Width Control Research Articles

Double-Network Hydrogel 3D BioPrinting Biocompatible with Fibroblast Cells for Tissue Engineering Applications

The present study examines the formulation of a biocompatible hydrogel bioink for 3D bioprinting, integrating poly(ethylene glycol) diacrylate (PEGDA) and sodium alginate (SA) using a double-network approach. These materials were chosen for their synergistic qualities, with PEGDA contributing to mechanical integrity and SA ensuring biocompatibility. Fibroblast cells were included in the bioink and printed with a Reg4Life bioprinter employing micro-extrusion technology. The optimisation of printing parameters included needle size and flow velocities. This led to precise structure development and yielded results with a negligible deviation in printed angles and better control of line widths. The rheological characteristics of the bioink were evaluated, demonstrating appropriate viscosity and shear-thinning behaviour for efficient extrusion. The mechanical characterisation revealed an average compressive modulus of 0.38 MPa, suitable for tissue engineering applications. The printability of the bioink was further confirmed through the evaluations of morphology and diffusion rates, confirming structural integrity. Biocompatibility assessments demonstrated a high cell viability rate of 82.65% following 48 h of incubation, supporting the bioink’s suitability for facilitating cell survival. This study introduced a reliable technique for producing tissue-engineered scaffolds that exhibit outstanding mechanical characteristics and cell viability, highlighting the promise of PEGDA–SA hydrogels in bioprinting applications.

Experimental Study on the Bending Behavior of Precast Concrete Segmental Bridges with Continuous Rebars at Joints

Longitudinal ordinary rebars are discontinuous at the joints of precast concrete segmental bridges (PCSBs), which can open under tensile stresses induced by bending moments. This will lead to durability issues with the joints. To improve the bending properties of PCSBs, a novel joint type featuring continuous rebars was proposed in the present study. Three specimens were subjected to testing to examine the bending behavior of PCSBs using this new joint design compared to traditional joints. The crack propagation, structural deformation, joint opening width, strain in rebars, failure mode, stiffness, and flexural capacity were comprehensively investigated. The test results reveal that the continuous rebars effectively transferred bending normal stress between joints, ensuring full development of cracks in each beam segment. Effective control of joint opening width was also observed. Compared to traditional joints, the new joints exhibited a 29% to 33% increase in cracking load and a 32% increase in ultimate load. Failure in the continuous rebar joints was characterized by partial anchorage failure of the rebars along with localized concrete crushing in the top compression zone. Based on the test results, a computational method was proposed for calculating the cracking strength and flexural capacity of the new joints.

Wavy Graphene Nanoribbons Containing Periodic Eight-Membered Rings for Light-Emitting Electrochemical Cells.

Precision graphene nanoribbons (GNRs) offer distinctive physicochemical properties that are highly dependent on their geometric topologies, thereby holding great potential for applications in carbon-based optoelectronics and spintronics. While the edge structure and width control has been a popular strategy for engineering the optoelectronic properties of GNRs, non-hexagonal-ring-containing GNRs remain underexplored due to synthetic challenges, despite offering an equally high potential for tailored properties. Herein, we report the synthesis of a wavy GNR (wGNR) embedding periodic eight-membered rings into its carbon skeleton, which is achieved by the A2B2-type Diels-Alder polymerization between dibenzocyclooctadiyne (6) and dicyclopenta[e,l]pyrene-5,11-dione derivative (8), followed by a selective Scholl reaction of the obtained ladder-type polymer (LTP) precursor. The obtained wGNR, with a length of up to 30 nm, is thoroughly characterized by solid-state NMR, FT-IR, Raman, and UV-Vis spectroscopy with the support of DFT calculations. The non-planar geometry of wGNR efficiently prevents the inter-ribbon π-π aggregation, leading to photoluminescence in solution. Consequently, the wGNR can function as an emissive layer for organic light-emitting electrochemical cells (OLECs), offering a proof-of-concept exploration in implementing luminescent GNRs into optoelectronic devices. The fast-responding OLECs employing wGNR will pave the way for advancements in OLEC technology and other optoelectronic devices.

Cooperative effect of hybrid polyethylene-basalt fibers on crack width control and mechanical properties in ECC

Engineered cementitious composite (ECC) reinforced with polyethylene (PE) fiber has large crack width and high production cost, and these two shortcomings affect its application in practical projects. In this study, basalt fiber (BF) was hybrid with PE fiber to achieve cooperative effect, developing a PE/BF-hybrid fiber ECC (PE/BF-HyECC) with tighter crack width and more economic advantages. The impacts of different fiber content on the pore structure, mechanical, and cost performance of PE/BF-HyECC were investigated. The PE/BF-HyECC with positive cooperative effect of 1.5 vol.% PE and 1.0 vol.% BF had higher strength and tighter crack width compared to PE-ECC with 2.0 vol.% PE. Its cost performance ratio was 1.19 to 1.37 times that of PE-ECC with 2.0 vol.% PE. The better performance and higher cost performance of PE/BF-HyECC is expected to expand its practical application.

Mechanical properties and cracking strength estimation of high-strength engineered cementitious composites considering the fracture process zone

In the present study, the effect of flaws on the mechanical properties of high-strength engineered cementitious composites (HS-ECC) was investigated. Compressive tests, tensile tests, and electron microscope scanning microscopic tests were designed to explore the influence mechanism of flaws on mechanical properties. The results show that the compressive failure of HS-ECC was primarily characterized by a high density of vertical micro-cracks, and the specimen maintained exceptional structural integrity. All tested mix ratios demonstrated tensile strain hardening. Notably, the test groups with an 18 mm fiber length exhibited superior crack width control, with an average crack width of less than 30 μm. A new fiber bridging model was proposed, informed by microstructural analysis and crack opening displacement observations. A theoretical formula for the cracking strength of HS-ECC was developed based on the fracture process zone concept. The calculated initial crack strength closely matches the experimental values, with a discrepancy range of [0, 17 %]. This close agreement provides robust validation for the accuracy and reliability of the enhanced cracking strength calculation theory, thereby supporting its application in the design of ECC.

Research on Process Control of Laser-Based Direct Energy Deposition Based on Real-Time Monitoring of Molten Pool

In the process of laser-based direct energy deposition (DED-LB), the quality of the deposited layer will be affected by the process parameters and the external environment, and there are problems such as poor stability and low accuracy. A molten pool monitoring method based on coaxial vision is proposed. Firstly, the molten pool image is captured by a coaxial CCD camera, and the geometric features of the molten pool are accurately extracted by image processing techniques such as grayscale, median filtering noise reduction, and K-means clustering combined with threshold segmentation. The molten pool width is accurately extracted by the Canny operator combined with the minimum boundary rectangle method, and it is used as the feedback of weld pool control. The influence of process parameters on the molten pool was further analyzed. The results show that with an increase in laser power, the width and area of the molten pool increase monotonously, but exceeding the material limit will cause distortion. Increasing the scanning speed will reduce the size of the molten pool. By comparing the molten pool under constant power mode and width control mode, it is found that in width control mode, the melt pool width fluctuates less, and the machining accuracy is improved, validating the effectiveness of the real-time control system.

Temperature-Gradient Solution Deposition Amends Unfavorable Band Structure of Sb2(S,Se)3 Film for Highly Efficient Solar Cells.

Band structure of a semiconducting film critically determines the charge separation and transport efficiency. In antimony selenosulfide (Sb2(S,Se)3) solar cells, the hydrothermal method has achieved control of band gap width of Sb2(S,Se)3 thin film through tuning the atomic ratio of S/Se, resulting in an efficiency breakthrough towards 10 %. However, the obtained band structure exhibits an unfavorable gradient distribution in terms of carrier transport, which seriously impedes the device efficiency improvement. To solve this problem, here we develop a strategy by intentionally regulating hydrothermal temperature to control the chemical reaction kinetics between S and Se sources with Sb source. This approach enables the control over vertical distribution of S/Se atomic ratio in Sb2(S,Se)3 films, forming a favorable band structure which is conducive to carrier transport. Meanwhile, the adjusted element distribution not only ensures the uniformity of grain structure, but also increases the Se content of the films and suppress sulfur vacancy defects. Ultimately, the device delivers a high efficiency of 10.55 %, which is among the highest reported efficiency of Sb2(S,Se)3 solar cells. This study provides an effective strategy towards manipulating the element distribution in mixed-anion compound films prepared by solution-based method to optimize their optical and electrical properties.

Improved stability of open bite deformities: taking control of the transverse width using digital technology and robotic archwire bending

Many factors need to be considered when selecting the treatment protocol for the surgical correction of skeletal open bite deformities. In order to achieve stable long-term results, it is essential to explore the origin of the open bite, including any dysfunction of the temporomandibular joint or tongue and compromised nasal breathing, in addition to the skeletal deformity. Recurrence of a skeletal open bite is associated with relapse of the expanded transverse width. Three-dimensional virtual planning allows different treatment options to be explored and final decisions to be made together with the orthodontist who also designs the patient’s digital occlusion. This study presents a treatment protocol for predictable and stable widening of the maxillary transverse width over the long term, involving premolar extraction and rounding and shortening of the upper dental arch by advancing the molar segments. The stability of inter-canine, inter-premolar, and inter-molar distances, as well as overjet and overbite, were measured in 16 patients treated with this technique; measurements were obtained pre- and post-surgery, and the mean follow-up was 43 months. Orthodontic treatment was designed digitally and finished with robotically bent wires (SureSmile), which allowed exact planning of the overall treatment until debonding, thus making orthognathic surgery more predictable for the patient. The changes in transverse width were significant and stable over time.

In-plane gate induced transition asymmetry of spin-resolved Landau levels in InAs-based quantum wells

The crossover from quasi-two- to quasi-one-dimensional electron transport subject to transverse electric fields and perpendicular magnetic fields is studied in the diffusive to quasi-ballistic and zero-field to quantum Hall regime. In-plane gates and Hall-bars have been fabricated from an InGaAs/InAlAs/InAs quantum well hosting a 2DEG with a carrier density of about 6.8 × 1011 cm−2, a mobility of 1.8 × 105 cm2/Vs, and an effective mass of 0.042me after illumination. Magnetotransport measurements at temperatures down to 50 mK and fields up to 12 T yield a high effective Landé factor of g*=16, enabling the resolution of spin-split subbands at magnetic fields of 2.5 T. In the quantum Hall regime, electrostatic control of an effective constriction width enables steering of the reflection and transmission of edge channels, allowing a separation of fully spin-polarized edge channels at filling factors ν = 1 und ν = 2. A change in the orientation of a transverse in-plane electric field in the constriction shifts the transition between Zeeman-split quantum Hall plateaus by ΔB ≈ 0.1 T and is consistent with an effective magnetic field of Beff ≈ 0.13 T by spin-dependent backscattering, indicating a change in the spin-split density of states.

Tension-shear characteristics, cost and environmental impact of polyethylene fiber reinforced engineered cementitious composites: The role of fiber content

Engineered cementitious composites (ECC) tailored with fibers is famous for distinguished tensile ductility and tight crack width control capacity. The ECC material of the structural members may be in the state of tension-shear stress, e.g. ECC in the shear span of beams. Accordingly, this research focuses on the characteristics of ECC with diverse polyethylene (PE) fiber contents (0.5%, 1.0%, 1.5% and 2.0%) under tension-shear loading. The basic characteristics of PE-ECC subjected to uniaxial tension, uniaxial compression and pure shear were tested. The tension-shear behaviors of PE-ECC subjected to various loading angles were investigated by an elaborately designed test fixture. PE-ECC with the fiber content of over 1% exhibited obvious multiple-cracking phenomenon when subjected to tension-shear loading, and crack number decreased as loading angle continued to raise. The tension-shear strength for PE-ECC was enhanced by increasing fiber content. The failure criteria stemmed from the octahedral stress space (linear function) or stress invariant can be applied for depicting the failure laws of PE-ECC. Additionally, cost comparison and environmental impact evaluation indicated that fiber cost accounted for a significant higher proportion of the total cost (over 36%), while the proportion of fiber carbon footprint to the entire carbon footprint was low (less than 12%). This research will provide a useful assistance in understanding the tension-shear behaviors of PE-ECC and further facilitating its structural applications.

Structural behaviour of reinforced concrete beams with self-healing cover zone as lost formwork

This study investigates the structural behaviour and self-healing performance of hybrid reinforced concrete (RC) beams, enhanced with a 1.5-cm-thick self-healing cover composed of bacteria-embedded strain hardening cementitious composite (SHCC), for its potential in crack width control and crack healing. The research focuses on the performance under both flexural and shear loading, examining aspects such as load-bearing capacity, surface crack pattern, crack propagation between layers, and healing effectiveness. Results demonstrate the successful activation of the healing function, alongside improvements in structural performance. Under flexural loading, hybrid beams exhibited greater load-bearing capacity and significantly improved crack control ability. The maximum crack width of the hybrid beams exceeded 0.3 mm at 124.7 kN load, whereas in the control beam the largest crack exceeded 0.3 mm at only 59.8 kN load. Under shear loading, while the influence of the cover on structural capacity was minimal, it notably improved post-peak ductility and energy dissipation. Interface delamination was not observed in both cases. The results of the current study demonstrate the potential of delivering the self-healing mechanism precisely where it is most needed, which presents a scalable and economically viable strategy for integrating self-healing technology into standard construction practices.

Width undulation drives flow convergence routing in five flashy ephemeral river types across a dry summer subtropical region

AbstractDuring the last decade, meter‐resolution topo‐bathymetric digital elevation models (DEMs) have become increasingly utilized within fluvial geomorphology, but most meter‐scale geomorphic analyses are done on just one to a few rivers. While such analyses have contributed greatly to our collective understanding of river discharge‐topography interactions, which is applicable in both river restoration design and environmental flow regulation contexts, their generalizability across a range of river types remains largely unevaluated. This study assessed the dominance of a single hydro‐morphodynamic mechanism, flow convergence routing, in 35 ephemeral rivers divided among five river types in California's South Coast region by answering five questions. Geomorphic covariance structure (GCS) analysis was performed on longitudinal standardized width and standardized, detrended bed elevation spatial series from meter‐resolution DEMs. All river types had coherent, multi‐scalar structures of longitudinal fluvial topography, implicating a process‐morphology link. GCS metrics revealed that landform patterning was consistent with the requirements of the morphodynamic mechanism of flow convergence routing. Thus, that process was found to be a broadly relevant channel altering mechanism among sites, but its relationship with water stage differed between river types. Specifically, river types in unconfined valleys exhibited a strong bankfull width control over base flow bed undulations, with no obvious flood‐stage control over bankfull landform patterning. River types in partially confined valleys also exhibited strong bankfull width control over base flow bed undulations, but their bankfull landform patterns appear to have coalesced with coherent width and bed elevation undulations during flood flows. Finally, metrics for confined river types showed that it takes higher magnitude, less frequent floods to set their coherent width and bed elevation undulations, but even these channels do exhibit flow convergence routing when given enough discharge for sufficient duration.

Association between Red cells distribution width and glycemic control among people with type 2 diabetes.

Objective: To evaluate Red blood cell distribution width (RDW) in people with type 2 diabetes and its relationship with glycemic control. Study Design: Retrospective study. Setting: Baqai Institute of Diabetology and Endocrinology, Baqai Medical University. Demographic, Clinical and Biochemical Data were retrieved from hospital management system of BIDE. Period: September 2018 to April 2019. Material & Methods: Ethical approval was obtained from the Institutional Review Board of BIDE. Based on the HbA1c values, patients were divided into two groups, HbA1c < 7.0% and HbA1c ≥ 7.0%. RDW calculated from RBC histogram in Nihon Kohden fully automated analyzer. Results: RDW found 13.9±1.88 and 13.57±1.64 (p-value 0.018) in good and poorly controlled glycemic groups respectively. Poor glycemic group had higher levels of white cell count (9.58±4.34) and Triglycerides (170.12±129.13) (p-value <0.05), whereas controlled glycemic group demonstrated higher levels of BMI (29.03±6.01), MCV (84.36±7.81) and HDL (33.75±12.31). RDW was directly correlated with gender (p-value <0.0001) and duration of diabetes (p-value 0.01), and showed significant and inverse correlation with HbA1c. Age, blood pressure, duration of diabetes, serum LDL cholesterol, and the CBC values demonstrated no significant differences between the both groups. Conclusion: We found significant correlation between RDW and glycemic control.

Shear Strength and Crack Width Control of Concrete Beams with High-Strength Shear Reinforcement

Shear Strength and Crack Width Control of Concrete Beams with High-Strength Shear Reinforcement

Role of 1D edge in the elasticity and fracture of h-BN doped graphene nanoribbons

Recent achievement of BN-graphene alloy material has enabled the potential of bandgap tuning through both sub-10 nm width control and BN concentration variation. However, its mechanics, which is necessary for prediction of stability in functional applications, is not well studied. Here, molecular dynamics simulation is performed to conduct uniaxial tensile test for BN-doped graphene nanoribbons (BN-GNR) with varying widths and BN atom fractions. Efforts are made to study the constitutive relations for the edges and the whole BN-GNR and explore the fracture mechanisms of the hybrid nanoribbons. The substantial softening effect of the edges induced by wrinkling alters the impact of BN concentration on the stiffness in the sub-20 nm regime deviating from the linear behaviour observed in the bulk case. Fracture properties are unexpectedly independent of BN concentrations unlike in the bulk and the failure behaviour is rather decided by the graphene ribbon edge structure. Here the armchair edges serve as the source of crack nucleation at an early stage leading to weakened strength and reduced stretchability, whereas zigzag edges do not promote early crack nucleation and leads to the size dependence of fracture properties.

Compact dual‐band balanced bandpass filter with controllable passbands using coplanar waveguide spiral cross resonators

AbstractIn this article, a novel coplanar waveguide (CPW) spiral cross resonators (SCRs) is introduced for creating a dual‐band balanced bandpass filter (BPF) with adjustable passbands. The resonant properties of the SCRs in both the differential mode (DM) and common mode (CM) are scrutinized. Furthermore, DM bisection offers two distinct parameters for internal coupling adjustment, enabling independent passband width control. A novel grounding wire feeding arrangement matches the external Q factor of the dual DM passbands. An additional stepped‐impedance short‐circuited conducting stub between resonators prevents excessive coupling while obtaining moderate bandwidths. Inherent CM suppression can be attained by distinguishing CM resonant frequencies distinct from the DM frequencies. To validate the design, a dual‐band balanced BPF designed and fabricated to operate at 2.42 and 5.2 GHz exhibits closely matching measured results compared to the simulated ones.

Analyzing and examining the impact of various fiber types on the mechanical and functional characteristics of UHPC

In this research, we compared the performance and mechanical properties of (UHPC) produced with varying percentages of waste and recycled fibers, including polypropylene plastic (plastic sack fibers) (PP), polyethylene terephthalate (PET), date palm fibers (DP), Monterey pine tree fibers (MP), human hair (HH), and aluminum (from metal cans) (AF). This was done in relation to a control sample of UHPC (WC). The study investigated the effects of different percentages of these fibers (0, 0.5, 1, 1.5, and 2 percent by weight of cement) with a length of 3 cm in self-compacting concrete. We conducted tests on fresh concrete, including Slump Flow, J-Ring, V-Funnel, L-Box, and U-Box, as well as tests on hardened concrete, such as compressive strength, tensile strength, permeability, crack width control, thermal cracking, Schmidt hammer tests, and ultrasonic pulse velocity. The results indicated that increasing the percentage of fibers (PP, PET, DP, AF, MP, and HH) in UHPC enhances tensile strength, reduces permeability, and increases compressive strength. Additionally, under the influence of temperature, a decrease in both the depth and length of cracks was observed in the concrete slabs. Notably, the inclusion of 2% human hair fibers (HH) in UHPC resulted in superior tensile strength, reduced permeability, and minimized both the length and depth of cracks compared to other fiber types. Conversely, the addition of 2% aluminum fibers (AF) led to a reduction in tensile strength, an increase in permeability, and an increase in both the length and depth of cracks. This research demonstrated that, in terms of mechanical and functional properties, human hair fibers provided better results in UHPC across all tests conducted, significantly enhancing the longevity of the structure.

An Adaptive Crack Width Prediction for Flexural Steel Reinforced UHPC Beams

The crack pattern of steel reinforced ultrahigh performance concrete (UHPC) beam is usually characterized by many densely distributed fine cracks (i.e., multiple microcracks) along with localized macrocrack, and the crack width development rate along the beam height is smaller than that of normal concrete since steel fibers and steel reinforcement bars are supposed to be effective in controlling crack width propagation of the UHPC beam. However, an effective crack width prediction formula is still underdeveloped for steel reinforced UHPC beam. The present study aims to formulate a crack width prediction equation based on the equations in Chinese code GB50010 where the parameters can be regressed and calibrated. Ten UHPC beams with different steel fiber volumes and reinforcing ratios are experimentally tested to collect crack width and spacing data for comparison and validation purposes. Nonuniformity distribution coefficient of rebar strain and average crack spacing are calibrated by the test data. Also, rebar stress is calculated with considering residual tensile strength of UHPC based on a sectional analysis. The modified crack width equation is validated with the test results, showing the best prediction accuracy of 0.97 and standard deviation of 0.11 for the test beams in this study compared to those predicted by JTG 3362, CECS 38, MC and AFGC. This study is emphasizing crack width prediction and control in designing UHPC structures.

Stability of development and dynamics of vitamin C content in the leaves of the berry apple tree in the conditions of technogenic pollution of the city of Novoaltaysk

The article considers the stability of the development of the berry apple tree in different growing conditions in Novoaltaysk. The fluctuating asymmetry of apple leaves was evaluated by 5 morphological features. We revealed a significant increase in comparison with the control of the leaf width, the length of the second second-order vein from the base of the leaf, the distance between the bases of the first and second second-order veins and the distance between the ends of the first and second second-order veins in apple leaves growing along highways and near industrial enterprises. There are 3 zones that differ in the integral indicator of the stability of the development of leaves in apple trees: conditionally normal (control), with an average degree of disturbance and critical. A regular change in the vitamin C content in the leaves of apple trees in a row is described: control -> courtyards, parks, squares -> roads with medium traffic intensity -> roads with high traffic intensity -> industrial zone.

Flexural and cracking behavior of corroded RC continuous beams strengthened with energized C‐FRCM system

AbstractThis paper presents an experimental investigation into the flexural and cracking behavior of corroded reinforced concrete continuous beams with 11‐month wet–dry cycles strengthened by anodic polarized carbon‐fabric‐reinforced cementitious matrix (C‐FRCM) plates. The failure modes and flexural bearing capacities were discussed. The influences of the layer of carbon fabric mesh and complete carbon fiber‐reinforced polymer (CFRP) wrapping as end anchorage on the strengthening effectiveness were explored. The complete crack development patterns were captured by a digital image correlation system, and the results showed that the C‐FRCM system can provide satisfactory crack width control, as proved by the reduced crack spacing and the maximum crack width. The flexural capacities of the strengthened beams were effectively enhanced and the debonding failure can be eliminated through complete CFRP wrappings. Moreover, the design recommendations were proposed based on the estimation of the crack development as per related design guidelines.