Observation of 2D-magnesium-intercalated gallium nitride superlattices.

Since the demonstration of p-type gallium nitride (GaN) through doping with substitutional magnesium (Mg) atoms1,2, rapid and comprehensive developments, such as blue light-emitting diodes, have considerably shaped our modern lives and contributed to a more carbon-neutral society3-5. However, the details of the interplay between GaN and Mg have remained largely unknown6-11. Here we observe that Mg-intercalated GaN superlattices can form spontaneously by annealing a metallic Mg film on GaN at atmospheric pressure. To our knowledge, this marks the first instance of a two-dimensional metal intercalated into a bulk semiconductor, with each Mg monolayer being intricately inserted between several monolayers of hexagonal GaN. Characterized as an interstitial intercalation, this process induces substantial uniaxial compressive strain perpendicular to the interstitial layers. Consequently, the GaN layers in the Mg-intercalated GaN superlattices exhibit an exceptional elastic strain exceeding -10% (equivalent to a stress of more than 20 GPa), among the highest recorded for thin-film materials12. The strain alters the electronic band structure and greatly enhances hole transport along the compression direction. Furthermore, the Mg sheets induce a unique periodic transition in GaN polarity, generating polarization-field-induced net charges. These characteristics offer fresh insights into semiconductor doping and conductivity enhancement, as well as into elastic strain engineering of nanomaterials and metal-semiconductor superlattices13.

THz Gas Sensing Using Terahertz Time-Domain Spectroscopy with Ceramic Architecture.

Ceramic architectures based on chemical vapor deposition (CVD) are used to create unique crystal structures, morphologies, and properties. This study proposed room-temperature THz gas sensing using terahertz time-domain spectroscopy (THz-TDS) with ceramic architectures. We synthesized ceramic films on porous glass. Zinc oxide films were created using atmospheric CVD and amorphous carbon nitride films using the dissociative excitation reaction of BrCN with metastable Ar atoms. The transmission method was used in THz-TDS. A stainless hand-made gas cell with a Si window was applied for THz gas sensing. We defined "phase delay" equals VOC sensing response amount of sensing materials at each duration. Ppm-order THz gas sensing was performed.

Terahertz time-domain ellipsometry with high precision for the evaluation of GaN crystals with carrier densities up to 1020 cm-3.

Gallium nitride (GaN) is one of the most technologically important semiconductors and a fundamental component in many optoelectronic and power devices. Low-resistivity GaN wafers are in demand and actively being developed to improve the performance of vertical GaN power devices necessary for high-voltage and high-frequency applications. For the development of GaN devices, nondestructive characterization of electrical properties particularly for carrier densities in the order of 1019 cm-3 or higher is highly favorable. In this study, we investigated GaN single crystals with different carrier densities of up to 1020 cm-3 using THz time-domain ellipsometry in reflection configuration. The p- and s-polarized THz waves reflected off the GaN samples are measured and then corrected based on the analysis of multiple waveforms measured with a rotating analyzer. We show that performing such analysis leads to a ten times higher precision than by merely measuring the polarization components. As a result, the carrier density and mobility parameters can be unambiguously determined even at high conductivities.

Lymphovascular invasion predicts poor prognosis in high-grade pT1 bladder cancer patients who underwent transurethral resection in one piece.

BACKGROUND: Lymphovascular invasion (LVI) in high-grade clinical T1 bladder cancer is usually considered a poor prognostic factor, but it is often difficult to achieve correct staging of T1 bladder cancer and diagnose the presence of LVI because of the inadequacy of conventional transurethral resection specimens. The aims of this study were to evaluate the prognostic value of LVI in patients with correctly staged high-grade pathological T1 (pT1) bladder cancer who initially underwent transurethral resection in one piece (TURBO). METHODS: Eighty-six high-grade pT1 bladder cancer patients who underwent TURBO were enrolled. Risk of tumor understaging was avoided by examining the vertical resection margin of the TURBO specimen. Immunohistochemical staining using D2-40 and CD31 was performed to confirm LVI. We examined the association of LVI with other clinicopathological factors and the impact of LVI on progression-free survival and cancer-specific survival. RESULTS: The median follow-up period was 49 months (range, 6-142). In all patients, the tumors were accurately staged as pT1 at initial TURBO. LVI was detected in 15 patients (17%) and was significantly associated with tumor growth pattern (P = 0.001). Multivariate analysis identified LVI as the only independent predictor for reduced progression-free survival (HR, 4.48; 95% CI, 1.45-13.90; P = 0.009) and cancer-specific survival (HR, 4.35; 95% CI, 1.17-16.24; P = 0.029). CONCLUSIONS: The presence of LVI in TURBO specimens independently predicts poor clinical outcomes in patients with high-grade pT1 bladder cancer. This information may help urologists to counsel their patients when deciding whether to choose a bladder-preserving strategy or radical cystectomy.

Acute acalculous cholecystitis due to breast cancer metastasis to the cystic duct.

BACKGROUND: Acute acalculous cholecystitis (AAC) is a relatively rare disorder of the gallbladder. Breast cancer recurrence more than 10 years after curative surgery is also infrequent. CASE PRESENTATION: Here, we report a case of a 59-year-old woman who presented with right flank pain. Her medical history included a lumpectomy for cancer of the left breast 12 years prior. Laboratory tests showed a severe inflammatory reaction and mild liver function abnormalities. Ultrasonography and computed tomography revealed an enlarged gallbladder and inflammation of the surrounding tissues; however, no gallstone was present. She was diagnosed with AAC. We performed an emergency laparoscopic cholecystectomy, and histopathological examination revealed a poorly differentiated adenocarcinoma in the cystic duct. Both metastatic and primary tumor cells were positive for estrogen and progesterone receptors on immunohistochemistry. The final pathological diagnosis was acute cholecystitis due to breast cancer metastasis to the cystic duct. CONCLUSION: Although AAC secondary to metastatic breast cancer is rare, it should be included in the differential diagnosis for abdominal pain in patients with a previous history of breast cancer.

A Low-Grade Fibromyxoid Sarcoma of the Internal Abdominal Oblique Muscle.

A low-grade fibromyxoid sarcoma (LGFMS) is a rare tumor, with a benign histologic appearance but malignant behavior. This report describes a 74-year-old man with an internal abdominal oblique muscle mass. The tumor appeared as a well-defined ovoid mass on computed tomography, with mild uptake on fluorine-18-fluorodeoxyglucose positron-emission tomography images. Radical resection with wide safe margins was performed. Histologically, the tumor was composed of spindle-shaped cells in a whorled growth pattern, with alternating fibrous and myxoid stroma. MUC4 expression, a highly sensitive and specific immunohistochemical marker for LGFMS, was detected. Therefore, we diagnosed the tumor as LGFMS. At the 3-month follow-up, there was no sign of recurrence or metastasis. We report the first case of LGFMS arising from the internal abdominal oblique muscle.

Clinicopathologic analysis of 6 lymphomatoid gastropathy cases: expanding the disease spectrum to CD4-CD8+ cases.

Lymphomatoid gastropathy, which was first reported in 2010, is a rare NK-cell proliferation of cyCD3, CD4, CD5, CD8, CD56 phenotypes with unknown etiology. The diagnosis is challenging, as there is histopathologic similarity to malignant lymphoma. In the 2010 report on 10 cases, all lesions were located in the stomach, and all regressed without any therapy. In the present study, we analyzed 6 cases of lymphomatoid gastropathy by investigating the clinicopathologic, immunohistochemical, and molecular findings. Endoscopic and morphologic appearances of all cases were consistent with previous reports, but 2 cases showed previously unreported unique immunophenotypes of CD4CD8. Three of 6 patients underwent lower gastrointestinal examination (1 case underwent double-balloon endoscopic examination), but no patient had lesions in the lower gastrointestinal tract. No obvious difference of histology was found between the cases of CD4-CD8-typical phenotype and ones of CD4CD8 phenotype. Both cases had similar clinical behavior as the other 4 cases, implying that the spectrum of the disease is broader than initially thought. Careful clinical and endoscopic follow-up is required for the diagnosis of lymphomatoid gastropathy, and additional case studies and molecular studies are warranted to further investigate the pathophysiology of this peculiar benign mimic of lymphoma.

Clinicopathologic analysis of IgG4-related skin disease.

IgG4-related disease is a recently recognized systemic syndrome characterized by mass-forming lesions with lymphoplasmacytic infiltration, increase in the number of IgG4(+) cells in affected tissues and elevation of serum IgG4 levels. In 2009, we were the first to report skin lesions in patients with IgG4-related disease, but no large case series has been reported and clinicopathological findings remain unclear. To clarify these features, we herein report 10 patients (9 men and 1 woman; median age, 64 years; age range, 46-81 years) with IgG4-related skin disease. All patients had erythematous and itchy plaques or subcutaneous nodules on the skin of the head and neck, particularly in the periauricular, cheek, and mandible regions, except for one patient, whose forearm and waist skin were affected. In addition, eight patients had extracutaneous lesions: these were found on the lymph nodes in six patients, the lacrimal glands in three patients, the parotid glands in three patients, and the kidney in one patient. Histologically examined extracutaneous lesions were consistent with IgG4-related disease; five of six lymph node lesions showed progressively transformed germinal centers-type IgG4-related lymphadenopathy. Cases of IgG4-related skin disease were classified into two histological patterns: those exhibiting a nodular dermatitis pattern and those with a subcutaneous nodule pattern. The infiltrate was rich in plasma cells, small lymphocytes, and eosinophils; the majority of the plasma cells were IgG4(+). The IgG4(+) cell count was 49-396 per high-power field (mean±s.d., 172±129), with an IgG4(+)/IgG(+) cell ratio ranging from 62 to 92%. Serum IgG4 levels were elevated in all examined patients. In conclusion, patients with IgG4-related skin disease had uniform clinicopathology. Lesions were frequently present on the skin of the periauricular, cheek, and mandible regions, and were frequently accompanied by IgG4-related lymphadenopathy.