This paper utilizes the background oriented schlieren (BOS) technique to measure the velocity field of a variable density round jet. The density field of the jet is computed based on the light deflection created during the passage of light through the understudy jet. The deflection vector estimation was carried out using phase-based optical flow algorithms. The density field is further exploited to extract the axial and radial velocity vectors with the aid of continuity and energy equations. The experiment is conducted at six different jet-exit temperature values. Additional turbulence parameters, such as velocity variance and power spectral density of the vector field, are also computed. Finally, the measured velocity parameters are compared with the hot wire anemometer measurements and their correlation is displayed.
Using irradiated doped-silica preforms from which fibres for thermoluminescence dosimetry applications can be fabricated we have carried out a range of luminescence studies, the TL yield of the fibre systems offering many advantages over conventional passive dosimetry types. In this paper we investigate such media, showing emission spectra for irradiated preforms and the TL response of glass beads following irradiation to an 241Am-Be neutron source located in a tank of water, the glass fibres and beads offering the advantage of being able to be placed directly into liquid. The outcomes from these and other lines of research are intended to inform development of doped silica radiation dosimeters of versatile utility, extending from environmental evaluations through to clinical and industrial applications.
Graphite ion chambers and semiconductor diode detectors have been used to make measurements in phantoms but these active devices represent a clear disadvantage when considered for in vivo dosimetry. In such circumstance, dosimeters with atomic number similar to human tissue are needed. Carbon nanotubes have properties that potentially meet the demand, requiring low voltage in active devices and an atomic number similar to adipose tissue. In this study, single-wall carbon nanotubes (SWCNTs) buckypaper has been used to measure the beta particle dose deposited from a strontium-90 source, the medium displaying thermoluminescence at potentially useful sensitivity. As an example, the samples show a clear response for a dose of 2Gy. This finding suggests that carbon nanotubes can be used as a passive dosimeter specifically for the high levels of radiation exposures used in radiation therapy. Furthermore, the finding points towards further potential applications such as for space radiation measurements, not least because the medium satisfies a demand for light but strong materials of minimal capacitance.
The sample size calculation for a prevalence only needs a simple formula. However, there are a number of practical issues in selecting values for the parameters required in the formula. Several practical issues are addressed and appropriate recommendations are given. The paper also suggests the application of a software calculator that checks the normal approximation assumption and incorporates finite population correction in the sample size calculation.
Nanomaterial-based sensors with high sensitivity, fast response and recovery time, large detection range, and high chemical stability are in immense demand for the detection of hazardous gas molecules. Graphene nanoribbons (GNRs) which have exceptional electrical, physical, and chemical properties can fulfil all of these requirements. The detection of gas molecules using gas sensors, particularly in medical diagnostics and safety applications, is receiving particularly high demand. GNRs exhibit remarkable changes in their electrical characteristics when exposed to different gases through molecular adsorption. In this paper, the adsorption effects of the target gas molecules (CO and NO) on the electrical properties of the armchair graphene nanoribbon (AGNR)-based sensor are analytically modelled. Thus, the energy dispersion relation of AGNR is developed considering the molecular adsorption effect using a tight binding (TB) method. The carrier velocity is calculated based on the density of states (DOS) and carrier concentration (n) to obtain I-V characteristics and to monitor its variation in the presence of the gas molecules. Furthermore, the I-V characteristics and energy band structure of the AGNR sensor are simulated using first principle calculations to investigate the gas adsorption effects on these properties. To ensure the accuracy of the proposed model, the I-V characteristics of the AGNR sensor that are simulated based both on the proposed model and first principles calculations are compared, and an acceptable agreement is achieved.
Good Clinical Practice (GCP) is an international ethical and scientific quality standard for the design, conduct, performance, monitoring, auditing, recording, analyses and reporting of clinical trials. It also serves to protect the rights, integrity and confidentiality of trial subjects. It is very important to understand the background of the formation of the ICH-GCP guidelines as this, in itself, explains the reasons and the need for doing so. In this paper, we address the historical background and the events that led up to the formation of these guidelines. Today, the ICH-GCP guidelines are used in clinical trials throughout the globe with the main aim of protecting and preserving human rights.
Many papers have been written on the synthesis of gold nanoparticles but very few included pictures of the process, and none of them used video to show the whole process of synthesis. This paper records the process of synthesis of gold nanoparticles using video clips. Every process from cleaning of glassware, an important step in the synthesis of metallic nanoparticles, to the dialysis process is shown. It also includes the preparation of aqua regia and the actual synthesis of gold nanoparticles. In some papers, the dialysis process was omitted, but in this paper, it is included to complete the whole process as it is being used for purification.
In the organosolv pulping of the oil palm fronds, the influence of the operational variables of the pulping reactor (viz. cooking temperature and time, ethanol and NaOH concentration) on the properties of the resulting pulp (yield and kappa number) and paper sheets (tensile index and tear index) was investigated using a wavelet neural network model. The experimental results with error less than 0.0965 (in terms of MSE) were produced, and were then compared with those obtained from the response surface methodology. Performance assessment indicated that the neural network model possessed superior predictive ability than the polynomial model, since a very close agreement between the experimental and the predicted values was obtained.
The protocol for the enzymatic deinking of laser printed waste papers on a laboratory scale using cellulase (C) and hemicellulase (H) of Aspergillus niger (Amano) was developed as an effective method for paper recycling. A maximum deinking efficiency of almost 73% by the enzyme combination of C:H was obtained using the deinking conditions of pulping consistency of 1.0% (w/v) with the pulping time of 1.0min, temperature of 50 degrees C, pH=3.5, agitation rate of 60rpm, pulp concentration of 4% (w/v), concentration of each enzyme of 2.5U/g air dried pulp and the enzyme ratio of 1:1. The deinking efficiency was further enhanced to 95% using the optimized flotation system consisting of pH=6.0, Tween 80 of concentration 0.5% (w/w), working air flow rate of 10.0L/min and temperature of 45 degrees C. The deinked papers were found to exhibit properties comparable to the commercial papers suggesting the effectiveness of the enzymatic process developed.
Caustic pulping of oil-palm frond-fiber strands was conducted following a central composite design using a two-level factorial plan involving three pulping variables (temperature: 160-180 degrees C, time: 1-2 h, alkali charge: 20-30% NaOH). Responses of pulp properties to the process variables were analyzed using a statistical software (DESIGN-EXPERT). The results indicated that frond-fiber strands could be pulped with ease to about 35-45% yield. Statistically, the reaction time was not a significant factor while the influences of the treatment temperature and caustic charge were in general significantly relative to the properties of the resultant pulps.
Algae biomass comprises variety of biochemicals components such as carbohydrates, lipids and protein, which make them a feasible feedstock for biofuel production. However, high production cost mainly due to algae cultivation remains the main challenge in commercializing algae biofuels. Hence, extraction of other high value-added bioproducts from algae biomass is necessary to enhance the economic feasibility of algae biofuel production. This paper is aims to deliberate the recent developments of conventional technologies for algae biofuels production, such as biochemical and chemical conversion pathways, and extraction of a variety of bioproducts from algae biomass for various potential applications. Besides, life cycle evaluation studies on microalgae biorefinery are presented, focusing on case studies for various cultivation techniques, culture medium, harvesting, and dewatering techniques along with biofuel and bioenergy production pathways. Overall, the algae biorefinery provides new opportunities for valorisation of algae biomass for multiple products synthesis.
Electrospun polyhydroxybutyrate (PHB) fibers were dip-coated by polymethyl methacrylate-co-methacrylic acid, poly(MMA-co-MAA), which was synthesized in different molar ratios of the monomers via free-radical polymerization. Fabricated platfrom was employed for immobilization of the dengue antibody and subsequent detection of dengue enveloped virus in enzyme-linked immunosorbent assay (ELISA). There is a major advantage for combination of electrospun fibers and copolymers. Fiber structre of electrospun PHB provides large specific surface area available for biomolecular interaction. In addition, polymer coated parts of the platform inherited the premanent presence of surface carboxyl (-COOH) groups from MAA segments of the copolymer which can be effectively used for covalent and physical protein immobilization. By tuning the concentration of MAA monomers in polymerization reaction the concentration of surface -COOH groups can be carefully controlled. Therefore two different techniques have been used for immobilization of the dengue antibody aimed for dengue detection: physical attachment of dengue antibodies to the surface and covalent immobilization of antibodies through carbodiimide chemistry. In that perspective, several different characterization techniques were employed to investigate the new polymeric fiber platform such as scanning electron microscopy (SEM), atomic force microscopy (AFM), water contact angle (WCA) measurement and UV-vis titration. Regardless of the immobilization techniques, substantially higher signal intensity was recorded from developed platform in comparison to the conventional ELISA assay.
Advanced diagnostic technologies, such as polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA), have been widely used in well-equipped laboratories. However, they are not affordable or accessible in resource-limited settings due to the lack of basic infrastructure and/or trained operators. Paper-based diagnostic technologies are affordable, user-friendly, rapid, robust, and scalable for manufacturing, thus holding great potential to deliver point-of-care (POC) diagnostics to resource-limited settings. In this review, we present the working principles and reaction mechanism of paper-based diagnostics, including dipstick assays, lateral flow assays (LFAs), and microfluidic paper-based analytical devices (μPADs), as well as the selection of substrates and fabrication methods. Further, we report the advances in improving detection sensitivity, quantification readout, procedure simplification and multi-functionalization of paper-based diagnostics, and discuss the disadvantages of paper-based diagnostics. We envision that miniaturized and integrated paper-based diagnostic devices with the sample-in-answer-out capability will meet the diverse requirements for diagnosis and treatment monitoring at the POC.
Nucleic acid testing (NAT), as a molecular diagnostic technique, including nucleic acid extraction, amplification and detection, plays a fundamental role in medical diagnosis for timely medical treatment. However, current NAT technologies require relatively high-end instrumentation, skilled personnel, and are time-consuming. These drawbacks mean conventional NAT becomes impractical in many resource-limited disease-endemic settings, leading to an urgent need to develop a fast and portable NAT diagnostic tool. Paper-based devices are typically robust, cost-effective and user-friendly, holding a great potential for NAT at the point of care. In view of the escalating demand for the low cost diagnostic devices, we highlight the beneficial use of paper as a platform for NAT, the current state of its development, and the existing challenges preventing its widespread use. We suggest a strategy involving integrating all three steps of NAT into one single paper-based sample-to-answer diagnostic device for rapid medical diagnostics in the near future.
The finite element method is gaining acceptance in predicting mechanical response of various loading configurations and material orientations for failure analysis of composite laminates. Both fabrication of laminate samples and experimental procedures are often expensive and time consuming, and hence impractical, especially during the initial design stage. Finite element analyses require minimal amounts of input data, and the resulting stress and strain distributions can be determined throughout each individual ply. Using ANSYSTM, a commercially available finite element package, failure loads were predicted by simulating a uniaxial tensile loading on HTS40/977-2 Carbon/Epoxy composite with [+/-4512s lamination scheme. Two built-in failure theories in ANSYSTM features, viz., Maximum Stress and Tsai-Wu were applied in the simulation. The stress-strain and load-extension curves for both actual testing and FEA were then compared and the results are in good agreement. This paper is intended for researchers who have used or are considering using ANSYSTM for the prediction of failure in composite materials.
The advancement in communication and Internet technology leads to mass of online data available on the Internet. People communicate to each other with application such as Facebook, Twitter, Short Message Service and e-forum. Entries or posts from these applications are known as microtexts. Normally a microtext is very short, very noisy and does not follow the correct structure of a sentence either in the English language or the Malay language. High occurrence of noisy texts decreases the accuracy value when microtexts are processed. This paper proposes a prototype of a system known as Sistem Penterjemahan Mesej Atas Talian (SPMAT). The objective of the system is to 'clean' noisy texts in microtexts that are created online by the Malaysian. 5000 Facebook messages, 5000 Twitter messages and 5000 e-forum messages were collected. From these sources, few lists such as common noisy texts list, common acronyms list artificial abbreviations list and Bi-gram index were created and used in the normalization processed. In addition, the system kept messages that it normalized and updated the corpus when instructed by the user. The methods used in SPMAT had been tested with 100 online messages. The result indicated that 80% of the noisy texts incorporated in these messages had been identified and cleaned correctly.
The study reports on the preparation of cellulose nanocrystals (CNCs) from wastepaper, as an environmental friendly approach of source material, which can be a high availability and low-cost precursor for cellulose nanomaterial processing. Alkali and bleaching treatments were employed for the extraction of cellulose particles followed by controlled-conditions of acid hydrolysis for the isolation of CNCs. Attenuated total reflectance Fourier Transform Infrared (ATR FTIR) spectroscopy was used to analyze the cellulose particles extracted while Transmission electron microscopy images confirmed the presence of CNCs. The diameters of CNCs are in the range of 3-10nm with a length of 100-300nm while a crystallinity index of 75.9% was determined from X-ray diffraction analysis. The synthesis of this high aspect ratio of CNCs paves the way toward alternative reuse of wastepaper in the production of CNCs.
The requirement for high quality pulps which are widely used in paper industries has increased the demand for pulp refining (beating) process. Pulp refining is a promising approach to improve the pulp quality by changing the fiber characteristics. The diversity of research on the effect of refining on fiber properties which is due to the different pulp sources, pulp consistency and refining equipment has interested us to provide a review on the studies over the last decade. In this article, the influence of pulp refining on structural properties i.e., fibrillations, fine formation, fiber length, fiber curl, crystallinity and distribution of surface chemical compositions is reviewed. The effect of pulp refining on electrokinetic properties of fiber e.g., surface and total charges of pulps is discussed. In addition, an overview of different refining theories, refiners as well as some tests for assessing the pulp refining is presented.
Nanofibrillated cellulose from biomass has recently gained attention owing to their biodegradable nature, low density, high mechanical properties, economic value and renewability. Although they still suffer from two major drawbacks. The first challenge is the exploration of raw materials and its application in nanocomposites production. Second one is high energy consumption regarding the mechanical fibrillation. However, pretreatments before mechanical isolation can overcome this problem. Hydrophilic nature of nano-size cellulose fibers restricts good dispersion of these materials in hydrophobic polymers and therefore, leads to lower mechanical properties. Surface modification before or after mechanical defibrillation could be a solution for this problem. Additionally, drying affects the size of nanofibers and its properties which needs to study further. This review focuses on recent developments in pretreatments, nanofibrillated cellulose production and its application in nanopaper applications, coating additives, security papers, food packaging, and surface modifications and also for first time its drying.