bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Si doping on the ferromagnetic properties of delta doped GaMnN nanorods
Authors: Wadekar P. V. , Xu C. L. , Chang C. W. , Lin C. H. , Yen J. H. , Chen Q. Y. , Tu L. W.
Published: December 2020

Delta doping (δ-doping) of group-III nitride-based nanostructures such as nanorods (NRs) with transition metals such as manganese (Mn) can lead to one-dimensional (1D) diluted magnetic semiconductors (DMSs). In order to investigate the effects of free carrier doping on the structural, electrical, and magnetic properties of such delta-doped 1D structures, we have used nanosphere lithography to grow uniform arrays of vertically aligned NRs with fixed aspect ratios on single crystal Al2O3 substrates using plasma-assisted molecular beam epitaxy (PAMBE). The precise control of the elemental flux intensity and duration, facilitated by PAMBE, enables the growth of phase-pure nanostructures, resulting in spatial separation on the order of few nanometers, between the δ-Mn layer and the free carriers in the Si:GaN layer. Chemical quantification verifies the presence of Mn and Si, while Raman spectroscopy shows that Si doping enhances the local vibration mode associated with Mn bonded to N as well as the disorder-activated mode. The free carriers do not diminish the inherent magnetic ordering in these 1D structures, while magnetic measurements show a stability in the signal.
Carrier capture kinetics, deep levels, and isolation properties of
β
-Ga2O3 Schottky-barrier diodes damaged by nitrogen implantation
Authors: De Santi C. , Fregolent M. , Buffolo M. , Wong M. H. , Higashiwaki M. , Meneghesso G. , Zanoni E. , Meneghini M.
Published: December 2020

In this paper, we analyze the stability of the performance of β-Ga2O3 Schottky barrier diodes (SBDs) damaged by nitrogen implantation, based on electrical characterization and deep-level spectroscopy. We demonstrate that N-implanted SBDs show a high level of isolation, which can be further improved by electron trapping promoted by current flow and temperature. Charge trapping leads to a shift in the current–voltage curve to more positive bias, a positive effect lasting for hundreds of seconds at room temperature and fully recovered only after 200 s even at 350 K. This charge trapping process takes place in the depletion region of the Schottky diode, in a defect located 0.72 eV below the conduction band, possibly related to gallium vacancies. A model for explaining the trapping kinetics and processes is proposed, based on differential rate equations, highlighting two capture processes: charge injection from the n-type Ga2O3 into the space charge region and thermionic emission from the anode metal to the deep level.
Skewed thermodynamic geometry and optimal free energy estimation
Authors: Blaber Steven , Sivak David A.
Published: December 2020

Free energy differences are a central quantity of interest in physics, chemistry, and biology. We develop design principles that improve the precision and accuracy of free energy estimators, which have potential applications to screening for targeted drug discovery. Specifically, by exploiting the connection between the work statistics of time-reversed protocol pairs, we develop near-equilibrium approximations for moments of the excess work and analyze the dominant contributions to the precision and accuracy of standard nonequilibrium free-energy estimators. Within linear response, minimum-dissipation protocols follow the geodesics of the Riemannian metric induced by the Stokes friction tensor. We find that the next-order contribution arises from the rank-3 supra-Stokes tensor that skews the geometric structure such that minimum-dissipation protocols follow the geodesics of a generalized cubic Finsler metric. Thus, near equilibrium, the supra-Stokes tensor determines the leading-order contribution to the bias of bidirectional free-energy estimators.
Thickness dependence of elliptical planar Hall effect magnetometers
Authors: Nhalil Hariharan , Das Proloy T. , Schultz Moty , Amrusi Shai , Grosz Asaf , Klein Lior
Published: December 2020

We fabricate elliptical planar Hall effect magnetometers with Permalloy thickness ranging between 25 and 200 nm. We study the thickness dependence of their equivalent magnetic noise by examining the effect of the layer thickness on the signal and noise including Joule heating contributions. Sensors with a thickness of 50 nm achieve equivalent magnetic noise as low as ∼24 pT/√ Hz at 50 Hz and ∼36 pT/√ Hz at 10 Hz, which are the best reported values for any type of magnetic sensor of similar or smaller size. These results are achieved without the use of magnetic flux concentrators, which helps to reduce the sensor volume while improving its spatial resolution and reducing the complexity and time of its production and, hence, its potential cost. We discuss different routes for further resolution improvements.
Importance learning estimator for the site-averaged turnover frequency of a disordered solid catalyst
Authors: Vandervelden Craig A. , Khan Salman A. , Peters Baron
Published: December 2020

For disordered catalysts such as atomically dispersed “single-atom” metals on amorphous silica, the active sites inherit different properties from their quenched-disordered local environments. The observed kinetics are site-averages, typically dominated by a small fraction of highly active sites. Standard sampling methods require expensive ab initio calculations at an intractable number of sites to converge on the site-averaged kinetics. We present a new method that efficiently estimates the site-averaged turnover frequency (TOF). The new estimator uses the same importance learning algorithm [Vandervelden et al., React. Chem. Eng. 5, 77 (2020)] that we previously used to compute the site-averaged activation energy. We demonstrate the method by computing the site-averaged TOF for a simple disordered lattice model of an amorphous catalyst. The results show that with the importance learning algorithm, the site-averaged TOF and activation energy can now be obtained concurrently with orders of magnitude reduction in required ab initio calculations.
Efficiency improvement analysis of nano-patterned sapphire substrates and semi-transparent superlattice contact layer in UVC light-emitting diodes
Authors: Huang Chia-Yen , Tsai Chia-Lung , Huang Cheng-Yao , Yang Rong-Yu , Wu YewChung Sermon , Yen Hung-Wei , Fu Yi-Keng
Published: December 2020

UVC light-emitting diodes (LEDs, λ = 275 nm) with different types of contact layers and sapphire substrates were demonstrated on high-quality AlN templates. For LEDs on flat sapphire substrates (FSSs), replacing the absorbing p-GaN contact with p-AlGaN short-period superlattices (p-SPSLs) strongly enhanced the emission along the substrate normal. The integrated external quantum efficiency (EQE) increased from 2.4% to 3.9% under I = 350 mA. For LEDs with a p-SPSL contact, replacing the FSS with nano-patterned sapphire substrates slightly deteriorated the quality of epitaxy, but the overall EQE is still enhanced to 4.4% under I > 350 mA without lens encapsulation. According to the far-field intensity measurement, the light extraction is better improved along the high emission angle to the substrate normal. The interplay among substrates, dipole polarization, and EQE enhancement factors was further analyzed and discussed in the context.
Do reservoir computers work best at the edge of chaos?
Authors: Carroll T. L.
Published: December 2020

It has been demonstrated that cellular automata had the highest computational capacity at the edge of chaos [N. H. Packard, in Dynamic Patterns in Complex Systems, edited by J. A. S. Kelso, A. J. Mandell, and M. F. Shlesinger (World Scientific, Singapore, 1988), pp. 293–301; C. G. Langton, Physica D 42(1), 12–37 (1990); J. P. Crutchfield and K. Young, in Complexity, Entropy, and the Physics of Information, edited by W. H. Zurek (Addison-Wesley, Redwood City, CA, 1990), pp. 223–269], the parameter at which their behavior transitioned from ordered to chaotic. This same concept has been applied to reservoir computers; a number of researchers have stated that the highest computational capacity for a reservoir computer is at the edge of chaos, although others have suggested that this rule is not universally true. Because many reservoir computers do not show chaotic behavior but merely become unstable, it is felt that a more accurate term for this instability transition is the “edge of stability.” Here, I find two examples where the computational capacity of a reservoir computer decreases as the edge of stability is approached: in one case because generalized synchronization breaks down and in the other case because the reservoir computer is a poor match to the problem being solved. The edge of stability as an optimal operating point for a reservoir computer is not in general true, although it may be true in some cases.
Calcineurin controls proximodistal blastema polarity in zebrafish fin regeneration
Authors: Cao Zigang , Meng Yunlong , Gong Fanghua , Xu Zhaopeng , Liu Fasheng , Fang Mengjie , Zou Lufang , Liao Xinjun , Wang Xinjuan , Luo Lingfei , Li Xiaokun , Lu Huiqiang
Published: December 2020

Significance

Why some animals, but not others, respond to injury with extensive regeneration is an outstanding question and attracts considerable research interest. Planarian flatworms possess a polarity system throughout their anteroposterior axis that specifies the identity of missing tissues at wound sites. The regeneration of vertebrate appendages involves distal growth. However, whether vertebrate appendages can undergo bidirectional regeneration along the proximodistal axis remains unclear. Our study demonstrates that unidirectional blastema regeneration polarity occurs in zebrafish fins along the proximodistal axis. We identified calcineurin as a molecular switch that specifies the blastema of the PCE and controls regeneration polarity in zebrafish fins. Our results are of great importance for future regeneration polarity studies on vertebrates.
Tyrosine phosphorylation-dependent localization of TmaR that controls activity of a major bacterial sugar regulator by polar sequestration
Authors: Szoke Tamar , Albocher Nitsan , Govindarajan Sutharsan , Nussbaum-Shochat Anat , Amster-Choder Orna
Published: December 2020

Significance

In recent years, we have learned that bacterial cells have intricate spatial organization despite the lack of membrane-bounded organelles. The endcaps of rod-shaped bacteria, termed poles, are emerging as hubs for sensing and responding, but the processes involved in positioning macromolecules there are largely unknown. We discovered a protein, TmaR, whose polar localization depends on a phospho-tyrosine modification. We show that TmaR controls the activity of EI, the major regulator of sugar metabolism in most bacteria, by polar sequestration and release. Notably, TmaR is essential for survival in conditions that
Escherichia coli
often encounters in nature. Hence, TmaR is a key regulator that connects tyrosine phosphorylation, spatial regulation, sugar metabolism, and survival in bacteria.
The retromer is co-opted to deliver lipid enzymes for the biogenesis of lipid-enriched tombusviral replication organelles
Authors: Feng Zhike , Inaba Jun-ichi , Nagy Peter D.
Published: December 2020

Significance

Replication of RNA viruses depends on the biogenesis of viral replication organelles (VROs). However, formation of VROs is not well understood. Using tombusviruses and the model host yeast, we discovered that the highly conserved host retromer complex is critical for the formation of VROs. Tombusvirus replication protein interacts with the retromer complex, leading to the recruitment of the retromer and its cargoes into VROs. The co-opted retromer tubular transport carriers deliver important enzymes required for lipid biosynthesis and lipid modifications that are needed for membrane biogenesis for efficient VRO assembly. Compartmentalization of these co-opted lipid enzymes within VROs gives a key advantage for tombusviruses to replicate in an optimized microenvironment and delay the antiviral responses of the hosts.
Pixel-based open-space microfluidics for versatile surface processing
Authors: Goyette Pierre-Alexandre , Boulais Étienne , Tremblay Maude , Gervais Thomas
Published: December 2020

Significance

Automated liquid handling is of utmost importance for life sciences, pharmaceutical research, and surface engineering. Despite its ubiquitous presence, the last decades’ advances in this domain have mainly consisted of the robotization of the human pipetting movement, with its intrinsic limitations. In this article, we lay the foundation for the pixelated chemical display (PCD), a liquid-handling system based on open-space microfluidics. This device uses the streaming of fluids through independent flow subunits to tessellate a surface with hundreds of reagents simultaneously. PCDs distinguish themselves from previous technology by offering a fast dilution-free reagent switching and a precise yet multiplexable spatiotemporal control of fluids on surfaces. PCDs will be of use in life sciences and for maskless surface processing.
Cooperative formation of porous silica and peptides on the prebiotic Earth
Authors: Navrotsky Alexandra , Hervig Richard , Lyons James , Seo Dong-Kyun , Shock Everett , Voskanyan Albert
Published: December 2020

Significance

Although catalysis by mineral surfaces has been considered to be important in prebiotic chemistry, the role of porous silica phases, with reactions taking place within specific confined environments, has not been explored. This paper proposes that structure direction through interaction of dissolved silica with organic species in aqueous solution produces porous silica catalysts for prebiotic organic reactions to form larger polymerized molecules, with possible control of chirality. This process may involve feedback and amplification if the organics produced by catalysis can also act as structure-directing agents for enhanced synthesis of the catalytic silica structures. To our knowledge, such structure direction and catalysis, though well known in materials science, have not been considered previously in the context of prebiotic chemistry.
Modeling gradient processes in Polabian vowel chain shifting and blocking
Authors: Burns Roslyn
Published: December 2020

This paper presents an analysis of two interacting sound changes in the extinct West Slavic language Polabian. Polabian is
known to have two types of vowel innovations: (i) the incorporation of acoustic properties from consonant secondary co-articulations (either
palatalization or velarization) and (ii) a systematic rotation of vowels (Timberlake 1995). This
paper argues that the innovation in (ii) is a vowel chain shift similar to those analyzed in Labov
(1994). Unlike the other languages surveyed in Labov (1994), Polabian has phonologically
predictable exceptions to the general direction of vowel movement through the acoustic space. Unlike previous work on Polabian, this paper
proposes that the vowel chain shift operated simultaneously with the innovation in (i) resulting in phonologically predictable exceptions.
This paper tests Timberlake’s (1995) proposal and the current proposal in a Harmonic Grammar
(Flemming 2001) which uses Purcell’s (1979) acoustic
data from Russian as a proxy. The model only captures the correct distribution of vowel reflexes under the assumption that co-articulatory
based innovations and vowel chain shifting were active at the same time.
Understanding the role of energetic particles during the growth of TiO2 thin films by reactive magnetron sputtering through multi-scale Monte Carlo simulations and experimental deposition
Authors: Tonneau R , Moskovkin P , Muller J , Melzig T , Haye E , Konstantinidis S , Pflug A , Lucas S
Published: December 2020

In this paper, a previously established 3D multi-scale simulation chain of plasma deposition process, based on a combination of a direct simulation Monte Carlo (gas phase) algorithm and a kinetic Monte Carlo (kMC) (film growth) code, is improved by the addition of a particle-in-cell Monte Carlo collision algorithm in order to take into account and clarify the role of charged particles. The kinetic Monte Carlo code is also extended with a binary collision approximation algorithm to handle charged particles. This modelling strategy is successfully applied to the growth of TiO2 thin films by means of reactive magnetron sputtering. In order to highlight the effects of negative oxygen ions, two substrate locations are selected: one in the median plane of the targets and another one off the median plane. The model efficiently predicts the densities and fluxes of both charged and neutral particles towards the substrate. Typical results such as particle densities, the discharge current density and ion flux onto the target, and the various substrate locations are calculated. The angular distribution and energy distribution of all involved particles are sampled at these very same substrate locations and the nanoscale modelling (NASCAM) code, implementing the kMC approach, uses these results to explain the morphology of the experimentally deposited coatings. The changes throughout the transition from metallic deposition to stoichiometric TiO2 of the columnar structure of the deposited films is explained by the suppression of the atom diffusion on the growing film due to Ti oxidation. Moreover, the high-energy negative atomic oxygen ions originating from the targets are identified as the origin of the abnormally low inclination of the columnar structure experimentally observed for the oxide mode coatings. Measurements of the normalized energy flux (energy per deposited atom) are experimentally investigated to support and highlight the important role of energetic particles during film growth.
Programmable terahertz vortex beam reflectarray antenna based on a graphene phoenix unit cell
Authors: Soleimani Hadi , Oraizi Homayoon
Published: December 2020

In this paper, for the first time, the concept, analysis and equivalent circuit of a phoenix graphene patch (PGP) unit cell is presented. It is shown that a full 360° phase range can be realized by this unit cell, unlike common graphene patch unit cells, by only separately changing the physical or electrical parameters. Then, a reflectarray antenna based on the PGP cell is designed. The required phases are easily realized by only changing the element dimensions in the cell. The gain and radiation efficiency of the designed antenna are 26 dBi and 75%, respectively. Finally, a programmable vortex beam reflectarray is proposed, whereby the required phases are realized only by the chemical potential of the graphene sheet. The structure is discretized to five sections in the radial direction and eight sections in the azimuth direction. In comparison to other structures, the proposed design can easily generate different vortex beams in real-time by changing the biasing voltages of these sections.
ML-based Telegram bot for real estate price prediction
Authors: Salem Hamza , Mazzara Manuel
Published: December 2020

Telegram chatbots are one of the main sections in Telegram applications that get more attention and provide huge business opportunities for companies nowadays. Also, Machine learning algorithms have been used in numerous fields and industries and one of the main growing markets is real estate. It is already helping real estate agents to respond more quickly to clients’ questions and develop landing pages that fit customers’ needs. However, one of the main time-consuming stages for a real estate agent is the process of answering questions about price per location and knowing which locations clients are interested in. In order to solve these problems, we have built a telegram chatbot to answer customers of any real estate agent with the price of a real estate property based on their current Geolocation. This bot can predict the price of a real estate property using room numbers, Geolocation, and surface area in square meters. These are the inputs for machine learning algorithms to give an approximate price. The bot can predict based on the source of the data-set, for example, we have collected our data from classified ads website for real estate in Amman, Jordan. We have used python and web scraping library for data extraction, cleaning, and transformation. As a result, by using Geolocation we have increased the model accuracy to 1.3X and our bot can be replicated in any markets based on the dataset. We believe our work can be taken to different markets and make real estate agent’s job easy and more profitable by changing leads to potential customers thought answering their questions.
A new method for creating nanoprofiled epitaxial silicon carbide surfaces on silicon
Authors: Grashchenko A. S. , Kukushkin S. A. , Osipov A. V.
Published: December 2020

In the presented work, the method of substitution of atoms was used to form an epitaxial nanostructured profiled SiC layer with a given geometry on a Si crystal. The found conditions for the synthesis of the SiC layer with the initial geometry and morphology of the Si surface preserve the initial state, covering layered SiC, completely repeating the profile of the initial Si surface.
Synthesis of mixed germanium tin nanoparticles by spark-discharge
Authors: Lizunova A A , Borisov V I , Masnaviev B I , Solovey V R , Ivanov V V
Published: December 2020

The paper represents the investigations of dimensional and structural properties of nanoparticles produced by pulsed-periodic spark discharge by simultaneous electrical erosion of germanium and tin electrodes in inert atmosphere. Two alloys of GeSn nanoparticles with different mass fractions of tin were obtained by altering the polarity of the electrodes. The nanoparticles’ sizes from 4 to 45 nm were observed. It was shown that the samples consist of core-shell nanoparticles agglomerates, where both β-tin crystals and cubic germanium ones presence as a core; the shell is a mixed germanium tin oxide. Furthermore, a shift of a maximum of Raman peak by 3.5 cm−1 to lower wave numbers with an increase in relative fraction of tin was detected.
Study of droplet formation regimes in a pressure control mode in microfluidic chip for screening cell libraries
Authors: Filatov N A , Bukatin A S
Published: December 2020

To create a high throughput system for screening single cells in “water-in-oil” droplets, a key role is played by the method of controlling fluid flows in a microfluidic droplet generator. This is due to the fact that it is required to obtain monodisperse drops-microcapsules, place cells in them and be able to manipulate them. For these purposes, not only systems based on syringe pumps are suitable, but also pressure control units may be used. Unfortunately, pressure control instruments on the market for researchers are represented by only a few companies and are quite expensive. In this work, we develop a homemade microfluidic pressure controller based on SMC ITV 0010 pneumatic regulators and show its operability. Also, we investigated the conditions for reproducible generation of water-in-oil emulsions in a microfluidic flow focusing droplet generator by pressure driven fluid flows.
The influence of quantum well geometry on wavelength of AlInGaAs/InP laser diodes
Authors: Chelny A , Akhmerov Yu , Savchuk A , Zharkova A , Rabinovich O , Mezhenny M , Aluyev A , Zakusov M , Orlova M , Murashev V , Didenko S
Published: December 2020

The AlGaInAs structure was successfully grown on the InP substrate by MOCVD method. The active region was studied by Auger spectroscopy. The thicknesses and compositions of the quantum wells did not coincide with the theoretical ones. The mathematical model which correlate with investigation results is proposed.
Long–range night vision camera based on SWIR photocathode
Authors: Smirnov K J , Davydov V V , Glinushkin A P
Published: December 2020

Technological aspects of manufacturing SWIR sensitive detector on the basis of InP/InGaAs/InP photocathode and electron-bombarded CCD are given. Scheme of the digital camera for long distance detection is represented. SWIR camera operating mode and properties in case of implementation of impulse laser source are discussed.
Formation and SERS efficiency of periodic metal-dielectric nanostructures
Authors: Gangrskaia E , Babich E , Scherbak S , Reduto I , Redkov A , Lipovskii A
Published: December 2020

We studied silver nanoparticles combined with periodic gratings on a glass surface. The gratings were fabricated by selective etching of the glass slide patterned by thermal poling. The nanoparticles were grown on the bottom of the gratings’ grooves by out-diffusion technique. Obtained nanostructures supported both plasmonic and grating optical resonances and demonstrated SERS enhancement two times higher than one of the pure plasmonic structure.
Possibilities of using spectral analysis in method of nuclear magnetic spectroscopy for condensed media investigation
Authors: Makeev S S , Davydov V V , Grevtzeva A S , Glinushkin A P , Matorin D N
Published: December 2020

The necessity of developing a mathematical model for converting the recorded NMR signal using a modulation technique into the spectrum for conducting the composition of the medium under study is substantiated. A mathematical model has been developed to represent the NMR signal in the form of a spectrum, taking into account the features of its registration from condensed matter. Spectra of calculated and experimental NMR signals are presented. Them comparison are completed.
Modeling of current generation process in an aligned carbon nanotube under the action of strain gradient
Authors: Il’ina M V , Guryanov A V , Osotova O I , Blinov Yu F , Il’in O I
Published: December 2020

The results of theoretical and experimental studies of the current generation process in an aligned carbon nanotube (CNT) during its deformation are presented. It is theoretically established that there is a strain gradient equal to 8 in the aligned nanotube under the influence of the external field strength of 1010 V/m. The piezoelectric coefficient of the CNT at a diameter of 92 nm and a length of 2.2 µm is empirically determined and amounted to 0.107 C/m2. It is theoretically established that a CNT strain gradient of 8 leads to a current generation of up to 12 nA. It is shown that the modeling results correlate with experimental data. The obtained results can be used to develop the nanopiezotronics devices based on aligned carbon nanotubes.
Numerical study of Schottky diode based on single GaN NW on Si
Authors: Shugurov K Yu , Mozharov A M , Mukhin I S
Published: December 2020

Numerical modelling of Schottky diode formed by single GaN nanowire on Si substrate was performed. Two metals, namely, gold and platinum forming the Schottky barrier were considered. The potential barrier height was calculated taking into account occurrence of image force as well as Fermi level pinning at metal/semiconductor interface. Volt-ampere characteristics were obtained for different NW doping levels considering Wentzel–Kramers–Brillouin tunneling model. Cutoff frequencies are evaluated from current-time relaxation curves for different NW lengths and doping levels. It is shown that such diode structure demonstrates high-speed performance with cutoff frequency in the range from 0.1 to 0.9 THz for both studied metals.
Development and research of a technology for producing a low-dimensional porous platinum-based catalyst by thermal evaporation in vacuum on an ion-exchange polymer membrane of a hydrogen generator electrolytic cell
Authors: Nesterov S A , Gurin S A , Pecherskaya E A , Shelakhaev D A , Fimin A V
Published: December 2020

The use of hydrogen structures as a universal energy carrier led to its application in various fields of industry. Currently used production methodologies make it possible to produce systems with high reliability and a long service life. However, at the moment, the creation of such structures is limited by the lack of natural origin materials necessary for the production of such structures, which leads to the search for alternative and most universal manufacturing methods against the background of increasing needs.
Fabrication of NbN/SiNx:H/SiO2 membrane structures for study of heat conduction at low temperatures
Authors: Titova N A , Baeva E M , Kardakova A I , Goltsman G N
Published: December 2020

Here we report on the development of NbN/SiNx:H/SiO2-membrane structures for investigation of the thermal transport at low temperatures. Thin NbN films are known to be in the regime of a strong electron-phonon coupling, and one can assume that the phononic and electronic baths in the NbN are in local equilibrium. In such case, the cooling of the NbN-based devices strongly depends on acoustic matching to the substrate and substrate thermal characteristics. For the insulating membrane much thicker than the NbN film, our preliminary results demonstrate that the membrane serves as an additional channel for the thermal relaxation of the NbN sample. That implies a negligible role of thermal boundary resistance of the NbN-SiNx:H interface in comparison with the internal thermal resistance of the insulating membrane.
Formation of luminescent nanoclusters by etching silver nanoparticles with biomolecules
Authors: Chuiko Ya V , Kubenko V G , Reveguk Z V , Kapitionova M A , Kononov A I
Published: December 2020

Metal nanoparticles and nanoclusters are progressively studied for use in various biomedical applications such as imaging, drug delivery, and therapies. Therefore, considering the interaction of biopolymers with metal nanostructures becomes vital for their efficient application. Luminescent metal nanoclusters are now widely considered as potential sensor applications. In this work we considered the interaction of silver nanoparticles with some proteins and oligonucleotides. We observed that biomolecules in some cases can effectively dissolve nanoparticles and lead to the formation of silver nanoclusters.
Diffusive dynamics and jamming in ensembles of robots with variable friction
Authors: Rozenblit A D , Porvatov V A , Petrova D A , Khakhalin I S , Kotlyar K P , Gritsenko G Yu , Evreiskaya A A , Lebedeva M F , Kretov E I , Filonov D S , Souslov A , Olekhno N A
Published: December 2020

In the present paper, we experimentally study the diffusive dynamics in ensembles of self-propelled and self-rotating bristle-bots. Considering the dependence of the system dynamics on the packing density of robots as well as on the friction between individual robots, we show that the friction slightly affects the diffusive dynamics but leads to a significant change in the jamming transition corresponding to the formation of rigid clusters of robots.
Comment on ‘fluctuation-dominated phase ordering at a mixed order transition’
Authors: Godrèche Claude
Published: December 2020

Renewal processes generated by a power-law distribution of intervals with tail index less than unity are genuinely non-stationary. This issue is illustrated by a critical review of the recent paper by Barma, Majumdar and Mukamel (2019 J. Phys. A
52 254001), devoted to the investigation of the properties of a specific one-dimensional equilibrium spin system with long-range interactions. We explain why discarding the non-stationarity of the process underlying the model leads to an incorrect expression of the critical spin–spin correlation function, even when the system, subjected to periodic boundary conditions, is translation invariant.
Dielectric Breakdown Strength and Energy Storage Density of CCTO-ZBS Electroceramic
Authors: Saari Muhammad Qusyairie , Mohamed Julie Juliewatty , Sulaiman Muhammad Azwadi , Rahman Mohd Fariz Abd , Ahmad Zainal Arifin , Jamil Mohamad Kamarol Mohd , Rashid Mohd Warikh Abd , Yuwono Akhmad Herman
Published: December 2020

The effect of ZnO-B2O3-SiO2 (ZBS) glass additives to the microstructure and electrical properties of CaCu3Ti4Oi2 (CCTO) electroceramic has been successfully investigated in this research. CCTO and ZBS glass additives were prepared via solid state reaction and melt quench techniques, respectively. Raw materials of both CCTO and ZBS were wet mixed separately for 24 hours, dried overnight and the CCTO powder was calcined at 900 °C for 12 hours using an electrical carbolite furnace. After that, the ZBS powder was melted at 1400 °C for 2 hours using an elevator hearth furnace. The ZBS glass was grinded to form fine powder. Different weight percentages (0, 1, 3, 5, 7 and 10 wt%) of ZBS glass powder were added into CCTO (CCTO-ZBS powders), then the powders were wet mixed for 24 hours. The CCTO-ZBS mixtures were dried overnight, compacted at 300 MPa using hydraulic pressure of 6 to 9 mm diameter and 1 to 2 mm thickness (for dielectric properties test) and at 200 MPa of 50 mm diameter and 3 mm thickness (for dielectric breakdown strength test), then sintered at 1040 °C for 10 hours using an electrical carbolite furnace. The addition of a small amount of ZBS glass about 1 wt% was able to increase the dielectric constants (33.99%) and reduce the dielectric loss (5.14%) of CCTO measured at 1 MHz. This addition has also increased the relative density to the maximum value (95.90%), helped the formation of single phase of CCTO, increased the grain size (0.35%) and reduced the porosity as compared to pure CCTO. Meanwhile the dielectric breakdown strength (58.0%) and volumetric energy storage density (80.9%) has also improved with 7 wt% of ZBS glass addition.
Production and application of thermostable protease 50a as liquid protein stain remover
Authors: Ibrahim Noor Azlina , Ibrahim Normazzaliana , Lizawardi Nor Shaf Reena , Fauzi Nurul Fayyadhah Insyirah , Al-Amsyar Syed Muhammad
Published: December 2020

Proteases are important enzymes involved in many vital physiological processes and has wide potential for industrial applications. Previously, thermostable alkaline protease 50a was reported and had potential as laundry detergent additive and eco-friendly enzymatic dehairing of animal hides. Thus, exploration of this enzyme potentials’ need to be done in order to prove that it plays an important role in diverse industrial application. This study aimed to investigate the potential of the thermostable alkaline protease 50a as a protein stain remover. One formulation has been developed as liquid spray protein stain remover containing the enzyme and tested its ability to remove protein stain through washing performance. Four different types of fabric which were jersey, cotton, koshibo and crepe has been stained with blood as the protein source. Blood stain on the fabrics were then removed with four different solution; using distilled water only, distilled water with enzyme, formulated liquid spray with enzyme, and formulated liquid spray without enzyme. The formulated liquid spray with enzyme exhibited better removal bloodstains action by showing faintness of the blood stained on the fabrics after it was sprayed. The stains removal evaluation on different types of fabric with formulated liquid spray protein stain remover obtained are as followed order: crepe > jersey > cotton > koshibo. This study proved that the formulated liquid spray with addition of enzyme showed the most effective stain removal on crepe fabric.
Preliminary Investigation of Delamination Factor for Drilling Wood Plastic Composites (WPC)
Authors: Zuraik Muhammad Amirul , Sobri Sharizal Ahmad , Abdullah Nik Asmawie Nik , Hermawan Andi , Mohamed Mazlan , Shuaib Norshah Afizi
Published: December 2020

This study examines the effect of the delamination factor on wood composite drilling. Drilling is one of the most important machining operations in the manufacturing process, operating in a variety of ways to make life better every day. The preliminary experiment focuses on the implementation of three drilling strategies to determine the most appropriate for drilling composite and to identify the effect of the machining parameters of wood plastic composite (WPC) drilling. The CNC machining centre is used at the factory of the local company to assist them in the provision of certain production inputs. It is observed that the single step drill peck is the best suited strategy for drill WPC with less delamination at the entrance and exit holes compared to the other two methods, 2-peck and 4-peck drills. Hole tends to create a peel-up and to force the delamination down heavily along the hole edge when using the 4-peck process while the least peel-up pattern happens when using a single-step method. The findings also show a large amount of peel-up delamination as the feed rate increases. Therefore, the final results are also useful in understanding the relationship between the drilling parameters and the cutting experiments.
Study of Beta vulgaris (Beetroot) Extraction in Polar Solvents as Photoabsorber in Dye-Sensitized Solar Cells Application
Authors: Adenam Norfatihah Mohd , Pirdaus Nur Alfarina , Yunin Muhamad Yuzaini Azrai Mat , Azmie Ku , Wong Khairul Nizar Syazwan Wan Salihin , Adli Hasyiya Karimah , Salleh Hasiah
Published: December 2020

Over the last two centuries, energy needs have increased substantially until non-renewable resources nearly come to depletion. Therefore, the application of renewable energy resources like solar energy is absolutely appointed favorable due to its economical impact and improved technology. Dye-sensitized solar cell (DSSC) being the type of solar cell that utilize dye as light sensitizer for the operation and become the best alternative rather than toxic chemical dyes. Betalains is one of the pigment of natural dyes that can be extracted from fruit and vegetables which majorly available in beetroot (Beta vulgaris). To get the pigment for solar cell application, the optimum extraction is crucial. Hence, in this study, several polar solvents such as distilled water, methanol, ethanol, isopropanol, n-butanol, formic acid and acetic acid were used to extract betalain pigment from Beta vulgaris (BV). Then, several characterizations were carried out to analyze the photoabsorber properties using Ultraviolet-visible Spectroscopy (UV-Vis), Fourier-Transform Infrared Spectroscopy (FTIR), High Performance Liquid Chromatography (HPLC) and Scanning Electron Microscopy (SEM). The energy bandgap of BV in different solvents (ITO/TiO2/BV) are 2.19, 2.35, 2.65, 2.73, 2.78, 2.98 and 3.00 eV for methanol, n-butanol, formic acid, ethanol, acetic acid, water and isopropanol respectively. Whilst, FTIR spectrum shows the presence of functional group of O-H, C=O and C-O-C and HPLC analysis depicted the existence of betacyanin pigment all in samples. SEM images show the presence of porous structure of TiO2 and irregular pits formed due to the formation of BV layer on TiO2. In conclusion, overall findings suggested that methanol is the best solvent for extraction of betalain pigment, answering it has best photoabsorber properties among the sample series. Further detailed study is recommended to maximise the potential of Beta vulgaris pigment as photoabsorber in DSSC application.
Effects of Styrene Butadiene Rubber on Physical and Mechanical Properties of Kenaf Core Fiber Reinforced Polypropylene Composites
Authors: Mohd Siti Hajar , Bakar Mohamad Bashree Abu , Rosdi Nik Aida Hamizah Nik , Sabri Intan Najihah , Amini Mohamad Hazim Mohd , Nordin Razif Muhammed , Intapun Jutharat
Published: December 2020

In this research, the kenaf core fiber (KCF) reinforced polypropylene (PP) in the presence of styrene butadiene rubber (SBR) were melted blending with PP using Brabender internal mixer. The composites then fabricated using compression molding to form a sheet of PP and KCF reinforced PP (KCFPP) composites. Pure polypropylene (PP) matrix was used to serve as control whilst SBR was functionalized as impact modifier to improve the toughness properties of PP. The mechanical properties were determined by tensile test using Universal Testing Machine (UTM) according to ASTM D5803. The results show that the increment in SBR content has given an improvement in impact related properties (elongation at break) but at the expenses of strength and modulus properties.
Functional group Cinnamomum porrectum wood extractives by Fourier Transform Infrared
Authors: Omar Syazrol , Mhd Ramle Sitti Fatimah , Adenam Norfatihah Mohd , Mohammad Rawi Nurul Fazita , Che Zaudin Nurul Akmar , Abdul Hamid Zubaidah Aim , Ibrahim Nor Izaida
Published: December 2020

Extractive from Cinnamomum porrectum wood was obtained using Soxhlet extraction with five different types of solvent, which are distilled water, ethanol, acetone, chloroform, and benzene. From the result, ethanol extraction shows the highest extractives yield which are 2.692%, following by acetone (1.461%), chloroform (0.940%), benzene (0.109%) and distilled water (0.005%). Extractive make a major contribution to the characteristics of wood or non-wood species. These extractives are low-molecular weight compounds, and the different classes of extractives have different chemical behaviours. In this study, the FT-IR was used to analyse the extractive of the Cinnamomum porrectum wood with ethanol, distilled water, chloroform, benzene and acetone. From the result shows that, the analysis revealed 5 different types of functional group which are O-H stretching in presence of phenolic group, C-H stretching in presence of alkane group, C-F stretching in presence of alkyl halide group; C-O stretching in presence of aldehyde group and C=C stretching in presence of alkene group.
Effects on MAPP Compatibilizer on Mechanical Properties of Kenaf Core Fibre/Graphene Nanoplatelets reinforced Polypropylene Hybrid Composites
Authors: Sabri I.N. , Bakar M.B. Abu , Mohd S.H. , Rosdi N.A.H. Nik , Mohamed M. , Sulaiman M.A. , Masri M. N. , Chuangchote S.
Published: December 2020

Natural fibre has high potential to be used as reinforcement due to more save, greener and environmentally friendly compared to synthetic fibre. In this research, kenaf core fibre (KCF)-graphene nanoplatelets (GNP) reinforced polypropylene (PP) composites were melt blending using Brabender internal mixer and fabricated by compression moulding. This research aims to fabricate and study the effect of different amounts of MAPP on the mechanical properties of the PP/KCF/GNP composites. The difference amount of maleic anhydride grafted polypropylene (MAPP) as a compatibilizer in hybrid composite was added to enhance the mechanical properties by improving the interfacial adhesion of matrix and KCF. The pure polypropylene (PP) matrix was used as a control. The mechanical properties (tensile and flexural test) were determined using Universal Testing Machine (UTM). Overall, the results show that the presence of MAPP compatibilizer successfully enhanced the mechanical properties as a result of improvement of the fibre-matrix adhesion between the KCF and PP matrix.
The Comparison between Samarium Doped Nickel Oxide and Samarium Added Nickel Oxide on Dielectric Properties
Authors: Wan Nor Azli Jasmi WND , Mohamed JJ , Sulaiman MA
Published: December 2020

In this research, the effect of Samarium Oxide (Sm) doped (mol%) NiO as a dopant and added (wt%) in NiO as ceramic composite were investigated. The comparison of both doped and added ceramic in their dielectric properties was studied. Both electroceramic Ni(1-x)SmxO and NiSmO3 were prepared by using a solid-state reaction method. Samarium was added with five different concentrations, which are 0.01, 0.02, 0.03, 0.05, and 0.10 mol% for dopant and another five different concentrations which are 1, 2, 3, 4, and 5 wt% for addition in NiO. The XRD results show that both ceramic doped and added samples did not change the NiO cubic structure. Besides, a high concentration of Sm3+ causes the lattice parameter of NiO to increase. The dielectric behavior was observed in a frequency range of 100 to 100 000 Hz. The optimum composition for Ni(1-x)SmxO and NiSmO3 was obtained at × = 0.01 mol% and 5.0 wt% sample with highest ε° (2.4 × 104 and 9.3 × 104) respectively but at the same time, they exhibit high dielectric loss (tan δ) with value 4.9 and 10.5 respectively.
Development and Characterization of Nanoemulgel Containing Piper betle Essential Oil as Active Ingredient
Authors: Ting Teo Chai , Amat Rahim Nor Fadiana , Che Zaudin Nurul Akmar , Abdullah Nor Hakimin , Mohamad Mardawani , Shoparwe Noor Fazliani , Mhd Ramle Sitti Fatimah , Aimi Zubaidah , Abdul Hamid Zubaidah Aimi , Yusof Abdul Hafidz
Published: December 2020

This study aims to formulate and characterize a stable nanoemulgel containing Piper betle essential oil as the active ingredient for topical drug delivery. Nanoemulgel is a mixture of nanoemulsion and a gelling agent. Nanoemulsion was prepared by mixing the oil phase that containing soybean oil and Piper betle essential oil at different ratios, tween 80 as the surfactant and glycerol as the co-surfactant with the aqueous phase (distilled water). The essential oil of Piper betle was extracted by using a steam distillation method. The droplet size of nanoemulsion was in the range of 28 to 161 nm. The sizes were confirmed by dynamic light scattering method. Carbopol 940 was used as the gelling agent to increase the viscosity of the nanoemulsion and turn it into nanoemulgel. Nanoemulsion and nanoemulgel were characterised by using the Tyndall effect, spreadability test, and pH test. The pH of nanoemulgel with essential oil was in the range of 7 to 6, which is safe to be used on the skin. Nanoemulgel can be a suitable carrier for the active ingredient (essential oil) to be penetrated with ease into the skin because of its small droplets size. In conclusion, Piper betle nanoemulgel has shown great potential in helping the transdermal delivery.
Preliminary Study of the Potential Graphene Oxide as Radioactive Clinical Wastewater Adsorbability in Nuclear Medicine
Authors: Abdul Razab Mohammad Khairul Azhar , Manso Mohd Syahir , Noor An’amt Mohamed , Rozi Suhanis Mohd , Abd Latif Nur Fatin Fariha , Nizam Jaafar Khairul , Jamaludin Farakhdina
Published: December 2020

This paper reports the ability of graphene oxide (GO) as a radionuclide adsorbent material for an alternative approach in nuclear medicine radioactive waste management. Notable physicochemical properties of GO mainly consist of oxygen-containing functional groups on its basal plane and edges site in the form of epoxy, hydroxyl, and carboxyl groups, making it a promising candidate for radionuclide extraction material from aqueous solution. Herein, GO was synthesised via a simplified Hummers method. The radioactive clinical waste, which is urine, was collected right after the scanning procedure and mixed with GO in various concentrations: 1 mg/ml, 1.5 mg/ml, 2 mg/ml, 2.5 mg/ml, and 3 mg/ml. The mixture was then filtered using micropore filter paper, leaving sediments on the filter paper and wastewater residues. The radioactivity of sediment and water residue was determined by using a well counter after 3, 6, 9, and 12 hours of filtration process. The activities of the sediment and water residues were found to be decreased with increasing GO concentrations. The FESEM image revealed high agglomeration structure when the sample was treated with GO of 3 mg/ml concentration. Further analysis via EDX showed the presence of other elements in the urine, which led to its attraction to the GO-layered sheets. This analysis also confirmed the presence of oxygen-functioning group in GO that facilitated the agglomeration process and solidified the radionuclide waste.