S-band Brillouin erbium fibre laser

A multi-wavelength Brillouin erbium fibre laser, which operates in short wavelength band (S-band), is proposed and demonstrated. The system employs both linear gain and nonlinear gain from a 20 m S-band erbium-doped fibre and a 500 m singlemode fibre, respectively, to generate an optical wavelength comb with spacing of approximately 0.084 nm. Two 80/20 couplers were used in the system as an internal feedback of generated Stokes signal to produce cascaded Brillouin Stokes for multiwavelength operation. A stable output laser comb of up to seven lines was obtained with a Brillouin pump of 3.5 mW and a 980 nm pump of 200 mW.     

Hydrothermal preparation of high saturation magnetization and coercivity cobalt ferrite nanocrystals without subsequent calcination

In this work, CoFe₂O₄ nanocrystals with high saturation magnetization (M_s) and high coercivity (H_c) have been fabricated via a simple hydrothermal method and without subsequent calcination. The resulting CoFe₂O₄ nanocrystals are characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectrometry, differential scanning calorimetry and vibrating sample magnetometry. The results indicate that CoFe₂O₄ nanocrystals are single crystal and the average crystallite size is increasing with the hydrothermal temperature. The electron micrographs show that the nanocrystals are well-dispersed and possess uniform size. The shape of CoFe₂O₄ nanocrystals is transformed from spherical into rod by increasing the hydrothermal temperature. The nanocrystals show relatively high M_s of 74.8 emu g⁻¹ and H_c of 2216 Oe, as compared to previous reported results. The obtained results reveal the applicability of this method for efficiently producing well crystallized and relatively high magnetic properties CoFe₂O₄ nanocrystals as compared to other methods. More importantly, it does not require further calcination processes.     

Adsorption of methylene blue onto hazelnut shell: Kinetics, mechanism and activation parameters

The adsorption kinetics of methylene blue (MB) on the hazelnut shell with respect to the initial dye concentration, pH, ionic strength, particle size and temperature were investigated. The rate and the transport/kinetic processes of MB adsorption were described by applying the first-order Lagergren, the pseudo-second-order, mass transfer coefficient and the intraparticle diffusion models. Kinetic studies showed that the kinetic data were well described by the pseudo-second-order kinetic model. Significant increases in initial adsorption rate were observed with the increase in temperature followed by pH and initial MB concentration. The intraparticle diffusion was found to be the rate-limiting step in the adsorption process. Adsorption activation energy was calculated to be 45.6kJmol(-1). The values of activation parameters such as free energy (DeltaG(*)), enthalpy (DeltaH(*)) and entropy (DeltaS(*)) were also determined as 83.4kJmol(-1), 42.9kJmol(-1) and -133.5Jmol(-1)K(-1), respectively.     

Analysis of SO2 sorption capacity of rice husk ash (RHA)/CaO/NaOH sorbents using response surface methodology (RSM): untreated and pretreated RHA

The SO2 sorption capacity (SSC) of sorbents prepared from rice husk ash (RHA) with NaOH as additive was studied in a fixed-bed reactor. The sorbents were prepared using a water hydration method by slurrying RHA, CaO, and NaOH. Response surface methodology (RSM) based on four-variable central composite face centered design (CCFCD) was employed in the synthesis of the sorbents. The correlation between the sorbent SSC (as response) with four independent sorbent preparation variables, i.e. hydration period, RHA/CaO ratio, NaOH amount, and drying temperature, were presented as empirical mathematical models. Among all the variables studied, the amount of NaOH used was found to be the most significant variable affecting the SSC of the sorbents prepared. The SSC for sorbent prepared with the addition of NaOH was found to be significantly higher than sorbents prepared without NaOH. This is probably because NaOH is a deliquescent material, and its existence increases the amount of water collected on the surface of the sorbent, a condition required for sorbent-SO2 reaction to occur at low temperature. The effect of further treatment of RHA at 600 degrees C was also investigated. Although pretreated RHA sorbents demonstrated higher SSC as compared to untreated RHA sorbents, nevertheless, at optimum conditions, sorbents prepared from untreated RHA was found to be more favorable due to practical and economic concerns.     

Measurement of neutron capture cross-section of the Ga(n, γ)Ga reaction at 0.0536 eV energy

The neutron capture cross-section for the ⁷¹Ga(n,  γ)⁷²Ga reaction at 0.0536 eV energy was measured using activation technique based on TRIGA Mark-II research reactor. The ¹⁹⁷Au(n, γ)¹⁹⁸Au monitor reaction was used to determine the effective neutron flux. Neutron absorption and γ-ray attenuation in gallium oxide pellet were corrected in determination of cross-section. The cross-section for the above reaction at 0.0536 eV amounts to 2.75 ± 0.14 b. As far as we know there are no experimental data available at our investigated energy. So far we are the first, who carried out experiment with 0.0536 eV neutrons for cross-section measurement. The present result is larger than that of JENDL-3.3, but consistent within the uncertainty range. The value of ENDF/B-VII is higher than this work. The result of this work will be useful to observe energy dependence of neutron capture cross-sections.     

Hydrogen production by Chlamydomonas reinhardtii in a two-stage process with and without illumination at alkaline pH

This work presents the results of a two-stage (carbon fixation and hydrogen production) experimental study for hydrogen production from microalgae using optical fiber as an internal light source. Effect of absence and presence of light on Chlamydomonas reinhardtii culture’s pH shift is also evaluated. The culture pH value is a function of light intensity; the pH in the alkaline range changes from 7.5 to 9.5 in the presence and absence of optical fiber respectively. The maximum rate of hydrogen production in the presence of exogenic glucose and optical fiber is 6 mL/L_cult/hour, which is higher than other reported values. This study has also revealed that the presence of light reduces the lag time for hydrogen production from 12 to 5 h.     

Success factors in developing iHeart as a patient-centric healthcare system: A multi-group analysis

Coronary Heart Disease is the number one killer disease not only in Malaysia and Iran but also in many countries around the world. Though early diagnosis is critical for successful treatment of the disease, immediate reaction in cases of emergency is crucial significance in saving the lives of stricken. Previous studies on patient-centric healthcare indicate that both the patient’s whereabouts and the locality of the healthcare centers play a vital role at moment of crisis. Not only it is important for a patient to be able to find the nearest healthcare points, it is also necessary for the emergency centers to know the exact location of the patient seeking for help. To this end, a Location-Based Mobile Cardiac Emergency System (iHeart) is proposed, which is a patient-centric healthcare system, to monitor and track the patient via a wearable device and their mobile phones. Therefore, this study aims to find healthcare professional’s opinion and to find success factors of such a system before its full implementation. A survey was conducted in the form of questionnaire in Malaysia and Iran. In order to conduct the survey, a conceptual model was proposed based on DeLone and McLean Information Success Model. A total number of 323 data was collected from both countries. The results were analyzed using Structural Equation Modeling (SEM) with AMOS software. Multi-group comparison was applied to find differences in points of view from both countries. The results of this study revealed the success factors of iHeart before the full implementation. It was found that nationality plays a moderating role between some of the success factors and success of iHeart. The success of a patient-centric healthcare system is bound to the culture of a particular nation as well as to the technological advancements, facilities, and the needs of the target users, meaning that in order for a novel healthcare system to be publicly acknowledged and utilized; target users must be classified and assessed accordingly. The findings of the present study are highly beneficial to both patients suffering from Coronary Heart Disease and the healthcare providers that seek to utilize new patient-centric healthcare systems, devices, and electronic applications to rescue patients.     

Assessment of the impact of coastal reclamation activities on seagrass meadows in Sungai Pulai estuary,Malaysia, using Landsat data (1994–2017)

Seagrass meadows play a critical role in supporting coastal biodiversity and in providing food and habitats for other marine organisms but are continuously threatened by human activities, such as coastal reclamation in the maritime countries. The Sungai Pulai estuary harbours mangroves, mudflats, and shoals with one of the Malaysia’s largest seagrass meadow (Merambong, Tanjung Adang, and Tanjung Laut) in Johor, Malaysia. This study assessed the environmental impact of coastal reclamation activities based on Landsat imagery (1994–2017) through mapping cover and distribution changes of those seagrass meadows by using a previously developed image enhancement technique with further improvement in the classification scheme (87% overall accuracy). The image-difference maps showed changes in seagrass meadows and mudflat cover with the extension of reclaimed land. Some seagrass meadows experienced large-scale changes, and coastal reclamation activities have been suggested as main factors responsible for habitat degradation, reduction in coverage, and total loss due to physical damage and excessive sedimentation. Sufficient protection of on-site construction materials is essential if coastal areas are to conserve seagrass meadows. This Landsat-based image classification approach should help the coastal manager to map seagrass meadows and to monitor the environmental impact of reclamation activities with a large spatio-temporal scale.     

Motile Piezoelectric Nanoeels for Targeted Drug Delivery

The field of small‐scale robotics is undergoing a paradigm shift toward the use of soft smart materials. The integration of soft smart components in micro‐ and nanorobotic platforms not only allows for more sophisticated locomotion mechanisms, but also more closely mimicks the functioning of biological systems. A soft hybrid nanorobot that mimics an electric eel, a knifefish with an elongated cylindrical body that is able to generate electricity during its motion, is presented here. These nanoeels consist of a flexible piezoelectric tail composed of a polyvinylidene fluoride–based copolymer, linked to a polypyrrole nanowire, which is decorated with nickel rings for magnetic actuation. Upon the application of rotating magnetic fields, the piezoelectric soft tail is deformed causing changes in its electric polarization. Capitalizing on this magnetically coupled piezoelectric effect, electrostatically enhanced on‐demand release of therapeutic cargo loaded on the surface of the piezoelectric tail is demonstrated. It is also shown that this approach allows for a pulsatile release of payloads. Interestingly, the driving magnetic parameters can be selected to provide the nanoeel with translational motion or to control the discharge kinetics of the drug.