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In this study, cysteine-containing dipeptides conjugated with amino acids possessing mono- and diamino-groups were developed as protein-folding modulators affording non-native forms through intermolecular disulfide-bond formation.

To examine the diagnostic usefulness and procedures of ultrasonography (US) for mass lesions in the soft tissue of the oral region.This study involved patients with mass lesions (tumorous lesions and cysts) who had undergone US and histopathological examinations from January 2017 to December 2019. The following points were evaluated by two observers using an evaluation scale: vascularity, echo intensity level, boundary, margin shape, distribution of internal echoes, and capsule. The usefulness of each point for differential diagnosis of tumorous lesions and cysts was statistically analyzed.Forty-five mass lesions in the soft tissue of the oral region (33 tumorous lesions and 12 cysts) were analyzed. There were significant differences in four evaluation points between the tumorous lesions and cysts: vascularity, echo intensity level, boundary, and margin shape. Cysts were almost completely excluded diagnostically, especially when vascularity was observed. There were also significant differences in two evaluation points between nonvascular tumorous lesions and cysts: echo intensity level and boundary.In US examination for mass lesions in the oral region, it was possible to diagnose tumorous lesions and exclude cysts when vascularity was observed. When vascularity was not observed, however, tumorous lesions and cysts could be identified using two evaluation points: echo intensity level and boundary.

Immune checkpoint inhibitors (ICIs) targeting programmed death ligand-1 (PD-L1) are highly promising therapies for oral squamous cell carcinoma (OSCC). The assessment of PD-L1 expression may help predicting the therapeutic effect of ICIs and, thus, benefit patient selection. Contrast index (CI) parameters derived from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) have been proven as efficient to assess microvessel density (MVD) in OSCC. The present study aimed to determine the correlation between DCE-MRI parameters and MVD and between DCE-MRI parameters and PD-L1 expression to determine whether DCE-MRI could be used non-invasively to evaluate PD-L1 expression in patients with OSCC. A total of 21 patients with primary OSCC who had undergone a 3T MRI scan, including DCE-MRI, were included in the present study, and CI curve-derived parameters were examined. The MVD and PD-L1 expression in the surgically resected specimens were analyzed using immunohistochemistry (IHC) staining for CD31 and IHC staining for PD-L1, respectively. The results demonstrated that the expression levels of these markers were correlated with DCE-MRI parameters. PD-L1 expression levels were found to be significantly correlated with the maximum CI (CI-max; P=0.007), peak CI (CI-peak; P=0.007), maximum CI gain (CI-gain; P=0.006) and MVD (P=0.001) values. The mean CI-max, CI-peak, CI-gain and MVD values were significantly higher in tumors with high PD-L1 expression (P

Purpose The prevalence of supernumerary teeth has been reported to be between 0.1% and 3.8%. The aim of this study was to determine the prevalence, clinical significance, and associated pathologies of fourth molars based on a retrospective study and a literature review. Materials and Methods A 5-year retrospective prevalence study was conducted at the Department of Oral Diagnosis and Dentomaxillofacial Radiology of Okayama University Hospital, Okayama, Japan. The study involved extracting data from the digital records of patients from January 1, 2013 through December 31, 2017. The sampling frame included all patients who had panoramic radiographs, cone-beam computed tomography (CT), and multislice CT images during the period under review. Results A total of 26,721 cases were reviewed and 87 fourth molars were identified. The prevalence of fourth molars in the 5-year study at Okayama was calculated as 0.32%. The mean age of patients with a fourth molar was 30.43 years, and the male-to-female ratio was 1:0.98. The vast majority of cases were in the maxilla (92%) and had normal shapes (89.7%); furthermore, 82.8% of cases were unerupted. Conclusion The prevalence of fourth molars in the study population was found to be 0.32%, and fourth molars occurred with approximately equal frequency in males and females. Fourth molars were more common in the maxilla and were predominantly unerupted and small.

Crosslinkers play essential role in determining physical properties of gels. Using cray substance, Laponite (Rockwood Additive Ltd, USA), as the crosslinker, we made N-isopropylacrylamide(NIPA) gels. We found, if we count one Laponite crystal as one crosslinker, that NIPA gels crosslinked with Laponite gelled at much lower fraction (1/2000) of crosslinker than the gel crosslinked with popular N,N'-methylenebisacrylamide(BIS). This result indicates that Laponite is extremely multifunctional crosslinker. Though the volume changes of the NIPA-Laponite gels were continuous one, the volume change itself was much larger than that of the NIPA-Bis gels, and we observed the hysteresis loop as well as the miner loops just like magnetic system. We will discuss about the possible mechanism of such hysteresis loops.

Objectives: The purpose of this study was to evaluate the usefulness of Hounsfield unit (HU) assessment with multislice-CT in the differentiation of radicular cysts (RCs), dentigerous cysts (DCs) and odontogenic keratocysts (OKCs). Methods: In total, 307 odontogenic cysts (RCs, DCs and OKCs) were included in this study. Cysts with lesion diameter Results: In total, 164 cysts were analysed in this study (64 RCs, 57 DCs and 43 OKCs). Regardless of the type of lesion, the Aquilion ONE scanner demonstrated a significant difference in HU value, compared with the Discovery CT750 HD scanner. Regardless of CT scanner model, HU values significantly differed between DCs and OKCs (p < 0.0001), as well as between OKCs and RCs (p < 0.0001). Conclusions: HU values were found to vary among CT scanners and should always be associated with other lesion imaging features while interpreting and elaboration diagnostic hypothesis. Notably, the results suggested that OKCs might be able to be differentiated from DCs and RCs by using HU values.

The numbers of abnormal findings incidentally detected in adjacent regions are increasing with advances in imaging modalities. The present study aimed to examine the prevalence and characteristics of incidental findings in the thyroid gland on computed tomography (CT) images of the oral and maxillofacial region. CT scans of the oral and maxillofacial region in patients obtained between January 2012 and December 2016 were retrospectively reviewed. Images that revealed incidental findings in the thyroid gland, including nodules, were recorded, together with the sizes and characteristics of the findings. The Japan Association of Breast and Thyroid Sonology (JABTS) guidelines were used for classification. The rate of descriptions of these findings in the radiographic interpretation reports were also examined. Of the 1,135 patients examined, 326 (28.7%) had several types of incidental findings. In particular, 169 (14.9%) of the 1,135 patients had nodules >5 mm in diameter, for which further careful examination is recommended in the JABTS guideline. The description rate for nodules >5 mm in diameter in the radiographic interpretation reports was 30.8% (52/169 patients), of whom 17.3% (9/52 patients) were referred to the endocrinology department for further careful examination. Incidental findings in the thyroid gland were relatively common on CT images of the oral and maxillofacial region. Oral radiologists tend to focus specifically on the oral and maxillofacial region during diagnosis on oral and maxillofacial CT images, but should pay the same careful attention to observe adjacent regions, such as the thyroid gland.

Oxidative protein folding is a biological process to obtain a native conformation of a protein through disulfide-bond formation between cysteine residues. In a cell, disulfide-catalysts such as protein disulfide isomerase promote the oxidative protein folding. Inspired by the active sites of the disulfide-catalysts, synthetic redox-active thiol compounds have been developed, which have shown significant promotion of the folding processes. In our previous study, coupling effects of a thiol group and guanidyl unit on the folding promotion were reported. Herein, we investigated the influences of a spacer between the thiol group and guanidyl unit. A conjugate between thiol and guanidyl units with a diethylene glycol spacer (GdnDEG-SH) showed lower folding promotion effect compared to the thiol–guanidyl conjugate without the spacer (GdnSH). Lower acidity and a more reductive property of the thiol group of GdnDEG-SH compared to those of GdnSH likely resulted in the reduced efficiency of the folding promotion. Thus, the spacer between the thiol and guanidyl groups is critical for the promotion of oxidative protein folding.

We documented the current status of the macrobenthic community of Lake Nojiri (surface area: 4.56 km2; maximum depth: 38.5 m; altitude: 654 m above sea level; mesotrophic lake), and examined changes over time in the densities of chironomids and oligochaetes, by comparison with previous quantitative data of the lake reported in 1931 and 1973. We discussed the succession of benthic macroinvertebrates in relation to changes in the lake bottom environment, as evidence of lake eutrophication. On March 10, 2015, a bathymetrical sampling survey was carried out using a standard Ekman grab at each of the 5 stations (min. ca. 6 m – max. ca. 27 m) in Lake Nojiri. The average densities of the benthic communities for all the stations were ca. 5000m-2, comprised principally of oligochaetes ca. 2800 m-2 (57%) and chironomids ca. 2100 m-2 (43%), whereas their benthic biomass averaged ca. 9.7 g m-2, chironomids ca. 7.6 g m-2 (77%) and oligochaetes ca. 2.3 g m-2 (23%). In the shallower stations, the dominant species was Heterotrissocladius sp., but Chironomus nipponensis Tokunaga was the dominant species in the deeper stations. The densities of C. nipponensis was ca. 14 times higher than those reported by Miyadi in 1931 and 4 times higher than reported by Kitagawa in 1973a. In recent years the density of the oligochaete Tubifex tubifex, has tended to increase and the anoxic- and anaerobic-layer have thickened, especially in deeper regions where they are widely distributed. Moreover, we found differences in the C. nipponensis larval growth rate with water depth, i.e., small IV-instar larvae that dominated at the deepest Station 5. At this station, we suggest that low dissolved oxygen concentration and low water temperature during summer-fall suppresses growth of C. nipponensis. Large environmental changes must have affected chironomid and oligochaete densities and growth rate of C. nipponensis, especially in the deeper regions with low dissolved oxygen concentrations, low water temperature and high organic matter (ignition loss; 15.0% in St. 4 and 13.9% in St. 5) in the sediments. This is a strong evidence that the eutrophication of this lake is continuing., Article, JOURNAL OF LIMNOLOGY.77(1):81-87(2018)

For high reliability non-volatile memory cell dielectrics, hydrogen-free deuterated charge-trap SiN and tunnel SiON films are demonstrated. By using deuterated ammonia instead of ammonia as nitridation species in ALD cycles, an ultra-high deuterium/hydrogen ratio has been successfully obtained in both films, and these films showed good endurance for program / erase stress and data retention properties in MONOS capacitors.

Selective area growth of GaN (SAG-GaN) films grown on nonpolar m-plane bulk GaN substrates using trench patterns was performed by metalorganic vapor phase epitaxy. We investigated the transformation of SAG-GaN facet structures by changing growth temperature, ambient, and miscut angle of substrates. Substrates with trench patterns along a -axis formed (10-11), (10-10), and (000-1) facet structures after SAG-GaN growth for growth conditions of 800 °C in N 2 +NH 3 and 1000 °C in H 2 +NH 3 ambience. Those with trench pattern along 45° off from a -axis contained (11-22), (10-10), (0-110) facet structures in substrates with a miscut angle of 5° whereas SAG-GaN films completely coalesced and formed smooth (10-10) surface in substrates with a miscut angle of 1°. Undesirable grains were formed for 800 °C in N 2 +NH 3 ambience regardless of the miscut angle of substrates whereas theses grains were annihilated using 1000 °C in H 2 +NH 3 ambience due to the intensively hydrogen etching.

Coupling of thiol and urea-type -NHC([double bond, length as m-dash]X)NH2 (X = O or NH) groups is effective in promoting oxidative protein folding. In particular, a thiol compound coupled with a guanidyl (X = NH) group significantly accelerates the rates of folding processes and enhances the yields of native proteins.

An electrostatic time-of-flight detector named E-MCP has been developed for quick diagnostics of circulating beam and timing measurement in mass spectrometry at the Rare-RI Ring in RIKEN. The E-MCP detector consists of a conversion foil, potential grids, and a microchannel plate. Secondary electrons are released from the surface of the foil when a heavy ion hits it. The electrons are accelerated and deflected by 90$^\circ$ toward the microchannel plate by electrostatic potentials. A thin carbon foil and a thin aluminum-coated mylar foil were used as conversion foils. We obtained time resolutions of 69(1) ps and 43(1) ps (standard deviation) for a $^{84}$Kr beam at an energy of 170 MeV/u when using the carbon and the aluminum-coated mylar foils, respectively. A detection efficiency of approximately 90% was obtained for both foils. The E-MCP detector equipped with the carbon foil was installed inside the Rare-RI Ring to confirm particle circulation within a demonstration experiment on mass measurements of nuclei around $^{78}$Ge produced by in-flight fission of uranium beam at the RI Beam Factory in RIKEN. Periodic time signals from circulating ions were clearly observed. Revolution times for $^{78}$Ge, $^{77}$Ga, and $^{76}$Zn were obtained. The results confirmed successful circulation of the short-lived nuclei inside the Rare-RI Ring.

Adenoid cystic carcinoma (ACC) is a rare epithelial tumor of the head and neck region, and one of the most common malignant tumors of the salivary glands. ACC is a slow-growing tumor characterized by perineural invasion and often has a high-recurrence rate. We describe a case of oropharyngeal ACC invading the mandibular bone through the mandibular foramen that showed a rare pattern of origin and invasion. A 70-year-old woman complained of noise and pain around the right temporomandibular joint. Osteomyelitis was suspected on the initial imaging examinations, although the findings were slightly atypical. However, a mass was observed in the right oropharyngeal wall on subsequent imaging examinations, and mandibular bone invasion, rather than osteomyelitis, was additionally suspected. The mass in the right oropharyngeal wall and right mandible was surgically excised. On postoperative histopathological examination, the mass was finally diagnosed as ACC. As tumor cells were also observed around the inferior alveolar nerve, mandibular bone invasion through the mandibular foramen was suspected. An oropharyngeal ACC invading the mandibular bone through the mandibular foramen is extremely rare. The present case suggests that bone invasion should be considered carefully with several imaging examinations when a malignant tumor such as ACC is observed around the jaw bone.

The number of significant incidental findings identified on radiographic examinations has increased. In total, 169 patients, 87 males and 82 females, with a mean age of 67.3 years (range, 17-92 years), as well as 65 patients (38.5%), 43 (66.2%) female and 22 (33.8%) male had abnormal findings in the thyroid for one year in our institution. Thyroid nodules are the most common incidental findings on oral and maxillofacial evaluations. Computed tomography (CT) and magnetic resonance imaging (MRI) examination are frequently used to detect thyroid abnormality. The present study reported a case of papillary thyroid carcinoma (PTC) detected following CT and MRI examination of a mandibular lesion. The CT examination of the oral and maxillofacial region included the thyroid, which must be examined carefully to detect various diseases, including PTC. Collaboration between radiologists and clinicians is important to manage these incidental findings.

It is known that the magnetic resonance (MR) imaging features of dentigerous cysts (DCs) are the same as those of other cysts. The cavities of DCs generally show low signal intensity (SI) on T1-weighted imaging (T1WI). However, in our experience, DCs often show high SI on T1WI, rendering them difficult to distinguish from keratocystic odontogenic tumors (KCOTs). In this study, we evaluated seven cases of DC and 23 cases of KCOT to assess whether MR imaging can provide additional information for the differential diagnosis of DC and KCOT. Two trials were evaluated. The first trial was an analysis of the cystic cavity SI on T1WI. To compare the SI between patients, we performed T1WI with contrast (T1c). The second trial analyzed the SI uniformity (U Σ) on T1WI, T2-weighted imaging (T2WI), and short inversion time inversion recovery (STIR) images of the cystic cavity, because it has been reported that an MR imaging feature of KCOT is heterogeneous SI. Statistical analyses were performed using the Mann–Whitney U test and a receiver operating characteristic (ROC) curve. The T1c values of DCs were significantly higher than those for KCOTs. The U Σ values on T1WI and STIR images were significantly higher for DCs than for KCOTs. The T1c cutoff values (0.66 and 0.84) and U Σ cutoff values for T1WI (82.1 %) and STIR images (79.8 %) were determined from the ROC analyses. T1c and U Σ values provide useful additional information for the differential diagnosis of DC and KCOT.

Two kinds of different malignant tumors occurring within the same organ is defined as collision tumor. Small Cell Carcinoma (SmCC) is high-grade derived from neuroendocrine cell tumors, occurance in the head and neck is rare. Squamous Cell Carcinoma (SCC) is the most common malignancies encountered in head and neck area, but the occuranceof collision tumor is very rare. This report describe a 82 year-old woman patient with a SmCC and SCC that occurred in the maxillary sinus. CT was performed including with enhancement, MRI examination was T1WI, STIR and contrast enhancement. We also conducted analysis of Dynamic Contrast Enhancement (DCE). Histopathologic examination revealed small cell carcinoma. A distant metastasis was not detected. After patient received chemoradiotherapy (CCRT), most of tumorwas reduced although a part of the tumor was remained. Pathological examination of surgery tumor specimen revealed that specimen consisted of SCC and SmCC was disappeared, and six months after surgery, the patient suffered tumor recurrence and multiple metastasis to the organs in the abdomen. This time we have to report that the experience one cases that are considered collision cancer of SmCC and SCC that occurred in the maxillary sinus.

OBJECTIVES: To investigate the correlations among various temporomandibular joint (TMJ) findings on MRI and the relationships between MRI findings and symptoms. METHODS: 425 patients (850 TMJs) with temporomandibular joint disorders (TMDs) who underwent MRI were enrolled. Oblique sagittal proton density-weighted and T (2) weighted images in open- and closed-mouth positions were evaluated. MRI findings included disc configuration, disc position, condylar morphology, bone marrow pattern, and joint effusion. Symptoms included TMJ pain, TMJ noise, and limitation of mouth opening. For statistical analyses, Spearman's rank correlation coefficient and logistic regression analysis were applied. RESULTS: Folded disc, disc displacement without reduction (DDWOR), and osteophytes had significant negative correlations with other normal MRI findings (p < 0.01). DDWOR and marrow edema were associated with TMJ pain. Conversely, osteophytes [odds ratio (OR): 0.52; 95% CI (0.30–0.90)] and combination-type condylar degeneration [OR: 0.45; 95% CI (0.24–0.83)] were associated with decreased risk of TMJ pain. Condylar flattening was positively associated with TMJ noise [OR: 5.25; 95% CI (1.44–19.07)] and negatively associated with limitation of mouth opening [OR: 0.34; 95% CI (0.11–0.99)]. High-grade joint effusion was significantly associated with TMJ pain and noise. CONCLUSIONS: DDWOR and high-grade joint effusion (an indicator of inflammation in the articular cavity) were associated with TMD symptoms. This finding suggests that treatment strategy for DDWOR and decreasing inflammation might lessen clinical TMD symptoms. Condylar degeneration was not associated with indicators of inflammation or TMJ symptoms. These results suggest that patients with TMD symptoms should undergo initial MRI to allow rapid selection of appropriate therapies.

This paper describes the navigation and the guidance strategy of the small spacecraft for flyby using the images of the target small body. We derived navigation and guidance accuracies of this mission analytically, and confirmed them by numerical simulations. For high accurate flyby, the center of the target needs to be measured accurately. However the shade area on the target surface makes it difficult to know the target center position from the information of the center of brightness on image. This uncertainty caused the guidance error. To resolve this problem, this paper proposes a method to calculate the target center from the tangent points of the sun light. The validity of the method is examined in the experiment.

The selective-area growth of GaN (SAG-GaN) films on nonpolar bulk GaN substrates with trench patterns was performed by metalorganic vapor phase epitaxy. We investigated the transformation of SAG-GaN facet structures by changing the direction of the trench patterns. Anisotropic SAG-GaN structures with the () facet on the (0001) plane sidewall, the () facet on the top surface, and the () facet on the () plane sidewall appeared for trench patterns along the a-axis. The width of () facets decreased whereas () facets expanded with increasing off angle of trench patterns from the a-axis. On the other hand, hexagonal facet structures with {} facets appeared for trench patterns along the c-axis. () facets on the top surface expanded with increasing off angle of trench patterns from the c-axis, similar to the results of using trench patterns along the a-axis. Basal-plane stacking faults were annihilated by using trench-patterned substrates. Low basal-plane stacking fault (BSF) density and faster coalescence were obtained for the off angle of trench patterns of around 6° from the c-axis.

LSAT (La0.3Sr0.7)(Al0.65Ta0.35)O3, which has a complex perovskite structure of (A'A'')(B'B'')O3, is expected as an attracting substrates for GaN and high temperature superconductivity oxides solid thin films from a viewpoint of the suitable lattice matching. To grow high quality thin film, it is very important to prepare step-terrace structure on substrates used for thin film growth. For this purpose, a technique of annealing substrates with mirror surface is often used. However, surface precipitates, called surface mounts, are reported to appear after annealing LSAT substrates [1]. In this study, we investigated the surface precipitates formed on annealed LSAT surfaces by TEM/STEM. Further, we directly confirmed the terminated atomic layers at the annealed LSAT surfaces in the area without surface precipitates.Commercially available LSAT single crystal substrates with (001) surfaces (SHINKOSHA CO.,LTD) were used for TEM/STEM observation. After annealing at 1300°C for 30 min in air, the (001) surface structures were observed from [110] direction using cross sectional thin foils. The thin foils were prepared by joining two annealed LSAT (001) surfaces with glue, grinding, polishing and finally Ar ion milling. TEM/STEM observation was conducted by JEOL ARM-200F (a double Cs-corrector type for TEM/STEM) operated at 200kV.Surface mounds were confirmed to appear on LSAT crystal surface after annealing at the annealing condition used in this study. A typical example is shown in Fig. 1. shows TEM bright field image taken from the surface area of LSAT (001) after annealing. The observation direction of the image is [110], which is parallel to the annealed surface. Cross sectional images of surface mounts with 300nm was clearly seen as indicated by the arrows in the image. The height of the mounts is around 20nm, and it is noted that the interfaces between the mounts and LSAT surfaces are hollowed into LSAT crystal with the depth about 10nm. Nano diffractometric and EDS analysis have revealed that the mounts are amorphous structure with mainly Al and Sr. So far, the surface mounts has been considered to be SrO precipitation because the mounts easily dissolve into water. After cleaning in water, smooth surfaces for thin film growth can be considered to be obtained. However, the mounts are revealed to be formed on the hollowed surfaces of LAST as shown in Fig. 1. To use LSAT annealed surfaces as suitable substrates for thin film growth, the hollowed surface structure should be considered.jmicro;63/suppl_1/i20/DFU049F1F1DFU049F1Fig. 1.TEM bright field image of surface mounds on LSAT (001) annealed surface. Meanwhile, we determined the terminated atomic layers of the surface by carrying out high resolved HAADF-STEM observation at the areas without the mounts. After annealing, the surfaces without any mounts have atomically flat (001) surface structure at an atomic level. To clarify the terminated atomic layers, it must be necessary to assign a position of a unit cell for atomically resolved HAADF-STEM image. To carry out the assignment, we used an ordered domain structure exiting in LSAT crystal [2]. In the ordered domains, the cations of Al and Ta occupy at B-site periodically. Observing the B-site ordered domains by HAADF-STEM, the respective B-site atomic columns can be distinguished separately with contrast difference due to the atomic number of Al and Ta ions. To use the contrast variation, we can precisely assign the unit cell position for the obtained HAADF-STEM image. As a result, it was found that the annealed surfaces were terminated at B-site at the area without any mounts. Further, EDS analysis has revealed that Al/Ta ratio at terminated B-site layer is different from that of crystals, which is Al/Ta ∼ 1. There is a report informing that La ions tend to vapor during annealing LSAT [1]. The formation of the surface mounts is closely related to the vaporization of La ions near surfaces. The mounts was formed from residual ions of Al and Sr. As a result, the surface areas without any mounts can be considered to include Ta more.

One of the most important success for the theory of nucleosynthesis is the precise reproduction of the mass abundance ration for helium-4 as 25% during the Big Bang. This achievement can be one of the three proves of the existence of the Big Bang. For the comparisons between the theory and the observations, abundances of deutron and helium-3 are also consistent. However, there is a quite large inconsistency for litium-7 where the theoretical result is three times higher than the observations, which are reported by Sipte[1] and Asplund[2]. In order to solve this hard inconsistency we may refine data base of the nuclear reaction information around the Li. Despite the many previous efforts there could still be a region where the experimental information is not sufficient between 0.1 and 0.4 MeV of the c.m. energy[3,4]. Consequently, we have started the experimental study with measuring the astrophysical s-factor for the destruction of Li.

One of the most prominent success with the Big Bang models is the precise reproduction of mass abundance ratio for 4He. In spite of the success, abundances of lithium isotopes are still inconsistent between observations and their calculated results, which is known as lithium abundance problem. Since the calculations were based on the experimental reaction data together with theoretical estimations, more precise experimental measurements may improve the knowledge of the Big Bang nucleosynthesis. As one of the destruction process of lithium-7, we have performed measurements for the reaction cross sections of the 7L(3He,p)9Be reaction.

The thermal stability of GaN surfaces was investigated with respect to homo-epitaxy on free-standing GaN substrates. Morphologies and etching rates of the GaN surfaces for free-standing polar (0001), nonpolar , and semipolar and planes were studied before and after thermal cleaning. In the case of the polar (0001) plane, polishing scratches disappeared after thermal cleaning at temperatures above 1000 °C. The surface morphology depended on not only the cleaning temperature, but also the substrate off-angle. The surface after thermal cleaning became rough for the substrate with off-angle less than 0.05°. In the case of nonpolar and semipolar planes after thermal cleaning, surface morphologies and etching rates were strongly dependent on the planes. A flat surface was maintained at cleaning temperatures up to 1100 °C for the plane, but the surface of the plane became rough with increasing cleaning temperature.

We carried out the selective-area growth of GaN and fabricated InGaN/GaN MQWs on non- and semi-polar bulk GaN substrates by MOVPE. The differences in the GaN structures and the In incorporation of InGaN/GaN MQWs grown on non- and semi-polar GaN substrates were investigated. In the case of selective-area growth, different GaN structures were obtained on GaN, GaN, and GaN substrates. A repeating pattern of and facets appeared on GaN. Then, we fabricated InGaN/GaN MQWs on the facet structures on GaN. The emission properties characterized by cathodoluminescence were different for and facets. On the other hand, for InGaN/GaN MQWs on non- and semi-polar GaN substrates, steps along the a-axis were observed by AFM. In particular on GaN, undulations and undulation bunching appeared. Photoluminescence characterization indicated that In incorporation increased with the off-angle from the m-plane and also depended on the polarity.