bluuebunny/crossref_metadata_2025 huggingface dataset:
Biomechanical factors in three-dimensional tissue bioprinting
Authors: Ning Liqun , Gil Carmen J. , Hwang Boeun , Theus Andrea S. , Perez Lilanni , Tomov Martin L. , Bauser-Heaton Holly , Serpooshan Vahid
Published: December 2020

3D bioprinting techniques have shown great promise in various fields of tissue engineering and regenerative medicine. Yet, creating a tissue construct that faithfully represents the tightly regulated composition, microenvironment, and function of native tissues is still challenging. Among various factors, biomechanics of bioprinting processes play fundamental roles in determining the ultimate outcome of manufactured constructs. This review provides a comprehensive and detailed overview on various biomechanical factors involved in tissue bioprinting, including those involved in pre, during, and post printing procedures. In preprinting processes, factors including viscosity, osmotic pressure, and injectability are reviewed and their influence on cell behavior during the bioink preparation is discussed, providing a basic guidance for the selection and optimization of bioinks. In during bioprinting processes, we review the key characteristics that determine the success of tissue manufacturing, including the rheological properties and surface tension of the bioink, printing flow rate control, process-induced mechanical forces, and the in situ cross-linking mechanisms. Advanced bioprinting techniques, including embedded and multi-material printing, are explored. For post printing steps, general techniques and equipment that are used for characterizing the biomechanical properties of printed tissue constructs are reviewed. Furthermore, the biomechanical interactions between printed constructs and various tissue/cell types are elaborated for both in vitro and in vivo applications. The review is concluded with an outlook regarding the significance of biomechanical processes in tissue bioprinting, presenting future directions to address some of the key challenges faced by the bioprinting community.
High-performance flexible WSe2 flake photodetector with broadband detection capability
Authors: Ma Yinfei , Liu Dan , Hao Jianxin , Wang Li , Wang Wei
Published: December 2020

In this age of interconnection, photodetectors based on two-dimensional materials have been widely used in wearable physiological monitoring systems and wireless sensor networks. Hence, this paper proposes a novel WSe2 flake photodetector with a metal–semiconductor–metal structure. The photodetector achieved a high responsivity (Ri) of 2.46 A/W under the condition of an external bias voltage at 650 nm as well as an ultra-high detectivity (D*) of 0.76 × 1011 Jones. The photodetector overcomes the shortcomings of traditional photoelectric detectors with large dark currents. A small dark current of ∼1 nA was obtained, which also creates an opportunity for future high-performance photoelectric devices. After 500 bending cycles, the current and dark current of the device decreased only by 1.7%. Additionally, a self-built test platform indicated that the test device has a device response time of up to 6.51 ms, which creates an opportunity for the high-speed corresponding photoelectric devices based on WSe2 flakes in the future.
Functional magnetic ferrogels: From biosensors to regenerative medicine
Authors: Kurlyandskaya G. V. , Blyakhman F. A. , Makarova E. B. , Buznikov N. A. , Safronov A. P. , Fadeyev F. A. , Shcherbinin S. V. , Chlenova A. A.
Published: December 2020

Polyelectrolyte gels and ferrogels (FG) are attracting special interest in biomedicine. Here we describe our experience developing functional magnetic ferrogels for regenerative medicine and magnetoimpedance biosensing for measuring stray fields of nanoparticles in FG with a multilayered sensitive element. We discuss the possibility of developing a new generation of drug delivery systems for magnetic field assisted delivery, positioning and biosensing.
Magnetic nanowires for quantitative detection of biopolymers
Authors: Zamani Kouhpanji Mohammad Reza , Stadler Bethanie J. H.
Published: December 2020

Magnetic nanowires (MNWs) rank among the most promising multifunctional magnetic nanomaterials for nanobarcoding applications, especially biolabeling, owing to their nontoxicity and remote excitation using a single magnetic source. Until recently, the first-order reversal curve (FORC) technique has been broadly used to study the MNWs for biolabeling applications. However, since FORC measurements require many data points, this technique is very slow which makes it inapplicable for clinical use. For this reason, we recently developed a fast new framework, named the projection method, to measure the irreversible switching field (ISF) distributions of MNWs as the magnetic signature for the demultiplexing of magnetic biopolymers. Here, we illustrate the ISF distributions of several MNWs types in terms of their coercivity and interaction fields, which are characterized using both FORC and projection methods. Then, we explain how to tailor the ISF distributions to generate distinct signature to reliably and quantitatively demultiplex the magnetically enriched biopolymers.
Two-dimensional overdamped simulations of droplet solitons activated by spin transfer torque
Authors: Chaves-O’Flynn Gabriel D. , Stein D. L.
Published: December 2020

We present overdamped micromagnetic simulations of the time evolution of magnetic droplet solitons which are formed in a thin film with perpendicular magnetic anisotropy by injecting a spin polarized current through a circular nanocontact. The overdamped dynamics help explore the effective energy landscape of these structures and permit identification of stationary states that are either energy extrema or saddle configurations. Our micromagnetic simulations start with configurations that are numerical solutions of a one-dimensional model where the magnetization depends only on the radial distance to the center of the nanocontact. We verify that these solutions correspond either to energy minima or saddle states, and use them to estimate thermal activation barriers for various current strengths. From the two-dimensional micromagnetic simulations, we identify a new persistent state which does not appear in the one-dimensional model.
Distributed magnetic sensor using reflection coefficients from both ends of single magnetic coaxial cable
Authors: Takenaka Kazuma , Noguchi Naoki
Published: December 2020

The principle of the distributed magnetic sensor by magneto-impedance effect with time domain reflectometry was demonstrated, and the position and strength of the magnetic field were detected simultaneously with a magnetic coaxial cable. This paper presents a distributed magnetic sensor using the forward and reverse reflection coefficients S11 and S22 from both ends of a single magnetic coaxial cable. The method using reflection coefficients includes novel features such as: (1) improvement of the signal-noise ratio for equivalent measurement time and (2) cancellation of the time fluctuation by jitter. It is confirmed that the SNR of a reflected wave with a vector network analyzer is improved by 21.3 dB compared to that of an oscilloscope. Furthermore, the attenuation of a signal wave can be compensated by synthesizing the reflected waves from both ends. As a result, the signal wave is less affected by the attenuation along the length of the cable and is improved by 19.0 dB at the position of 180 mm.
“It’s Us Doing It!” The Power of Participatory Action Research in Prison: A Contradiction in Terms? – Phase 1
Authors: Haarmans Maria ,   PAR Team (Aaron, Dean, Iain, KT, Lee, Paul, Stefan, Steven), Perkins Elizabeth , Jellicoe-Jones Lorna
Published: December 2020

We describe and reflect upon the process of setting up participatory action research (PAR) with a group of men resident on a personality assessment and treatment service in a medium security prison for male offenders. The service is part of the national offender personality disorder (OPD) pathway, a joint initiative between the National Health Service England and Her Majesty’s Prison & Probation Service set up in 2011. Its aim was to provide a pathway of services for offenders, likely to be diagnosed with a personality disorder, to reduce risk of re-offending and improve psychological health and wellbeing. Consistent with PAR principles, prisoners were trained as co-researchers with the aim of co-producing new knowledge and improving their community. To our knowledge, this is the first PAR project conducted within the OPD pathway. We focus here on initial stages of research design and development. By sharing our experiences, we contribute to the literature on co-production research highlighting key benefits and challenges of PAR in this setting. Key learnings such as the importance of obtaining organizational support, taking time for establishing trust, relationship-building and research training are discussed.
Bidirectional controlled quantum teleportation of multi-qubit entangled states via five-qubit entangled state
Authors: Verma Vikram
Published: December 2020

Several schemes for bidirectional controlled quantum teleportation (BCQT) of arbitrary single-qubit states have been proposed by utilizing five-qubit entangled states, six-qubit entangled state and seven-qubit entangled state as the quantum channels. In this paper, a generalization to BCQT of multi-qubit entangled states is presented. By using a five-qubit entangled state as the quantum channel, we propose a scheme for BCQT of certain class of multi-qubit entangled states in which two legitimate users exchange their unknown multi-qubit entangled state to each other with the help of a supervisor. Compared with previous BCQT (3 ↔ 3) scheme [2019 Int. J. Theor. Phys. 58 3594], our proposed BCQT (m ↔ n) scheme requires less consumption of quantum and classical resources, and possesses higher intrinsic efficiency. Also, the present BCQT scheme is more general and has less operation complexity.
Tunnelling based birefringent phase sensitivity through dynamic chiral medium
Authors: Arif Syed Muhammad , Bacha Bakht Amin , Wahid Umer , Ullah Arif , Haneef Muhammad
Published: December 2020

The absorption coefficients, refractive/group indices, phase shifts and fractional change of birefringence beams through dynamic chiral atomic medium are investigated under the effect of quantum tunnelling. The birefringence of phase indices

Δ
n
=

n

r

(
+
)

−

n

r

(
−
)

and group indices

Δ

n

g

=

n

g

(
+
)

−

n

g

(
−
)

are controlled and modified through induced dynamic chiral medium by tunnelling effect. The group indices

n

g

(
±
)

=
±
500

and group velocities

v

g

(
±
)

=
±
c

/

500

are reported with the tunnelling effect. The maximum change in birefringent phase shifts is calculated to 5 microradian with tunnelling frequency at a speed of v = 10 cm/s of the chiral medium in the right circularly polarized (RCP) and left circularly polarized (LCP) beams. A 60% fractional change in the phase shift of RCP and LCP beams are investigated through induced chiral medium when the medium is at rest and when it is moving with the speed of v = 10 cm/s. These results will play an important role in scatterplate phase shifting interferometry.
Superregular solutions for a coupled nonlinear Schrödinger system in a two-mode nonlinear fiber
Authors: Tian He-Yuan , Tian Bo , Yuan Yu-Qiang , Zhang Chen-Rong
Published: December 2020

For the increase of the transmission capacity in optical communication systems, the so-called few-mode fibers are used for people to design the mode division multiplexing transmission. In this paper, we analytically obtain and graphically display the superregular solutions for a coupled nonlinear Schrödinger (NLS) system which describes the wave evolution in a two-mode nonlinear fiber, where the superregular solutions are the analogue of superregular breathers for certain scalar NLS-type equations. On the nonzero-zero (or proportional nonzero-nonzero) background, regular solutions describe the regular nonlinear waves which are located in a finite t domain but do not perturb the background with t being big enough, and superregular solutions are a subset of regular solutions which describe the nonlinear superposition of breathers and dark-bright (or breather-like) solitons developing from the perturbations on the dark-bright (or breather-like) solitons at a certain z, where z and t denote the evolution dimension and temporal distribution dimension, respectively. On the nonzero-zero background, superregular solutions are constructed in three cases: trivial case, a pair of breathers case and single breather case, and then other superregular solutions could be constructed according to the analyses for such three cases. Superregular solutions on the proportional nonzero-nonzero background are derived via the superregular solutions on the nonzero-zero background and an orthogonal transformation.
Analysis of Caputo-Fabrizio fractional order semi-linear parabolic equations via effective amalgamated technique
Authors: Ullah Saif , Zulfiqar Sana , Buhader Anum Aish , Khan Najeeb Alam
Published: December 2020

The significance of semi-linear parabolic equations in various fields of physics and chemistry is perpetual. Literature is enriched with the modeling and numerical investigations of their various paradigms. In this paper, a class of semi-linear diffusion equations is considered as prototypical semi-linear parabolic equation. The equations are reformulated to fractional order derivative by applying Caputo-Fabrizio time fractional derivative (CFTFD). Moreover, an amalgamated technique, that is, a semi-analytical technique is also established, which is combination of Laplace transform and Picard’s iterative method (LTPIM). Specifically, it is designed to effectively simulate the governing semi-linear diffusion equations. In addition, the stability analysis of this amalgamated technique is also carried out through comparison with Banach fixed point theorem andH-stable mapping. The obtained results are illustrated graphically and in tabulated form, which evidently validates the proficiency of this technique for semi-linear parabolic equations.
Continuous droplet rebound on heated surfaces and its effects on heat transfer property: A lattice Boltzmann study*
Authors: Zhang Qing-Yu , Dong Qi-Peng , Wang Shan-Lin , Wang Zhi-Jun , Zhou Jian
Published: December 2020

A thermal multiphase lattice Boltzmann (LB) model is used to study the behavior of droplet impact on hot surface and the relevant heat transfer properties. After validating the correctness of the codes through the D
2 law, the simulations of intrinsic contact angle and the temperature-dependent surface tension are performed. The LB model is then used to simulate the droplet impact on smooth and micro-hole heated surface. On the smooth surface, the impinging droplet is reluctant to rebound, unless the intrinsic wettability of the solid surface is fairly good. On the micro-hole surface, however, the micro-holes provide favorable sites for generating a high-pressure vapor cushion underneath the impinging droplet, which thereby facilitates the continuous droplet rebound. For the continuously rebounding droplet. The time evolution of volume and temperature display obvious oscillations. The achievable height of the rebounding droplet increases as the intrinsic wettability of the solid surface becomes better, and the maximum transient heat flux is found to be directly proportional to the droplet rebounding height. Within a certain time interval, the continuous rebounding behavior of the droplet is favorable for enhancing the total heat quantity/heat transfer efficiency, and the influence of intrinsic wettability on the total heat during droplet impingement is greater than that of the superheat. The LB simulations not only present different states of droplets on hot surfaces, but also guide the design of the micro-hole surface with desirable heat transfer properties.
A 532 nm molecular iodine optical frequency standard based on modulation transfer spectroscopy*
Authors: Cheng Feihu , Jin Ning , Zhang Fenglei , Li Hui , Du Yuanbo , Zhang Jie , Deng Ke , Lu Zehuang
Published: December 2020

We report construction of an iodine-stabilized laser frequency standard at 532 nm based on modulation transfer spectroscopy (MTS) technology with good reproducibility. A frequency stability of 2.5 × 10−14 at 1 s averaging time is achieved, and the frequency reproducibility has a relative uncertainty of 3.5 × 10−13, demonstrating the great stability of our setup. The systematic uncertainty of the iodine-stabilized laser frequency standard is evaluated, especially the contribution of the residual amplitude modulation (RAM). The contribution of the RAM in MTS cannot be evaluated directly. To solve this problem, we theoretically deduce the MTS signal with RAM under large modulation depth, and prove that the non-symmetric shape of the MTS signal is directly related to the MTS effect. The non-symmetric shape factor r can be calibrated with a frequency comb, and in real experiments, this r value can be obtained by least-squares fitting of the MTS signal, from which we can infer the RAMinduced frequency shift. The full frequency uncertainty is evaluated to be 5.3 kHz (corresponding to a relative frequency uncertainty of 9.4 × 10−12). The corrected transition frequency has a difference from the BIPM-recommended value of 2 kHz, which is within 1 σ uncertainty, proving the validity of our evaluation.
Electron transfer properties of double quantum dot system in a fluctuating environment*
Authors: Jiang Lujing , Lan Kang , Lin Zhenyu , Zhang Yanhui
Published: December 2020

Using the innovative method of the additional Bloch vector, the electron transfer properties of a double quantum dot (DQD) system measured by a quantum point contact (QPC) in a fluctuating environment are investigated. The results show that the environmental noises in transverse and longitudinal directions play different roles in the dynamical evolution of the open quantum systems. Considering the DQD with symmetric energy level, the Fano factor exhibits a slight peak with the increase of transverse noise amplitude σ
T, which provides a basis for distinguishing dynamical phenomena caused by different directional fluctuation noises in symmetric DQD structures by studying the detector output. In the case of asymmetric DQD, the dependence of a detector current involving the level displacement is distinct when increasing the transverse noise damping coefficient τ
T and the longitudinal noise damping coefficient τε
respectively. Meanwhile, the transverse noise damping coefficient τ
T could significantly reduce the Fano factor and enhance the stability of the quantum system compared with the longitudinal one. The Fano factors with stable values as the enhancement of noise amplitudes show different external influences from the detector measurement, and provide a numerical reference for adjusting the noise amplitudes in both transverse and longitudinal directions appropriately in a microscopic experimental process to offset the decoherence effect caused by the measurements. Finally, the research of average waiting time provides unique insights to the development of single electron transfer theory in the short-time limit.
High efficiency and broad bandwidth terahertz vortex beam generation based on ultra-thin transmission Pancharatnam–Berry metasurfaces*
Authors: Li Wenyu , Zhao Guozhong , Meng Tianhua , Sun Ran , Guo Jiaoyan
Published: December 2020

The terahertz (THz) vortex beam generators are designed and theoretically investigated based on single-layer ultra-thin transmission metasurfaces. Noncontinuous phase changes of metasurfaces are obtained by utilizing Pancharatnam–Berry phase elements, which possess different rotation angles and are arranged on two concentric rings centered on the origin. The circularly polarized incident THz beam could be turned into a cross-polarization transmission wave, and the orbital angular momentum (OAM) varies in value by lℏ. The l values change from ± 1 to ± 5, and the maximal cross-polarization conversion efficiency that could be achieved is 23%, which nearly reaches the theoretical limit of a single-layer structure. The frequency range of the designed vortex generator is from 1.2 THz to 1.9 THz, and the generated THz vortex beam could keep a high fidelity in the operating bandwidth. The propagation behavior of the emerged THz vortex beam is analyzed in detail. Our work offers a novel way of designing ultra-thin and single-layer vortex beam generators, which have low process complexity, high conversion efficiency and broad bandwidth.
Impact mechanism of gas temperature in metal powder production via gas atomization*
Authors: Wang Peng , Li Jing , Wang Xin , Du Bo-Rui , Shen Shi-Yuan , Ge Xue-Yuan , Wang Miao-Hui
Published: December 2020

This paper aims at studying the influence mechanism of gas temperatures (300 K, 400 K, 500 K, and 600 K) on gas atomization by simulating the integral atomization process of the close-coupled nozzle in vacuum induction gas atomization (VIGA). The primary atomization is simulated by the volume of fluid (VOF) approach, and the second atomization is studied by the discrete phase model (DPM) combined with the instability breakage model. The results show that, at an increased gas temperature, the influences of gas–liquid contact angle and gas temperature in the recirculation zone on the primary atomization are virtually negligible. However, increasing the gas temperature will increase the gas–liquid relative velocity near the recirculation zone and decrease the melt film thickness, which are the main reasons for the reduced mass median diameter (MMD, d
50) of primary atomized droplets. During the secondary atomization, increasing the gas temperature from 300 K to 600 K results in an increase in the droplet dispersion angle, which is beneficial to the formation of spherical metal powder. In addition, increasing the gas temperature, the positive effect of gas–liquid relative velocity increase on droplets refinement overweighs the negative influence of the GMR decrease, resulting in the reduced MMD and diameter distribution interval. From the analysis of the atomization mechanism, the increase in atomization efficiency caused by increasing the temperature of the atomizing gas, including primary atomization and secondary atomization, is mainly due to the increase in the gas drag force difference between the inner and outer sides of the annular liquid film.
Cluster mean-field study of spinor Bose–Hubbard ladder: Ground-state phase diagram and many-body population dynamics*
Authors: Zhang Li , Liu Wenjie , Huang Jiahao , Lee Chaohong
Published: December 2020

We present a cluster mean-field study for ground-state phase diagram and many-body dynamics of spin-1 bosons confined in a two-chain Bose–Hubbard ladder (BHL). For unbiased BHL, we find superfluid (SF) phase and integer filling Mott insulator (IntMI) phase. For biased BHL, in addition to the SF and IntMI phases, there appears half-integer filling Mott insulator (HIntMI) phase. The phase transition between the SF and IntMI phases can be first order at a part of phase boundaries, while the phase transition between the SF and HIntMI phases is always second order. By tuning the bias energy, we report on the change of the nature of SF–MI phase transitions. Furthermore, we study the effect of the spin-dependent interaction on the many-body population dynamics. The spin-dependent interaction can lead to rich dynamical behaviors, but does not influence the particle transfer efficiency. Our results indicate a way to tune the nature of the SF–MI phase transition and open a new avenue to study the many-body dynamics of spinor bosons in optical lattices.
DFT study of solvation of Li+/Na+ in fluoroethylene carbonate/vinylene carbonate/ethylene sulfite solvents for lithium/sodium-based battery*
Authors: Liu Qi , Tan Guoqiang , Wu Feng , Mu Daobin , Wu Borong
Published: December 2020

Choosing suitable solvent is the key technology for the electrochemical performance of energy storage device. Among them, vinylene carbonate (VC), fluoroethylene carbonate (FEC), and ethylene sulfite (ES) are the potential organic electrolyte solvents for lithium/sodium battery. However, the quantitative relation and the specific mechanism of these solvents are currently unclear. In this work, density functional theory (DFT) method is employed to study the lithium/sodium ion solvation in solvents of VC, ES, and FEC. We first find that 4VC-Li+, 4VC-Na+, 4ES-Li+, 4ES-Na+, 4FEC-Li+, and 4FEC-Na+ are the maximum thermodynamic stable solvation complexes. Besides, it is indicated that the innermost solvation shells are consisted of 5VC-Li+/Na+, 5ES-Li+/Na+, and 5FEC-Li+/Na+. It is also indicated that the Li+ solvation complexes are more stable than Na+ complexes. Moreover, infrared and Raman spectrum analysis indicates that the stretching vibration of O = C peak evidently shifts to high frequency with the Li+/Na+ concentration reducing in nVC-Li+/Na+ and nFEC-Li+/Na+ solvation complexes, and the O = C vibration peak frequency in Na+ solvation complexes is higher than that of Li+ complexes. The S = O stretching vibration in nES-Li+/Na+ solvation complexes moves to high frequency with the decrease of the Li+/Na+ concentration, the S = O vibration in nES-Na+ is higher than that in nES-Li+. The study is meaningful for the design of new-type Li/Na battery electrolytes.
Suppression of ice nucleation in supercooled water under temperature gradients
Authors: Wang Li-Ping , Kong Wei-Liang , Bian Pei-Xiang , Wang Fu-Xin , Liu Hong
Published: December 2020

Understanding the behaviours of ice nucleation in non-isothermal conditions is of great importance for the preparation and retention of supercooled water. Here ice nucleation in supercooled water under temperature gradients is analyzed thermodynamically based on classical nucleation theory (CNT). Given that the free energy barrier for nucleation is dependent on temperature, different from a uniform temperature usually used in CNT, an assumption of linear temperature distribution in the ice nucleus was made and taken into consideration in analysis. The critical radius of the ice nucleus for nucleation and the corresponding nucleation model in the presence of a temperature gradient were obtained. It is observed that the critical radius is determined not only by the degree of supercooling, the only dependence in CNT, but also by the temperature gradient and even the Young’s contact angle. Effects of temperature gradient on the change in free energy, critical radius, nucleation barrier and nucleation rate with different contact angles and degrees of supercooling are illustrated successively. The results show that a temperature gradient will increase the nucleation barrier and decrease the nucleation rate, particularly in the cases of large contact angle and low degree of supercooling. In addition, there is a critical temperature gradient for a given degree of supercooling and contact angle, at the higher of which the nucleation can be suppressed completely.
An approach to gas sensors based on tunable diode laser incomplete saturated absorption spectra*
Authors: Nie Wei , Xu Zhen-Yu , Kan Rui-Feng , Dong Mei-Rong , Lu Ji-Dong
Published: December 2020

A spectral profile reconstruction method that can be applied to incomplete saturated-absorption spectra is proposed and demonstrated. Through simulation and theoretical calculation, it is proved that compared with the traditional whole-profile fitting method, this new method can increase the concentration detection upper limit of a single absorption line by about 8.7 times. High-concentration water vapor is measured using TDLAS technology, the total water vapor pressure and the self-broadened half-width coefficient of the spectrum were simultaneously measured from incomplete saturated-absorption spectra and compared with high-precision pressure sensors and the HITRAN databases. Their maximum relative deviations were about 4.63% and 9.10%, respectively. These results show that the spectral profile reconstruction method has great application potential for expanding the dynamic range of single-line measurements to higher concentrations, especially for in-situ online measurements under complex conditions, such as over large temperature and concentration dynamic ranges.
Modulation of the second-harmonic generation in MoS2 by graphene covering*
Authors: Wu Chunchun , Shang Nianze , Zhao Zixun , Zhang Zhihong , Liang Jing , Liu Chang , Zuo Yonggang , Ding Mingchao , Wang Jinhuan , Hong Hao , Xiong Jie , Liu Kaihui
Published: December 2020

Nonlinear optical frequency mixing, which describes new frequencies generation by exciting nonlinear materials with intense light field, has drawn vast interests in the field of photonic devices, material characterization, and optical imaging. Investigating and manipulating the nonlinear optical response of target materials lead us to reveal hidden physics and develop applications in optical devices. Here, we report the realization of facile manipulation of nonlinear optical responses in the example system of MoS2 monolayer by van der Waals interfacial engineering. We found that, the interfacing of monolayer graphene will weaken the exciton oscillator strength in MoS2 monolayer and correspondingly suppress the second harmonic generation (SHG) intensity to 30% under band-gap resonance excitation. While with off-resonance excitation, the SHG intensity would enhance up to 130%, which is conjectured to be induced by the interlayer excitation between MoS2 and graphene. Our investigation provides an effective method for controlling nonlinear optical properties of two-dimensional materials and therefore facilitates their future applications in optoelectronic and photonic devices.
The implications of future climate change on the blue water footprint of hydropower in the contiguous US
*
Authors: Zhao Gang , Gao Huilin , Kao Shih-Chieh
Published: December 2020

As the largest renewable energy source, hydropower is essential to the sustainability of the global energy market. However, a considerable amount of water can be lost in the form of evaporation from the associated multipurpose reservoirs, and hence enlarge the blue water footprint (BWF) of hydropower in a warming climate. To facilitate the sustainable management of both water and energy resources under the impact of climate change in the contiguous United States (CONUS), the BWF values of 143 major multipurpose reservoirs were evaluated during the historical period (1985–2014) and two future periods (2020–2049 and 2070–2099). The historical reservoir evaporation loss was calculated using the Landsat-based reservoir surface area and a new evaporation rate algorithm that considers the heat storage effect. Future projections of runoff availability, hydropower generation, and reservoir evaporation were estimated based on the downscaled climate model ensemble from phase 5 of the Coupled Model Intercomparison Project. It was found that the BWF for the CONUS is highly spatially heterogeneous, with an average value of 26.2 m3 MWh−1 in the historical period. In the future, the BWF values are projected to increase under both Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios. This is especially noticeable under RCP 8.5, which has an average BWF value of 30.2 m3 MWh−1 for 2070–2099 (increasing by 15.3% from 26.2 m3 MWh−1). The uncertainty ranges increase even more, from 3.4 m3 MWh−1 during 2020–2049 to 5.7 m3 MWh−1 during 2070–2099. These findings can benefit water and energy resources management in identifying suitable environmental, economic, operational, and investment strategies for multipurpose reservoirs in a changing environment.
An analytic approach to maximize entropy for computing equilibrium densities of k-mers on linear chains
Authors: Ávila A I , González-Flores M I , Lebrecht W
Published: December 2020

The irreversible adsorption of polyatomic (or k-mers) on linear chains is related to phenomena such as the adsorption of colloids, long molecules, and proteins on solid substrates. This process generates jammed or blocked final states. In the case of k = 2, the binomial coefficient computes the number of final states. By the canonical ensemble, the Boltzmann–Gibbs–Shannon entropy function is obtained by using Stirling’s approximation, and its equilibrium density ρ
eq,2 is its maximum at the thermodynamic limit with value ρ
eq,2 ≈ 0.822 991 17. Moreover, since at the same energy we have several possible configurations, we obtain the state probability density. Maximizing the entropy, it converges to a Gaussian distribution

N

(

ρ

e
q
,
2

,

σ

e
q
,
2

2

)

as L → ∞.

In this article, we generalize this analysis to k > 2 to maximize the entropy and to get the equilibrium densities ρ
eq,k
. We first develop a complete combinatorial analysis to get the generalized recurrence formula (GRF) for counting all blocked configuration states on a chain of length L with fixed k, which corresponds to a generalized truncated Fibonacci sequence. The configuration states for allocating N k-mers is related with the general binomial coefficient

N
+
1
,
k

m

. Since Stirling’s approximation cannot be used for GRF, we numerically compute the state probability density and approximate ρ
eq,k
and σ
eq,k
for large k-mers with high precision for k-mers up to k = 1, 000, 000. We highlight that ρ
eq,k
decreases from k = 2, …, 8 reaching a minimum at k = 9 and then increases with an asymptotic value ρ
eq,∞ = 0.9285685. We compared with jamming densities obtained by RSA and at k ≈ 16, both curves intersect and ergodicity is not broken since ρ
jam,k
≈ ρ
eq,k
. In the case of

σ

e
q
,
k

2

, it grows similarly with asymptotic value

σ

e
q
,
∞

2

=
0.862

9597

. Since the similar behavior for large values, we found the limit relationship

σ

e
q
,
k

2

=

ρ

e
q
,
k

2

as L → ∞ for any k. Finally, as k → ∞, we get the Gaussian distribution for the continuous blocked irreversible adsorption or equivalent to the irreversible blocked car parking problem.
Carbon Dynamics Projection for the Quercus petraea and Robinia pseudoacacia Species - Case Study
Authors: Norbert Bara , Anda Rotaru , Lucian Laslo , Monica Matei , Madalina Boboc , Valentina Coman , Madalina Voicu , Natalia Enache , György Deak
Published: December 2020

Atmospheric CO2 is rising rapidly. As forests cover some 43% of the Earth’s surface, they are considered to be the largest terrestrial carbon sink on Planet Earth. Within this study, calculations of the most abundant tree species were conducted in the study area, which is situated in the Eastern region of Romania. Thus, the forest carbon balance for the Oak (Quercus petraea) and Black Locust (Robinia pseudoacacia) species were projected for the period of 2015 - 2040. Data from management plans were used and analyzed using a forest model that is projecting forest resource development on regional up to European scale, known as The European Forest Information SCENario Model - EFISCEN. This study is aiming to point out the potential of the Oak and Black Locust forests to store carbon within the aforementioned period considering that the same management practices will be applied. The results of the simulation show that the forests accumulate CO2 over time and also their magnitude can be observed. Conclusions can be drawn from the comparative analysis of the input data and the simulation results, considering the limitation of the used data in terms of their precision.
A Review of PM10 Concentrations Modelling in Malaysia
Authors: Nur Shaziayani Wan , Zia Ul-Saufie Ahmad , Libasin Zuraira , Norsyiha Ahmad Shukri Fuziatul , Sarimah Syed Abdullah Sharifah , Mohamed Noor Norazian
Published: December 2020

The purpose of predictive modelling is to predict the variable of interest with reasonable precision, and often to assess the contribution of the independent variables to the dependent variable. In this paper, all of the works examined are aimed at predicting concentrations of outdoor PM10 concentrations. The vast majority of the works reported used almost exclusively predictors of the meteorological and source emissions. However, the use of the Hybrid model in predicting PM10 concentrations is still not widely used in Malaysia.
Effect of Additives on the Ash Element from Combustion of Palm Fiber and Shell
Authors: NorRuwaida J , Dewika M , Shahidana S , Rashid M , Halim Md Ali Abd , Khairunnisa M P , Ammar M R , Zahiruddin S , Sara Y Y
Published: December 2020

Palm fibre and shell (F&S) are commonly used in the combustion process to produce steam and electricity in palm oil mills in Malaysia. Unfortunately, the combustion process releases various types of elements that tends to react with each other contributing to operational and environmental issues. Thus, this motivated, a study to evaluate the concentration of the elements such as C, O, Si, K, and Al in the ash with the presence of two combustion additive which are Kaolin and PreKotTM. The study was performed by simulating the industrial combustion in a laboratory-scale fluidised-bed reactor with addition of the additives at 8% ratio from the 40 g total weight of each sample at 800°C with the supply of 50% excess air at 1.24 L/min air flow. The ash residue were investigated for elemental composition on the ash surface. Interestingly, the study showed that the concentration of the element on the ash surface increased with the addition of additives especially at a 50% ratio of Kaolin and PreKotTM. The higher concentration of the element on the ash surface indicates the reduction of fine particulate. Hence, the study revealed that addition of Kaolin & PrekotTM in combustion process has a promising future not only within palm oil industry but also other industry.
Experimental Determination of Carbon Dioxide Flux in Soil and Correlation with Dependent Parameters
Authors: Madalina Voicu , Valentina Coman , Natalia Enache , Lucian Laslo , Monica Matei , Anda Rotaru , Norbert Bara , Madalina Boboc , Silvius Stanciu , György Deak
Published: December 2020

Carbon dioxide is one of the greenhouse gases responsible for the effects of climate change. The soil respiration process is an important component of the carbon circuit in nature, through which carbon dioxide returns to the atmosphere. The concentration of CO2 in the atmosphere is directly influenced by any change of carbon flow produced in soil, as the latter is the largest carbon sink in terrestrial ecosystems. The objective of this paper is to present the experimental results obtained using CO2 flow determination with portable GHG analyzer with closed static chamber, and the relation and influence of the main pedoclimatic parameters, namely temperature and humidity. Future research directions will consider the development of a plan to monitor CO2 flow from the soil, for different types of land use, in different climatic conditions. During one month of data collection, has been found that soil CO2 efflux was influenced by soil moisture and soil temperature. Also, the processed data showed how soil respiration rates were dependent on soil moisture.
Enhanced Chlorinated very Short-Lived Substances in South East Asia: Potential Source Regions and Source Types
Authors: Mohd Hanif Norfazrin , Reeves Claire E. , Oram David E. , Ashfold Matthew J. , Panagi Marios , Fleming Zoe L. , Gooch Lauren J. , Laube Johannes C. , Abu Samah Azizan , Amin Abdullah Ahmad , Sturges William T.
Published: December 2020

Enhancements of the mixing ratios of short-lived halogenated gases were observed in air samples collected at Bachok Marine Research Station (BMRS), Peninsular Malaysia during Northern Hemisphere winters in 2013/2014 and 2015/2016. This study investigates the potential source regions and source types that influenced the variability in chlorinated very short-lived substances (Cl-VSLS) [dichloromethane, 1,2-dichloroethane, trichloromethane, tetrachloroethene] and methyl halides [methyl chloride and methyl bromide]. The UK Met Office’s Numerical Atmospheric Modelling Environment (NAME) dispersion model, was used for tracking the origin of air masses arriving at BMRS. For the purpose of identifying possible sources of these compounds, carbon monoxide (CO) emission data taken from the Representative Concentration Pathway 8.5 were used along with NAME footprints to calculate modelled CO mixing ratios. A correlation analysis between the mixing ratios of measured compounds and the modelled CO from various emission sectors was perform to assess the extent to which emission sectors might be related to the mixing ratios of halogenated gases. The results show that the events of higher mixing ratios were associated with air masses, especially from East China. During the 2013/2014 campaign, the modelled CO from industrial, solvents and agriculture (waste burning on fields) were significantly correlated with the mixing ratios of Cl-VSLS (R > 0.7) and methyl halides (R > 0.40). During the 2015/2016 campaign, the strength of these correlations reduced for Cl-VSLS (R > 0.5) and with no significant correlations for methyl halides. Instead, mixing ratios of methyl halides were correlated (R=0.4) with modelled CO from forest burning. This work provides evidence that East and South East Asia act as important sources of halogenated gases. This is of significant given the proximity of these regions to prevalent deep convection which can rapidly transport these halogencontaining gases into the stratosphere and impact the ozone layer.
Adsorption of Volatile Organic Compound (VOCs) Over Formulated Prechar
Authors: NorRuwaida J , Haslina H , Rashid M , Najihah A R , Masdiana N , Dewika M , Ammar M R , Noor N M , Afiq Daniel A
Published: December 2020

Volatile organic compounds (VOCs) are being released as a result from incomplete combustion processes in the industry. Dry sorbent injection of activated carbon on fabric filters is one of the methods that are being used for VOCs removal in the flue gas. Dry sorbents act as filter aids to enhance the adsorption efficiency besides to overcome wear and tear problems that occurred during filtration. Biochar which is grinded bamboo charcoal was combined with PreKotTM, a pre-coating agent as a filter aids formulation. This study introduced a newly two filter aids formulation known as PreChar10:90 and PreChar20:80 besides biochar as raw material. These three samples were initially evaluated through physical properties of moisture content and surface area before being tested on adsorption tests. PreChar20:80 and biochar presented a good sign with lower moisture content 3.306% and 3.417% respectively. Besides, surface area of both PreChar formulations was consecutively low compared to biochar due to PreKotTM existence as the PreKotTM’s size is much larger. Large particle size of the filter aids results in low surface area available. In the adsorption test, flow rates were manipulated to be 0.1 L/min, 0.3 L/min and 0.5 L/min during the adsorption process. Filter aids formulation promises a huge amount of adsorption capacity by having longer period breakthrough points at which filter aids start to be saturated. It can be concluded that PreChar20:80 results in the highest adsorption capacity at all three different flow rates with 0.437 mg/g, 2.353 mg/g and 11.031 mg/g respectively. In this regard, PreChar20:80 has the potential to be an alternative material for activated carbon in the fabric filter application.
Multifractal Properties of Temporal Rainfall Series in Peninsular Malaysia
Authors: Mariam Saad Siti , Ismail Noriszura
Published: December 2020

Studies on the investigation of scale-invariance of rainfall are still in the early development stage in the humid tropical regions. In order to further enhance understanding of the rainfall variability across a range of temporal scales in these regions, this study aims to investigate and characterize rainfall in a multifractal framework from areas in Peninsular Malaysia. It is done by studying the scaling of the statistical properties of rainfall. Data set consisting of 15 min rainfall observations from 56 rain gauge stations were adopted and the stations were grouped into four regions to identify the possibility that the multifractal properties of rainfall could depend on the geographical locations and local climatology. The results show that the temporal structure of rainfall in Peninsular Malaysia displays a multifractal behaviour for scales ranging from 15 min to about 3 days. The multifractal parameters that described the scaling properties of rainfall in terms of intermittency and multifractality revealed to be different for each region in the peninsula, particularly between the west and east coasts. The rainfall process for east coast was characterized by less intermittent rain with the rainfall fluctuations displaying a strong degree of multifractality. While for the west coast which consists of northwest, west and southwest regions, they exhibited a similar distribution of rainfall occurrences which is very intermittent and unsmoothed. Rainfall fluctuations, however, were spikier in northwest regions than in the west and southwest regions.
Quantification Study for Construction Waste Generation in Housing Project
Authors: Hafizan Hassan Siti , Abdul Aziz Hamidi , Samsudin Abdul Hamid Mohd , Zakariah Zulfairul , Ainun Musir Adhilla
Published: December 2020

One of the main contributors to the waste generated in the Malaysian construction industry is housing projects. The construction waste has increased over years, creating environmental problems and profit loss to contractors. Limited data are available to date in Malaysia, especially in terms of sources, types and quantity. The aim of this study is to explore the causes and contributory factors that cause waste generation in selected housing project followed by quantification of common waste generated at sites. Site observation and interviews with labors and site management was conducted in determining the waste sources and waste management practices. Management and workers were the main causes of waste generated in this study.
Immobilization of Bacillus sphaericus with Palm Oil Fuel Ash for Self-healing in the Mortar
Authors: Azan Tajarudin Husnul , Santiagoo Ragunathan , Gomesh Nair , Daud Zawawi , Azmi Megat Johari Megat , Hisham Abu Bakar Badorul , Wahdah Djuanda Rawahah
Published: December 2020

Crack in concrete or mortar provides preferential accesses for permeation of liquids and gasses which results in degradation of concrete or mortar and structural failure. Basically, this study has used immobilizedBacillus sphaericus(B.sphaericus) with palm oil fuel ash as self-healing agent in the mortar. The strength of the mortar was improved throughprecipitation of calcium carbonate byB.sphaericuscausing stronger structure due to the binding effect of calcium silicate (C-S-H) gel produced from the pozzolanic reaction. Both self-healing agentswere most likely increased the performance of self-healing in the mortar. In the first phase of this study, the immobilization of both self-healing agentswas studied. This was then followed by embedment of immobilizedB.sphaericuswith POFA into mortar mixture and the effect of different mortar proportion on flow table diameter, compressive strength, microstructural and atomic percentage. It was found that samples containing bio-based self-healing agent recorded the highest compressive strength of 20.95 MPa. The micrograph of SEM and EDX analysis showed that self-healing occurred when secondary C-S-H gel and calcium carbonate present in particular sample. From the result obtained, embedment of the immobilizedB.sphaericuswith POFA into mortar mixture could solve the crack issue.