Fiber Length Research Articles

Influence of fiber concentration and length on the dielectric, mechanical, and thermal properties of maple wood fiber-reinforced polypropylene

Natural fiber-reinforced polymer composites are gaining popularity due to their sustainability and enhanced properties compared to pure polymers. Recently, these composites have been utilized as dielectric materials. In this study, polypropylene (PP) reinforced with maple wood fibers of different lengths (50, 75, and 100 µm) and various fiber concentrations (5%, 10%, 15%, and 20%) were examined. The effects of fiber length and concentration on the dielectric, mechanical, and thermal properties were investigated. All composites exhibited a higher dielectric constant and conductivity than pure PP, along with a lower loss factor. This suggests that adding maple wood fibers generally enhances the dielectric properties. As fiber concentration increases, the dielectric constant tends to rise while the loss factor tends to decrease. TGA results indicated that adding more fibers reduces thermal stability at low temperatures but increases stability at high temperatures. Mechanical testing revealed an increase in strength but a decrease in elongation. However, fiber length did not significantly impact the mechanical properties. SEM analysis showed a uniform distribution of fibers at 5% weight that improves strength, while a 20% weight leads to clustering that weakens the composite.

Effect of curing condition on mode‐I and mode‐II cracking resistance of glass fiber reinforced concrete and their relations with tensile and compressive strengths

AbstractGlass fiber‐reinforced concrete is a favorable material for constructing structures, especially for those placed in watery environments. The concrete in the watery environments can be roughly placed in two conditions, above the water (dry) or under the water (submerged). On the other hand, water bodies can also be categorized as fresh or salt water. In the current study, the effect of fiber length (e.g., plain, 10, 20, and 30 mm), curing environment (e.g., dry, fresh, and saltwater), and age (28, 90, and 180 days) was studied on glass fiber reinforced concrete. The measured mechanical parameters were direct tensile (σt) and compressive (σc) strengths, along with pure mode‐I (KIc) and pure mode‐II fracture (KIIc) resistance. The results show that the tensile strength, mode‐I and mode‐II fracture toughness constantly increase with the increase of fiber length to 30 mm, while compressive strength reduces if fiber length increases by more than 15 mm. The optimum fiber length was obtained as 30 mm (based on tensile data). The trend analysis shows a meaningful relation between the tensile and compressive strength and between the mode I and mode II fracture toughness.

Evaluation of mechanical properties for Ricinus communis L plant fiber/epoxy composite

AbstractThis research explores the mechanical properties of castor oil plant (Ricinus communis L) natural fiber‐reinforced epoxy composites, addressing the need for sustainable materials. Cortex and xylem fibers extracted from castor oil plant residue using a standardized method were used to fabricate unidirectional long fiber and short random fiber composites. Various fiber volume fractions (10 %, 20 %, 30 %, 40 %) and fiber lengths (5 mm to 40 mm) of cortex fibers were tested according to ASTM standards and results showed that fibers of diameters 275 μm to 325 μm, have superior tensile strength (290 MPa to 346 MPa) compared to xylem fibers (90 MPa to 140 MPa). Composites of 40 % volume fraction cortex fibers aligned longitudinally exhibited the highest tensile (76.35 MPa), flexural (121.45 MPa), and impact strength (6.99 kJ/m2) significantly improved compared to the epoxy matrix. For short random cortex fiber composites, the optimal mechanical performance was achieved with 20 mm fibers and a 40 % volume fraction, resulting in the highest tensile strength (32.12 MPa), flexural strength (84.31 MPa), and impact energy (40 J/m). These results highlight the potential of castor oil cortex fibers to enhance the mechanical properties of epoxy composites for various engineering applications.

Development of a set of monosomic alien addition lines from Gossypium raimondii in Gossypium hirsutum toward breeding applications in cotton

BackgroundGossypium raimondii Ulbr is a diploid wild cotton (2n = 26, D5D5) that originated in west-central Peru of South America and possesses desirable characteristics that are absent in the Upland cotton G. hirsutum. Many beneficial genes were lost from G. hirsutum in the process of domestication, leading to a narrowed genetic base and greater vulnerability to biotic and abiotic stresses. This genetic base can be expanded through distant hybridization using the superior genes of G. raimondii.ResultsIn this study, putative hexaploid F1 plants of G. hirsutum - G. raimondii were generated by interspecific hybridization. Analysis of its mitotic metaphase plates revealed the presence of 78 chromosomes, with each of the six chromosome-specific fluorescence in situ hybridization (FISH) probes (3D5, 5D5, 6D5, 7D5, 9D5, and 10D5) of G. raimondii exhibiting bright and distinct signals on its respective pair of chromosomes. Then, the fertile hexaploid F1 plants were continuously backcrossed with G. hirsutum and a set of G. hirsutum - G. raimondii monosomic alien addition lines (MAALs) were developed using SSR markers in successive backcrosses and self-crossing from BC2F1 to BC4F2. These MAALs were confirmed by chromosome-specific anchored SSRs and FISH. This set of MAALs exhibited abundant variation in morphological traits, agronomic characteristics, yield, and fiber quality traits, as well as in drought and salt resistance at seedling stage. Notably, MAAL_9D5 and MAAL_10D5 demonstrated excellent fiber length (FL), fiber uniformity (FU), fiber strength (FS), micronaire value, and fiber elongation (FE); At seeding stage, MAAL_8D5, MAAL9D5, MAAL_10D5, MAAL_12D5, and MAAL_13D5 showed salt resistance potential; while MAAL_1D5, MAAL_3D5, MAAL_4D5, MAAL_7D5, MAAL_8D5, MAAL_12D5, and MAAL_13D5 exhibited drought resistance potential. These MAALs will provide important genetic bridge materials for gene transfer from G. raimondii as well as for the study of Gossypium species genomes and their evolution.ConclusionsA set of Gossypium hirsutum - Gossypium raimondii MAALs were developed and they showed abundant variation in morphological, agronomic, yield, and fiber quality traits, as well as in drought and salt resistance at seedling stage.

Theoretical study on cascade Energy-transfer pumping heavily holmium-doped fluoroindate fiber laser at ∼ 4 μm with high-efficiency

In this article, we propose a cascade pumping scheme that employs 1.945 μm and 1.66 μm fiber laser as the pump sources to realize efficient laser emission at 3.92 μm in the commercially available heavily holmium-doped fluoroindate fibers. Compare to the conventional 888 nm laser diode, longer wavelength pump sources provide higher quantum efficiency, which is critical for the acquisition of high output power at a relatively low input pump power considering the low damage threshold of InF3 glass. Output performance is optimized by conducting detailed investigation on fiber length, output coupler mirror reflectivity and launched pump power. Simulation results show that when employing cladding pump at both 1.945 μm and 1.66 μm, a slope efficiency of 25 % can be achieved with a threshold of 1.6 W for the 1.66 μm pump source. This is attained using a 15 cm-long fiber under a pump power of 5 W at 1945 nm. Furthermore, the maximum optical-to-optical efficiency reaches 11.17 % when considering the total pump power. To our knowledge, the efficiency achieved in this study appears to surpass that of previous works. This research provides a novel approach and valuable guidance for efficient laser output at the important ∼ 3.9 μm wavelength region, for applications in various fields such as free-space communications, remote sensing and medical diagnostics.

Evaluation of piezoresistive response and mechanical performance of self-sensing asphalt concrete mixed with different lengths of carbon fiber

Evaluation of piezoresistive response and mechanical performance of self-sensing asphalt concrete mixed with different lengths of carbon fiber

Pulmonary inflammatory responses and retention dynamics of cellulose nanofibrils.

Cellulose nanofibrils (CNFs) are advanced biomaterials valued for their strength, lightweight nature, and low thermal expansion, making them suitable for diverse industrial applications. However, their potential inhalation risks necessitate thorough safety evaluations. This study investigates the pulmonary inflammatory effects and retention of CNFs following intratracheal instillation in rats. TEMPO-oxidized CNF (CNF1; 11.5 nm × 1.8 μm), mechanically fibrillated CNF (CNF2; 23.9 nm × 2.4 μm), and shorter-fibrillated CNF (CNF3; 21.6 nm × 1.2 μm) were administered at 2.0 mg/kg body weight. Endotoxin contamination was assessed using lipopolysaccharide (LPS) controls. Pulmonary inflammation was evaluated 28 days post-instillation, and lung retention of chemically stained CNFs was tracked for 90 days. Results indicated: (1) CNFs were taken up by alveolar macrophages, but no significant acute inflammation was observed; (2) CNF characteristics, particularly fiber diameter and length, play a key role in influencing lung inflammation responses and determining inflammation sites; (3) endotoxin levels in the CNF dispersions may have limited effects on inflammatory responses; and (4) CNFs persist in lung tissue for extended periods, indicating slow clearance. While immediate inflammatory responses were minimal, the prolonged retention of CNFs in the lungs could contribute to chronic low-grade inflammation. Given the variability in CNF properties influenced by raw materials and manufacturing processes, it is essential to test each CNF type individually, including toxicological endpoints beyond inflammation, to accurately assess their potential health risks.

Correlation of tumoral collagen width with overall survival and tumoral collagen straightness with distant recurrence-free survival in patients with pancreatic ductal adenocarcinoma.

779 Background: Quantitative measurements of fibrillar collagen characteristics has been shown to correlate with survival in several types of malignancy. The aim of this study was to determine whether these characteristics correlate with survival in pancreatic ductal adenocarcinoma. Methods: Patients who underwent pancreatic resection for pancreatic ductal adenocarcinoma at an Allegheny Health Network hospital between 1/1/2019 and 12/31/2023, and for whom archived formalin-fixed paraffin-embedded tumor tissue was available, were included in the study. Clinical and pathologic characteristics were collected from the patient's electronic medical record. Survival data included overall survival (OS), local recurrence-free survival (RFS), and distant RFS. One section of tumor per patient was stained with Picrosirius Red and a representative digital image was obtained with a camera attached to a microscope at 100x magnification. Each image was analyzed with CT-FIRE software to determine averages of collagen fiber width, length, straightness, and angle. Descriptive statistics were initially computed. Log-rank tests were also conducted to compare the OS rate and RFS rate between four different groups (width, length, straightness, angle). Each group was divided into high and low groups, using the mean as cutoff. In the end, multivariate Cox regression was conducted by controlling the confounders including sex, perineural invasion, lymphovascular invasion, and presence of lymph node metastasis to examine the hazard ratios of OS, local RFS, and distant RFS for the four collagen fiber metrics. All statistical analyses were performed via SAS 9.4 under alpha level .05. Results: One hundred three patients met the inclusion criteria. Based on the results of log-rank test, OS was significantly different between high and low collagen width groups, p = .0251. The lower width group had higher survival rate than the upper width group. Also, distant recurrence-free survival was significantly different between high and low collagen straightness groups, p = .0053. The lower straightness group had higher distant RFS rate than upper group. The results of multivariate Cox regression were consistent with the Kaplan-Meier curves. Compared to the high collagen width group, the low collagen width group had a 57% lower chance of dying, hazard ratio = 0.43, 95% CI [0.23, 0.78], p = .0056. The low collagen straightness group had a 60% lower chance of distant recurrence than the high collagen straightness group, hazard ratio = 0.40, 95% CI [0.19, 0.85], p =.0163. Conclusions: Quantitative collagen fiber metrics could help identify patients with resected pancreatic adenocarcinoma who are at risk of earlier death and distant recurrence.

Can the combination of citicoline and vitamin B12 be beneficial in the healing of corneal nerves after corneal cross-linking?

To evaluate the effect of topical citicoline, vitamin B12 and hyaluronic acid (OMK2 eye drops; Omikron Italia Srl, Italy) on the healing of corneal nerve after corneal cross-linking (CXL) treatment in patients with keratoconus (KC). A total of 44 eyes of 22 patients with KC who underwent CXL were included in this prospective study. After CXL, one eye of these patients received OMK2 eye dropandstandard post-CXL treatment (OMK2 group), while the fellow eye received onlystandard post-CXL treatment (control group). The following parameters were analyzed in the pre- and post-CXL procedure periods (1st, 3rd and 6th months): corneal sensitivity, tear film stability, central corneal thickness (CCT), and the corneal sub-basal nerve plexus (sbNP) parameters (including corneal nerve fiber density [CNFD], corneal nerve branch density [CNBD], corneal nerve fiber length [CNFL], corneal total branch density [CTBD], corneal nerve fiber area [CNFA], corneal nerve fiber width [CNFW]). Following CXL, a comparison of the baseline and month 6 data revealed that CNFA decreased in the control group (p < 0.001) and did not differ in the OMK2 group (p = 0.283). Other corneal sbNP parameters exhibited a decrease when comparing baseline and 6months in each group (all p < 0.05). In addition, CCT in the OMK2 group was not significantly different between baseline and month 6 (p = 0.052). However, a decline in CCT of the control groups was observed during this specified time interval (p = 0.009). Corneal sensitivity or tear film stability parameters did not differ significantly between groups at any time point or over time within each group (all p > 0.05). The use of OMK2 eye drop after CXL may provide more stable CNFA. In addition, it may also provide faster recovery in CCT.

PERFORMANCE ANALYSIS OF ADAPTIVE BIT LOADING SIPM-OOFDM IN INTENSITY MODULATION AND DIRECT DETECTION TDM- AND TWDM-PON SYSTEMS

Technological advancements over recent decades prompted the development of bandwidth-intensive services, necessitating the deployment of optical fibers in access networks up to the subscriber. To address these increasing demands, innovative transmission techniques, including advanced modulations and architectures, are expected. This study aimed to enhance transmission distance and user capacity in Passive Optical Networks (PON). The Subcarrier Index Power Modulated Optical Orthogonal Frequency Division Multiplexing (SIPM-OOFDM) technique, which conveyed additional information per subcarrier compared to conventional OOFDM, was implemented using MATLAB R2019a. To further improve the capacity performance, an Adaptive Bit Loading SIPM-OOFDM (ABL-SIPM-OOFDM) was implemented. We have modeled an IM/DD link in Optisystem7 and simulated the performance of conventional SIPM-OOFDM and ABL-SIPM-OOFDM in Time Division Multiplexing-PON (TDM-PON) and Time and Wavelength Division Multiplexing-PON (TWDM-PON) systems. The ABL-SIPM-OOFDM is shown to achieve an effective data rate of 18 Gb/s in TDM-PON, compared to 13 Gb/s with conventional SIPM-OOFDM, for a Bit Error Rate (BER) target of 10-3 at 20 km of fiber length with power budget supporting 64 users. This represents a 5 Gb/s increase in transmission capacity over the conventional approach.Additionally, in a TWDM-PON setup, the ABL-SIPM-OOFDM achieved an effective data rate of approximately 41 Gb/s over a distance of 40 km, supporting 64 Optical Network Units (ONU with 4 wavelengths each). In conclusion, the proposed ABL-SIPM-OOFDM demonstrated significant potential as a candidate for NG-PON systems, meeting the requirement of a 40 Gb/s downlink data rate for at least 256 users over a fiber distance of 40 km.

Neuropathic corneal pain following refractive surgery: risk factors, clinical manifestations, imaging and proteomic characteristics

Background/aimsTo identify the risk factors for neuropathic corneal pain (NCP) following corneal refractive surgery and to report its clinical manifestations, imaging and proteomic characteristics.MethodsThis 1 year prospective cohort study included...

An inserting pilot frequency-doubling millimeter wave radio over fiber system without bit walk-off effect by polarization modulator

Abstract An inserting pilot frequency-doubling millimeter-wave (MMW) radio over fiber (ROF) system is proposed to overcome fiber dispersion by polarization modulator (PoIM). At the central station, the optical carrier is first split into two beams, one beam is used as the pilot, and the other is modulated by a PolM with a composite radio frequency drive signal which is formed by combining the phase modulated data signal and the amplified data signal. By adjusting key parameters of the system, the output main components of the PolM are ±1st order sidebands, the downlink data signal is modulated only on the +1st order sideband. At the base station (BS), the pilot is reflected out by a fiber Bragg grating (FBG) and used as the optical carrier of uplink for carrier reuse. By feeding the output signal of the FBG into the photodetector, the frequency-doubling MMW signal with downlink is produced. In the case of BER is 10−9, and the length of fiber is 40 km and 80 km, the power penalty is 0.51 dB and 2.54 dB for the downlink, 0.49 dB and 4.72 dB for the uplink, respectively. Compared to the downlink of a conventional ROF system, in the 40 km and 80 km fiber transmission distance, our scheme raises the sensitivity of the receiver to 3.42 dB and 2.85 dB, respectively. Our designed ROF system can overcome the bit walk-off effect and have no problems with extinction ratio limitation and the DC drift. Carrier reuse realized by inserting a pilot can overcome the problems of downlink performance degradation and tunability restriction caused by conventional carrier reuse methods

Safety of Mechanically Fibrillated Cellulose Nanofibers (CNFs) by Inhalation Exposure Based on TG412

An investigation into the acute toxicity of mechanically fibrillated cellulose nanofibers (fib-CNFs), with a fiber length ranging from 500 to 600 nm, was conducted in accordance with the OECD TG412 guidelines. In this study, rats were exposed to fib-CNFs via nasal inhalation for 6 h daily over a 28-day period. The highest exposure concentration was set at 35 mg/m3, with intermediate and low concentrations at 7.0 mg/m3 and 1.5 mg/m3, respectively. No significant differences were observed in body weight, hematological parameters, or biochemical profiles between the fib-CNF-exposed groups and the control group. However, the histopathological examination of lung tissue revealed elevated macrophage counts in both the alveolar spaces and lymph nodes, accompanied by a significant increase in lung weight. The most severe effects were observed in the high-concentration group, while the low-concentration group exhibited only mild inflammatory changes. Based on these findings, the no observable adverse effect level (NOAEL) for the acute toxicity of fib-CNFs is estimated to be below 1.5 mg/m3.

Influence of screened fibre fractions on the properties of insulation panels made of different wood species

ABSTRACT The aim of this study was to produce wood fibre insulation panels (WFIP) from under-utilised wood species and to investigate how various fibre fractions and fibre dimensional distributions affect the hygricmechanical properties and thermal conductivity. Thermo-mechanical pulping (TMP) fibres from five wood species were separated into three fractions (unscreened, course, fine) using a tumbler screening machine. Rigid insulation panels with a target density of 110 kg m-3 were produced using 5 wt% polymeric diphenylmethane diisocyanate (pMDI) adhesive. Panels made from softwood fibres with a lower bulk density showed a different type of density profile compared to those made from hardwood fibres. The pattern of mean fibre length distribution density (q1) was similar for pine and larch as well as for beech and oak and was reflected in similar compression strength of the WFIP from the corresponding fractions. Water absorption was dependent on the wood species, irrespective of the fibre fraction. The hardwood panels (beech, oak) had a higher thermal conductivity (TC) than the softwood panels (spruce, pine, larch). The coarse fibre panels tended to have a higher TC than the fine fibre panels. Overall, the wood species and screening variants could be used to produce WFIP for indoor use.

МОРФОФУНКЦИОНАЛЬНЫЕ И БИОЭЛЕКТРИЧЕСКИЕ ХАРАКТЕРИСТИКИ НЕКОТОРЫХ МЫШЦ ЗАПЯСТНОГО СУСТАВА У СОБАКИ: ПИЛОТНОЕ ИССЛЕДОВАНИЕ

The paper presents the morphofunctional characteristics of some muscles of the dog's wrist joint, as well as their bioelectrical characteristics. The purpose of the study is to describe the bioelectrical characteristics of the radial and ulnar extensor carpi of the dog, taking into account the morphofunctional characteristics of these muscles. Objectives of the study: to conduct a morphological and electrophysiological study of the radial and ulnar extensor wrist muscles in dogs; identify patterns of EMG formation depending on the internal structure and innervation of muscles, and conduct a comparative assessment of the morphological and bioelectrical characteristics of the muscles being studied. Research was carried out at the Department of Anatomy, Histology, Physiology and Pathological Anatomy of the Omsk State Agrarian University named after P.A. Stolypin (Omsk). As a result of the studies, it was revealed that the innervation of the muscle fibers of the dog’s extensor carpi ulnaris and radialis has a similar, group character, that is, groups of muscle fibers have a large number of motor units. These groups are reflected on the EMG as separate complexes. An individual set of action potentials in the EMG signal pattern has duration of 0.01–0.014 s and a frequency of 600–800 Hz. The length of the muscle bundles inboth muscles is different: for the extensor carpi ulnaris it is 0.5 cm, for the radial one, respectively, 3.5 cm. Thus, it was found that the characteristics of the innervation and internal structure of the muscle affect the pattern of the EMG signal. The influence of muscle structure by the type of feathering and the length of muscle fibers (in feathery muscles) was not revealed. Thus, the resulting pattern (pattern) of the EMG signal is characteristic of statodynamic muscles. The proposed model of EMG signal formation, as a result of further development, will have the prospect of being used for qualitative and quantitative interpretation and assessment of the functional state of the neuromuscular system in animals and humans.

Improving fire resistance of lightweight concrete facade elements by using fibers

It is known that the most critical factor affecting fire resistance requirements in buildings is the building envelope, and therefore, improving the thermal properties of facade materials has become an important research area. In this context, studies examining the high temperature resistance properties of various facade materials have indicated that concrete has higher heat resistance compared to many facade materials. Lightweight concrete facade elements stand out for their structural durability and fire resistance at high temperatures. However, the different thermal expansion coefficients of aggregates and cement paste in concrete mixtures can lead to adverse outcomes under high temperatures, such as cracking or structural degradation. To mitigate these adverse effects, it has been suggested that adding fibers to lightweight concrete mixtures could enhance durability and improve fire resistance. This study investigated the effects of different fiber types, lengths, and usage rates on the high temperature resistance of lightweight concrete mixtures. In the experimental study, three different types of fibers—polypropylene, polyamide, and glass—were used in varying proportions of 0%, 0.25%, 0.5%, and 0.75% of the total volume. Polypropylene fibers were included at lengths of 3, 6, and 12 mm; polyamide fibers at 6 and 12 mm; and glass fibers at 13 and 25 mm. When observing the behavior of the mixtures under high temperatures, it was noted that mixtures with glass fibers performed best at 300 °C, while those with polypropylene fibers showed superior performance at 600 °C. This demonstrates the advantages of glass and polypropylene fibers in providing resilience at different temperature ranges. Furthermore, the optimal fiber usage rate for high temperature resistance was determined to be 0.25%. These findings highlight the importance of considering factors such as fiber type, length, and usage rate in the development of fire-resistant facade materials.

Trigger-Free and Low-Cross-Sensitivity Displacement Sensing System Using a Wavelength-Swept Laser and a Cascaded Balloon-like Interferometer

A wavelength-swept laser (WSL) demodulation system offers a unique time-domain analysis solution for high-sensitivity optical fiber sensors, providing a high-resolution and high-speed method compared to optical spectrum analysis. However, most traditional WSL-demodulated sensing systems require a synchronous trigger signal or an additional optical dispersion link for sensing analysis and typically use a fiber Bragg grating (FBG) as the sensing unit, which limits displacement sensitivity and increases fabrication costs. We present a novel displacement sensing system that combines a trigger-free WSL demodulation method with a cascaded balloon-like interferometer, featuring a simple structure, high sensitivity, and low temperature cross-sensitivity. The sensor is implemented by bending a short length of single-mode fiber with an optimal radius of around 4 mm to excite cladding modes, which form an interference spectral response with the core mode. Experimental findings reveal that the system achieves a high sensitivity of 397.6 pm/μm for displacement variation, corresponding to 19.88 ms/μm when demodulated using a WSL with a sweeping speed of 20 nm/s. At the same time, the temperature cross-sensitivity is as low as 5 pm/°C or 0.25 ms/°C, making it a strong candidate for displacement sensing in harsh environments with significant temperature interference.

Innovative porous panels made from alpine tree bark-fibre bundles for enhanced acoustic and thermal insulation

ABSTRACT To tackle climate change, raw material shortages and global competition, new technologies should better utilize existing resources. Tree bark, an abundant by-product from Alpine sawmills, offers a promising opportunity despite its heterogeneous nature. In this study, tree bark was homogenised into fibrous material and subsequently processed into novel binder free low-density and therefore porous fibreboards. The aim was to develop effective panels for acoustic and thermal insulation by varying the key parameters bark species, fibre size, density and its variations. The findings highlight the effectiveness of bark fibre-based panelss as thermal and acoustical insulators, achieving densities of 170–330 kg/m³, a noise-reduction coefficient (NRC) exceeding 0.5 for most specimenss, and thermal conductivity below 0.08 W/(m·K). Significant variations in fibre length, density, and tree species indicate the need for tailored manufacturing adjustments. Testing involved impedance tube methods for sound absorption and dynamic plane source tests for thermal properties. This study provides initial validation of this approach, underscoring its potential for future research in utilising tree bark effectively.

The effect of steel fibres on the uniaxial compressive strength and tensile strength of soil-cement

ABSTRACT Soil-cement is gaining acceptance in the construction industry for use in the improvement of sandy soil, despite its low strength Research has attempted to increase the strength of this material by increasing the percentage of additives. The current study investigated the effect of steel fibre (SF) as a reinforcer on the performance, UCS and TS at different fibre contents, lengths, diameters and shapes. The results showed that the use of 2% straight fibre significantly increased the UCS and that the samples performed better than those containing hooked or crimped. A decrease in the SF length from 10 to 5 mm and increase in the diameter from 0.3 to 0.6 mm caused decreases in the UCS. The greatest increase in TS occurred with the addition of 2% hooked fibres and was 4.6 times the increase in strength without fibres. The reason for the increase in the strength of the samples was bridge-like performance of the SFs in the soil-cement. The use of SFs together with cement to improve sandy soil is a new and effective way of improving the mechanical behaviour of the soil. This indicates that the addition of SFs can be a step towards more optimal use of soil-cement in engineering projects.

Wavelength Conversion Process of Intra-Pulse Stimulated Raman Scattering in Near-Zero Negative Dispersion Range

In the near-zero negative dispersion region of highly nonlinear fiber, the process of wavelength conversion based on the mechanism of intra-pulse stimulated Raman scattering is sensitive to the parameters of pumping pulse and fiber length under the combined effects of nonlinearity and dispersion. Therefore, we experimentally demonstrate the process in detail by using conventional soliton pulses with three sets of pulse parameters and two highly nonlinear fiber lengths of 400 m and 500 m. The experimental results show that, under the combined action of dispersion and several types of nonlinear mechanisms, the wavelength conversion processes are apparently different when using pulses with different parameters to pump different lengths of highly nonlinear fibers. Specifically, the separation degree of the frequency-shifted pulse spectrum and pumping pulse spectrum, and the corresponding redshift rate and pump power consumption all show significantly different results. The experimental results can guide the selection of more suitable parameters for the pumping pulse and the length of highly nonlinear fiber to achieve a better effect of wavelength redshift or spectrum broadening for various practical applications.