Si Ratio Research Articles

Formation of ultra-thin nickel silicide on SiO2 using Si/Ni/Si structures for oxidation control

We have demonstrated the formation of ultrathin Ni silicide on SiO2 by annealing Si/Ni/Si structures and have systematically evaluated the impacts of the Si layer thickness on oxidation, surface roughening and the silicidation reaction. X-ray photoelectron spectroscopy analyses revealed that suppression of Ni oxidation due to the top Si layer makes it possible to form an ultrathin Ni silicide layer with a thickness of around 2 nm. Then, it turned out that the composition ratio of Ni and Si depends on not only the annealing temperature but also the initial thickness ratio of the top and bottom Si layers. Furthermore, this work clarified that the ultra-thin top Si layer has a large impact on the surface morphology during Ni silicide formation with diffusion and preferential oxidation.

Hydrothermal Synthesis of Cancrinite from Coal Gangue for the Immobilization of Sr.

The primary objective of this study is to investigate and develop a rapid and effective method for the immobilization of Sr in the event of a nuclear leakage incident. Coal gangue, an underutilized form of solid waste from the coal industry, can be used as a raw material for curing Sr due to its high content of silica-alumina oxides. In the present study, Sr was successfully solidified in cancrinite synthesized using a hydrothermal method with coal gangue as raw material. A stable cancrinite phase was formed at a relative alkali concentration of more than 6 M. When the Sr/Al(Si) ratio was <1/6, cancrinite was the only stable phase that varied with the hydrothermal temperature and time. When the Sr/Al(Si) ratio increased to 1/2, the cancrinite phase completely disappeared, and a new strontium feldspar phase (SrAl2Si2O8) appeared. PCT leaching experiments showed that when Sr/Al(Si) < 1/6, the Sr leaching rate of Sr-cancrinite samples obtained by hydrothermal synthesis at 180 °C for 24 h was very low.

Nanotextile 100% Si Anodes for the Next Generation Energy‐Dense Li‐ion Batteries

AbstractCombined with other materials and device improvements, Si anodes can provide a step change in Lithium‐ion battery properties, enabling cell energy density to exceed 400 Wh kg−1. Freestanding, large‐area anodes of 100% Si produced by a slurry‐free method without carbon or binders are introduced. Their structure, a dense network of interconnected high aspect ratio Si nanowires (Si NWs), is analogous to a nanotextile and provides handling like paper. In conventional liquid electrolytes, the anode capacity is 2500 mAh g−1 at high mass loadings (e.g., 6.6 mAh cm−2), and cycling stability is 76% after 200 deep cycles, and 100% after 1800 cycles when cycled at 1000 mAh g−1. The nanowire network structure reduces junction resistance between particles and prevents any pulverization upon cycling. Combined impedance and composition‐selective electron microscopy demonstrate that capacity fading is exclusively through the progressive increase of SEI thickness and resistance. Full cell capacity with NMC811 translates into an energy density of 420 Wh kg−1 at the true cell level.

Zeolites Derived from Natural Kaolinite for CO2 Adsorption

This manuscript deals with the synthesis of different types of zeolites from natural kaolinite samples for CO2 adsorption. A zeolite A was prepared from kaolinite by means of an alkaline fusion process, followed by hydrothermal treatment, whereas a highly crystalline zeolite X was synthesized by optimizing the previously mentioned synthetic procedure. In detail, the SiO2/Al2O3 molar ratio in the preliminary mixture was modified with the addition of a secondary silicon source (sodium silicate) in order to obtain the one required for zeolites X. The physicochemical properties of the pristine clay and of the different zeolites were investigated by means of a multi-technique approach, including XRPD; SEM-EDX; 23Na, 27Al and 29Si MAS NMR spectroscopy; and N2 physisorption analysis at 77 K. Since the Si and Al molar ratios and reactivities are key parameters for the synthesis of zeolites, these aspects, primarily related to the use of a naturally occurring aluminosilicate as the raw material, have been investigated for their correlation with the physicochemical properties of the synthetic products. Moreover, by means of a custom-built volumetric apparatus, the CO2 adsorption capacity of the resulting zeolites at low gas pressures (&lt;1 bar) and at 25 °C was assessed.

Spectroscopic diagnostic of the footpoints of the cool loops

ABSTRACT Statistically, the cool loop’s footpoints are diagnosed using Si iv resonance lines observations provided by Interface Region Imaging Spectrograph (IRIS). The intensity and full width at half-maximum (FWHM) of the loop’s footpoints in β–γ active regions (ARs) are higher than the corresponding parameters of footpoints in β ARs. However, the Doppler velocity of footpoints in both ARs are almost similar to each other. The intensities of footpoints from β–γ AR is found to be around nine times that of β AR when both ARs are observed nearly at the same time. The same intensity difference reduces nearly to half (four times) when considering all ARs observed over 9 yr. Hence, the instrument degradation affects comparative intensity analysis. We find that Doppler velocity and FWHM are well correlated while peak intensity is neither correlated with Doppler velocity nor FWHM. The loop’s footpoints in β–γ ARs have around four times more complex Si iv spectral profiles than that of β ARs. The intensity ratios (Si iv 1393.78 Å/1402.77 Å) of the significant locations of footpoints differ, marginally, (i.e. either less than 1.9 or greater than 2.10) from the theoretical ratio of 2, i.e. 52 per cent (55 per cent) locations in β (β–γ) ARs significantly deviate from 2. Hence, we say that more than half of the footpoint locations are either affected by the opacity or resonance scattering. We conclude that the nature and attributes of the footpoints of the cool loops in β–γ ARs are significantly different from those in β ARs.

Comparative Analysis of FSE T2 Weighted, Chemical Shift and Dynamic Contrast-Enhanced MR Imaging in the Characterization of Adrenal Masses Based on Qualitative and Quantitative Parameters.

The purpose of our study was to investigate the role of different magnetic resonance imaging (MRI) parameters in the characterization of adrenal masses. A total of 150 patients who presented with 186 adrenal tumors were retrospectively evaluated in this study. Final patient cohort consisted of 17 pheochromocytomas, 3 adrenocortical carcinomas, 24 metastases, 31 lipid-poor adenomas and 111 lipid-rich adenomas. We carried out a visual assessment on FSE (Fast spin echo)T2 weighted images and also calculated T2 signal intensity ratio of all adrenal masses and also performed a qualitative assessment on chemical shift imaging (CSI) together with quantitative calculation using Adrenal to spleen signal intensity (si) ratio and Adrenal si index formulas. On dynamic contrast-enhanced sequences, visual assessment based on enhancement patterns on late-arterial phase images was performed and also mean signal intensity measurements were carried out. All examinations were interpreted by two abdominal radiologists in consensus who were blinded to the clinical and pathological findings. Statistical analysis was performed. On FSE T2 weighted imaging, isointense to liver and slightly hyperintense than liver was found higher in benign cases, however, in malignant cases moderately and strikingly hyperintense than liver was higher than in benign cases (p=0.001, p<0.01). There was a statistically significant difference between the T2 signal intensity ratio values of adrenal tumor groups (p=0.001, p<0.01). In lipid-rich and lipid-poor adenoma groups, T2 signal intensity ratio values was significantly lower than in pheochromocytoma and metastasis cases. In malignant group, T2 signal intensity ratio values were found statistically significantly higher than in the benign group (p=0.001, p<0.01). There was a statistically significant difference between CSI visual assessment of adrenal tumor groups (p=0.001, p<0.01). Although moderate and significant signal intensity loss was usually detected in lipid-rich adenoma group, never detected in other tumor groups. There was also a statistically significant difference between benign and malignant adrenal tumor groups (p=0.001, p<0.01). In the malignant group, Adrenal to spleen si ratio values were found significantly higher whereas, Adrenal si index values were significantly lower compared to benign tumors (p=0.001, p<0.01). Based on malignancy, there was a statistically significant difference between adrenal tumor groups (p=0.001, p<0.01). Although capillary blush and homogenous type enhancement were more common in benign cases than in malignant ones, peripheral-patchy and strikingly capillary blush type enhancement was more frequent in malignant tumors. Based on malignancy, mean arterial signal intensity values of malignant tumors were statistically higher than benign tumors (p=0.001; p<0.01). Dynamic contrast-enhanced MRI protocol including CSI aids in the characterization of indeterminate adrenal masses. Herein, the combined use of qualitative and quantitative parameters enables more tumors to be recognized that otherwise would be indeterminate.

Preparation and Catalytic Performance of the Copper-Manganese-Silicon Catalysts for Dehydrogenation Reaction of 2-butanol

Cu-Mn-Si catalysts with copper-manganese oxides as the main constituents and silica dioxide as the supports were prepared by co-precipitation method. The performance of the catalysts for the dehydrogenation reaction of the 2-butanol to methyl ethyl ketone was tested. The effects of Cu and Mn ratios on the catalytic performance were investigated. The catalysts were characterized by XRD, SEM, H2-TPR, TG, BET and XPS, to reveal the catalytic mechanism. The results showed that after adding the manganese, the copper-manganese complexes were formed in the catalysts, which effectively improved the activity of the catalysts. XRD results showed that a new phase of Cu-Mn complex was formed in the fresh catalysts, and reduced copper species appeared in the spent catalysts; TPR results showed that the reduction temperature of the catalysts could be reduced by adding appropriate amount of manganese; XPS results showed that the proportion of Cu++Cu0 can be increased in the fresh catalyst and that of Cu2+ in the spent catalyst can be decreased after the addition of manganese. When the mole ratio of Cu, Mn and Si in the catalysts was 0.8:0.2:1, the conversion of 2-butanol could reach 94.9%, and the selectivity of methyl ethyl ketone was 98%.

ATOMIUM: Molecular inventory of 17 oxygen-rich evolved stars observed with ALMA

Context. The dusty winds of cool evolved stars are a major contributor of the newly synthesised material enriching the Galaxy and future generations of stars. However, the details of the physics and chemistry behind dust formation and wind launching have yet to be pinpointed. Recent spatially resolved observations show the importance of gaining a more comprehensive view of the circumstellar chemistry, but a comparative study of the intricate interplay between chemistry and physics is still difficult because observational details such as frequencies and angular resolutions are rarely comparable. Aims. Aiming to overcome these deficiencies, ATOMIUM is an ALMA Large Programme to study the physics and chemistry of the circumstellar envelopes of a diverse set of oxygen-rich evolved stars under homogeneous observing conditions at three angular resolutions between ~0.02″−1.4″. Here we summarize the molecular inventory of these sources, and the correlations between stellar parameters and molecular content. Methods. Seventeen oxygen-rich or S-type asymptotic giant branch (AGB) and red supergiant (RSG) stars have been observed in several tunings with ALMA Band 6, targeting a range of molecules to probe the circumstellar envelope and especially the chemistry of dust formation close to the star. We systematically assigned the molecular carriers of the spectral lines and measured their spectroscopic parameters and the angular extent of the emission of each line from integrated intensity maps. Results. Across the ATOMIUM sample, we detect 291 transitions of 24 different molecules and their isotopologues. This includes several first detections in oxygen-rich AGB/RSG stars: PO v = 1, SO2 v1 = 1 and v2 = 2, and several high energy H2O transitions. We also find several first detections in S-type AGB stars: vibrationally excited HCN v2 = 2,3 and SiS v = 4,5,6, as well as first detections of the molecules SiC, AlCl, and AlF in W Aql. Overall, we find strong correlations between the following molecular pairs: CS and SiS, CS and AlF, NaCl and KCl, AlO and SO, SO2 and SO, and SO2 and H2O; meaning both molecules tend to have more detected emission lines in the same sources. The measured isotopic ratios of Si and S are found to be consistent with previous measurements, except for an anomalously high 29Si/30Si ratio of 4 ± 1 in the RSG VX Sgr. Conclusions. This paper presents the overall molecular inventory and an initial analysis of the large ATOMIUM dataset, laying the groundwork for future work deriving molecular abundances and abundance profiles using radiative transfer modeling which will provide more rigorous tests for chemical models.

Conformal growth of GaP on high aspect ratio Si structured surface via plasma-enhanced atomic layer deposition

This article is concerned with the study of conformal growth of thin gallium phosphide (GaP) layers by plasma-enhanced atomic layer deposition (PE-ALD) on a Si structured surface. GaP layers were deposited on (100) silicon wafers with a structured surface in the form of silicon microcolumns and black silicon. Deposition process were carried out at temperature of 380 °C using trimethylgallium and phosphine precursors. According to transmission electron microscopy (TEM), GaP layers deposited by this method conformally grown on the high aspect ratio structured silicon surface. The energy-dispersive X-ray spectroscopy (EDX) study show that the distribution of the main components of the GaP layer is uniform alongside surface of the silicon microcolumns and wires. High resolution TEM study confirms that GaP layers on the surface of silicon microcolumns and wires are epitaxial with the inclusion of twin lattice defects. Therefore, this deposition method can be used for the conformal deposition of thin crystalline layers of GaP on structured silicon surfaces with a high aspect ratio.

(Digital Presentation) Operando X-Ray CT Analysis of Silicon-Solid Electrolyte Mechanical Interface of All-Solid-State Battery

Silicon has a theoretical capacity about 10 times that of graphite is expected to be one of the next-generation anode materials to further increase the capacity of batteries. However, silicon has a large volume change during charging and discharging, which result in poor cyclability. Although morphological change of silicon has been shown in a lot of previous studies, most of them are ex-situ observations using electron microscopes such as SEM and are two-dimensional observations1). Previous studies have shown that silicon may fulfill its potential as an all-solid-state battery anode material with the garnet oxide-based solid electrolyte2). Further understanding of the expansion and shrinkage mechanism of silicon is needed to improve battery performance using silicon anode. Synchrotron X-ray computed tomography (X-ray CT) is a technique that can measure the internal structure of a battery in three dimensions with micrometer-order spatial resolution in a short time. In addition, operando X-ray CT measurement is possible under charging and discharging in an all-solid-state battery3). In this study, we analyzed that morphological changes of silicon during charging and discharging by operando X-ray CT measurements. We used LiNi1/3Co1/3Mn1/3O2 (NCM), Li6PS5Cl (LPSCl) and acetylene black (AB), which were mortar-mixed in a mass ratio of 1:1:0.1 as the cathode composite material, and Si, LPSCl and AB in a mass ratio of 1:2.78:0.42 as anode composite material. Si｜LPSCl｜NCM all-solid-state cells were assembled. X-ray CT measurements at SPring-8 BL20XU using 20 keV X-rays while performing constant current charge/discharge measurement at 2.3×10-3 A cm-2. The pixel resolution was 0.5 µm. A silicon particle was extracted from the X-ray CT images obtained from X-ray CT measurements to observe the morphological changes of silicon during the charging and discharging reaction. Cracks were observed in the silicon particle due to silicon shrinkage during the delithiation process. In addition, the silicon/solid electrolyte interface changed so that the silicon formed shell voids at the surface of silicon particles. This indicates that the plasticity of the LPSCl solid electrolyte cannot follow the form change of the interface. However, shell voids in the interface were formed for all directions, but some parts remained in contact area between the silicon particles and the solid electrolyte. The isolation of silicon particles from the solid electrolyte interface is suggested to be one of the factors causing the poor cycle performance because of the lithium ion reaction path is limited.1) T. Li, J. Y. Yang, S.G. Lu, H. Wang and H. Y. Ding, Rare Metals, 32, 299-304 (2013).2) W. Ping, C. Yang, Y. Bao, C. Wang, H. Xie, E. Hitz, J. Cheng, T. Li and L. Hu, Energy Storage Materials, 21, 246-252 (2019).3) Y. Sakka, H. Yamashige, A. Watanabe, A. Takeuchi, M. Uesugi, K. Uesugi and Y. Orikasa, J. Mater. Chem. A, 10, 16602–16609 (2022).

Liquid-Phase Synthesis of the Li–Si–P–S–Cl Solid Electrolyte for All-Solid-State Li-Ion Battery

Sulfide solid Li-ion conductors can be applied as electrolytes for high-performance all-solid-state batteries. For establishing mass production of such sulfides, liquid-phase synthesis is an attractive alternative to conventional solid-state method. Nevertheless, the new method has only been adapted to limited compositions (i.e., the Li–P–S system) with resulting in low ionic conductivity values of < 1.5 mS cm−1 at room temperature1. This study reports the liquid-phase synthesis of solid electrolytes in the Li–Si–P–S–Cl system (Li9.54Si1.74P1.44S11.7Cl0.3: LSiPSCl)2 with the high ionic conductivity of 6.6 mS cm-1 at 298 K3.In liquid-phase method, it is essential to find appropriate dissolution conditions without decomposition reactions of the raw materials, but such conditions have not been found for Si. We investigated the dissolution conditions of Si in anhydrous acetonitrile (ACN), which typically promotes severe decomposition reactions of dissolved raw materials. However, it was found that SiS2 is highly soluble in ACN when mixed with Li2S in specific molar ratio. This composition was confirmed by ICP-AES, wherein the molar ratio of Si : Li in the homogeneous solution was determined to be 1:1. Based on this finding, LSiPSCl was synthesized by the liquid-phase approach (Fig. 1a). Two homogeneous solutions containing either (Li, Si, and S) or (Li, P, and S)4 were prepared separately and then combined. Subsequently, LiCl and Li2S were added to obtain the precursor slurry solution. The precursor slurry solution was dried at 453 K under vacuum to remove all the solvent and sintered by heating at 748 K to obtain the liquid-phase synthesized sample (L-LSiPSCl).The L-LSiPSCl exhibited high ionic conductivity of 6.6 mS cm-1 at 298 K, which was comparable to the value for the reference sample (S-LSiPSCl) synthesized by the solid-state method. All-solid-state battery cells were prepared to examine the applicability of L-LSiPSCl as a solid electrolyte (Fig. 1b), with In–Li alloy anode and the composite cathode consisting of L-LSiPSCl (or S-LSiPSCl) and LiNbO3-coated LiCoO2. The charge–discharge cycle was conducted at the current density of 0.096 mA cm-2, which corresponds to 0.2 C rate. After 100 cycles, the discharge capacity for the cell with L-LSiPSCl was 88% of its theoretical value (i.e., 137 mA h g-1 for 1.9–3.6 V vs. Li+ /In–Li), and its capacity retention was > 97%. The charge–discharge performance was slightly better than that of the cell with S-LSiPSCl. The possible slight improvement might be attributed to the characteristic particle properties of L-LSiPSCl; scanning electron microscopy and micro-Raman spectroscopy indicated L-LSiPSCl is composed of aggregated particles with pores and carbides on particle surface. Overall, this study expanded the applicability of liquid-phase synthesis and implied its potential merits for sulfide Li-ion conductors for all-solid-state batteries.Reference1) A. Miura et al., Nat. Rev. Chem., 3, 189 (2019)2) Y. Kato et al., Nat. Energy, 1, 16030 (2016)3) T. Ito et al., J. Mater. Chem. A, 10, 14392 (2022)4) M. Calpa et al., Chem. Mater., 32, 9627 (2020) Figure 1

PENGARUH STRUKTUR MODAL, LIKUIDITAS, STRUKTUR KEPEMILIKAN DAN UKURAN PERUSAHAAN TERHADAP PROFITABILITAS PERUSAHAAN INDEKS LQ45 PERIODE 2017-2022

The purpose of this study is to analyze the influence of capital structure (DER), liquidity (si Ratio), ownership structure consisting of the Managerial Ownership (KM) and institutional ownership (KI) and company size (Size) on profitability (ROA). The population used is LQ45 Index companies listed on the Indonesia Stock Exchange for the 2017-2022 period. The method of determining the sample used in this research is pur-posive sampling according to predetermined criteria. The analysis technique used in this study is multiple linear regression analysis using SPSS-25. The test results show that the Debt to equity ratio and managerial ownership have no significant positive effect on profitability (ROA). Cash ratio and Size have a significant negative effect on profitabil-ity (ROA). Institutional ownership has a significant positive effect on profitability (ROA).

Crystal growth, scintillation properties and silicon-germanium ratio concentration optimization of BGSO: An excellent scintillator for dual-readout calorimeter

Bismuth silicate-germanate (Bi4Ge3xSi3(1-x)O12) crystals are successfully grown with the modified Bridgman technique. The X-ray diffraction, transmittance spectra, radioluminescence spectra and scintillation properties of these crystals are investigated at different ratios of Ge and Si. Furthermore, the XEL peaks of BGSO crystals exhibit a red-shift with the increase of Ge content. Meanwhile, the light yield and energy resolution of crystals represent obviously variation with changing of Ge and Si contents in the crystal. Density-functional theory (DFT) calculations were performed for energy band structure and geometry optimizations of Bi4Ge2.4Si0.6O12 crystal. The calculated energy band of BGSO crystal is 3.957 eV, which is different from that of BSO and BGO crystals. The results of DOS and PDOS calculated by CASTEP package reveal that Si/Ge–O and Bi–O interactions play a critical role in the band gap of BGSO crystal.

Effects of oxygen loading on the red-luminescence of non-bridging oxygen hole centers in γ-irradiated silica glasses

Ultra-high purity Corning 7980 and Corning 7979 silica glasses, respectively with high and low contents of hydroxyl and hydrogen, were specifically selected to investigate the effects of O2 loading on the 1.9 eV red luminescence of the gamma-ray induced non-bridging oxygen hole center (NBOHC), whose luminescence intensity is beneficial not only to predict the laser damage of silica but also to the targeted improvements in the preparation-treatment processes of silica. The UV trasmittance spectra, the UV excitation spectra, the visible emission spectra and the red emission lifetime decay curves were determined for these two types of the gamma-ray irradiated silica glasses before and after O2 loading. The content ratios of Si dangling bond (Si-E′) to NBOHC in silica glasses before and after O2 loading are estimated. The formation precursors and other related defects for NBOHC, such as Si-E′, Si-O-Si bond, Si-O-H bond, peroxy radical and linkage, oxygen-deficient centers ODC(I) and ODC(II), etc, are discussed. The bandwidths of the excitation and emission spectra before and after O2 loading are compared at the lower energy side of the spectra. The average emission lifetimes and especially the decay curves of the red luminescence before and after O2 loading are analyzed. There appear two types of NBOHCs with and without neighbouring hydrogen interaction at room temperature, respectively corresponding to the shorter and longer lifetime components. After O2 loading, the shorter lifetime component disappears and becomes the longer one, indicating that the hydrogen-bonded NBOHC is altered into the non-bonded. It is suggested that the analysis of the shorter and longer lifetime components of the red luminescence can be utilized in the laser damage prediction as well as the preparation and treatment processes of silica.

Experimental study on the performance of a high compression ratio SI engine using alcohol/ammonia fuel

Ammonia, ethanol, and methanol are promising carbon-neutral fuels in the future. Therefore, the use of alcohol fuels to enhance ammonia combustion in engines deserves further study. The performance of a spark ignition engine with high compression ratio at various loads was experimentally investigated to determine the impact of fuel composition. Specifically, ethanol and methanol were chosen as the primary fuels, while gasoline was assigned as the control group. Gaseous ammonia was introduced through the intake port. The results show that ammonia increases indicated thermal efficiency (ITE) in different ways when blended with different fuels, with the gasoline group obtaining higher ITE (2.8 % relative increase) by optimizing combustion phase, and the ethanol and methanol groups directly enhancing ITE (1.2 % and 0.8 % relative increase) with the same combustion phase due to reduced heat transfer loss. Methanol group shows a more ideal combustion duration under low loads and large ammonia blending ratios and achieves higher ITE due to higher oxygen content. Replacing gasoline with ethanol and methanol significantly reduces greenhouse gas (GHG) under similar NOx emissions, and the advantage of blending carbon-containing fuels with ammonia to reduce GHG is more significant under high loads and large ammonia blending ratios.

Differentiation of bone metastases from benign red marrow depositions: utilizing qualitative and quantitative analysis of conventional T1-weighted imaging and fat-suppressed T2-weighted imaging.

To distinguish bone metastases (BMs) from benign red marrow depositions (BRMs) by qualitative and quantitative analyses of T1-weighted imaging and fat-suppressed T2-weighted imaging (T2 FS). For 75 lesions including 38 BMs and 37 BRMs, tworadiologists independently evaluated magnetic resonance images by qualitative (signal intensity [SI] of lesions compared to that of normal muscle [NM] or normal bone marrow [NBM]) and quantitative (parameters of the region of interests in the lesions, including T1 ratio [T1 SI ratio of lesion and NM], T2FMu ratio [T2 FS SI ratio of lesion and NM], and T2FMa ratio [T2 FS SI ratio of lesion and NBM]) analyses. Hyperintensity relative to NM or NBM on T2 FS was more frequent in BMs than in BRMs (100% vs 59.5%-78.4%, respectively; P ≤ 0.001) but also was present in more than half of BRMs. All quantitative parameters showed a significant difference between BMs and BRMs (T1 ratio, 1.075 vs 1.227 [P = 0.002]; T2FMu ratio, 2.094 vs 1.282 [P < 0.001]; T2FMa ratio, 3.232 vs 1.810 [P < 0.001]). The receiver operating characteristics areas under the curves of T2FMu and T2FMa ratios were clinically useful (0.781 and 0.841, respectively) and did not demonstrate statistically significant differences. The quantitative analysis of T2 FS facilitates distinguishing between BMs and BRMs, regardless of whether the reference was NM or NBM. Quantitative parameters derived from T2 FS facilitate differentiation of BMs BRMs without additional scans. The role of NBM as an internal standard for T2 FS to differentiate between BMs and BRMs is similar to that of NM.

Combustion stability, RGF and pressure referencing effect on HRR for a high compression ratio SI engine with natural gas lean mixtures

The knocking and heat release based on cylinder pressure trace is a widespread practice in combustion diagnostic for conventional SI engines. The accuracy depends on quality of measured in-cylinder pressure, thermodynamic models and parameters feeding such models. In non-conventional engine, common models to assess engine operation, do not satisfy properly expected standard, thus application of new methods and models is required. This study presents the determination of knocking intensity by in-cylinder pressure and cycle-to-cycle variability for operation analysis, the effect of referencing pressure and residual gas fraction on heat release for non-conventional SI engines with high compression ratio with natural gas at partial loads and lean mixture. Higher spark timings was achieved at 21 degrees, limited by low occurrence audible knock for KI20 over 0.04 bar. Compression ratio 15.5, engine speed at 1800 rpm, air-cooled system, and equivalence ratio of 0.73 make limited the operation. KI20 of 0.072 was reached at IMEP 3.96 bar and spark timing of 21 degrees. Maximum CoV of KI20 was 27.1. Pressure referencing shows low differences in polytropic coefficients of 1.34. Slight difference for RGF generates differences in the mass burned up to 12%, and around 0.4 degrees in combustion duration.

Concentration dependent cyan emission by europium‐doped borosilicate glasses

AbstractAt present, doping of different alkaline‐earth metal ions is mainly used to tune the emission peak of europium (Eu) ions in glasses. However, the optimization of Eu‐doped glasses is hindered due to limited discussion on the relationship between local glass network structure, concentration of Eu ion dopants, and visible light emission by Eu ions. In this study, we prepared two series of borosilicate glasses doped with Eu ions, by varying the ratio of SiO2 to B2O3 and adjusting the concentration of Eu ion dopants to obtain cyan emission. The optical properties, structure, and differential scanning calorimetry (DSC) of the investigated glasses were systematically studied. With gradual increase in the content of SiO2, red shifting from 471 nm to 492 nm was observed under excitation at 410 nm, with the introduction of Eu2O3 also causing a redshift from 471 nm to 488 nm. The spectral results also revealed that under excitation at 410 nm all the glass samples exhibited cyan emission, with the optimal cyan peak at 492 nm (Si‐45) and the strongest cyan emission at Eu‐0.4 (480 nm). By adjusting the concentration ratios of Si to B in europium‐doped borosilicate glass, it was observed that by altering the [SiO4] tetrahedra, [BO4] tetrahedra, and [BO3] triangles within the glass ultimately cyan emission can be achieved. By varying the doping concentration of Eu ion to change the degree of local Eu ion clustering in the glass system, cyan emission can be achieved by tuning the emission peak.

Experimental investigation of the influence of pre-chamber structural parameters on combustion and emission characteristics of a high compression ratio SI engine

The passive pre-chamber exhibits great potential for practical applications in the internal combustion engine due to its simple structure. However, it faces difficulties in scavenging process, making optimization of pre-chamber structure particularly important. In this study, the effects of pre-chamber ignition systems with different structures and original spark ignition were conducted on a high compression ratio direct-injection SI engine to investigate the combustion, performance, and emission characteristics. The results show that the increase in pre-chamber volume weakens the in-cylinder combustion process and engine performance, while increasing the pre-chamber orifice diameter can enhance the combustion stability at medium to high loads, but will weaken the engine performance at low load. Compared to spark ignition, pre-chamber ignition results in an earlier 50% combustion position, a shorter combustion duration and lower COVIMEP, with these effects becoming stronger as load increases. At high load, the pre-chamber ignition (PC1) advances the 50% combustion position by 5.6°CA and shortens the combustion duration by 16.7%. In addition, the indicated thermal efficiency of the pre-chamber ignition achieves an increase of 0.84% at the optimal point and 2.5% at high load. Overall, using the smaller orifice diameter and volume in the pre-chamber can improve in-cylinder combustion process and increase thermal efficiency across the load range. For emission analysis, the pre-chamber ignition leads to an increase in NOx and HC emissions due to the influence of in-cylinder combustion temperature and quenching effect, while the CO emissions are similar to spark ignition.

Correlation between pitting susceptibility and surface acidity, point of zero charge of passive film on aluminum: Influence of alloying elements

The pitting potential, intrinsic surface acidity, point of zero charge of passive film on Al are studied using first-principles calculations to establish their relationships. Influences of alloying elements Zn, Cr, Nb, Si, Mo and Sc on adsorption of NH3 and NaCl, pHpzc of Al2O3 and pitting susceptibility of Al are investigated. The efficiency for enhancing pitting resistance of Al is evaluated, yielding the ratios Si: Zn: Cr: Mo: Nb: Sc = 1.8: − 0.3: 1: 1.9: 1.4: 0.2. A model for the dependence of pitting potential on the concentration of alloying elements in Al alloy matrix is developed, based on effects of alloying elements on the surface charge of passive film. The effects of Sc on pitting potential and pHpzc of Al oxide are predicted based on the calculated results, which are supported by electrochemical measurement, XPS analysis and contact angle titration.