrimental influence is most noticeable in some peculiar situations, where lordosis is the common denominator of malformations of different origins, as, for instance, dorsal and dorsolumbar kyphosis, L4-5 facetarthrosis with L5-S1 spondylolisthesis, and posterior or posterolateral distraction arthrodesis. It is now recognized that arthrodesis in the lumbar spine should be done in normal lordosis or even slight hyperlordosis in order to respect, or even to improve the stress distribution in the mobile segments. After lumbosacral arthrodesis, as well as in common "everyday" low back pain problems, protection of the disks and facet joints from prolonged continuous loading is essential for the prevention of continuing degeneration.

Hypoglycemia owing to inappropriate glucagon secretion treated with a continuous subcutaneous glucagon infusion system.

A selective glucagon deficiency was documented in a 36-year-old female patient suffering from severe hypoglycemic attacks. The extremely low fasting plasma glucagon levels could not be stimulated by hypoglycemia. The increase in plasma glucagon during stimulation with arginine did not prevent hypoglycemia provoked by the simultaneous insulin secretion. Treatment consisting of a continuous sc glucagon infusion system resulted in correction of both postabsorptive and postprandial hypoglycemia. Further lowering of the glucose level during an arginine test could be the hallmark of this hypoglycemic syndrome characterized by an inappropriate glucagon secretion. This case report would indicate that epinephrine cannot prevent hypoglycemia when glucagon release is completely deficient.

Diabetic ketoacidosis-induced hyperkalemia. Prevalence and possible origin.

We report the biochemical data of 22 hospital admissions because of untreated diabetic ketoacidosis. Fifty percent of admitted patients showed an initial serum potassium between 4.6 and 6.0 mEq/l whereas severe hyperkalemia (value greater than 6.1 mEq/l) occurred in 32%. Initial potassium levels show a slight negative correlation with pH but a stronger correlation (p less than 0.001) was found between the initial serum potassium and glucose values. We suggest that hyperglycemia due to insulinopenia must be one of the factors in the pathogenesis of this hyperkalemia.

Biochemical and histochemical analysis of steroid hormone binding sites in human primary breast cancer.

Mammary carcinoma tissue from 514 primary breast cancer patients were all biochemically and histochemically analyzed for both estrogen receptors and progesterone receptors. The dextran-coated charcoal (DCC) method measured the ER and PR as defined by Scatchard analysis, ligand competition experiments and target organ specificity. The ligands, estradiol-6-carboxymethyloxime-BSA-fluoresceine isothiocyanate and hydroxyprogesteronehemisuccinate-BSA-tetramethylrhodamine isothiocyanate, used for histochemistry, did not bind to either ER or PR and were mainly bound to the membrane fraction of isolated breast cancer cells. Fluorescence was not specifically inhibited by estrogens or progestogens. In addition, "estrogenic" always coincided with "progestogenic" fluorescence. The binding of the fluoresceine compounds to tissue slides depended on the large steroid hormone substitution on the bovine serum albumin molecule. Clinical parameters, known to be related to ER and PR did not correlate with the histochemical results. The observations indicated the impossibility of specific steroid receptor detection by the histochemical method. Therefore, up to the present, evaluation of hormone dependency and prognosis in human breast cancer cannot be based on this approach.

Anthropometric and calorimetric evidence for the protein sparing effects of a new protein supplemented low calorie preparation.

A commercial protein sparing modified fast (PSMF) preparation has been evaluated for the protein sparing effects in 15 morbidly obese patients. During a 500 kcal preparation, given during a 6-week period, mean body weight and BMI decreased significantly. Total body fat decreased from 55.8 to 41.4 kg and lean body mass and arm muscle circumference (AMC) remained unchanged. Using indirect calorimetry and under the same degree of energy expenditure, carbohydrate metabolic consumption was significantly diminished (166 to 61 g/24 hr; p less than 0.001) but fat consumption was increased (116 to 155 g/24 hr; p less than 0.05) while the metabolic turn-over of protein was unchanged. This new presented PSMF preparation seems to present the typical properties of a protein sparing modified fast.

Determination of free thyroid hormones and their binding proteins in a patient with severe hyperthyroidism (thyroid storm?) and thyroid encephalopathy.

A patient with severe hyperthyroidism (thyroid storm?) and thyroid encephalopathy is described. During her illness only a slightly raised level of total thyroxine and a normal level of total triiodothyronine was found in contrast with very high levels of free thyroid hormones. Very low levels of thyroxine binding globulin, albumin and low levels of thyroxine binding prealbumin in contrast with nearly normal values of T3 resin uptake were observed. All parameters of thyroid function returned to normal after therapy.