Fiber Parameters Research Articles

Gender-related Differences in Rat Sciatic Nerve Regeneration after Autoplasty and Intraoperative Electroneurostimulation

INTRODUCTION. According to the literature, intraoperative electrical neurostimulation (IES) after autoneuroplasty (AN) accelerates the regenerative growth of axons. It is unknown whether sexual dimorphism occurs in peripheral nerve regeneration after AN and with single-dose IES. AIM. To identify possible gender-related differences in the regeneration of the sciatic nerve (SN) after AN resection of the defect of its tibial portion and a single IES in mature rats. MATERIALS AND METHODS. 72 male (n = 39) and female (n = 33) rats underwent resection and AN of the tibial portion of the SN. Series 1 — non-stimulated control, series 2 — IES session 40 minutes. The tibial functional index (TFI) was calculated from the paw prints; Histomorphometric parameters of myelinated nerve fibers (MF) of the tibial nerve (TN) were determined. RESULTS AND DISCUSSION. In series 1, 2 months after surgery, males were found to have higher values of the numerical density of MVs of the WBN and axon diameters (DA) than in females. After 4 months, YES and MV diameters are larger in females. After 6 months, females have greater myelin sheath (MS) thickness. TFI in series 1 decreases towards the end of the experiment, especially in males. In series 2, 2 and 4 months after surgery, in females the DA, MS, and MF diameters were greater than the values in series 1; after 6 months, only MS and MF diameters were greater. In series 2 males, 2 and 4 months after surgery, the MS and MF diameter are greater than in series 1, and after 6 months, all dimensional parameters in series 2 males are higher than in series 1 males. TFI in series 2 is greater than the values in series 1 and increases towards the end of the experiment, especially in males. CONCLUSION. 2 months after AN, the growth and differentiation of nerve fibers in males is faster than in females, then the differences are inverted. Despite the increase in histomorphometric indicators of regeneration, in unstimulated animals, by the end of the experiment, TFI decreases, especially in males. In stimulated rats, compared to unstimulated ones, the morpho-functional indicators of regeneration at all periods of the experiment are better, to a greater extent in males.

Toxicity of size separated chrysotile fibres: The relevance of the macrophage-endothelial axis crosstalk.

Asbestos minerals have been widely exploited due to their physical-chemical properties, and chrysotile asbestos has accounted for about 95% of all asbestos commercially employed worldwide. The exposure to chrysotile, classified like other five amphibole asbestos species as carcinogenic to humans, represents a serious occupational and environmental hazard. Nevertheless, this mineral is still largely employed in about 65% of the countries worldwide, which still allow its "safe use". The complex mechanisms through which the mineral fibres induce toxicity are not yet completely understood. In this regard, the morphometric parameters of asbestos fibres (e.g., length, width, aspect ratio) are known for their fundamental role in determining the degree of pathogenicity. In this context, the potential toxicity of short chrysotile fibres remains widely debated due to the contradictory results from countless studies. Thus, the present study investigated the different toxicity mechanisms of two representative batches of short (length ≤5 µm) and long (length >5 µm) chrysotile fibres obtained by cryogenic milling. The fibre doses were based upon equal mass and size, since due to chrysotile ability to form bundles, it was not possible to calculate the number of fibers applied per cell. The cytotoxic, genotoxic, and pro-inflammatory potential of the two size-separated chrysotile fractions was investigated on human THP-1-derived macrophages and HECV endothelial cells, both separately and in a co-culture setup, mimicking the alveolar pro-inflammatory microenvironment, in time course experiments up to 1 week. Both chrysotile fractions displayed cytotoxic, genotoxic, and pro-inflammatory effects, with results comparable to the well-known damaging effects of crocidolite asbestos, or higher, as in the case of the longer chrysotile fraction. Furthermore, in presence of HECV, fibre-treated macrophages showed prolonged inflammation, indicating an interesting crosstalk between these cells able to sustain a low-grade chronic inflammation in the lung. In conclusion, these results help to shed light on some important open questions on the mechanisms of toxicity of chrysotile asbestos fibres.

Decoupling the Effects of Temperature, Strain, and Refractive Index in Long-Period Fiber Grating Used for Epoxy Resin Cure Monitoring

Epoxy resins are widely used in the manufacture of composite materials for a wide range of applications. Control of the curing process is an important consideration in ensuring product quality and minimizing production times. The curing of epoxy resin is associated with temperature, strain, and refractive index changes but it is difficult to monitor these quantities individually and hence difficult to achieve accurate control of the curing process. One promising approach for monitoring these quantities is the use of long-period fiber gratings (LPFG). We analyze the spectral response of a LPFG in epoxy resins to temperature, strain, and refractive index. Wavelength shifts and dip amplitudes of cladding mode notches are monitored and are used to decouple temperature, strain, and refractive index for gratings in air, liquid, and hardened resins. The three measurands are found from wavelength shifts and dip amplitudes, employing multiplication by a weighted pseudo-inverse matrix assuming linear dependences between the spectral and external parameters. We propose a new model to describe the influence of fiber parameters and external refractive index, temperature, and strain on the spectral behavior of long-period fiber gratings in epoxy resins during hardening. The results obtained can be utilized for multiparameter cure process monitoring of epoxy resins by using long-period fiber gratings.

Obesity and hypoxia have differential effects on myocardial innervation in the right ventricle of the male mouse heart.

Obesity, along with hypoxia, is known to be a risk factor for pulmonary hypertension (PH), which can lead to right ventricular hypertrophy and eventually heart failure. Both obesity and PH influence the autonomic nervous system (ANS), potentially aggravating changes in the right ventricle (RV). This study investigates the combined effects of obesity and hypoxia on the autonomic innervation of the RV in a mouse model. Male C57BL/6N mice were subjected to a control diet (CD) or a high-fat diet (HFD) for 30 weeks, with subsets of the mice exposed to chronic normobaric hypoxia (13% O2) during the final 3 weeks. Light and electron microscopic stereology was used to quantify various parameters of nerve fibres innervating the RV myocardium. HFD-induced obesity significantly increased the total length of nerve fibres and axons in the RV under normoxic conditions, indicating hyperinnervation. Quantitatively, the length density of nerve fibres per unit volume of RV (unit: x10-3 µm-2) was similar in CD (0.158 ± 0.04), CD-Hyp (0.176 ± 0.06) and HFD-Hyp (0.147 ± 0.05). In contrast, in HFD the length density of nerve fibres showed higher values 0.206 ± 0.054. The total length of nerve fibres increased by 67% from 2.61 m ± 0.77 m in CD to 4.37 m ± 1.51 m in HFD. The total length of axons increased by 80% from 8.87 m ± 2.75 m to 15.95 m ± 4.62 m. However, when obesity was combined with hypoxia, the total axon length was significantly reduced by 27% in HFD-Hyp compared with HFD. In addition, the mean number of axon profiles per nerve fibre profile decreased from 3.44 ± 0.68 in HFD to 2.95 ± 0.43 in HFD-Hyp. Interestingly, chronic hypoxia alone did not significantly alter RV innervation but led to RV hypertrophy, independent of the diet. The attenuation of obesity-induced hyperinnervation by hypoxia suggests a complex and potentially antagonistic interaction between these conditions. In conclusion, obesity induced by a HFD caused hyperinnervation of the RV, whereas chronic hypoxia alone did not significantly alter RV innervation. Surprisingly, chronic hypoxia attenuated the obesity-induced changes in RV innervation. These findings indicate that the effects of obesity and hypoxia-induced PH on RV innervation are distinct and potentially antagonistic.

Effect of Polypropylene and Straw Fiber Materials on the Unconfined Compressive Strength of Tailings and Wasted Stone Mixed Backfill.

Ensuring the mechanical performance of backfill materials while reducing cementation costs is a key challenge in mine backfill research. To address this, fiber materials such as polypropylene (PP) fiber and rice straw (RS) fiber have been incorporated into cement-based mixtures for mine backfilling. This study investigates the effects of PP and RS fibers on the mechanical properties, flow characteristics, and microstructure of Tailings and Wasted Stone Mixed Backfill (TWSMB). A series of orthogonal experiments were designed to evaluate the influence of variables, including the cement-sand ratio, solid mass concentration, wasted stone mass concentration, fiber content, and fiber length on the TWSMB properties. The results indicate that the influence of cement-sand ratio and solid mass concentration have a more significant impact on strength than fibers, though the fibers show a stronger effect than the wasted stone mass concentration. Both fiber types enhanced the strength of the specimens, with PP fiber exhibiting a stronger reinforcing effect than RS fiber. Furthermore, the effect of PP fiber content was more pronounced than that of fiber length, whereas the opposite trend was observed for RS fiber. The optimum fiber parameter levels were determined for each type: PP fiber performed best at a mass concentration of 1.5% and a length of 6 mm, while RS fiber showed optimal performance at a mass concentration of 1.0% and a length of 5-10 mm. Macroscopic damage analysis indicated that the structural integrity and residual compressive strength of the TWSMB specimens were preserved even after surpassing the ultimate compressive strength, due to the crack-bridging effect of the fibers. Microstructural analysis showed that PP fiber-reinforced specimens exhibited a dense structure formed through reactions with other hydration products. In contrast, the surface of RS fibers was nearly fully encapsulated by hydration products, resulting in the formation of a physical skeleton structure. This study provides new insights into minimizing cement consumption and reducing backfilling costs in mining operations.

High-performance chalcogenide fiber bundle for mid-wave infrared imaging.

Flexible infrared image fiber bundles (FBs) are capable of delivering thermal images of areas that are difficult for ordinary thermal cameras to access while making the imaging systems compact and lightweight. Thus, FB-based thermal imaging systems show great potential in some important applications, such as infrared endoscopy, aircraft infrared warning, and satellite remote sensing. In most applications, FBs are required to have high overall transmittance (OT) and high spatial resolution (R), but the fabrication of such high-performance FBs is still a challenge. In this work, we demonstrate a new design of flexible mid-wave infrared chalcogenide FB with high OT and decent R by optimizing the composition of glass cladding and geometric parameters of single fibers. The FB is fabricated by a modified approach combining the stack-and-draw technique and layer-stacking method, and the thermal image delivery performance of the FB is comprehensively characterized. It is shown that the core diameter (d core) and core/cladding diameter ratio (R cc) of single fibers can be balanced to reduce leakage of the light propagating in the single fibers while making the FB retain a reasonably high filling factor. Thus a high-performance FB can be achieved. The fabricated FB consists of 124,200 single fibers featuring an As40S60 core, an As38.9S61.1 cladding, and a polyetherimide (PEI) protective coating, with a dcore of ∼22.8 µm and an Rcc of 0.8. It has a length of ∼52 cm and a filling factor of ∼50.2%. The FB presents excellent thermal image delivery performance, including an OT of 40.5%, a single-fiber loss of 1.71 dB/m at 4.6 µm, and an R of 20.2 lp/mm, which compares favorably to previously reported FBs. These findings provide new insights for the development of high-performance thermal imaging FBs and lay a foundation for their practical applications.

Damage Evolution Characteristics of Steel-Fiber-Reinforced Cellular Concrete Based on Acoustic Emission

In order to investigate the steel fiber parameters on the damage characteristics and crack evolution of cellular concrete materials, uniaxial compression–acoustic emission combined tests were carried out on steel-fiber-reinforced cellular concrete (SFRCC) with different steel fiber contents (0%, 0.5%, 1%, 1.5%, and 2%) and different porosities (10% and 20%). The material damage evolution characteristics were analyzed by acoustic emission parameters and IB values, and the crack types were identified using Gaussian mixture clustering method (GMM) pairs. The results show the following: the inclusion of steel fibers increased the compressive strength of cellular concrete by 19.8~46.3% at 10% porosity, and by 37.1~102.2% at 20% porosity; the addition of steel fibers significantly increased the density and intensity of the acoustic emission signals; the decreasing tendency of the IB value at the peak stress slowed down with the increase in the amount of steel fibers, and the steel fibers could effectively inhibit the crack development; crack classification results show that the proportion of shear cracks in all stages of cellular concrete increased significantly after the addition of steel fibers.

Comparative Analysis of Yield and Fibre Traits in Newly Developed Bt and Non-Bt Cotton Hybrids

Aims: Cotton is a major fibre crop for textile industry and farmers in the world. Despite its tremendous importance, productivity constraints are still present. To eliminate productivity problem and increase the yield, the present investigation focused on developing new Bt cotton hybrids with better yield and fibre characteristics through estimation of heterosis in different combination of Bt and Non Bt parents. Study Design: Randomized block design with three replication was used to conduct the experiment. Place and Duration of Study: The experiment was conducted at Cotton Research Unit, Dr. PDKV, Akola, Maharashtra, during Kharif 2019 & 2020. Methodology: The five diverse parents were crossed with one another as making four crosses of Bt x Bt parents and four crosses of Non-Bt x Bt parents. Eight F1 hybrids then were evaluated for heterosis performance for different morphological, yield, yield contributing traits and fibre traits with standard checks i.e. PDKV JKAL 116 and Ajeet 155 in Kharif 2020. Results: Results showed that for seed cotton yield (kg/ha), the cross AKH 09-5 × ICAR-CICR Rajat Bt recorded highest 12.30% standard heterosis over the check PDKV JKAL 116. Significant standard heterosis of 35.83% and 34.36% was observed for no. of bolls per plant over both the checks. While the cross ICAR-CICR 081 Bt × ICAR-CICR Rajat Bt was found to be most heterotic for fibre parameters. Conclusion: It was found that the Non-Bt × Bt crosses performed better for yield and its contributing trait than Bt × Bt crosses, while Bt × Bt crosses did gave good results for fibre quality parameters. Understanding the genetics behind, can be beneficial for the farming community.

Hybrid hexa-octagonal photonic crystal fiber with excellent guiding properties for sensing and communication applications

Abstract A novel hybrid hexa-octagonal photonic crystal fiber (PCF) is designed by integrating a hexagonal arrangement of elliptical air holes in the core using soft glass and an octagonal lattice of circular air holes in the cladding. This study presents a comparative analysis of the fiber parameters, including confinement loss, non-linearity, effective area, birefringence, and chromatic dispersion, for two configurations: (i) hybrid hexa-octagonal PCF with a horizontal arrangement of air holes in the core, and (ii) hybrid hexa-octagonal PCF with a vertical arrangement of air holes in the core. Both configurations are examined by varying the pitch size, arrangement, and shape of air holes while maintaining identical design and operational features. Simulations are conducted using the full vector finite element method (FEM). Numerical results indicate that the confinement loss for vertically and horizontally arranged air holes is 1.098 × 10−5 dB km−1 and 1.0743 × 10−5 dB km−1, respectively. High birefringence values of 0.07366 and 0.00434, and chromatic dispersion values of −3404.665 ps nm−1 km and −3391.6705 ps nm−1 km, respectively, are obtained at an operating wavelength of 1.55 µm, making the fiber suitable for sensing and communication applications. The designed hexa-octagonal PCF has potential applications in the fiber optic sensing due to its assorted features.

Concreto reforçado por fibras metálicas helicoidais

The purpose of adding metallic fibers (filiform elements) to cementitious matrices is to increase the toughness of these brittle materials. The lateral confinement technique, using spiral reinforcement or stirrups, is capable of increasing the compressive strength of the confined core of cement matrices. Thus, this work aimed to use helical metal fibers (two-dimensional elements) with the aim of increasing both the toughness and the compressive strength of concrete. So, an experimental program was carried out in order to determine the compressive strength and residual strength (toughness index) of five types of concrete, varying the volume fraction of helical metal fibers from 0 (reference concrete) to 2%, every 0.5%. The results obtained indicated that the helical metal fibers were able to increase the residual strength of concrete by up to 30% (concrete with 2% of helical fibers), these increases being linear and directly proportional to the amount of fibers added, but they did not have a significant influence on the compressive strength of the final products. However, more tests need to be carried out, varying the helical fiber parameters, to confirm these preliminary results.

Comparing the Randomized Trial Outcomes of 3D Low-Light Intensity-Assisted and Traditional Eyepiece-Assisted Pars Plana Vitrectomy for Rhegmatogenous Retinal Detachment.

Pars plana vitrectomy (PPV) is a primary surgical method for rhegmatogenous retinal detachment (RRD). The introduction of the 3D head-up system has provided ophthalmologists with a new surgical experience. This study aimed to compare the surgical outcomes between 3D low-light intensity-assisted and traditional eyepiece-assisted PPV for RRD. A prospective randomized controlled design was employed to compare the surgical outcomes of 3D low-light intensity-assisted and traditional eyepiece-assisted PPV for RRD. The optical intensity parameters of optical fibers and chandeliers were set according to the minimum lighting standard for 25-G PPV. Surgery duration and intraoperative conditions were documented. Post-surgery, the light intensity of the optical fiber and chandeliers during surgery was measured using a photometer. Patients were followed up for six months to assess their postoperative recovery. Statistical analysis was performed using SPSS 26.0 software, with p < 0.05 indicating statistically significant differences. There was no statistically significant difference between the two groups in baseline data (p > 0.05). PPV was completed in all patients, and there was no statistically significant difference in surgery time between the two groups (p > 0.05). The optical fiber and chandelier light intensity in the 3D group were significantly lower than those in the eyepiece group and the difference being statistically significant (p < 0.001). Six months after surgery, the retinal attachment rate was 100%. Post-surgery, both best corrected visual acuity (BCVA) and intraocular pressure (IOP) were significantly higher than presurgery levels. There were no significant differences between the two groups in terms of retinal attachment rate, BCVA, IOP, and flash electroretinogram (p > 0.05). Compared to the traditional eyepiece, the 3D head-up system can effectively complete surgery under lower illumination intensity. The anatomical restoration and functional success of the retina after surgery are equivalent.

Stability of vacuum-packed peach palm (Bactris gasipaes Kunth) flours obtained by dehydration and freeze-drying during accelerated storage

This paper evaluated the stability of vacuum-packed peach palm flours obtained by dehydration and freeze-drying during accelerated storage. For the elaboration of the flours, peach palm fruits (Bactris gasipaes Kunth var. gasipaes), harvested in the Eastern region of Ecuador, were used. The in natura fruits were washed with running water and disinfected. Before treatment, the fruits were scalded and cooled in an ice-water bath. Then, they were peeled, seeded and chopped. The dehydrated and lyophilized materials were pulverized in a blade mill and vibrated sieved for 10 min. Moisture content, ash, crude fiber, fat, carbohydrates, proteins and rheological parameters were determined for the flours. The flours were vacuum packed and stored at 30, 40 and 50 ºC. During accelerated storage, the peroxide value (POV) was determined. The results of this determination were subjected to linear regression analysis as a function of time. The parameters of the Arrhenius model (k and Ea) for the variation of the POV and the temperature acceleration factor (Q10) were also determined. The variation of the POV in both flours showed a similar behavior during accelerated storage, without there being, in general, differences (p ≤ 0.05) regarding the increase of the POV. In all cases, this POV increase during accelerated storage was adjusted to a zero-order reaction and linear models were obtained to estimate the variation of this parameter for each combination of flour and temperature. The Q10 values for the POV variation ranged between 1.05 and 1.29, regardless of the type of flour.

Analysis of the Deburring Efficiency of EN-AW 7075 Aluminum Alloy Parts with Complex Geometric Shapes Considering the Tool Path Strategy During Multi-Axis Brushing.

The paper presents the results of an analysis of the effect of brushing on the edge condition of workpieces with complex geometric shapes, formed during milling, on a five-axis DMU 100 monoBLOCK machining center. A set of EN-AW 7075 aluminum alloy specimens with curvilinear edges requiring multi-axis machining was prepared. The change of edge condition after the milling process was realized using Xebec tools with flexible ceramic fibers. The effects of brush fiber type and parameters related to tool design were analyzed. Different brushing strategies were employed on the five-axis machining center. It was shown that, for curvilinear edges, there were different effects for concave and convex edges depending on the employed tool strategy, including the type of tool, its configuration, and its orientation towards the workpiece. For a lead angle of β = 0°, the machined edge was characterized by variable chamfer widths, in spite of maintaining other machining parameters constant. The use of a lead angle β > 0 produced a stable edge with repeatable characteristics. The range of fiber interaction increased with increasing the lead angle and fiber working length.

Effects of the Hot-Drawing Process on the Pore Parameters, Gas Absorption and Mechanical Performances of Activated Carbon-Loaded Porous Poly(m-Phenylene Isophthalamide) Composite Fibres.

Poor breathability, inadequate flexibility, bulky wearability, and insufficient gas-adsorption capacity always limit the developments and applications of conventional chemical protective clothing (CPC). To create a lightweight, breathable, and flexible fabric with a high gas-absorption capacity, activated carbon (AC)-loaded poly(m-phenylene isophthalamide) (PMIA) porous composite fibres were fabricated from a mixed wet-spinning process integrated with a solvent-free phase separation process. By manipulating the pore parameters of as-spun composite fibres, the exposure-immobilization of AC particles on the fibre surface can offer a higher gas-absorption capacity and better AC-loading stability. To improve the mechanical properties of AC-loaded porous as-spun fibres and further optimize the pore-locking structures, the impact of the hot-drawing process on the evolution of pore parameters and the corresponding properties (including the gas absorption capacity, the mechanical performance, and the stability of AC particles during loading) was clarified. After the hot-drawing process, the inhomogeneous pore morphologies composed of mesopores/micropores from as-spun fibres changed into homogeneous and decreased mesopores. With the decrease in structural defects in homogeneous morphologies, the tensile strength of AC-loaded PMIA porous-drawn fibres increased to 1.5 cN/dtex. Meanwhile, the greater total pore volume and specific surface area after hot drawing also maintained the gas-absorption capacity of drawn composite fibres at 98.53 mg/g. Furthermore, the AC-loaded PMIA porous composite fibres also showed comparable performance to the commercial FFF02 absorption layer in terms of static absorption behaviour for different gas molecules and absorption-desorption multi-cycling evaluations. In addition, due to the size reduction in mesopores after the hot-drawing process, the loading stability of AC particles in the stretched composite fibres was more substantial.

Implications of compressive loading of the stomach wall: Interplay between mechanical deformation and microstructure.

During gastric surgery, the stomach wall is compressed with clamps and sutures or staple lines. These short- and long-term deformations can severely compromise the integrity of the tissue and make it difficult for the stomach wall to respond and remodel to the new loading conditions. Consequently, serious intra- and postoperative complications such as the formation of leaks during bariatric surgeries, can be associated with these immense tissue deformations. Hence, the study aimed to investigate the effects of compressive loading of the stomach wall in the radial direction. This was done by macroscopic mechanical loading of the stomach wall in each region of the stomach and evaluating the microstructural changes inflicted in the tissue. For this purpose, several imaging techniques were used, i.e., a histological analysis, second-harmonic generation microscopy, and X-ray micro-computed tomography. The combination of these three methods allowed us to investigate the gradual compression of the different stomach layers as well as the local reorientation and deformation of the main microstructural components, e.g., collagen fibers and muscle bundles. Importantly, this study found that the collagen bundles in the stomach wall straighten and reorient toward the circumferential-longitudinal plane and partially fan out with increased radial compressive deformation. The 3D scans of the stomach wall indicated a deterioration of the blood vessels and buckling of the mucosal glands due to compression. Statement of significance Unfortunately, little is known about the load transfer in the stomach wall during gastric surgery and the associated deformations on the macro- and microscale. The present study investigates the structural changes of the stomach wall, its layers and the inherent biological building blocks using histology, multi-photon microscopy, and micro-computed tomography. For the first time, the layer-specific response to stepwise radial compression of the stomach wall was studied, the related collagen fiber parameters were estimated, and a 3D sample structure was visualized. This clinically-oriented study links the structural changes within the wall to the postoperative remodel- ing process and the irreversibly altered gastric motility, thereby underscoring its relevance to the field of biomedical engineering, e.g., the development and improvement of surgical instruments.

Effect of steel fibers on the stress–strain behaviour of aligned steel fiber ultra-high performance concrete under uniaxial compression

The mechanical properties of ultra-high performance concrete (UHPC) can be significantly enhanced by aligning the fibers. Aligned steel fiber UHPC (ASF-UHPC) was fabricated using a uniform magnetic field, yet the corresponding stress-strain relationship has not been extensively studied, hindering accurate calculations. To address this gap, ASF-UHPC was prepared and subsequently subjected to CT scans and uniaxial compression tests to investigate its stress-strain behavior. The analysis of failure mode and stress-strain curves revealed distinct anisotropic characteristics in compressive stresses and fiber distributions. Various steel fiber parameters, including the alignment orientation, volume fraction, and length, were systematically analysed to assess their impact on the material properties. A unit-cell model was developed to elucidate the influence of the fiber alignment orientation on UHPC performance. The results demonstrate that a parallel fiber alignment significantly enhances the elastic modulus, albeit with a Poisson ratio similar to that of the matrix, owing to the limited lateral confinement. Conversely, perpendicular fiber alignment restrains lateral deformation, enhancing the material strength and toughness. Randomly distributed fibers offered a degree of horizontal confinement, whereas inclined fibers induced horizontal thrust, leading to excessive lateral deformation and consequent elevation of the Poisson ratio. Finally, predictive equations for UHPC elastic modulus and compressive strength, along with an analysis model for stress-strain characteristics, were refined taking into account the direction of fiber arrangement.

Abstract 4117922: The Role of Combined Renin Angiotensin Aldosterone System Inhibitors (RAASi) Plus Beta Blocker Therapy For Cardiotoxicity Prevention In Patients Under Chemotherapy For Breast Cancer: A Meta-Analysis of Randomized Controlled Trials

Introduction: Anti-neoplastic agents, including anthracyclines and trastuzumab, frequently employed in breast cancer treatment carry on considerable cardiotoxic effects impairing both cardiac chamber and cardiac fiber parameters leading to incident heart failure. In response to this challenging side effect, numerous randomized controlled trials (RCTs) have investigated the cardioprotective efficacy of RAASi and beta-blockers (BBs) in patients undergoing anthracycline and trastuzumab chemotherapy. We aim to perform an updated meta-analysis to elucidate the potential cardioprotective properties of these medications in patients undergoing chemotherapy for breast cancer. Methods: A comprehensive search of the literature was performed through April 2024 on PubMed, EMBASE and Clinicaltrials.gov. In total, data from 4 randomized studies were extracted and analyzed. The primary analysis was the effect of RAASi and BBs on LVEF as well as global longitudinal strain (GLS). Data were analyzed using a random-effects model to derive weighted mean differences (WMDs) and 95% confidence intervals for both LVEF and GLS. Data was analyzed using Review Manager 5.3 (RevMan 5.3) software. Results: In total, data from 248 patients (N = 124 on cardioprotection; N = 124 without cardioprotection) undergoing treatment with anti-neoplastic agents for breast cancer were included. At the end of treatment, patients undergoing cardioprotective therapy demonstrated improved LVEF preservation compared to the control group, (mean difference 2.14 [0.03, 4.25]; P=0.05; I2 = 79%). In addition, patients undergoing dual RAASi + BB therapy showed better GLS preservation compared to control group (mean difference –1.37 [-2.01, -0.72]; P &lt; 0.0001; I2 = 0%). Conclusion: In breast cancer patients undergoing anti-neoplastic regimens comprising anthracycline and trastuzumab, the concomitant administration of RAASi and BBs demonstrated better LVEF as well as GLS preservation upon completion of treatment over those without cardioprotective therapy. These findings shed light on the potential benefit derived from the synergistic effects of RAASi and BBs therapy in safeguarding both cardiac chamber and fiber functions amidst aggressive anti-cancer regimens, although further investigations still need to be conducted.

Analysis of stress-strain curve of POM fiber reinforced concrete

ABSTRACT As a new type of synthetic fiber, polyoxymethylene (POM) fiber has the advantages of high tensile strength, good dispersibility, and high bonding strength with cement interface. It has broad application prospects. However, there is limited research on POM fiber reinforced concrete. In order to provide scientific basis for promoting the application of POM fiber, this paper adopts a combination of indoor experiments and numerical simulations to obtain the axial stress-strain complete curves of POM fiber reinforced concrete with different volume dosages and studies the uniaxial compressive properties of POM fiber reinforced concrete. Finally, the constitutive equation parameters of POM fiber reinforced concrete were fitted using the Guo Zhenhai model, and the optimal fiber content was determined. The results indicate that at a POM fiber content of 1.5 kg/m3, the load-displacement curve exhibits optimal shape with the highest residual strength. With increasing fiber content, compressive stress-strain curve parameters initially increase and then decrease, peaking at 1.5 kg/m3, optimizing the mechanical properties of concrete. POM fiber has minimal impact on initial elastic modulus. Thus, optimal mechanical property enhancement is achieved with 1.5 kg/m3 POM fiber content.

Influence of Optical Fiber Parameters on the Speckle Pattern and Spectral Observation in Astronomy

Optical fibers serve as a bridge to transmit starlight into the spectrograph in fiber spectral surveys. Due to the interference between multiple modes supported within the fiber, a granular speckle pattern appears on the end of the fiber and leads to an uneven and random energy distribution in the spectrum. This effect is called mode noise, which reduces the accuracy of high-resolution spectral detection. This work investigates the influence of transmitted mode numbers on speckle patterns by using fibers with different core diameters and numerical apertures. A reciprocating mechanical scrambler is proposed for suppressing near-field speckles with negligible focal ratio degradation. We use centroid offset and radial power spectrum to quantitatively evaluate the characteristics of the speckles with and without scrambling. Experimental results show that more modes in a fiber with a larger core diameter reduce the centroid offset of the speckle and make the energy distribution more uniform. The mechanical mode scrambler significantly reduces the random centroid deviation caused by speckles, which is more obvious for large-core fibers. The standard deviation of centroid offset in 1000-cycle tests for the 160 µm core fiber is only 0.043 µm, which is one-tenth of that for the 16 µm core fiber. However, in solar spectrum measurement using these fibers, small-core fibers can more easily achieve higher spectral resolution and capture more spectral information. Therefore, large-core fibers are suitable for tasks requiring high accuracy, while fibers with a smaller core diameter should be applied for high-precision spectral measurement.

Characterization of Holmium-Doped Fiber Using AOM and Considering Pair-Induced Quenching and Fiber Length

In this paper, we present the results of an experimental study on the characterization of holmium-doped silica fiber. A standard acousto-optic modulator controls the output power of the ytterbium-doped fiber laser operating at 1134.5 nm and serving as a pump source of the holmium-doped fiber under test. This technique allows us to measure the lifetimes of 5I7 and 5I8 energy levels of Ho3+ ions. The effects of the fiber length and the concentration-dependent pair-induced quenching on the accuracy of the fluorescence lifetime measurement are considered. The results of this study are compared with those obtained using the exponential and Förster decay functions used for such types of measurements. It is demonstrated that the knowledge of two fiber parameters, the pump saturation power and the fluorescence saturation power, together with the fiber absorption spectrum, permits one to obtain the absorption cross-sections at the pump and other key wavelengths, the effective concentration of the active ions, and the quantum efficiency of the fluorescence from the laser level. The results of this study are applicable to the reliable characterization of any type of heavily doped gain fibers and to the further numerical modeling and optimization of fiber lasers.