bluuebunny/crossref_metadata_2025 huggingface dataset:
Tunable liquid crystal frequency selective surface with the compact unit cell, large tuning range, and the passband of flat-top and sharp roll-off
Authors: Lv Jian-Feng , Ding Chang , Zhu Zhongbo , Li Xiaojun , Meng Fan-Yi , Han Jian-Qiao , Jin Tao , Wu Qun
Published: May 2021

In this paper, a design method for tunable liquid crystal (LC)-based frequency selective surface (FSS) with the compact unit cell, large tuning range, and the passband of flat-top and sharp roll-off is proposed. A very compact LC-based bandpass FSS unit cell with the dimension of 0.077 λ × 0.077 λ is designed based on a pair of planar vortex-shaped metallic structure with two large parallel patches, between which the LC is sandwiched. Results show that the central frequency of the FSS is tuned from 11.56 to 12.58 GHz, and the tuning range reaches up to 8.5%. In order to obtain the transmission characteristics of flat-top and sharp roll-off, a double-layer structure is proposed and combined with the LC-based FSS design. Theoretical analyses are conducted to declare the working principle of the double-layer LC-based FSS. A prototype sample for the double-layer LC-based FSS is designed and fabricated. Results show that the double-layer LC-based FSS structure achieves frequency selective characteristics with a flat-top passband of about 450 MHz and sharp roll-off for arbitrary LC states with −15 dB rectangle coefficient of 2.44 for arbitrary LC states. Moreover, stable frequency responses of the double-layer LC-based FSS under various incident angles from 0° to 45° are obtained for arbitrary LC states.
Acoustic wave filtering strategy based on gradient acoustic metamaterials
Authors: Liao Guangxin , Luan Congcong , Wang Zhenwei , Liu Jiapeng , Yao Xinhua , Fu Jianzhong
Published: May 2021

Acoustic metamaterials possess fire-new capacities to manipulate the reflected, refracted and diffracted wave wavefronts effectively and flexibly through designing special artificial structures. In this paper, a transmission-type phase gradient metamaterials with high efficiency transmission and variations phase shift covering a full range of 2π was reported. Capacities of manipulating transmission angle using the designed acoustic metamaterials were expected to be realized under the guidance of the generalized Snell’s law. An acoustic filtering strategy occupying the selective permeability for the desired transmitted frequency were theoretically and numerically presented. Furthermore, a multi-channel filtering strategy was also designed and demonstrated. The results verified that the devices were highly sensitive to the incidence frequency and the transmission coefficients over 0.7 can be obtained at the working frequencies. The provided devices show an overwhelming promise of applications in various situations, such as architectural acoustics, acoustic logical manipulation, noise control, ultrasound imaging and multifunctional materials.
A novel fuel cell design for operando energy-dispersive x-ray absorption measurements
Authors: Leach A S , Hack J , Amboage M , Diaz-Moreno S , Huang H , Cullen P L , Wilding M , Magliocca E , Miller T S , Howard C A , Brett D J L , Shearing P R , McMillan P F , Russell A E , Jervis R
Published: May 2021

A polymer electrolyte fuel cell has been designed to allow operando x-ray absorption spectroscopy (XAS) measurements of catalysts. The cell has been developed to operate under standard fuel cell conditions, with elevated temperatures and humidification of the gas-phase reactants, both of which greatly impact the catalyst utilisation. X-ray windows in the endplates of the cell facilitate collection of XAS spectra during fuel cell operation while maintaining good compression in the area of measurement. Results of polarisation curves and cyclic voltammograms showed that the operando cell performs well as a fuel cell, while also providing XAS data of suitable quality for robust XANES analysis. The cell has produced comparable XAS results when performing a cyclic voltammogram to an established in situ cell when measuring the Pt LIII edge. Similar trends of Pt oxidation, and reduction of the formed Pt oxide, have been presented with a time resolution of 5 s for each spectrum, paving the way for time-resolved spectral measurements of fuel cell catalysts in a fully-operating fuel cell.
Continuous approximation of the ZARC element with passive components
Authors: Heil Thomas , Jossen Andreas
Published: May 2021

The ZARC element is a parallel connection between a constant phase element and an ohmic resistor which describes the charge transfer and the double-layer capacitance at an electrode–electrolyte interface. However, this mathematical object has been determined using measurement data and cannot be derived from physical or chemical processes. In order to understand the dynamics of ZARC and its parameters’ influence in frequency and in time domain, we approximate it using fundamental equivalent circuits. Here, we introduce two approaches using RC circuits whose behaviours are well-known. The first method consists of infinitely many serially connected RC circuits which can be uniquely related to ZARC by explicit equations. In contrast, the second uses just three serially connected RC circuits, but adds a minimization problem. Both approaches depend only on three parameters: an ohmic resistance, a capacitance, and a newly defined parameter which is a measure of the modification of the single capacitances. Moreover, we show a decrease of the total capacitance of both impedances for growing deviations from the behavior of an RC circuit. Finally, since the properties of RC circuits are well known in frequency and in time domain, we deduce the behaviours of both methods in the time domain.
Spray measurements with the time-shift technique
Authors: Schaefer Walter , Tropea Cameron , Wigger Georg , Eierhoff Dirk
Published: May 2021

The time-shift technique is a well-documented technique for the size and velocity measurement of individual drops passing through one or two tightly focused laser beams. It is a counting technique, nominally applicable for pure liquid drops, but with potential to also characterize drops with embedded particles or drops containing a second dispersed phase. In the present study a novel approach to signal processing is introduced in which the signal detection and validation phase is eliminated. This extends the capabilities of the time-shift technique in two manners. For one, size and velocity estimates are made possible for drops exhibiting very poor signal structure or signal-to-noise ratio. Such signals are commonly expected when measuring complex drops, either drops with embedded nano/micro-particles (dispersions) or emulsions. Second, the size and velocity distributions are estimated not by processing of signals from individual drops (single realization counting technique), but from a large ensemble of drop signals, improving both computational speed and reducing the influence of outliers in final statistics. These capabilities are achieved without sacrificing accuracy of mean and variance estimates of size and velocity of drop ensembles. To demonstrate the advantages of this new approach, measurements of a paint spray are presented, processed using both standard processing routines and the new approach. Limitations concerning the application of this new approach are discussed in detail.
Measurements of fundamental frequency shifts in the air cavity mode of a violin originating from changes in molecular weight and temperature
Authors: Matsutani Akihiro
Published: May 2021

In the violin, the fundamental air cavity mode (the A0 mode) is associated with the sound radiated by the f-holes. The dependences of the sound velocity of the A0 frequency on gaseous temperature and mass were investigated. It was found that the frequency of the A0 mode changed, depending on the molecular weight and the temperature of the gas filling the violin’s body. From these results, it was deduced that a temperature change in the room in which musical instruments are played may be reflected in their tones. The measurement of the A0 modal frequency of a violin, focusing on the molecular weight and temperature of the gas, would be useful to students of physics to help in the understanding of sound velocity.
Quantum robust control theory for Hamiltonian and control field uncertainty*
Authors: Koswara Andrew , Bhutoria Vaibhav , Chakrabarti Raj
Published: May 2021

Quantum robust control—which can employ fast leading order approximations, slower but more accurate asymptotic methods, or a combination thereof for quantification of robustness—enables control of moments of quantum observables and gates in the presence of Hamiltonian uncertainty or field noise. In this paper, we present a generalized quantum robust control theory that extends the previously described theory of quantum robust control in several important ways. We present robust control theory for control of any moment of arbitrary quantum control objectives, introducing moment-generating functions and transfer functions for quantum robust control that generalize the tools of frequency domain response theory to quantum systems, and extend the Pontryagin maximum principle for quantum control to control optimization in the presence of noise in the manipulated amplitudes or phases used to shape the control field. To provide guidelines as to the types of quantum control systems and control objectives for which asymptotic robustness analysis is important for accuracy, we introduce methods for assessing the Lie algebraic depth of quantum control systems, and illustrate through examples drawn from quantum information processing how such accurate methods for quantification of robustness to noise and uncertainty are more important for control strategies that exploit higher order quantum pathways. In addition, we define the relationship between leading order Taylor expansions and asymptotic estimates for quantum control moments in the presence of Hamiltonian uncertainty and field noise, and apply such leading order approximations to significant pathways analysis and dimensionality reduction of asymptotic quantum robust control calculations, describing numerical methods for implementation of these calculations.
Evidence of ‘two plasmon’ decay of energetic particle induced geodesic acoustic mode
Authors: Qiu Zhiyong , Chen Liu , Zonca Fulvio , Falessi Matteo Valerio
Published: May 2021

Secondary low frequency mode generation by energetic particle induced geodesic acoustic mode (EGAM) observed in LHD experiment is studied using nonlinear gyrokinetic theory. It is found that the EGAM frequency can be significantly higher than local geodesic acoustic mode (GAM) frequency in low collisionality plasmas, and it can decay into two GAMs as its frequency approaches twice GAM frequency, in a process analogous to the well-known two plasmon decay instability. The condition for this process to occur is also discussed.
Exact solutions of the (3+1)-dimensional Jimbo-Miwa equation via Wronskian solutions: Soliton, breather, and multiple lump solutions
Authors: Tang Yaning , Liang Zaijun , Ma Jinli
Published: May 2021

In this paper, the Hirota bilinear method is applied to investigate the exact solutions of the (3+1)-dimensional Jimbo-Miwa (JM) equation, including solitons, breathers and lumps, which satisfy specific Wronskian conditions. Their dynamic behaviors and the effects of free parameters on the propagation direction and velocity are analyzed through three-dimensional images and the corresponding contour plots. Especially, based on the 2Mth-order Wronskian determinant solutions, the determinant expression of arbitrary Mth-order lump solutions is constructed by employing elementary transformation and long wave limit. The experimental results show that the interaction between multiple lumps is a completely elastic collision. These results may be helpful to understand the propagation processes of nonlinear waves in some nonlinear physical systems, such as fluid mechanics, nonlinear optics and so on.
Trapping effect for QCD axion dark matter
Authors: Nakagawa Shota , Takahashi Fuminobu , Yamada Masaki
Published: May 2021

In the early universe, the potential of a scalar field can be significantly modified, and the scalar field may be trapped for a long time in a different location than the current vacuum. The trapping effect can increase or decrease the scalar abundance. For instance, in thermal inflation, a scalar field is trapped at the top of the potential by a thermal effect and dominates the universe to drive inflation for a short period of time. On the other hand, a scalar abundance can be exponentially suppressed in the adiabatic suppression mechanism, where a scalar field moves adiabatically by a time-dependent trapping potential. In this study, we investigate such a trapping effect on the abundance of scalar fields. Specifically, we investigate how the abundance of a scalar field depends on its initial position in the case of a double well potential and identify the physical quantity that controls the abundance. Then, we study the QCD axion abundance for various values of the misalignment angle, where the axon potential receives a large temporal mass due to the Witten effect. We find that the axion abundance is suppressed due to the adiabatic suppression mechanism even when it is trapped near the maximum of the potential, if the trapping effect is sufficiently large.
Neutrino and dark matter in a gauged U(1)_R symmetry
Authors: I. Nagao Keiko , Okada Hiroshi
Published: May 2021

We study neutrinos and dark matter based on a gauged U(1)R symmetry in the framework of a radiative seesaw scenario.
We identify the dark matter as a bosonic particle that interacts with the quark and the lepton sectors through vector-like heavier quarks and leptons.
The dark matter also plays a role in generating the neutrino mass matrix with the neutral heavier fermions.
We explore several constraints for the masses and the couplings related to the dark matter by computing the relic density and the scattering cross sections for direct detection methods, taking into consideration neutrino oscillations, lepton flavor violations, and the muon anomalous magnetic moment.
Finally, we mention the semileptonic decays and the neutral meson mixings that occur through the dark matter by one-loop box diagrams.
Cosmological constraints with the Effective Fluid approach for Modified Gravity
Authors: Cardona Wilmar , Arjona Rubén , Estrada Alejandro , Nesseris Savvas
Published: May 2021

Cosmological constraints of Modified Gravity (MG) models are seldom carried out rigorously. First, even though general MG models evolve differently (i.e., background and perturbations) to the standard cosmological model, it is usual to assume a ΛCDM background. This treatment is not correct and in the era of precision cosmology could induce undesired biases in cosmological parameters. Second, neutrino mass is usually held fixed in the analyses which could obscure its relation to MG parameters. In a couple of previous papers we showed that by using the Effective Fluid Approach we can accurately compute observables in fairly general MG models. An appealing advantage of our approach is that it allows a pretty easy implementation of this kinds of models in Boltzmann solvers (i.e., less error-prone) while having a useful analytical description of the effective fluid to understand the underlying physics. This paper illustrates how an effective fluid approach can be used to carry out proper analyses of cosmological constraints in MG models. We investigated three MG models including the sum of neutrino masses as a varying parameter in our Markov Chain Monte Carlo analyses. Two models (i.e., Designer f(R) [DES-fR] and Designer Horndeski [HDES]) have a background matching ΛCDM, while in a third model (i.e., Hu & Sawicki f(R) model [HS]) the background differs from the standard model. In this way we estimate how relevant the background is when constraining MG parameters along with neutrinos' masses. We implement the models in the popular Boltzmann solver CLASS and use recent, available data (i.e., Planck 2018, CMB lensing, BAO, SNIa Pantheon compilation, H
0 from SHOES, and RSD Gold-18 compilation) to compute tight cosmological constraints in the MG parameters that account for deviation from the ΛCDM model. For both the DES-fR and the HS model we obtain log10
b < -8 at 68% confidence when all data are included. In the case of the HDES model we find a somewhat weaker value of log10
Jc
> -5 at 68% confidence. We also find that constraints on MG parameters are a bit weakened when compared to the case where neutrinos' masses are held fixed in the analysis.
Photon-induced correlations of quantum systems via an excitation exchange operator
Authors: Shuker Reuben , Koganov Gennady A
Published: May 2021

The sensitivities of optical magnetometers, atomic clocks and atom interferometers and other quantum metrology devices, whose signals are linear in the number N of active atoms, have practically arrived at their theoretical limit. Further enhancement of the sensitivities of such devices requires the introduction of new physical processes to improve on their present achievements. Many-body collective correlation among the atoms, spins or, in general, quantum systems may prove to be a suitable method. As such correlations introduce interference terms in the intensity of the scattering amplitudes they may enhance the signal as N(N − 1) for N correlated quantum systems. These correlations enhance the signal to noise ratio by a factor of N
2 and contribute to better sensitivity in quantum metrology. Moreover, atomic correlation may provide a quantum noise limit, the Heisenberg limit. In the present letter a novel operator is introduced that expresses photon-induced excitation exchange that takes into account energy conservation,

V

i
j

=

a
ˆ

†

σ
i

σ
j
†

a
ˆ

, where

σ
i

=

g

i

e

i

is the lowering operator of the i-th atom, and

a
ˆ

†

,

a
ˆ

are photon creation and annihilation operators. Here i and j stand for two different atoms. This operator describes real or virtual photon-assisted excitation exchange between two atoms. Moreover, it conserves the total number of excitations in the joint electromagnetic field and the quantum system. A photon-induced excitation exchange between two atoms is calculated and clearly exhibits correlation and collective effects.
Modelling the sputtering and reflection from a beryllium surface: atomistic analysis
Authors: Shermukhamedov Shokirbek , Chen Lei , Nazmutdinov Renat , Kaiser Alexander , Probst Michael
Published: May 2021

Sputtering from plasma-facing surfaces upon particle impact can limit the lifetime of components in fusion devices, especially in the diverter region. Atomistic simulations of the processes associated with plasma–wall interactions allow for a detailed analysis of sputtering, reflection and adsorption. Most former works of beryllium sputtering by hydrogen isotopes were aimed mostly on the sputtering yield. We investigate the influence of impact energy and angle on sputtering, and analyze these quantities also for the outgoing particle. We model the sputtering by non-cumulative molecular dynamics simulations with a large number of trajectories for the various parameters. The underlying forces and energies are obtained from high-dimensional neural networks fitted to density functional calculations. We find a good agreement with the previously reported sputtering yields for perpendicular impact and a qualitative accordance with experimental data. In detail, the sputtering yield increases with increasing impact energy for angles of incidence larger than 45° with respect to the surface normal, while smaller angles show a maximal yield up to 100 eV. In cases where D reflection rather than sputtering occurs, a similar pattern is found for all angles, with the maximal reflection rate at 80°.
The future evolution of energy-water-agriculture interconnectivity across the US
Authors: Khan Zarrar , Wild Thomas B , Iyer Gokul , Hejazi Mohamad , Vernon Chris R
Published: May 2021

Energy, water, and agricultural resources across the globe are highly interconnected. This interconnectivity poses science challenges, such as understanding and modeling interconnections, as well as practical challenges, such as efficiently managing interdependent resource systems. Using the US as an example, this study seeks to define and explore how interconnectivity evolves over space and time under a range of influences. Concepts from graph theory and input–output analysis are used to visualize and quantify key intersectoral linkages using two new indices: the ‘Interconnectivity Magnitude Index’ and the ‘Interconnectivity Spread Index’. Using the Global Change Analysis Model (GCAM-USA), we explore the future evolution of these indices under four scenarios that explore a range of forces, including socioeconomic and technological change. Analysis is conducted at both national and state level spatial scales from 2015 to 2100. Results from a Reference scenario show that resource interconnectivity in the US is primarily driven by water use amongst different sectors, while changes in interconnectivity are driven by a decoupling of the water and electricity systems, as power plants become more water-efficient over time. High population and GDP growth results in relatively more decoupling of sectors, as a larger share of water and energy is used outside of interconnected sector feedback loops. Lower socioeconomic growth results in the opposite trend. Transitioning to a low-carbon economy increases interconnectivity because of the expansion of purpose-grown biomass, which strengthens the connections between water and energy. The results highlight that while some regions may experience similar sectoral stress projections, the composition of the intersectoral connectivity leading to that sectoral stress may call for distinctly different multi-sector co-management strategies. The methodology we introduce here can be applied in diverse geographical and sectoral contexts to enable better understanding of where, when, and how coupling or decoupling between sectors could evolve and be better managed.
Do political systems have a lasting effect on climate change concern? Evidence from Germany after reunification
Authors: Kountouris Yiannis
Published: May 2021

Support for climate policy depends on the public’s perception of climate change costs. Assessing the determinants of climate change attitudes contributes to explaining cross-country differences in climate policy implementation. In this paper, I examine the influence of experience with a political system on individuals’ concern for the consequences of climate change. To address biases introduced by the endogeneity of the political system, I use the natural experiment created by the division and reunification of Germany. I find evidence suggesting that experience with the political system of East Germany has a lasting negative effect on climate change concern that is discernible more than 20 years after reunification. Results suggest that the influence of political institutions on climate change attitudes and policy adoption can persist long after they have been replaced.
Increasing heat risk in China’s urban agglomerations
Authors: Zhang Guwei , Zeng Gang , Liang Xin-Zhong , Huang Cunrui
Published: May 2021

A heat danger day is defined as an extreme when the heat stress index (a combined temperature and humidity measure) exceeding 41 °C, warranting public heat alerts. This study assesses future heat risk (i.e. heat danger days times the population at risk) based on the latest Coupled Model Intercomparison Project phase 6 projections. In recent decades (1995–2014) China’s urban agglomerations (Beijing-Tianjin-Hebei, Yangtze River Delta, Middle Yangtze River, Chongqing-Chengdu, and Pearl River Delta (PRD)) experienced no more than three heat danger days per year, but this number is projected to increase to 3–13 days during the population explosion period (2041–2060) under the high-emission shared socioeconomic pathways (SSP3-7.0 and SSP5-8.5). This increase will result in approximately 260 million people in these agglomerations facing more than three heat danger days annually, accounting for 19% of the total population of China, and will double the current level of overall heat risk. During the period 2081–2100, there will be 8–67 heat danger days per year, 60%–90% of the urban agglomerations will exceed the current baseline number, and nearly 310 million people (39% of the total China population) will be exposed to the danger, with the overall heat risk exceeding 18 times the present level. The greatest risk is projected in the PRD region with 67 heat danger days to occur annually under SSP5-8.5. With 65 million people (68% of the total population) experiencing increased heat danger days, the overall heat risk in the region will swell by a factor of 50. Conversely, under the low-emission pathways (SSP1-2.6 and SSP2-4.5), the annual heat danger days will remain similar to the present level or increase slightly. The result indicates the need to develop strategic plans to avoid the increased heat risk of urban agglomerations under high emission-population pathways.
Sensitivity of seasonal migration to climatic variability in central India
Authors: Choksi Pooja , Singh Deepti , Singh Jitendra , Mondal Pinki , Nagendra Harini , Urpelainen Johannes , DeFries Ruth
Published: May 2021

Extreme climatic events and variability are on the rise around the world, with varying implications for populations across socio-economic conditions. Effective strategies for climate adaptation and development depend on understanding these differential sensitivities to climatic variability. This study focuses on a vulnerable population living in forest-fringe villages of central India, where seasonal migration is a common livelihood strategy for poor households to supplement their incomes with remittances. We quantify the relative sensitivity of a decision to migrate for the first time to climate and socio-economic variables and how the sensitivities vary for different segments of the population. We surveyed 5000 households in 500 forest-fringe villages to identify patterns of migration from 2013 to 2017. Using a mixed-effects logistic regression model, we predicted the probability of first-time migration of a household member based on climate variables and household- and district-level characteristics. We find that households in more agricultural and prosperous districts experience lower rates of migration but are more sensitive to climatic variability than households in poorer districts. The probability of first-time migration from a household in the most prosperous district increases by approximately 40% with one standard deviation in mean maximum temperature or rainfall from the 1981–2017 mean. However, the probability of migration does not vary as a function of climatic variability for households in the poorest district. We attribute this difference in sensitivities to the greater dependence on agriculture and irrigation in more prosperous districts and poverty-driven dependence on migration regardless of the climate in poorer districts. Households investing remittances from migration in agricultural intensification could become increasingly sensitive to climate variability, particularly with water shortages and projected increases in climate variability in the region. Promotion of non-agricultural livelihood options and climate-resilient agriculture could the reduce sensitivity of migration to climate variability in the study region.
Papaya peels as source of hydro char via hydrothermal carbonization
Authors: Hamid N A A , Zulkifli N Z
Published: May 2021

Papaya peels was converted into hydro char via hydrothermal carbonization (HTC) and used as adsorbent for methylene blue removal. The carbonization of the papaya peels was executed at six different temperatures ranging from 150 °C to 200 °C with 50 °C interval with reaction time of 120 minutes mainly to study the effect of the carbonization temperature on the hydro char formed via HTC. The hydro char produced was assessed in terms of mass yield, elemental compositions, and higher heating value (HHV) prior to degradation of methylene blue (MB). For all sample, the mass yield of the hydro char was reduced as the reaction temperature increased whilst contradict to carbon contents which increased as the HTC temperature increased. The HHV also increased as the carbonization temperature rise, but it was observed a slight decline of the HHV for hydro char formed at 170 °C which because of the carbon content in the hydro char. Moreover, result shows removal percentage of MB increased significantly along with the carbonization temperature.
Potential health risk assessment of heavy metal content in Perlis soil
Authors: Ahmad N A , Ali U F M , Chan M F
Published: May 2021

A determination of soil heavy metal (Cu, Mn and Ni) concentrations in Perlis state, Malaysia was performed to define the level of soil pollution. Six soil samples were collected at depth of 0 – 15 cm in industrial, residential and school areas around Perlis. The highest concentration of Mn (57.80 mg/kg) and Ni (2.83 mg/kg) were detected at limestone quarry in Bukit Air, Cu (17.43 mg/kg) in Kampung Wang Ulu. The concentration of Cu, Mn and Ni were well below their soil geochemical background values. The single pollution indices assessment revealed that the soil contamination due to heavy metals in Perlis is insignificant. On the basis of the heavy metal content, the potential health risk assessment for children and adults was calculated for a lifetime of exposure through ingestion, inhalation and dermal contact based on the USEPA model. The exposure assessment found that the exposure pathways of heavy metals to both children and adults are through ingestion. Both Hazard Quotient (HQ) and Hazard Index (HI) values are lower than 1, indicating no health risk. From the result, the HI values indicated that the soil heavy metal contamination could pose more impacts on children as compared to adults.
Comparison of sawdust and kenaf core fibre as cultivation substrates for grey oyster (Pleurotus sajor-caju) and black jelly (Auricularia auricular-judae) mushrooms
Authors: Ibrahim R , Shaharudin N F U
Published: May 2021

Unlike plants, mushrooms are heterotrophic organisms which require external nutrients to grow the hypha network which supplies nutrients for the growth of reproductive stage. In this study, rubber tree sawdust, kenaf core fibre and mixture of sawdust-kenaf (50:50) were used as the cultivation substrates for grey oyster (Pleurotus sajor-caju) and black jelly (Auricularia auricula-judae) mushrooms. Kenaf (Hibiscus cannabinusL.) composed of fibre-rich substances which consist of an internal woody core and a superficial fibrous bark. This study was conducted to compare between sawdust and kenaf core fibre as the cultivation substrates in terms of growth performance, yield and postharvest quality of grey oyster and black jelly mushrooms. There was no significant difference (P≥0.05) observed in the mycelium growth rate among the substrates used. However, grey oyster mushroom showed higher growth rate 0.74-0.77 cm/day) compared to black jelly mushroom (0.44-0.55 cm/day). Sawdust substrate showed the highest yield (415.5 g) for both mushroom species followed by mixture of sawdust-kenaf and lastly kenaf. There was also no significant different (P≥0.05) found in the postharvest quality of both mushrooms species among different substrates used. In conclusion, in terms of yield, sawdust was the best mushroom cultivation substrate for both grey oyster and black jelly mushrooms.
A comparative study on bioethanol production from rice straw and banana pseudostem through simultaneous saccharification and fermentation using Kluyveromyces marxianus
Authors: Gatdula K M , Blaquera M S F N , Jimena C M V , Elegado F B , Alcantara J Z , Guerrero G A M
Published: May 2021

To improve the efficiency of second-generation bioethanol production, simultaneous Saccharification and Fermentation (SSF) of top agricultural wastes in the Philippines such as rice straw and banana pseudostem was conducted using commercial enzymes and the thermotolerant yeastKluyveromyces marxianus. Residues were initially subjected to chemical treatment prior to SSF. A constant inoculum loading of 10% vv-1was introduced during SSF, and mixed with a nutrient supplemented solution. Aside from the enzyme loading, the effect of reaction temperature and reaction time on ethanol concentration was assessed. Among the tested parameters, only reaction time had a significant effect on the bioethanol concentration from both biomasses. For a pre-treated rice straw with 70.93% ww-1holocellulose, highest ethanol concentration obtained was 6.30+0.44 gL-1at 45°C, reaction time of 48 h and with enzyme loading of 30 FPUg-1. On the other hand, 5.35+0.29 gL-1ethanol was achieved from SSF of banana pseudostem with 67.75% ww-1holocellulose, also at 35°C, at a lower reaction time of 24 h and same enzyme loading of 30 FPUg-1. This study also proves that the thermotolerantK. marxianuswas capable of producing bioethanol from lignocellulosics through SSF, thereby considering it as a potential alternative toSaccharomyces cerevisiaefor bioethanol production.
Changes in the physical and chemical properties of C. nutans herbal leaves dried under different drying methods
Authors: Abdullah S , Nordin R , Rzemin M A A , Razak N Abdul
Published: May 2021

Drying is a well-known preservation method that uses to extent the shelf life of food materials during storage. In herbal industry, the drying is conducted by using several methods. It is believed that drying methods could affect the herbs physical and chemical properties. In this project, the effects of different drying methods on colour changes, rehydration ratio and bioactive constituent of C. nutans herb were investigated. The herb was dried under sunlight, shade, vacuum oven, and microwave. Results showed that the dried leaves have better retention of TPC and higher antioxidant activity as compared to the fresh leaves. Vacuum oven dried samples showed the highest antioxidant activity and significantly high in TPC. Besides, vacuum and under shade dried herbal leaves had no significant effect on the colour changes. Moreover, leaves dried under vacuum oven was also observed to exert the highest rehydration ratio due to less cell breakdown during drying. Therefore, vacuum drying has greater performance in term of retaining colour, less microstructure changes and greater TPC and antioxidant activity. It could be suggested that by adding vacuum to other drying methods may able to enhance the herbal quality.
Tomato peel-cutin based film mitigates the deterioration of calamansi (Citrofortunella microcarpa)
Authors: Madzuki I N , Tan J M , Shalan N A A Mohamad , Isa N S Mohd
Published: May 2021

The plant cuticle, cutin is the main component in tomato peel. The cutin was obtained through 3% (w/v) NaOH extraction by autoclave. The extract was then mixed with pectin, forming a film suspension before being used as a coating for calamansi. The calamansi samples were grouped (n=20) into: pectin; 1:1 pectin/cutin; 2:3 pectin/cutin; 3:2 pectin/cutin; and uncoated control. The calamansi were stored at 25°C for 10 days and were analysed for physio-chemical changes every two days. Calamansi samples coated with pectin/cutin showed a significant reduction in firmness and Brix as early as day 2 and the percentage of citric acid at day 6. After 10 days of storage, the 2:3 pectin/cutin treatment samples showed minimum changes in weight loss (23.52±3.20%), firmness (27.11±3.10 N), total soluble solids content (7.55±0.21°Brix), titratable acidity (25.60±0.32% citric acid) and colour. Therefore, it can be concluded that the 2:3 pectin/cutin film coating was the best treatment for harvested calamansi in attenuating the deterioration process.
Acetogenic Removal Efficiency of POME Under the Influence of Electromagnetic Field
Authors: Wajdi M , Muda K
Published: May 2021

Palm oil mill effluent (POME) is categorized as high strength wastewater. The current treatment technology for POME is mostly depends on biological treatment through anaerobic and aerobic processes. Application of magnetic field was reported able to show effective removal performance of pollutant. The exposure of magnetic field will cause changes on the physical and chemical properties on a molecular level. The main objective of this research is to evaluate the application of EMF to enhance the performance of acetogenic microbes towards POME treatment. In this study, the EMF was evaluated in batch reactor system under an anaerobic acetogenic condition followed by aerobic reaction phase to treat POME. The hydraulic retention time and the intensity of EMF applied in this study were five days and ±15 mT respectively. The results indicated that using EMF improves the removal performance of color by 19%, chemical oxygen demand (COD) by 28%, ammonia nitrogen by 13%, nitrite by 17% and nitrate by 31%. Ultimately, the application of EMF helps to enhance anaerobic acetogenic bacteria and then enhanced the overall removal performance.
Effects of incorporation of essential oil into film for fruit packaging application
Authors: Hashim R H R , Gunny A A N , Sam S T , Kamaludin N H I , Shamsuddin M R
Published: May 2021

Biodegradable composite films with antimicrobial properties consists of three biopolymers (polysaccharides, proteins, fats), additives (plasticizers, emulsifiers), and synthetic or natural antimicrobial. Biodegradable packaging embedded in food products with antimicrobial agent such as essential oils (EOs) is an innovative green technology based on a novel approach to substitute conventional and synthetic petroleum packaging. Good packaging is necessary to prevent spoilage during postharvest stage. Introducing EOs onto the fruit packaging films strongly inhibiting bacterial and fungal activities on the fruit products and gives positive effect on the storage of the products. This review focuses on the contribution of the incorporation of EOs and biodegradable films to prolonging the shelf life of fruit products in addition to reduce the risk of growth of pathogenic bacteria on the surface of fruit products. Essential oils incorporated into film provides a new strategy and improves efficiency of fruit packaging film in enhancing quality and shelf life of post-harvest fruit products.
Removal of Copper and Magnesium Cations from Aqueous Solutions by Clinoptilolite Zeolite Adsorption
Authors: Aziz R A , Fauzi N F N , Salleh M N , Saleh M
Published: May 2021

The aim of this study is to determine the potentials of clinoptilolite zeolite in removing selected heavy metals, that are copper and magnesium in aqueous solutions. The removal of both metal cations has been studied by using the batch techniques. Three experimental variables were carried out under predetermined conditions of contact time (20 – 100 minutes), effect of dosage (0.20 – 1.00 gram), and effect of pH solution (pH 2 to 10). Adsorption capacity of zeolite towards heavy metal removal was then determined at various initial concentrations of metal ions between 20 to 100 ppm. Results obtained shows that adsorption of Cu 2+ and Mg 2+ on zeolite has been shown to depend significantly on the pH, adsorbent amount and contact time. The significant value of pH was reached at pH 6, followed by 1 hour of contact time for 1 gram of adsorbent; for both metal ions studied. Studies on the rate of uptake of heavy metal ions by the zeolite indicated that the process was quite rapid and maximum adsorption occurred within the first hour of contact. The results show that high silica zeolite such as clinoptilolite is a promising adsorbent as they combine high adsorption capacities and molecular sieve properties.
Physicochemical Characteristics of Activated Carbon Impregnated with Different Type of Metal Oxide Nanoparticles towards Hydrogen Sulfide Removal
Authors: Azamuddin M F A , Abdullah N , Mohamad Nor N
Published: May 2021

It is highly anticipated to understand the influence of physicochemical characteristics of different types metal oxide nanoparticles impregnated onto palm shell activated carbon (PSAC) adsorbent towards hydrogen sulfide (H 2S) removal. Alkaline precipitation method was used to synthesis metal oxide nanoparticles (CeO 2, NiO, CuO, and Fe 2O 3). The synthesised metal oxide nanoparticles were then impregnated in the pre-oxidized PSAC adsorbents (Ce/PSAC, Ni/PSAC, Cu/PSAC and Fe/PSAC). The prepared adsorbent was then analysed via Scanning Electron Microscope – Energy Dispersive X-ray (SEM-EDX), Thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR) and H 2S adsorption analysis. Based on H 2S adsorption study, different types of metal oxide nanoparticles impregnated on PSAC adsorbent showed different trend of breakthrough time and adsorption capacity. PSAC adsorbent that was modified with metals oxide nanoparticles shows efficient result compared to raw PSAC adsorbent. Among metal oxide nanoparticles, Cu/PSAC adsorbent gives the higher adsorption capacity (86.60 mg H 2S/g Cu/PSAC) and breakthrough time (80 minutes) compared to the rest of adsorbents.
Effect of banana peel waste concentration and mixing rate to the tensile strength of polyvinyl alcohol/banana peel waste composite film: optimization study via statistical tool
Authors: Ng Q H , Kalaiarasi V , Teoh Y P , Ooi Z X , Shuit S H , Low C Y
Published: May 2021

Plastic bags are essential in human’s life on a daily basis. Most of the packaging materials used today are petroleum based manufactured polymers which are non-biodegradable. These polymers contribute to the landfill and take millions of years to decay. Decomposition of these plastics would also release harmful gases into the environment. On the other hand, readily available degradable plastics are expensive. Therefore, the purpose of this research is to produce a biodegradable film as a substitution for the commercial biodegradable plastics to overcome such problem. A series of biodegradable polymer films derived from polyvinyl alcohol (PVA) embedded with banana peel waste (BPW) was prepared by solution casting method. The BPW was introduced as a promoter of biodegradability of the PVA. It was found that as the amount of BPW increases, the colonies of the fungal growth on the film showed a corresponding increase, indicating higher biodegradability of the PVA composite film. The blended films with different compositions of BPW were evaluated for their tensile properties using one-factor-at-a-time (OFAT) technique and hence optimized via response surface methodology (RSM). The tensile strength of the PVA/BPW films (32.52–46.97 MPa) was found to be lower than those of unfilled PVA film (80.30 MPa). The best composition of BPW filler in this study was found to be 5.1% with respect to PVA and it is compatible to be used as a film in daily uses.
Biosorption of copper ions from aqueous solution using Kappaphycus striatum
Authors: Mun N K , Mokhtar  , Shoparwe N F , Shukor H
Published: May 2021

Biosorption is an eco-friendly alternative technology for the removal of heavy metals from industrial waste and effluents using low-cost and effective biosorbent. Abundant of natural materials like agricultural biomass, industrial waste, and microbial biomass can be used as a promising biosorbent. In the present study, red algae Kappaphycus striatum biomass will be used for the adsorption of copper ions in aqueous solution. The free (non-immobilized) and immobilized form of red algae Kappaphycus striatum biomass and biosorption rate were investigated for the adsorption process. The maximum biosorption of copper ions was achieved when immobilized form of algae biomass were used at the condition pH of 5, biomass dosage, 0.25 g/L, contact time of 90 minutes, and at the temperature of 50 °C with a 65.8% of removal. The experiment data for biosorption rate with time also was used to evaluated two kinetic models (pseudo-first-order and pseudo-second-order) and two isotherm models (Langmuir and Freundlich). The results reveal that metallic ions biosorption on the immobilized Kappaphycus striatum followed the pseudo-second-order kinetic model with a R 2=0.9996 and Langmuir isotherm model with a R 2=0.9999. The present work shows that the red algae of Kappaphycus striatum as a potential biosorbent for the removal of heavy metal ions from aqueous solution.
The effect of stearic acid and different loading treated and untreated EFB fiber on the tensile, structural and chemical properties of polypropylene/recycled acrylonitrile butadiene rubber/empty fruit bunch composites
Authors: Santiagoo R , Hong T W , Azizan N Z N , Andrew A M , Wahab F , Seman N A A , Othman N S
Published: May 2021

A new developed of polymer materials made up of polypropylene (PP), recycled nitrile gloves (NBRr) and empty fruit bunch (EFB) fiber was fabricated. Recycled nitrile glove was blended together with PP plastic to reduce the use of petroleum based and to solve the issue of waste discarded at the landfill. EFB fiber was incorporated to lower the production cost of composite. Due to incompatibility of different phases, stearic acid treatment was used to improve the EFB fiber polarity. Thus, the effect of different EFB loading for untreated and treated stearic acid of PP/NBRr/EFB composite was studied. In this work, all the materials were mixed well using a heated two roll mill with temperature 180 °C within 9 minutes. The EFB loading were varied from 0 to 30 phr. The analysis of tensile properties was tested followed the ASTM D638, Type IV, testing procedure, to analyze tensile strength, Young’s modulus and elongation at break. The structural properties of the fracture sample surfaces were observed using Scanning Electron Microscope (SEM) and the chemical properties was analyzed using Fourier Transform Infra-Red (FTIR). Composites with stearic acid treatment have shown higher tensile strength compared to untreated EFB fiber. Besides, the micrograph structure surface from scanning electron microscopy analysis showed better fiber and matrix interaction, as the treated-EFB fiber is well encapsulated with the PP matrix. From the FTIR analysis, the intensity peak of OH for PP/NBRr/EFB/SA was reduced due to the removal O-H bond of cellulose from fibers during the surface modification of fibers.
Effect of inulin addition in cucumber drinks on urease inhibitory, antioxidant activity and its consumer acceptability
Authors: Kasim K F , Shaharuddin Z S , Amer N A Mohd , Bahari R , Abdullah A A , Mohamad C W S R , Sofian-Seng N S
Published: May 2021

Cucumber (Cucumis sativus) juice is the best rejuvenation tonic used in the folk medicine. However, during juicing, all the fibre content of the juice will be removed. Addition of inulin to the juice not only help to replace the fibre content but it also acts as prebiotic which may help to stimulate the growth of beneficial bacteria in guts. Therefore, this study focused on the effect of inulin addition in the cucumber drink on urease inhibitory and antioxidant activities, as well as on consumer acceptability. Cucumber drink was prepared using a domestic juicer and the different amounts of inulin added to the drink were based on the nutritional conditions for dietary fibre claims of a food product as a ‘source of fibre’ and ‘high fibre’ (i.e. 3 g/100 mL and 6 g/100 mL, respectively). Urease inhibitory activity was determined using phenol-hypochlorite reaction and antioxidant activity was determined using DPPH radical scavenging assay. The results show that non-fortified cucumber juice (100% without inulin) had the highest urease inhibitory and DPPH radical scavenging activities (95.1% and 38.3%, respectively). The results show that the addition of inulin to the cucumber drink does not have any impact on the urease inhibitory and DPPH radical scavenging activities. On the other hand, consumer acceptance test shows that cucumber drinks fortified with 6 g of inulin were more acceptable to the consumer based on consumers’ 9-point hedonic scale distribution.