Low Figure Research Articles

Achieving high breakdown strength and figure of merit of Ba0.6Sr0.4TiO3 films through coating a Y3Fe5O12 layer

Low tunability and figure of merit significantly limited the application of Ba0.6Sr0.4TiO3 (BST) ferroelectric film, which originates from the low electric breakdown strength and high dielectric loss of BST layer. Garnet structured Y3Fe5O12 (YIG) exhibits the merits of good microwave dielectric property and a much high resistivity, which are helpful for enhancing the breakdown strength and suppressing the dielectric loss. In this work, Y3Fe5O12/Ba0.6Sr0.4TiO3 (YIG/BST) composite films were fabricated via chemical solution deposition method. The composite films exhibited a low dielectric loss (0.006) and an almost frequency independent dielectric constant in a frequency range from 10 kHz to 1 MHz. The electric breakdown strength was significantly enhanced from less than 400 kV/cm to around 800 kV/cm through coating a YIG layer, causing an excellent tunability of 72.84% and an ultra-high figure of merit (FOM=118) at 800 kV/cm in YIG/BST film. It is physically clarified that the conduction loss plays an important role in BST film while the intrinsic loss is the dominate factor for the YIG/BST composite films.

Analysis of appeals of patients with sensorineural hearing loss to the otolaryngological department during 2015-2021

Patients with perceptual hearing impairment occupy a significant place among patients of the otolaryngology department. They often have psycho-emotional disorders, social and family disorders. It is important to understand the etiopathogenesis of the disease. Some cases of sensorineural hearing loss (SHL) remain with an unknown etiopathogenetic mechanism of development, which requires more in-depth examination of patients. Aim: to analyze the number and character of appeals of patients with sensorineural hearing impairment to the otolaryngology department of the Alexander Clinical Hospital in Kyiv during 2015-2021. Methods and materials: We analysed 13,147 inpatients 'medical records, from which 1,138 patients' cards with perceptual hearing impairments were selected. Results: According to the analysis, the absolute and relative number of patients in the otolaryngology department of Alexander Clinical Hospital in Kyiv in 2020 and 2021 decreased significantly due to the temporary re-profiling of the otolaryngology department in these years for infectious patients with COVID-19. The most common changes in bone conduction according to audiometry occurred against the background of acute or exacerbation of chronic otitis media (509 cases). But this figure may be due to inflammatory changes, rather than true sensorineural hearing loss. 155 patients could not name a specific cause. These patients required further in-depth examination. In the third most frequent place indicated hypothermia, acute respiratory diseases (135 cases). In 106 patients, acute sensorineural hearing loss was caused by vascular disorders, and 11 patients reported emotional stress as the cause. Acute trauma caused perceptual disorders in 16, surgery in 3, neuroma in 1, barotrauma and rupture of the tympanic membrane in 7, the use of chemotherapy in 3 cases. The average interval between the onset of the first symptoms of SHL and hospitalization in the otolaryngology department of the Alexander Clinical Hospital in Kyiv for 2025-2021 was 8.19 days. The lowest interval was in 2016 – 7.5 days, the largest – 10 days in 2021. The average duration of inpatient treatment of patients for 2015-2021 was 9.4 days. The lowest figure was in 2020 – 8.1 days, the highest – 10.4 days in 2021. There were 495 patients with bilateral lesions and 354 patients with left lesions, 289 patients had lesions on the right side. 39 patients with SHL and type 2 diabetes mellitus had diabetes, 460 had tinnitus and 44 had vestibular disorders. Conclusions: Patients with acute sensorineural hearing loss receive inpatient treatment in the otolaryngology department than with the progression or exacerbation of the chronic form. Otitis media and acute respiratory diseases were the most common disorders of bone conduction, but not all of these cases can be interpreted as sensorineural hearing loss. The average interval for the study period between the onset of the first symptoms and the start of treatment was 8.19 days, which exceeds the recommended time of this indicator. The average duration of inpatient treatment was 9.4 days and did not change significantly during the study period.

Relationship of Work-Related Stress and Offline Social Leisure on Political Participation of Voters in the United States

In the United States (US), citizens’ political participation is 15%. Contemporary psychological models explaining political participation are based on education and socioeconomic status, which are unable to explain the overall low political participation figures. The study suggests a holistic approach, with two societal tendencies: increasing work-related stress and diminishing offline social leisure, together with a mediating effect of participatory efficacy to assess associations with the political participation of US voters. The quantitative correlational study uses structural equation modelling (SEM) analysis on the General Social Survey representative sample of US voters (N = 295, Mage = 44.49, SD = 13.43), controlled for education and socioeconomic status. Work-related stress was not significantly associated with political participation (β = 0.08, p = 0.09). Offline social leisure was positively associated with political participation (β = 0.28, p < 0.001). The mediating effect of participatory efficacy on the relationship between offline social leisure and political participation was positive and significant (β = 0.05, p < 0.001). Additional analyses, regression and SEM on the European Social Survey sample (N = 27,604) boosted internal and external validity. Results indicate that offline social leisure is more predictive than education and socioeconomic status, showing that examining societal trends leads to a better understanding of political participation.

Design and optimization of three-dimensional composite multilayer cylindrical pentamode metamaterials for controlling low frequency acoustic waves

For three-dimensional pentamode metamaterials, it is of great significance to realize underwater low frequency acoustic wave control. Therefore, in order to compare with traditional double-cone pentamode metamaterials, two multilayer composite cylindrical three-dimensional pentamode metamaterials with low frequency and broad band gaps are proposed in this paper. By using pentamode metamaterials with lattice constants on the order of centimeters, the phononic band gaps below 60 Hz and the single-mode area below 30 Hz can be obtained. In addition, compared with asymmetrical double-cone locally resonant pentamode metamaterials, the lower edge frequency, relative bandwidth and figure of merit of the first phononic band gap can be reduced by up to 61.4%, 10.3% and 40.6%, respectively. It will provide reference and guidance for the engineering application of pentamode metamaterials in controlling the ultra-low frequency broadband acoustic waves, vibration and noise reduction.

지역별 소득규모와 운송거리를 고려한 물류부동산 입지 평가에 관한 탐색적 연구*

This study intends to make a quantitative evaluation of the location of logistic real estate from the perspective of total transportation costs on administrative districts (dong, eup and myeon) in Korea. The analysis targeted 5,002 dongs or myeons nationwide at the end of 2019, which marked a national minimum space unit. Total transportation cost, which is equal to a key factor, was calculated by the market volume and the network distance. The main findings of the study are briefly summarized as follows: First, the areas with low figures about total transportation costs were mainly concentrated on Seoul metropolitan area (SMA) including the souths of Seoul and Gyeonggi Province and Incheon. Among them, the total transportation cost in Gyeonggi province was indiscriminately distributed in each region. Second, the distribution of total transportation costs is relatively similar to locations of logistics centers with large supply, indicating that supply is efficiently arranged in the national spatial structure. In addition, according to the outcome of regression analysis having land prices as a dependent variable, total transportation costs were verified as a statistically significant factor. Third, since the supply is limited due to differences in land prices and policy operation by regions, the distribution disparity between supply volumes and total transportation costs suggested the possibility that there could be different from the characteristics for the supply of logistics markets, rental costs and owners of goods. In conclusion, these data through ArcGIS tool can be useful for decision- making in choosing optimal locations of logistic real estate within limited budget constraints for participants (e.g. policy makers, investors, landlords and tenants) in the future.

IDF21-0566 Adherence to Foot and Eye exams Among People Living with Diabetes in Nigeria

Background: Adverse outcomes of diabetes such as diabetic foot gangrene and diabetic retinopathy are often as a result of poorly controlled glycemia and late detection of early signs of complications. But even where people are informed about these complications of diabetes, there is sparse data in Nigeria on whether patients with diabetes undergo routine foot and eye exams. mDoc is a digital health social enterprise which provides virtual self-care support to people living with regular and chronic health conditions including diabetes through our CompleteHealth™ platform. In our service provision, we see many members with diabetes and noticed that only a few of them reported having eye or foot exams. This presentation describes how we surveyed members to get a clear picture of their adherence to foot and eye exams in Nigeria. Aim: To examine adherence to foot and eye exams among people living with diabetes in Nigeria, using a digital self-care platform. Method: This was a survey conducted on members with diabetes registered on the mDoc CompleteHealth™ platform between September 2020 and August 2021. After onboarding, members were provided with self-care support through the mDoc’s virtual omni-channel support system: weekly messages were sent via CompleteHealth™ to members and the coach-led multidisciplinary care teams (including a nutritionist and fitness coach). They were provided with lifestyle modifications on diet and exercise as well as self-care education on diabetes management and the importance of foot and eye care. Also, they received advice on regular blood glucose levels checks and medication adherence. Members could also enter and track their health metrics via the CompleteHealth™ platform. The survey was administered by the health coach who called members to offer self-care guidance and advice on diabetes management. The members were asked if they had undergone a foot and/or an eye exam in the 12 months preceding the survey. Afterwards, data was collected via CompleteHealth™ for the analysis. Results: 103 members were contacted as part of the survey. Of these, 77 members responded at the time of calling. All 77 members responded to the first question regarding adherence to foot care. Of these, only 8 (10.5%) had undergone a foot exam in the preceding year. 71 members responded to the second question regarding adherence to eye care, and of these 16 (22.5%) answered “yes” indicating they had done one. Discussion: Our study showed that despite educating people with diabetes on the importance of foot and eye care and providing them with self-care support, there was low adherence to foot and eye exams. Although there was a general decrease in the average fasting blood glucose among members with diabetes of the platform (there was a reduction of 19 mg/dL among members over the same period), it is alarming to see such low adherence figures. While education on the control of diabetes is an important tool in reducing the incidence of retinopathy and foot complications, there is also a need to increase access to foot and eye care which is low across Africa.

Green Corridors May Sustain Habitats for Earthworms in A Partially Converted Grassland

Permanent grasslands provide a healthy and undisturbed environment. We investigated how mulching altered the soil physicochemical parameters, earthworm abundance, biomass, species composition and vegetation cover compared to grassland and cultivated alfalfa field. Microplots (2 × 2 m) were mulched with either weed control fabric (WF) alone or WF combined with straw (WF + S) on a grassland to grow tomato in Ősagárd (Nógrád county, Hungary) between 2018 and 2021. We had two other microhabitats: a conventionally cultivated alfalfa field (CA) and grassland (GR). We measured soil parameters (physical: soil moisture content (SMC), soil penetration resistance (SPR); chemical: pH, soil organic matter; and biological: earthworm abundance, biomass, species composition and vegetation). SMC was significantly higher on covered plots (WF; WF + S) compared to CA and GR. SPR values were the highest in CA and GR at 20 cm depth. The abundance and biomass of earthworms were the highest in GR and lowest in CA in all seasons. Plant abundance was highly influenced by season and habitat. Despite the higher compaction and lower SMC figures, grass vegetation still provided a more suitable environment for earthworms than mulched plots (WF, WF + S). Therefore, where there is agricultural production on grassland, we suggest leaving uncultivated and uncovered patches as biodiversity corridors.

Theory of drain noise in high electron mobility transistors based on real-space transfer

High electron mobility transistors are widely used as microwave amplifiers owing to their low microwave noise figure. Electronic noise in these devices is typically modeled by noise sources at the gate and drain. While consensus exists regarding the origin of the gate noise, that of drain noise is a topic of debate. Here, we report a theory of drain noise as a type of partition noise arising from real-space transfer of hot electrons from the channel to the barrier. The theory accounts for the magnitude and dependencies of the drain temperature and suggests strategies to realize devices with lower noise figure.

The SiPb monolayer with high thermoelectric performance at room temperature

The SiPb monolayer with low lattice thermal conductivity and high dimensionless figure of merit (ZT) is identified by the first-principles calculations. The geometrical configuration is optimized, and the stabilities are confirmed with phonon dispersion and ab initio molecular dynamics simulation. The effective mass, mobility, and relaxation time are calculated by using the deformation theory. Based on the semiclassical Boltzmann transport theory and the band alignment by the Heyd-Scuseria-Ernzerhof hybrid functional, the Seebeck coefficient, electrical conductivity, power factor, and electron thermal conductivity relative to the carrier and temperature are obtained, while the ZT dependent on temperature is envaulted with the bipolar effect. The obtained ZT of 0.666/0.907 in the x/y-direction at 310 K supports the SiPb monolayer as a very promising application in implantable bioelectronics and wearable electronics.

Bipolar conduction asymmetries lead to ultra-high thermoelectric power factor

Low bandgap thermoelectric materials suffer from bipolar effects at high temperatures, with increased electronic thermal conductivity and reduced Seebeck coefficient, leading to a reduced power factor and a low ZT figure of merit. In this work we show that the presence of strong transport asymmetries between the conduction and valence bands can allow high phonon-limited electronic conductivity at finite Seebeck coefficient values, leading to largely enhanced power factors. The power factors that can be achieved can be significantly larger compared to their maximum unipolar counterparts, allowing for doubling of the ZT figure of merit. We identify this behavior in low-bandgap cases from the half-Heusler material family. Using both advanced electronic Boltzmann transport calculations for realistic material band structures and model parabolic electronic bands, we elaborate on the parameters that determine this effect. We then develop a series of descriptors that can guide machine learning studies in identifying such classes of materials with extraordinary power factors at nearly undoped conditions. For this we test more than 3000 analytical band structures and their features, and more than 120 possible descriptors, to identify the most promising ones that contain: (i) only band structure features for easy identification from material databases and (ii) band structure and transport parameters that provide much higher correlations, but for which parameter availability can be somewhat more scarce.

Enhanced performance of Bi2Te3-based thermoelectric materials by incorporating Bi2Fe4O9 magnetic nanoparticles

Thermoelectric (TE) materials have been extensively investigated to solve the energy crisis and alleviate environmental pollution. Currently, n-type and p-type Bi2Te3 based are the only commercialized TE materials. However, their application has been severely limited by the low TE figure of merit (ZT) of p-type Bi2Te3-based TE materials. Here, we demonstrate that the TE performance of p-type materials could be improved by incorporating Bi2Fe4O9 magnetic nanoparticles. Bi2Fe4O9 magnetic nanoparticles could effectively scatter low-energy carrier and improve the carrier quality. The synergistic effect of boundary scattering and magnetic particles scattering lead to the increase of Seebeck coefficient and decrease of thermal conductivity. Finally, the maximum ZT value 1.1 is obtained at 393 K, which is 13% higher the pure sample. The average ZT value of the nanocomposite consisting Bi2Fe4O9 magnetic nanoparticles is 0.98 in the temperature range of 303–483 K, exhibiting an increase of 11%. Overall, the results indicate that magnetic nanoparticles with low saturation magnetic moment have positive effect on the performance of TE materials.

Flexible elemental thermoelectrics with ultra-high power density

Flexible thermoelectrics have attracted great attention due to their potential to convert waste heat to electricity to power wearable devices and IoT (Internet of things) sensors. Though organic thin-film thermoelectric materials are popular choice for preparing flexible thermoelectrics, they suffer from low thermoelectric performances due to the low figure of merit zT. In this work, we demonstrate a new strategy to design high-performance thermoelectrics by highlighting the influence of power factors instead of zT. To verify our claim, thermoelectric is prepared through sputtering high-power factor but low zT elemental thin films of Sb (p-type) and Ni (n-type) on a polyimide substrate. In this system, ascribed by the high-power factor (up to 7 mW/mK2), a high power density of up to 4.7 mW/cm2 at a temperature gradient of 50 K can be achieved, even with the low zT (<0.1). In addition, finite element method (FEM) analysis shows that the benefit of high-power factor increases with decreasing film thicknesses. Our results show that in the case of organics and inorganics thin films, maximizing power factor is more important than maximizing zT. This finding serves to guide the design paradigm of thermoelectrics for wearable devices and is useful for the broad organic electronics community.

MEASUREMENT OF VOLUNTARY REPORTING PRACTICES IN EMERGING MARKETS

Financial reports are widely regarded as the basis for evaluating companies, as users heavily rely on them when making various decisions. Financial reports are prepared under a wide range of criteria, both internationally and locally. Moreover, interest in this area has increased in the aftermath of the collapse of several major companies. In the United States of America, this resulted in significant financial problems for insurance firms and stockholders, affecting the overall economic condition. The purpose of this research is to determine the degree of voluntary disclosure by examining the financial statements of a sample of businesses listed on the Iraqi Stock Exchange for the year 2015. The study sample included (58) firms listed on the primary market, with a market capitalization of (82 percent ). a scale consisting of (110) items has been developed To quantify the degree of Voluntary disclosure. According to the study's ranking, the average proportion of voluntary information sharing was 31.6 percent, a low figure. The research suggested that interest in voluntary disclosure be increased due to its critical role in broadening the definition of the business, attaining information symmetry, and attracting investments

MRI-assessed tumor-free distance to serosa predicts deep myometrial invasion and poor outcome in endometrial cancer

ObjectivesTo explore the diagnostic accuracy of preoperative magnetic resonance imaging (MRI)-derived tumor measurements for the prediction of histopathological deep (≥ 50%) myometrial invasion (pDMI) and prognostication in endometrial cancer (EC).MethodsPreoperative pelvic MRI of 357 included patients with histologically confirmed EC were read independently by three radiologists blinded to clinical information. The radiologists recorded imaging findings (T1 post-contrast sequence) suggesting deep (≥ 50%) myometrial invasion (iDMI) and measured anteroposterior tumor diameter (APD), depth of myometrial tumor invasion (DOI) and tumor-free distance to serosa (iTFD). Receiver operating characteristic (ROC) curves for the prediction of pDMI were plotted for the different MRI measurements. The predictive and prognostic value of the MRI measurements was analyzed using logistic regression and Cox proportional hazard model.ResultsiTFD yielded highest area under the ROC curve (AUC) for the prediction of pDMI with an AUC of 0.82, whereas DOI, APD and iDMI yielded AUCs of 0.74, 0.81 and 0.74, respectively. Multivariate analysis for predicting pDMI yielded highest predictive value of iTFD < 6 mm with OR of 5.8 (p < 0.001) and lower figures for DOI ≥ 5 mm (OR = 2.8, p = 0.01), APD ≥ 17 mm (OR = 2.8, p < 0.001) and iDMI (OR = 1.1, p = 0.82). Patients with iTFD < 6 mm also had significantly reduced progression-free survival with hazard ratio of 2.4 (p < 0.001).ConclusionFor predicting pDMI, iTFD yielded best diagnostic performance and iTFD < 6 mm outperformed other cutoff-based imaging markers and conventional subjective assessment of deep myometrial invasion (iDMI) for diagnosing pDMI. Thus, iTFD at MRI represents a promising preoperative imaging biomarker that may aid in predicting pDMI and high-risk disease in EC.

Spectral image contrast-based flow digital nanoplasmon-metry for ultrasensitive antibody detection

BackgroundGold nanoparticles (AuNPs) have been widely used in local surface plasmon resonance (LSPR) immunoassays for biomolecule sensing, which is primarily based on two conventional methods: absorption spectra analysis and colorimetry. The low figure of merit (FoM) of the LSPR and high-concentration AuNP requirement restrict their limit of detection (LOD), which is approximately ng to μg mL−1 in antibody detection if there is no other signal or analyte amplification. Improvements in sensitivity have been slow in recent for a long time, and pushing the boundary of the current LOD is a great challenge of current LSPR immunoassays in biosensing.ResultsIn this work, we developed spectral image contrast-based flow digital nanoplasmon-metry (Flow DiNM) to push the LOD boundary. Comparing the scattering image brightness of AuNPs in two neighboring wavelength bands near the LSPR peak, the peak shift signal is strongly amplified and quickly detected. Introducing digital analysis, the Flow DiNM provides an ultrahigh signal-to-noise ratio and has a lower sample volume requirement. Compared to the conventional analog LSPR immunoassay, Flow DiNM for anti-BSA detection in pure samples has an LOD as low as 1 pg mL−1 within only a 15-min detection time and 500 μL sample volume. Antibody assays against spike proteins of SARS-CoV-2 in artificial saliva that contained various proteins were also conducted to validate the detection of Flow DiNM in complicated samples. Flow DiNM shows significant discrimination in detection with an LOD of 10 pg mL−1 and a broad dynamic detection range of five orders of magnitude.ConclusionTogether with the quick readout time and simple operation, this work clearly demonstrated the high sensitivity and selectivity of the developed Flow DiNM in rapid antibody detection. Spectral image contrast and digital analysis further provide a new generation of LSPR immunoassay with AuNPs.Graphical

Comparative evaluation of shaping ability of sequential rotary, single rotary, and single reciprocating file systems in simulated curved canals using cone-beam computed tomography: An in vitro study

Comparative evaluation of shaping ability of sequential rotary, single rotary, and single reciprocating file systems in simulated curved canals using cone-beam computed tomography: An in vitro study

Newer tools to assess socioeconomic status of Indian households.

“Let there be no distinction between rich and poor, high and low.” – The Collected Works of Mahatma Gandhi, Publications Division XXVI – 199 Dear Editor, Ananthan in May 2021 issue of the Journal highlights modified Kuppuswamy scale for (measuring) socioeconomic status of an Indian family – Update based on new CPI (IW) series from September 2020 (data). Recently Labour Bureau, Government of India revised base year of existing CPI (IW) series from 2001 to 2016 and this letter updates the income ranges for Modified Kuppuswamy scale on this basis.[1] Notwithstanding what effect the economic revision will have on assessing socioeconomic status of an Indian family, we disagree with the basic assumption that this status is one of the most important determinants of health status of a family. If we look at current status of various States of our nation, there is a hidden lesson in relationship (or its lack) between average income per person (Net State domestic Product) and various health indicators. National Institute for Transforming India (NITI Aayog) – a government body – in collaboration with World Bank released Healthy States – Progressive India, which has a Report on the Ranks of States and Union Territories, two years ago. The Report counts on as basic health services indicators as vacancy of Medical Officers at PHCs and of Specialists at District Hospitals, proportion of functional 24 × 7 PHCs and proportion of ANC registered within first trimester against total registrations etc., It has a Figure E1 – Larger States: Incremental scores and ranks with overall performance on page 17. What this figure highlights is that Kerala is the best overall performer in ensuring welfare of its citizens, whereas richer ones like Karnataka and Telangana lag behind. Similarly, Figure E.4 on page 21 of the Report provides us a relationship between composite Health index score (a measurement of health indicators) and per capita State Domestic Product (for income). If health indicators are simple products of income, the relationship should be linear. But surprisingly that is not the case. States higher on the y axis are better social performers where Kerala tops the graph. What is striking to observe is that several other States – despite having similar wealth fare – not as good as this one. We need to learn a simple lesson from this official report[2] and others[3] that higher funds don’t automatically translate into indicators for making our lives better and much complexities exist in between. Another basic indicator of health of a society is that how many women die during childbirth. Here UNICEF provides an updated map of maternal mortality ratio.[4] When we look at it, what is obvious is that Thailand, Sri Lanka. Malaysia and Vietnam have very low figures whereas they don’t have much higher income per person than us. Hence we learn while looking around is that relationship between economic status and health indicators is complex one and several factors, for example improvement of primary and preventive care as well as providing universal basic education play a strong intermediate role to decide final outcome. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. We accessed all the webpages while submitting this letter to the Editor.

Seroprevalence against Toscana virus in Spain: The case of the autonomous community of Madrid.

The Toscana virus (TOSV) is a neurotropic arbovirus that is transmitted through the bite of some Phlebotomus species. In 2009, the largest outbreak of leishmaniasis described so far in Europe, occurred in the Autonomous Community of Madrid, Spain, which was related to the population increase of P. perniciosus in this region. A seroprevalence study was conducted to determine the circulation of TOSV among the population of this geographic area. A total of 516 sera were collected in two different stages: 2007 (before the leishmaniasis outbreak) and 2018-19 (representative of the current situation). In the sera, presence of IgG antibodies against TOSV was determined by commercial ELISA. The overall seroprevalence was 34.5%. The anti-TOSV IgG level was significantly higher in the samples collected in 2007 (41.5%) than 2018-19 (27.3%). The results of this study show a very active TOSV circulation in the region that is greater than expected. The lower seroprevalence figures in 2018-19 may be related to the vector and environmental control measures that were put in place as a result of the leishmaniasis outbreak of 2009. This highlights the importance of such strategies to reduce the incidence of TOSV infection and other vector-borne diseases.

Improving thermoelectric performance of GeSe compound by crystal structure engineering

In the thermoelectric field, GeSe is a two-dimensional layered semiconductor with a large band gap, intrinsically low carrier concentration and poor thermoelectric figure of merit &lt;i&gt;ZT&lt;/i&gt;. In this work, a series of GeSe&lt;sub&gt;1–&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt;Te&lt;sub&gt;&lt;i&gt;x&lt;/i&gt;&lt;/sub&gt; (&lt;i&gt;x&lt;/i&gt; = 0, 0.05, 0.15, 0.25, 0.35, 0.45) polycrystalline samples is prepared by melting and quenching combined with spark plasma activation sintering process. The influences of Te content on the phase structure and thermoelectric transport properties of GeSe are systematically studied. The results indicate that with the increase of Te content, the crystal structure of GeSe gradually changes from orthorhombic to rhombohedral structure. This reduces the band gap of the material, and simultaneously increases the carrier concentration and mobility. Meanwhile, the energy band degeneracy of the compound increases significantly because of enhanced crystal symmetry in this process, thereby considerably improving the effective mass of carriers. Altogether, the power factor of the rhombohedral GeSe is increased by about 2 to 3 orders of magnitude compared with that of the orthorhombic phase GeSe. In addition, the rhombohedral phase GeSe has abundant cationic vacancy defects and softened phonons arising from its ferroelectric feature, leading the lattice thermal conductivity to be 60% lower than orthorhombic one. The GeSe&lt;sub&gt;0.55&lt;/sub&gt;Te&lt;sub&gt;0.45&lt;/sub&gt; sample achieves a peak &lt;i&gt;ZT&lt;/i&gt; of 0.75 at 573 K, which is 19 times that of pristine GeSe. Crystal structure engineering could be considered as an effective way of improving the thermoelectric performance of GeSe compounds.

High-quality Finishing Process for Silicon Carbide Optical Components Using Conventional Equipment

The development of low-cost high quality surface finishing methods for silicon carbide (SiC) is an arduous task. Nowadays, the SiC mirrors manufacture involves extensive, complex, and costly finishing processes carried out on highly expensive ultra-precise machines. In this work, a cost-effective surface finishing method has been successfully developed, using conventional machines for the optical finishing of SiC. The results showed that the combination of ductile grinding and polishing in conventional low-cost machines allowed to obtain high-quality surface finish on SiC substrates with low roughness (4 - 10 nm Ra ) and optical figure in the range λ / 4 - λ / 8, at a reduced 32 hours total processing time.