The effects of alkali treatment on the mechanical and morphological properties of Pennisetum purpureum/glass-reinforced epoxy hybrid composites

The effects of alkali treatment on the mechanical properties, void contents and morphological of Pennisetum purpureum/glass-reinforced epoxy hybrid composites were studied. The composites were produced using the vacuum infusion method. Pennisetum purpureum fibres were treated with 5 and 10% dilute sodium hydroxide (NaOH) solution for 6?h. The epoxy resin was mixed with either the treated or untreated Pennisetum purpureum/glass fibres to a ratio of 70:30 (by volume). Tensile and flexural tests were performed on the composites in accordance with ASTM D638 and ASTM D790, respectively. The hybrid composites that contained 5% NaOH-treated Pennisetum purpureum fibres exhibited the greatest tensile and flexural strengths with lower void contents. Field-emission scanning electron microscopy fractography supported the findings showing lesser voids and fibre pull-outs suggesting good interfacial bonding between the matrix and reinforcement. The reduced of the void contents is suspected due to the reduced hemicellulose content within the treated Pennisetum purpureum fibre.     

Nanofork for single cells adhesion measurement via ESEM-nanomanipulator system

In this paper, single cells adhesion force was measured using a nanofork. The nanofork was used to pick up a single cell on a line array substrate inside an environmental scanning electron microscope (ESEM). The line array substrate was used to provide small gaps between the single cells and the substrate. Therefore, the nanofork could be inserted through these gaps in order to successfully pick up a single cell. Adhesion force was measured during the cell pick-up process from the deflection of the cantilever beam. The nanofork was fabricated using focused ion beam (FIB) etching process while the line array substrate was fabricated using nanoimprinting technology. As to investigate the effect of contact area on the strength of the adhesion force, two sizes of gap distance of line array substrate were used, i.e., 1 μm and 2 μm. Results showed that cells attached on the 1 μm gap line array substrate required more force to be released as compared to the cells attached on the 1 μm gap line array substrate.     

Preparation and characterization of hyperthin-skinned and high performances asymmetric polyethersulfone membrane for gas separation

Defect-free high performance membranes for O₂/N₂ separation were prepared by coating the porous polyethersulphone (PES) membrane of hyperthin-skin layer with silicone rubber. The combined effects of fabrication parameters in dry/wet phase inversion process and of the casting dope rheology enabled improved of membrane performance in O₂ and N₂ separation, i.e. the optimum range was found to be from 149 to 447 s^{− 1} and 10 to 14 s, respectively, for the shear rate and the evaporation time to prepare the hyperthin-skinned asymmetric polyethersulfone membranes. The optimum polymer concentration was 32 wt.% , 61 wt.% and 7 wt.% for PES, 1-methyl-2-pyrrolidone and water respectively. The thinnest skin layer thickness was 538 ± 95.6 Å. Evaporation time and casting shear have been identified as the dominant fabrication parameters in controlling skin layer thickness and skin integrity.     

Assessing leaf scale measurement for nitrogen content of oil palm: performance of discriminant analysis and Support Vector Machine classifiers

Nitrogen (N) is a crucial element in sustaining oil palm production. However, assessing N status of tall perennial crops such as oil palm is complex and not as straightforward as assessing annual crops, due to complex N partitioning, age, and larger amounts of respiratory loads. Hence, the objectives of this study were to evaluate the potential of spectral measurements obtained from leaf scale and machine learning approaches as a rapid tool for quantifying oil palm N status. This study involved assessing the performance of discriminant analysis (DA) and Support Vector Machine (SVM) classifiers for discriminating spectral bands sensitive to N sufficiency levels and comparing the predictive accuracy of DA and SVM for classifying N status of immature and mature oil palms. The experiment was conducted on immature Tenera seedlings (13 months old) and mature Tenera palm stands (9 and 12 years old) that were arranged in Randomized Complete Block Design with treatments varied from 0 to 2 kg N. Generally, the discriminant function of both classifiers was age-dependent. A clear trade-off between the classifiers’ number of spectral bands and their accuracies was observed; the DA with a larger number of optimal spectral bands could discriminate N sufficiency levels of all maturity classes with higher accuracies compared to the SVM, yet the latter could produce reasonable accuracies with a lesser number of spectral bands. N status of all maturity classes could be classified satisfactorily with SVM (71–88%) via the satellite-simulated blue and green bands, signifying the possibility to develop spectral index or an N-sensitive sensor for oil palm.     

The effects of cell sizes, environmental conditions, and growth phases on the strength of individual W303 yeast cells inside ESEM

We performed in situ measurements of mechanical properties of individual W303 wild-type yeast cells by using an integrated environmental scanning electron microscope (ESEM)-nanomanipulator system. Compression experiments to penetrate the cell walls of single cells of different cell sizes (about 3-6 micro m diameter), environmental conditions (600 Pa and 3 mPa), and growth phases (early log, mid log, late log and saturation) were conducted. The compression experiments were performed inside ESEM, embedded with a 7 DOF nanomanipulator with a sharp pyramidal end effector and a cooling stage, i.e., a temperature controller. ESEM itself can control the chamber pressure. Data clearly show an increment in penetration force, i.e., 96 +/- 2, 124 +/- 10, 163 +/- 1, and 234 +/- 14 nN at 3, 4, 5, and 6 micro m cell diameters, respectively. Whereas, 20-fold increase in penetration forces was recorded at different environmental conditions for 5 micro m cell diameter, i.e., 163 +/- 1 nN and 2.95 +/- 0.23 mu N at 600 Pa (ESEM mode) and 3 mPa (HV mode), respectively. This was further confirmed from quantitative estimation of average cell rigidity through the Hertz model, i.e., ESEM mode (3.31 +/- 0.11 MPa) and HV mode (26.02 +/- 3.66 MPa) for 5 micro m cell diameter. Finally, the penetration forces at different cell growth phases also show the increment pattern from log (early, mid, and late) to saturation phases, i.e., 161 +/- 25, 216 +/- 15, 255 +/- 21, and 408 +/- 41 nN, respectively.     

Evaluation on the effects of wax inhibitor and optimization of operating parameters for wax deposition in Malaysian crude oil

The complex phenomenon of wax deposition subject to thermal gradient in crude oil is one of the biggest challenges in petroleum industry. In this comparative study, two inhibitors which were poly(ethylene-co-vinyl acetate) (EVA) and xylene were investigated in terms of rate of wax deposition in Malaysian crude oil using one-factor-at-a-time (OFAT) approach and cold finger methods. Stirring rate and cold finger temperature were optimized using response surface methodology (RSM) after being investigated using OFAT. It can be concluded that EVA had higher capability of reducing wax in two different conditions where the minimum point of wax reduction was found at 400 rpm with 63.5% paraffin inhibition efficiency (PIE) and 10°C with 64.7% of PIE. The amount of waxes collected for each parameter were 0.35 and 0.49 g, respectively. To minimize the wax deposit amount, RSM approach was applied using rotatable central composite design (CCD). The result shows that the amount of wax deposit decreased significantly with the increase of temperature and the stirring rate which were set at 400 rpm and 19°C, rescpectively. The amount of wax deposit was successfully reduced to the minimum value of 0.0095 g after the optimization.     

Perfluorinated Ionomer‐Modified Hole‐Injection Layers: Ultrahigh‐Workfunction but Nonohmic Contacts

Recently it has been reported that Nafion oligomers, i.e., 2‐(2‐sulfonatotetrafluoroethoxy)‐2‐trifluoromethyltrifluoroethoxyfunctionalized oligotetrafluoroethylenes, also called perfluorinated ionomers (PFIs), can be blended into poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDT:PSSH) films to increase their workfunctions beyond 5.2 eV. These PFI‐modified films are useful for energy‐level alignment studies, and have been proposed as hole‐injection layers (HILs). It is shown here however that these HILs do not provide sufficiently fast hole transfer into adjacent polymer semiconductor layers with ionization potentials deeper than ≈5.2 eV. X‐ray and ultraviolet photoemission spectroscopies reveal that these HILs exhibit a molecularly‐thin PFI overlayer that sets up a surface dipole that provides the ultrahigh workfunction. This dipolar layer persists even when the subsequent organic semiconductor layer is deposited, as evidenced by measurements of the diode built‐in potentials. As a consequence, the PFI‐modified HILs produce a higher contact resistance, and a lower equilibrium density of holes at the semiconductor contact than might have been expected from simple thermodynamic considerations of the reduction in hole‐injection barrier. Thus the use of insulating dipolar surface layers at the charge‐injection contact to tune its workfunction to match the relevant transport level of the semiconductor is of limited utility to achieve ohmic contact in these devices.     

Screening of factor influencing wax deposition using full factorial experimental design

The purpose of this work was to study the rate of wax deposition of Malaysian crude oil using full factorial design. Important parameters affecting wax deposition such as experimental duration, speed of rotation, cold finger temperature, and inhibitor concentration were investigated. The individual effects of variables and its interaction effects towards the dependent variables were studied. Wax deposit is the dependent variable. The results of the study showed that less wax deposit was obtained (0.75 g) with optimal conditions of initial poly(ethylene-co-vinyl acetate) concentration of 5000 ppm, 2 h duration without rotation speed, and 15°C cold finger temperature. These results demonstrate that cold finger temperature and experimental duration could be the main factors affecting wax deposit formation. The minimum amount of wax deposit obtained could reduce the chances of blocked pipelines; however, crude oil production increased. Nevertheless, Design Expert can be a valuable tool to quantify and detect the special relationships of two of more factors known as interactions regarding how they factors could affect a process, especially for screening purpose.     

A Review of Cell Adhesion Studies for Biomedical and Biological Applications

Cell adhesion is essential in cell communication and regulation, and is of fundamental importance in the development and maintenance of tissues. The mechanical interactions between a cell and its extracellular matrix (ECM) can influence and control cell behavior and function. The essential function of cell adhesion has created tremendous interests in developing methods for measuring and studying cell adhesion properties. The study of cell adhesion could be categorized into cell adhesion attachment and detachment events. The study of cell adhesion has been widely explored via both events for many important purposes in cellular biology, biomedical, and engineering fields. Cell adhesion attachment and detachment events could be further grouped into the cell population and single cell approach. Various techniques to measure cell adhesion have been applied to many fields of study in order to gain understanding of cell signaling pathways, biomaterial studies for implantable sensors, artificial bone and tooth replacement, the development of tissue-on-a-chip and organ-on-a-chip in tissue engineering, the effects of biochemical treatments and environmental stimuli to the cell adhesion, the potential of drug treatments, cancer metastasis study, and the determination of the adhesion properties of normal and cancerous cells. This review discussed the overview of the available methods to study cell adhesion through attachment and detachment events.     

Development and material properties of new hybrid medium density fibreboard from empty fruit bunch and rubberwood

In this research, new hybrid medium density fibreboard (MDF) was produced by using rubberwood (RW) and empty fruit bunch (EFB) based on oven-dried weight. There are two different ratios of hybrid MDF from rubberwood and EFB were produced which are EFB:RW, 20:80 and EFB:RW, 50:50 at 65% and 93% relative humidity (RH). The effect of storage time and relative humidity on the mechanical and physical properties of new hybrid MDF was studied. It was found that at 93% relative humidity, new hybrid MDF exhibited a highest effect on the mechanical and physical properties of panel after 10 weeks storage time. It observed that, hybrid MDF with ratio of EFB:RW, 20:80 exhibited the highest mechanical (flexure test and internal bonding) and physical properties [moisture content (MC), thickness swelling (TS), water absorption (WA)] as compared to hybrid MDF produced from EFB:RW, 50:50. Thus, the result showed that addition of higher amount of EFB fibres in hybrid MDF will decreased the composites properties. The property of composites decreases with increase of relative humidity and storage time. The result showed that, at 65% humidity new hybrid MDF exhibited lower effect on mechanical and physical properties of the panel.