Hole Diameter Research Articles

Jet array impingement heat transfer in a rectangular cavity with effusion holes

Various researchers have studied jet array impingement heat transfer in impingement/effusion cooling systems. However, there is a lack of research on impingement/effusion cooling systems installed within rectangular cavities that focus on the impact of the proximity of the jet hole to the cavity sidewalls on cooling performance. The main objective of this study is to investigate the flow and heat transfer characteristics of jet array impingement with effusion holes in a rectangular cavity, considering various spacings between the cavity sidewalls and the outermost jet hole. The design parameters in this study include the ratio of the jet hole pitch to jet hole diameter of 7.1, 10.0, and 16.7, and the ratio of the distance between the jet and impingement plates to jet hole diameter of 2, 6, and 10, with the Reynolds number based on the jet hole diameter ranging from 2500 to 15,000. Heat transfer characteristics in the stagnation region and wall jet region were examined using local Nusselt number distributions on the impingement surface, measured by liquid crystal thermography. The local Nusselt number was high in the stagnation region and decreased radially from the stagnation region as the wall jet region formed. The closer the outermost jet hole is to the sidewall, the higher the Nusselt number on the impingement surface near the sidewall. Moreover, the flow structure in the rectangular cavity was numerically investigated, and the velocity vectors and streamlines showed that primary and secondary vortices were generated in the middle of two neighboring jets and near the sidewall, respectively. This study also assessed previous average Nusselt number correlations. Based on experimentally determined average Nusselt number data with 54 center unit cells and 1296 side unit cells, new correlations to predict the average Nusselt number on the impingement surface in a rectangular cavity with effusion holes were developed.

Effect of geometric parameters on dynamic fracture toughness of compact tensile specimens

In this paper, the dynamic fracture toughness test and numerical simulation of CT specimens of 2A12-T4 aluminum alloy were carried out by using strain gauge method and finite element method based on Hopkinson tensile bar experiment device. The influence of crack transverse shape, loading hole size and dimension on the dynamic fracture performance of CT specimens was explained. The experimental and simulation results show that for CT specimens with different internal cracks, the time to reach stress equilibrium at the same tensile stress wave loading is roughly the same, while the time of initial cracking varies slightly. The dynamic fracture toughness obtained by concave arc-shaped internal crack and straight line-shaped internal crack is basically the same, while other changes in crack shape have a large impact. For CT specimens with straight line-shaped cracks, the position of the loading hole has a small effect on the dynamic fracture of the CT specimen under the same tensile stress wave. However, when the position of the loading hole is fixed, changing the diameter of the loading hole has a significant effect on the dynamic fracture toughness of the CT specimen.

PROFILING THE SURFACE OF THE PIN HOLE IN THE PISTON BODY

Minimization of the mass of the piston kit, which consists of three main parts - piston, pin and connecting rod, is connected, among other things, with the possibility of reducing the diameter of the steel pin. On the other hand, a decrease in its diameter inevitably leads to an increase in stresses in the piston pin hole (PPH) and possible destruction. It is known that reducing the mass of the piston set from 5 to 20% leads to an increase in the output parameters of the internal combustion engine - torque and power by 1% to 4.5%. The purpose of the study is to determine the possibility of reducing the stresses in the bearing due to the profiling of its surface while reducing the diameter of the piston pin. The research algorithm is presented, which consists of building a geometric model of the piston assembly, loading with excessive pressure taking into account the plasticity of the material, modifying the geometry of the PPH and checking the stresses of the loaded state. The conventional piston model has the following geometry: diameter – 80 mm; height – 60 mm; compression height – 30 mm; the diameter of the finger hole is 18 mm; the distance between the bumps is 28 mm. Piston material – aluminum-based alloy – AISI 2014-0, pin and connecting rod material – AISI 1020 steel. Pressure loading conditions: taking into account plasticity – nonlinear, harmonic, 2 cycles, maximum amplitude – 8 MPa; test - static, 6.5 MPa. A crumpling zone with residual deformations was detected in the PPH, the maximum final deformation practically does not differ in the first and second load cycles (0.0081 vs. 0.0084). Residual deformations occur 1/3 of the length from the inner edge of the head. The absolute residual deformations are given in the form of a sweep of the change in the PPH radius. The maximum value is about 0.04 mm. This result is the basis for modifying the geometry of the surface of the finger hole. The modified geometry of the PPH is obtained by boring the cylindrical surface with a profile modeled by the appropriate spline on the geometric model. The boring axis is offset by 0.02 mm from the PPH axis. Verification modeling showed that the averaged loads on the edge of the model are 143 MPa for the cylindrical and 107 MPa for the modified PPH (-25% for the modified profile).

Experimental and numerical study on the effect mechanism of geometric parameters on jet impingement cooling in a limited space

In order to meet the development needs of the internal cooling structure of gas turbine blades, this paper researches the jet impingement cooling in a limited space. Numerical simulation method is employed to obtain the flow field details and analyze the flow and heat transfer mechanism. The heat transfer coefficient distribution of the target surface is obtained by the transient liquid crystal, which verifies the accuracy of the CFD results. The effects of inlet mass flow rate m˙in, rows of jet holes N, jet hole diameter Dj, jet-to-target distance H/Dj and transverse distance between jet holes S/W are considered. The results show that: The flow and heat transfer characteristics at different m˙in are qualitatively similar. N has a significant effect on the heat transfer coefficient and total pressure difference. With the increase of N, the heat transfer coefficient and the total pressure difference decrease. Dj has obvious effect on heat transfer coefficient and total pressure difference. As Dj increases, both the heat transfer coefficient and the total pressure difference decrease. H/Dj has only a slight effect on the heat transfer coefficient and total pressure difference. When H/Dj increases from 1.2 to 2.2, the heat transfer coefficient increases and the total pressure difference decreases. When H/Dj increases from 2.2 to 3.2, the heat transfer coefficient decreases and the total pressure difference is almost unchanged. The effect of S/W on the heat transfer coefficient and total pressure difference is more obvious than that of H/Dj. The heat transfer coefficient and total pressure difference are the largest when S/W = 0.5. The structure with N = 8，Dj = 24 mm，H/Dj = 2.2，S/W = 0.5 has the best comprehensive heat transfer performance under the range of the boundary condition.

Supercontinuum generation in Ga‐Sb‐S chalcogenide‐based PCF using optofluidic approach

AbstractWe report the design and theoretical study of a Ga‐Sb‐S chalcogenide glass‐based photonic crystal fiber (PCF) structure for mid‐infrared supercontinuum generation. The proposed design is engineered by adjusting the diameter of air holes in the cladding region and pitch, giving us control over the dispersion characteristics of the fiber. The optimized structure design offers the Zero Dispersion Wavelength of 5.2 μm. When pumped with 50 fs secant hyperbolic pulses of peak power 4.9 kW, for a fiber of length 8 mm at pump wavelength of 5 μm, the proposed structure design produces an ultra‐broadband supercontinuum spectrum spanning 1.5–14 μm. Proposed PCF design should be helpful in, biomedical imaging, supercontinuum sources, biosesning, and optical coherence tomography.

Long-term Visual Outcomes in Patients With Idiopathic Macular Hole Surgery.

This study assesses long-term outcomes following surgical repair of idiopathic full-thickness macular holes (FTMHs) in patients with at least 5 years of postoperative follow-up. A retrospective study evaluated patients diagnosed with idiopathic FTMH who received surgical repair at a single tertiary center with at least 5 years of postoperative follow-up. Data collection included demographic and preoperative characteristics along with macular hole structural integrity as determined by spectral-domain optical coherence tomography (OCT). Functional and structural improvement were assessed by collection of visual acuity and findings on OCT at determined time points until 9 years of follow-up. The study comprised 90 eyes of 80 patients with a mean age of 67.2 ± 6.8 years, with an average postoperative follow-up of 80.8 ± 17.4 months (range 54 to 130 months). The mean macular hole diameter was 239.7 µm ± 92.2. Macular hole reoperation occurred in four eyes (4%) at a mean duration of 5.5 ± 6 months (range 0.3 to 13 months). Over the study duration, ellipsoid zone (EZ) integrity was maintained in 67.8% of eyes, with an absence of intraretinal fluid (IRF) in 96% on final OCT. The preoperative mean Early Treatment Diabetic Retinopathy Study (ETDRS) best visual acuity (BVA) of 51 improved to a mean BVA of 76 at 5 years postoperatively, with an average gain of 24 letters at one year that remained stable over 5 years (P < 0.05). Eight years after surgical repair, more than 80% of patients achieved a BVA > 65. Vitreoretinal surgery for idiopathic FTMH resulted in successful hole closure and sustained visual acuity improvement over long-term follow-up. [Ophthalmic Surg Lasers Imaging Retina 2024;55:XX-XX.].

Comparative evaluation of image quality between virtual grid and grid portable radiographic systems

Purpose. Virtual Grid (VG) is an image processing technique designed to address scattered radiation from radiographic systems without a physical grid. It aims to eliminate artifacts caused by grid misalignment and enhance radiographic workflow efficiency. We intend to evaluate image quality between Virtual Grid and grid-based radiographic systems across various patient thicknesses. Methods. A Fujifilm Virtual Grid and GE AMX-4 portable radiographic system was used. Image quality was assessed using MTF, NPS, LCR, and CNR. MTF calculations employed an edge-device method with a 0.1 mmCu sheet. For NPS evaluation, uniform images were acquired with multiple 30 × 30 cm solid water blocks (2 cm thick), overlaid in 2 cm increments to simulate patient sizes from 2cm to 40 cm. LCR and CNR were evaluated using a CIRS test plate with 9-hole depths for a hole diameter of 0.375’. The test object was placed on top of the detector then water blocks, while maintaining the same SID, beam quality, and exposure between the units. Visual assessments were conducted by four readers, quantifying perceived hole numbers. The weighted Cohen’s Kappa and Welch’s T-test were utilized for statistical analysis. Results. At 80% MTF, VG exhibited high contrast resolution of 1.1 l p/mm compared to 1.2 l p/mm for the grid system. VG demonstrated lower noise levels across all frequencies for equivalent patient thicknesses. Welch’s T-test indicated no significant differences in LCR (P = 0.31) and CNR (P = 0.34) between the systems. However, qualitative observation demonstrated VG’s better low contrast response for patient sizes ≥10 cm. The average weighted Cohen’s Kappa value was 0.78. Conclusion. This work indicates the Virtual Grid technology can effectively mitigate scattered radiation to improve granularity and low-contrast resolution in an image compared to a grid system. Furthermore, it can potentially reduce patient dose.

Sound absorption properties and mechanism of multi‐layer micro‐perforated nanofiber membrane

AbstractAiming at achieving low‐frequency and broadband sound absorption under the premise of light and thin layers, in this paper, polyvinyl butyral (PVB) nanofiber membranes were micro‐perforated and then combined sequentially to prepare multi‐layer micro‐perforated nanofiber membrane (MPNM) for acoustic noise reduction. It was demonstrated that the multi‐layer MPNM exhibited a high absorption (constantly over 50%) in the frequency of 480–2500 Hz. In addition, the established theoretical model of the sound absorbing coefficient can accurately predict the sound absorption performance of the structure with different layers, which can provide a theoretical foundation for the design of the structure of the nanofibrous membrane acoustic absorber. Based on the proposed acoustic model, the relationships between the absorption properties and the parameters were investigated, and it was found that the effective acoustic absorption frequency range and acoustic absorption coefficient curve of the multi‐layer MPNM were closely related to the size and arrangement of hole diameter, perforation rate, fiber membrane thickness, and cavity depth. Optimization of the structural parameters utilizing algorithms can achieve superior sound absorption performance, with an average absorption coefficient of 0.81 in the frequency of 100–2500 Hz. This study provides a theoretical and experimental basis for the development of low‐frequency sound‐absorbing materials and is of great significance for optimizing the acoustic performance of nanofiber membranes and expanding their applications in various acoustic engineering applications.

Application of a xenopericardial plate for closing a laparostomy in conditions of a purulent-inflammatory process

The aim of the study is to study the morphological changes in tissue in the laparostomy area when it is closed with a xenopericardial plate under conditions of an active purulent-inflammatory process. Material and methods. Analysis of data from patients at the Penza regional clinical hospital named after. N.N. Burdenko, with diseases of the abdominal organs, complicated by diffuse purulent peritonitis. During treatment, xenopericardial plates with perforations in a checkerboard pattern were used (hole diameter 0.5 cm). Disinfection of the material was carried out with a sterile solution of furacilin. Using the standard hematoxylin and eosin staining protocol, as well as alternative staining methods according to Van Gieson and Weigert, light-optical examination of stained sections was carried out at a magnification of 40–400 times. Results. In 8 out of 9 patients participating in the study, a favorable course of the inflammatory process was observed; on the 21st day after laparotomy, the symptoms of peritonitis were eliminated, the surgical wound was sutured. In one case, progression of local and general signs of peritonitis was observed within two weeks. After replacing the xenopericardial plate, the course of changes in the surgical wound was favorable. On day 21, the laparotomy wound was also sutured. Repeated examination of the biomaterial one year and two months after implantation of the xenopericardial plate into the anterior abdominal wall did not reveal signs of inflammation. Conclusions. The xenopericardium performed well in conditions of purulent inflammation and in most cases was not subject to melting. In the long term, biointegration of the xenopericardium into its own connective tissue occurred.

Effect of web holes on web crippling capacity of rectangular hollow steel sections under two flange loadings

This paper presents experimental and numerical investigations on web crippling behavior of hot rolled rectangular hollow section (RHS) with web holes. A total of 20 rectangular hollow sections, subjected to interior-two-flange (ITF) and end-two-flange (ETF) loading conditions undergoing web crippling, were experimentally tested. The experimental program was designed to obtain web crippling of specimen having slenderness (h/t) value of 21.32, by varying size and offset distance of web holes under two flange loading conditions. Finite element models of experimentally tested beams were developed, and results of finite element analysis showed good agreement with experimental results. A parametric study was then conducted using finite element analysis on different cross section sizes, to demonstrate the effect of size and position of web holes on web crippling capacity of rectangular hollow sections. It was demonstrated that ratio of diameter of web hole to the depth of flat portion of web (a/h) and ratio of offset distance of web hole to the flat portion of web (x/h) are the primary parameters affecting the web crippling strength. Design recommendations in the form of reduction factors for both loading conditions are proposed, that are conservative to both experimental and finite element results. To assess the reliability level of design recommendations, reliability analyses were undertaken.

The investigation of double wall cooling configuration with spherical cavity

Double wall cooling is an efficient cooling method for turbine blade. Commonly used double wall cooling configurations contains a cubic cavity between two walls. Chaos flow flied in the cavity impedes heat transfer. In this research, a new spherical cavity was proposed, traditional cubic cavity was replaced by several spherical cavities, film hole located on the top of spherical cavity, and impact hole located at the button of spherical cavity. Adjacent spherical cavities were connected by channel. Different spherical cavities were established and numerical simulation was used to check their performance. The influence of blowing ratio, channel, film hole diameter, spherical cavity diameter was analyzed. The performance of cavities was also compared with common double wall cooling configurations. According to the result, when blowing ratio was 0.3, spherical cavity increased cooling effectiveness by 45.6% maximumly compared to common configurations. As for coolant consumption, spherical cavity needs less coolant than common configurations to achieve the same cooling effectiveness. What's more, film hole located at −45° position was benefit for cooling, and cooling effectiveness would increase further when spherical cavity diameter was enlarged.

面向小粒蔬菜种子的气吸排种器排种性能试验

Vegetable precision planting agronomy is suitable for my country's current vegetable planting system, and the air-suction vegetable precision planter is currently the most important work tool in my country. This paper designs a kind of air-absorbing vegetable precision sower for the problems of small vegetable seeds with small grains, poor mobility and high difficulty in achieving uniform sowing of small seeds. First, Fluent software is used to simulate and analyze the flow field of the air chamber in the seed metering device, and the pressure and velocity of the fluid in the air chamber are analyzed. Through the comparison of the pressure distribution cloud chart and the velocity distribution cloud chart, the influence of different apertures, holes, vacuum degree, and gas chamber depth on the flow field of the gas chamber is analyzed. The air suction seed discharger test bench was set up and orthogonal test was carried out, and the test results showed that the optimal parameter combination was 3.5 kPa vacuum degree of the air chamber, 2.4 mm diameter of the type hole, and 18 r/min rotational speed of the seed discharging disk. The high-speed photographic test was carried out under the optimal parameter combination, and the results showed that leakage of suction, adsorption of 1 seed, and adsorption of multiple seeds appeared in the process of suction, and it is important for the development of the air suction precision machine for small seeded vegetables with better performance. The results showed that the phenomenon of leakage, adsorption of 1 seed and adsorption of multiple seeds occurred in the process of seed suction, which provided a reference basis for the development of a better performance of the air-absorption precision planter for small seeds.

Mathematical Modelling and Optimization of Seed Metering Unit Performance in Precision Peanut Seeding

The objective of this study was to determine, develop mathematical models, and optimize the in-row seed distribution uniformity performance of a vacuum-type seed metering unit in peanut seeding under different operating conditions. The greased belt stand trials based on the Central Composite Design (CCD) were. Quality of feed index, multiple index, miss index, precision, and coefficient of precision were examined as dependent variables, while the peripheral speed of the seed plate, hole diameter of the seed plate, and vacuum pressure were selected as independent variables. Based on the analysis of experimental data from five different levels of each independent variable, performed using the CCD, a meaningful mathematical model was developed in cubic form for the quality of feed index for peanut seeding, and the model was optimized. The ideal conditions were determined from the model as 0.079 ms−1, 6.94 mm, and 7.07 kPa for peripheral speed of the seed plate, hole diameter, and vacuum pressure, respectively. Based on the findings, quality in seeding by selecting the parameters that affect the performance of precision peanut seeding can be enhanced, resulting in valuable information that can be used as a useful guide to farmers, machine manufacturers, and researchers.

Experimental Determination of Tensile Stress Concentration Factors of 3D-Printed PLA Polymers: Fillet Radius, Hole Diameter, and Infill Density

3D-printing technology is being used as a regular approach in prototyping and the production of machine components. However, despite their metallic counterparts, there are many issues including infill pattern, density, and stress concentration coefficient in 3D printing that are not well-defined. The infill density plays a significant role in the printing time and mechanical properties of the printed objects. On the other hand, like metallic materials, changing geometry, such as fillet radius and hole alters the strength of the printed elements. In this work, experimental works have been conducted to determine the effect of infill density on the tensile strength of 3D printed elements. Furthermore, various standard specimens for tensile testing have been prepared to investigate the effects of fillet radius and in-plane hole diameters on the tensile strength of PLA 3D-printed elements with different infill density. Using the experimental results, the tensile stress concentration coefficients as a function of fillet radius, hole diameters, and infill density have been determined. The results of the present work can be used as a guideline for analytical design and manufacturing 3D printing objects.

Development of the Design of Plate with Variable Diameters of Holes and Its Impact on Meat-Grinding Quality and Efficiency

Meat-grinder plates are critical for efficiently processing meat, significantly influencing the grinding process. This study aimed to develop a meat-grinder plate with variable diameter holes and assess its impact on ground meat quality and processing efficiency. Various meat types (beef, horse meat, mutton, chicken, and pork) were processed using both plate designs: a control plate with a constant hole diameter of 12 mm and a developed plate with featured holes increasing in diameter from periphery to center (8 mm–12 mm–16 mm). The results demonstrate that the developed plate significantly improves the WBC of minced meat, with notable increases in beef (58.3% vs. 57.7%), horse meat (61.8% vs. 56.2%), chicken (51.0% vs. 49.1%), and pork (46.1% vs. 43.6%), indicating a more homogeneous particle size distribution. Yield stress, a critical factor influencing the rheological properties of minced meat, also showed substantial improvements, particularly in poultry (18.9% increase) and pork (31.3% increase). The variable hole design produced a higher proportion of intermediate-sized particles, contributing to a more cohesive texture and potentially enhancing the binding properties of processed meat products. Theoretical calculations based on the Hagen–Poiseuille equation and empirical data confirmed that the new plate design increases the grinder’s productivity by 50%, with average throughput rising from 150 kg/h to 225 kg/h. Additionally, the developed plate reduced power consumption by up to 7.3%, particularly in horse meat processing, highlighting its cost effectiveness for industrial applications. These findings suggest that the variable diameter hole plate design offers substantial improvements in ground meat quality and processing efficiency, with potential implications for industrial meat-processing operations.

曲柄摇杆式深施机构的设计与施肥性能试验研究

In response to the poor fertilization performance of the deep application mechanism of the deep application liquid fertilizer applicator under multiple parameters, the fertilization variation of the crank rocker deep application mechanism under multiple working parameters is explored. To obtain the fertilization variation of the crank rocker deep application mechanism, a fertilization performance test bench for the crank rocker deep application mechanism is developed. On this test bench, the crank speed, liquid pump pressure, and spray hole diameter are used as experimental factors, and fertilizer application rate is used as experimental indicators. A composite design scheme of rotation center is adopted to establish a relationship model and response surface diagram between experimental influencing factors and influencing indicators. Design Expert 8.0.10 software is used to analyze and optimize the experimental data. The optimal results are a crank speed of 145.80 r/min, a liquid pump pressure of 0.25 MPa, a spray hole diameter of 3.02 mm, a fertilizer application rate of 28.6 mL, and a fertilizer loss rate of 1.9%. At this time, the fertilization performance of the mechanism is optimal. This parameter combination is applied for testing and verification to verify its rationality. The results can ensure that the crank rocker deep application mechanism has good working performance when working under multiple parameters, providing theoretical reference for designing deep application liquid fertilizer machines with simple structure and optimal fertilization performance.

Photonic Crystal Fiber Based on Surface Plasmon Resonance Used for Two Parameter Sensing for Magnetic Field and Temperature

This paper presents a photonic crystal fiber (PCF) sensor that can be used to measure the temperature and magnetic field simultaneously, and to monitor the changes in them in the environment. When we designed the fiber structure, two circular channels of the same size were added to the fiber to facilitate the subsequent addition of materials. A gold film is added to the upper channel (ch1), and the channel is filled with a magnetic fluid (MF). The sensor can reflect changes in the temperature and magnetic field strength. The two channels containing MF and PDMS in the proposed fiber are called ch1 and ch2. The structure, mode and properties (temperature and magnetic field) were analyzed and discussed using the finite element method. By using the control variable method, the influence of Ta2O5 or no Ta2O5, the Ta2O5 thickness, the diameter of the special air hole, the distance from the fiber core and the distance between them in the displacement of the loss spectrum and the phase-matching condition of the coupling mode were studied. The resulting maximum temperature sensitivity is 6.3 nm/°C (SPR peak 5), and the maximum magnetic field sensitivity is 40 nm/Oe (SPR peak 4). Because the sensor can respond to temperature and magnetic field changes in the environment, it can play an important role in special environmental monitoring, industrial production and other fields.

Meta-regression of idiopathic full-thickness macular holes diameter and anatomical closure rate: Implications to intraoperative technique

PurposePrimary surgery failure of macular holes causes poor visual acuity outcomes. Several studies indicate that small-medium idiopathic full-thickness macular holes (iFTMH) have consistent and high anatomical closure rates after vitrectomy and internal limiting membrane (ILM) peeling, regardless of iFTMH diameters. However, there is no systematic analysis examining the relationship between iFTMH diameters and anatomical closure rates. MethodsIn this systematic review and meta-regression, we searched PubMed, Embase, and Web of Science databases on October 24th, 2022. We included studies regarding iFTMH, with ILM peeling/inverted flap technique, long-lasting gas tamponade, and face-down position after surgery. Univariable meta-regression with a restricted cubic spline model and component-plus-residual plot after covariables adjustment were used to explore non-linear association. ResultsA total of 7257 participants from 19 randomized controlled trials and 49 observational studies were included in this meta-analysis. In ILM peeling group, every 100-μm increment in diameter was associated with a 3.8 % (95 % confidence interval [CI], 1.8%–5.7 %, P < 0.001) relatively lower anatomical closure rate. Yet, among studies using the inverted flap technique, baseline iFTMH diameter was not associated with a lower anatomical closure rate (0.2 %, 95%CI, −4.2 %–4.5 %, P > 0.9). The restricted cubic spline model and component-plus-residual plot controlling for age, sex, and symptom duration prior to surgery showed no evident non-linearity in both surgical techniques. ConclusionsThe iFTMH diameter is linear and inversely associated with the anatomical closure rate after the ILM peeling technique, but not with the inverted flap technique. The present study supports the use of advanced techniques, e.g., inverted flap technique, in small-medium iFTMH to improve anatomical closure rates.

Dual-window polarization filtering characteristics of rectangular photonic crystal fibers

This paper presents a photonic crystal fiber (PCF) polarization filter with a square array arrangement of gold film fillings, allowing for filtering at dual wavelengths. The paper analyzes the dispersion characteristics and loss properties of this structure and optimizes the structural parameters through adjustments to achieve the best performance. At 1310 nm, the confinement losses of x and y polarization fundamental modes are 903.54 dB/cm and 30.51 dB/cm, respectively; at 1640 nm, the confinement losses of y and x polarization fundamental modes are 479.02 dB/cm and 88.72 dB/cm, respectively. The corresponding filtering bandwidths are 390 and 350 nm, while the full width half maximum (FWHM) is 59.56 nm, indicating excellent selectivity and resolution of the filter. The performance metrics, such as confinement loss, extinction ratios, and bandwidth, are compared in the paper with those reported for other filters. Additionally, the study also analyzed the filter’s performance under varying manufacturing tolerances of gold film thickness and air hole diameter by 5%, revealing that the filter’s performance remains stable and feasible even in the presence of errors.

Creation of a Systematic Interdental Brush Set Based on the Passage Hole Diameter (PHD) - An In-Vitro Study.

This study aimed to develop a systematic interdental brush set with size distribution based on the passage hole diameter (PHD), addressing existing gaps in size selection criteria for effective interdental cleaning. In the first step, an interdental brush set that ascends stepwise according to the PHD value was envisioned. The study was divided into three phases: (i) in-vitro determination of PHD values of a currently existing assortment on the market by 13 calibrated dental professionals, (ii) in-vitro assessment of forces during insertion, and (iii) creation and evaluation of new prototypes for missing or non-matching PHD sizes. Intra- and inter-rater reliability, assessed with the intraclass correlation coefficient (ICC), as well as insertion forces and PHD sizes at all stages were reported. In the existing range, three interdental brushes fitting the desired PHD sizes were initially identified. Mean insertion forces between 0.3 and 1.7 N were documented based on raters' PHD choices. Two additional rounds of measurements with prototypes adapted in diameter and shape were necessary, particularly for PHD values of 1.4, 2.3 and 2.6. High intra- and inter-rater reliability was observed throughout the study (ICC > 0.95), ensuring consistent evaluations. After three rounds of assessments, a prototype was successfully identified for each targeted PHD value in the systematised set, showcasing reliable sizing and insertion forces. Using a structured approach, a comprehensive interdental brush set was developed with reliable PHD sizing and moderate insertion forces. The verification of size reliability through measurements by dentists represents a novelty in development and underlines the importance of accurate brush size selection for optimal biofilm control. Whether a systematic set based on the PHD value offers added value for clinical practice, and at what intervals, must be demonstrated in further studies.