Degree Of Relaxation Research Articles

Motion Recognition and an Accuracy Comparison of Left and Right Arms by EEG Signal Analysis

An electromyogram (EMG) is a signal for muscle output that indicates the degree of muscle contraction and relaxation. For these muscle signals to be output, certain signals must be received from the brain. To analyze these relations, electroencephalograms (EEGs) of the brain are measured to extract brain waves that are active at that time, although it is difficult to identify or distinguish expression patterns of the brain signal through EMG output. However, the brain signal operates via a partially reached signal and transmits the results of the operation. In this study, we analyze signals transmitted in this process and confirm whether human motion can be predicted from brain signals. It is not easy to guess the exact protocol of the brain using a general method, because a biosignal is a signal that differs from person to person. However, by analyzing the signals displayed by a particular user through actions, it is possible to determine the presence or absence of a signal to distinguish muscle movements. In the course of signal transduction, the energy of the left and right brain waves changes in the form of energy or signals that cause an arm’s movement. Responding to this, we analyze the signal transmission process of brain signals and EMGs to analyze loss and generated output. We extract EEG data from brain waves and determine EMG signals from the energy characteristics; we then collect and merge the results of spectra analysis through the Common Spatial Pattern (CSP) filter and explore the basis for predicting wills during muscle signals and stimulation transmission. The active information of the data within the working time of left and right brain waves depends on the changes of the left and right brain waves. It is proposed that the appearance of similar signals at these specific timescales can help identify the operations of the arms and outputs by the left and right biceps.

Study of dephasing mechanisms on the potential profile of a nanowire FET

The objective of this work is to study the dephasing mechanisms in a channel of a nanowire FET. A self-consistent Non-Equilibrium Green’s function method is applied to model the channel current dephasing. The potential profile of the channel is obtained by varying the degree of phase and momentum relaxation independently. Studies are performed by invoking both phase and momentum relaxation mechanisms in the FET channel current. The dephasing strength is varied from 0.0003 eV2 to 0.3 eV2. The potential profile across the channel shows a linear behavior under very high value of dephasing strength. Also, the shape of the output characteristics of the nanowire FET gets changed due to dephasing mechanisms.

Does the use of cardiopulmonary resuscitation feedback devices improve the quality of chest compressions performed by doctors? A prospective, randomized, cross-over simulation study

The aim of the study was to compare the quality of chest compressions (CCs) carried out with and without the use of the TrueCPR device during simulated cardiopulmonary resuscitations conducted by trainee doctors. The study was a prospective, randomized, cross-over simulation study. The study involved 65 trainee doctors who were tasked with performing a 2-min cycle of uninterrupted CCs under conditions of a simulated cardiopulmonary resuscitation of adults. CC were carried out in two scenarios: with and without TrueCPR chest compression support. Participants did not have experience in the use of CCs prior to this study. The depth of compressions in regard to CC techniques were varied by 45 mm (IQR 43-48) for manual CC and 53 mm (IQR 51-55) for the TrueCPR device (p < 0.001). The incidence of CCs with and without TrueCPR was: 112 (IQR 103-113) vs. 129 (IQR 122-135) compressions (p = 0.002). The degree of complete chest relaxation with the TrueCPR device was 95% (IQR 76-99) and without the device, 33% (IQR 29-38) (p < 0.001). In the simulation study performed, the use of the TrueCPR device resulted in a significant improvement in the quality of CCs in relation to frequency and depth of CCs and correctness of chest relaxation.

Relaxation of Residual Stresses in Bearing Rings Based on the Optimal Geometric Setup of Equipment for Centerless Running

This paper discusses the technological method of residual stress relaxation of bearing rings by centerless running with cylindrical rolls. Described a new approach to relieve residual stresses by centerless running of elastically-deforming rolls on the basis of the geometrical setup of the equipment. It was found that geometrical setup of the equipment influences an elastic strain of parts and the degree of residual stress relaxation. We obtained a mathematical model for calculation of setup parameters to ensure the required variation value of elastic strain of the part. The results of experiments confirm the influence of the geometric setup on the magnitude of residual stress relaxation.

Glass transition behavior of perpendicularly aligned thermotropic liquid crystalline phases consisting of long-chain trehalose lipids

The glass-forming ability of amphiphilic lipids has attracted attention owing to their specific potent applications. In this study, we used an aligned thermotropic liquid crystalline (LC) film made from a long-chain trehalose lipids (LTLs) and used the 2θ/ω scan analysis of the X-ray measurement to gain some insights into the glass transition behavior of glycolipids. A highly perpendicularly aligned single crystal-like film, in which the film thickness corresponds closely to the correlation length of the fluid lamellar (Lα) LC phase, was obtained after thermal annealing under reduced pressure. The temperature-dependence changes in the bilayer length of various LTL nanofilms, together with LTL powder samples, and film thickness of various LTL films were analyzed. As a result, the glass transition temperature (Tg) of LTL was successfully determined. Tg was the temperature at which the disappearance of the difference in the degree of structural relaxation occurred for the different cooling rates or the point of intersection of two extrapolated linear graphs with different thermal expanding properties. The longest bilayer length was observed at around Tg. Importantly, the layer number above Tg increased because of the development of thermal motion parallel to the film and subsequent rearrangement, whereas it was constant below Tg, persisting the layer structure due to the frozen state of sugar moiety. The experimental evidence suggested a unique feature of one glycolipid layer accompanying the glass transition for the Lα LC phase consisting of a long-chain glycolipid.

Fabrication of relaxed InGaN pseudo-substrates composed of micron-sized pattern arrays with high fill factors using porous GaN

Fully or partially relaxed micron-sized InGaN patterns with fill factors up to 69% were demonstrated via porosification of the underlying GaN:Si layer. The impact of the porosification etch conditions and the pattern geometry on the degree of InGaN relaxation were studied and monitored via high resolution x-ray diffraction reciprocal space maps. Additionally, a 45 nm redshift in the photoluminescence emission from InxGa1−xN/ InyGa1−yN multi-quantum wells (MQWs) regrown on bi-axially relaxed InGaN buffer layers was observed when compared to a co-loaded reference sample grown on GaN. The longer emission wavelength was associated with higher indium incorporation into the InGaN layers deposited on the InGaN base layers with a lattice constant larger than GaN, due to the reduced lattice mismatch between MQW and InGaN base layer, also called compositional pulling effect.

Finite element and experimental analysis of elevated-temperature fatigue behavior of IN718 alloy subjected to laser peening

Elevated-temperature fatigue life prediction method on laser peening (LP) treated IN718 alloy was proposed by using ABAQUS and MSC.Patran software. The elevated-temperature fatigue tests were subsequently performed to investigate the effects of LP on the fatigue life of specimens. Finally, the functional relationship model between fatigue life of the whole specimen and risk nodes was proposed to predict the ultimate elevated-temperature fatigue life according to experimental results and finite element analysis. The results indicated that the IN718 alloy served at 700 ℃ exhibited outstanding comprehensive mechanical properties due to strengthening phase precipitation. At elevated temperature, the relaxation degree of LP-induced residual stress and the change of mechanical properties dominated the ultimate fatigue life. The predicted fatigue life results obtained by the proposed calculated model showed an acceptable error compared with experimental results. Both simulation and experimental results indicated that LP treatment is beneficial to the improvement of the elevated-temperature fatigue properties of IN718 alloy.

Connection between gold dissolution in thiosulfate leaching and Cu(II) complexes during the cathodic process

The effect of the reduction half reaction of Cu(II) complexes on passivation and gold dissolution in the copper-ammonia-thiosulfate system were studied using electrochemistry and density functional theory (DFT). The results show that the cathodic process accounts for the surface passivation, aside from contributions made by thiosulfate decomposition during the anodic process. Copper sulfide and polysulfide are formed in the passivation layer during the reduction half reaction of Cu(II) complexes. The addition of common additives, such as ethylenediamine (EN) and ethylenediamine tetraacetic acid (EDTA), are able to not only remove the passive layer but also change the Cu(II) reduction half reaction. Tafel curves show that the gold leaching current in the EDTA-supplemented solution is higher than that in the EN-supplemented solution. Linear sweep voltammetry demonstrated that the reduction half reaction of Cu(II) complexes is controlled by the diffusion process, and the diffusion coefficient of the Cu(II) complex in the EN-supplemented solution and EDTA-supplemented solution is 0.64 × 10−6 cm2/s and 1.44 × 10−6 cm2/s, respectively. Density functional theory (DFT) studies showed that the lowest unoccupied molecular orbital (LUMO) of the mixed Cu(II)-ammonia-EDTA complex has lower energy than that of the mixed Cu(II)-ammonia-EN complex. Additionally, gold atoms on the surface that adsorbed the Cu(II)-ammonia-EDTA complex have higher relaxation degrees than those in the Cu(II)-ammonia-EN complex system. This explains why the gold concentration in the EDTA-supplemented solution is higher than that in the EN- supplemented solution. This study provides insight into the differences in gold dissolution during the cathodic process.

Strain relaxation of InGaN/GaN multi-quantum well light emitters via nanopatterning.

Strain in InGaN/GaN multiple-quantum well (MQW) light emitters was relaxed via nanopatterning using colloidal lithography and top-down plasma etching. Colloidal lithography was performed using Langmuir-Blodgett dip-coating of samples with silica particles (d = 170, 310, 690, 960 nm) and a Cl2/N2 inductively coupled plasma etch to produce nanorod structures. The InGaN/GaN MQW nanorods were characterized using X-ray diffraction (XRD) reciprocal space mapping to quantify the degree of relaxation. A peak relaxation of 32% was achieved for the smallest diameter features tested (120 nm after etching). Power-dependent photoluminescence at 13 K showed blue-shifted quantum well emission upon relaxation, which is attributed to reduction of the inherent piezoelectric field in the III-nitrides. Poisson-Schrödinger simulations of single well structures also predicted increasing spectral blueshift with strain relaxation, in agreement with experiments.

Vasorelaxant Effect of Prunus mume (Siebold) Siebold & Zucc. Branch through the Endothelium-Dependent Pathway.

Korean plum (Prunus mume (Siebold) Siebold & Zucc.) has long been used as a health food or herbal medicine in Asia. Previous studies have shown that several plants of the genus Prunus have vasodilatory and antihypertensive effects; we hypothesized that P. mume branches may have a vasorelaxant effect. In this study, we evaluated the effects and action mechanism of 70% ethanol extract of P. mume branch (PMB) on isolated rat aortic rings. Inhibitors such as NG-nitro-l-arginine methyl ester, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, methylene blue, indomethacin, atropine, tetraethylammonium chloride, glibenclamide, 4-aminopyridine and BaCl2 were used to investigate the mechanism of vasodilation responsible for the vascular relaxation. PMB (2–30 μg/mL) induced vasorelaxation in the presence of vascular endothelium, and all inhibitors used in this study affected the degree of relaxation. These results suggest that the vasorelaxant effect of PMB is endothelium-dependent and affects the nitric oxide-cyclic guanosine monophosphate pathway, prostacyclin pathway, muscarinic receptor pathway, and potassium channels. Our study explains that PMB may be another approach to hypertension treatment to reduce the burden of cardiovascular disease.

CMT disease severity correlates with mutation-induced open conformation of histidyl-tRNA synthetase, not aminoacylation loss, in patient cells

Aminoacyl-transfer RNA (tRNA) synthetases (aaRSs) are the largest protein family causatively linked to neurodegenerative Charcot-Marie-Tooth (CMT) disease. Dominant mutations cause the disease, and studies of CMT disease-causing mutant glycyl-tRNA synthetase (GlyRS) and tyrosyl-tRNA synthetase (TyrRS) showed their mutations create neomorphic structures consistent with a gain-of-function mechanism. In contrast, based on a haploid yeast model, loss of aminoacylation function was reported for CMT disease mutants in histidyl-tRNA synthetase (HisRS). However, neither that nor prior work of any CMT disease-causing aaRS investigated the aminoacylation status of tRNAs in the cellular milieu of actual patients. Using an assay that interrogated aminoacylation levels in patient cells, we investigated a HisRS-linked CMT disease family with the most severe disease phenotype. Strikingly, no difference in charged tRNA levels between normal and diseased family members was found. In confirmation, recombinant versions of 4 other HisRS CMT disease-causing mutants showed no correlation between activity loss in vitro and severity of phenotype in vivo. Indeed, a mutation having the most detrimental impact on activity was associated with a mild disease phenotype. In further work, using 3 independent biophysical analyses, structural opening (relaxation) of mutant HisRSs at the dimer interface best correlated with disease severity. In fact, the HisRS mutation in the severely afflicted patient family caused the largest degree of structural relaxation. These data suggest that HisRS-linked CMT disease arises from open conformation-induced mechanisms distinct from loss of aminoacylation.

Vascular Endothelial Cell Biology: An Update.

The vascular endothelium, a monolayer of endothelial cells (EC), constitutes the inner cellular lining of arteries, veins and capillaries and therefore is in direct contact with the components and cells of blood. The endothelium is not only a mere barrier between blood and tissues but also an endocrine organ. It actively controls the degree of vascular relaxation and constriction, and the extravasation of solutes, fluid, macromolecules and hormones, as well as that of platelets and blood cells. Through control of vascular tone, EC regulate the regional blood flow. They also direct inflammatory cells to foreign materials, areas in need of repair or defense against infections. In addition, EC are important in controlling blood fluidity, platelet adhesion and aggregation, leukocyte activation, adhesion, and transmigration. They also tightly keep the balance between coagulation and fibrinolysis and play a major role in the regulation of immune responses, inflammation and angiogenesis. To fulfill these different tasks, EC are heterogeneous and perform distinctly in the various organs and along the vascular tree. Important morphological, physiological and phenotypic differences between EC in the different parts of the arterial tree as well as between arteries and veins optimally support their specified functions in these vascular areas. This review updates the current knowledge about the morphology and function of endothelial cells, particularly their differences in different localizations around the body paying attention specifically to their different responses to physical, biochemical and environmental stimuli considering the different origins of the EC.

(Invited) Development of Germanium-Tin-Related Semiconductor Heterostructures for Energy Band Design in Electronic and Optoelectronic Applications

Group-IV element semiconductor materials, germanium tin (GeSn) and germanium silicon tin (SiGeSn) have attracted much attention for electronic and optoelectronic applications because of those unique properties; direct transition with a high Sn content, higher carrier mobility than Si and Ge, low growth temperature, and low thermal conductivity [1-3]. GeSiSn realizes the control of energy band structure independently on the lattice constant of alloy. Also, GeSiSn/Ge(Sn) heterostructure provides a type-I energy band alignment with sufficiently large energy band offsets at both conduction and valence band edges simultaneously with the lattice constant matching. That promises an effective carrier confinement structure for quantum well laser and high electron mobility transistor. On the other hand, the development of crystal growth technology for GeSn-related materials is still a challenge, since the thermal equilibrium solid solubilities of Sn in Ge and Si are very low compared to a required substitutional Sn content higher than 10%. It is necessary to understand the behavior of Sn atoms in the epitaxial growth and post deposition process and to control the stability of Sn at substitutional site in GeSn-related epitaxial layers. In addition, the development of interface engineering technology is required for not only GeSn/GeSiSn heterostructure but also metal/GeSn and insulator/GeSn structures for nano-scale electronic devices. Recently, we examined the formation of double heterostructure with GeSiSn/GeSn/GeSiSn layers on Ge substrate using a molecular beam epitaxy (MBE) system [4]. The hard x-ray photoelectron spectroscopy measurement reveals that the sufficiently large energy band offset can be formed at the valence band edge of its GeSiSn/GeSn interface. We also demonstrated that the carrier confinement with this GeSiSn/GeSn/GeSiSn double heterostructure effectively improved the efficiency of photoluminescence (PL) [5]. However, we also found that the crystalline quality of the heteroepitaxial layers significantly influence on the PL intensity and it is necessary to understand the key factor of the crystallinity of heterostructures in order to reduce the dislocation and point defect in the epitaxial layers. For the low temperature growth of GeSn and GeSiSn hetero-epitaxial layers on Ge using MBE, a biaxial compressive strain is often induced into the epitaxial layers, as a GeSn or GeSiSn layer is often grown pseudomorphically on Ge substrate. The compressive strain of GeSn is a disadvantage for enhancing the luminescence efficiency because a higher Sn content is generally required to the indirect-to-direct crossover for a compressively strained GeSn compared to the unstrained case. In order to improve the efficiency of luminescence, it is important not only to enhance the Sn content but also to control the strain structure. We developed the strain relaxation technology of GeSn epitaxial layer on a substrate or buffer layer. We found that the ion implantation into Ge substrate effectively enhance the strain relaxation of GeSn layer. The degree of strain relaxation achieved over 90% for the GeSn layer grown on the Ge substrate after the boron ion implantation with 3x1014 cm-2, while the compressively strained GeSn layer was pseudomorphically grown on the Ge substrate without the ion implantation. This work was partly supported with a Grant-in-Aid for Scientific Research (S) (No. 26220605) and the Core-to-Core Program ICRC-ACP4ULSI from the JSPS.

Determination of the Structural Relaxation Enthalpy Using a Mathematical Approach

Structural relaxation is a well-known phenomenon in amorphous materials such as amorphous solid dispersions. It is generally understood as a measure for molecular mobility and has been shown to impact certain material properties such as the dissolution rate. Several quantification methods to evaluate structural relaxation using differential scanning calorimetry have been proposed in the past, but all approaches exhibit disadvantages. In this work, a mathematical model was developed and fitted to calorimetric data enabling the analysis of the structural relaxation enthalpy by separating the structural relaxation peak from the underlying glass transition. The proposed method was validated using a parameter sensitivity analysis. Differently stressed amorphous samples were analyzed applying the new model and the results were compared to commonly applied quantification methods in literature. The proposed method showed high robustness and accuracy and overcame the observed disadvantages of the established methods. The heating rate dependence of the calculated structural relaxation enthalpy was in accordance with theoretical considerations of previous studies, supporting the validity of the results. Thus, the proposed model is suitable to accurately quantify the degree of structural relaxation and should be a valuable tool for further investigations regarding the impact of structural relaxation on material properties.

High thermal stability of piezoelectric properties in tetragonal Pb(In1/3Nb2/3)O3-PbTiO3 single crystal

The representatives of relaxor ferroelectric (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZNT) and (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMNT) have been extensively studied due to their excellent dielectric and piezoelectric properties near the morphotropic phase boundary (MPB). However, low rhombohedral to tetragonal phase transition temperature and Curie temperature directly affect the performance and stability of devices, particularly for high-power ultrasonic transducers. In this paper, the large size tetragonal 0.62Pb(In1/2Nb1/2)O3-0.38PbTiO3 (PINT) crystal was grown by the modified Bridgman technique. The crystals were oriented along the ⟨100⟩ direction to make bars with electrodes on (001) faces. The variation of the dielectric constant with temperature showed that the Curie temperature of PINT was 250 °C, and the maximum dielectric constant was 7.29 × 104 ɛ0. Fitting with Curie-Weiss’s law, we obtained that the relaxation degree was 1.44, which could mean that the dielectric properties of PINT are between relaxor ferroelectric and ordinary ferroelectric. At room temperature, electromechanical coupling coefficient k31 and piezoelectric strain constant d31 were 0.56 and 551 pC/N, respectively. Piezoelectric properties were relatively stable between room temperature and 175 °C. The material has good temperature stability in terms of piezoelectricity and dielectric properties. These results proved that the working temperature of the PINT crystal could reach about 175 °C, much higher than PZNT and PMNT single crystal, indicating their application in ultrasonic transducers at high temperatures.

High-quality GeSn Layer with Sn Composition up to 7% Grown by Low-temperature Magnetron Sputtering for Optoelectronic Application.

In this paper, a high-quality sputtered-GeSn layer on Ge (100) with a Sn composition up to 7% was demonstrated. The crystallinity of the GeSn layer was investigated via high-resolution X-ray diffraction (HR-XRD) and the strain relaxation degree of the GeSn layer was evaluated to be approximately 50%. A novel method was also proposed to evaluate the averaged threading dislocation densities (TDDs) in the GeSn layer, which was obtained from the rocking curve of GeSn layer along the (004) plane. The photoluminescence (PL) measurement result shows the significant optical emission (1870 nm) from the deposited high-quality GeSn layer. To verify whether our deposited GeSn can be used for optoelectronic devices, we fabricated the simple vertical p-i-n diode, and the room temperature current–voltage (I–V) characteristic was obtained. Our work paves the way for future sputtered-GeSn optimization, which is critical for optoelectronic applications.

The effects of a knot and its conformational relaxation on the ejection of a single polymer chain from confinement

The ejection of a single polymer chain out of confinement is a ubiquitous phenomenon in various engineering and biological processes. A virus, for example, ejects a DNA from its viral capsid to a host cell in order to infect the host. The ejection of a polymer chain is often relatively fast such that the polymer hardly relaxes its conformation and stays in nonequilibrium states during the ejection. However, the effects of the nonequilibrium conformation on the ejection process still remain unanswered, especially when a complicated conformation such as a knot exists. In this study, we employ a generic coarse-grained model and perform extensive molecular simulations to investigate how the knot and its conformational relaxation would affect the kinetics of the ejection process. We find that the ejection becomes slower by a factor of nine or more when the polymer chain forms a knot conformation inside the confinement. The knot conformation makes the polymer chain highly tensed, thus hindering the polymer from being pulled from the capsid. In order to investigate the effect of the knot and its conformational relaxation systematically, we tune the molecular parameters of the polymer chain and control the degree of relaxation of the knot conformation. The relaxation of the knot conformation facilitates the ejection process significantly.

Impact of the substrate lattice constant on the emission properties of InGaN/GaN short-period superlattices grown by plasma assisted MBE

Abstract In this work we investigate InGaN/GaN short period superlattices (SPSLs) grown on (0001) GaN and on relaxed In0.2Ga0.8N buffers with varying degree of plastic relaxation. The SPSLs were fabricated by plasma assisted molecular beam epitaxy (PAMBE). Despite the nominal SPSL structure consisted of InN monolayers (MLs) embedded in GaN barriers, we observed single monolayer InGaN layers instead of InN. We study the photoluminescence (PL) of such SPSLs as a function of the substrates lattice constant. Increase of the substrate lattice constant from a = 3.183 A (for GaN grown on sapphire) to a = 3.216 A resulted in a peak emission shift from 379 nm to 419 nm. We attribute the PL red-shift to the increased In incorporation in the ML-thick InGaN on relaxed buffers as a consequence of the reduced lattice mismatch between the substrate and the film. Our experiment confirms that coherent growth of InN is prohibited on GaN and points out the important role of substrate lattice constant engineering for realization of InN/GaN SPSLs.

Evaluation of the low-cycle fatigue strength of Sn3.0Ag0.5Cu solder at 313 and 353 K using a small specimen

Abstract This study performs fatigue tests by using a small specimen of Sn3.0Ag0.5Cu solder at 313 and 353 K. The specimen has a 3 mm-diameter gage section and a gage length and total length of 6 and 55 mm The specimen is heated in an electric furnace to control the temperature within ±1 K from the target temperature. The strain ranges employed are 0.5 %, 0.7 %, 1.0 %, and 1.5 %. A triangular waveform with 0.5 % × s−1 strain rate is adopted. The number of cycles to failure (failure life) Nf is defined as the number of cycles that causes a 25 % decrease of stress amplitude from that at the middle of the lifespan or at specimen breakage. The relationship between the strain range and failure life at 313 and 353 K coincides well, and no variation of the failure life with the test temperature is identified. Stress amplitudes decrease with increasing cycles and decrease faster for higher strain ranges because of higher crack propagation rates. The degree of relaxation in the stress amplitude is larger at 353 K than at 313 K. Crack observation of the fatigued specimens is performed to discuss the relationship between crack propagation and the failure life of solders. The relationship among slips, microcracks, and main cracks is discussed, and the mechanisms for fatigue failure are proposed. Almost no change in the crack morphology is observed at 313 and 353 K, and this result is related to the lack of changes in the failure mechanism because of the change in the test temperature.

Formation and optoelectronic property of strain-relaxed Ge1−x−ySixSny/Ge1−xSnx/Ge1−x−ySixSny double heterostructures on a boron-ion-implanted Ge(001) substrate

We have investigated the formation and optoelectronic properties of strain relaxed Ge1−x−ySixSny/Ge1−xSnx/Ge1−x−ySixSny double heterostructures on ion-implanted Ge substrates. The strain relaxation of Ge1−x−ySixSny and Ge1−xSnx epitaxial layers was achieved using an ion-implanted Ge substrate. The maximal degree of strain relaxation (DSR) of the Ge1−xSnx layers was evaluated to be 46%. In addition, we obtained a sharp and strong peak in the photoluminescence (PL) spectra from the sample with a DSR of 46%, while no strong peak was detected from a sample with a smaller DSR (22%). From the theoretical calculation of the energy band structure and the measurement temperature dependence of the PL intensity, the sharp and strong peak can be explained by the transition from an indirect to direct bandgap semiconductor due to the increase of the DSR and a concomitant increase of the Γ-valley electron population. Moreover, the PL intensity increases by the improvement of the crystallinity by a post deposition annealing process.