A Highly Efficient and Stable Blue-Emitting Cs5 Cu3 Cl6 I2 with a 1D Chain Structure

In the field of photonics, alkali copper(I) halides attract considerable attention as lead-free emitters. The intrinsic quantum confinement effects originating from low-dimensional electronic structure lead to high photoluminescence quantum yields (PLQYs). Among them, Cs₃ Cu₂ I₅ is the most promising candidate, satisfying both high PLQY and air stability. In this study, a strategy to explore a new material meeting these requirements through the use of the mixed-anions of I^- and Cl^- is proposed. The expectation is maintained that the large difference in ionic radii between them likely results in the formation of a novel compound. Consequently, Cs₅ Cu₃ Cl₆ I₂ with a 1D zigzag chain structure is discovered. This material exhibits blue emission (≈462 nm) with a near-unity quantum yield of 95%. An electronic structure calculation reveals that the localized nature of the valence band maximum is crucial in obtaining efficient self-trapped exciton emission. Moreover, the iodine-bridged 1D connectivity significantly enhances the chemical stability of Cs₅ Cu₃ Cl₆ I₂ , compared with the pure chloride phase. The present findings provide a new perspective for developing air-stable alkali copper(I) halides with highly efficient luminescence.

Natural van der Waals heterostructural single crystals with both magnetic and topological properties

Heterostructures having both magnetism and topology are promising materials for the realization of exotic topological quantum states while challenging in synthesis and engineering. Here, we report natural magnetic van der Waals heterostructures of (MnBi₂Te₄) _m (Bi₂Te₃) _n that exhibit controllable magnetic properties while maintaining their topological surface states. The interlayer antiferromagnetic exchange coupling is gradually weakened as the separation of magnetic layers increases, and an anomalous Hall effect that is well coupled with magnetization and shows ferromagnetic hysteresis was observed below 5 K. The obtained homogeneous heterostructure with atomically sharp interface and intrinsic magnetic properties will be an ideal platform for studying the quantum anomalous Hall effect, axion insulator states, and the topological magnetoelectric effect.

On the Origin of the Negative Thermal Expansion Behavior of YCu

Among the intermetallics and alloys, YCu is an unusual material because it displays negative thermal expansion without spin ordering. The mechanism behind this behavior that is caused by the structural phase transition of YCu has yet to be fully understood. To gain insight into this mechanism, we experimentally examined the crystal structure of the low-temperature phase of YCu and discuss the origin of the phase transition with the aid of thermodynamics calculations. The result shows that the high-temperature (cubic CsCl-type) to low-temperature (orthorhombic FeB-type) structural phase transition is driven by the rearrangement of three covalent bonds, namely, Y-Cu, Y-Y, and Cu-Cu, which compete for the bonding energy and phonon entropy. At low temperatures, the mixing of Y and Cu does not take place easily because of the weak attractive force between these atoms expected from the small negative mixing enthalpy. This causes all three interactions to take part in the bonding, and Y and Cu are segregated to form an FeB-type structure, which is stabilized by internal energy. At higher temperatures, Cu ions are bound loosely with Y ions due to the large Y-Cu distance (3.01 Å), which results in large vibration entropy and stabilizes a CsCl-type crystal structure. In addition, the CsCl-type structure is reinforced by the Y-Y interaction between next-nearest neighbors, resulting in a smaller unit cell volume. The crystal structure has the simple cubic framework of Y containing Cu ions bound loosely at the cavity sites. The calculated frequency of the Y-like phonon modes is much higher than that of the Cu-like modes, indicating the presence of Y-Y covalent interactions in the CsCl-type phase.

Acid-durable electride with layered ruthenium for ammonia synthesis: boosting the activity via selective etching

We reported LnRuSi as a B₅-site-free Ru catalyst for ammonia synthesis, and its activity enhanced 2–4-fold by selective etching with EDTA-2Na.

Ruthenium (Ru) loaded catalysts are of significant interest for ammonia synthesis under mild reaction conditions. The B₅ sites have been reported as the active sites for ammonia formation, i.e., Ru with other coordinations were inactive, which has limited the utilization efficiency of Ru metal. The implantation of Ru into intermetallic compounds is considered to be a promising approach to tune the catalytic activity and utilization efficiency of Ru. Here we report an acid-durable electride, LnRuSi (Ln = La, Ce, Pr and Nd), as a B₅-site-free Ru catalyst. The active Ru plane with a negative charge is selectively exposed by chemical etching using disodium dihydrogen ethylenediaminetetraacetate (EDTA-2Na) acid, which leads to 2–4-fold enhancement in the ammonia formation rate compared with that of the original catalyst. The turnover frequency (TOF) of LnRuSi is estimated to be approximately 0.06 s^–1, which is 600 times higher than that of pure Ru powder. Density functional theory (DFT) calculations revealed that the dissociation of N₂ occurs easily on the exposed Ru plane of LaRuSi. This systematic study provides firm evidence that layered Ru with a negative charge in LnRuSi is a new type of active site that differs significantly from B₅ sites.

Pseudogap Control of Physical and Chemical Properties in CeFeSi-Type Intermetallics

We describe the synthesis of the new ternary compound CaRuSi whose chemical and physical properties help draw a clear picture of how electronic structure controls the behavior of an isostructural series of intermetallics. DFT calculations reveal that an electronic pseudogap arises near the Fermi level ( E_F), corresponding to 14 valence electrons per RuSi unit. The closed-shell-like character is further investigated by comparisons with the electronic structures of CaCoSi (15 electrons), where the E_F lies above the corresponding pseudogap, and its hydride CaCoSiH, where formation of H anions restores the 14-electron count on the metal sublattice, returning the E_F to the pseudogap. The chemical origin of the 14-electron pseudogap is interpreted with a reversed approximation Molecular Orbital analysis. Here, the pseudogap is shown to coincide with the filling of Ru 16 electron configurations isolobal to the d⁸ square planar complexes of coordination chemistry (but where 4 electron pairs are shared covalently between Ru atoms such that only 12 electrons are required), and the occupation of Si lone pairs (2 electrons). Experimentally, the pseudogap is confirmed with heat capacity measurements, which indicate that the 14-electron systems CaRuSi and CaCoSiH each exhibit  a smaller electronic density of states at the E_F than the 15-electron system CaCoSi. Importantly, the 14-electron pseudogap also significantly affects the chemical properties of the compounds, as evidenced by the difference in the stabilities of CaCoSiH and CaRuSiH observed in hydrogen desorption measurements. These results may support the design of functional materials for superconductivity, hydrogen storage, and catalysis involving hydrogenation.

Tiered Electron Anions in Multiple Voids of LaScSi and Their Applications to Ammonia Synthesis

Electrides-compounds in which electrons localized in interstitial spaces periodically serve as anions-have attracted broad attention for their exotic properties, such as extraordinary electron-donating ability. In our efforts to expand this small family of phases, LaScSi emerges as a promising candidate. Its electron count is 2e^- f.u.^-1 in excess of that expected from the Zintl concept, while its structure offers interstitial spaces that can accommodate these extra electrons. Herein, this potential is explored through density functional theory (DFT) calculations and property measurements on LaScSi. DFT calculations (validated by heat capacity and electrical transport measurements) reveal electron density peaks at two symmetry-distinct interstitial sites. Importantly, this electride-like character is combined with chemical stability in air and water, an advantage for catalysis. Ru-loaded LaScSi shows outstanding catalytic activity for ammonia synthesis, with a turnover frequency (0.1 s^-1 at 0.1 MPa, 400 °C) an order of magnitude higher than those of oxide-based Ru catalysts, e.g., Ru/MgO. As with other electrides, LaScSi's ability to reversibly store hydrogen prevents the hydrogen poisoning of Ru surfaces. The better performance of LaScSi, however, hints at the importance of the high concentration (>1.6 × 10²² cm^-3 ) and tiered nature of its anionic electrons, which offers guidance toward new catalysts.

Local flow structure of turbulence in three, four, and five dimensions

Probability density functions (PDF's) of the eigenvalues of the strain tensor of an incompressible isotropic turbulence in 3, 4, and 5 dimensions are computed by direct numerical simulation of Navier-Stokes equations. The PDF's of the smallest (negative) eigenvalue are found to be wider than those of the other ones in all dimensions and to be very insensitive to the dimension. In any dimension, the eigenvalues other than the lowest one increase as the lowest one decreases, so that they tend to be positive for the large magnitude of the lowest eigenvalue. In such a situation the flow comes in along a single direction and comes out in the other directions, which is consistent with the dynamics of the Burgers turbulence in d dimensions. It is suggested that a driving motor of most intermittent turbulent structure is the compression along a single direction. For the velocity 2 form the conditional averages of the enstrophy and the total squared strain in three dimensions are computed as functions of the smallest eigenvalue and found to be monotonically increasing as the magnitude of the smallest eigenvalue increases. Also, it is found that PDF of the source term of the Poisson equation for the pressure is positively skewed but tends to be symmetric with increase of the spatial dimension. Dimension effects on the dynamics of the most compressible eigenvalue are argued.

Hepatosplenic gamma delta T-cell lymphoma associated with hepatitis B virus infection

Hepatitis B virus (HBV) infection has been implicated in the development of hepatocellular and hematopoietic malignancies. We describe a patient with chronic hepatitis B who developed hepatosplenic gamma delta T-cell lymphoma. A 45-year-old woman presented with marked hepatosplenomegaly and hepatic failure during the course of chronic hepatitis B. Peripheral blood examination revealed 57% abnormal lymphoid cells which expressed the gamma delta T-cell receptor. The cytogenetic analysis of tumor cells showed an abnormal karyotype; 47, XX, -13, +2mar in all 20 metaphases examined. A clonal rearrangement of the T-cell receptor genes was demonstrated by Southern blot analysis, showing monoclonal expansion of tumor cells. A liver biopsy specimen showed fibrosis of the portal areas and sinusoidal infiltration of tumor cells. HBV infection was documented by the presence of IgG anti-HBc and anti-HBs antibodies in serum. Although HBV-DNA was not detected in tumor cells by polymerase chain reaction analysis, there is a possibility that proliferation of gamma delta T cells in response to HBV infection played a role in the pathogenesis of hepatosplenic gamma delta T-cell lymphoma.

Rounded atelectasis shown by computerized tomography

We have reported a rounded atelectasis in a 65-year-old man. On CT scan a pleural-based mass was associated with curved, ragged projections from the lower pole of the lesion. This phenomenon appears to be the counterpart of the so-called comet tail on regular tomography and, because of its clarity, may further facilitate the diagnosis of this entity.

Acute lymphoblastic leukemia following myelodysplastic syndrome

A 58-year-old man presented with anemia and neutropenia. The bone marrow examinations showed changes consistent with myelodysplastic syndrome. Twenty months later, acute lymphoblastic leukemia developed. This case appears to represent myelodysplastic (preleukemic) syndrome terminating in acute lymphoblastic leukemia.

Sudden death from pericardial tamponade. Unusual complication of nonbacterial thrombotic endocarditis

A ruptured myocardial infarct secondary to total coronary occlusion by a fragment of nonbacterial thrombotic endocarditis produced sudden, unexpected death in a nearly asymptomatic 82-year-old man who harbored two malignant neoplasms.

Metastasis of bronchogenic carcinoma to the skin involved by melanoma

In a 52-year-old man, a cutaneous malignant melanoma developed concurrently with an adenocarcinoma of the right lung. The latter disseminated widely, and autopsy disclosed that it had also metastasized to the dermal tissue involved with the melanoma. Because it was not a metastasis into the substance of the melanoma, it was classified as an unusual type of "collision tumor" rather than a "cancer-to-cancer" metastasis.

Malignant fibrous histiocytoma arising in previous surgical sites. Report of two cases

Two patients who developed malignant fibrous histiocytoma in previous surgical sites are reported. One patient developed malignant fibrous histiocytoma in an amputation site, and the other patient developed it in a previous hernioplasty scar. Both patients presented with a mass, clinically interpreted as a subcutaneous abscess. The light microscopic and fine structural features of these tumors are described. A possible causal relationship between previous surgery and malignant fibrous histiocytoma is discussed in view of other reported cases arising in various conditions following chronic reparative reactions.

Malignant fibrous histiocytoma arising in previous surgical sites. Report of two cases

Two patients who developed malignant fibrous histiocytoma in previous surgical sites are reported. One patient developed malignant fibrous histiocytoma in an amputation site, and the other patient developed it in a previous hernioplasty scar. Both patients presented with a mass, clinically interpreted as a subcutaneous abscess. The light microscopic and fine structural features of these tumors are described. A possible causal relationship between previous surgery and malignant fibrous histiocytoma is discussed in view of other reported cases arising in various conditions following chronic reparative reactions.

Esophageal metastasis from a peripheral lung carcinoma masquerading as a primary esophageal tumor

A 65-year-old man presented with progressive dysphagia, which proved to be the first clinical manifestation of a peripheral lung carcinoma (secondary to a submucosal metastasis in the esophagus). The lung tumor, hidden by the diaphragm on chest x-ray, was not suspected until a thoracotomy was done. Although dysphagia is known to be the first manifestation of bronchogenic carcinomas, such presentation in a case of a peripheral lung carcinoma has not been well described. This case is reported with a review of the literature for cases with dysphagia secondary to a metastatic tumor in the esophagus.

Artifactual hydropic degeneration in skin biopsy specimens immersed in saline: a light and electron microscopic study

An artifact, consisting of hydropic degeneration of the basal cells and subepidermal bulla formation, is described in skin-punch biopsy specimens immersed in normal saline. The histologic appearance and ultrastructural features of this artifact are discussed. Proper handling of skin specimens intended for immunofluorescent studies is stressed. Similarities are noted between the histologic and ultrastructural findings of this artifact and of epidermolysis bullosa simplex and pathologic hydropic degeneration, as is seen in lupus erythematosus.

Blastomycosis presenting with prostatic involvement: report of 2 cases and review of the literature

We report on 2 patients who presented with prostatic involvement as the first prominent clinical manifestation of systemic blastomycosis. The clinical symptoms of both patients began with dysuria and urinary retention. In 1 patient skin lesions developed 4 weeks later and the initial chest x-ray findings were positive. The other patient became aware of skin lesions concurrently with the urinary symptoms and had negative chest x-ray findings. Successful treatment consisted of amphotericin B in 1 case and ketoconazole in the other case. A review of the literature revealed 8 well documented cases of blastomycosis with the initial presenting symptom of prostatic involvement. A summary of the previously reported cases is presented and the importance of recognition of skin lesions in such patients is stressed.

Cytologically malignant squamous-cell carcinoma arising in a verrucous carcinoma of the penis

A case of verrucous carcinoma with a focus of cytologically malignant squamous-cell carcinoma is presented. This usually occurs following radiation therapy of the verrucous carcinoma, but may rarely occur de novo, as in this case. The potential usefulness of fine-needle aspiration in detecting focal anaplasia in verrucous carcinoma is discussed. This technique may be especially useful if the lesion is to be destroyed cryosurgically.

Fluorescence of melanoma cells. A useful diagnostic tool

Fluorescence seen in unstained sections from formalin-fixed, paraffin-embedded tissue from cases of malignant melanoma was studied. Fourteen of 16 primary cutaneous melanomas and six of eight metastatic melanomas were positive for yellow-green fluorescence. Four of 15 nevocellular nevi were also positive. Various other cutaneous tumors examined were completely negative. This fluorescence, which can be easily demonstrated, may be used as a valuable ancillary diagnostic test for differentiating melanoma cells from other cutaneous tumor cells.

Imbalance of T-cell subpopulations does not result in defective helper function in chronic lymphocytic leukemia

The T-lymphocyte subpopulations identified by the Fc receptors for IgG (TG cells) and IgM (TM cells) in 12 patients with B-cell chronic lymphocytic leukemia (CLL) were quantitated and studied for functional capabilities in an in vitro assay. The TG cells in patients were elevated in relation to age- and sex-matched normal controls (P less than 0.05) resulting in an altered TM/TG ratio of 1.8 +/- 0.76 in CLL versus 5.9 +/- 3.7 in controls (mean +/- SD, P less than 0.001). Despite this altered of B cells was found to be normal as reflected by the mean helper-suppressor score of 0.77 +/- 0.13 (+/- SEM) obtained for both patients and controls. This unimpaired capacity of the T cells from CLL patients to help normal B cells mature into immunoglobulin-secreting cells indicated that hypogammaglobulinemia and monoclonal serum immunoglobulins in these patients may be a result of either an intrinsic defect in the B lymphocytes or their replacement by a neoplastic clone rather than a defect in the immunoregulatory T cells.

Abnormalities of T lymphocyte subsets in patients with progressive systemic sclerosis (PSS, scleroderma)

Thirty-one patients with PSS (scleroderma) were examined for evidence of abnormalities in T lymphocyte subsets. TG and TM subpopulations of peripheral blood T lymphocytes were enumerated by rosetting techniques. The helper-suppressor functions of these lymphocytes were studied in the PWM-activated in vitro assay. The absolute numbers of TG cells in patients with DS as well as those with the CREST syndrome variant of PSS were decreased in comparison with those in age-matched healthy controls (p < 0.05). The numbers of TM and T "null" cells were not significantly altered (p > 0.05). The reduction in the number of TG cells was not caused by lymphocytotoxic antibodies. The mean helper-suppressor scores for patients with PSS and DS (1.25) and those with CREST syndrome (1.36) were higher (p < 0.05) than the mean score for healthy individuals (0.80). No relationship between the immunoregulatory abnormality and the presence or titer of CICs, ANAs, hypergammaglobulinemia, or various clinical manifestations of PSS could be demonstrated in individual patients. The finding of abnormalities in T lymphocyte subpopulations and the demonstration of their altered functional expression in patients with PSS indicate that immunoregulatory mechanisms may play an important role in this connective tissue disease.