bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrafast dynamics of the low frequency shear phonon in 1T′-MoTe2
Authors: Fukuda Takumi , Makino Kotaro , Saito Yuta , Fons Paul , Kolobov Alexander V. , Ueno Keiji , Hase Muneaki
Published: March 2020

We report on the dynamics of coherent phonons in semimetal 1T′-MoTe2 using femtosecond pump-probe spectroscopy. On an ultrafast sub-picosecond timescale at room temperature, a low frequency and long-lifetime shear phonon mode was observed at 0.39 THz, which was previously reported in the form of a characteristic phonon only in the low temperature Td−MoTe2 phase. Unlike the other optical phonon modes, the shear phonon mode was found to strongly couple with photoexcited carriers. Moreover, the amplitude of the shear mode surprisingly decreased with increasing excitation density, a phenomenon that can be attributed to be a consequence of the lattice temperature increasing after excitation. These results provide useful physical information on ultrafast lattice symmetry switching between the normal semimetal 1T′ and the lattice inversion symmetry breaking Type-II Weyl semimetal Td phases.
Electrically induced droplet ejection dynamics under shear flow
Authors: Raman K. Ashoke , Birgersson Erik , Sui Yi , Fisher Adrian
Published: March 2020

Droplet nucleation, condensation, and transport is a ubiquitous phenomenon observed in various industrial applications involving power generation and energy conversion to enhance heat transfer. Recent studies have shown that electrowetting (EW) has emerged as a new tool to enhance pool boiling heat transfer. In these applications involving heat transfer through pool boiling, the interplay between the incoming air and an EW-induced jumping droplet is instrumental in determining the overall heat transfer enhancement. This study investigates the transport dynamics of EW-induced droplet ejection in shear flow. A high-density ratio based lattice Boltzmann method is employed to model the ejection dynamics, and a geometry-based contact angle formulation is used to capture the three-phase contact line. We observe a characteristic head vortex at the leading end of the droplet, the strength of which increases with an increase in the shear rate. The droplet angle of flight, aspect ratio, and surface energy are found to increase with an increase in the applied voltage. Variations in pulse width induce a phase shift in the temporal evolution of the angle of flight and aspect ratio. Due to an increase in drag forces, the droplet traverses a larger streamwise distance at higher gas densities.
A physics-based model of a dynamic tangential contact system of lap joints with non-Gaussian rough surfaces based on a new Iwan solution
Authors: Li Wei , Zhan Wanglong , Huang Ping
Published: March 2020

This paper aims to propose a tangential contact model of a lap joint interface with non-Gaussian surfaces. Relying on the full-stick contact condition, the elastic–plastic deformation of a single asperity and the penetration-dependent friction coefficient are considered in this model. The Johnson system is utilized to generate non-Gaussian asperity height distributions. Furthermore, the physical asperity model and the phenomenological Iwan model are combined to obtain a continuous and convergent Iwan solution by the dimensional analysis method. The initial tangential stiffness, the tangential force required for gross slip, and the slip index of lap joints reveal the hysteresis loop shape, describing the tangential response completely and uniquely, and the first two parameters are proved to own statistical characteristics. Next, the effects of topography parameters on the initial tangential stiffness, the tangential force/displacement required for gross slip, and the slip index are analyzed. Comparisons among the proposed model, the published models, and the published experimental results have also been made. The proposed model is shown to be consistent with the experimental results when the tangential load is insufficient to cause gross slip, while an error is produced when gross slip happens. Additionally, the error could be reduced in the calibrated model.
Sexual health practices of 16 to 19 year olds in New Zealand: an exploratory study
Authors: Ellis Sonja J. , Aitken Robyn
Published: March 2020

ABSTRACT
INTRODUCTIONNew Zealand sexual health surveillance data suggest that young people aged 15–19 years are at considerable risk of contracting sexually transmitted infections. Although there is an established body of international research around sexual behaviours and sexual health practices among teenagers, there is a dearth of local research focusing on this age group.
AIMThe aim of this study was to explore the sexual repertoires and sexual health practices among teenagers in New Zealand with a view to better understanding levels of risk in this age group.
METHODSThis study comprised a cross-sectional online survey designed to ask questions about sexual behaviours. A convenience sample of young people (n=52) aged 16–19 years living in New Zealand completed the survey.
RESULTSMost participants (71.2%) were sexually active, reporting engagement in a range of sexual practices. The most commonly reported sexual behaviours were penis-in-vagina sex (86.5%) and oral sex with a person-with-a-penis (81.1%). Infrequent and inconsistent use of barrier protection across all types of sexual behaviour was also reported.
DISCUSSIONThe findings of this study highlight the importance of ensuring that young people have access to sexual health education that routinely includes health information and advice addressing the full range of sexual practices, regardless of the identity classifications they may use, or that may be attributed to them.
TDP-43 α-helical structure tunes liquid–liquid phase separation and function
Authors: Conicella Alexander E. , Dignon Gregory L. , Zerze Gül H. , Schmidt Hermann Broder , D’Ordine Alexandra M. , Kim Young C. , Rohatgi Rajat , Ayala Yuna M. , Mittal Jeetain , Fawzi Nicolas L.
Published: March 2020

Liquid–liquid phase separation (LLPS) is involved in the formation of membraneless organelles (MLOs) associated with RNA processing. The RNA-binding protein TDP-43 is present in several MLOs, undergoes LLPS, and has been linked to the pathogenesis of amyotrophic lateral sclerosis (ALS). While some ALS-associated mutations in TDP-43 disrupt self-interaction and function, here we show that designed single mutations can enhance TDP-43 assembly and function via modulating helical structure. Using molecular simulation and NMR spectroscopy, we observe large structural changes upon dimerization of TDP-43. Two conserved glycine residues (G335 and G338) are potent inhibitors of helical extension and helix–helix interaction, which are removed in part by variants at these positions, including the ALS-associated G335D. Substitution to helix-enhancing alanine at either of these positions dramatically enhances phase separation in vitro and decreases fluidity of phase-separated TDP-43 reporter compartments in cells. Furthermore, G335A increases TDP-43 splicing function in a minigene assay. Therefore, the TDP-43 helical region serves as a short but uniquely tunable module where application of biophysical principles can precisely control assembly and function in cellular and synthetic biology applications of LLPS.
Visualizing the translation and packaging of HIV-1 full-length RNA
Authors: Chen Jianbo , Liu Yang , Wu Bin , Nikolaitchik Olga A. , Mohan Preeti R. , Chen Jiji , Pathak Vinay K. , Hu Wei-Shau
Published: March 2020

Significance

The major viral components of HIV-1 virions are full-length RNA (HIV-1 RNA) and its translation products. Packaged HIV-1 RNA carries viral genetic information, and its translation products Gag and Gag-Pol constitute the virus structure and all the viral enzymes. Using live-cell imaging and biochemical approaches, we found that half of the HIV-1 RNA population is actively translated; cytoplasmic translating and nontranslating RNAs are well mixed, indicating Gag is not synthesized in specialized compartments. Both translating and nontranslating RNAs move dynamically and can reach the major virus assembly site. However, Gag packages nontranslating RNA; thus, although HIV-1 RNA serves two functions, each molecule performs only one function at a time. These studies provide insight into HIV-1 gene expression and virus assembly.
Assessing thyroid cancer risk using polygenic risk scores
Authors: Liyanarachchi Sandya , Gudmundsson Julius , Ferkingstad Egil , He Huiling , Jonasson Jon G. , Tragante Vinicius , Asselbergs Folkert W. , Xu Li , Kiemeney Lambertus A. , Netea-Maier Romana T. , Mayordomo Jose I. , Plantinga Theo S. , Hjartarson Hannes , Hrafnkelsson Jon , Sturgis Erich M. , Brock Pamela , Nabhan Fadi , Thorleifsson Gudmar , Ringel Matthew D. , Stefansson Kari , de la Chapelle Albert
Published: March 2020

Genome-wide association studies (GWASs) have identified at least 10 single-nucleotide polymorphisms (SNPs) associated with papillary thyroid cancer (PTC) risk. Most of these SNPs are common variants with small to moderate effect sizes. Here we assessed the combined genetic effects of these variants on PTC risk by using summarized GWAS results to build polygenic risk score (PRS) models in three PTC study groups from Ohio (1,544 patients and 1,593 controls), Iceland (723 patients and 129,556 controls), and the United Kingdom (534 patients and 407,945 controls). A PRS based on the 10 established PTC SNPs showed a stronger predictive power compared with the clinical factors model, with a minimum increase of area under the receiver-operating curve of 5.4 percentage points (
P
≤ 1.0 × 10
−9
). Adding an extended PRS based on 592,475 common variants did not significantly improve the prediction power compared with the 10-SNP model, suggesting that most of the remaining undiscovered genetic risk in thyroid cancer is due to rare, moderate- to high-penetrance variants rather than to common low-penetrance variants. Based on the 10-SNP PRS, individuals in the top decile group of PRSs have a close to sevenfold greater risk (95% CI, 5.4–8.8) compared with the bottom decile group. In conclusion, PRSs based on a small number of common germline variants emphasize the importance of heritable low-penetrance markers in PTC.
Engagement and reviewers’ reports on submissions to academic
journals
Authors: Paltridge Brian
Published: March 2020

This paper examines the use of engagement strategies in
reviewers’ reports on submissions to academic journals. The data examined are
reviewers’ reports on submissions to the journal English for Specific
Purposes. The study found that the reviewers used directives as
their main engagement strategy. These directives, however, were often indirect
or hedged, making it difficult for writers who are new to the peer review
process to know how to respond to them. A further engagement strategy that
reviewers employed was the use of reader pronouns through which they established
an interpersonal relationship with authors at the same time as they delivered
‘bad news’ to them. These matters are important to highlight in the teaching of
writing for research publication purposes so that beginning authors can better
understand reviewers’ reports, learn how to respond to them and, as a result,
increase their chances of getting published.
Towards the meV limit of the effective neutrino mass in neutrinoless double-beta decays *
Authors: Cao Jun , Huang Guo-yuan , Li Yu-Feng , Wang Yifang , Wen Liang-Jian , Xing Zhi-zhong , Zhao Zhen-hua , Zhou Shun
Published: March 2020

We emphasize that it is extremely important for future neutrinoless double-beta (

) decay experiments to reach the sensitivity to the effective neutrino mass

. With such a sensitivity, it is highly possible to discover the signals of

decays. If no signal is observed at this sensitivity level, then either neutrinos are Dirac particles or stringent constraints can be placed on their Majorana masses. In this paper, assuming the sensitivity of

for future

decay experiments and the precisions on neutrino oscillation parameters after the JUNO experiment, we fully explore the constrained regions of the lightest neutrino mass

and two Majorana-type CP-violating phases

. Several important conclusions in the case of normal neutrino mass ordering can be made. First, the lightest neutrino mass is severely constrained to a narrow range

, which together with the precision measurements of neutrino mass-squared differences from oscillation experiments completely determines the neutrino mass spectrum

and

. Second, one of the two Majorana CP-violating phases is limited to

, which cannot be obtained from any other realistic experiments. Third, the sum of three neutrino masses is found to be

, while the effective neutrino mass for beta decays turns out to be

. These observations clearly set up the roadmap for future non-oscillation neutrino experiments aiming to solve the fundamental problems in neutrino physics.
Analysis of the excited bottom and bottom-strange states B1(5721), B2⃰(5747), Bs1(5830), Bs2⃰(5840), BJ(5840) and BJ(5970) of the B meson family *
Authors: Yu Guo-Liang , Wang Zhi-Gang
Published: March 2020

In order to make a further confirmation of the assignments of the excited bottom and bottom-strange mesons

,

,

and

and identify possible assignments of

and

, we study the strong decay of these states with the

decay model. Our analysis supports the assignments of

and

as the

and

states, and

and

as the strange partners of

and

. Besides, we tentatively identify the recently observed

and

as the

and

states. It is noted that these conclusions need further confirmation by measurements of the decay channels

and

.
Charged pion condensation in anti-parallel electromagnetic fields and nonzero isospin density *
Authors: Chao Jingyi , Huang Mei , Radzhabov Andrey
Published: March 2020

The formation of charged pion condensate in anti-parallel electromagnetic fields and in the presence of the isospin chemical potential is studied in the two-flavor Nambu–Jona-Lasinio model. The method of Schwinger proper time is extended to explore the quantities in the off-diagonal flavor space, i.e. the charged pion. In this framework,

are treated as bound states of quarks and not as point-like charged particles. The isospin chemical potential plays the role of a trigger for charged pion condensation. We obtain the associated effective potential as a function of the strength of the electromagnetic fields and find that it contains a sextic term which possibly induces a weak first order phase transition. The dependence of pion condensation on model parameters is investigated.
High-K multi-particle bands and pairing reduction in 254No *
Authors: He Xiao-Tao , Zhao Shu-Yong , Zhang Zhen-Hua , Ren Zhong-Zhou
Published: March 2020

The multi-particle states and rotational properties of the two-particle bands in

are investigated by the cranked shell model with pairing correlations treated by the particle number conserving method. The rotational bands on top of the two-particle

and

states and the pairing reduction are studied theoretically in

for the first time. The experimental excitation energies and moments of inertia of the multi-particle states are reproduced well by the calculations. Better agreement with the data is achieved by including the high-order deformation

, which leads to enlarged

and

deformed shell gaps. An increase of

in these two-particle bands compared with the ground state band is attributed to the pairing reduction due to the Pauli blocking effect.
The kinematical and space structures of IC 2391 open cluster and moving group with Gaia-DR2
Authors: Postnikova E. S. , Elsanhoury W. H. , Sariya Devesh P. , Chupina N. V. , Vereshchagin S. V. , Jiang Ing-Guey
Published: March 2020

The kinematical parameters, spatial shape and structure of the open cluster IC 2391 and the associated stellar stream are studied here using Gaia Data Release 2 (GDR2) astrometry data. The apex positions are determined for the open cluster IC 2391 (data taken from Cantat-Gaudin et al.) and for the kinematical stream’s stars mentioned in Montes et al. employing both convergent point and AD-diagram methods. The values of apex coordinates are: (A, D)CP = (

6
.
h

17
±

0
.
h

004
,
−

6
.
°

88
±

0
.
°

381

; for cluster) and (

6
.
h

07
±

0
.
h

007

,

−

5
.
°

00
±

0
.
°

447

; stream), and (A
0, D
0) = (

6
.
h

12
±

0
.
h

004

,

−

3
.
°

4
±

0
.
°

3

; cluster) and (

6
.
h

21
±

0
.
h

007

,

−

11

.
°

895
±

0
.
°

290

; stream). The results are in good agreement with the previously calculated values. The positions of the stars in the disk and the spatial dispersion velocities are determined. The paths of cluster and associated stream are traced in the disk by orbit calculation back in time to their places of formation. A possible genetic relationship between the cluster and stream has been detected. The approximation of the spatial and kinematical shape of the stream and the cluster is made. According to this study, even though currently the cluster and stream seem to have a spatial difference in their locations, they appear to have formed in the same region of the Galactic disk.
The physical properties of galaxies with unusually high gas-phase metallicity
Authors: Chen Yong-Yun , Gu Qiu-Sheng , Ge Xue
Published: March 2020

We use 1221 galaxies with unusually high gas-phase metallicity to study their physical properties. The scope of redshift is 0.02 < z < 0.25 for these galaxies with unusually high gas-phase metallicity. Our goal is to understand the physical origins of the high gas-phase metallicity. To address this study, we select a control sample matching similar redshift and stellar mass. Our main results are as follows. (i) Compared with the control sample, the high-metallicity sample shows lower ionization parameter, higher electron density and more dust content. (ii) We also find that the high-metallicity sample has older stellar age and higher [Mgb/] ratio, which indicates that the high-metallicity sample has shorter timescale of star formation. (iii) According to the plane of HδA
vs. D
n
4000, we can see that the control sample has higher HδA
and lower D
n
4000 than the high-metallicity sample, which may imply that the control sample experiences recent star formation. (iv) There is a significant difference in gas distribution between the high-metallicity and control samples. The high-metallicity sample has lower gas fraction than control sample, which indicates that galaxies have high gas-phase metallicity probably due to their low HI gas fraction. (v) There is no significant difference between the high-metallicity and control samples in environment, which may suggest that the environment has no effect on gas-phase metallicity.
The mid-infrared variability of the SDSS optical quasars
Authors: Wang Hong-Tao , Shi Yong
Published: March 2020

Based on the Seventh Data Release (DR7) quasar catalog from the Sloan Digital Sky Survey, we investigate the variability of optical quasars in W1, W2, W3 and W4 bands of the Wide-field Infrared Survey Explorer (WISE) and the Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE). Adopting the structure function (SF) method, we calculate the SF (δ t = 1 yr) which shows no obvious correlations with the bolometric luminosity, the black hole mass and the Eddington ratio. The ensemble SFs in W1 and W2 bands show that the SF slopes are steeper than those in previous studies which may be caused by different cadence and observational epoch number. We further investigate the relation of variability amplitude σm
between mid-infrared band and optical band, but no obvious correlation is found. No correlation is found between W1–W2 and g – r color. We think that the mid-infrared emission of quasars may be smoothed out by the extended dust distribution, thus leading to no obvious correlation. For the radio-loud quasar sub-sample, we further analyze the relation between the variability amplitude in the mid-infrared band and the radio luminosity at 6 cm, but no obvious correlations are found, which indicate the mid-infrared emission contributed from the synchrotron radiation of the relativistic jet is very weak.
Periodic variation and phase analysis of grouped solar flare with sunspot activity
Authors: Deng Hui , Mei Ying , Wang Feng
Published: March 2020

Studies on the periodic variation and the phase relationship between different solar activity indicators are useful for understanding the long-term evolution of solar activity cycles. Here we report the statistical analysis of grouped solar flare (GSF) and sunspot number (SN) during the time interval from January 1965 to March 2009. We find that, (1) the significant periodicities of both GSF and SN are related to the differential rotation periodicity, the quasi-biennial oscillation (QBO), and the eleven-year Schwabe cycle (ESC), but the specific values are not absolutely identical; (2) the ESC signal of GSF lags behind that of SN with an average of 7.8 months during the considered time interval, which implies that the systematic phase delays between GSF and SN originate from the inter-solar-cycle signal. Our results may provide evidence about the storage of magnetic energy in the corona.
Interplanetary consequences and geoeffectiveness of CME associated with major solar flare from NOAA AR 12673
Authors: Soni Shirsh Lata , Gupta Radhe Shyam , Verma Pyare Lala
Published: March 2020

In this reported work, we study a major X-class flare (X9.3) that arose from NOAA Active Region (AR) 12673 on 2017 September 6, from 11:53 UT to 12:10 UT in multi-wavelength views. This event also produced a fast coronal mass ejection (CME). NOAA AR 12673 emerged at S09W30 on 2017 September 6 and grew rapidly to a large AR. On 2017 September 9, the maximum area of this AR was 1060 millionth of the solar hemisphere. The group of sunspots disappeared over the west limb of the Sun (S09W83) on September 10. It was a fast emerging flux region. The group of sunspots showed magnetic configuration category alpha-beta-gamma. We identified their earliest signatures of eruption in AIA 94 Å images with initialization and successive rapid growth from low coronal heights of hot channeled structures. On the other hand, the CME associated with this flare event triggered the intense Dst at 1AU (−142nT). We have acquired observations and analyze the reported event from the Sun’s surface, corona (source AR), interplanetary space and in-situ measurement near Earth. In addition, here we analyze the complex processes of CME-CME interaction that have contributed a significant role to make the reported event so geoeffective.
The relationship between the radio core-dominance parameter and spectral index in different classes of extragalactic radio sources (III)
Authors: Pei Zhi-Yuan , Fan Jun-Hui , Bastieri Denis , Yang Jiang-He , Xiao Hu-Bing , Yang Wen-Xin
Published: March 2020

Active galactic nuclei (AGNs) can be divided into two major classes, namely radio-loud and radio-quiet AGNs. A small subset of the radio-loud AGNs is called blazars, which are believed to be unified with Fanaroff-Riley type I and type II (FRI&II) radio galaxies. Following our previous work, we present a latest sample of 966 sources with measured radio flux densities of the core and extended components. The sample includes 83 BL Lacs, 473 flat spectrum radio quasars, 101 Seyferts, 245 galaxies, 52 FRIs&IIs and 12 unidentified sources. We then calculate the radio core-dominance parameters and spectral indices and study their relationship. Our analysis shows that the core-dominance parameters and spectral indices are quite different for different types of sources. We also confirm that the correlation between core-dominance parameter and radio spectral index extends over all the sources in a large sample presented.
A quark nova in the wake of a core-collapse supernova: a unifying model for long duration gamma-ray bursts and fast radio bursts
Authors: Ouyed Rachid , Leahy Denis , Koning Nico
Published: March 2020

By appealing to a quark nova (QN; the explosive transition of a neutron star to a quark star) in the wake of a core-collapse supernova (CCSN) explosion of a massive star, we develop a unified model for long duration gamma-ray bursts (LGRBs) and fast radio bursts (FRBs). The time delay (years to decades) between the SN and the QN, and the fragmented nature (i.e., millions of chunks) of the relativistic QN ejecta are key to yielding a robust LGRB engine. In our model, an LGRB light curve exhibits the interaction of the fragmented QN ejecta with turbulent (i.e., filamentary and magnetically saturated) SN ejecta which is shaped by its interaction with an underlying pulsar wind nebula (PWN). The afterglow is due to the interaction of the QN chunks, exiting the SN ejecta, with the surrounding medium. Our model can fit BAT/XRT prompt and afterglow light curves simultaneously with their spectra, thus yielding the observed properties of LGRBs (e.g., the Band function and the X-ray flares). We find that the peak luminositypeak photon energy relationship (i.e., the Yonetoku law), and the isotropic energy-peak photon energy relationship (i.e., the Amati law) are not fundamental but phenomenological. FRB-like emission in our model results from coherent synchrotron emission (CSE) when the QN chunks interact with non-turbulent weakly magnetized PWN-SN ejecta, where conditions are prone to the Weibel instability. Magnetic field amplification induced by the Weibel instability in the shocked chunk frame sets the bunching length for electrons and pairs to radiate coherently. The resulting emission frequency, luminosity and duration in our model are consistent with FRB data. We find a natural unification of high-energy burst phenomena from FRBs (i.e., those connected to CCSNe) to LGRBs including X-ray flashes (XRFs) and X-ray rich GRBs (XRR-GRBs) as well as superluminous SNe (SLSNe). We find a possible connection between ultra-high energy cosmic rays and FRBs and propose that a QN following a binary neutron star merger can yield a short duration GRB (SGRB) with fits to BAT/XRT light curves.
Quantifying the role of internal variability in the temperature we expect to observe in the coming decades
Authors: Maher Nicola , Lehner Flavio , Marotzke Jochem
Published: March 2020

On short (15-year) to mid-term (30-year) time-scales how the Earth’s surface temperature evolves can be dominated by internal variability as demonstrated by the global-warming pause or ‘hiatus’. In this study, we use six single model initial-condition large ensembles (SMILEs) and the Coupled Model Intercomparison Project 5 (CMIP5) to visualise the role of internal variability in controlling possible observable surface temperature trends in the short-term and mid-term projections from 2019 onwards. We confirm that in the short-term, surface temperature trend projections are dominated by internal variability, with little influence of structural model differences or warming pathway. Additionally we demonstrate that this result is independent of the model-dependent estimate of the magnitude of internal variability. Indeed, and perhaps counter intuitively, in all models a lack of warming, or even a cooling trend could be observed at all individual points on the globe, even under the largest greenhouse gas emissions. The near-equivalence of all six SMILEs and CMIP5 demonstrates the robustness of this result to the choice of models used. On the mid-term time-scale, we confirm that structural model differences and scenario uncertainties play a larger role in controlling surface temperature trend projections than they did on the shorter time-scale. In addition we show that whether internal variability still dominates, or whether model uncertainties and internal variability are a similar magnitude, depends on the estimate of internal variability, which differs between the SMILEs. Finally we show that even out to thirty years large parts of the globe (or most of the globe in MPI-GE and CMIP5) could still experience no-warming due to internal variability.
Escalating global exposure to compound heat-humidity extremes with warming
Authors: Li Dawei , Yuan Jiacan , Kopp Robert E
Published: March 2020

Heat stress harms human health, agriculture, the economy, and the environment more broadly. Exposure to heat stress is increasing with rising global temperatures. While most studies assessing future heat stress have focused on surface air temperature, compound extremes of heat and humidity are key drivers of heat stress. Here, we use atmospheric reanalysis data and a large initial-condition ensemble of global climate model simulations to evaluate future changes in daily compound heat-humidity extremes as a function of increasing global-mean surface air temperature (GSAT). The changing frequency of heat-humidity extremes, measured using wet bulb globe temperature (WBGT), is strongly related to GSAT and, conditional upon GSAT, nearly independent of forcing pathway. The historical ∼1°C of GSAT increase above preindustrial levels has already increased the population annually exposed to at least one day with WBGT exceeding 33°C (the reference safety value for humans at rest per the ISO-7243 standard) from 97 million to 275 million. Maintaining the current population distribution, this exposure is projected to increase to 508 million with 1.5°C of warming, 789 million with 2.0°C of warming, and 1.22 billion with 3.0°C of warming (similar to late-century warming projected based on current mitigation policies).
Extreme dry and wet spells face changes in their duration and timing
Authors: Breinl Korbinian , Di Baldassarre Giuliano , Mazzoleni Maurizio , Lun David , Vico Giulia
Published: March 2020

Dry spells are sequences of days without precipitation. They can have negative implications for societies, including water security and agriculture. For example, changes in their duration and within-year timing can pose a threat to food production and wildfire risk. Conversely, wet spells are sequences of days with precipitation above a certain threshold, and changes in their duration and within-year timing can impact agriculture, flooding or the prevalence of water-related vector-borne diseases. Here we assess changes in the duration and within-year timing of extreme dry and wet spells over 60 years (1958–2017) using a consistent global land surface precipitation dataset of 5093 rain gauge locations. The dataset allowed for detailed spatial analyses of the United States, Europe and Australia. While many locations exhibit statistically significant changes in the duration of extreme dry and wet spells, the changes in the within-year timing are less often significant. Our results show consistencies with observations and projections from state-of-the-art climate and water resources research. In addition, we provide new insights regarding trends in the timing of extreme dry and wet spells, an aspect being equally important for possible future implications of extremes in a changing climate, which has not yet received the same level of attention and is characterized by larger uncertainty.
Enlargement of oil droplets by using asymmetric structure of polyvinylidene fluoride membranes
Authors: Chiam C K , Azierah R , Rosalam S
Published: March 2020

This paper presents a study for enlarging the oil droplets by using the polyvinylidene fluoride (PVDF) membranes in a cross-flow membrane filtration system at the transmembrane pressures range between 0 and 4 bars. The PVDF membranes are fabricated by using phase inversion technique with different concentrations of coagulant ethanol (0 – 30 v/v%). Alkaline-surfactant-polymer (ASP) produced water is synthesised and tested as the feed solution with the oil droplets sized between 0.1 and 0.2 μm. Results show that the effect of the membrane formulations on the oil droplet coalescence is lesser as compared to the effect of the transmembrane pressures. More than 65% of the coalesced oil droplets in permeate having the diameters exceeding 1.0 μm although at least 50% of the membrane pores are larger than the oil droplets in the feed solutions. It is suggested that the tortuous structure of the membranes coalesced the oil droplets significantly.
PI/NCC- based carbon molecular sieve membranes for Hydrogen purification: Effect of aging times
Authors: Sazali N , Salleh W N W , Siregar J P , Othman M H D , Jaafar J , Gunawan T.
Published: March 2020

In this study, the effect of stabilization temperature on the performance of tubular carbon Upgrade the gas separation performance of the resultant carbon molecular sieve (CMS) membrane, a synthesized nanocrystalline cellulose (NCC) utilizing tissue paper as an added substance was included into the simpleton arrangement at pyrolysis temperatures of 800°C. This paper shows the inference of CMSs from BTDA-TDI/MDI polyimide (PI) arranged by means of a dip-coating strategy on an inorganic cylindrical help surface, trailed by a heat treatment (adjustment and carbonization) under Ar gas stream. Extraordinary consideration was given to the physicochemical attributes of the subsequent PI/NCC-based CMS and its comparing gas permeation properties. Pure gas permeation tests were performed utilizing H2, and N2 at room temperature. The gas permeation information showed that the CMS displayed an amazing performance contrasted with the polymeric membrane. Upgrade in the two gas permeance and selectivity were watched arranged with fresh CMS membrane, with H2N2 selectivity of 434.68±1.39, regarding the neat CMS. By controlling different aging times (fresh, 1 day, multi week, and 3 months), CMSs with various structures and properties were gotten.
CO2 utilization for combined gasification and sorption enhanced water-gas shift for syngas production of biochar
Authors: Chimpae Supanida , Wongsakulphasatch Suwimol , Vivanpatarakij Supawat , Glinrun Thongchai , Wiwatwongwana Fasai , Assabumrungrat Suttichai
Published: March 2020

Searching for alternative renewable energy to serve high demand of energy consumption has been of interest for decades. However, the production of energy comes with an emission of large amount of CO2, the main cause of global warming problem. As a consequence, improvement of energy production process in terms of increasing high efficiency and reducing CO2 emission are required [1]. This research verified the combined systems: biochar gasification and sorption-enhanced water gas shift reaction for the production of synthesis gas. The effect of calcium precursor on CaO-based sorbents, type of metal on multifunctional materials, and amount of co-feed CO2 as gasifying agent on process performances were focused on this work. Fixed-bed reactors were used for both gasification and sorption-enhanced water-gas shift experiments. Performances of the system were analyzed in terms of %biochar conversion, H2/CO ratio, and CO2 emission. The temperature used in the gasification process was fixed at 900°C and sorption-enhanced water-gas shift was 600°C at 1 atm. The results showed the sorbent CaO/Caj2Alj4O33 derived from calcium nitrate displayed the best performance for CO2 capture, whose CO2 capture capacity is 0.34 gCO2/g sorbent at 30%CO2v/v at 600°C. For the combined gasification and sorption-enhanced water-gas shift reaction, 98% biochar conversion can be obtained. Ni/CaO-Caj2Ali4O33 offered higher H2/CO ratio and CO2 emission when compared to Cu/CaO-Ca12Al14O33 at fixed feed molar ratio of H2O:CO2:O2:C = 0.5:0.5:0.125:1. The utilization of CO2 as gasifying agent at feed molar ratio of H2O:CO2:O2:C = 0.5:0.1:0.125:1 demonstrated the reduction of CO2 emission with the production of H2/CO ratio = 0.23.
PI/NCC Carbon Membrane: Effect of Heating Rates Towards Oxygen Separation Performance
Authors: Sazali N , Mamat R , Salleh W N W , Ismail A F , Aziz F , Mahyon N I
Published: March 2020

Separation of oxygen and nitrogen gas was considered by utilizing tubular carbon membrane (TCMs) arranged from polymeric precursors. A coating methodology called dip coating strategy was utilized to manufacture the TCMs utilizing P84 co-polyimide and Nanocrystalline cellulose (NCC) as the primary precursor and added additives individually. Past examination has demonstrated that properties of PI/NCC can be adjusted by changing the carbonization parameter i.e. time, temperature and condition. The statement of PI/NCC on the tubular supported help was utilized to deliver an assortment of TCMs for gas separation by basic carbonization process. In this examination, the heating rates was controlled to watch the impact of TCMs on gas permeation by setting the heat rates at 1, 3, 5, and 7 °C/min. It was demonstrating that the gas separation performance was profoundly influenced by the carbonization heating rates amid the manufacture of PI/NCC-based carbon membrane. Likewise, heat rates at (3 °C/min) demonstrates an enhancement in the membrane selectivity and separation performance.
Organic acid pretreatment of oil palm trunk biomass for fermentable xylose production
Authors: Bukhari N A , Jahim J M , Loh S K , Harun S , Nasrin A B
Published: March 2020

Green alternatives to chemical pretreatment in hydrolysing hemicellulose for efficient biorefineries are very much sought-after. In this study, we aimed to determine the effectiveness of several organic acids in hydrolysing hemicellulose of oil palm trunk biomass (OPTB) to form fermentable xylose. Various organic acids (citric acid, formic acid and oxalic acid) of different concentration (0.5-5.0%) were assessed to find a suitable catalyst in hydrolysing OPTB for reaction time (15-120 min) at a fixed temperature (120°C), aiming for high xylose selectivity. Of these, oxalic acid was shown the most effective in solubilizing hemicellulose from OPTB, producing a maximum xylose yield of ∼70% at the optimum catalyst concentration of 5.0% (w/v) for 120 min. The main components in the hemicellulosic hydrolysate were xylose, 16.26±0.30 g/L; glucose, 2.11±0.04 g/L; arabinose, 0.19±0.05 g/L; acetic acid, 5.59±0.07 g/L and trace amount of furfural and hydroxylmethylfurfural (HMF). The resulting xylose recovery was comparable to the conventional pretreatment using dilute sulphuric acid, thus provides an alternative approach of biomass pretreatment for process improvement. The fermentability of xylose from the hemicellulosic hydrolysate was further evaluated for succinic acid production.
Characterization of semi-refined carrageenan film plasticized with glycerol incorporated with Persicaria minor extract as antioxidant additives
Authors: Yahaya W A W , Husaini N H , Zaharudin F N H , Azman N A M
Published: March 2020

Semi refined carrageenan (2%w/w) plasticized with 0.9% (w/w) glycerol (G) added withPersicaria minor(PM) extract and 0.4% (w/w) BHA as antioxidant additives for the development of active packaging films. The extraction of PM using 75% (v/v) ethanol: water ratio showed the highest polyphenol content with 176.80±4.37 Gallic Acid Equivalent (GAE)/L sample and 94.65±0.17% inhibition analyzed using DPPH antioxidant activity (p<0.05). The characterization of SRC-G based film containing 0.4, 1.0, 1.5 and 2.0% (w/w) PM and BHA were observed using FTIR, mechanical and physical properties of the treated films. FTIR spectrum band showed insight analysis of PM extract and BHA with carrageenan. SRC film plasticized with glycerol improved overall physical properties including thickness, barrier and flexibility and increased tensile strength and elongation at break compared to the SRC film only (p<0.05). The active films with PM extracts (2.0% w/w) exhibited good mechanical properties with tensile strength and elongation at break with 28.01±0.17 and 37.37±0.29 respectively (p<0.05). The addition of PM extract in SRC films increased the moisture content and opacity as proportionally to the concentration of PM extracts. Film treated with 2.0% PM showed lowest value of films solubility compare to all sample (p<0.05). Hence, the characterization measurement of SRC based films demonstrated great potential with natural extract formulation for the development of active film packaging for food products.
Effect of water alternating gas (WAG-N2) after water or gas flooding on crude oil recovery in sandstone reservoirs
Authors: Alagorni A. H , Yaacob Z. B , Nour A. H , Junin R. B
Published: March 2020

Previous studies showed that nitrogen injection could recover oil up to 45-90 % of the Original Oil in Place (OOIP) of the reservoir. Additionally, when applying Water Alternating Gas (WAG-N2), recovery can be improved by combining gas and water and having better gas mobility control by reducing viscous fingering and density tonging, as well as contacting the un-swept zones, leading to an improved microscopic displacement. The objective of this study is to determine the total Oil Recovery Factor (ORF) of WAG-N2 process either after Water Flooding (WF) or after Gas Flooding (GF) in sandstone reservoirs. The results showed that with the following conditions: 38.8° API gravity oil, injection rate of 0.6cm3/m, injection pressure of 2000 psi (1378.59 kpa), WAG rate of 1:1, and Sand pack temperature of 70°C, the maximum ultimate ORF was 71.2 % in WAG after WF and 52.42 % of WAG after GF. On the other hand, WF provided ORF of 65.6 % when compared with GF recovery (29.03 %).
PHYTOREMEDIATION: TREATING EUTHROPHIC LAKE AT KotaSAS LAKESIDE, KUANTAN BY AQUATIC MACROPHYTES
Authors: Muhammad Haziq J , Farah Amalina I , Abdul Syukor AR , Sulaiman S , Nurul Islam Siddique Md , Woon SXR
Published: March 2020

This investigation was embraced ex-situ to investigate the capability of the submerged plants’ water hyacinth (Eichornia crassipes) and water lettuce (Pistia stratiotes L.) as phytoremediation aquatic macrophytes for nutrients removal from a eutrophic lake situated at KotaSAS Lakeside surrounded by residential area as the risk of algae bloom can be avoided. The present of mankind activities such as sewage runoff and agricultural towards water bodies, the eutrophication process being speed up. The capability of these plants to evacuate certain parameters not just supplements while additionally including BOD5, COD, TSS, Turbidity, and heavy metals. The technique for investigation of lake water was alluded by Standard Method for Examination of Water and Wastewater. Water lettuce displayed extraordinary nitrate removal effectiveness up to 94% however this plant species shrivelled from week 2 of the examination because of an absence of nitrate supply and caused an expansion in phosphorus concentration. Then, water hyacinth indicates relentless evacuation productivity with a normal of 82% for nitrate and phosphorus. Other than that, water hyacinth indicates 88% and 72% of TSS and turbidity expulsion effectiveness which can improve the clarity of lake water. With this accomplishment gained in phytoremediation innovation utilizing water hyacinth, it is of most significance for this innovation to be executed in bigger scales in the future.
Cultivation of microalgae in fluidized bed bioreactor: impacts of light intensity and CO2 concentration
Authors: Rosli S S , Lim J W , Lam M K , Ho Y C , Yeong Y F , Mohd Zaid H F , Chew T L , Aljunid Merican Z M , Mohamad M
Published: March 2020

Harvesting of suspended microalgae biomass will generally incur excessive time and intensive energy due to low biomass density. Microalgae cultivation via fluidized bed bioreactor was introduced to tackle the harvesting process in which the support material was fluidizing within the culture medium, allowing the microalgae to settle onto the surface of fluidized material and grow thereafter. The Central Composite Design (CCD) was adopted to design the experiments for optimization of attached microalgae growth onto the fluidized bioreactor. The optimization condition occurred at 216 μmol/m2 s light intensity and 9% CO2 concentration with maximum biomass concentration (Xmax) and maximum specific growth rate μmax) of attached microalgae obtained at 0.692 g/L and 0.028 1/h, respectively. The Verhulst logistic kinetic model illustrated the attached microalgae growth from lag to stationary phase, supporting the use of this model to represent the kinetic of attached microalgae growth onto the fluidized bed bioreactor under various condition.
Synthesis of Ionic Salt for Calcite and Barite Solid Scale Dissolution
Authors: Sulaiman M H , Adam F , Yaacob Z , Mohd Noor Z
Published: March 2020

The most common well intervention work to solve solid scale problem in oil production is a treatment to remove or inhibit the solid scale. Calcite (CaCO3) and barite (BaSO4) are two of the most common solid scale found in the oil well tubular and piping. Often, acid treatment such as hydrochloric acid is used to dissolve the solid scale. However, acid is highly corrosive and harmful to handle in the challenging environment of oilfield operation. A new generation of less corrosive solid scale dissolver includes functional group such as a carboxylic group due to its ability to chelate metals ions. This study utilised economical and non-toxic materials, monosodium glutamate (MSG), as the starting materials to synthesis solid scale dissolver with the carboxylic group as the main functional group presence. The double step acidification of MSG produces glutamic acid hydrochloride (GluCl). It is solid at room temperature and soluble in water makes it safer to transport and handle in the challenging environment of oilfield operation. Dissolution test shows that GluCl can dissolve more than 3000 ppm of calcium at a concentration of just 20g/L.
Evaluation on the factors influencing the deposition of wax using full factorial design
Authors: Ridzuan N , Azhar A A , Subramanie P
Published: March 2020

The purpose of this study is to determine the rate of wax deposition of Malaysian crude oil by evaluating the operational factors using full factorial design (FFD) approach (Design Expert version 7.1.6). Four factors were studied, which are rotation speed (A), cold finger temperature (B), experimental duration (C) and type of wax inhibitor (D), Poly(ethylene-co-vinyl acetate) (EVA) and xylene were used as a wax inhibitor. The individual effects of each factor and its interaction effects towards the response variable were studied. The result demonstrated that fewer wax deposit was obtained (0.0055 g) when optimal conditions of 2 h duration with 600 rpm rotation speed at 15°C cold finger temperature and EVA as an inhibitor were used. From the analysis of variance (ANOVA), factor B was found to be the main factor in affecting the wax deposit formation. However, the interaction between factors A and D shows the highest influence to reduce wax deposition. Furthermore, the model is designated with high determination coefficient (R2= 0.8221), which explains 82.21% of the variability in the response. Hence, it can be concluded that factor B, and interaction between factors A and D need to be focused in controlling the parameters to minimize wax deposition.
Flow Behaviour in the calciner of cement production
Authors: Sooklon P , Jiamrittiwong P , Pana-Suppamassadu K , Swadchaipong N , Srisurat T
Published: March 2020

Calciner was one of the cement production unit that used momentum, heat, mass distribution and chemical reaction to change calcium carbonate into calcium oxide. One of the important processes was fluid flow. Thus, the computational fluid dynamic was used to predict the flow behavior in the calciner. Regarding gas hydrodynamics, the Navier-Stokes equations were applied along with all practical operating conditions. The simulation results showed that both sides of calciner had the same velocity. High velocity was originated from decreasing of flow area. The velocity in the conjunction zone between TAD and Kiln had high unsteady velocity distribution but, in the higher level, the velocity approached a steady state. This simulation model could be used as a preliminary data in order to predict the temperature distribution.