Low Coefficient Research Articles

Time In Tight Range in children and adolescents with type 1 diabetes: A cross-sectional observational single centre study evaluating efficacy of new advanced technologies.

Early and tight glycaemic control is crucial to prevent long-term complications of Type 1 Diabetes (T1D). The aim of our study was to compare glucose metrics, including Time In Tight Range (TITR), in a real-world setting. We performed a single-centre cross-sectional study in 534 children and adolescents with T1D. Participants were divided into four groups (multiple daily injections+real-time Continuous glucose monitoring (CGM), multiple daily injections+intermittently scanned CGM, sensor augmented pump (SAP), and Advanced Hybrid Closed-Loop (AHCL). Demographical and clinical data were collected and analysed. The group with AHCL showed significantly higher Time In Range (TIR) (71.31%±10.88) than SAP (57.82%±14.98; p<0.001), MDI+rtCGM (54.56%±17.04; p<0.001) and MDI+isCGM (52.17%±19.36; p<0.001) groups with a lower Time Above Range (p<0.001). The group with AHCL also showed lower Time Below Range than MDI+isCGM and SAP groups (p<0.01). The overall TITR was 37%±14 with 19% of participants who reached a TITR ≥50% with a mean TIR of 81%. AHCL had significantly higher TITR (45.46%±11.77) than SAP (36.25%±13.53; p<0.001), MDI+rtCGM (34.03%±13.89; p<0.001) and MDI+isCGM (33.37%±15.84; p<0.001) groups with a lower Coefficient of Variation (p<0.001). Our study indicates that AHCL ensures a better glycaemic control with an improvement in both TIR and TITR, along with a reduction in CV. Implementation of automated insulin delivery systems should be considered in the treatment of children and adolescents with T1D.

First-Principles Study on Polymer Electrolyte Interface Engineering for Lithium Metal Anodes.

Modifying the interface between the lithium metal anode (LMA) and the electrolyte is crucial for achieving high-performance lithium metal batteries (LMBs). Recent research indicates that altering Li-metal interfaces with polymer coatings is an effective approach to extend LMBs' cycling lifespan. However, the physical properties of these polymer-Li interfaces have not yet been fully investigated. Therefore, the structural stability, electronic conductivity, and ionic conductivity of polymer-Li interfaces were examined based on first-principles calculations in this study. Several representative polymer compounds utilized in LMBs were assessed, including polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and polyethylene oxide (PEO). Our research revealed that lithium fluoride is formed upon fluoropolymer degradation, explaining previously observed experimental results. Polymers containing nitrile groups exhibit strong adhesion to lithium metal, facilitating the formation of the stable interface layer. Regarding electronic conductivity, the fluoropolymers preserve a good insulating property, which diminished marginally in the presence of lithium, but that of PAN and PEO significantly reduces. Additionally, lithium diffusion on PTFE and PEO demonstrates low diffusion barriers and high coefficients, enabling easy transportation. Overall, our investigation reveals that the interfaces formed between various polymers and LMA have distinct characteristics, providing new fundamental insights for designing composites with tailored interface properties.

Is transvaginal mesh surgery with polytetrafluoroethylene mesh ORIHIME® feasible for anterior pelvic organ prolapse?-Randomized comparative study between ORIHIME® and Polyform™.

Transvaginal mesh surgery for pelvic organ prolapse has been widely performed in Japan, but polypropylene mesh has not been used in Japan since the banon TVM using polypropylene mesh in the United States. Currently, polytetrafluoroethylene mesh ORIHIME® is the only mesh available for TVM in Japan. Although polytetrafluoroethylene is a safe material, its low coefficient of friction and insufficient adhesion to the surrounding tissue make it difficult to maintain the mesh position when it is used in the transvaginal mesh surgery. The aim of this study was to evaluate the feasibility of TVM-A2 using ORIHIME®. One hundred cases of TVM-A2 were included in the study. The patients were randomly assigned to two groups: the ORIHIME® group (Group O) and the PolyformTM group (Group P). With 50 patients in each group, the complications and recurrences up to the fourth year were compared. Surgeries were performed using the TVM-A2 method. Statistical analysis was performed using EZR. There were no significant differences in baseline parameters between the two groups. We observed no perioperative complications, and saw one case of postoperative abscess formation in Group O, which resolved successfully after incision and drainage. The 4-year recurrence rate was significantly higher in Group O. As the recurrence rate was significantly higher in Group O, we conclude that TVM-A2 using ORIHIME® which is the same procedure as TVM-A2 using polypropylene mesh is not feasible in repairing the pelvic organ prolapse.

Sintering Behavior and Thermal Properties of Cu-Graphite Materials by a Spark Plasma Sintering Method

The use of heat dissipation materials in various field such as power semiconductor device, LED and microelectronic system. Therefore, there is a need for heat dissipation materials using copper (Cu) and graphite (Gr). These materials have high thermal conductivity. In particular, graphite has high thermal stability with a low coefficient of thermal expansion. This study was conducted to enhance the thermal properties of Cu for use in heat dissipation materials, using a spark plasma sintering method. Cu-Gr powders were mixed by a shaking mixer and fabricated with volume fractions of 7:3, 6:4, 5:5, 4:6 and 3:7. The spark plasma sintering method is a uniaxial pressurization process, which can control the direction of Gr. The Cu-Gr powders were sintered at a temperature of 850 oC at a heating rate of 30 oC/min and a sintering pressure of 40MPa. Consequently, as the Gr contents were increased, the relative densities of the Cu-Gr composites decreased from 99.25 to 94.85%. Gr has high resistance to high-temperature deformation, which contributed to a decrease in shrinkage and relative density. The highest thermal conductivity was measured at 539.7 W/ m·K for a Cu-Gr volume ratio of 5:5. The thermal conductivity of the directionally controlled Gr was measured to be about 20-30 W/m·K higher than the uncontrolled sample. Furthermore, the TDP (Thermal distortion parameter), for which a lower value indicates better thermal stability, was systematically investigated.

The role of manufacturing-induced texture on the tribological performance of cold work tool steels

Abstract Manufacturing operations produce surface characteristics that, although stochastic, can significantly affect functionality, especially in forming tools, impacting contact and lubrication conditions during operation. This study investigates the influence of stochastic microtextures resulting from milling on the tribological performance of cold work tool steels with two different carbon contents (0.8 and 2 wt%). Different surface textures were observed resulting from the different C contents, with 3D roughness parameters indicating rougher surfaces for the 2.0% wt. C steel. Tribological behavior was assessed using the strip drawing test to analyze friction, wear coefficients, and wear mechanisms. Surface analysis before and after testing was executed employed SEM, EDX, and CLSM, with CLSM also used to determine 3D roughness parameters of the worn tracks. Post-test macrographic analyses and 2D roughness measurements were conducted on the pulled sheets. Tribological test data revealed lower friction and wear coefficients for the 2.0 wt.% C tool steel, with susceptibility to abrasion wear, while the 0.8 wt.% C tool exhibited a higher tendency towards adhesion wear. Post-test analysis suggested smoother surfaces for the 2.0 wt.% C steel compared to the 0.8 wt.% C steel. Macrographic analysis showed no visible wear marks on sheets tested with the 2.0 wt.% C steel, contrasting with wear grooves visible on sheets pulled against the 0.8 wt.% C steel. Additionally, 2D roughness measurements indicated higher roughness after pulling against the 0.8 wt.% C tool compared to the 2.0 wt. C tool. Overall, the study demonstrates that manufacturing-induced textures without the need of post-manufacturing texturing influence the tribological performance of the evaluated steels, opening an avenue to be explored to improve the tribological performance of forming tools.&amp;#xD;

A Compact C-Band Multiple-Input Multiple-Output Circular Microstrip Patch Antenna Array with Octagonal Slotted Ground Plane and Neutralization Line for Improved Port Isolation in 5G Handheld Devices

In this paper, an eight-port antenna array is presented for 5G handheld terminals to support multiple-input multiple-output (MIMO) operations. The reported design involves three layers: the top contains eight circular microstrip feed elements; the middle is a low-cost FR-4 substrate, and the bottom layer is a ground plane with four etched octagonal slots. Each resonating element is fed by 50-ohm sub-miniature connectors. To mitigate the detrimental effects of mutual coupling of ports and enhance overall isolation between the adjacent microstrip-fed circular patch elements, a neutralization line is strategically implemented between the feed lines of the antenna array. The design configuration involves two elements at each vertex of the printed circuit board (PCB). The overall dimensions of the PCB are 150 × 75 mm2. Each slot and its corresponding radiating elements exhibit linear dual polarization and diverse radiation patterns. The proposed antenna design achieves the required operating bandwidth of more than 1000 MHz spanning from 3 to 4.2 GHz, effectively covering all the upper C-band frequency range of 3.3 GHz to 4.2 GHz allocated for 5G n77 and n78 frequency range 1 (FR1). Required port isolation and lower envelop correlation coefficient (ECC) are achieved for the band of interest. The proposed design gives a peak gain of up to 4 dB for the said band. In addition to these results, degradation in the performance of the antenna array is also investigated during different operating modes of the handheld device. Measured results from the fabricated unit cell and whole array also have a good match with simulated results. On the whole, the proposed antenna possesses the potential to be used in 5G and the open radio access network (ORAN) compliant handheld devices.

Gastropods are faced with potential environmental hazards in Kuala Langsa, Aceh

The Kuala Langsa Peninsula is a geographical region that is often developed as a site of habitat. The surrounding nature of Kuala Langsa is an environment of biodiversity that contains gastropods. There are also several mangrove areas throughout Kuala Langsa with certain characteristics, under certain conditions and status, which are ecological or non-ecological conservation. The purpose of this investigation is to determine the level of pollution that occurs in the port of Kuala Langsa by looking at the value of the index of gastropodic diversity. The research uses the quantitative method with the Shannon-Wienner diversity index formula and sampling using the square tranche technique. The results show that diversity from common and detected low quality is based on the total number of species in a community found, as well as very similar types of organisms, resulting in low diversity coefficient values and water quality belonging to moderate pollution. The conclusion is that the total number of gastropods is 1,064 individuals from 9 families and 19 species on the three research locations. It can be concluded that the highest value of the diversity index obtained with the data is at station II, which is 2, whereas the lowest diversity Index value at station III is at 1.86 and is followed by station I at 1.91, as long as from the data the variability index value belongs to the type of moderate polluted waters.

A Study on the Effects of Cementless Total Knee Arthroplasty Implants’ Surface Morphology via Finite Element Analysis

Total knee arthroplasty (TKA) is one of the most commonly performed orthopedic surgeries, with nearly one million performed in 2020 in the United States alone. Changing patient demographics, predominately indicated by increases in younger, more active, and more obese patients undergoing TKA, poses a challenge to orthopedic surgeons as these factors present a greater risk of long-term complications. Historically, cemented TKA has been the gold standard for fixation, but long-term aseptic loosening continues to be a risk for cemented implants. Cementless TKA, which relies on the surface morphology of a porous coating for biologic fixation of implant to bone, may provide improved long-term survivorship compared with cement. The quality of this bond is dependent on an interference fit and the roughness, or coefficient of friction, between the implant and the bonebone. Stress shielding is a measure of the difference in the stress experienced by implanted bone versus surrounding native bone. A finite element model (FEM) can be used to quantify and better understand stress shielding in order to better evaluate and optimize implant design. In this study, a FEM was constructed to investigate how the surface coating of cementless implants (coefficient of friction) and the location of the coating application affected the stress-shielding response in the tibia. It was determined that the stress distribution in the native tibia surrounding a cementless TKA implant was dependent on the coefficient of friction applied at the tip of the implant’s stem. Materials with lower friction coefficients applied to the stem tip resulted in higher compressive stress experienced by implanted bone, and more favorable overall stress-shielding responses.

High-performance microbolometers with metal-insulator-metal plasmonic absorbers in CMOS technology

The practical applications of microbolometers in CMOS technology face challenges since the thermometer layers in microbolometers are typically of low IR absorption coefficients. In this paper, we demonstrate the integration of IR metal-insulator-metal (MIM) plasmonic absorber on the CMOS resistive-type microbolometers to maximize the optical detectivity. The MIM absorbers utilize Al metals and SiO2 dielectric films in the standard CMOS process and the configuration is numerically simulated and analyzed to assess the effectiveness of high IR absorption through propagating surface plasmon (PSP) resonance and localized surface plasmon (LSP) resonance. Experimental results show that the microbolometer integrated with the MIM plasmonic absorber has a 64% improvement in detectivity (D*) compared to the one without MIM absorber in the 7-13 µm wavelength range. The detector yields a maximum D* of 2.46 × 109 cm Hz1/2/W at 9.5 µm optimally under a working current of 30 μA. This performance-enhanced microbolometer provides a pathway for achieving ultra-sensitive imaging using a simple, cost-effective manufacturing process.

TiO2-BN/CNTs coating with radiative cooling and reduced friction

To date, the demand for electronic packaging materials with combined highly efficient heat dissipation and low friction attracts intensive attention. There have been hardly any reports of coatings that provide simultaneous radiative cooling, thermal conduction, and friction reduction properties. In the present work, a novel biomimetic nanocomposite coating is gown on the titanium alloy substrate. The coating consists of a TiO2 ceramic layer adorned with hemispherical protrusions and is enriched with hexagonal boron nitride (h-BN) flakes and CNTs on the surface. The optimal microstructures are determined through Finite Difference Time Domain (FDTD) simulation calculations and then prepared using plasma electrolytic oxidation (PEO). The results show that the hierarchical micro/nanostructures enable the coating to achieve an infrared emissivity of ∼ 0.9 within the 3–14 wavelength range, whilst h-BN and CNTs contribute to the thermal conduction of the TiO2-BN/CNTs ceramic coating. The advantage of the biomimetic nanocomposite coating over the bare titanium alloy is that the coating facilitates a reduction in the equilibrium temperature of a 5 W LED by around 21.5 °C. In addition, the coating exhibits outstanding friction reduction performance with a low friction coefficient (COF) of 0.15 over a sliding distance of 94.2 m, benefitted from the lubrication effect of h-BN and CNT. This work introduces a straightforward and environmentally friendly approach to fabricating bifunctional thermal regulation materials.

Investigating the Impact of Data Normalization Methods on Predicting Electricity Consumption in a Building Using different Artificial Neural Network Models.

The study investigates the impact of data normalization on the prediction of electricity consumption in buildings using four multilayer Artificial Neural Networks (ANN) algorithms: Long Short-Term Memory Networks (LSTM), Levenberg-Marquardt Back-propagation (LMBP), Recurrent Neural Networks (RNN), and General Regression Neural Network (GRNN). Four data normalization approaches, Min-Max Scaling, Mean, Z-score, and Gaussian function were assessed on experimental datasets. The LSTM algorithm, when combined with Min-Max normalization, showed the most favorable predictive capabilities, with a low Coefficient of Variation of the Root Mean Square Error (CVRMSE) of 10.3 and Normalized Mean Bias Error (NMBE) of 0.6. The remaining three normalization approaches showed satisfactory concordance with empirical data, but with slight disparities in precision. The LMBP model, when using Z-score normalization, had favorable performance in forecasting electricity consumption, but the discrepancies across the models were not significant. The Recurrent Neural Network (RNN) model, when used with Gaussian normalization, exhibited the most favorable performance, with the lowest Coefficient of Variation of Root Mean Square Error (CVRMSE) at 11.8 and Normalized Mean Biased Error (NMBE) at 0.6. The Generalized Regression Neural Network (GRNN) model, trained on unprocessed data, exhibited superior performance, with the lowest Coefficient of Variation of Root Mean Square Error (CVRMSE) at 19.2 and NMBE at 1.0. In conclusion, the study highlights the significant influence of data normalization on the predictive capabilities of various ANN models, suggesting that careful use of data normalization techniques can significantly improve the accuracy of electricity consumption forecasting in buildings.

Highly efficient thermal conductivity of polyarylene ether nitrile composites via the introduction of hybrid fillers and tailored cross-linked structure

Polymer dielectrics with high thermal conductivity (λ) and excellent insulating properties are of interest in miniaturized and integrated electronic devices. However, most polymers are unable to fulfill this need due to their inherent structure. In this work, a polymer alloy with balanced thermal conductive and dielectric properties was successfully prepared by polyarylene ether nitrile(PEN), bisphthalonitrile-microsphere@boron nitride nanosheets(Bm@BNNS), and silicon carbide whisker (SiCws) at different scales. Specifically, introduction of Bm@BNNS fillers with core-shell structure into PEN resins results in heterogeneous interfaces, which effectively reduces the agglomeration and dosage of BNNS and synergistically improves the λ and dielectric performance. Besides, it has high breakdown strength (Eb) and high energy storage density (242.26 kV/mm, 1.66J/cm3) when filled with only 4.37 vol% BNNS compared to pure PEN. Furthermore, effects of one-dimensional SiCws at different scales on formation of heat-conduction pathways and electrical insulation properties of PEN/Bm@BNNS composites were investigated. The findings display that PEN/Bm@BNNS/SiCws composites with large size SiCws (7.81 vol%) achieved a high λ of 2.376 W/m.K, which was 135.24 % and 87.09 % higher than pure PEN and PEN/Bm@BNNS composites, respectively. Thus, the thermal conductive pathways are constructed by line-plate structure (SiCws-BNNS), and insulating performance primarily on the core-shell structure (Bm@BNNS). Besides, the novel PEN/Bm@BNNS/SiCws hybrid materials are together with a low coefficient of thermal expansion of 38–89 ppm/°C and high Tg of 220 °C. Thus, it gives a promising insight to achieve highly λ polymer-based insulating film materials used for high-temperature-resistant fields.

A 4-port flexible MIMO antenna with isolation enhancement for wireless IoT applications

This paper presents a conformal, miniaturized, and geometrically simple monopole antenna designed for Vehicle–to–Everything (V2X) communications. The antenna consists of a flexible substrate, radiating patch, ground, and metallic stubs. Meandered lines are added to the U-shaped radiator to achieve the required bandwidth of the antenna. The antenna has |S11|< −10 dB magnitude from 5.06 to 7.24 GHz, attaining a peak low magnitude of–68 dB. The antenna is configured into a 4-port Multiple–Input–Multiple–Output (MIMO) setup to minimize the mutual coupling between its elements. The proposed flexible MIMO antenna offers bandwidth from 5.37 to 7.34 GHz and a peak moderate gain of 4.63 dBi with omnidirectional stable radiation patterns. To improve the mutual coupling, two hollow concentric circular structures, in combination with a pair of stub networks are integrated between the elements of the MIMO system. The transmission coefficient and surface current analysis confirm the effectiveness of the decoupling structure. The presented MIMO antenna is characterized by high isolation, a low envelope correlation coefficient (ECC), and high diversity gain, suitable for V2X MIMO communication scenarios.

Effect of binder phases on the microstructure and sliding wear properties of HVOF-sprayed WC-based coatings

This study aimed to evaluate the microstructure and wear properties of WC-10Co-4Cr, WC-12Co, and WC-17Co coatings on TC4 titanium alloy. The coatings were deposited using high velocity oxygen-fuel (HVOF) technique. To analyze the influence of binder phases, the coatings were thoroughly examined using scanning electron microscopy, X-ray diffractometer, microhardness tester, and friction and wear tester. The analysis of the results reveals that the primary phases in all three coatings consist mainly of WC, with smaller quantities of W2C and amorphous phases present. The WC-10Co-4Cr powder demonstrates a relatively even particle size distribution, high degree of sphericity, and rough porous surface, allowing for efficient heat absorption and uniform heat distribution, resulting in a dense coating. Notably, the WC-10Co-4Cr coating exhibits significantly smaller tungsten carbide grain size compared to the other coatings. Moreover, the microhardness of the WC-10Co-4Cr coating, measured at 1377.8 HV0.05, is significantly higher than that of the WC-12Co and WC-17Co coatings, which measured at 1258.8 HV0.05 and 1182.4 HV0.05, respectively. Additionally, the WC-10Co-4Cr coating demonstrates low friction coefficient and wear volume, indicating excellent wear resistance. Subsequently, a comprehensive analysis was conducted to determine the reasons for the relative enhancement in binder performance.

Development of Positive Tone-Type Photosensitive Materials Based on A Phenolic Resin with A Low Coefficient of Thermal Expansion

Development of Positive Tone-Type Photosensitive Materials Based on A Phenolic Resin with A Low Coefficient of Thermal Expansion

Genomic insights into the critically endangered King Island scrubtit.

Small, fragmented or isolated populations are at risk of population decline due to fitness costs associated with inbreeding and genetic drift. The King Island scrubtit Acanthornis magna greeniana is a critically endangered subspecies of the nominate Tasmanian scrubtit A. m. magna, with an estimated population of < 100 individuals persisting in three patches of swamp forest. The Tasmanian scrubtit is widespread in wet forests on mainland Tasmania. We sequenced the scrubtit genome using PacBio HiFi and undertook a population genomic study of the King Island and Tasmanian scrubtits using a double-digest restriction site-associated DNA (ddRAD) dataset of 5,239 SNP loci. The genome was 1.48 Gb long, comprising 1,518 contigs with an N50 of 7.715Mb. King Island scrubtits formed one of four overall genetic clusters, but separated into three distinct subpopulations when analysed independently of the Tasmanian scrubtit. Pairwise FST values were greater among the King Island scrubtit subpopulations than among most Tasmanian scrubtit subpopulations. Genetic diversity was lower and inbreeding coefficients were higher in the King Island scrubtit than all except one of the Tasmanian scrubtit subpopulations. We observed crown baldness in 8/15 King Island scrubtits, but 0/55 Tasmanian scrubtits. Six loci were significantly associated with baldness, including one within the DOCK11 gene which is linked to early feather development. Contemporary gene flow between King Island scrubtit subpopulations is unlikely, with further field monitoring required to quantify the fitness consequences of its small population size, low genetic diversity and high inbreeding. Evidence-based conservation actions can then be implemented before the taxon goes extinct.

Design and analysis of mode-matched decoupled mass MEMS gyroscope with improved thermal stability

This paper presents an efficient design approach for microelectromechanical systems (MEMS) gyroscope considering the design constraint of MEMSCAP’s Silicon-on-Insulator Multi-User MEMS Processes (SOIMUMPs). A design for a decoupled mass MEMS resonant gyroscope with tuning electrodes is presented to minimize cross-axis coupling and optimize the gyroscope’s performance. The device features a size of 1.8 ×2.772 mm2 . A decoupled mass MEMS gyroscope has been designed using a novel mechanical beam configuration that optimizes the structural design to reduce unwanted interactions between drive and sense axes motions. Mode order has been achieved by obtaining the first two modes as drive and sense modes at 9946.3 Hz and 10 202.7 Hz, respectively. Parallel plate electrostatic tuning electrodes have been added to adjust and match the drive and sense modes at the resonant frequencies of 9946 Hz. This mode matching is crucial for optimizing gyroscope performance, accuracy, and sensitivity. The effects of temperature variation on the performance of the designed decoupled mass MEMS gyroscope have been investigated, particularly in terms of its mode-matched operation achieved using tuning electrodes. Finite element method (FEM) simulations were conducted, demonstrating that thermal stability was achieved, and mode-matched operation was maintained within the temperature range of −40 °C to 80 °C. The gyroscope exhibits enhanced performance compared to existing MEMS gyroscopes under mode-matched conditions, featuring a lower temperature coefficient of frequency (TCF) at 0.0415 Hz °C−1 in the drive mode and 0.0165 Hz °C−1 in the sense mode. FEM analysis for the fabrication process tolerances has been done, where MEMS gyroscope’s resonant frequencies, output capacitance, output displacement, and sense mode quality factor have shown negligible changes to fabrication process tolerances. Transient analysis was conducted using CoventorWare MEMS+ 3D schematic, which was integrated with MATLAB Simulink to measure the MEMS gyroscope’s output response, which corresponded with the varying input angular velocity signal.

Influence of different processing techniques for prosthetic acrylic resins in the surface roughness parameters: a research article

BackgroundDifferent processing techniques are employed to obtain poly (methyl methacrylate) (PMMA) with consistent surface quality in terms of topography and tribological function. The purpose of this research is to evaluate its influence on the surface height distribution.MethodsIn this research, samples of conventional and CAD/CAM acrylic resins were prepared. The following surface roughness parameters were extracted from the profilometric readings: arithmetic mean roughness (Pa), skewness (Psk) and kurtosis (Pku). Profilometric profiles were additionally obtained.ResultsThe average roughness (Pa) with the conventional technique was significantly higher compared to CAD/CAM (t = 4.595; P < 0.001). Heat-cured resins presented the highest mean Pa (F = 6.975; P = 0.06). Heat-cured and milled resins show lower coefficient variation (CV) values, indicating more consistent surface finishing. The surface profiles revealed distinct characteristics in terms of skewness and kurtosis.ConclusionsThe surface processing method, chemical composition and resin type significantly influence the surface finishing of the resin. The CAD/CAM resins exhibited superior results in terms of surface arithmetic mean roughness (Pa). However, heat-cured resin revealed to present the better surface consistency.

Mechanical, wear and thermal properties of natural fiber-reinforced epoxy composite: cotton, sisal, coir and wool fibers

AbstractNatural fiber-reinforced epoxy composites (NFRCs) have gained significant attention in recent years due to their potential as environmentally friendly and sustainable materials. These composites combine natural fibers, derived from plants, with epoxy resins to create a material with enhanced properties. The objective of this study is to investigate the mechanical, wear and thermal properties of NFRCs incorporating cotton, sisal, coir and wool fibers. The vacuum-assisted resin transfer molding (VARTM) technique was employed to produce composite plates, followed by conducting tests on tensile, wear and thermal properties. The cotton composite showcased the highest tensile strength, reaching 52.81 MPa, while the coir composite exhibited the lowest, measuring 15.34 MPa. Sisal composite exhibited a moderate wear rate (1.423 mm3/Nm) and a lower coefficient of friction (0.233), implying smoother relative motion. Coir composite presented the highest wear rate (4.615 mm3/Nm), attributed to its coarse fiber nature. Thermal conductivity is highest at cotton composite (1.017 W/mK) and is lowest at coir composite (0.187 W/mK). Additionally, the highest specific heat was observed in the coir composite (26.313 MJ/m3K). Cotton demonstrated potential for efficient heat transfer, while wool outperformed in insulation. Sisal displayed versatility for structural applications. Coir emerged as an effective insulator with energy-saving applications.

The small-world effect for interferometer networks

Complex network theory has focused on properties of networks with real-valued edge weights. However, in signal transfer networks, such as those representing the transfer of light across an interferometer, complex-valued edge weights are needed to represent the manipulation of the signal in both magnitude and phase. These complex-valued edge weights introduce interference into the signal transfer, but it is unknown how such interference affects network properties such as small-worldness. To address this gap, we have introduced a small-world interferometer network model with complex-valued edge weights and generalized existing network measures to define the interferometric clustering coefficient, the apparent path length, and the interferometric small-world coefficient. Using high-performance computing resources, we generated a large set of small-world interferometers over a wide range of parameters in system size, nearest-neighbor count, and edge-weight phase and computed their interferometric network measures. We found that the interferometric small-world coefficient depends significantly on the amount of phase on complex-valued edge weights: for small edge-weight phases, constructive interference led to a higher interferometric small-world coefficient; while larger edge-weight phases induced destructive interference which led to a lower interferometric small-world coefficient. Thus, for the small-world interferometer model, interferometric measures are necessary to capture the effect of interference on signal transfer. This model is an example of the type of problem that necessitates interferometric measures, and applies to any wave-based network including quantum networks.