bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of higher-order modes on ferroconvection
Authors: Kanchana C. , Vélez J. A. , Pérez L. M. , Laroze D. , Siddheshwar P. G.
Published: August 2022

Using Fourier representations, an elaborate study of regular cellular-convective and chaotic motions in a ferrofluid is made. Investigation is made on the adequacy or otherwise of the minimal mode in studying such motions. Higher-order modes are also considered by adding modes (vertical/horizontal/combined extension). For higher modes, the extensions yield a dynamical system of order greater than three. The characteristic features of extended ferromagnetic-Lorenz models are analyzed using the largest Lyapunov exponent(LE), second largest LE, bifurcation diagram, and phase-space plots. The effect of additional modes on critical modal-Rayleigh (infinitesimal and finite-amplitude ones) numbers and the Rayleigh number at which transition to chaos occurs are examined to report features of ferroconvection hitherto unseen in previous studies. As both horizontal and vertical modes are increased, our findings infer that the dynamical system displays advanced onset of regular convection and delayed chaotic motion. Vigorous-chaotic motion is seen on adding vertical modes, whereas on adding horizontal modes, intense chaos appears with decreased intensity for large values of the scaled Rayleigh number. Most important finding from the study is that as modes are increased (vertical/horizontal), the transition from regular to chaotic motion is greatly modified and leads the system to a hyper-chaotic state. Conventionally, the chaotic or hyper-chaotic state is intermittent with a periodic/quasi-periodic state but it can be retained in the chaotic or hyper-chaotic state by considering moderate values of the Prandtl number and/or by bringing in the ferromagnetic effect.
Controllable transport and size segregation of tiny particles harnessing noise in 2D Brownian motor system
Authors: Hou Chaofeng , Huang Yufeng
Published: August 2022

Controllable transport and size segregation of tiny particles following the Brownian motor mechanism are investigated with pseudo-particle modeling (PPM), a simplified molecular simulation approach, in which the liquid surrounding the Brownian particle is discretized into many pseudo particles and naturally introduces thermal noise by hard-sphere interaction between the pseudo particles. An asymmetric periodic potential is applied to the Brownian particles acting as a flashing ratchet model. The macroscopic directional motion of a single Brownian particle in external non-equilibrium fluctuation is reproduced well by the method. Illustratively, the PPM method is successfully employed to conduct the simulations of Brownian motor and testify the adaptability of the method. The segregation of different-sized particles is also studied by varying the size ratio and operation conditions, such as temperature. The simulations will help a quantitative design of Brownian motors and their application in particle transport, separation, and segregation.
Fabrication of airbridges with gradient exposure
Authors: Sun Yuting , Ding Jiayu , Xia Xiaoyu , Wang Xiaohan , Xu Jianwen , Song Shuqing , Lan Dong , Zhao Jie , Yu Yang
Published: August 2022

In superconducting quantum circuits, airbridges are critical for eliminating parasitic slotline modes of coplanar waveguide circuits and reducing crosstalks between direct current magnetic flux biases. Here, we present a technique for fabricating superconducting airbridges. With this technique, a single layer of photoresist is employed, and the gradient exposure process is used to define the profile of airbridges. In order to properly obtain the bridge profile, we design exposure dosage based on residual photoresist thickness and laser power calibrations. Compared with other airbridge fabrication techniques, the gradient exposure fabrication technique provides the ability to produce lossless superconducting airbridges with flexible size and, thus, is more suitable for large-scale superconducting quantum circuits. Furthermore, this method reduces the complexity of the fabrication process and provides a high fabrication yield.
Microgap breakdown with floating metal rod perturbations
Authors: Chen Jiandong , Verboncoeur John P. , Fu Yangyang
Published: August 2022

We report the characterization of microgap breakdown with perturbations from a metal rod floating between anode and cathode electrodes. The effects of the metal rod on the electric field distribution and the field enhancement factor are evaluated by numerical simulation and the conformal mapping method, and they indicate that the field emission regime is not reached. The breakdown voltages in the Townsend discharge regime are determined based on the voltage–current characteristics, which are obtained from two-dimensional fluid simulations. It is found that the breakdown characteristics can be significantly modulated by the floating metal rod, and the breakdown curve (breakdown voltage vs the net gap distance) is no longer U-shaped, which deviates from the conventional Paschen's law. The underlying physical mechanisms are related to the electric field enhancement, curved breakdown path, and nonuniform ion flux caused by the electric shielding effect. The results provide insights into breakdown characteristics in microscale discharges, which may promote conventional investigation of simplified clean gaps toward more complex conditions (e.g., with floating microparticles) in miniaturized plasma devices.
Water filling of microcavities
Authors: Shen Feng , Zhu Lin , Chen Jie , Liu Zhaomiao
Published: August 2022

Cavity-filling is a common phenomenon whereby a fluid fills all or part of a cavity, displacing another immiscible fluid. In this study, we experimentally and theoretically investigate the effects of the cavity aspect ratio, channel width, tilting angle of the cavity leading wall, and inlet flow rate on the morphology of the water-air interface and the filling fraction of various cavities. Considering the influencing factors, we derive two formulas for predicting the filling fraction, and verify these expressions against experimental results. The findings of this study provide theoretical guidance for applications related to pressure-driven filling of cavity structures.
Talking with strangers is surprisingly informative
Authors: Atir Stav , Wald Kristina A. , Epley Nicholas
Published: August 2022

A meaningful amount of people’s knowledge comes from their conversations with others. The amount people expect to learn predicts their interest in having a conversation (pretests 1 and 2), suggesting that the presumed information value of conversations guides decisions of whom to talk with. The results of seven experiments, however, suggest that people may systematically underestimate the informational benefit of conversation, creating a barrier to talking with—and hence learning from—others in daily life. Participants who were asked to talk with another person expected to learn significantly less from the conversation than they actually reported learning afterward, regardless of whether they had conversation prompts and whether they had the goal to learn (experiments 1 and 2). Undervaluing conversation does not stem from having systematically poor opinions of how much others know (experiment 3) but is instead related to the inherent uncertainty involved in conversation itself. Consequently, people underestimate learning to a lesser extent when uncertainty is reduced, as in a nonsocial context (surfing the web, experiment 4); when talking to an acquainted conversation partner (experiment 5); and after knowing the content of the conversation (experiment 6). Underestimating learning in conversation is distinct from underestimating other positive qualities in conversation, such as enjoyment (experiment 7). Misunderstanding how much can be learned in conversation could keep people from learning from others in daily life.
Jahn–Taller distortion on exchange interactions between cations in Mn
x
Cu1−x
Co2O4 system
Authors: Xu Lei , Zhen Congmian , Shui Zizhou , Xu Dayin , Liu Lu , Ma Li , Zhao Dewei , Hou Denglu
Published: August 2022

Pure-phase Mn
x
Cu1−x
Co2O4 (x = 0, 0.25, 0.5, 0.75 and 1) polycrystalline powders were prepared by using a low-temperature solid-phase reaction method. With doping Mn ion into the octahedral sites, the unit cell transforms from cubic phase to tetragonal phase, and the octahedral Co3+ ions move to the tetrahedral sites and become high spin Co2+ ions. When the doped Mn concentration is low, the sample is dominated by antiferromagnetic (AFM) interactions between tetrahedral Cu2+. As the Mn concentration increases, ferrimagnetic interactions between tetrahedral Co2+ and octahedral Mn3+ can be observed. When the Mn concentration is high enough, due to strong Jahn–Taller distortion, the e
g energy level of Mn splits, which weakens the interactions between the tetrahedral and the octahedral cations, and enhances interactions between the octahedral cations. Ferromagnetic interactions between octahedral Mn3+ and AFM interactions between octahedral Mn2+ become obvious. The magnetic ordering temperature has been raised from 20 K to 93 K as the Mn concentration increases, and the maximum exchange bias field is observed to be 1.063 kOe.
MOVPE-grown GaN/AlGaN heterostructures on sapphire with polarization-induced two-dimensional hole gases
Authors: Beckmann Carsten , Wieben Jens , Zweipfennig Thorsten , Kirchbrücher Arno , Ehrler Jasmin , Stamm Robert , Yang Zineng , Kalisch Holger , Vescan Andrei
Published: August 2022

GaN/Al
x
Ga1−x
N heterostructures were grown by metal-organic vapor phase epitaxy to study in detail the formation of two-dimensional hole gases (2DHG). In contrast to the common double-heterostructure approach to create 2DHG, which is based on GaN buffer layers and leads to the parallel formation of a two-dimensional electron gas, this concept is designed to create a 2DHG only. The Al mole fraction in the AlGaN buffer and the GaN channel thickness are each varied to investigate their influence on 2DHG properties. The carrier concentrations as determined by room temperature Hall measurements follow the expected trend given by the Al content dependence of the spontaneous polarization of the relaxed AlGaN buffer. A 2DHG density as high as of 1.6 × 1013 cm−2 with a negligible dependence on temperature (80–300 K) is determined for a GaN/Al0.29Ga0.71N heterostructure by temperature-dependent Hall measurements. Higher carrier concentrations can also be achieved, yet strain relaxation of the GaN channel degrades the transport properties for Al contents above 30%.
The effect of antisite disorder on magnetic and exchange bias properties of Gd-substituted Y2CoMnO6 double perovskite
Authors: Khan Anasua , Rajput Sarita , Anas M , Malik V K , Maitra T , Nath T K , Taraphder A
Published: August 2022

Combining experimental investigations and first-principles density functional theory (DFT) calculations, we report physical and magnetic properties of Gd-substituted Y2CoMnO6 double perovskite, which are strongly influenced by antisite-disorder-driven spin configurations. On Gd doping, Co and Mn ions are present in mixed-valence (Co3+, Co2+, Mn3+ and Mn4+) states. Multiple magnetic transitions have been observed: (i) paramagnetic to ferromagnetic transition is found to occur at T

C
= 95.5 K, (ii) antiferromagnetic transition at T

N
= 47 K is driven by

3
d

−

4
f

polarization and antisite disorder present in the sample, (iii) change in magnetization below T

⩽

20 K, primarily originating from Gd ordering, as revealed from our DFT calculations. AC susceptibility measurement confirms the absence of any spin-glass or cluster-glass phases in this material. A significantly large exchange bias effect (H

E
B

= 1.07 kOe) is found to occur below 47 K due to interfaces of FM and AFM clusters created by antisite-disorder.
Stochastic and a posteriori optimization to mitigate coil manufacturing errors in stellarator design
Authors: Wechsung Florian , Giuliani Andrew , Landreman Matt , Cerfon Antoine , Stadler Georg
Published: August 2022

It was recently shown in Wechsung et al (2022 Proc. Natl Acad. Sci. USA
119 e2202084119) that there exist electromagnetic coils that generate magnetic fields, which are excellent approximations to quasi-symmetric fields and have very good particle confinement properties. Using a Gaussian process-based model for coil perturbations, we investigate the impact of manufacturing errors on the performance of these coils. We show that even fairly small errors result in noticeable performance degradation. While stochastic optimization yields minor improvements, it is not possible to mitigate these errors significantly. As an alternative to stochastic optimization, we then formulate a new optimization problem for computing optimal adjustments of the coil positions and currents without changing the shapes of the coil. These a-posteriori adjustments are able to reduce the impact of coil errors by an order of magnitude, providing a new perspective for dealing with manufacturing tolerances in stellarator design.
Nonplanar ion-acoustic solitons and shocks with superthermal trapped electrons and transverse perturbations
Authors: Jahangir R , Ali S
Published: August 2022

The formation and propagation of nonlinear ion-acoustic (IA) waves are studied in an unmagnetized cold viscous plasma, comprising the inertial ions and superthermal trapped electrons in cylindrical geometry with transverse perturbations. The well-known reductive perturbation method is employed to derive cylindrical trapped Kadomtsev Petviashvili Burgers (CTKPB) and cylindrical trapped Kadomtsev Petviashvili (CTKP) equations with and without dissipation effects, respectively. The exact solutions of CTKPB and CTKP equations are obtained for the first time by utilizing the dependent variable transformation. The soliton and shock structures are found to be significantly affected by the plasma parameters including the trapping efficiency parameter β, the superthermality parameter κ, viscosity µ
0 and the geometrical effects. Importantly, the geometrical effects and transverse perturbations alter the shape of solitons and shocks, resulting into the parabolic nonlinear structures. These structures become more parabolic at later times due to an interplay of transverse and time coordinates (η, τ). The results of the present study might be helpful to understand the characteristics of IA structures in space plasmas, such as auroral regions, where energetic trapped electrons have been observed.
Preparation and operating characteristics analysis of high-speed iron phthalocyanine organic phototriode
Authors: Feng Gaoxu , Zhu Min , Ge Qicai , Gao Xiaoting , Zhao Yan
Published: August 2022

The structure of Cu/FePc/Al/FePc/Cu vertical structure organic bipolar junction triode (VOBJT) is prepared by vacuum vapour deposition and magnetron sputtering process, using the photosensitive organic semiconductor material iron phthalocyanine (FePc) as the organic layer. The experiment results show that the device’s output current is unsaturated, and the base voltage can effectively regulate the output current. FePc-VOBJT has good optoelectronic characteristics, and the optical response rate can reach R = 0.19 A W−1. Under the AC base voltage, the cut-off frequency of FePc-VOBJT is f
c = 10.7 kHz, and the turn-on and turn-off time can reach the microsecond level. When FePc-VOBJT responds to light pulse, the cut-off frequency f
c(Light) = 2 kHz, and the switch time can reach the millisecond level. Vertical structure dramatically reduces the device’s conductive channel length and junction capacitance, which makes the organic semiconductor materials with poor electrical properties expected to be used in high-speed photoelectric sensors.
Linear displacement and force characterisation of a 3D-printed flexure-based delta actuator
Authors: Chen Xu , Kiziroglou Michail E , Yeatman Eric M
Published: August 2022

Piezoelectric beams provide a fast, high-force and scalable actuation mechanism that could offer precise motion control to medical microdevices including invasive micromanipulators, catheters and diagnosis tools. Their small displacement range can be addressed by motion amplification mechanisms. In this paper, a piezoelectric-actuated delta-robot actuator is proposed for probe-based confocal laser endomicroscopy (pCLE) microsystems. A prototype is designed and fabricated using three-dimensional (3D) polymer compound printing for a multi-flexure compliant motion amplifier and commercial piezoelectric beams. The flexure material is optimised for maximum linear output motion. The overall robot length is 76 mm and its maximum lateral dimension is 32 mm, with 10 g overall mass, including three piezoelectric beams. An axial motion control range of 0.70 mm and a maximum axial force of 20 mN are demonstrated, at 140 V actuation voltage. The proposed actuator architecture is promising for controlling lens, fibre and micromanipulator components for medical microrobotic applications.
Basis for time crystal phenomena in ultra-cold atoms bouncing on an oscillating mirror
Authors: Golletz Weronika , Czarnecki Andrzej , Sacha Krzysztof , Kuroś Arkadiusz
Published: August 2022

We consider classical dynamics of a one-dimensional system of N particles bouncing on an oscillating mirror in the presence of gravitational field. The particles behave like hard balls and they are resonantly driven by the mirror. We identify the manifolds the particles move on and derive the effective secular Hamiltonian for resonant motion of the particles. Proper choice of time periodic oscillations of the mirror allows for engineering of the effective behaviour of the particles. In particular, the system can behave like an N-dimensional fictitious particle moving in an N-dimensional crystalline structure. Our classical analysis constitutes a basis for quantum research of novel time crystal phenomena in ultra-cold atoms bouncing on an oscillating atom mirror.
Optical spectra of zigzag graphene nanoribbons: a first-principles study
Authors: Mousavi Seyedeh Tahereh , Badehian Hojat Allah , Gharbavi Khadijeh
Published: August 2022

The electrical and optical properties of zigzag graphene nanoribbons is simulated using Density Functional Theory (DFT). It is found that n-ZGNRs (n = 18, 22, 26, 30) have metallic behavior. The results reveal that when the nanoribbon width increases, the first optical bandgap and optical absorption peaks diminish. Furthermore, at energies greater than around 1.40 eV, n-ZGNRs (n = 18, 22, 26, 30) have a negative refractive index for the z polarization. The maximum optical reflection peaks of n-ZGNRs (n = 18, 22, 26, 30) occur at about 5 eV for y polarization. Furthermore, unlike the y polarization, the z components of optical reflectivity are positioned at lower energies. The results show that the optical extinction of the simulated ZGNRs increases with ribbon width. The main reason is that the larger supercells have a higher mass density. For

E

y

 ∼ 0–4.50 eV, n-ZGNRs (n = 18, 22, 26, 30) support the conditions for the transverse-electric (TE) mode. Additionally, for

E

y

higher than around 4.50 eV, n-ZGNRs (n = 18, 22, 26, 30) supplies the transverse-magnetic (TM) plasmons.
Magnetic properties and magnetocaloric effects of Tm1–x
Er
x
CuAl (x = 0.25, 0.5, and 0.75) compounds
Authors: Sun Hao , Wang Junfeng , Tian Lu , Gong Jianjian , Mo Zhaojun , Shen Jun , Shen Baogen
Published: August 2022

We investigate the structural, magnetic, and magnetocaloric effects (MCE) of Tm1−x
Er
x
CuAl (x = 0.25, 0.5, and 0.75) compounds. The compounds undergo a second-order phase transition originating from the ferromagnetic to paramagnetic transition around 3.2 K, 5 K, and 6 K, respectively. The maximum magnetic entropy changes (

−
Δ

S
M

max

) of Tm1−x
Er
x
CuAl (x = 0.25, 0.5, and 0.75) are 17.1 J⋅kg−1⋅K−1, 18.1 J⋅kg−1⋅K−1, and 17.5 J⋅kg−1⋅K−1 under the magnetic field in the range of 0–2 T, with the corresponding refrigerant capacity (RC) values of 131 J⋅kg−1, 136 J⋅kg−1, and 126 J⋅kg−1, respectively. The increase of

−
Δ

S
M

max

for Tm0.5Er0.5CuAl may be relevant to the change of magnetic moment distribution of Er and stress coming from element substitution. This work provides several compounds that can enrich the family of giant MCE materials in the cryogenic region.
Acoustic propagation uncertainty in internal wave environments using an ocean-acoustic joint model
Authors: Gao Fei , Xu Fanghua , Li Zhenglin , Qin Jixing , Zhang Qinya
Published: August 2022

An ocean-acoustic joint model is developed for research of acoustic propagation uncertainty in internal wave environments. The internal waves are numerically produced by tidal forcing over a continental slope using an ocean model. Three parameters (i.e., internal wave, source depth, and water depth) contribute to the dynamic waveguide environments, and result in stochastic sound fields. The sensitivity of the transmission loss (TL) to environment parameters, statistical characteristics of the TL variation, and the associated physical mechanisms are investigated by the Sobol sensitivity analysis method, the Monte Carlo sampling, and the coupled normal mode theory, respectively. The results show that the TL is most sensitive to the source depth in the near field, resulted from the initial amplitudes of higher-order modes; while in middle and far fields, the internal waves are responsible for more than 80% of the total acoustic propagation contribution. In addition, the standard deviation of the TL in the near field and the shallow layer is smaller than those in the middle and far fields and the deep layer.
Photoreflectance system based on vacuum ultraviolet laser at 177.3 nm
Authors: Luo Wei-Xia , Liu Xue-Lu , Luo Xiang-Dong , Yang Feng , Zhang Shen-Jin , Peng Qin-Jun , Xu Zu-Yan , Tan Ping-Heng
Published: August 2022

Photoreflectance (PR) spectroscopy is a powerful and non-destructive experimental technique to explore interband transitions of semiconductors. In most PR systems, the photon energy of the pumping beam is usually chosen to be higher than the bandgap energy of the sample. To the best of our knowledge, the highest energy of pumping laser in reported PR systems is 5.08 eV (244 nm), not yet in the vacuum ultraviolet (VUV) region. In this work, we report the design and construction of a PR system pumped by VUV laser of 7.0 eV (177.3 nm). At the same time, dual-modulated technique is applied and a dual channel lock-in-amplifier is integrated into the system for efficient PR measurement. The system’s performance is verified by the PR spectroscopy measurement of well-studied semiconductors, which testifies its ability to probe critical-point energies of the electronic band in semiconductors from ultraviolet to near-infrared spectral region.
Realization of the iSWAP-like gate among the superconducting qutrits
Authors: Xu Peng , Zhang Ran , Zhao Sheng-Mei
Published: August 2022

High-dimensional quantum systems, such as qutrits (quantum three-level systems), have multiple accessible energy levels beyond the two-level qubits. Therefore, qutrits can offer a larger state space to improve the efficiency of quantum computation. Here, we demonstrate a high-fidelity iSWAP-like gate operation on a frequency-tunable superconducting qutrits system. The superconducting quantum system consists of two qutrits that are coupled via a resonator with fixed qutrit-resonator coupling strengths. Through designing the frequency pulse profile and optimizing the parameter values, the gate error can be suppressed below 1.5 × 10−3. To bear out the feasibility of the proposal, we have conducted our study with experimentally accessible parameters. As the resonator can mediate the interaction between the irrelevant qutrits, the presented approach can also be used to couple multiple qutrits together, providing a good platform for quantum information processing.
Simulation of ozone concentrations inside 60CO industrial irradiator
Authors: Noaman Ali , El gamel Amal A.
Published: August 2022

The motivation of this work is to study the relationship between gamma radiation and also ozone concentration in 60CO industrial irradiators. Because ozone is considered to be one of the most important safety issues, because it has a destructive effect on the human body and has a corrosive effect on metal parts in the irradiated area. Moreover, due to its high reactivity. So first using ozone monogram method to measure ozone concentration, and also the effect of the factor on ozone concentration was determined. MATLAB computer code was used to calculate the ozone concentration-response with completely different statistics. Among them, ozone concentration in the 60CO irradiation area is in a completely different state. These conditions include: different gamma emitters, completely different irradiators, airflow correction, and engine failure. It is suggested that ozone formation may be a direct effect of gamma radiations. the result show also that the health hazards due to the ozone produced during irradiation are significant and should not be overlooked. It was observed that in case of 1Ci motor failure, the detection time is 67.5 minutes. While, for 0.1Ci motor failure, the detection time is 32.2 minutes. To fulfill the employee safety limits. it is recommended to have a second control system with ventilation
Study Matrix Densities Variation on Assay of 137Cs & 60Co using Gamma Spectrometric Analysis and Correction Equation
Authors: Omar Omar Abo-Bakr , El-mongy Sayed A.
Published: August 2022

There are many factors affecting the results of specific activity determination by using HPGe detection system. One of these important factors is the incompatibility and dissimilarity between the density of the certified standard source for efficiency calibration of the system and the samples to be measured. In this work, five standard samples containing 137Cs at 661.6 keV and 60Co at 1173.2and 1332.5 keV energies, with the same geometry and different densities were used to investigate and validate the percentage of error. It is scientifically known that the low energies are attenuated more than the high energies. The densities of the used standard samples are 0.7, 1, 1.2, 1.3, 1.6 g/cm3 respectively. The detection system was well calibrated before carrying out the measurements. The calculated error percentages between the measured activities (in Bq) and the certified values for 137Cs and 60Co in the standard samples were found to be in wide range from 9.8% to 19.2% for 137Cs and from 7.77% to 16.1% for 60Co respectively. A correction equation taking into consideration the densities variation was suggested and formulated to overcome and compensate these errors.
Radionuclide Content and Radiation Dose Rates of Uraniferous and Mineralized Granites at GV Occurrence in Gabal Gattar, Northeastern Desert, Egypt.
Authors: Abdelwahab F M , El Gendy N H , Barakat M Kh , Mohamed M S , El-Tohamy A M , El Terb R A , El Feky M G
Published: August 2022

G. Gattar is located in the northern part of the Eastern Desert of Egypt, bounded by latitudes 26° 52´ - 27° 08´ N and longitudes 33° 13´ – 33° 26´ E and covers an area of about 178 km2. Eighteen samples, nine from uraniferous and nine from mineralized granites were measured radiometrically for 238U, 232Th, 226RaeU and 40K determination by Na-I detector and the radioactive minerals identified by alpha track method. Based on the petrography, radioactive mineral content and radioactivity, Gattarian granites were classified into uraniferous and mineralized granites. Uranium contents reach up to 229 ppm in the uraniferous granites and to 20300 ppm in the mineralized granites, which is extremely higher than the international limits. eTh/eU ratio of the studied uraniferous and mineralized granites show average ratios of 0.05 and 0.0044, respectively, which is extremely lower than the average of igneous rocks, suggesting uranium enrichment in reducing conditions. The uraniferous and mineralized granites U/Th ratios average are 62.23 and 4234.45, respectively, indicating that the studied two granitic types are considered highly productive rocks. The radioelements interrelations manifest that the distribution of radioelements not only magmatic but also related to hydrothermal redistribution of radionuclides associating with uranium deposition. The radiological hazard parameters, such as the dose rate (D), the annual effective dose equivalent (AEDE), radium equivalent activity (Raeq), external (Hex), internal (Hin) hazard indices and gamma index (Iγ) were estimated for these granites and compared with the international levels. Nearly, all the studied samples are to a great extent higher than the recommended permissible levels for all environmental parameters.
Isotopic Ratio of Radionuclides in Natural Materials
Authors: Mubarak Fawzia , Ali Abdallah
Published: August 2022

In this work, the 235U/238U ratio and 235U concentration were discussed. 235,238 U isotopes were measured and calculated for uranium mines samples and reference material. The difference and deviation in experimental and calculated values for 235U were discussed. It can be concluded that the 235U/238U ratio was varied naturally with a range of 0.0442 to 0.0478. The measured ratio was deviated upon the reference value (0.0462) with a range of -0.02% to 1.5%, as we can conclude that the measured values were very accurate. While the values of the calculated ratio were varied from -0.089% up to 17%, which represents low accuracy. Isotopic uranium ratio changes over time depending on spontaneous fission half-life, radioactive decay rate and gamma-ray intensity for 235,238U. These fractions in uranium isotopic were discussed and here we assume a tool for correction and normalization. It can be concluded that the 235U/238U ratio and 235Uconcentration can be varied naturally with a slight deviation. The difference and reliability of 235,238U isotope on experimental results of uranium mines depend on several reasons such as decay rate of natural uranium, Spontaneous fission half-life and Gamma-ray intensity for 235,238U. Therefore, the experimental results for 235U are very accurate than the calculated results to improve the isotopes of U and 235U/238U ratio in Uranium mines.
Process simulation and optimization of dodecyl benzene sulfonic acid production plant
Authors: Mohamed Ahmed Fathy , Azim Ibrahim El Sayed Waleed Abd El , Moneim Nabil Abdel , Sorour Faisal Hassan
Published: August 2022

The aim of work is to design sulfonating plant on the basis of a hydrophilic sulfonate head-group and a hydrophobic alkyl benzene tail-group reaction mechanism, study of kinetics and thermodynamics followed by a steady-state simulation for the process was done by ASPEN HYSYS (V8.8) through using Peng-Robinson fluid package. Then heat integration of the process, done by using Aspen Energy Analyzer and studies of the influence parameters on the simulated process of dodecyl benzene sulfonic acid. Alkyl benzene sulphonate is produced due to the sulphonation reaction of an alkylbenzene (LAB) plus a sulphonating agent in a falling film sulphonator to produce sulfonic acid (LABSA).The modeling of dodecyl benzene sulfonic acid plant depends on : Air drying, Sulphur melting and proportioning, Sulphur combustion and SO3 production, Film sulfonation. Dodecyl benzene sulfonic acid production rate is influenced by changing of the following factors: the sulfur molar flow rate, molar flow rate of air and pressure of dodecyl benzene, the results of optimization shows that : The optimum operating Molar flow rate of sulfur is lies in the range of [3:3.5] Kg.mol/h, The optimum operating Molar flow rate of Air is 25 Kg.mol/h, The optimum operating Molar flow rate of Dodecyl Benzene is 3.1 Kg.mol/h and The optimum operating Pressure of Dodecyl Benzene is 70 KPa. For heat integration, a proposed heat exchanger network is generated which made the process functional without external heating. Generation of the top 10 heat exchanger network (HEN) leads to: the best case scenario from the top 10 scenarios from the point of cost and also from the point of cooling and heating required was design (9). After heat integration, the total amount of cooling demand decreased from 912620.50 KJ/h to 890261.56 KJ/h and the total amount of heating demand decreased from 22358.94 KJ/h to 0KJ/h.
A Mini-Review on Recent Developments in Metal-Organic-Frameworks (MOFs) Derived Carbon as A Microwave Absorption Materials (MAMs)
Authors: Elmowafy Mohamed E. , Abuzalat Osama , Tantawy Hesham , Elsayed Mohamed A.
Published: August 2022

As a result of its ability to reduce electromagnetic waves (EMW), microwave absorption materials (MAMs) have gained a lot of interest recently. Thermal or other sources of energy can be used to disperse EMW. Ideal MAMs have many loss processes and must be light, thin, absorb a wide range of frequencies, and have high absorption capabilities. Because of the high concentration of electromagnetic radiation in our surroundings that are detrimental to people, MAMs (microwave absorption materials) are a hot issue. Radar stealth is further aided by MAMs, which are used to hide weaponry. Nanomaterials have been tested as MAMs, however, not all of them have worked out. In this study, we hope to shed light on the design and manufacturing of MOF-derived Carbon-based MAMs, along with their basics and applications.
High Performance Sheet of PBX based on NTO
Authors: Elbeih Ahmed , Elnogomy Mohamed , Elshenawy Tamer , Saleh Ahmed , Azazy Ahmed , Hussein Ahmed k. , Zaky M. G. , Ahmed Hesham S.
Published: August 2022

3-nitro-1,2,4-triazol-5-one (NTO) is a low sensitive high explosive which has been used in the formation of low sensitive ammunitions. In this study, the preparation method of NTO explosive was discussed. A sheet of PBX on the basis of NTO bonded by HTPB binder matrix was prepared (NTO-PBX). The formulation is investigated for explosive properties to understand the influence of NTO on the performance of the PBX sheet. Impact and friction sensitivities of NTO-PBX, heat of Combustion and Detonation velocity were specified. EXPLO5 code, version 5.04, was utilized to calculate the theoretical detonation characteristics of NTO-PBX. For comparison, Data-sheetC, EPX-1, Semtex 1A and Formex P1, were also studied. By comparing the obtained results, confirmation of some relationships was investigated. The detonation velocity of the NTO sheet explosive was the highest of all the studied samples. The experimental and calculated results of NTO-PBX and the other compositions are in a good agreement.
A Novel Approach for Synthesis of Low Sensitive FOX-7 with a high % yield
Authors: Abdelhafiz Mahmoud , Mostafa Hosam E.
Published: August 2022

Attaining a high performance is one of the most seeking demands in the energetic materials field. However, achieving that goal while keeping a high level of safety became a serious puzzle. 1,1-diamino-2,2-dinitroethene (FOX-7) could be a promising candidate to solve that issue regarding its favorable explosive characteristics together with its low vulnerability. However, its high cost and low yield obtained via the FOI method limit its use in the field of insensitive munition (IM). In this work, we propose a novel approach to synthesis the FOX-7 crystals with high purity, a relatively high yield, and an extremely low impact, friction, ignition sensitivities. The obtained crystals were characterized using FTIR Spectroscopy, Proton NMR Spectroscopy, IKA impact test apparatus, BAM friction test apparatus, Chilworth deflagration test apparatus, and the adiabatic calorific bomb. Results confirmed the successful preparation of pure FOX-7 crystals with a promising yield of 64%, in comparison to the yield of the FOI method of 55%, and extremely low sensitivities using our proposed approach.
Process Engineering Design of Tobacco wastes Incinerator with Utilization of Heat Energy from Combustion Gases
Authors: Elmansy Asmaa , Abdelmonem N. , Shaaban Ahmed , Abdelghany Amr
Published: August 2022

An integrated incineration unit was developed to handle tobacco waste within a processing plant in the Eastern Company, Egypt. In addition to the unit, subsequent utilization of the heat content of combustion gases was investigated. The incinerator design was tailored around the current process of solid waste combustion within the tobacco processing plants of the Eastern Company in 6th October City, Egypt. A feeding rate of 1 ton/hr of solid waste consisted of 50% mass of tobacco, 20% paper, and cartons, 20% wooden boxes, and 10% plastics. The volume occupied by the remaining ash after the incineration process would not exceed 5% of the feedstock. The overall material and energy balances were calculated based on a 25490 kg/hr combustion gas discharge with a heat content of 20.09 Gj/hr. Energy from flue gases would be utilized to generate saturated steam or produce hot water. The design included a fired-tube boiler capable of generating 7 ton/hr saturated steam at 185 °C and 10 bar. The temperature of the exhaust effluent combustion gases vented into the atmosphere had to stand at 200 °C to avoid penalties. Moreover, this effluent temperature is considered to be effective and efficient utilization of the heat content in the waste.
Compendium data and preliminary results based on alum sludge and gravel continuous fixed-packed-bed column substrate as sustainable practice for constructed wetland development in northern Egypt
Authors: Tony Maha A.
Published: August 2022

The present investigation represents the valuable reclaims of the aluminum-based waterworks sludge that is so called “alum sludge” to close the loop concerning the sludge waste production and the sustainable ecosystem. In this study the adsorption behaviors of aluminium based sludge, namely alum sludge (AS) and gravel as cost-efficient adsorbents regarding dye elimination from aqueous synthetic stream were analyzed in fixed bed column. The influence of variable boundaries such as column pack depth and influent concentration on the effluent concentrations via breakthrough curves were examined. It is estimated that the removal uptake and sorption capabilities elevated as the initial influent loading of the dye dismissed for the fixed bed height of the both adsorbents, namely, gravel and AS. Thereafter, a preliminarily results were checked to investigate the feasibility of the adsorption column in Reactive Blue 4 (RB4) adsorption. The maximum adsorption capacities were observed around 4 mg L-1 for sample with pH 7.5 that is signified as the natural pH of the synthetic stream. However, increasing the initial dye loading increasing the adsorption capacity which reached to 5.5 mg L-1 for the dye loading 27.8 mg L-$$$1 of Reactive Blue 4 (RB4). Thus, the first results will be a valued scheme in the development of adsorption systems to build up a constructed wetland facility.
Using biochar to control nitric oxide air pollution
Authors: Mohamed Ghada Osama , Saleh Maher Elsayed , Shalaby Elsayed Ahmed , Elsafty Ahmed Samir
Published: August 2022

This study deals with the ability of Rice Husk Biochar (RHB) to adsorb and reduce the concentration of 90 ppm Nitric Oxide (NO) gas which passed through it with a 1.2 liter/min flow rate within 8 minutes. The characteristics of biochar before and after adsorption were studied by SEM, EDAX, and FTIR analyses. To study the effect of different factors on adsorption the effect of manufacturing temperatures of biochar was studied by using two degrees 450 °C and 500 °C. It has also been measured the effect of biochar particles size using two types of size, coarse (C) and fine (F). The effect of the shape of the measurement system on the adsorption was also measured using two types of systems A and B. In general, the RHB450C A gives the best adsorption capacity for NO (95.7 mg/g) followed by RHB450F A (41.9 mg/g) followed by RHB500C A (24.8 mg/g). Both Langmuir and Freundlich isothermal models were applied to mathematical modelling of NO adsorption, and based on the coefficient of determination (r2) Langmuir’s model provided a perfect fit to the experimental data. It was also found that the pseudo-first-order model is suitable for studying adsorption kinetics.
Air pollution remediation using synergetic coupling of AC/TiO2 filter for benzene gas removal: regeneration and reuse of spent activated carbon after the treatment process
Authors: Mohamed E. F.
Published: August 2022

Recently, climate change and air pollution are of the most important problems confronting the world. Hence, the present work is designed to provide an air purifier that can be re-utilized many times with high efficiency for several volatile pollutants. The air purifier fabricated from AC/TiO2 was used to investigate the performance of this filter towards the removal of volatile organic compounds (VOCs) from the air. The filter was composed of a mixture of fiber layers (TiO2, SiO2 and AC). The results indicated that the synergistic coupling of adsorption/oxidation technique is effective for removal of the air pollutants as well as for regeneration of the activated carbon to be extensional reused. The performance test of air purifier confirmed its high removal efficiency (98%). It was found that nearly up to 94% and 86% recovery of the filter activity could be achieved after the second and third cycles of treatment, respectively. From these results, AC/TiO2 filter still has the capability to remove and control extra gas pollutants indicating the synergistic coupling effect of TiO2 with the activated carbon. This filter concerns in developing an economic and feasible air purifier system to remove air contaminants for several times.
Multivariate-Parameters Effect of Dewatered Aluminium-Based Sludge in Catalytic Oxidation into Wastewater Treatment with A Special Strategy for Solar Energy Application
Authors: Thabet Rahma H. , Fouad Mai K. , El Sherbiny Shakinaz A. , Tony Maha A.
Published: August 2022

In this study, the Fenton/adsorption of dye effluent containing Levafix blue dye has been carried out via a cost-efficient and eco-friendly heterogeneous Fenton and solar-Fenton methods. Alum sludge, the water treatment by-product were successfully collected and calcined to 400 °C (AS400) were tested for use as a catalyst in the Fenton process. X-ray diffraction, Scanned electron microscopy techniques were applied to investigate the structural and morphological properties of such catalyst. The results showed that the material had a better photocatalytic activity under sunlight irradiation. The process of solar photo-Fenton reagent including AS400 was found to be competent for the oxidation of Levafix dye compared with the process of using Fenton process. The oxidation was improved to a great extent from 60 to 99% removal in the treatment time of 40-min irradiation. The key factor is containing 1.5 g/L and 800 mg/L of AS400 and H2O2, respectively, at pH 3.0. As a result, the practical application of such a by-product as a catalyst on the Fenton system employing natural solar radiation on the treating dye effluent indicates that technique is extremely efficient for a safer environment.
Surface electronic structure of possible high-Tc
surface superconductor WO3 based on the first-principles calculation
Authors: Sekikawa Takuya , Kawai Hiroyuki , Ōno Yoshiaki
Published: August 2022

The first-principles calculation is performed to investigate the surface electronic structure of WO3 in which high-Tc
surface superconductivity up to Tc
=120 K is observed when alkali metals are alightly doped. To take into account of the surface effect, we employ the tetragonal 14-layers slab model and find that a remarkable in-gap band with a narrow band width of 0.13 eV appears at about 0.6 eV below the conduction bands. Detailed analysis of the wave functions reveal that the in-gap band mainly consists of orbitals in the first and second layers on the surface. Therefore, the in-gap band is considered to play crucial role for the surface superconductivity in the slightly electron-doped WO3.
Magnetic properties of Hf(P, Se)2 single crystal by high-temperature solution method using CdSe flux
Authors: Kitô H , Kawashima K , Ishida S , Fujihisa H , Gotoh Y , Iyo A , Ogino H , Eisaki H , Yoshida Y
Published: August 2022

By the high pressure and high temperature solution method mixing CdSe fluxes, layered PbFCl-type HfP2-x
Se
x
(x = 0.45) and HfSiSe single crystals were successfully grown and obtained under a high-pressure for the first time. It was clarified that the melting temperature of the solid solution was lowered by adding a small amount of CdSe. Typical sizes of ~ 180 × ~ 180 × ~ 20 μm 3 for HfP2-x
Se
x
(x = 0.45) and ~ 120 × ~ 100 × ~ 20 μm 3 for HfSiSe were obtained and characterized by scanning electron microscopy (SEM) and energy-dispersive electron spectroscopy. X-ray diffraction analysis showed that HfP2-x
Se
x
(x = 0.45) and HfSiSe were grown oriented c - axis. Magnetic susceptibility versus temperature measurement were performed for HfP2-x
Se
x
(x = 0.45). Onset of the Tc
was showed at around ~ 5.36 K for HfP2-x
Se
x
(x = 0.45) single crystal. Here, the crystal growth and magnetic properties for HfP2-x
Se
x
(x = 0.45) single crystal were presented.
The interplay between the incommensurate spin correlations and superconductivity in Mn substituted La1.90Sr0.10CuO4
Authors: Fujita Masaki , Enoki Masanori
Published: August 2022

The Mn substitution effect on superconductivity and spin correlations in La1.90Sr0.10Cu1−y
Mn
y
O4 was investigated by means of magnetic susceptibility and neutron scattering measurements. The superconducting (SC) transition temperature (T
c) and the SC volume fraction are reduced by Mn substitution with y = 0.01. It was clarified that the peak-splitting of the incommensurate (IC) low-energy spin excitations narrows by 30% and the magnetic ordering temperature is significantly enhanced in the y = 0.01 sample. Thus, the SC state and the magnetic ordering state coexist at low temperature. Furthermore, incommensurability (δ), corresponding to half the distance between the IC peaks, and T
c (∼ 18 K) of y = 0.01, both follow the linear T
c−δ relation established for the pristine La2−x
Sr
x
CuO4 (LSCO). Therefore, although Tc
varies as a result of Mn substitution, spin correlations are closely coupled to superconductivity as is the case for LSCO.
Dc vortex-flow resistivity in an epitaxially grown MgB2 film probed by pulsed current measurements
Authors: Ueno R , Ienaga K , Maegochi S , Shishido H , Okuma S
Published: August 2022

Using pulsed currents, we measure the dc vortex-flow resistivity ρf
in a fast-flow regime for an epitaxially grown MgB2 film. In the vortex-solid phase the current-voltage (I-V) characteristics in different magnetic fields B exhibit a crossover from nonlinear to linear behavior with an increase in I, indicating a change from pinning-dominated to viscous-force dominated flow. ρf
(B) extracted from the slope of the linear part of the I − V data shows an unusual field dependence with strong enhancement at low B similar to that reported from microwave surface impedance. The results suggest that two-band properties can be also detected by dc measurements with pulsed currents in MgB2 films.
Three-Dimensional Molecular Dynamics Method for Vortex pinning by Splayed Columnar Defects
Authors: Kato Masaru
Published: August 2022

We have developed three-dimensional molecular dynamics method, in which anisotropy of a superconductor and vortex core energy are included. We have applied it to a superconductor with splayed columnar defects. We have found that under a driving force due to an external current, vortices show wandering structures, which comes from the pinning force from splayed columnar defects. Especially, for weak core energy, vortices become soft or flexible. In an isotropic superconductor, these wandering structures disappear.