Angle Values Research Articles

Potential use of extracted flax seed mucilage in the construction of macroporous cryo-scaffolds

Mucilage is a natural source of polysaccharides that has recently attracted attention for use in biomaterial production. It attracts attention with its easy and fast extraction, biocompatibility, high water retention capacity, and biodegradability. Although there are studies on the characterization of mucilage obtained from different plant sources, the interaction of this polymer with other polymers and its potential to form new biomaterials have not yet been sufficiently investigated. Based on this, in this study, the potential of mucilage extracted from flaxseed for the production of cryogels for tissue engineering applications was demonstrated. Firstly, yield, basic physicochemical properties, morphology, and surface charge-dependent isoelectric point determination studies were carried out for the characterization of the extracted mucilage. The successful preparation of mucilage was evaluated for the construction of cryo-scaffolds and 3D, spongy, and porous structures were obtained in the presence of chitosan and polyvinyl alcohol polymers. A heterogeneous morphology with interconnected macro and micro porosity in the range of approximately 85–115 m pore diameter was exhibited. Due to the high hydrophilic structure of the mucilage, which is attached to the structure with weak hydrogen bonds, the contact angle values of the scaffolds were obtained below 80° and they showed the ability to absorb 1000 times their dry weight in approximately 30 min. As a preliminary optimization study for the evaluation of mucilage in cryogel formation, this work introduced a new construct to be developed as wound dressing scaffold for deep and chronic wounds.

Influence of gamma radiation on self-assembled molecular layers developed on different metals

In this work, self-assembled molecular layers (SAMs), developed from special amphiphilic molecules (undecenyl phosphonic acid) on the top of two types of stainless steels (1.4571 and 1.4841) were in focus. The metal surface was modified by a self-assembled molecular layer with a double bond at the end of the carbon chain. The modification of the structure of the unsaturated hydrophobic chain was done by gamma irradiation to produce a more compact layer. We were interested in the influence of the metal composition on the layer formation. To give answers to these questions SAM layers were deposited on the top of the stainless steels and then the nanolayers were modified by post-treatment (gamma irradiation). The thickness of the surface films was characterized by ellipsometry and the composition of the amphiphilic SAM layers by infrared spectroscopy. Atomic Force Microscope (AFM) visualized the morphological changes due to the layer deposition and the post-treatment; the surfaces were numerically characterized by roughness parameters; contact angle values proved the change in the wettability caused by the metal surface and the gamma irradiation.

DETERMINATION OF THE OPTIMAL INCLINATION ANGLE OF THE TRUSS FILLER IN A DOUBLE-WALLED TANK

The paper considers the application of the tank wall design, which is a three-layer panel consisting of two shells, between which there is a truss filler. Such a filler is a repeating spatial structure consisting of pyramids or tetrahedrons.The analysis of references concerning such a construction is carried out. As a result of the analysis, it was revealed that the three-layer panel with a truss filler found its application in aviation and rocket engineering, and all studies were carried out for structures with thickness not exceeding 150 mm, and the applied load was evenly distributed over all surfaces.To research the stress-strain state of the tank structure, two numerical models were created in the SCAD Office software package. All active loads are collected. The calculation was carried out for tank structures, in the inter-wall space of which pyramids and tetrahedrons were located.The technology used relates to cross-cutting digital, namely digital design and modeling, which is currently included in the concept of technological development of our country.The search for the optimal inclination angle of the rods was carried out in the range from 40° to 60°. Five calculations were performed for each placeholder in the corresponding ranges.As a result of geometric parameters dependencies researches of the double-walled tank wall, the inclination optimal angles values of the pyramidal and tetradrael rods fillers for the wall of a tank of 50000 m3volume were obtained. There are obtained dependences to determine the optimal inclination angle of the rods of the truss filler for a tank of any volume, using relative values, as well as the values of forces arising in the rods of the filler depending on the hydrostatic column of the liquid.

Fault probability identification method for distribution networks based on mov-MF distribution

To address the fault identification challenge in distribution networks, a method leveraging a mixture of the von Mises–Fisher (mov-MF) distribution model for fault probability identification is proposed. Initially, the synchronous phasor measuring unit is employed to gather the post-fault steady-state voltage phase quantities, and then, the voltage phase angle values are combined to form a three-dimensional feature quantity. Subsequently, the mov-MF distribution model is initialized through the spherical K-means algorithm and the minimum message length algorithm. This model is further refined via the expectation–maximization algorithm to iteratively optimize distribution parameters. The test set data are input into the mov-MF distribution model, which has been constructed using typical fault data, to discern fault types. Finally, the efficacy of the proposed method is validated through simulation verification conducted on the IEEE 33-node distribution system. The analysis of the examples demonstrates the accuracy of the mov-MF distribution model-based fault identification method in identifying single-phase ground, two-phase ground, two-phase interphase, and three-phase short-circuit faults.

Effect of Forearm Supination and Pronation on Median & Ulnar Nerve Conduction Velocity Among Throwers, Archers, and Non-Athletes

ABSTRACT The distinct and specialized movements performed in different sports disciplines may significantly influence nerve performance, potentially affecting nerve responses and the overall function within the respective athletic activities. The purpose of this study is to find the effect of forearm supination and pronation across the elbow joint on ulnar and median nerve conduction velocity (NCV) in throwers, archers, and non-athletes. A total of 34 participants both male and females were recruited with a body mass index (BMI) between 18.5 and 24.9 kg/m2. Nerve conduction study (NeuroStim NS2 EMG/NCV/EP System) was used for measuring ulnar and median NCV across the elbow joint at different angles with the forearm in supination and pronation. Repeated measure analysis of variance (RMANOVA) revealed that there are statistically significant differences in mean values of forearm positions, angles, nerves and groups (p < .05). This study illuminates distinctive NCV variations across diverse athletic groups during forearm supination and pronation movements. Pronation consistently exhibited faster ulnar NCV compared to the median nerve across throwers, archers, and non-athletes, while in supination specific joint positions revealed notable differences within sports groups and nerve function.

Research on continuous commutation failure suppression strategy for multi-feed DC transmission system considering harmonic characteristic factors

Abstract Regarding the sustained issues of commutation failures in the hybrid double-fed DC system encompassing Line Commutated Converter High Voltage Direct Current (LCC-HVDC) and Modular Multilevel Converter High Voltage Direct Current (MMC-HVDC, from the perspective of harmonics, the harmonics in the voltage waveform of the AC bus on the inverter side are analyzed. Besides, a commutation failure suppression strategy for the hybrid doubly-fed DC transmission system based on the minimum shutdown area is designed, in which the setting value of the shutdown angle of the harmonic is considered in the minimum shutdown area. The reactive power is obtained by attaching the setting value to the reactive power control link of MMC-HVDC, and the simulation analysis in PSCAD verifies that the strategy can make the MMC-HVDC output more reactive power during the fault in the weak AC system. Increasing the shut-off margin of the manifold reduces the potential for continuous commutation failures in LCC-HVDC.

The 2018 Outburst of MAXI J1820+070 as Seen by Insight-HXMT

We present an analysis of the whole 2018 outburst of the black hole X-ray binary MAXI J1820+070 with Insight-HXMT data. We focus our study on the temporal evolution of the parameters of the source. We employ two different models to fit the disk’s thermal spectrum: the Newtonian model diskbb and the relativistic model nkbb. These two models provide different pictures of the source in the soft state. With diskbb, we find that the inner edge of the disk is close to the innermost stable circular orbit of a fast-rotating black hole and the corona changes geometry from the hard to the soft state. With nkbb, we find that the disk is truncated in the soft state and that the coronal geometry does not change significantly during the whole outburst. However, the model with nkbb can predict an untruncated disk around a fast-rotating black hole if we assume that the disk inclination angle is around 30° (instead of ∼60°, which is the inclination angle of the jet and is usually adopted as the disk inclination angle in the literature) and we employ a high-density reflection model. In such a case, we measure a high value of the black hole spin parameter with observations in the soft state, in agreement with the high spin value found from the analysis of the reflection features and in disagreement with the low spin value found by previous continuum-fitting method measurements with the disk inclination angle set to the value of the jet inclination angle.

Optimal design, construction and evaluation of symmetric compound parabolic concentrator integrated with photovoltaics system (CPC-PV)

To enhance the production and efficiency of photovoltaic systems, research has been conducted on various techniques including the use of compound parabolic reflectors (CPCs). A mathematical model is developed using the governing solar radiation and CPC geometry equations to optimize the geometrical parameters required for the experimental setup. The optimal values for the half acceptance angle and tilt angle were found to be 25° and 35°, respectively. Based on these optimal parameters, a laboratory setup was fabricated and evaluated. To compare the performance of our CPC-based system, three different panels constructed: a simple PV panel without a concentrator, a PV panel with a concentrator but without cooling (CPC-PV), and a PV panel with a concentrator and water cooling (CPC-PVT). Results showed that the use of a CPC with a concentration ratio of 1.7 in both modes, with and without cooling, led to a 10 % and 20 % increase in the output power, respectively, compared to the simple PV panel. In summary, this study demonstrates the effectiveness of using a CPC in enhancing the production and efficiency of photovoltaic systems. The mathematical model developed in this research can be utilized for optimizing the geometrical parameters required for the design of CPC-based systems. The experimental results obtained from this study indicate that the use of a CPC with water cooling can significantly improve the energy output of the photovoltaic system. These findings can aid in the design of cost-effective and efficient photovoltaic systems.

Poster 203: Staged Hip Arthroscopy and Periacetabular Osteotomy Versus Hip Arthroscopy Alone in Patients with Borderline Hip Dysplasia: A Propensity-Matched Study

Objectives: The management of borderline hip dysplasia (BHD) remains an area of interest in the field of hip preservation. The purpose of this study was to (1) evaluate mean 2-year outcomes for patients with BHD treated with staged hip arthroscopy and periacetabular osteotomy (PAO) to those who underwent hip arthroscopy alone, and (2) evaluate rates of complications, hardware removal, reoperations, conversions to total hip arthroplasty (THA), along with conversions to PAO. Methods: Hips with a lateral center-edge angle (LCEA) values 18° ≤ LCEA &lt; 25° that underwent a hip arthroscopy for femoroacetabular impingement syndrome (FAIS) between January 2018 and June 2022 were reviewed. Patients who underwent staged periacetabular osteotomy and hip arthroscopy were identified. Staged hips were propensity-matched 1:4 to other borderline dysplastic hips that underwent hip arthroscopy alone. Matching was performed based on age, sex, and body-mass index (BMI). Patient-reported outcomes (PROs) were collected, including Hip Outcome Score – Activities of Daily Living (HOS-ADL), HOS-Sports Specific (HOS-SS) subscale, 12-item International Hip Outcome Tool (iHOT-12) questionnaire, Patient-Reported Outcomes Measurement Information System-Pain Interference (PROMIS-PI) subscale, and PROMIS-Physical Function (PROMIS-PF) subscale. Cohort-specific minimal clinically important difference (MCID) and Patient Acceptable Symptom State (PASS) thresholds were calculated. Postoperative PROs, rates of MCID/PASS achievement, and rates of reoperation and conversion to THA were compared. Results: Twenty-four patients who underwent staged hip arthroscopy and PAO were successfully matched to 96 patients who underwent hip arthroscopy alone. Both groups were similar in terms of age, sex, and BMI. The patients who underwent a PAO had smaller LCEAs and larger Tönnis angles (21.0° vs. 23° and 11.6° vs. 9.1°, respectively). Both groups demonstrated significant improvement in PROs at minimum 1-year postoperatively (p &lt; 0.001, for all). There were no significant differences in postoperative PRO scores between the groups (p ≥ 0.223, for all). There were no significant differences in MCID/PASS achievement (p ≥ 0.224. for all). There were no reoperations or conversion to THA in the staged hip arthroscopy and PAO group. In the hip arthroscopy alone cohort, reoperation rates were 5.2% and conversion to THA occurred in 1% of the patients. There were no significant differences in secondary surgery rates between the groups (p = 1.000). Three patients in the hip arthroscopy alone group ultimately underwent PAO, 1 underwent a proximal femoral osteotomy (PFO), and one underwent a revision hip arthroscopy. These female patients were young and athletic with an LCEA &lt; 20°. Conclusions: Patients undergoing staged PAO and hip arthroplasty and isolated hip arthroplasty for treatment of BHD demonstrate similar clinical improvement. Rates of revision surgery and conversion to THA were similarly low. A small subset of patients who were initially treated arthroscopically ultimately received a PAO. This group was entirely made up of young, athletic female patients. This is encouraging early data and more long-term data is needed to evaluate the differences in survivorship. [Figure: see text]

Distal radius fractures after 75 years of age: are six-month functional and radiological outcomes better with plate fixation than with conservative treatment?

BackgroundSurgery and non-operative treatment produce similar 1-year functional outcomes in patients older than 65 years. Data are lacking for patients older than 75 years. The main objective of this study was to compare surgical vs. non-operative treatment regarding short-term outcomes in patients older than 75 years. In addition to an overall analysis, sub-group analyses were done in patients with displacement and severe displacement (>20 ° posterior tilt). HypothesisSurgery provides better clinical and radiological outcomes than does non-operative treatment. Patients and methodsPatients older than 75 years at the time of a distal radius fracture were included prospectively over a 2-year period. A follow-up duration of at least 6 months was required. Treatment choices were based on displacement, Charlson’s Co-morbidity Index, and patient autonomy. Surgery consisted in open fixation using an anterior locking plate and non-operative treatment in a short arm cast without reduction. The main assessment was based on clinical criteria: range of motion, strength, visual analogue scale (VAS) scores, the short version of the Disabilities of the Arm, Shoulder, and Hand tool (QuickDASH), the Patient Rated Wrist Evaluation (PRWE), and the 36-Item Short Form Health Survey (SF-36). The secondary assessment criteria were the radiological outcomes and the complications. Results74 patients were included, among whom 24 were treated surgically and 50 non-operatively. At 1.5 months, surgery was associated with significantly better results for flexion, ulnar inclination, and supination, with range increases of at least 7 ° vs. non-operative treatment, and with greater dorsal angle and ulnar variance values (p < 0.05 for all comparisons). At 6 months, pronation and the radio-ulnar index were better with surgery (p < 0.05 for both comparisons). In the patients with displacement or severe displacement, surgery was associated with 10° gains vs. conservative treatment for flexion, ulnar inclination, and supination at 1.5 months (p < 0.05 for all comparisons). DiscussionIn patients older than 75 years, surgery for distal radius fracture was associated with significantly better clinical and radiological outcomes within 6 months. Surgery is recommended for displaced and severely displaced distal radius fractures to expedite the recovery of joint motion ranges. Beyond 6 months, the outcomes are similar. Level of evidenceIII.

The Differences on the Fatty Infiltration of Paraspinal Muscles between Single- and Multiple-level Intervertebral Disc Degeneration in Patients with Lumbar Disc Herniation.

Multiple-level Intervertebral disc degeneration (IDD) in patients with lumbar disc herniation (LDH) is related to postoperative re-herniation and low back pain. Although many investigators believed that there is an interdependence between paraspinal muscles degeneration and IDD, few studies focused on the fatty infiltration of paraspinal muscles on single- and multiple-level IDD in patients with LDH. This study aims to investigate the difference on the fatty infiltration of paraspinal muscles between single- and multiple-levels IDD in patients with LDH. and to explore in patients with LDH whether fatty infiltration is a potential risk factor for multiple-level IDD. This study was conducted as a retrospective observational analysis of 82 patients with LDH from January 1, 2020 to December 30, 2020 in our hospital were enrolled. Twenty-seven cases had single-level IDD (Group A), and 55 cases had multiple-level IDD (Group B). We measured the mean computed tomography (CT) density value of the paraspinal muscles, including multifidus (MF), erector spinae (ES) and psoas muscle (PM) at each disc from L1 to S1. Subgroups were set to further analyze the odds ratio (OR) of fatty infiltration of paraspinal muscles in different sex and BMI groups. We measured sagittal angles and analyzed the relationships between these angles and IDD. Finally, we use logistic regression, adjusted for other confounding factors, to investigate whether fatty infiltration is an independent risk factor for multi-level IDD. The average age in multi-level IDD (51.40 ± 15.47 years)was significantly higher than single-level IDD (33.37 ± 7.10 years). The mean CT density value of MF, ES and PM in single-level IDD was significantly higher than multi-level IDD (all ps < 0.001). There was no significant difference of the mean value of angles between the two groups. No matter being fat (body mass index [BMI] > 24.0 kg/m2) or normal, patients with low mean muscle CT density value of MF and ES are significantly easier to suffer from multiple-level IDD. In the pure model, the average CT density value of the MF, ES and PM is all significantly associated with the occurrence of multi-IDD. However, after adjusting for various confounding factors, only the OR of the average CT density value for MF and ES remains statistically significant (OR = 0.810, 0.834, respectively). In patients with LDH, patients with multiple-level IDD have more severe fatty infiltration of MF and ES than those with single-level IDD. Fatty infiltration of MF and ES are independent risk factors for multiple-level IDD in LDH patients.

Study on Grain Boundary Mechanical Behaviors of Polycrystalline γ-TiAl Using Molecular Dynamics Simulations

In this study, the molecular dynamics (MD) method was used to study the tensile deformation of polycrystalline γ-TiAl with complex and random grain orientations. Firstly, the tensile deformation was simulated with different average grain sizes (8.60 nm, 6.18 nm, and 4.50 nm) and strain rates (1 × 108 s−1, 5 × 108 s−1, and 1 × 109 s−1). The results show that the peak stress increases with an increase in tensile strain rate, and the peak stress decreases as the grain size decreases, showing an inverse Hall–Petch effect. Upon observing atomic configuration evolution during tensile deformation, it is found that the grain boundary is seriously distorted, which indicates obvious grain boundary sliding occurring. With a further increase in the loading, some dislocations nucleate at the grain boundaries and propagate towards the interior of the grains along the grain boundaries, which demonstrates that dislocation motion is the primary coordination of the mechanical process of the grain boundaries. The dislocation density near the grain boundaries continues to increase, leading to the generation of micro-cracks and eventually causing material failure. Another interesting phenomenon is that the grains rotate, and the specific rotation angle values of each grain are quantitatively calculated. Grain rotation relaxes the stress concentration near the grain boundaries and plays a toughening role. Consequently, the plastic deformation behaviors of polycrystalline γ-TiAl are achieved through the grain boundary mechanical process, that is, grain boundary sliding and grain rotation.

Angle-tuned optical interleaver based on Fabry–Perot cavities with reconfigurable angle range

This paper presents a thin film coupled Fabry–Perot cavities optical interleaver. The simulation results for the interleaver shows an outstanding performance in accurately selecting the required channels and robustness in the channel profile. The accuracy is achieved by varying the range of the incident angle. Furthermore, the interleaver has a re-configurable incident angle range with fine and coarse angle ranges, which provides a broader range of applications for such an interleaver. Moreover, the proposed approach provides the reconfigurability for the interleaver performance, which is now a reconfigurable thin-film-based device for selecting the odd/even interleaved channels. The channel selection is based on specific angle values for fine and coarse ranges. Such a device will add more flexibility and multi-functionality to the optical system.

Slow‐release fertilizer behavior of polyvinyl alcohol (PVA)/urea/TiO2 nanofiber membrane

AbstractNanofiber is a material used as a drug carrier matrix in drug release materials. Its morphology has high porosity and good flexibility, making it suitable for this purpose. The use of nanofiber as a carrier matrix in slow‐release fertilizer (SRF) material is expected to provide a solution for releasing fertilizer into the soil more measurably and efficiently In this study, PVA/Urea/TiO2 nanofibers were fabricated using the electrospinning method. PVA/Urea/TiO2 SRFs were prepared using varying urea mass percentages (10%, 15%, and 20% of PVA mass) and the concentration of titanium dioxide suspension solution (0, 0.2, and 0.4 mL). Every sample was analyzed using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) and tested using contact angle and slow‐release tests. From SEM characterizations, all samples showed the ability to form nanofiber. It was found that the membrane diameter sizes for each sample A, B, C, D, E, and F were 341 ± 5, 309 ± 12, 109 ± 3, 313 ± 10, 109 ± 3, and 158 ± 6 nm, respectively. The FTIR characterizations showed that all the matrix samples successfully contained the nitrogen group, which was found at wave number 1605 cm−1 (NH deformation), 1574 cm−1 (CN stretching), and 3430 cm−1 (NH stretching). The SEM mapping images confirmed the presence of titanium dioxide (green dots). The contact angle test showed that all samples had hydrophilic properties (the contact angle value lower than 90°), and the greatest value of contact angle measurement was 31.08° for sample C/E (sample with the most presence of TiO2 suspension solution 0.4 mL). The sample with the greatest TiO2 suspension concentration (0.4 mL) had the longest urea release time, lasting 8 days. This result indicates the addition of TiO2, can potentially suppress the hydrophilic properties of the PVA membrane. It is found that the addition of TiO2 influenced the membrane's hydrophilicity, consequently increasing the release rate. This study used the Korsmeyer–Peppas mathematical kinetic model to show that diffusion and swelling are release mechanisms for SRF membranes.

Synthesis and Characterization of New Chiral Smectic Four-Ring Esters.

Orthoconic antiferroelectric liquid crystals (OAFLCs) represent unique self-organized materials with significant potential for applications in photonic devices due to their sub-microsecond switching times and high optical contrast in electro-optical effects. However, almost all known OALFCs suffer from low chemical stability and short helical pitch values. This paper presents the synthesis and study results of two chiral AFLCs, featuring a four-ring structure in the rigid core and high chemical stability. The mesomorphic properties of these compounds were investigated using polarizing optical microscopy and differential scanning calorimetry. Spectrometry and electro-optical studies were employed to estimate the helical pitch, tilt angle, and spontaneous polarization of the synthesized compounds and the prepared mixtures. All studied compounds exhibit enantiotropic chiral smectic mesophases including the SmA*, the SmC*, and a very broad temperature range of the SmCA* phase. Doping top-modern antiferroelectric mixture with synthesized compounds offers benefits such as increased helical pitch and tilt angle values without significantly influencing spontaneous polarization. This allows the prepared mixture to be regarded as an OAFLC with high optical contrast, characterized by an almost perfect dark state. These valuable physicochemical and optical properties suggest significant potential of studied materials for practical applications.

A comparative assessment of condylar inclination in completely edentulous patients using cone beam computed tomography and Arcus digma II

Statement of problemCondylar inclination affects denture fabrication and placement, especially when bilateral balanced occlusion is provided. However, comparisons between radiographic techniques and clinical procedures are lacking. PurposeThe purpose of this clinical study was to investigate the effects of cone beam computed tomography (CBCT) and Arcus digma II on horizontal condylar inclination and bilateral balanced occlusion. Material and methodsTwelve completely edentulous individuals were provided with complete dentures with teeth in bilateral balanced occlusion. The horizontal condylar angle was measured using CBCT and the Arcus digma II with a 6-mm mandibular protrusion. The CBCT had a real-time 3D image, and the Arcus digma II method recorded mandibular movement using electronic sensors. To evaluate the clinical performance, the horizontal condylar angle was measured using the 2 methods and applied to the semi-adjustable articulator to evaluate the balanced occlusion. The Shapiro-Wilk test was used to assess normality, and a paired t test was used to assess the normally distributed data (α=.05). ResultsThe horizontal condylar guidance angle values for both sides of Arcus digma II were significantly higher than from CBCT (P<.05). No difference was found in the clinical performance of balanced occlusion of complete dentures in the 2 methods. ConclusionsThe Arcus digma II method yielded higher horizontal condylar angle measurements than from CBCT. However, no significant difference was found between Arcus digma II and CBCT in terms of the effect on balanced occlusion. Arcus digma II appears to be a reliable technique for measuring the horizontal condylar angle, similar to CBCT, and can be used as an alternative method.

Viscous Elastic Asphalt Characteristics of Cariphalte Modification with Addition of Gilsonite Viewed from Phase Angle Value

Performance Grade (PG) Bitumen is bitumen that is graded based on its performance at different temperatures. In the Superpave grading system, asphalt binders are classified according to their performance in extreme hot and cold temperatures and are referred to as performance grade (PG) asphalt. The main objective of assessing and selecting asphalt binder using the PG system is to ensure that the binder has properties suitable for the environmental conditions in the field. Cariphalte is a premium grade polymer modified bitumen used in road and airport construction and other similar applications. Cariphalte is a Styrene Butadine Styrene (SBS) modified bitumen. The SBS in Cariphalte ensures the formation of a 3-dimensional network in the bitumen thereby reducing the temperature susceptibility and increasing the stiffness modulus at high temperatures. Cariphalte is also resistant to oxidation, reducing deformation and slowing secondary solidification. To get an idea of the improvement in rheological properties due to the addition of gilsonite, tests were carried out on a mixture of cariphalte and gilsonite asphalt with 6 variations of gilsonite content. The tests carried out include basic rheological properties testing and mechanistic rheological properties testing. From this research, the test results showed that at the same temperature, asphalt with the addition of 0% gilsonite had the smallest phase angle (δ) compared to asphalt using the addition of gilsonite. This explains that the addition of gilsonite can increase the phase angle (δ) value of PG-76 asphalt, which makes the asphalt material have thicker characteristics.

TESTING OF BLEACHING ON COCOBOLO (Dalbergia retusa Hemsl.,) WOOD

In this study, the effects of single and double component wood bleaching chemicals on the color parameters, glossines values and whiteness index values of cocobolo (Dalbergia retusa Hemsl.,) wood were investigated. Single and double component bleaching chemicals were applied to the wood material surfaces with the application technique in line with the company’s recommendations. Test measurements were made on bleached and unbleached wood materials. Obtained results were compared with each other. According to the determined results, lightness (L*) value, chroma (C*) value, red (a*) color tone, yellow (b*) color tone, hue (ho) angle value, glossiness values perpendicular to fibers (⊥) and parallel (║) directions at 60o, glossiness value at 85o in parallel (║) direction to the fibers, and whiteness index (WI*) values in perpendicular (⊥) and parallel (║) directions to the fibers were determined. The ∆E* values were found to be 10.22 in the double component and 2.31 in the single component. While the two-component bleaching chemical caused an increase in L*, b*, a*, C* and ho values, it caused a decrease in the one-component bleach chemical. All WI* values were increased with two component bleaching chemicals. The glossiness values at 60° in the perpendicular and parallel directions to the fibers were decreased with one component bleaching chemical. The bleaching chemicals used in the study caused different results on wood material surfaces.

Assessing the Effect of Twisting and Twisting Fatigue on ZnO:Al Thin Film Performance on PEN and PET Substrates.

This study examines the electromechanical characteristics of aluminium-doped zinc oxide (AZO) films. The films were produced using the RF magnetron sputtering process with a consistent thickness of 150 nm on various polymer substrates. The study focuses on assessing the electro-mechanical failure processes of coated segments using flexible substrates, namely polyethylene naphthalate (PEN) and polyethylene terephthalate (PET), with a specific emphasis on typical cracking and delamination occurrences. This examination involves conducting twisting deformation together with using standardised electrical resistance measurements and optical microscope monitoring instruments. It was found that the crack initiation angle is mostly dependent on the mechanical mismatch between the coating and substrate. Higher critical twisting angle values are observed for the AZO/PEN film during twisting testing. Relative to the perpendicular plane of the untwisted sample, it was found that cracks initiated at a twist angle equal to 42° ± 2.1° and 38° ± 1.7° for AZO/PEN and AZO/PET, respectively, and propagated along the sample length. SEM images indicate that the twisting motion results in deformation in the thin film material, leading to the presence of both types of stress in the film structure. These discoveries emphasise the significance of studying the mechanical properties of thin films under different stress conditions, as it can impact their performance and reliability in real-world applications. The electromechanical stability of AZO was found to be similar on both substrates during fatigue testing. Studying the electromechanical properties of various material combinations is important for selecting polymer substrates and predicting the durability of flexible electronic devices made from polyester.

Determining the influence of seasonal tilt angle on the efficiency of fixed solar photovoltaic modules

The object of this study is photovoltaic modules with different seasonal tilt angles at different geographical latitudes. The average annual efficiency of photovoltaic modules with different seasonal angles set at different geographical latitudes has been determined as the annual weighted average value of the cosine of the angle of incidence of solar rays on the plane of the photovoltaic module. The influence of seasonal tilt angles of photovoltaic modules at different geographical latitudes on their average annual efficiency was analyzed. Approximate values of the seasonal tilt angles of photovoltaic modules at different geographic latitudes take values that differ from the geographic latitude value by plus 15° for the winter period and minus 15° for the summer period. Modeling the average annual efficiency of photovoltaic modules depending on the seasonal tilt angles at different geographical latitudes made it possible to obtain refined values of the seasonal tilt angles of photovoltaic modules. Thus, at the latitude of 0°, 10°, 20°, 30°, 40°, 50°, and 60°, the tilt angle of photovoltaic modules for the winter period will be 14.8°, 24.6°, 34.5°. 44.4°, 54.1°, 63.6°, and 73°, respectively, and for summer ‒ minus 14.5°, minus 4.6°, 5°, 15.1°, 25.1°, 34.9°, and 44.7°. Dependences were obtained for determining the seasonal tilt angles of photovoltaic modules depending on the value of geographic latitude. The difference in the average annual efficiency of photovoltaic modules, which are installed at seasonal angles, and photovoltaic modules, which track the position of the Sun in the vertical plane, is 0.4 %. The results could be used as a basis for evaluating the efficiency of photovoltaic modules when determining the seasonal tilt angle at different geographic latitudes