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Graphite-like BC2 has yet to be synthesized; however, it stably exists in the Sc2B1.1C3.2 compound, where the boron atoms are arranged as far apart from each other as possible. Recently, a theoretical study on monolayer BC2 reported that in the most stable structure, B atoms are positioned adjacent to each other. We anticipated that graphite-like BC2 might take a different structure based on the electric charge. Therefore, we carried out first principles calculations to investigate whether this is true or not. The most stable structure among the six possible structures changed with the increase in the negative electric charge, which well explained both the previous results without contradiction. The most stable structure was also dependent on the pressure. The Li intercalation potential for BC2 was calculated to investigate its applicability as an anode for lithium-ion batteries. Our results revealed that Li atoms can be intercalated into BC2 to yield Li1.5BC2, whose gravimetric capacity is approximately 3.1 times higher than that of LiC6. However, the most stable structure with intercalated Li atoms became unstable when all the Li atoms were extracted. This feature may hinder the repetitive charge–discharge cycle of the anode and hence needs to be carefully considered.

The ternary borocarbide Sc2B1.1C3.2 is known to have a layered structure in which graphite-like BC2 layers and NaCl-like Sc2C layers are alternately stacked. Due to the complexity of the structure, X-ray analysis is unable to determine the precise structure of the BC2 layer, namely, how the boron atoms are arranged in the layer. Furthermore, the stacking manner of the two layers remains unclear. In this study, we have investigated the entire structure of Sc2B1.1C3.2 through first-principles calculations. The calculations reveal that the material is the most stable when B atoms are arranged to form 3 × 3 –R30° superlattices in the graphite-like layer. The interlayer bonding is mostly van der Waals-like, and the total energy is almost independent of the stacking method. The BC2 layer with the 3 × 3 –R30° structure can be regarded as an intermediate between similar graphite-like materials, BC and BC3. The electronic density of states of Sc2B1.1C3.2 exhibits metallic features, and electrons are transferred from Sc to B and C atoms, which compensates the lack of electrons in the BC2 layer. The origin of the undulation in the BC2 layer is not the inner electronic structure but the interaction between the BC2 and Sc2C layers. The weak localization found in the in-plane resistivity in experiments is explained by the domain boundaries of the 3 × 3 –R30° structure rather than the randomness of the arrangement of B atoms.

The impact of oral capecitabine as adjuvant chemotherapy for Japanese patients with resected colon cancer was unclear. We previously planned and conducted a prospective feasibility study (KSCC0803) and reported on the safety of oral capecitabine as adjuvant chemotherapy for Japanese patients with resected stage III colon cancer. The purpose of the current study was to assess the survival results from that study. The study subjects were Japanese patients with resected stage III colon cancer. The protocol adjuvant regimen consisted of oral capecitabine 1250 mg/m2 twice daily on days 1–14 of a 3-week cycle for a total of eight cycles. The 3- and 5-year disease free survival (DFS) rates and overall survival (OS) rates were analyzed in the eligible cohort. Ninety-seven patients were registered between September 2008 and August 2009 and treated with the protocol regimen. The median follow-up time was 60.7 months. The 3- and 5-year DFS rates were 71.2% [95% confidence interval (CI): 61.7–79.8%] and 69.7% (95% CI: 59.4–77.8%), respectively. The 3- and 5-year OS rates were 92.6% (95% CI: 85.2–96.4%) and 84.5% (95% CI: 75.1–90.5%), respectively. The survival results in this study are in line with those of previously reported, reliable, studies. The safety and tolerability of the protocol regimen have already been confirmed. Oral capecitabine is acceptable as adjuvant chemotherapy for Japanese patients with resected stage III colon cancer.

Mixed carcinoma of the pancreas is defined as the concurrent existence of pancreatic ductal carcinoma, acinar cell carcinoma, and/or islet cell carcinoma within the same neoplasm. We herein report a rare case of mixed ductal-acinar cell carcinoma in a 74-year-old man who was undergoing treatment for hypertension and diabetes at another hospital. After an abrupt worsening of his blood glucose control, the patient was referred to our hospital for further evaluation. Abdominal contrast-enhanced computed tomography and magnetic resonance imaging revealed a tumor with a multilocular cystic lesion in the head of the pancreas. Endoscopic retrograde cholangiopancreatography revealed obstruction of the main pancreatic duct and dilation of the dorsal pancreatic duct; in addition, adenocarcinoma was detected in the pancreatic juice cytology. Based on the abovementioned findings, the patient was diagnosed with carcinoma of the pancreatic head and underwent subtotal stomach-preserving pancreaticoduodenectomy. Based on the histopathological and immunohistochemical findings, the patient was diagnosed with mixed ductal-acinar cell carcinoma. The patient was prescribed TS-1 as postoperative adjuvant chemotherapy upon discharge. However, treatment was discontinued 2 months later due to marked general malaise, and the patient succumbed to tumor recurrence in the residual pancreas 12 months after the surgery.

We report a case of endocrine cell carcinoma (ECC) of the esophagus with long term survival after chemoradiotherapy. The patient had a complete response and remains without any recurrence. A 69-year-old woman visited our hospital because of progressive dysphagia. The patient was diagnosed by computed tomography and histology examination of biopsy specimens with small cell ECC of the esophagus, cT2N1M0, cStage II based on the Classification of Esophageal Carcinoma. She was treated with chemoradiotherapy comprising 45Gy of irradiation and four courses of cisplatin and etoposide chemotherapy. After completion of the treatment, she was found to have a complete response. She remains alive to date without evidence of any recurrence after 7 years. This case suggests that chemoradiotherapy is an effective treatment for ECC of the esophagus.

It is still controversial whether patients with a history of gastrectomy have high risk of esophageal carcinogenesis. On the other hand, the treatment strategy for esophageal cancer patients after gastrectomy is complicated. The association between histories of gastrectomy and esophageal carcinogenesis was retrospectively analyzed, and the treatment of esophageal cancer patients after gastrectomy was evaluated based on questionnaire data collected from multiple centers in Kyushu, Japan. The initial subject population comprised 205 esophageal cancer patients after gastrectomy. Among them, 108 patients underwent curative surgical treatment, and 70 patients underwent chemoradiation therapy (CRT). The time between gastrectomy and esophageal cancer development was longer in peptic ulcer patients (28.3 years) than in gastric cancer patients (9.6 years). There were no differences in the location of esophageal cancer according to the gastrectomy reconstruction method. There were no significant differences in the clinical background characteristics between patients with and without a history of gastrectomy. Among the 108 patients in the surgery group, the 5-year overall survival rates for stages I (n = 30), II (n = 18), and III (n = 60) were 68.2%, 62.9%, and 32.1%, respectively. In the CRT group, the 5-year overall survival rate of stage I (n = 29) was 82.6%, but there were no 5-year survivors in other stages. The 5-year overall survival rate of patients with CR (n = 33) or salvage surgery (n = 10) was 61.2% or 36%, respectively. For the treatment of gastrectomized esophageal cancer patients, surgery or CRT is recommended for stage I, and surgery with or without adjuvant therapy is the main central treatment in advanced stages, with surgery for stage II, neoadjuvant therapy + surgery for stage III, and CRT + salvage surgery for any stage, if the patient's condition permits.

This review discusses the ternary borocarbide Sc2B1.1C3.2 and graphite-like (g-) BC2. Sc2B1.1C3.2 has a layered structure in which two types of layers, graphene-like BC2 and MXene-like Sc2C, are stacked alternately; hence, Sc2B1.1C3.2 can be regarded as a graphene-MXene complex compound. The X-ray diffraction structural analysis was ambiguous due to the close atomic numbers of B and C; however, the most stable structure determined by first-principles calculations had B atoms in the BC2 layer arranged in a √ 3 × √ 3 –R30° superlattice which was an intermediate between the already known BC3 and BC structures. Bulk g-BC2 has also been studied for potential application as the anode of Li-ion batteries. Calculation of the intercalation potential revealed that Li atoms can be intercalated into BC2 to yield Li1.5BC2, which has a specific capacity approximately 3.1 times that of graphite (LiC6).

In this work we report the results of our investigation of YbB66 as a potential high-temperature thermoelectric material. A high-quality single crystal has been grown by the optical floating zone method. Thermoelectric transport properties were measured in a temperature range of 373–973 K YbB66, like REB66 compounds in general, is a p-type semiconductor whose electrical properties can be described by Mott's variable range hopping mechanism. It shows very large Seebeck coefficient ranging from 588 μV K−1 at 373 K to 241 μV K−1 at 973 K and an electrical resistivity ρ that decreases by almost 4 orders of magnitude from 9.4×10−1 Ω m to 2.4 × 10−4 Ω m. Together with the low thermal conductivity of 2.6 W m−1 K−1 a maximum ZT close to 0.1 around 1000 K was determined with trend of sharp increase toward higher temperatures, which is similar to the previous report of SmB66, and significantly larger than previously reported for Y and Er phases of REB66. However, unlike SmB66, the effective magnetic moment suggests a trivalent state for Yb instead of mixed valence, which was determined by measuring the magnetic susceptibility from 2 to 300 K. The composition of YbB66 was indicated to be metal-rich, which actually may be the origin of the good performance.

AIM This study aimed to clarify the predictive impact of visceral fat on response to bevacizumab in patients with metastatic colorectal cancer (mCRC). PATIENTS AND METHODS Pretreatment computed tomography was used to measure visceral fat area (VFA) and patients with mCRC receiving first-line chemotherapy with/without bevacizumab were divided by median VFA value into two groups: high VFA and low VFA. RESULTS In the bevacizumab-treated group, patients with low VFA had significantly shorter overall survival (OS) than patients with high VFA in univariate (median=21.1 vs. 38.9 months; hazard ratio=1.70, 95% confidence interval=1.06-2.70, p=0.03) and multivariate analysis (hazard ratio=1.85, 95% confidence interval=1.15-3.03, p=0.01). No significant differences were seen in OS between groups treated with chemotherapy alone. The VFA had a marginally significant modifying effect on the relationship between bevacizumab and OS (p for interaction=0.07). CONCLUSION Our findings provide the first evidence that a low VFA might be a negative predictive marker for response to bevacizumab in patients with mCRC.

The purpose of this phase II study was to explore the efficacy and safety of an alternating regimen consisting of folinic acid, 5-fluorouracil (5-FU) and oxaliplatin (mFOLFOX6) plus bevacizumab, and folinic acid, 5-FU and irinotecan (FOLFIRI) plus bevacizumab as first-line treatment for patients with metastatic colorectal cancer. Fifty-two patients with metastatic colorectal cancer received an alternating regimen consisting of four cycles of mFOLFOX6 plus bevacizumab followed by four cycles of FOLFIRI plus bevacizumab until disease progression. The primary endpoint was progression-free survival. The median age was 60 years (range 37–75 years). Median progression-free survival was 14.2 months (95 % confidence interval [CI] 10.6–16.3) and median overall survival was 28.4 months (95 % CI 22.6–39.1). The overall response rate was 60.0 % (95 % CI 45.2–73.6). Regarding toxicity, the commonest grade 3–4 hematological adverse events were neutropenia (34.6 %) and leukopenia (7.7 %), and the commonest grade 3–4 non-hematological adverse events were anorexia (13.5 %), fatigue (9.6 %), nausea (9.6 %), and vomiting (9.6 %). Bevacizumab-related grade 3–4 adverse events included hypertension (1.9 %) and thrombosis (1.9 %). An alternating regimen consisting of mFOLFOX6 plus bevacizumab and FOLFIRI plus bevacizumab is an effective and well-tolerated first-line chemotherapy combination for patients with metastatic colorectal cancer.

The melting behavior of s-boron at the boron-rich side of the B–C binary phase diagram is a long standing question whether eutectic or peritectic. Floating zone experiments have been employed to determine the melting type on a series of C-containing feed-rods prepared by powder metallurgy and sinter techniques. Melting point data as a function of carbon-content clearly yielded a peritectic reaction isotherm: L+B 4+ δ C=(sB). The partition coefficient of carbon is ~2.6. The experimental melting point data were used to improve the existing thermodynamic modeling of the system B–C. Relative to the thermodynamically accepted melting point of pure sB ( T M =2075 °C), the calculated reaction isotherm is determined at 2100.6 °C, a peritectic point at 0.75 at% C and a maximum solid solubility of 1.43 at% C in (sB) at reaction temperature. With the new melting data the refractory system Hf–B–C has been recalculated and the liquidus surface is presented. The influence of the melting behavior of (sB) on the phase reactions in the B-rich corner of M–B–C diagrams will be discussed and demonstrated in case of the Ti–B–C system.

Anti-epidermal growth factor receptor antibody therapy alone or in combination with irinotecan is recognized as a standard third-line treatment for KRAS wild-type unresectable metastatic colorectal cancer. However, in some cases, it is difficult to administer irinotecan after third-line treatment. Therefore, we examined the efficacy and safety of the combination of cetuximab and S-1 in patients with KRAS wild-type unresectable metastatic colorectal cancer who were previously treated with irinotecan, oxaliplatin, and fluoropyrimidines.The study was designed as a phase II, non-randomized, open-label, multicenter trial. Cetuximab was initially administered at 400 mg/m(2), followed by weekly infusion at 250 mg/m(2). S-1 was administered at a fixed dose of 80 mg/m(2) orally twice daily for 28 days followed by a 14-day break, resulting in a 6-week treatment course. The primary endpoint was progression-free survival (PFS). The secondary endpoints were the overall response rate (ORR), overall survival (OS), disease control rate (DCR), time to treatment failure, dose intensity, safety, and BRAF mutation status.Thirty-seven patients were eligible. The median PFS was 5.5 months, the median OS was 13.5 months, the ORR was 29.7 %, and the DCR was 73.0 %. The relative dose intensity was 86.8 % for cetuximab and 88.1 % for S-1. Grade 3-4 adverse events that occurred in10 % of the patient population included rash, dry skin, diarrhea, paronychia, anorexia, fatigue, mucositis, and neutropenia.Combination therapy with cetuximab and S-1 was effective and well tolerated in patients with irinotecan-, oxaliplatin-, and fluoropyrimidine-refractory metastatic colorectal cancer.

Reflux esophagitis (RE) is a known complication disturbing patients' quality of life after esophageal resection. It is generally recognized that bile reflux as well as acid reflux cause RE. However, the clinical influence of acid and bile reflux, and Helicobacter pylori (H. pylori) infection on RE in the cervical esophagus after esophagectomy is not yet clarified. Sixty patients who underwent cervical esophagogastrostomy following esophagectomy were enrolled in this study. They underwent examination for H. pylori infection, endoscopic examination, and continuous 24-hour pH and bilirubin monitoring, at 1 month after surgery. The influence of acid and/or bile reflux, H. pylori infection, and others on the development of RE were investigated. RE was observed in 19 patients (32%) at 1 month after esophagogastrostomy, mild RE in 16 (27%), and severe RE in 3 (5%). The percentage of time duration of both acid and bile reflux into the cervical esophagus was higher in patients with RE than in those without (P = 0.027, P 0.14 between non-RE and mild RE (P = 0.017). Acid and/or bile reflux was observed in 31 patients (52%), acid-only reflux in 6 (10%), bile-only reflux in 15 (25%), and acid-and-bile reflux in 10 (17%). Severe RE was observed only in patients having acid-and-bile reflux. On the univariate analysis, no infection of H. pylori, acid reflux, and bile reflux were determined to be the influencing factors to RE among the clinical factors including age, gender, route of esophageal reconstruction, H. pylori infection, and acid-and-bile reflux. In the subanalysis using the logistic model, there were significant correlations between bile reflux and RE irrespective of the presence of H. pylori infection (P = 0.016, P = 0.007). On the other hand, there was a significant correlation between acid reflux and RE only in patients without H. pylori infection (P = 0.039). In the early period after esophagogastrostomy, bile reflux could cause RE irrespective of H. pylori infection, while acid reflex could cause RE only in patients without H. pylori infection. There is a possibility that bile reflux plays an important role in the development of RE after esophagectomy.

Aortic complications after esophageal cancer surgery are rare and usually fatal. Here, we report three patients who underwent thoracic endovascular aortic repair (TEVAR) for aortic complications after esophagectomy for cancer. In the first case, aortic rupture was caused by pyothorax due to residual tumor after esophagectomy. In the second case, aortic rupture was caused by pyothorax due to anastomotic leakage. In the third case, a pseudoaneurysm was caused by surgical injury during esophagectomy. TEVAR was safe and effective for severe aortic complications when graft infection was avoided. The first case died of sepsis on the 84th postoperative day, and the other two cases have survived 4 years and 2 years to date.

The aim of this study was to determine the factors influencing acidity in the gastric conduit after esophagectomy for cancer. Acidity and bile reflux in the stomach and in the gastric conduit were examined by 24-h pH monitoring and bilimetry in 40 patients who underwent transthoracic subtotal esophagectomy followed by esophageal reconstruction using a gastric conduit, which was pulled up to the neck through a posterior mediastinal route in 17 patients, through a retrosternal route in 10 patients, and through a subcutaneous route in 13 patients. They were examined at 1 week before surgery, at 1 month after surgery, and at 1 year after surgery. Helicobacter pylori infection was examined pathologically and using the (13) C-urea breath test. The factors influencing acidity of the gastric conduit were analyzed using the stepwise regression model. Gastric acidity assessed by percentage (%) time of pH 0.14 into the lower portion of the gastric conduit was significantly increased after surgery throughout the period from 1 month after surgery to 1 year after surgery. Multivariate analysis showed that the acidity in the gastric conduit was influenced by H. pylori infection and DGR at 1 month after surgery, and by H. pylori infection and the route for esophageal reconstruction at 1 year after surgery. Acidity in the gastric conduit was significantly decreased after surgery. Acidity in the gastric conduit for esophageal substitutes is influenced by H. pylori infection and surgery. DGR influences the gastric acidity in the short-term after surgery, but not in the long-term after surgery.

The The luminescence spectra of B 4.3 C, B 6.5 C and B 10 C boron carbide with different isotope enrichments ( 10 B, 11 B, 12 C, 13 C) yield electron transition energies from gap states into the valence band and between localized levels in the gap with 0.25 meV resolution. The results well agree with the actual band scheme derived from optical absorption, electrical properties and interband luminescence. Within the whole homogeneity range, the transition energies are independent of chemical composition and isotopes.

The quality of life in patients who have undergone surgery for esophageal cancer is frequently disturbed by postoperative gastroesophageal reflux disease or pharyngolaryngeal reflux disease. Recently, there have been many reports on gastroesophageal reflux disease after esophagectomy, and only a few on pharyngolaryngeal reflux disease. There is not yet any convenient endoscopic classification of reflux pharyngolaryngitis. We designed a new classification for reflux pharyngolaryngitis based on endoscopic findings. Our new classification consists of the five grades from 0 to IV based on (i) the extent and severity of erythema and/or edema in the pharynx and the larynx, and (ii) the extent and severity of granulation or scarring stenosis in the vocal cords. Ninety-three patients after cervical esophagogastrostomy after esophagectomy (the CEG group) and 28 patients after intrathoracic esophagogastrostomy (the TEG group) were reviewed in this study. We investigated the relation between the severity of reflux pharyngolaryngitis and clinical symptoms in these patients, and the correlation between this new classification of reflux pharyngolaryngitis and the Los Angeles classification of reflux esophagitis. Reflux esophagitis was more severe in the TEG group than in the CEG group, while there was no difference in the grading of reflux pharyngolaryngitis between the two groups. The pharyngolaryngeal symptoms and F-scale scores were not correlated with the severity of reflux pharyngolaryngitis in each group. The grading of reflux pharyngolaryngitis and that of reflux esophagitis was correlated in each group (P

Using resonance ultrasound spectroscopy, we measured the monocrystal elastic-stiffness coefficients, the Voigt C ij, of TiB2. With hexagonal symmetry, TiB2 exhibits five independent C ij: C 11, C 33, C 44, C 12, C 13. Using Voigt-Reuss-Hill averaging, we converted these monocrystal values to quasiisotropic (polycrystal) elastic stiffnesses. Briefly, we comment on effects of voids. From the C ij, we calculated the Debye characteristic temperature, the Gruneisen parameter, and various sound velocities. Our study resolves the enormous differences between two previous reports of TiB2's C ij.

We have been investigating the high-temperature thermoelectric properties of some novel rare earth borides with a structure containing B12 icosahedra. Doping effects on the TE properties in such systems were investigated for the first time. A series of Nb-doped YB66 and C-doped YB66 single crystals were grown by the floating zone method. The Nb-doped compounds have approximate chemical formulas ranging from YNb0.30B66 to YNb0.33B66 while the C-doped compound has a formula of YB66C0.6. The effect of Nb-doping on the thermoelectric properties was not monotonic and appears to be complex. As a result of Nb-doping, the room temperature resistivity and the characteristic temperature T0 were considerably reduced. At room temperature the power factor of the Nb-doped YB66 sample with 89% site occupancy was three times greater than that of non-doped YB66. However, in the important high-temperature region, the non-doped sample actually exhibited the highest power factor for T > 550 K . Furthermore, owing to a structural feature of YB66, thermal conductivity actually increases with doping of transition metals. Taking into account all the thermoelectric properties, transition metal doping of YB66 is therefore not suitable for our purposes. On the other hand, doping of carbon, which is assumed not to go into the same sites as the transition metals, yielded a lowering of the thermal conductivity. Furthermore, contrary to Nb-doping, carbon doping did not result in a reversal of the relative magnitude of resistivity at extremely high temperatures and therefore, an increase in the figure of merit of factor 2 was realized at 1000 K.

The effect of transition metal doping in YB66 has been studied with respect to increase its thermal conductivity. Single crystals of YB66 doped with 4th, 5th and 6th group transition metals were grown by floating zone method. A detailed structure analysis suggested that an existing special B—B pair at the (1/4, 1/4, 1/4) site of YB66 could be attributed to a phonon scattering center that causes the amorphous-like low thermal conductivity. It was found that 5th and 6th group transition metals of V, Cr, Nb and Mo substitute the B—B pair. By contrast 4th group transition metals such as Ti and Zr were found to enter another (x, x, x) site with x ∼ 0.135. Thermal conductivity of both Nb-doped and undoped YB66 was measured in the range 4 K ≤ T ≤ 150 K. Nb doping increased thermal conductivity of YB66 with a factor of about 2.

Nb-doped YB 66 single crystals were grown by the floating-zone method using a 4 ellipsoidal mirror-type xenon lamp image furnace. Nb-doping is expected to improve the performance of YB 66 soft X-ray monochromators. Maximum site occupancy of Nb achieved was 95%. Full-width at half-maximum of the rocking curve measured for CuK α 10 0 0 reflection achieved 40–50 arcsec. Thermal conductivity of the crystal with the maximum site occupancy increased about two times that of undoped YB 66 crystals.

RMn2Si2 (R=La, Ce, Pr, Nd, Sm, Gd) single crystals were grown from high temperature lead metal flux by slowly cooling under an argon atmosphere. The RMn2Si2 (R=Ce, Pr, Nd, Sm, Gd) crystals were obtained as thin plates with well-developed {0 0 1} faces. The largest crystals have maximum dimensions of about 2.3 mm ×2.3 mm ×0.02 mm. LaMn2Si2 was generally obtained as powder of irregular shape. The as-grown RMn2Si2 (R=Ce, Pr, Nd, Sm, Gd) crystals were used for measurements of Vickers micro-hardness at room temperature, oxidation resistance heated in air, and magnetic susceptibility using a SQUID magnetometer at low temperatures. The values of the Vickers micro-hardness for the {0 0 1} faces of RMn2Si2 are in the range of 5.8±0.4 to 6.5±0.5 GPa. The oxidation process of crystals was studied at temperatures below 1473 K by TG–DTA analyses. The TG curves show that the oxidation of CeMn2Si2, PrMn2Si2, NdMn2Si2, SmMn2Si2, and GdMn2Si2 crystals starts at about 738, 979, 999, 784, and 763 K, respectively. Weight gains of the compounds after TG determination were measured to be in the range of 16.4–29.2 mass%. The results of the magnetic susceptibility measurements agree with recent previous work which has been done on these compounds.

Crystal growth of rare-earth boron-rich solids in RE-B-C(-N) and RE-B-Si systems from Cu and Si solutions has been studied. The grown crystals are RE x B 22 C 3−δ N δ ( x =0.6–0.8, 0≤δ≤1), RE x B 28.5 C 4 (RE=Y, Ho, Er, Tm, Lu), REB 25 C 5 (RE=Y, Tb) and RE x B 12 Si ∼3 ( x =0.65–0.7, RE=Y,Gd–Lu). The first two phases are built with interconnected boron icosahedra and octahedra, which are regarded as homologous phases of B 4 C. REB 25 C 5 is a superstructure of YAlB 14 -type YB 25 C and RE x B 12 Si ∼3 is a new structure type. The crystal growth conditions and crystallography are described in this paper.

Crystals of Sc 2 AlB 6 were grown using scandium oxide and elemental boron as starting materials in a self-component aluminum solution under an argon atmosphere. The growth conditions for obtaining single crystals of relatively large size were investigated. Sc 2 AlB 6 single crystals were obtained in the form of prisms extending in the b-axis direction. The largest Sc 2 AlB 6 crystals prepared had maximum dimensions of about 0.4 x 0.4 x 4.2 mm 3 . The values of the Vickers microhardness and the electrical resistivity of Sc 2 AlB 6 crystals are 12.7 ± 0.8 GPa and 43 ± 8 μΩcm, respectively. The oxidation of Sc 2 AlB 6 crystals starts at about 773°C, and the weight gain after TG determination is 12.9 mass% at 1200°C. The oxidation products of Sc 2 AlB 6 crystals could not determined.

A novel quaternary scandium borocarbosilicide Sc3.67−xB41.4−y−zC0.67+zSi0.33−w was found. Single crystallites were obtained as an intergrowth phase in the float-zoned single crystal of Sc0.83−xB10.0−yC0.17+ySi0.083−z that has a face-centered cubic crystal structure. Single crystal structure analysis revealed that the compound has a hexagonal structure with lattice constants a = b = 1.43055(8) nm and c = 2.37477(13) nm and space group P 6 m2 (No. 187). The crystal composition calculated from the structure analysis for the crystal with x = 0.52, y = 1.42, z = 1.17, and w = 0.02 was ScB12.3C0.58Si0.10 and that agreed rather well with the composition of ScB11.5C0.61Si0.04 measured by EPMA. In the crystal structure that is a new structure type of boron-rich borides, there are 79 structurally independent atomic sites, 69 boron and/or carbon sites, two silicon sites and eight scandium sites. Boron and carbon form seven structurally independent B12 icosahedra, one B9 polyhedron, one B10 polyhedron, one irregularly shaped B16 polyhedron in which only 10.7 boron atoms are available because of partial occupancies and 10 bridging sites. All polyhedron units and bridging site atoms interconnect each other forming a three-dimensional boron framework structure. Sc atoms reside in the open spaces in the boron framework structure.

Single crystals of REMn2Si2 (RE=Y, Tb, Dy, Ho) were grown from a high-temperature lead metal solution in an argon atmosphere. Single crystals of REMn2Si2 were obtained in the form of thin plates with well-developed (001) faces. The as-grown REMn2Si2 crystals were used for measurements of micro-Vickers hardness at room temperature, oxidation resistance in air and magnetic susceptibility at low temperatures. The values of the micro-Vickers hardness for the (001) faces of REMn2Si2 crystals are about 5.5 GPa. The oxidation process of REMn2Si2 crystals was studied at a temperature below 1473 K by TG-DTA analyses. The TG curves show that the oxidation of YMn2Si2, TbMn2Si2, DyMn2Si2 and HoMn2Si2 crystals starts at about 811, 807, 844, and 849 K, respectively. Weight gains of the compounds after TG determination were measured to be in the range of 14.7–19.7 mass%. The results of magnetic susceptibility measurements at low temperatures of the compounds are discussed.

Ytterbium borosilicide YbB 45.6 Si 1.0 crystals were successfully grown by the floating zone method. YbB 45.6 Si 1.0 takes the recently discovered YB 50 -type structure and has an orthorhombic structure with lattice constants of a =16.636(4) A, b =17.644(2) A, c =9.488(2) A. Other magnetic REB 50 -type compounds have been discovered to exhibit the first magnetic transitions found for B 12 icosahedral compounds. The physical properties of ytterbium borosilicide were investigated to observe whether anomalous behavior is observed for the ytterbium phase such as is the case in the REB 12 borides where YbB 12 is a Kondo insulator. The resistivity of YbB 45.6 Si 1.0 follows the 3D variable range hopping temperature dependence down to low temperatures. The existence of sizable magnetic anisotropy is indicated and anomalies are observed at low temperatures indicative of a magnetic transition of antiferromagnetic character with T N =5.5 K. This behavior is similar to that of the other magnetic REB 50 compounds. Information on the electronic ground state is also obtained, with the ground state of ytterbium borosilicide indicated to be a Kramer’s doublet.

The crystal structure of a novel quatenary compound Th2ScB6C3 was derived by combined Rietveld-Patterson methods from room temperature X-ray powder diffractometiy. Th2ScB6C3 crystallises with a unique structure type (space group P6/mmm) with a = 0.660296(7), c = 0.358421(4) nm. Metal atoms form a planar hexagonal net of thorium atoms centered by smaller scandium atoms. Non-metal atoms are found in planar Kagome nets 6B.(6B+3C)2 at z = 1/2. The non-metal layer corresponds to the one in the ThB2C-type and forms a link to the simple structure of the AlB2-type which has recently become the focus of intense interest due to discovery of superconductivity (Tc = 39 K) in MgB2. Physical properties (magnetization, specific heat, resistivity) of Th2ScB6C3 indicate metallic characteristics. Low temperature measurements reveal no evidence for a superconductive transition in this new quatenary compound. The magnetization of isostructural U2ScB6C3 is also investigated and a ferromagnetic transition is observed at Tc = 56 K.

A novel ternary boron-rich scandium borocarbide Sc 4.5− x B 57− y + z C 3.5− z ( x =0.27, y =1.1, z =0.2) was found. Single crystals were obtained by the floating zone method by adding a small amount of Si. Single-crystal structure analysis revealed that the compound has an orthorhombic structure with lattice constants of a =1.73040(6), b =1.60738(6) and c =1.44829(6) nm and space group Pbam (No. 55). The crystal composition ScB 13.3 C 0.78 Si 0.008 calculated from the structure analysis agreed with the measured composition of ScB 12.9 C 0.72 Si 0.004 . The orthorhombic crystal structure is a new structure type of boron-rich borides and there are six structurally independent B 12 icosahedra I1—I6, one B 8 /B 9 polyhedron and nine bridging sites all which interconnect each other to form a three-dimensional boron framework. The main structural feature of the boron framework structure can be understood as a layer structure where two kinds of boron icosahedron network layer L1 and L2 stack each other along the c -axis. There are seven structurally independent Sc sites in the open spaces between the boron icosahedron network layers.

Single crystals of REMn 2 Si 2 (RE=Er, Tm, Yb, Lu) were grown from a high-temperature lead metal flux in an Ar atmosphere. The REMn 2 Si 2 crystals were plates enclosed by large {0 0 1} faces, and small {1 0 0} and {1 0 1} faces; maximum crystal size was 2.5×2.5×0.02 mm 3 . Chemical analyses of the crystals show the chemical composition with atomic ratios RE (RE=Er, Tm, Yb, Lu):Mn:Si=1:2:2. The values of the micro-Vickers hardness for the {0 0 1} faces of ErMn 2 Si 2 , TmMn 2 Si 2 , YbMn 2 Si 2 and LuMn 2 Si 2 are 5.0±0.4, 6.3±0.3, 7.9±0.3 and 6.1±0.4 GPa, respectively. According to thermogravimetric and differential thermal analyses, the oxidation of ErMn 2 Si 2 , TmMn 2 Si 2 , YbMn 2 Si 2 and LuMn 2 Si 2 crystals began to proceed at about 778, 978, 987, and 974 K, respectively. The results of magnetic susceptibility measurements down to low temperatures of the compounds are discussed.

Single crystals of REMn2Si2 (RE=Y, Tb, Dy, Ho) were grown from a high-temperature lead metal flux by slowly cooling the melt in an argon atmosphere. The REMn2Si2 crystals were obtained as thin plates with well-developed (001) faces, and the largest crystals have maximum dimensions of about 2.6×2.6×0.02 mm3. The as-grown REMn2Si2 crystals were used for chemical analyses, measurements of unit cell parameters and magnetic susceptibility at low temperatures. The results of magnetic susceptibility measurements of the crystals are discussed.

The boron-rich solid of YB 25 can incorporate certain amounts of carbon atoms. With increase of carbon content, two kinds of superstructures of YB 25 , which modulate the basic structure in the (001) plane, appeared. The framework of boron icosahedra in the superstructures remains the same as that of YB 25 and the structural modulation is just caused by the variation of carbon distribution in the voids of the framework. In addition, one superstructure with a large unit cell is quenchable and transformed into another superstructure by thermal annealing at 1400°C for 80 h.

Single crystals of a novel boron-rich scandium borocarbosilicide Sc0.83−xB10.0−yC0.17+ySi0.083−z were grown by the floating zone method using a four-xenon lamp mirror-type image furnace. Structure analysis using single-crystal X-ray diffraction data showed that Sc0.83−xB10.0−yC0.17+ySi0.083−z has a face-centered cubic with lattice constant a=2.03085 nm and space group of F 4 3m. The crystal composition calculated from the structure analysis was ScB12.0C0.65Si0.071 which agreed with the measured composition of ScB12.7C0.62Si0.08. In the crystal structure which is a new structure type of boron-rich borides, there are three structurally independent B12 icosahedra I(1), I(2) and I(3) and one B10 polyhedron which interconnect each other to form a three-dimensional boron framework. There are four fully occupied bridging sites, one is the C site and the other three sites are occupied statistically by B or C. The Sc atoms reside in three interstitial sites of the boron framework. Two Si sites are tetrahedrally surrounded by the bridging carbon sites and by the bridging boron/carbon mixed occupation sites, respectively. The boron framework structure can be understood more easily by introducing larger structure units, they are a super tetrahedra T(1) made up by four icosahedra I(1), a super tetrahedra T(2) made up by four icosahedra I(2) and a super octahedra O(1) made up by six icosahedra I(3).

The gadolinium phase of the YB 50 structure-type compounds was successfully obtained for the first time. In the case of the REB 50 compounds, which were recently discovered, the rare-earth atom series smaller than gadolinium (terbium Tb to lutethium Lu) were found to form compounds. This system is interesting, because it displays the first magnetic transition ever observed in the B 12 borides. There is a high incentive to synthesize the gadolinium phase of these compounds, because the mechanism of the transition is not completely clear, and data available up to now have shown that the Curie-Weiss temperatures roughly follow a dependence on the deGennes factor. By adding silicon, we were successful in synthesizing gadolinium borosilicide GdB 41 Si 1.2 , which is isostructural to YB 50 . Magnetic susceptibility measurements show that the Curie-Weiss temperature of GdB 41 Si 1.2 is −7.2 K and lower than the terbium borosilicide analog, thus showing a deviation from the deGennes factor dependence. Although a sizable paramagnetic tail obscured the behavior of the low temperature susceptibility, measurement of the specific heat of GdB 41 Si 1.2 revealed a peak, unambiguously indicating a magnetic transition with a transition temperature of 4 K.

New rare-earth boron-rich solids of the composition REB 28.5 C 4 (Re=Y, Ho, Er, Tm and Lu) were synthesized by solid state reaction and single crystals were grown using a high temperature metal solution method. The structure was solved by a direct method from single crystal X-ray diffraction data with Y–B–C as a representative. It shows a layered structure with trigonal symmetry (space group: R 3 m (No. 166)) and the unit cell parameters are: a = b =5.6457(9) A, c =56.8873(13) A.

Single crystals of a novel ScB19 family compound ScB19+xSiy were grown by the floating zone method using a four-lamp mirror-type image furnace. A small amount of silicon addition to ScB19 which decomposes at elevated temperatures without melting allowed it to coexist with the liquid phase and as a resultant made the floating zone crystal growth possible. Powder X-ray diffraction analysis confirmed the grown crystals of ScB19+xSiy to be isostructural to ScB19. It was found that the crystal structure of ScB19+xSiy solved based on single-crystal X-ray data is tetragonal with lattice constants of a, b=1.03081(2) nm, c=1.42589(3) nm, space group P41212 or P43212 and is basically isotypic with α-AlB12 structure type. In the crystal structure boron atoms form a three-dimensional framework based on interconnected B12 icosahedra and B22 polyhedra. The Sc atoms reside in three of five Al sites in the α-AlB12 structure and Si resides in a bridge site bonding two B22 units.

The crystal structure of a layered compound Sc2B1.1C3.2, scandium boride carbide (M r = 140.43), has been re-refined as a commensurate composite crystal using 1795 single-crystal X-ray diffraction intensities with I > 2\sigma(I) collected by Shi, Leithe-Jasper, Bourgeois, Bando & Tanaka [(1999), J. Solid State Chem. 148, 442–449]. The crystal is composed of two layered subsystem structures, i.e. Sc—C—Sc sandwiches and graphite-like layers of the composition B1/3C2/3. The structure refinement was performed in a five-dimensional formalism based on the trigonal superspace group P\bar{3}m1(p00)(0p0)0m0. The unit cell and other crystal data are a = b = 3.387 (1), c = 6.703 (2) Å, V = 66.59 (1) Å3, \boldsigma_{1} = (9/7 0 0), \boldsigma_{2} = (0 9/7 0), Z = 1, D x = 3.501 Mg m−1. Two different three-dimensional sections through the superspace were analyzed, corresponding to two different superstructure models, one with P\bar{3}m1 and the other with P\bar{3}m1. A random distribution of B and C was assumed in the graphite-like layer and 41 structural parameters were introduced. R F /wR F } were 0.0533/0.0482 and 0.0524/0.0476, respectively, for the first and second models. Although the difference between these R F or wR F values was too fine to exclude one of the models definitely, the advantages of using a superspace group were obvious. It not only brought about better convergence of refinement cycles by virtue of fewer parameters, but also gave an insight into the problem of symmetry of the superstructure.

A new series of boron-rich solids ReB{sub 22}C{sub 2}N (Re: Y, Ho, Er, Tm, Lu) was synthesized by traditional solid-state reaction. The crystal structure of the representative compound YB{sub 22}C{sub 2}N was solved by direct method from powder X-ray diffraction (XRD) data and transmission electron microscope (TEM) analysis. The unit cell of the new structure is rhombohedral with space group R-3m (No. 166), lattice constant a = b = 5.623(0) {angstrom} and c = 44.785(3) {angstrom} with six formula units in one unit cell. The atoms of boron in the solids, like most of the boron-rich solids, exist with icosahedral and octahedral clusters, and the whole crystal shows a layered structure. The interconnected nine layers of icosahedron and three layers of octahedron in a unit cell build the whole framework of the new phase and rare earth metal atoms reside in voids of the octahedron layers. The neighboring icosahedral layers link through C-B-C chains besides the direct bonding of B-B. Both experimental and structural analysis indicated that the nitrogen atoms in the new phase can be replaced with carbon.

Binary REB25 (RE = Gd, Tb, Dy, Ho, Er) B12 icosahedral compounds were successfully synthesized and magnetic properties were measured. Measurements down to 1.8 K revealed that an antiferromagnetic-like transition occurs in TbB25 at 2.1 K. This transition temperature is almost one order of magnitude lower than that of the transition in the more magnetically dilute TbB50. The structure of TbB25 is refined and, from the differences of structure, the previous conclusion that B12 icosahedra are indicated to play an important role in the transition of TbB50 is further supported. The other magnetic rare-earth compounds show Curie-Weiss behaviour down to the lowest temperatures, with values of the effective moment close to that expected for trivalent rare-earth compounds.

The crystal structure of a new layered compound Sc2B1.1C3.2 has been refined based on a five-dimensional formalism using single crystal X-ray diffraction data. RF was 0.043 for 1398 reflections with I>4σ(I) using 41 structural parameters on a commensurate composite crystal model. The generator set of symmetry operations of the trigonal superspace group employed are x, y, z, u, v; -y, x-y, z, -v, u-v; y, x, -z, v, u; -x, -y, -z, -u, -v. The unit cell and other crystal data are a=b= 3.387(1), c=6.703(2)a, σ1=(9/7 0 0), σ2=(0 9/7 0), Z=1, Dx=3.501 Mg/mm3.

回腸-結腸型腸重積症を呈した重積内腸管に単純性小腸潰瘍が存在し,穿通・瘻孔を形成したため腸閉塞の腸管内減圧が得られ,閉塞症状の改善をきたしたと推察される1例を経験した.症例は59歳女性で,腹痛,食思低下の初発症状より約1カ月間自宅にて放置され,嘔吐,全身浮腫,意識レベルの低下をきたし当院へ搬送された.全身管理のもと諸検査施行し成人腸重積症の診断下に外科的手術を行った.術後摘出標本所見,病理組織学的所見および臨床経過より単純性小腸潰瘍および瘻孔の存在する腸重積症と診断した.腸重積症と小腸潰瘍との合併例,また腸重積腸管内での穿通,瘻孔形成をきたした報告例はわれわれの検索しえた限りではなく,極めて稀な症例と思われるので報告した.

Atomic positions for Y atoms were determined by using high-resolution electron microscopy and electron diffraction. A slow-scan charge-coupled device camera which had high linearity and electron sensitivity was used to record high-resolution images and electron diffraction patterns digitally. Crystallographic image processing was applied for image analysis, which provided more accurate, averaged Y atom positions. In addition, atomic disordering positions in YB56 were detected from the differential images between observed and simulated images based on x-ray data, which were B24 clusters around the Y-holes. The present work indicates that the structure analysis combined with digital high-resolution electron microscopy, electron diffraction, and differential images is useful for the evaluation of atomic positions and disordering in the boron-based crystals.

Boron K -edge inelastic X-ray scattering experiments were performed on clean B 4 C and shock impact recovered boron carbide up to 30 GPa and at ambient temperature to understand the pressure induced bonding changes. The spectral features corresponding to the boron site in the interlinking chain remained unchanged up to 30 GPa. The results of our experiments indicate that pressure induces less distortion to the boron sites and the local amorphization observed in the previous reports are due to the rearrangement of carbon atoms under extreme conditions without affecting the boron environment.