MyMedR

Displaying publications 1 - 20 of 90 in total

Abstract:

Sort:

5-Fluorouracil ethosomes - skin deposition and melanoma permeation synergism with microwave

Khan NR, Wong TW

Artif Cells Nanomed Biotechnol, 2018;46(sup1):568-577.
PMID: 29378453 DOI: 10.1080/21691401.2018.1431650

This study focuses on the use of ethosome and microwave technologies to facilitate skin penetration and/or deposition of 5-fluorouracil in vitro and in vivo. Low ethanol ethosomes were designed and processed by mechanical dispersion technique and had their size, zeta potential, morphology, drug content and encapsulation efficiency characterized. The skin was pre-treated with microwave at 2450 MHz for 2.5 min with ethosomes applied topically and subjected to in vitro and in vivo skin drug permeation as well as retention evaluation. The drug and/or ethosomes cytotoxicity, uptake and intracellular trafficking by SKMEL-28 melanoma cell culture were evaluated. Pre-treatment of skin by microwave promoted significant drug deposition in skin from ethosomes in vitro while keeping the level of drug permeation unaffected. Similar observations were obtained in vivo with reduced drug permeation into blood. Combination ethosome and microwave technologies enhanced intracellular localization of ethosomes through fluidization of cell membrane lipidic components as well as facilitating endocytosis by means of clathrin, macropinocytosis and in particularly lipid rafts pathways. The synergistic use of microwave and ethosomes opens a new horizon for skin malignant melanoma treatment.

Matched MeSH terms: Mechanical Phenomena
Modeling and Simulation of Two Wheelchair Accessories for Pushing Doors

Abdullah SJ, Shaikh Mohammed J

Assist Technol, 2018;30(4):165-175.
PMID: 28346064 DOI: 10.1080/10400435.2017.1293193

Independent mobility is vital to individuals of all ages, and wheelchairs have proven to be great personal mobility devices. The tasks of opening and navigating through a door are trivial for healthy people, while the same tasks could be difficult for some wheelchair users. A wide range of intelligent wheelchair controllers and systems, robotic arms, or manipulator attachments integrated with wheelchairs have been developed for various applications, including manipulating door knobs. Unfortunately, the intelligent wheelchairs and robotic attachments are not widely available as commercial products. Therefore, the current manuscript presents the modeling and simulation of a novel but simple technology in the form of a passive wheelchair accessory (straight, arm-like with a single wheel, and arc-shaped with multiple wheels) for pushing doors open from a wheelchair. From the simulations using different wheel shapes and sizes, it was found that the arc-shaped accessory could push open the doors faster and with almost half the required force as compared to the arm-like accessory. Also, smaller spherical wheels were found to be best in terms of reaction forces on the wheels. Prototypes based on the arc-shaped accessory design will be manufactured and evaluated for pushing doors open and dodging or gliding other obstacles.

Matched MeSH terms: Mechanical Phenomena
Fulltext Comparison of Orthodontic Bracket Debonding Force and Bracket Failure Pattern on Different Teeth In Vivo by a Prototype Debonding Device

Ahmed T, Rahman NA, Alam MK

Biomed Res Int, 2021;2021:6663683.
PMID: 33959664 DOI: 10.1155/2021/6663683

Objective: To compare the orthodontic bracket debonding force and assess the bracket failure pattern clinically between different teeth by a validated prototype debonding device. Materials and Method. Thirteen (13) patients at the end of comprehensive fixed orthodontic treatment, awaiting for bracket removal, were selected from the list. A total of 260 brackets from the central incisor to the second premolar in both jaws were debonded by a single clinician using a validated prototype debonding device equipped with a force sensitive resistor (FSR). Mean bracket debonding forces were specified to ten (10) groups of teeth. Following debonding, Intraoral microphotographs of the teeth were taken by the same clinician to assess the bracket failure pattern using a 4-point scale of adhesive remnant index (ARI). Statistical analysis included one-way ANOVA with post hoc Tukey HSD and independent sample t-test to compare in vivo bracket debonding force, Cohen's kappa (κ), and a nonparametric Kruskal-Wallis test for the reliability and the assessment of ARI scoring.
Results: A significant difference (p < 0.001) of mean debonding force was found between different types of teeth in vivo. Clinically, ARI scores were not significantly different (p = 0.921) between different groups, but overall higher scores were predominant.
Conclusion: Bracket debonding force should be measured on the same tooth from the same arch as the significant difference of mean debonding force exists between similar teeth of the upper and lower arches. The insignificant bracket failure pattern with higher ARI scores confirms less enamel damage irrespective of tooth types.

Matched MeSH terms: Mechanical Phenomena
Development of a control system for artificially rehabilitated limbs: a review

Bhuiyan MS, Choudhury IA, Dahari M

Biol Cybern, 2015 Apr;109(2):141-62.
PMID: 25491411 DOI: 10.1007/s00422-014-0635-1

Development of an advanced control system for prostheses (artificial limbs) is necessary to provide functionality, effectiveness, and preferably the feeling of a sound living limb. The development of the control system has introduced varieties of control strategies depending on the application. This paper reviews some control systems used for prosthetics, orthotics, and exoskeletons. The advantages and limitations of different control systems for particular applications have been discussed and presented in a comparative manner to help in deciding the appropriate method for pertinent application.

Matched MeSH terms: Mechanical Phenomena
Impacts of dynamic degradation on the morphological and mechanical characterisation of porous magnesium scaffold

Md Saad AP, Prakoso AT, Sulong MA, Basri H, Wahjuningrum DA, Syahrom A

Biomech Model Mechanobiol, 2019 Jun;18(3):797-811.
PMID: 30607641 DOI: 10.1007/s10237-018-01115-z

This study employs a computational approach to analyse the impact of morphological changes on the structural properties of biodegradable porous Mg subjected to a dynamic immersion test for its application as a bone scaffold. Porous Mg was immersed in a dynamic immersion test for 24, 48, and 72 h. Twelve specimens were prepared and scanned using micro-CT and then reconstructed into a 3D model for finite element analysis. The structural properties from the numerical simulation were then compared to the experimental values. Correlations between morphological parameters, structural properties, and fracture type were then made. The relative losses were observed to be in agreement with relative mass loss done experimentally. The degradation rates determined using exact (degraded) surface area at particular immersion times were on average 20% higher than the degradation rates obtained using original surface area. The dynamic degradation has significantly impacted the morphological changes of porous Mg in volume fraction, surface area, and trabecular separation, which in turn affects its structural properties and increases the immersion time.

Matched MeSH terms: Mechanical Phenomena*
Fulltext Assessment of muscle activity using electrical stimulation and mechanomyography: a systematic review

Uwamahoro R, Sundaraj K, Subramaniam ID

Biomed Eng Online, 2021 Jan 03;20(1):1.
PMID: 33390158 DOI: 10.1186/s12938-020-00840-w

This research has proved that mechanomyographic (MMG) signals can be used for evaluating muscle performance. Stimulation of the lost physiological functions of a muscle using an electrical signal has been determined crucial in clinical and experimental settings in which voluntary contraction fails in stimulating specific muscles. Previous studies have already indicated that characterizing contractile properties of muscles using MMG through neuromuscular electrical stimulation (NMES) showed excellent reliability. Thus, this review highlights the use of MMG signals on evaluating skeletal muscles under electrical stimulation. In total, 336 original articles were identified from the Scopus and SpringerLink electronic databases using search keywords for studies published between 2000 and 2020, and their eligibility for inclusion in this review has been screened using various inclusion criteria. After screening, 62 studies remained for analysis, with two additional articles from the bibliography, were categorized into the following: (1) fatigue, (2) torque, (3) force, (4) stiffness, (5) electrode development, (6) reliability of MMG and NMES approaches, and (7) validation of these techniques in clinical monitoring. This review has found that MMG through NMES provides feature factors for muscle activity assessment, highlighting standardized electromyostimulation and MMG parameters from different experimental protocols. Despite the evidence of mathematical computations in quantifying MMG along with NMES, the requirement of the processing speed, and fluctuation of MMG signals influence the technique to be prone to errors. Interestingly, although this review does not focus on machine learning, there are only few studies that have adopted it as an alternative to statistical analysis in the assessment of muscle fatigue, torque, and force. The results confirm the need for further investigation on the use of sophisticated computations of features of MMG signals from electrically stimulated muscles in muscle function assessment and assistive technology such as prosthetics control.

Matched MeSH terms: Mechanical Phenomena*
Frequency-controlled wireless shape memory polymer microactuator for drug delivery application

Zainal MA, Ahmad A, Mohamed Ali MS

Biomed Microdevices, 2017 Mar;19(1):8.
PMID: 28124762 DOI: 10.1007/s10544-017-0148-5

This paper reports the wireless Shape-Memory-Polymer actuator operated by external radio frequency magnetic fields and its application in a drug delivery device. The actuator is driven by a frequency-sensitive wireless resonant heater which is bonded directly to the Shape-Memory-Polymer and is activated only when the field frequency is tuned to the resonant frequency of heater. The heater is fabricated using a double-sided Cu-clad Polyimide with much simpler fabrication steps compared to previously reported methods. The actuation range of 140 μm as the tip opening distance is achieved at device temperature 44 °C in 30 s using 0.05 W RF power. A repeatability test shows that the actuator's average maximum displacement is 110 μm and standard deviation of 12 μm. An experiment is conducted to demonstrate drug release with 5 μL of an acidic solution loaded in the reservoir and the device is immersed in DI water. The actuator is successfully operated in water through wireless activation. The acidic solution is released and diffused in water with an average release rate of 0.172 μL/min.

Matched MeSH terms: Mechanical Phenomena*
Physicochemical characterization of kappa-carrageenan (Euchema cottoni) based films incorporated with various plant oils

R NFN, Nur Hanani ZA

Carbohydr Polym, 2017 Feb 10;157:1479-1487.
PMID: 27987859 DOI: 10.1016/j.carbpol.2016.11.026

This study investigated the effects of different types of plant oil (olive oil, corn oil, soybean oil and sunflower oil) on the physical and mechanical properties of kappa-carrageenan films from Euchema cottoni species. The incorporation of plant oils increased the film thickness significantly (P<0.05). However, the moisture content, solubility and tensile strength of films decreased significantly (P<0.05) as plant oils were added. The incorporation of plant oils also contributed to a plasticizing effect, whereby the values for elongation at break increased significantly (P<0.05), from 22.3% to 108.8%. Higher oil content also led to carrageenan films with lower opacity, which contradicted with previous studies. In conclusion, the plant oils used in this research significantly improved film properties, thus demonstrating the potential of these materials to be used as food packaging films and coatings.

Matched MeSH terms: Mechanical Phenomena
Mechanical compression controls the biosynthesis of human osteoarthritic chondrocytes in vitro

Chong PP, Panjavarnam P, Ahmad WNHW, Chan CK, Abbas AA, Merican AM, et al.

Clin Biomech (Bristol, Avon), 2020 10;79:105178.
PMID: 32988676 DOI: 10.1016/j.clinbiomech.2020.105178

BACKGROUND: Cartilage damage, which can potentially lead to osteoarthritis, is a leading cause of morbidity in the elderly population. Chondrocytes are sensitive to mechanical stimuli and their matrix-protein synthesis may be altered when chondrocytes experience a variety of in vivo loadings. Therefore, a study was conducted to evaluate the biosynthesis of isolated osteoarthritic chondrocytes which subjected to compression with varying dynamic compressive strains and loading durations.
METHODS: The proximal tibia was resected as a single osteochondral unit during total knee replacement from patients (N = 10). The osteoarthritic chondrocytes were isolated from the osteochondral units, and characterized using reverse transcriptase-polymerase chain reaction. The isolated osteoarthritic chondrocytes were cultured and embedded in agarose, and then subjected to 10% and 20% uniaxial dynamic compression up to 8-days using a bioreactor. The morphological features and changes in the osteoarthritic chondrocytes upon compression were evaluated using scanning electron microscopy. Safranin O was used to detect the presence of cartilage matrix proteoglycan expression while quantitative analysis was conducted by measuring type VI collagen using an immunohistochemistry and fluorescence intensity assay.
FINDINGS: Gene expression analysis indicated that the isolated osteoarthritic chondrocytes expressed chondrocyte-specific markers, including BGN, CD90 and HSPG-2. Moreover, the compressed osteoarthritic chondrocytes showed a more intense and broader deposition of proteoglycan and type VI collagen than control. The expression of type VI collagen was directly proportional to the duration of compression in which 8-days compression was significantly higher than 4-days compression. The 20% compression showed significantly higher intensity compared to 10% compression in 4- and 8-days.
INTERPRETATION: The biosynthetic activity of human chondrocytes from osteoarthritic joints can be enhanced using selected compression regimes.

Matched MeSH terms: Biomechanical Phenomena; Mechanical Phenomena*
The Safety and Strength of a Novel Medial, Partial Nonthreaded Pedicle Screw: A Cadaveric and Biomechanical Investigation

Kwan MK, Chan CY, Saw LB, Rukmanikanthan S, Lenke LG

Clin Spine Surg, 2017 04;30(3):E297-E304.
PMID: 28323715 DOI: 10.1097/BSD.0b013e3182aab29d

STUDY DESIGN: Cadaveric and biomechanical study.
OBJECTIVE: The aim of this study was to assess the safety and pullout strength of medial, partial nonthreaded thoracic pedicle screws compared with conventional screws.
SUMMARY OF BACKGROUND DATA: The perforation rate of the pedicle screws has been reported as high as 41%. Nerve injury and irritation can result from the compression of malpositioned screw on neural structures.
METHODS: Ten fresh cadavers were studied. Screws, 5.0 and 6.0 mm, were inserted from T1 to T6 and T7 to T12, respectively. Pedicle perforations and fractures were recorded upon screw insertion and final positioning (nonthreaded portion facing medially) after a wide laminectomy. Pullout strength of novel and conventional screws were then tested using an Instron machine in an artificial bone substitute.
RESULTS: A total of 240 thoracic pedicle screws were inserted. Of them, 88.8% (213 screws) were fully contained during screw insertion. There were 5.0% (12 screws) grade 1 medial perforations and 6.2% (15 screws) grade 1 lateral perforations during screw insertion. Upon final positioning, 93.8% (225 screws) were fully contained. All grade 1 medial perforations, which occurred during insertion, were converted to grade 0. No dural or nerve root injuries occurred. Pedicle split fractures were noted in 6.7% (16 screws). The use of medial, partial nonthreaded screws reduced the overall perforation rate from 11.2% to 6.2%. The mean pullout load for the 5 mm fully threaded screw versus medial, partial nonthreaded was 1419.3±106.1 N (1275.8-1538.8 N) and 1336.6±44.2 N (1293.0-1405.1 N) respectively, whereas 6 mm pullout load averaged 2126.0±134.8 N (1986.3-2338.3 N) and 2036.5±210.0 N (1818.4-2355.9 N). The difference was not statistically significant.
CONCLUSIONS: The use of medial, partial nonthreaded pedicle screws reduced the medial perforation rate from 5.0% to 0%; however, the pullout strength was not significantly reduced. The use of this novel screw can potentially reduce the incidence of nerve injury or irritation after medial pedicle perforations.

Matched MeSH terms: Biomechanical Phenomena*; Mechanical Phenomena
Fulltext Computational analysis of fluid flow past a bluff body at low Reynolds number in different apex angle

Jusoh, M.Z.M., Nur Ain, A.R, Muhammad Wafi Md Nor

ESTEEM Academic Journal, 2020;16(2):65-74.
MyJurnal

A computational fluid dynamic analysis (CFD) is presented in the study of low Reynolds number fluid flow moving past bluff bodies. The study is focusing on the understanding of the effects of the apex-angles orientation on the flow structure and related occurring force. The apex-angle both facing upstream and downstream were computationally investigated. The simulation results of the cylinder solid are compared with available experimental data to justify the results and the model used. Results obtained in the present work were Strouhal number, drag coefficient, and Fast Fourier Transform (FFT). The study had found that the value of the drag force is increasing directly proportional to the apex angle. In contrast, the value of Strouhal number inversely proportional to the increasing of the apex angle. This was due to the flow over a cylinder creating a vortex shedding in the wake region which influenced the flow separation of fluid. Through the changing on orientation of the apex angle, it was also found that the characteristic linear dimension of the geometry will also be changed, thus affecting the flow pattern.

Matched MeSH terms: Mechanical Phenomena
Transmission of vibration through glove materials: effects of contact force

Md Rezali KA, Griffin MJ

Ergonomics, 2018 Sep;61(9):1246-1258.
PMID: 29628001 DOI: 10.1080/00140139.2018.1462407

This study investigated effects of applied force on the apparent mass of the hand, the dynamic stiffness of glove materials and the transmission of vibration through gloves to the hand. For 10 subjects, 3 glove materials and 3 contact forces, apparent masses and glove transmissibilities were measured at the palm and at a finger at frequencies in the range 5-300 Hz. The dynamic stiffnesses of the materials were also measured. With increasing force, the dynamic stiffnesses of the materials increased, the apparent mass at the palm increased at frequencies greater than the resonance and the apparent mass at the finger increased at low frequencies. The effects of force on transmissibilities therefore differed between materials and depended on vibration frequency, but changes in apparent mass and dynamic stiffness had predictable effects on material transmissibility. Depending on the glove material, the transmission of vibration through a glove can be increased or decreased when increasing the applied force. Practitioner summary: Increasing the contact force (i.e. push force or grip force) can increase or decrease the transmission of vibration through a glove. The vibration transmissibilities of gloves should be assessed with a range of contact forces to understand their likely influence on the exposure of the hand and fingers to vibration.

Matched MeSH terms: Biomechanical Phenomena; Mechanical Phenomena
The use of salt-coating to improve textural, mechanical, cooking and sensory properties of air-dried yellow alkaline noodles

Yeoh SY, Lubowa M, Tan TC, Murad M, Mat Easa A

Food Chem, 2020 Dec 15;333:127425.
PMID: 32683254 DOI: 10.1016/j.foodchem.2020.127425

Zero-salted yellow alkaline noodles (YAN) were immersed in solutions of resistant starch HYLON™ VII (HC) or fruit coating Semperfresh™ (SC) containing a range of salt (NaCl) between 10 and 30% (w/v). The objective was to evaluate the effect of salt-coatings on the textural, handling, cooking, and sensory properties of YAN. Increasing salt in the coatings caused a reduction in optimum cooking time, cooking loss and increase in cooking yield. The mechanical and textural parameters, sensory hardness, springiness and overall sensory acceptability of the salt-coated noodles however decreased with increasing salt application. HC-Na10 and SC-Na10 showed the highest textural and mechanical parameters, sensory hardness and springiness. The differences in the parameters were attributed mainly to the water absorption properties of starch that was affected by salt application. Thus, the quality of salt-coated noodles was dependent mainly on the amounts of salt applied in the coatings rather than on the types of coatings used.

Matched MeSH terms: Mechanical Phenomena*
Fulltext Principal Component Analysis of the Running Ground Reaction Forces With Different Speeds

Yu L, Mei Q, Xiang L, Liu W, Mohamad NI, István B, et al.

Front Bioeng Biotechnol, 2021;9:629809.
PMID: 33842444 DOI: 10.3389/fbioe.2021.629809

Ground reaction force (GRF) is a key metric in biomechanical research, including parameters of loading rate (LR), first impact peak, second impact peak, and transient between first and second impact peaks in heel strike runners. The GRFs vary over time during stance. This study was aimed to investigate the variances of GRFs in rearfoot striking runners across incremental speeds. Thirty female and male runners joined the running tests on the instrumented treadmill with speeds of 2.7, 3.0, 3.3, and 3.7 m/s. The discrete parameters of vertical average loading rate in the current study are consistent with the literature findings. The principal component analysis was modeled to investigate the main variances (95%) in the GRFs over stance. The females varied in the magnitude of braking and propulsive forces (PC1, 84.93%), whereas the male runners varied in the timing of propulsion (PC1, 53.38%). The female runners dominantly varied in the transient between the first and second peaks of vertical GRF (PC1, 36.52%) and LR (PC2, 33.76%), whereas the males variated in the LR and second peak of vertical GRF (PC1, 78.69%). Knowledge reported in the current study suggested the difference of the magnitude and patterns of GRF between male and female runners across different speeds. These findings may have implications for the prevention of sex-specific running-related injuries and could be integrated with wearable signals for the in-field prediction and estimation of impact loadings and GRFs.

Matched MeSH terms: Biomechanical Phenomena; Mechanical Phenomena
Effect of cellulosic fiber scale on linear and non-linear mechanical performance of starch-based composites

Karimi S, Abdulkhani A, Tahir PM, Dufresne A

Int J Biol Macromol, 2016 Oct;91:1040-4.
PMID: 27339322 DOI: 10.1016/j.ijbiomac.2016.06.061

Cellulosic nanofibers (NFs) from kenaf bast were used to reinforce glycerol plasticized thermoplastic starch (TPS) matrices with varying contents (0-10wt%). The composites were prepared by casting/evaporation method. Raw fibers (RFs) reinforced TPS films were prepared with the same contents and conditions. The aim of study was to investigate the effects of filler dimension and loading on linear and non-linear mechanical performance of fabricated materials. Obtained results clearly demonstrated that the NF-reinforced composites had significantly greater mechanical performance than the RF-reinforced counterparts. This was attributed to the high aspect ratio and nano dimension of the reinforcing agents, as well as their compatibility with the TPS matrix, resulting in strong fiber/matrix interaction. Tensile strength and Young's modulus increased by 313% and 343%, respectively, with increasing NF content from 0 to 10wt%. Dynamic mechanical analysis (DMA) revealed an elevational trend in the glass transition temperature of amylopectin-rich domains in composites. The most eminent record was +18.5°C shift in temperature position of the film reinforced with 8% NF. This finding implied efficient dispersion of nanofibers in the matrix and their ability to form a network and restrict mobility of the system.

Matched MeSH terms: Mechanical Phenomena*
Evaluation of the thermomechanical properties and biodegradation of brown rice starch-based chitosan biodegradable composite films

Hasan M, Gopakumar DA, Olaiya NG, Zarlaida F, Alfian A, Aprinasari C, et al.

Int J Biol Macromol, 2020 Aug 01;156:896-905.
PMID: 32289410 DOI: 10.1016/j.ijbiomac.2020.04.039

Biodegradable films composed of starch and chitosan plasticized by palm oil were fabricated via a solvent casting technique. In this study, the influence of the ratio of brown rice starch and chitosan on the mechanical, thermal, antimicrobial, and morphological properties of the films was investigated. Antimicrobial films with a smooth surface and a compact structure of brown rice starch were obtained. The results showed that a higher proportion of chitosan in the polymer blends resulted in a substantial enhancement in the tensile strength (TS) and thermal stability of the film. The TS values for BRS100, BRS30CH70, BRS50CH50, BRS70CH30, and CH100 were 3.7, 15.2, 10.2, 9.3, and 8.8 MPa, respectively, and the elongation at break (EB) values of the BRS100, BRS30CH70, BRS50CH50, BRS70CH30, and CH100 samples were 39.5%, 34.7%, 7.3%, 11.5%, and 6.9%, respectively. The addition of chitosan to the brown rice starch samples resulted in a reduced water uptake of the film. The film with a balanced ratio of brown rice starch and chitosan exhibited excellent water resistance, with its water absorption being the lowest among all of the studied compositions.

Matched MeSH terms: Mechanical Phenomena*
Cross-linked chitosan/sepiolite composite for the adsorption of methylene blue and reactive orange 16

Marrakchi F, Khanday WA, Asif M, Hameed BH

Int J Biol Macromol, 2016 Dec;93(Pt A):1231-1239.
PMID: 27663552 DOI: 10.1016/j.ijbiomac.2016.09.069

Cross-linked chitosan/sepiolite composite was prepared from sepiolite clay and chitosan, and was cross-linked using epichlorohydrin. Among the various weight ratio percentage of chitosan and sepiolite clay composites, CS50SP50 was selected as the best adsorbent for both methylene blue (MB) and reactive orange 16 (RO 16). At an optimum adsorbent dosage of 0.2g/100mL, the effects of initial dye concentration (25-400mg/L) and pH (3-11) on MB and RO 16 adsorption onto CS50SP50 composite were studied. Monolayer adsorption capacities of CS50SP50 composite for MB and RO 16 were 40.986mg/g and 190.965mg/g, respectively at 30°C. Freundlich, Langmuir and Temkin isotherms applied on the adsorption data for both the dyes reveal that data fitted best for Freundlich model. For both the dyes pseudo-second-order kinetics were found to describe the adsorption process better than pseudo-first-order kinetics. The adsorption capacity of CS50SP50 composite for both the dyes was found better compared to previous studies thus making it potentially low-cost adsorbent for removal of both cationic and reactive dyes.

Matched MeSH terms: Mechanical Phenomena
Thermal and dynamic mechanical properties of cellulose nanofibers reinforced epoxy composites

Saba N, Safwan A, Sanyang ML, Mohammad F, Pervaiz M, Jawaid M, et al.

Int J Biol Macromol, 2017 Sep;102:822-828.
PMID: 28455253 DOI: 10.1016/j.ijbiomac.2017.04.074

The current study presents about the effect of cellulose nanofibers (CNFs) filler on the thermal and dynamic mechanical analysis (DMA) of epoxy composites as a function of temperature. In this study hand lay-up method was used to fabricate CNF reinforced Epoxy nanocomposites with CNF loading of 0.5%, 0.75%, and 1% into epoxy resin. The obtained thermal and DMA results illustrates that thermal stability, char content, storage modulus (E'), loss modulus (E") and glass transition temperature (Tg) increases for all CNF/epoxy nanocomposites compared to the pure epoxy. Thermal results revealed that 0.75% offers superior resistance or stability towards heat compared to its counterparts. In addition, 0.75% CNF/epoxy nanocomposites confers highest value of storage modulus as compared to 0.5% and 1% filler loading. Hence, it is concluded that 0.75% CNFs loading is the minimal to enhance both thermal and dynamic mechanical properties of the epoxy composites and can be utilized for advance material applications where thermal stability along with renewability are prime requirements.

Matched MeSH terms: Mechanical Phenomena*
Effects of plasticizers on the physicochemical properties of kappa-carrageenan films extracted from Eucheuma cottonii

Ili Balqis AM, Nor Khaizura MAR, Russly AR, Nur Hanani ZA

Int J Biol Macromol, 2017 Oct;103:721-732.
PMID: 28528954 DOI: 10.1016/j.ijbiomac.2017.05.105

The physicochemical properties of κ-carrageenan films extracted from Eucheuma cottonii (E. cottonii) incorporated with different concentrations and types of plasticizers were studied. Glycerol, sorbitol, and polyethylene glycol-300 (PEG-300) in the range of 10-60% were used as plasticizers. The results showed that the thickness and moisture content (MC) of films increased significantly (p≤0.05) with the increase in plasticizer concentration. Sorbitol-plasticized films had the lowest values. Sorbitol-plasticized films have better mechanical properties and the lowest water vapor permeability (WVP), solubility and water uptake ratio (WUR) compared with glycerol and PEG-plasticized films (p≤0.05). Fourier transform infrared (FTIR) spectra showed the intermolecular reactions between κ-carrageenan and the plasticizers in the films. Scanning electron microscopy (SEM) observations indicated that sorbitol-plasticized films have a compact structure, even at the highest concentration. The melting temperature (Tm) of films decreased (p≤0.05) with an increase in the plasticizer concentration. Here, the glycerol-plasticized films had the lowest values. X-ray diffraction (XRD) showed broad and narrow peaks of the un-plasticized κ-carrageenan film at 2θ=20.0° and 2θ=8.4°, respectively. The intensity of the broad peak increased and the narrow peak disappeared as the concentration of plasticizers increased. In conclusion, films from E. cottonii successfully produced with sorbitol as the plasticizer exhibited good physical properties as packaging films.

Matched MeSH terms: Mechanical Phenomena
Optimization, characterization, and in vitro assessment of alginate-pectin ionic cross-linked hydrogel film for wound dressing applications

Rezvanian M, Ahmad N, Mohd Amin MC, Ng SF

Int J Biol Macromol, 2017 Apr;97:131-140.
PMID: 28064048 DOI: 10.1016/j.ijbiomac.2016.12.079

Natural polymer-based hydrogel films have great potential for biomedical applications and are good candidates for wound dressings. In this study, we aimed to develop simvastatin-loaded crosslinked alginate-pectin hydrogel films by ionic crosslinking to improve the mechanical characteristics, wound fluid uptake and drug release behavior. Alginate-pectin hydrocolloid films were chemically crosslinked by immersing in different concentrations of CaCl2 (0.5-3% w/v) for 2-20min. The degree of crosslinking was influenced by both contact time and CaCl2 concentration. The optimized conditions for crosslinking were 0.5% and 1% (CaCl2) for 2min. The optimized hydrogel films were then characterized for their physical, mechanical, morphological, thermal, in vitro drug release, and cytocompatibility profiles. Crosslinking improved the mechanical profile and wound fluid uptake capacity of dressings. The hydrogel films were able to maintain their physical integrity during use, and the best results were obtained with the film in which the extent of crosslinking was low (0.5%). Thermal analysis confirmed that the crosslinking process enhanced the thermal stability of hydrogel films. Sustained, slow release of simvastatin was obtained from the crosslinked films and in vitro cytotoxicity assay demonstrated that the hydrogel films were non-toxic.

Matched MeSH terms: Mechanical Phenomena

Filters

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links