Types Of Structures Research Articles

Practical approach for sand-shale mixtures classification based on rocks multi-physical properties

Sandstones are the most common reservoir rocks, providing reservoirs for oil and gas and serving as reservoirs for groundwater. The Gulf of Mexico is known for its sand-shale mixtures and potential for its oil and hydrate gas resources in sandstone units. Understanding these variations is essential for assessing hydrocarbon potential and unconventional prospectivity. In this study, we utilized the Elastic, Electrical, and Radioactive (EER) properties of rocks for lithological categorization of well logging data, leading to the development of a novel rock physics template. The electrical and radioactive properties of the rocks facilitated a broad lithological classification, while their elastic characteristics helped distinguish between porous and low-porosity zones. Electrical and radioactive properties are utilized for well data classification because in sandstone formations, there is a decrease in log gamma and an increase in log resistivity. As a result, these opposing shifts in the two geophysical logs enhance the spread of data points on the lithological resistivity-gamma ray scatter plot, thereby simplifying the process of lithological categorization. Ultimately, the well logging data was sorted into three distinct categories: low shale sands (shale volume < 30 %), sand-shale mixtures (shale volume = 30 to 80 %), and shale-dominated areas. Subsequently, the Thomas Stieber model was employed to identify the types of clay minerals present in both sandstones and sand-shale mixtures. The model's findings revealed that dispersed type clay minerals are predominantly found in sandstones, with laminar and structured types being relatively rare. However, in sand-shale mixtures, both dispersed and laminar clays observed.

Ultra-broadband achromaticity of metalens with low-relative phase enabled by wide-band fusion

Metalenses have a high design degree of freedom in controlling the light field and excellent performance in chromatic aberration elimination. However, in designing ultra-broadband achromatic metalenses, integrating multiple types of unit structures is necessary to compensate for phase differences caused by different incident wavelengths. Here, we propose an ultra-broadband achromatic metalens composed only of a single type of square nano-pillar. which controls the entire operating band by utilizing three wide-band fusions, and have characteristics depending on the phase coverage and relative phase. In the operational range of 2–5 μm, the achromatic metalens demonstrates a maximum focal shift of 2.1 μm. The average focal shift is 0.98 %, the average NA value is 0.35, with an average relative phase of 0.77π. The average transmittance and focus efficiency are 94.17 % and 58.7 %, respectively. This broad-spectrum fusion design strategy simplifies manufacturing complexity while maintaining high focusing efficiency and transmittance levels throughout the entire operational bandwidth. This design approach can improve image resolution and quality by minimizing chromatic aberration.

The Effect of Ownership Structure on the Going Concern Companies Listed in the Iraqi Stock Exchange

The ability of the economic unit to continue is one of the basic assumptions for preparing financial statements. Therefore, users of these statements need to have a clear image of the unit’s performance and financial situation and to ensure that there is no indicator warning of financial distress. For example, there is a conflict of interest between the unit’s shareholders on the one hand and the management on the other hand. Therefore, this research seeks to study the effect of the difference in the nature of the ownership structure on the going concern of economic units. The research is based on the hypothesis that each type of ownership structure has a negative impact on the going concern unit. The research selected five economic units listed on the Iraqi Stock Exchange from the service sector as a sample for the research. Data is collected for the period extending from 2011-2021. The research used the survey method to measure the ownership structure and applied a Kida Model to measure going concern. The most significant results of the research are a negative effect of institutional ownership, concentrated ownership, and management ownership on the going concern of the unit, In contrast, the effect is positive for both government ownership and family ownership, and foreign ownership has no effect. Paper type: Research paper

Characteristics of the Spatial Structure of Traditional Villages in the Xinjiang Uygur Autonomous Region in China and Their Influence Mechanisms

Traditional villages are one of the basic types of rural revitalisation and one of the important carriers of cultural inheritance. This research is based on the data of 53 traditional villages in the Xinjiang Uyghur Autonomous Region with the aid of the ArcGIS10.8.1 spatial analysis platform. The study identifies the spatial evolution characteristics from the spatial distribution type, distribution direction, distribution density, distribution balance, etc., and explores their influence mechanisms. The study shows that 1. the spatial structure of traditional villages in Xinjiang was analysed as a cohesive structure type by using the nearest neighbour index method, which shows the evolutionary characteristics of the agglomerative tendency to increase gradually. Among them, Changji Hui Autonomous Prefecture and Turpan City have the highest degree of concentration. 2. The establishment and development of traditional villages in Xinjiang is mainly influenced by natural factors such as geographical features and hydrography. Social factors such as population distribution, transport conditions and economic progression have very important implications for the preservation and continuation of traditional villages.

Experimental evaluation on dynamic performance of medium–low-speed maglev vehicle running on low-positioned subgrade

ABSTRACT As a novel urban rail transit system with relatively low construction costs, medium–low-speed maglev transportation is currently experiencing rapid development in China. However, there have been rare studies on the experiments of medium–low-speed maglev vehicle passing curves and low-positioned subgrade. Therefore, this paper systematically conducts on-site dynamic tests on the Qingyuan Maglev Tourism Line. The experiment provides a detailed analysis of the dynamic characteristics of the vehicle system and subgrade under varying speeds up to 132 km/h. The study explores the impacts of operating speed, track layout, and type of girder structure. The results indicate that a significant increase in operating speed and the application of emergency braking intensify the dynamic response of the vehicle system. When passing through the R700m curve and low-positioned subgrade sections at different speeds, the primary vibration frequency of the sprung structure is below 2.5 hz, while the unsprung structure shows a wide frequency distribution. The peak frequencies of the vibration for the low-positioned subgrade are mainly distributed in the 60–140 hz range, and the vibration response of the girder remains at a low level. The Sperling index values, levitation gap, and lateral offset of the levitation electromagnet of the testing vehicle do not exceed 2.5, 4 mm, and 10 mm, respectively, indicating excellent ride comfort and stable levitation performance. The results of this test study provide a reliable assessment of the safety of the vehicle and subgrade system and would help precise modelling of vehicle and subgrade system in the future.

Investigation of Mechanical Properties and Microstructural Evolution in Pure Copper with Dual Heterostructures Produced by Surface Mechanical Attrition Treatment

Heterostructured materials consist of heterogeneous zones with dramatic variations in mechanical properties, and have attracted extensive attention due to their superior performance. Various heterostructured materials have been widely investigated in recent years. In the present study, a combination of two different types of heterogeneous structures, a surface bimodal structure and gradient structure, was designed using the traditional surface mechanical attrition treatment (SMAT) method in pure copper, and the mechanical properties and microstructural evolution of dual-heterostructure Cu were studied in depth. In total, 100 stainless steel balls with a diameter of 6 mm were utilized to impact the specimen surface at room temperature for a short period of time. In this work, the sample surface was divided into hard areas and soft areas, along with a roughly 90 μm gradient structure in the cross-sectional direction after 30 s of SMAT processing. After the partial SMAT processing, lasting 30 s, the strength increased to 158.0 MPa and a considerable ductility of 25.7% was sustained, which overcomes the strength–ductility trade-off. The loading–unloading–reloading (LUR) test was utilized to measure the HDI stress, and the result showed that the HDI stress of the partial SMAT sample was much higher than the annealed one, especially for the Cu-SMAT-30S specimen, the strength of which increased from 80.4 MPa to 153.8 MPa during the tensile test. An in situ digital image correlation (DIC) investigation demonstrated that the strain developed stably in the Cu-SMAT-10S specimen. Furthermore, electron backscatter diffraction (EBSD) was carried out to study the microstructural evolution after partial SMAT processing; the KAM value increased to 0.34 for the Cu-SMAT-10S specimen. This research provides insights for the effective combination of superior strength and good ductility in dual-heterostructure materials.

Serous Ovarian Carcinoma: Detailed Analysis of Clinico-Pathological Characteristics as Prognostic Factors

Background/Objectives: Serous ovarian carcinoma (SOC) is the most common subtype of epithelial ovarian cancer, with high-grade (HGSOC) and low-grade (LGSOC) subtypes presenting distinct clinical behaviours. This study aimed to evaluate histopathologic features in SOC, correlating these with prognostic outcomes, and explore the potential clinical implications. Methods: We analysed 51 SOC cases for lymphovascular space invasion (LVSI), tumour border configuration (TBC), microvessel density (MVD), tumour budding (TB), the tumour–stroma ratio (TSR), the stromal type, tumour-infiltrating lymphocytes (TILs), and tertiary lymphoid structures (TLSs). A validation cohort of 54 SOC cases from The Cancer Genome Atlas (TCGA) was used for comparison. Results: In the discovery set, significant predictors of aggressive behaviour included LVSI, high MVD, high TB, and low TILs. These findings were validated in the validation set where the absence of TLSs, lower peritumoural TILs, immature stromal type, and low TSR were associated with worse survival outcomes. The stromal type was identified as an independent prognostic predictor in SOC across both datasets. Inter-observer variability analysis demonstrated substantial to almost perfect agreement for these features, ensuring the reproducibility of the findings. Conclusions: The histopathological evaluation of immune and stromal features, such as TILs, TLSs, TB, TSR, and stromal type, provides critical prognostic information for SOC. Incorporating these markers into routine pathological assessments could enhance risk stratification and guide treatment, offering practical utility, particularly in low-resource settings when molecular testing is not feasible.

Epitaxial Growth of Multicolor Lanthanide MOFs by Ultrasound for Photonic Barcodes.

Epitaxially grown lanthanide metal-organic frameworks (Ln MOFs) exhibit multicolor and characteristic Ln emission with sharp emission bands, which are of great value in the field of information security and anti-counterfeiting. Epitaxial growth of Ln MOFs is generally achieved by solvothermal or hydrothermal methods, which suffer from challenges such as high reaction temperature and long growth time. Here, we report the fast epitaxial growth of multicolor lanthanide MOFs by an ultrasonic method at room temperature. The TbSmSQ shows a core-shell type structure with the Tb ion in the core and Sm in the shell within one crystal and exhibits the characteristic emission lines of Tb and Sm, respectively. The nonporous structure and large distance between lanthanide ions effectively avoid the influence of solvent vapor on the intensity and color of luminescence emission. Its application as photonic barcodes has been studied. This work demonstrates the feasibility of epitaxial growth of multicolor Ln MOFs by the ultrasonic method and its value for anti-counterfeiting and information security applications.

Crystal structure, Chemical Bonding, and Magnetism of α-Fe6Ga5: How Local Interactions Shape the Structure and Properties of Intermetallic Compounds.

α-Fe6Ga5 was synthesized from the elements as a polycrystalline powder. Its crystal structure was redetermined by high-resolution powder X-ray diffraction, which showed a complex monoclinic structure of the Fe6Ge5 type. The determined lattice parameters (a = 10.08380(6) Å, b = 7.97071(5) Å, c = 7.70489(5) Å, and β = 108.3062(2)°) differ notably from the previous reports. Despite possessing the same structure type as Fe6Ge5, α-Fe6Ga5 displays several distinctive features, such as short Ga-Ga bonds and distorted Fe layers. According to magnetization measurements, α-Fe6Ga5 is a soft ferromagnet with a high Curie temperature of 760 K, which is in stark contrast to the antiferromagnetic behavior of Fe6Ge5 reported in the literature. The electronic structure of α-Fe6Ga5 was studied theoretically using density functional theory-calculations, which showed the pronouncedly covalent character of the short Fe-Ga and Ga-Ga bonds. Similar calculations were performed for Fe6Ge5, which revealed stronger Fe-Ge interactions, which preclude the formation of short Ge-Ge bonds. In both cases, the theoretical calculations showed ferromagnetic instability, which leads to ferromagnetic ordering only in the case of α-Fe6Ga5, likely due to the different nature of Fe-Ga-Fe and Fe-Ge-Fe superexchange interactions.

Characteristics of flow structure of lateral inlet/outlet in pumped storage power stations

Investigating the complex separated flows in lateral inlet/outlets of pumped-storage power stations(PSPS) is crucial for optimizing their design to ensure safe and efficient operation. In this study, Large Eddy Simulations (LES) are employed to reveal the relationship between turbulence intensity and the distribution of coherent structures in separated flows, as well as the evolution characteristics of hairpin vortices. The flow separation is notably influenced by the vertical diffusion angles α, which causes recirculation zones at the top of the inlet/outlet, leading to significant local flow velocities at the trash racks and increasing the risk of flow-induced vibration damage. Areas of high turbulence intensity exist at the top and bottom of the core flow, caused by the propagation of corresponding streams of vortical flow, which is identified as the primary cause of head loss in the inlet/outlet. Based on the average turbulence intensity, the inlet/outlet can be divided into zones of sharp turbulence increase, high turbulence intensity, and decreasing turbulence intensity. The vortical flow mainly includes three types of coherent structures: attached vortices, hairpin vortices, and quasi-streamwise vortices. Among these, the frequency of top hairpin vortices and the growth angle of hairpin vortex packets are highly susceptible to α. The growth direction of hairpin vortex packets closely aligns with the direction of turbulence intensity propagation. These findings contribute to optimizing the design of inlet/outlet of PSPS.

Tree structures may be the leadership structures employed by group motions exhibiting hierarchy

Collective behaviors leading to various fascinating movement patterns are believed to be the product of complex interplay among individuals. Previous studies have identified two types of leadership structures in pigeon flocks, i.e., hierarchical networks and reciprocal relationships. However, both of these leadership structures are predicated based on data analysis and lack substantial empirical evidence. Additionally, it is difficult to delineate a direct correspondence between leadership structures and trajectory data for pigeon flocks because birds cannot report their leadership structure. Herein, based on experiments involving volunteers, we found that tree structures may serve as the leadership structures employed by group motions exhibiting hierarchy. In the tree structure, each follower follows its only leader during collective motions, and the single top leader determines the direction of collective motions. By employing the tree structure, we introduced a model for describing collective motions. A method for obtaining the leadership structure through experimental trajectory data was proposed. This strategy was used to analyze flight trajectory data from a pigeon flock and elucidate the pigeons' leadership relationships. Our model can simulate the collective behavior of pigeon flocks, thus accurately replicating the findings of previous experimental studies. The results of this study provide insights regarding the leadership structure in pigeon flocks and have implications for artificial collective systems, e.g., autonomous formation control of multiple unmanned aerial vehicles or unmanned surface vehicles. Published by the American Physical Society 2024

Impact of Flame Conditions on the Pd‐O Structure and Methane Oxidation Activity over Ceria Support

AbstractIn this work, we employed flame spray pyrolysis (FSP), a high‐temperature synthesis method, to control the formation of Pd structures on the CeO2 support. Multiple types of Pd structures deposited on CeO2 are observed on FSP‐made samples. Our results show that the oxidizing environment during FSP synthesis facilitates the formation of incorporated Pd2+ structures, along with highly dispersed Pd2+, Pd0 nanoparticles, and Pd° clusters formed under the reducing synthesis condition. Notably, these Pd2+ species remained stable at temperatures up to 400 °C. The catalysts containing both highly dispersed Pd2+ nanoparticles and incorporated Pd2+ species demonstrated superior methane oxidation activity, with higher turnover frequencies than those containing only one type of Pd2+ structure. However, hydrothermal pretreatment in the presence of water vapor led to partial deactivation, likely due to structural alterations in the Pd species or the interaction with the CeO2 support, which reduced the stability and effectiveness of the active sites. This study underscores the importance of both highly dispersed and incorporated Pd2+ species in enhancing catalytic performance and highlights the challenges posed by water‐induced deactivation in practical applications.

Impact of Climate and Vegetation Dynamics on the Ecosystem Services of Subtropical Forests—A Case Study of Baishanzu National Park Area, China

Forest ecosystems, as the primary component of terrestrial ecosystems, provide essential ecosystem services (ESs) critical for sustainable human development. However, changes in climate and vegetation can alter these forest ESs. Understanding the complex relationships between regional climate, vegetation, and ESs is key to ensuring the sustainable management of forest ESs. Therefore, this study, using Baishanzu National Park as a case example, analyzed the impacts of regional climate and vegetation dynamics (vegetation coverage, forest type, and forest structure) on forest ESs, specifically water yield (WY), soil conservation (SC), net primary productivity (NPP), and habitat quality (HQ). The results indicate that from 2000 to 2020, the forest Composite Index of Ecosystem Services (CIES) in Baishanzu National Park increased. Climate and vegetation dynamics have significant effects on forest ESs. Specifically, changes in WY and SC are primarily influenced by climate change, while changes in NPP and HQ are mainly affected by changes in forest type and structure. Complex trade-offs and synergies exist among different ESs, and the driving mechanisms of climate and vegetation changes on ES variations are also complex, involving both direct and indirect effects, with significant spatial heterogeneity. This study provides important references for the sustainable management and appropriate restoration of regional forest ESs.

Differences in Mathematical and Verbal Achievement Between Girls and Boys: The Heuristic Potential of the Structural Typing Approach in Large‐Scale Studies

ABSTRACTThe results of total testing from the years 2015–2022 on the mathematical and verbal achievement of Lithuanian pupils (N ≈ 250,000) are presented. These are the standardised tests from grades 4 to 12. The K‐Means method has discovered six types of achievement. The highest achievement type is dominated by girls (61.1%) who perform well on both mathematical and verbal tasks. The lowest achievement type is dominated by boys (57.4%) who solve both mathematical and verbal tasks extremely poorly. Each of these types makes up 1/5 of the population, and the gap between the means of their groups is about 2.5 standard deviations. The remaining four types of achievement are in the 20th to 80th percentile and make up about 60% of the population. Differences in means within the same type between mathematic and verbal achievement average 0.85 standard deviations or span one quartile. Gender differences are clearly visible in this subgroup: boys solve mathematical tasks better and verbal tasks worse; girls solve verbal tasks better and mathematical tasks worse. Big data may form a mixed distribution. It is appropriate to first discover the basic types of achievement and only then look for gender‐specific differences. Such a type‐building approach is heuristically superior to the conventional approach of working only with the mixed dataset.

Solid and hollow plasmonic nanoresonators for carrier envelope phase read-out

The geometry of gold plasmonic nanoantennae was numerically optimized to maximize their sensitivity to the carrier envelope phase (CEP) of the exciting ultra-short laser pulses. Three structure types, triangular, teardrop-shaped and plasmonic lens, were optimized in solid and hollow compositions as well. Hollow / solid singlets results in the largest/intermediate CEP dependent (Q1) – to – CEP independent (Q0) integrated current components’ ratio, while their Q1 was the smallest / intermediate. The largest / intermediate Q12/Q0 CEP sensitivity was achieved via solid / hollow plasmonic lenses due to their large near-field enhancement and Q1, while the Q1/Q0 ratio was smaller than for counterpart singlets.

Effects of moderate-intensity aerobic training on cardiac structure and function in type 2 mellitus diabetic rats: Based on echocardiography and speckle tracking

PurposeThe present study aimed to evaluate the cardiac function changes using Layer-specific Speckle-tracking echocardiography (LS-STE) induced by Moderate-intensity aerobic training (MIAT) in Type 2 diabetes mellitus (T2DM) rats. MethodsTwenty-six rats were divided into four groups: the Control group (Con), the Training control group (CT), the T2DM group (DM), and the T2DM training group (DT). The CT and DT groups underwent an 8 weeks MIAT. Cardiac structure and function were evaluated by echocardiography and LS-STE. ResultsCompared with the Con group, left atrial diameter (LAD), left ventricular end-diastolic diameter(LVEDD), relation wall thickness (RWT), and left ventricular mass (LVM) were significantly higher, and the endo-, mid-, and epi-longitudinal strain (LS), global radial strain (GRS), and endo- and mid-circumferential strain (CS) were significantly lower in DM rats (all p < 0.05). The endo-, mid-, and epi-LS, GRS, endo- and mid-CS were increased in DT rats compared with DM rats (all p < 0.05). Compared with Con rats, CT rats had a significant increase in LVEDD and LVM (all p < 0.05), meanwhile myocardial strains had no significant differences (all p > 0.05). ConclusionLS-STE was a sensitive method to assess subclinical myocardial changes in T2DM rats. MIAT had the benefit of reversing cardiac systolic subclinical dysfunction in T2DM rats.

A systematic UHPLC-Q-TOF-MS/MS-based strategy for analysis of chemical constituents and related in vivo metabolites of Buyang Huanwu decoction

Ethnopharmacological relevanceBuyang Huanwu Decoction (BYHWD), a traditional Chinese medicine, is one of the classic prescriptions for the treatment of ischemic stroke in clinical practice. It has the effects of tonifying qi, activating blood circulation, and promoting meridian circulation. However, its chemical analysis has not been clarified, which greatly hinders its further clinical application. Therefore, it is necessary to clarify the chemical constituents and metabolites profile of BYHWD in vivo. Aim of the studyCharacterizing the chemical basis of BYHWD in vitro, and combing studies of related metabolism in vivo to screen out the potential active components of BYHWD with pharmacological effects in vivo. Materials and methodsTwelve male rats weighed 200 ± 20 each were selected for the experiments. According to the fragmentation of different structural types of components and diagnostic ions, UHPLC-Q-TOF-MS/MS was used to classify and clarify the unknown components of BYHWD and identify the material basis of BYHWD in vitro. Then, rat plasma, tissues, feces, and urine were collected for analysis. Based on the similarity of MS responses (accurate molecular weight and secondary fragmentation) and chromatographic behavior (retention time), the in vivo prototype and metabolites were analyzed. Through the phase I and phase II metabolism law, a metabolite library was established to analyze the prototype-matched metabolites. ResultsA total of 121 in vitro compounds and 55 in vivo prototypes of BYHWD were identified, corresponding to 123 matched prototypes. It was mainly composed of flavonoids, triterpene saponins, nucleosides and lactones both in vitro and in vivo. Quercetin, ligustilide, astragaloside IV, calycosin, paeoniflorin and ferulic acid were the main prototypes and metabolites in plasma and urine. ConclusionQuercetin, ligustilide, astragaloside IV, calycosin, paeoniflorin and ferulic acid were the main active ingredients of BYHWD.

Emulsion Structural Remodeling in Milk and Its Gelling Products: A Review.

The fat covered by fat globule membrane is scattered in a water phase rich in lactose and milky protein, forming the original emulsion structure of milk. In order to develop low-fat milk products with good performance or dairy products with nutritional reinforcement, the original emulsion structure of milk can be restructured. According to the type of lipid and emulsion structure in milk, the remolded emulsion structure can be divided into three types: restructured single emulsion structure, mixed emulsion structure, and double emulsion structure. The restructured single emulsion structure refers to the introduction of another kind of lipid to skim milk, and the mixed emulsion structure refers to adding another type of oil or oil-in-water (O/W) emulsion to milk containing certain levels of milk fat, whose final emulsion structure is still O/W emulsion. In contrast, the double emulsion structure of milk is a more complicated structural remodeling method, which is usually performed by introducing W/O emulsion into skim milk (W2) to obtain milk containing (water-in-oil-in-water) W1/O/W2 emulsion structure in order to encapsulate more diverse nutrients. Causal statistical analysis was used in this review, based on previous studies on remodeling the emulsion structures in milk and its gelling products. In addition, some common processing technologies (including heat treatment, high-pressure treatment, homogenization, ultrasonic treatment, micro-fluidization, freezing and membrane emulsification) may also have a certain impact on the microstructure and properties of milk and its gelling products with four different emulsion structures. These processing technologies can change the size of the dispersed phase of milk, the composition and structure of the interfacial layer, and the composition and morphology of the aqueous phase substance, so as to regulate the shelf-life, stability, and sensory properties of the final milk products. This research on the restructuring of the emulsion structure of milk is not only a cutting-edge topic in the field of food science, but also a powerful driving force in promoting the transformation and upgrading of the dairy industry to achieve high-quality and multi-functional dairy products, in order to meet the diversified needs of consumers for health and taste.

Structural, electronic, optical, mechanical, and phononic bulk properties of tetragonal trirutile antimonate MSb2O6 (M = Fe, Co, Ni, or Zn): a first-principles prediction for optoelectronic applications

Abstract This work does an extensive analysis of the optoelectronic and mechanical properties of the tri rutile structure type 3d transition metal Antimonate MSb2O6 (M = Fe, Co, Ni, or Zn), for the first time, utilizing the pseudo-potential plane wave approach within the density functional theory framework. When calculating the structural, optical, and mechanical properties, the exchange-correlation interactions were studied using the GGA-PBE functional, whereas when computing electronic, it is analyzed using the HSE06 hybrid functional. The equilibrium lattice parameters exhibit good agreement with the available experimental results. The electronic properties were estimated using the GGA-PBE and HSE06 functionals. Based on the calculated electronic properties with the GGA-PBE functional, the FeSb2O6, CoSb2O6, and NiSb2O6 materials exhibit metallic behavior with energy gap values of 0 eV, while ZnSb2O6 is a semiconductor with a narrow direct band gap (Γ-Γ) of 0.5 eV. Furthermore, the computed band gaps using the HSE06 functional are 0 eV, 0 eV, 1 eV (Γ-Γ), and 4 eV (Γ-Γ) for FeSb2O6, CoSb2O6, NiSb2O6, and ZnSb2O6, respectively. Density of states diagrams were used to gain deeper insights into the characteristics of the energy bands. The optical properties of these compounds, such as the dielectric function, energy loss function, conductivity, reflectivity, refractive index, and absorption coefficient were investigated over the energy range of 0 to 40 eV. The materials exhibited a high absorption coefficient and a significantly low reflectivity within the UV-Vis energy spectrum. The negative cohesive energy Ecoh implies the chemical (thermodynamic) stability of the trirutile MSb2O6 (M = Fe, Co, Ni, or Zn). Mechanical stability is confirmed by applying the Born stability criteria using elastic constants (Cij). The absence of imaginary frequencies in the phonon spectrum calculations confirms the dynamic stability of the studied compounds. These results are consistent with previous experimental research on these materials in photocatalysis and gas sensor applications. On the other hand, these compounds possess exceptional high and broad optical absorption UV range, making them suitable for use in next-generation ultraviolet photodetectors.

Study on the performance of flat-plate collectors with a bottom-mounted non-tracking broken line type reflector

The current flat-plate collectors commonly utilize non-tracking reflectors, primarily in a flat configuration, which is not optimal because it has a large reflection loss at varying solar altitude angles. Broken line type structures have been proven to exhibit better light concentration effects. However, existing research has focused solely on broken line type reflector installed at the top of the collector, leaving a gap in the study of broken line type reflector installed at the bottom. This paper investigates this aspect. Mathematical models for the performance analysis of collectors with/without bottom-mounted reflectors are established. The accuracy of the models is verified using the light tracing software, TracePro. The study includes the simulation analyses of the collector's performance and reflection losses under different conditions. The results indicate that the plate type reflector and broken line type reflector increase the heat collection by 27.92 % and 34.4 %, respectively. So the reflector can make the collector effectively operate in a wider range of ambient temperatures and radiation intensity. Increasing the horizontal length of the collector or adopting a series arrangement can effectively reduce reflection losses. This study provides theoretical guidance for the optimization design of flat-plate collectors with bottom-mounted broken line type reflectors.