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Transtibial prosthetic suspension: less pistoning versus easy donning and doffing

Gholizadeh H, Abu Osman NA, Eshraghi A, Ali S, Sævarsson SK, Wan Abas WA, et al.

J Rehabil Res Dev, 2012;49(9):1321-30.
PMID: 23408214

Poor suspension increases slippage of the residual limb inside the socket during ambulation. The main purpose of this article is to evaluate the pistoning at the prosthetic liner-socket interface during gait and assess patients' satisfaction with two different liners. Two prostheses with seal-in and locking liners were fabricated for each of the 10 subjects with transtibial amputation. The Vicon motion system was used to measure the pistoning during gait. The subjects were also asked to complete a Prosthesis Evaluation Questionnaire. The results revealed higher pistoning inside the socket during gait with the locking liner than with the seal-in liner (p < 0.05). The overall satisfaction with the locking liner was higher (p < 0.05) because of the relative ease with which the patients could don and doff the device. As such, pistoning may not be the main factor that determines patients' overall satisfaction with the prosthesis and other factors may also contribute to comfort and satisfaction with prostheses. The article also verifies the feasibility of the Vicon motion system for measuring pistoning during gait.

Matched MeSH terms: Stress, Mechanical
Fulltext Effect of Ni on the Suppression of Sn Whisker Formation in Sn-0.7Cu Solder Joint

Hashim AN, Salleh MAAM, Sandu AV, Ramli MM, Yee KC, Mohd Mokhtar NZ, et al.

Materials (Basel), 2021 Feb 05;14(4).
PMID: 33562471 DOI: 10.3390/ma14040738

The evolution of internal compressive stress from the intermetallic compound (IMC) Cu6Sn5 growth is commonly acknowledged as the key inducement initiating the nucleation and growth of tin (Sn) whisker. This study investigates the effect of Sn-0.7Cu-0.05Ni on the nucleation and growth of Sn whisker under continuous mechanical stress induced. The Sn-0.7Cu-0.05Ni solder joint has a noticeable effect of suppression by diminishing the susceptibility of nucleation and growth of Sn whisker. By using a synchrotron micro X-ray fluorescence (µ-XRF) spectroscopy, it was found that a small amount of Ni alters the microstructure of Cu6Sn5 to form a (Cu,Ni)6Sn5 intermetallic layer. The morphology structure of the (Cu,Ni)6Sn5 interfacial intermetallic layer and Sn whisker growth were investigated by scanning electron microscope (SEM) in secondary and backscattered electron imaging mode, which showed that there is a strong correlation between the formation of Sn whisker and the composition of solder alloy. The thickness of the (Cu,Ni)6Sn5 IMC interfacial layer was relatively thinner and more refined, with a continuous fine scallop-shaped IMC interfacial layer, and consequently enhanced a greater incubation period for the nucleation and growth of the Sn whisker. These verification outcomes proposes a scientifically foundation to mitigate Sn whisker growth in lead-free solder joint.

Matched MeSH terms: Stress, Mechanical
Fulltext Transient Behavior in Variable Geometry Industrial Gas Turbines: A Comprehensive Overview of Pertinent Modeling Techniques

Hashmi MB, Lemma TA, Ahsan S, Rahman S

Entropy (Basel), 2021 Feb 22;23(2).
PMID: 33671488 DOI: 10.3390/e23020250

Generally, industrial gas turbines (IGT) face transient behavior during start-up, load change, shutdown and variations in ambient conditions. These transient conditions shift engine thermal equilibrium from one steady state to another steady state. In turn, various aero-thermal and mechanical stresses are developed that are adverse for engine's reliability, availability, and overall health. The transient behavior needs to be accurately predicted since it is highly related to low cycle fatigue and early failures, especially in the hot regions of the gas turbine. In the present paper, several critical aspects related to transient behavior and its modeling are reviewed and studied from the point of view of identifying potential research gaps within the context of fault detection and diagnostics (FDD) under dynamic conditions. Among the considered topics are, (i) general transient regimes and pertinent model formulation techniques, (ii) control mechanism for part-load operation, (iii) developing a database of variable geometry inlet guide vanes (VIGVs) and variable bleed valves (VBVs) schedules along with selection framework, and (iv) data compilation of shaft's polar moment of inertia for different types of engine's configurations. This comprehensive literature document, considering all the aspects of transient behavior and its associated modeling techniques will serve as an anchor point for the future researchers, gas turbine operators and design engineers for effective prognostics, FDD and predictive condition monitoring for variable geometry IGT.

Matched MeSH terms: Stress, Mechanical
Fulltext Characterization and in vivo study of decellularized aortic scaffolds using closed sonication system

Hazwani A, Sha'Ban M, Azhim A

Organogenesis, 2019;15(4):120-136.
PMID: 31495272 DOI: 10.1080/15476278.2019.1656997

Extracellular matrix (ECM) based bioscaffolds prepared by decellularization has increasingly emerged in tissue engineering application because it has structural, biochemical, and biomechanical cues that have dramatic effects upon cell behaviors. Therefore, we developed a closed sonication decellularization system to prepare ideal bioscaffolds with minimal adverse effects on the ECM. The decellularization was achieved at 170 kHz of ultrasound frequency in 0.1% and 2% Sodium Dodecyl Sulphate (SDS) solution for 10 hours. The immersion treatment as control was performed to compare the decellularization efficiency with our system. Cell removal and ECM structure were determined by histological staining and biochemical assay. Biomechanical properties were investigated by the indentation testing to test the stiffness, a residual force and compression of bioscaffolds. Additionally, in vivo implantation was performed in rat to investigate host tissue response. Compared to native tissues, histological staining and biochemical assay confirm the absence of cellularity with preservation of ECM structure. Moreover, sonication treatment has not affected the stiffness [N/mm] and a residual force [N] of the aortic scaffolds except for compression [%] which 2% SDS significantly decreased compared to native tissues showing higher SDS has a detrimental effect on ECM structure. Finally, minimal inflammatory response was observed after 1 and 5 weeks of implantation. This study reported that the novelty of our developed closed sonication system to prepare ideal bioscaffolds for tissue engineering applications.

Matched MeSH terms: Stress, Mechanical
Fulltext Effect of postoperative corticosteroids on surgical outcome and aqueous autotaxin following combined cataract and microhook ab interno trabeculotomy

Honjo M, Yamagishi R, Igarashi N, Ku CY, Kurano M, Yatomi Y, et al.

Sci Rep, 2021 01 12;11(1):747.
PMID: 33436915 DOI: 10.1038/s41598-020-80736-w

To evaluate the effect of postoperative corticosteroids on surgical outcome and autotaxin (ATX) levels after microhook ab interno trabeculotomy combined with cataract surgery (μLOT-CS), prospective, consecutive non-randomized case series comparing outcomes of 30 eyes with primary open angle glaucoma was performed. The aqueous ATX, intraocular pressure (IOP) and glaucoma medications were monitored for 3 months postoperatively. An in-vivo mouse μLOT model was generated. In vitro, ATX and fibrotic changes induced by dexamethasone (Dex) treatment following scratch (S) in cultured human trabecular meshwork (hTM) cells were assessed by immunofluorescence, immunoenzymatic assay, and RT-qPCR. Postoperative ATX at 1 week and the number of antiglaucoma medications at 3 months were significantly lower in non-steroid group, and steroid use was the only variable significantly associated with postoperative medications at 3 months in multiregression analyses. In vitro, ATX activity was significantly upregulated in the Dex + S group, and αSMA was significantly upregulated in the Dex and Dex + S groups. Fibronectin and COL1A1 were significantly upregulated in the S group. μLOT-CS decreased IOP and medications in the overall cohort, and non-use of postoperative steroids resulted in a smaller number of postoperative medications. Limiting postoperative steroids in μLOT may minimize IOP elevation and postoperative fibrosis.

Matched MeSH terms: Stress, Mechanical
The use of Weibull statistics in mechanical testing of brittle dental materials

Ibrahim WM, McCabe JF

J Nihon Univ Sch Dent, 1993 Dec;35(4):225-9.
PMID: 8158281

The mean strength that has traditionally been taken as a measurement of the strength of a material does not reflect the true strength, and therefore it cannot be used as a design parameter. This explains why many brittle materials fail at unpredictable stress, either below or above the mean strength. By using Weibull statistics, the prediction and assessment of strength can be made more sensibly. The performance of a material can be predicted by considering a stress at a lower level of failure probability.

Matched MeSH terms: Stress, Mechanical
Fulltext Evaluation of Interfacial Fracture Toughness and Interfacial Shear Strength of Typha Spp. Fiber/Polymer Composite by Double Shear Test Method

Ikramullah, Rizal S, Nakai Y, Shiozawa D, Khalil HPSA, Huzni S, et al.

Materials (Basel), 2019 Jul 10;12(14).
PMID: 31295885 DOI: 10.3390/ma12142225

The aim of this paper is to evaluate the Mode II interfacial fracture toughness and interfacial shear strength of Typha spp. fiber/PLLA and Typha spp. fiber/epoxy composite by using a double shear stress method with 3 fibers model composite. The surface condition of the fiber and crack propagation at the interface between the fiber and the matrix are observed by scanning electron microscope (SEM). Alkali treatment on Typha spp. fiber can make the fiber surface coarser, thus increasing the value of interfacial fracture toughness and interfacial shear strength. Typha spp. fiber/epoxy has a higher interfacial fracture value than that of Typha spp. fiber/PLLA. Interfacial fracture toughness on Typha spp. fiber/PLLA and Typha spp. fiber/epoxy composite model specimens were influenced by the matrix length, fiber spacing, fiber diameter and bonding area. Furthermore, the interfacial fracture toughness and the interfacial fracture shear stress of the composite model increased with the increasing duration of the surface treatment.

Matched MeSH terms: Stress, Mechanical
Fulltext Mechanical and Morphological Properties of Bio-Phenolic/Epoxy Polymer Blends

Ismail AS, Jawaid M, Hamid NH, Yahaya R, Hassan A

Molecules, 2021 Feb 03;26(4).
PMID: 33546097 DOI: 10.3390/molecules26040773

Polymer blends is a well-established and suitable method to produced new polymeric materials as compared to synthesis of a new polymer. The combination of two different types of polymers will produce a new and unique material, which has the attribute of both polymers. The aim of this work is to analyze mechanical and morphological properties of bio-phenolic/epoxy polymer blends to find the best formulation for future study. Bio-phenolic/epoxy polymer blends were fabricated using the hand lay-up method at different loading of bio-phenolic (5 wt%, 10 wt%, 15 wt%, 20 wt%, and 25 wt%) in the epoxy matrix whereas neat bio-phenolic and epoxy samples were also fabricated for comparison. Results indicated that mechanical properties were improved for bio-phenolic/epoxy polymer blends compared to neat epoxy and phenolic. In addition, there is no sign of phase separation in polymer blends. The highest tensile, flexural, and impact strength was shown by P-20(biophenolic-20 wt% and Epoxy-80 wt%) whereas P-25 (biophenolic-25 wt% and Epoxy-75 wt%) has the highest tensile and flexural modulus. Based on the finding, it is concluded that P-20 shows better overall mechanical properties among the polymer blends. Based on this finding, the bio-phenolic/epoxy blend with 20 wt% will be used for further study on flax-reinforced bio-phenolic/epoxy polymer blends.

Matched MeSH terms: Stress, Mechanical*
Modulation of the mechanical responses of synovial fibroblasts by osteoarthritis-associated inflammatory stressors

Jamal J, Roebuck MM, Lee SY, Frostick SP, Abbas AA, Merican AM, et al.

Int J Biochem Cell Biol, 2020 09;126:105800.
PMID: 32673644 DOI: 10.1016/j.biocel.2020.105800

OBJECTIVES: To compare mechanobiological response of synovial fibroblasts (SFb) from OA patient cohorts under mechanical load and inflammatory stressors for better understanding of SFb homeostatic functions.
METHODS: Primary SFb isolated from knee synovium of OA obese (OA-ob:SFb), OA-pre-obese (OA-Pob:SFb), non-OA arthroscopic (scope:SFb), and non-OA arthroscopic with cartilage damage (scope-CD:SFb) were exposed to OA-conditioned media (OACM), derived from OA obese (OA-ob:CM), OA-pre-obese (OA-Pob:CM), and mechanical stretch at either 0 %, 6 % or 10 % for 24 h. Differences in the mRNA levels of genes involved in extracellular matrix production, inflammation and secretory activity were measured.
RESULTS: Despite the significant BMI differences between the OA-ob and OA-Pob groups, OA-Pob has more patients with underlying dyslipidaemia, and low-grade synovitis with higher levels of secreted proteins, CXCL8, COL4A1, CCL4, SPARC and FGF2 in OA-Pob:CM. All primary SFb exhibited anti-proliferative activity with both OA-CM. Mechanical stretch stimulated lubricin production in scope:SFb, higher TGFβ1 and COL1A1 expressions in scope-CD:SFb. OA-Pob:CM stimulated greater detrimental effects than the OA-ob:CM, with higher pro-inflammatory cytokines, IL1β, IL6, COX2 and proteases such as aggrecanases, ADAMTS4 and ADAMTS5, and lower ECM matrix, COL1A1 expressions in all SFb. OA-ob:SFb were unresponsive but expressed higher pro-inflammatory cytokines under OA-Pob:CM treatment.
CONCLUSION: Both mechanical and inflammatory stressors regulate SFb molecular functions with heterogeneity in responses that are dependent on their pathological tissue of origins. While mechanical stretch promotes a favorable effect with enhanced lubricin production in scope:SFb and TGFβ1 and COL1A1 in scope-CD:SFb, the presence of excessively high OA-associated inflammatory mediators in OA-Pob:CM, predominantly SPARC, CXCL8 and FGF2 drive all SFb regardless of pathology, towards greater pro-inflammatory activities.

Matched MeSH terms: Stress, Mechanical*
Interfacial Mechanical Strength Enhancement for High-Performance ZnS Thin-Film Anodes

Jiang H, Peng H, Guo H, Zeng Y, Li L, Zhang Y, et al.

ACS Appl Mater Interfaces, 2020 Nov 18;12(46):51344-51356.
PMID: 33146507 DOI: 10.1021/acsami.0c13139

Thin-film lithium-ion microbatteries with a high energy density and long lifespan are exceedingly desired for developing self-powered integrated micro-nano devices and systems. However, exploring high-performance thin-film anodes still remains a challenge. Herein, a double-layer-structure diamond-like carbon-ZnS (DLC-ZnS) thin-film anode fabricated by radio frequency magnetron sputtering exhibits high specific capacity and good cycling stability up to 1000 cycles, superior to the pure ZnS thin-film anode. To understand the mechanism, the bimodal amplitude modulated-frequency modulated atomic force microscopy was used to explore the mechanical properties of the thin films, and the DLC layer shows significantly higher Young's modulus than the ZnS thin film. The DLC interface with a high Young's modulus can effectively buffer the mechanical stress originating from the huge volume changes of the ZnS layer during lithiation/delithiation processes; therefore, the DLC interface maintains the higher mechanical integrity of the DLC-ZnS thin film and improves the utilization of ZnS. In addition, the electrochemical kinetics of the DLC-ZnS and ZnS thin films were also investigated by electrochemical methods. Electrochemical impedance spectroscopy tests indicate the obstacle of the DLC interface to Li+ ion diffusion in the initial charge/discharge processes; however, the DLC-ZnS thin film exhibits lower total resistance than the ZnS thin film afterward. In particular, galvanostatic intermittent titration technique tests were performed to find out the differences between the two thin films during the galvanostatical charge/discharge processes. The results demonstrate the obviously enhanced conversion reaction reversibility and decreased alloy reaction polarization of the DLC-ZnS thin film; therefore, it delivers higher reversible capacity.

Matched MeSH terms: Stress, Mechanical
Finite element analysis of idealised unit cell cancellous structure based on morphological indices of cancellous bone

Kadir MR, Syahrom A, Ochsner A

Med Biol Eng Comput, 2010 May;48(5):497-505.
PMID: 20224954 DOI: 10.1007/s11517-010-0593-2

Human bones can be categorised into one of two types--the compact cortical and the porous cancellous. Whilst the cortical is a solid structure macroscopically, the structure of cancellous bone is highly complex with plate-like and strut-like structures of various sizes and shapes depending on the anatomical site. Reconstructing the actual structure of cancellous bone for defect filling is highly unfeasible. However, the complex structure can be simplified into an idealised structure with similar properties. In this study, two idealised architectures were developed based on morphological indices of cancellous bone: the tetrakaidecahedral and the prismatic. The two architectures were further subdivided into two types of microstructure, the first consists of struts only and the second consists of a combination of plates and struts. The microstructures were transformed into finite element models and displacement boundary condition was applied to all four idealised cancellous models with periodic boundary conditions. Eight unit cells extracted from the actual cancellous bone obtained from micro-computed tomography were also analysed with the same boundary conditions. Young's modulus values were calculated and comparison was made between the idealised and real cancellous structures. Results showed that all models with a combination of plates and struts have higher rigidity compared to the one with struts only. Values of Young's modulus from eight unit cells of cancellous bone varied from 42 to 479 MPa with an average of 234 MPa. The prismatic architecture with plates and rods closely resemble the average stiffness of a unit cell of cancellous bone.

Matched MeSH terms: Stress, Mechanical
Fulltext Bending response of cross-ply laminated composite plates with diagonally perturbed localized interfacial degeneration

Kam CZ, Kueh AB

ScientificWorldJournal, 2013;2013:350890.
PMID: 24319360 DOI: 10.1155/2013/350890

A laminated composite plate element with an interface description is developed using the finite element approach to investigate the bending performance of two-layer cross-ply laminated composite plates in presence of a diagonally perturbed localized interfacial degeneration between laminae. The stiffness of the laminate is expressed through the assembly of the stiffnesses of lamina sub-elements and interface element, the latter of which is formulated adopting the well-defined virtually zero-thickness concept. To account for the extent of both shear and axial weak bonding, a degeneration ratio is introduced in the interface formulation. The model has the advantage of simulating a localized weak bonding at arbitrary locations, with various degeneration areas and intensities, under the influence of numerous boundary conditions since the interfacial description is expressed discretely. Numerical results show that the bending behavior of laminate is significantly affected by the aforementioned parameters, the greatest effect of which is experienced by those with a localized total interface degeneration, representing the case of local delamination.

Matched MeSH terms: Stress, Mechanical
Influence of stenosis on hemodynamic parameters in the realistic left coronary artery under hyperemic conditions

Kamangar S, Badruddin IA, Badarudin A, Nik-Ghazali N, Govindaraju K, Salman Ahmed NJ, et al.

Comput Methods Biomech Biomed Engin, 2017 Mar;20(4):365-372.
PMID: 27612619 DOI: 10.1080/10255842.2016.1233402

The current study investigates the hyperemic flow effects on heamodynamics parameters such as velocity, wall shear stress in 3D coronary artery models with and without stenosis. The hyperemic flow is used to evaluate the functional significance of stenosis in the current era. Patients CT scan data of having healthy and coronary artery disease was chosen for the reconstruction of 3D coronary artery models. The diseased 3D models of coronary artery shows a narrowing of >50% lumen area. Computational fluid dynamics was performed to simulate the hyperemic flow condition. The results showed that the recirculation zone was observed immediate to the stenosis and highest wall shear stress was observed across the stenosis. The decrease in pressure was found downstream to the stenosis as compared to the coronary artery without stenosis. Our analysis provides an insight into the distribution of wall shear stress and pressure drop, thus improving our understanding of hyperemic flow effect under both conditions.

Matched MeSH terms: Stress, Mechanical
Fulltext A review on strengthening steel beams using FRP under fatigue

Kamruzzaman M, Jumaat MZ, Sulong NH, Islam AB

ScientificWorldJournal, 2014;2014:702537.
PMID: 25243221 DOI: 10.1155/2014/702537

In recent decades, the application of fibre-reinforced polymer (FRP) composites for strengthening structural elements has become an efficient option to meet the increased cyclic loads or repair due to corrosion or fatigue cracking. Hence, the objective of this study is to explore the existing FRP reinforcing techniques to care for fatigue damaged structural steel elements. This study covers the surface treatment techniques, adhesive curing, and support conditions under cyclic loading including fatigue performance, crack propagation, and failure modes with finite element (FE) simulation of the steel bridge girders and structural elements. FRP strengthening composites delay initial cracking, reduce the crack growth rate, extend the fatigue life, and decrease the stiffness decay with residual deflection. Prestressed carbon fibre-reinforced polymer (CFRP) is the best strengthening option. End anchorage prevents debonding of the CRRP strips at the beam ends by reducing the local interfacial shear and peel stresses. Hybrid-joint, nanoadhesive, and carbon-flex can also be attractive for strengthening systems.

Matched MeSH terms: Stress, Mechanical*
Aerosol-based delivery of fibroblast cells for treatment of lung diseases

Kardia E, Yusoff NM, Zakaria Z, Yahaya B

J Aerosol Med Pulm Drug Deliv, 2014 Feb;27(1):30-4.
PMID: 23409833 DOI: 10.1089/jamp.2012.1020

Cell-based therapy has great potential to treat patients with lung diseases. The administration of cells into an injured lung is one method of repairing and replacing lost lung tissue. However, different types of delivery have been studied and compared, and none of the techniques resulted in engraftment of a high number of cells into the targeted organ. In this in vitro study, a novel method of cell delivery was introduced to investigate the possibility of delivering aerosolized skin-derived fibroblasts.

Matched MeSH terms: Stress, Mechanical
Bio-corrosion behavior and mechanical characteristics of magnesium-titania-hydroxyapatite nanocomposites coated by magnesium-oxide flakes and silicon for use as resorbable bone fixation material

Khalajabadi SZ, Abu ABH, Ahmad N, Yajid MAM, Hj Redzuan NB, Nasiri R, et al.

J Mech Behav Biomed Mater, 2018 Jan;77:360-374.
PMID: 28985616 DOI: 10.1016/j.jmbbm.2017.09.032

This study was aimed to improve of the corrosion resistance and mechanical properties of Mg/15TiO2/5HA nanocomposite by silicon and magnesium oxide coatings prepared using a powder metallurgy method. The phase evolution, chemical composition, microstructure and mechanical properties of uncoated and coated samples were characterized. Electrochemical and immersion tests used to investigate the in vitro corrosion behavior of the fabricated samples. The adhesion strength of ~36MPa for MgO and ~32MPa for Si/MgO coatings to substrate was measured by adhesion test. Fabrication a homogenous double layer coating with uniform thicknesses consisting micro-sized particles of Si as outer layer and flake-like particles of MgO as the inner layer on the surface of Mg/15TiO2/5HA nanocomposite caused the corrosion resistance and ductility increased whereas the ultimate compressive stress decreased. However, after immersion in SBF solution, Si/MgO-coated sample indicates the best mechanical properties compared to those of the uncoated and MgO-coated samples. The increase of cell viability percentage of the normal human osteoblast (NHOst) cells indicates the improvement in biocompatibility of Mg/15TiO2/5HA nanocomposite by Si/MgO coating.

Matched MeSH terms: Stress, Mechanical
Fulltext Effects of wall shear stress on unsteady MHD conjugate flow in a porous medium with ramped wall temperature

Khan A, Khan I, Ali F, Ulhaq S, Shafie S

PLoS One, 2014;9(3):e90280.
PMID: 24621775 DOI: 10.1371/journal.pone.0090280

This study investigates the effects of an arbitrary wall shear stress on unsteady magnetohydrodynamic (MHD) flow of a Newtonian fluid with conjugate effects of heat and mass transfer. The fluid is considered in a porous medium over a vertical plate with ramped temperature. The influence of thermal radiation in the energy equations is also considered. The coupled partial differential equations governing the flow are solved by using the Laplace transform technique. Exact solutions for velocity and temperature in case of both ramped and constant wall temperature as well as for concentration are obtained. It is found that velocity solutions are more general and can produce a huge number of exact solutions correlative to various fluid motions. Graphical results are provided for various embedded flow parameters and discussed in details.

Matched MeSH terms: Stress, Mechanical*
Fulltext A scientific report on heat transfer analysis in mixed convection flow of Maxwell fluid over an oscillating vertical plate

Khan I, Shah NA, Dennis LC

Sci Rep, 2017 03 15;7:40147.
PMID: 28294186 DOI: 10.1038/srep40147

This scientific report investigates the heat transfer analysis in mixed convection flow of Maxwell fluid over an oscillating vertical plate with constant wall temperature. The problem is modelled in terms of coupled partial differential equations with initial and boundary conditions. Some suitable non-dimensional variables are introduced in order to transform the governing problem into dimensionless form. The resulting problem is solved via Laplace transform method and exact solutions for velocity, shear stress and temperature are obtained. These solutions are greatly influenced with the variation of embedded parameters which include the Prandtl number and Grashof number for various times. In the absence of free convection, the corresponding solutions representing the mechanical part of velocity reduced to the well known solutions in the literature. The total velocity is presented as a sum of both cosine and sine velocities. The unsteady velocity in each case is arranged in the form of transient and post transient parts. It is found that the post transient parts are independent of time. The solutions corresponding to Newtonian fluids are recovered as a special case and comparison between Newtonian fluid and Maxwell fluid is shown graphically.

Matched MeSH terms: Stress, Mechanical
Arabinoxylan-co-AA/HAp/TiO2 nanocomposite scaffold a potential material for bone tissue engineering: An in vitro study

Khan MUA, Haider S, Shah SA, Razak SIA, Hassan SA, Kadir MRA, et al.

Int J Biol Macromol, 2020 May 15;151:584-594.
PMID: 32081758 DOI: 10.1016/j.ijbiomac.2020.02.142

Arabinoxylan (AX) is a natural biological macromolecule with several potential biomedical applications. In this research, AX, nano-hydroxyapatite (n-HAp) and titanium dioxide (TiO2) based polymeric nanocomposite scaffolds were fabricated by the freeze-drying method. The physicochemical characterizations of these polymeric nanocomposite scaffolds were performed for surface morphology, porosity, swelling, biodegradability, mechanical, and biological properties. The scaffolds exhibited good porosity and rough surface morphology, which were efficiently controlled by TiO2 concentrations. MC3T3-E1 cells were employed to conduct the biocompatibility of these scaffolds. Scaffolds showed unique biocompatibility in vitro and was favorable for cell attachment and growth. PNS3 proved more biocompatible, showed interconnected porosity and substantial mechanical strength compared to PNS1, PNS2 and PNS4. Furthermore, it has also showed more affinity to cells and cell growth. The results illustrated that the bioactive nanocomposite scaffold has the potential to find applications in the tissue engineering field.

Matched MeSH terms: Stress, Mechanical
Fulltext An experimental study on pile spacing effects under lateral loading in sand

Khari M, Kassim KA, Adnan A

ScientificWorldJournal, 2013;2013:734292.
PMID: 24453900 DOI: 10.1155/2013/734292

Grouped and single pile behavior differs owing to the impacts of the pile-to-pile interaction. Ultimate lateral resistance and lateral subgrade modulus within a pile group are known as the key parameters in the soil-pile interaction phenomenon. In this study, a series of experimental investigation was carried out on single and group pile subjected to monotonic lateral loadings. Experimental investigations were conducted on twelve model pile groups of configurations 1 × 2, 1 × 3, 2 × 2, 3 × 3, and 3 × 2 for embedded length-to-diameter ratio l/d = 32 into loose and dense sand, spacing from 3 to 6 pile diameter, in parallel and series arrangement. The tests were performed in dry sand from Johor Bahru, Malaysia. To reconstruct the sand samples, the new designed apparatus, Mobile Pluviator, was adopted. The ultimate lateral load is increased 53% in increasing of s/d from 3 to 6 owing to effects of sand relative density. An increasing of the number of piles in-group decreases the group efficiency owing to the increasing of overlapped stress zones and active wedges. A ratio of s/d more than 6d is large enough to eliminate the pile-to-pile interaction and the group effects. It may be more in the loose sand.

Matched MeSH terms: Stress, Mechanical

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