Electron Beam Irradiation to Recrosslink Devulcanized Sulfur Cured Rubber Blended Polypropylene

This study aims to investigate the effect electron beam (EB) irradiation on the polypropylene/devulcanized sulfur cured rubber (PP‐DVC) compound. The PP‐DVC compounds were compounded using twin‐screw extruder and then compression molded into required shapes before irradiation begins. The gel content of all irradiated PP‐DVC compounds gradually increased with higher irradiation dose indicated that the presence of DVC plays an important role in crosslinking enhancement. The mechanical properties of PP‐DVC compounds were observed marginally higher at low irradiation dosages (≤50 kGy). However, higher irradiation dosages up to 200 kGy cause adverse effect to the PP‐DVC compounds. In addition, the application of low irradiation dosage could enhance the dispersion of DVC particles at 20 phr composition in PP matrix. This also found that the scanning electron microscopy (SEM) observation where the DVC particles dispersed better in PP matrix compared to that of nonirradiated samples. Further increment in irradiation dosages up to 200 kGy reduced the crystallinity caused by chain scissoring process could rupture the crystalline structure in PP matrix. It was also found that the wavenumber of the C? H and CH₂ groups for irradiated samples reduced at high irradiation dosages due to the formation of carbonyl group. POLYM. ENG. SCI., 59:1017–1027, 2019. © 2019 Society of Plastics Engineers     

Microbial reduction of graphene oxide and its application in microbial fuel cells and biophotovoltaics

Despite more than a decade of study, there are still significant obstacles to overcome before graphene can be successfully produced on a large scale for commercial use. Chemical oxidation of graphite to produce graphene oxide (GO), followed by a subsequent reduction process to synthesize reduced graphene oxide (rGO), is considered the most practical method for mass production. Microorganisms, which are abundant in nature and inexpensive, are one of the potential green reductants for rGO synthesis. However, there is no recent review discussing the reported microbial reduction of GO in detail. To address this, we present a comprehensive review on the reduction of GO by a range of microorganisms and compared their efficacies and reaction conditions. Also, presented were the mechanisms by which microorganisms reduce GO. We also reviewed the recent advancements in using microbially reduced GO as the anode and cathode material in the microbial fuel cell (MFC) and algal biophotovoltaics (BPV), as well as the challenges and future directions in microbial fuel cell research.     

Fabrication and characterization of Ge-doped flat fibres

In this paper, we demonstrate fabrication and characterization of Ge-doped flat fibres. The Ge-doped flat fibre was fabricated from a 6 mol% Ge-doped preform. The flat fibre was successfully fabricated using dual stage drawing. Near field characterization was done and results show similar modal profile patterns as simulated using the software COMSOL. The results confirmed that with dual stage drawing and optimized drawing parameters, flat fibres with no defect holes can be fabricated.     

WDM-PON Architectures With a Single Shared Interferometric Filter for Carrier-Reuse Upstream Transmission

We propose two novel wavelength-division-multiplexed passive-optical-network (WDM-PON) architectures where subcarriers are employed to transmit downstream data and optical carriers are reused for upstream transmission. Architecture I is designed for the situation where two short distribution fibers are available between the remote node (RN) and each optical network unit (ONU), whereas Architecture II is devised for the case where there is only one distribution fiber between the RN and each ONU. Both architectures use only one interferometric filter located at the RN to simultaneously separate all downlink optical carriers and subcarriers, leading to a considerable cost reduction in the implementation of the WDM-PONs. Separated optical carriers are then reused and injected into reflective semiconductor optical amplifiers as the uplink light sources, which eliminates the necessity of specific wavelength sources at the ONUs. The downstream subcarrier signals are directly detected using baseband receivers. Two multichannel upstream and downstream transmission experiments are carried out at 1.25 Gb/s using the proposed schemes. The impact of optical carrier-to-subcarrier ratio of downlink signal, Rayleigh-backscattering noise, and wavelength mismatch between laser source and filter on system performance is also investigated.     

Multiple serial and parallel concatenated single parity-check codes

Single parity-check (SPC) codes are applied in both parallel and serial concatenated structures to produce high-performance coding schemes. The number of concatenations or stages, M, is increased to improve system performance at moderate-to-low bit-error rates without changing the overall code parameters (namely, code rate and code block length). Analytical bounds are presented to estimate the performance at high signal-to-noise ratios. The SPC concatenated codes are considered with binary phase-shift keying and with 16-quadrature amplitude modulation bit-interleaved coded modulation on the additive white Gaussian noise channel and the independent Rayleigh fading channel. Simulations show that the four-stage serial or parallel concatenated SPC codes can, respectively, outperform or perform as well as 16-state turbo codes. Furthermore, decoding complexity is approximately 9-10 times less complex than that of 16-state turbo codes. The convergence behavior of both serial and parallel concatenated SPC codes is also discussed.     

Priority nutritional concerns in Asia

The sustained economic growth and increasing economic stability in the Asian region over the last three decades have been accompanied by changing lifestyles leading to significant changes in the food and nutrition issues facing Asian countries. The chronic diseases associated with excessive consumption of nutrients, especially fat, are becoming increasingly apparent. At the same time, Asia has a disproportionate share of the malnutrition problem. Underweight and stunting remain significant problems in many Asian communities, and micronutrient deficiencies of iron, iodine, and vitamin A continue to afflict large population groups. Effective data collection and analysis are essential to formulate and implement intervention programs to address both sides of the changing nutrition scenario in Asia.     

Proceedings of the workshop on food-consumption surveys in developing countries: future challenges

The workshop "Food-consumption surveys in developing countries: Future challenges," held in Chiang Rai, Thailand, January 25--26, 2003, brought together 30 nutritionists and food safety experts from 10 Southeast Asian countries as well as from countries outside the region. It provided a forum for sharing information and experiences relating to food-consumption survey methodology. It enabled detailed discussions of the gathering of food-consumption data in developing countries for purposes of nutrition assessment, exposure assessment, and studies of diet-disease relationships. The workshop participants emphasized the need to obtain the support of policy and decision makers to establish a mechanism for conducting regular coordinated food-consumption surveys to meet these needs. The participants emphasized the importance of identifying all relevant stakeholders and involving them in the planning and conduct of these surveys. A number of technical issues related to food-con.sumption surveys were discussed, including food-intake methodologies. It was felt that surveys on individuals are preferred, and a combination of 24-hour recall and food-frequency questionnaire would most likely provide the required data. The workshop emphasized the need to develop, maintain, and update databases at the national and regional levels for nutrients and non-nutrients as well as contaminants and food additives. To ensure that surveys are conducted regularly and professionally, the importance of having qualified and trained personnel was emphasized. Several issues related to reports of food-consumption data were discussed, including timely reporting, effective dissemination, and appropriate usage. The participants unanimously recommended the organization of further technical meetings or workshops to follow up on recommended activities and enable continuing regional collaboration on food-consumption surveys.     

Approximation-based control of nonlinear MIMO time-delay systems

Approximation-based control is presented for a class of multi-input multi-output (MIMO) nonlinear systems in block-triangular form with unknown state delays. Neural networks (NNs) are utilized to approximate and compensate for unknown functions in the system dynamics, including the unknown bounds of the functions of delayed states. The use of a separation technique removes the need for any assumption on the function of delayed states, and allows the handling of multiple delays in each function of delayed states. By combining the use of Lyapunov-Krasovskii functionals and adaptive NN backstepping, the proposed control guarantees that all closed-loop signals remain bounded, while the outputs converge to a neighborhood of the desired trajectories. Simulation results demonstrate the effectiveness of the proposed scheme.