bluuebunny/crossref_metadata_2025 huggingface dataset:
Volatile Property of Electronic Cigarette Composition by ATR-FTIR
Authors: Gao Zhenwei , Liu Pai , Zhang Yunhong
Published: June 2023

Electronic cigarette has been said to be a less harmful substitute for traditional tobacco cigarette, customized cigarette e-liquid offers various flavors and unique experience for smokers. Different from traditional tobacco cigarette, electronic cigarette uses a heater and atomizer to heat and aerosolize the cigarette e-liquid. The study for the composition and its combustion product are flourishing thanks to the developing analysis instruments and methods. However, The volatile property, and the influence of e-cigarette smoke on environment and human health still remain unclear. In this study, we choose the RELX P53a electronic cigarette with a watermelon-flavor pod to analyse its composition by ATR-FTIR, study its volatility and discuss its influence on environment and human health. We find that propylene glycol(PG) and vegetable glycerin(VG) are the two main composition of the electronic cigarette emission, and a small amount of nicotine is added with benzoic acid to form nicotine salt, which is said to have less negative effect than pure nicotine in traditional tobacco cigarette. One of the main composition propylene glycol(PG) follows a exponential volatile process and its volatile rate falls with the increase of RH. The flow rate of air is then increased to test whether these deposited emissions could be removed. The result shows that these emissions will stay in human body and atmosphere and not easily cleared. Further studies are required to analyse the influence of small amount of compositions such as flavor essence on environment and human health and seek for reasonable regulation on the formula of electronic cigarette e-liquid.
The Application of Artificial Intelligence – Artificial Neural Networks – in Wastewater Treatment
Authors: Qiu Xinyi
Published: June 2023

Wastewater treatment is essential because it reduces the pollutant in the water, promotes the water quantity, and protects the ecosystem from harmful and toxic elements in wastewater. Many uncertainties appear in wastewater treatment systems since the natural condition is complex, and the technology of wastewater treatment is limited. Artificial Intelligence (AI) is a novel and influential technology assisting with complicated work, including modeling. The advantages of AI are evident in wastewater treatment because of the high accuracy, which leads to cost, energy, and material saving. This article mainly focuses on introducing Artificial Intelligence in wastewater treatment, displaying the application of Artificial Intelligence Neural Networks in wastewater treatment, and analyzing the advantages and problems. Overall, the research demonstrates that applying Artificial Intelligence in wastewater treatment provides a promising future with benefits, such as cost-saving and high accuracy.
Glutaraldehyde functionalized modified chitosan and grafted on PVDF membrane to achieve oil-water separation
Authors: He Qian , Ding Yuanjing , Xu Pengtao , Xu Guangying , Chen Yan
Published: June 2023

In recent years, there have been frequent offshore oil spills, and the discharge of industrial oily wastewater has not been properly solved, seriously affecting biological and water quality, and people's requirements for water quality are getting higher and higher, so it has become increasingly urgent to find green and efficient technologies and methods for separating oil-water mixtures. In this work, glutaraldehyde, a widely used crosslinker, is used to graft natural polysaccharide chitosan onto PVDF membrane, which greatly enhances the hydrophilicity of PVDF membrane, and the superhydrophilic superoleophobic CG-PVDF membrane prepared can be used to treat oily wastewater. The materials for preparing membranes are inexpensive, easy to obtain, and environmentally friendly, recyclable, and will not cause secondary pollution. Therefore, this green and simple membrane separation method for the treatment of oily wastewater is of great significance in sustainable development.
Approaches of Reutilizing Dredged Sediments from Beijing-Hangzhou Grand Canal
Authors: Wu Lijun , Yan Qiao , Luo Xiaoyong , Li Yunquan
Published: June 2023

With the implementation of the dredging project in Beijing-Hangzhou Grand Canal, proper treatment of sediment is urgent. Analysis of samples revealed a spatial difference among sampling sites, varied degree of pollutions and a strong correlation among the pollutants implying a common source of origin. Based on the sediment quantity, the contamination status quo and relevant requirements in the standards, the sediments were categorized into three types with different disposal strategy. The majority of the sediment that is not polluted or mildly contaminated were to be relocated or used as planting soil and engineering backfill geomaterial. The heavily polluted sediments were to be transported and used in a local brick manufacturing plant render it harmless.
Study on parameters limit of fracturing optimization process for thin and differential zone oil Wells
Authors: Gao Hang
Published: June 2023

The potential target of water flooding measures has gradually changed to thin differential reservoir in three types of reservoirs. The fracturing proportion of thin differential reservoir in water flooding block oil well has reached more than 60%, and the existing fracturing design code can not fully meet the needs of thin differential reservoir fracturing. Through the effect evaluation of the technical parameters matching different types of thin differential reservoir, the field test is carried out to establish the limit of the optimal technological parameters for fracturing of thin differential reservoir oil well, which is of great significance for improving the fracturing effect and improving the technical level of fracturing in the future oilfield.
Influence of groundwater level change on deep foundation pit and its control technology
Authors: Ge Xuze , Gao Yang , Jiang Yanbo , Zhao Xinyue , Wu Kun , Zhang Jie , yuan Cheng , Lin Xue , Wang Qingbiao
Published: June 2023

During the construction of deep foundation pits with rich water straight grooves, instability of deep foundation pits due to groundwater frequently occurs, posing a huge challenge to construction safety and economy. Based on the deep foundation pit of the intercity connecting line of Beijing New Airport, the technical method of combining theoretical analysis and on-site monitoring is adopted to analyze the influencing factors of groundwater on the retaining structure of deep foundation pit, and control and analyze the influencing factors. The deformation control technology for deep foundation pit is proposed. The following conclusions are obtained: (1) Based on the on-site geological conditions and the mechanism of groundwater level change, the deformation and failure forms and precipitation forms of deep foundation pits are obtained through theoretical analysis. (2) Based on the Deformation monitoring technology of deep foundation pit, the change of groundwater level and Deformation monitoring of retaining structure are carried out. (3) Combining on-site monitoring with theoretical calculation, conducting comparative analysis of data, summarizing the influencing factors of deep foundation pit damage, obtaining targeted deformation control technology for deep foundation pit, guiding the construction of practical projects, and providing reference for similar projects.
Simulation of distributed photovoltaic power generation system
Authors: Cai Gaoyuan , Li Bingbing , Liu Liqun , Zhao Zhen , Han Lulu , Lai Youfu
Published: June 2023

Combined with the operation characteristics of photovoltaic power generation system, the mathematical model and simulation model are established, and the control strategy of bipolar inverter with wide output characteristics and the maximum power point tracking (MPPT) control method of conductance increment method are designed. The maximum power output and stable operation of distributed photovoltaic power generation system are realized. The simulation results show that the photovoltaic power generation system model established in this paper can effectively reflect the characteristics of distributed photovoltaic power generation and MPPT control. With the change of lighting conditions, the distributed photovoltaic power generation system can accurately adjust the system output, which is of great significance for the research and operation of distributed photovoltaic power generation system.
Typical case analysis of oilfield tracer testing technology
Authors: Zhang Shichao
Published: June 2023

The development history and principle of interwell tracer testing and single-well tracer testing were investigated, and the application conditions and application advantages of different tracer testing were analyzed through the analysis of two types of tracer testing technologies and test results in the production process of SMi oilfield with medium porosity and low permeability, so as to provide reference for the study of tracer development in the same type of oilfield. Tracer testing technology can master the connection between injection well and production well, effectively judge the connection relationship between Wells, and provide a basis for well pattern adjustment; The seepage velocity of injected fluid in the formation can be directly observed, and the dominant injection direction can be determined, which provides reference for solving the plane contradiction. It can judge whether there is fracture system or high permeability strip, which provides ideas for high precision numerical simulation to avoid risks. It can master the remaining oil situation of single well and judge the washing efficiency of chemical agents effectively on the basis of saving investment.
Characteristics and adjustment strategies of reservoir agglomeration driving state in narrow channel sand body
Authors: Wang Jinhua
Published: June 2023

With the continuous growth of economy, we are more and more aware of the importance of energy and its preciousness. In the production of crude oil, the narrow channel is the best location for oil storage, and the underlying sand body often has oil resources. In this paper, the effect of reservoir polymer flooding is taken as the purpose, the principle of polymer flooding technology as the theoretical basis, through the analysis of dynamic change characteristics, in order to improve the adjustment parameters, to achieve reasonable and efficient exploitation of oil Wells. The application of this technology, through the development of practice, has been recognized as an effective method of oil recovery.
Productivity dynamic analysis of fractured horizontal well in ultra-low permeability reservoir
Authors: Xing YuLong
Published: June 2023

Daqing Oilfield is rich in low permeability reservoirs. In order to fully understand the development dynamics of ultra-low permeability reservoirs, this paper takes Daqing Oilfield as an example and studies the productivity dynamics of fractured horizontal Wells by numerical simulation method. The results show that the productivity of fractured horizontal Wells decreases exponentially with the decrease of formation permeability. The productivity of fractured horizontal well increases with fracture length and decreases with fracture spacing. With the increase of formation coefficient and reservoir thickness, the productivity increase of fractured horizontal Wells decreases. In the case of small well spacing, the smaller the formation coefficient and reservoir thickness, the higher the productivity of fractured horizontal Wells. Compared with conventional vertical Wells, fractured horizontal Wells have better production performance.
Research on water driving state evaluation and adjustment technology based on streamline
Authors: Hu Yue
Published: June 2023

The general reservoir engineering method is the injection volume and production between the regular injection-production well pattern (five-point method, seven-point method, nine-point method, etc.), geometric average calculation or kh method. The accuracy of the calculation results is low and it is difficult to reflect the political enemy dynamics of reservoir heterogeneity and correctly evaluate the water characteristics of reservoir development and characteristics. Problems of water injection, distribution and well efficiency are not solved. We can intuitively understand the dynamic flow characteristics of fluid in underground by using the oil-first device technology, and combined with the basic principles of reservoir engineering, a method of hydraulic reservoir dynamic evaluation is proposed. Using this method, many variables such as drainage area of oil well, flooding velocity, flooding swept area between oil Wells can be evaluated quantitatively, and the development effect of oil field can be evaluated accurately. According to the analysis of the characteristics and factors of the distribution of the wire, the corresponding adjustment measures are taken to make the dominant wire weaker and the weak wire stronger, and finally achieve the purpose of improving the recovery rate.
Spatio-temporal heterogeneity of transportation carbon emissions and its driving factors in China’s main urban agglomerations
Authors: Wei Shicheng
Published: June 2023

The transportation sector in China has the characteristics of large total carbon emissions, high level, and unbalanced spatial distribution. For carbon emissions reduction, it is of great significance to study the carbon emissions of transportation in China in different regions. Focusing on China’s three urban agglomerations: Beijing-Tianjin-Hebei Region, Yangtze River Delta Region and Pearl River Delta Region, this paper explores and compares the spatio-temporal heterogeneity of China’s traffic carbon emissions from 2000 to 2019 by using methods such as GWR and ESDA. The results show that: 1) As for carbon emissions, the total carbon emissions and per capita carbon emissions of the three urban agglomerations have shown a significant growth trend. The high-value aggregation in Beijing-Tianjin-Hebei Region has weakened, the high-value and low-value aggregation in the Yangtze River Delta Region has increased, and the change in the Pearl River Delta Region is not obvious. 2) As for influencing factors, motor vehicle ownership has the greatest impact on regional carbon emissions, but the impact intensity of motor vehicle ownership on carbon emissions of the three urban agglomerations is different. 3) As for spatio-temporal heterogeneity, after 2010, the spatial correlation of carbon emissions of the three urban agglomerations was lower than that of the surrounding areas, and all of them were weakened.
Comparative Study of Sub-23nm Particle Number Emission Characteristics for Non-road Diesel Engine on RMC and NRSC Test
Authors: Huo Yongzhan , Wang Xiaowei , Gao Tao , Liu Kang , Wang Zhenyu
Published: June 2023

A non-road diesel engine meeting China IV emission regulation was selected, the RMC and NRSC test procedures of the EU non-road Stage V emission regulation were run on the engine test bench. The emissions of particle number (PN) with particle sizes above 23 nm and 10 nm were tested simultaneously using direct exhaust sampling and full-flow dilution channel CVS dilution sampling equipment. The results showed that the emission characteristics of particulate matter above 23 nm and above 10 nm in the RMC test had the same trend, and the cumulative PN emissions were 1.9×1012 and 2.3×1012 for the whole test cycle, respectively. The PN23 values of dilution sampling were higher than those of direct sampling. The main reason for the difference in PN emission values at the same working modes in RMC and NRSC is the change in DPF capture efficiency caused by the different order of working modes and conditions.
Photonics in Finland
Authors: Purmonen Juha , Pakarinen Tuukka , Vellamo Tea
Published: June 2023

Finland has a long tradition of photonics research and industry, which has led to many pioneer photonics related technologies developed in the country. Together with a worldclass research and education environment, wide range of competencies and leading knowhow in optical sensing and imaging, microand nanophotonics, lasers and fiber optics, and in extended reality (XR), makes Finland an ideal place for innovations in photonics, commercialization of new products, company growth, and for international success.
Twisted photons: what is the orbital angular momentum of light?
Authors: Cardano Filippo , Marrucci Lorenzo
Published: June 2023

In this introductory article, we explain the concept of orbital angular momentum (OAM) of light, discussing its physical meaning and its relationship with the more familiar spin angular momentum of circularly polarized waves. We address both classical and quantum aspects, emphasizing the distinction between OAM eigenstates – helical waves – and the general case. Finally, we briefly touch upon the main optical techniques to generate these optical states and emerging applications in the field.
Exposure dose estimation considering a molybdenum generator fall accident
Authors: Sagisaka Y. , Tsujiguchi T. , Narumi K. , Shikata I. , Shirakawa K. , Hosokawa S. , Ito K. , Takahashi Y.
Published: June 2023

Radiopharmaceuticals with high radioactivity are used in the field of nuclear medicine. Moreover, understanding the exposure dose of radiation workers and the air dose in radioisotope preparation rooms is essential. In particular, evaluating exposure dose assuming an accident to reduce radiation exposure as much as possible and respond to the accident is paramount. Thus, we evaluated a case study where 1.34 GBq 99Mo–99mTc generator used in our hospital fell, and evaluated exposure doses. The results of the considered drop accident of a commercially available generator indicated a possibility of radiation exposure equivalent to several months of normal work exposure, even though the possibility of radiation exposure to the extent that deterministic biological effects appear is low. Therefore, more attention must be paid to managing radiopharmaceuticals with high radioactivity, such as generators, to reduce the anxiety of radiation workers in the hospital and respond rapidly to accidents. Furthermore, the study findings should be used for staff training during normal times to avoid unnecessary radiation exposure.
Degree conditions for path-factor critical deleted or covered graphs
Authors: Liu Hongxia
Published: June 2023

A path-factor of a graph G is a spanning subgraph of G whose components are paths. A P≥d-factor of a graph G is a path-factor of G whose components are paths with at least d vertices, where d is an integer with d ≥ 2. A graph G is P≥d-factor covered if for any e ∈ E(G), G admits a P≥d-factor including e. A graph G is (P≥d, n)-factor critical deleted if for any Q ⊆ V(G) with |Q| = n and any e ∈ E(G − Q), G – Q − e has a P≥d-factor. A graph G is (P≥d, n)-factor critical covered if for any Q ⊆ V(G) with |Q| = n, G − Q is a P≥d-factor covered graph. In this paper, we verify that (1) an (n + t + 2)-connected graph G of order p with p ≥ 4t + n + 7 is (P≥3, n)-factor critical deleted if max $ \left\{{d}_G({v}_1),{d}_G({v}_2),\dots,{d}_G({v}_{2t+1})\right\}\ge \frac{p+2n}{3}$ for any independent set {v1, v2, …, v2t+1} of G, where n and t are two nonnegative integers with t ≥ 1; (2) an (n + t + 1)-connected graph G of order p with p ≥ 4t + n + 5 is (P≥3, n)-factor critical covered if max $ \left\{{d}_G({v}_1),{d}_G({v}_2),\dots,{d}_G({v}_{2t+1})\right\}\ge \frac{p+2n+2}{3}$ for any independent set {v1, v2, …, v2t+1} of G, where n and t are two nonnegative integers with t ≥ 1.
MRT mit Herzschrittmacher – eine interdisziplinäre
Herausforderung
Authors: Gerth Sophia
Published: June 2023

Wir erleben es immer häufiger, dass Patienten ein MRT benötigen,
die einen Herzschrittmacher oder einen implantierten Kardioverter-Defibrillator
haben. Doch wie geht man mit diesen Patienten um und wie kann man diese
Patienten sicher untersuchen? Dieser Beitrag soll zeigen, wie entsprechende
Patienten sicher und in Zusammenarbeit verschiedener Fachrichtungen untersucht
werden können.
Myokardiale Perfusion und Vitalität mittels
MRT
Authors: Schuck Linus , Beitzke Dietrich
Published: June 2023

Among other imaging modalities, cardiac MRI is an established modality for the
detection of myocardial ischemia and viability. With updated guidelines, the
demand for this modality will increase in the coming years. The aim of
noninvasive functional testing is to prove or rule out myocardial ischemia and
viability using stress perfusion and late gadolinium enhancement.
Qualitätsprüfung von Strahlenschutzkleidung: ein
Vergleich von Prüfverfahren
Authors: Staud Fabian
Published: June 2023

Dieser Artikel zeigt eine Übersicht der vorgegebenen
Prüfmodalitäten nach DIN 6857–2 (04/2021) zur
Qualitätsprüfung von Röntgenschutzkleidung. Es werden
die jeweiligen Methoden diskutiert. Die gewählten Prüfverfahren
werden hinsichtlich der Kriterien Aufwand, Dauer sowie Zuverlässigkeit
anhand eines festgelegtern Kollektivs verschiedener Strahlenschutzkleidung
analysiert und beurteilt.
Empfehlungen der Deutschen Gesellschaft für HNO-Heilkunde, Kopf- und Hals-Chirurgie (DGHNO-KHC) für die Erteilung der fachspezifischen Weiterbildungsbefugnis
Authors: Guntinas-Lichius Orlando , Lang Stephan , Stöver Timo , Hoffmann Thomas K. , Plontke Stefan , Welkoborsky Hans-Jürgen , Zahnert Thomas , Lippert Burkard M. , Rotter Nicole , Dazert S. , Dietz Andreas , Deitmer Thomas
Published: June 2023

Die Musterweiterbildungsordnung 2018 der Bundesärztekammer für die Facharztweiterbildung „Hals-Nasen-Ohrenheilkunde“ wird zunehmend durch die Landesärztekammern in Kraft gesetzt. Ein hierzu passender, fachlich empfohlener Weiterbildungsplan (FEWP) wurde von der Deutschen Gesellschaft für Hals-Nasen-Ohren-Heilkunde, Kopf- und Hals-Chirurgie (DGHNO-KHC) gemeinsam mit dem Berufsverband Deutscher HNO-Ärzte konsentiert und als Muster für die Landesärztekammern empfohlen.

In diesem Kontext werden von den Landesärztekammern Kriterien erarbeitet, anhand derer Befugnisse für eine Weiterbildung zuerkannt werden können.

Die DGHNO-KHC hat letztmalig 1999 Empfehlungen für die Erteilung von Weiterbildungsbefugnissen für die Weiterbildung HNO-Heilkunde gegeben. Durch die Musterweiterbildungsordnung 2018 haben sich viele Inhalte geändert. Daher soll hiermit den Landesärztekammern ein fachlich-wissenschaftlich formulierter Vorschlag für die Zuerkennung von Weiterbildungsbefugnissen an die Hand gegeben werden.
Typische Probleme und Fehler im radiologischen
Nachtdienst
Authors: Storjohann Svea , Pusch Anika , Kessler Rebecca , Kirsch Michael
Published: June 2023

Außerhalb der Regelarbeitszeit wird der Präsenzdienst in den
meisten Krankenhäusern von Weiterbildungsassistenten geleistet. Sie sind
gut beraten, einerseits die wichtigsten Krankheitsbilder zu kennen, die in
dieser Übersichtsarbeit dargestellt werden, und andererseits die
Fälle, die sie nicht lösen können, an ihren Hintergrund
weiterzuleiten.
Mast Cell and Innate Immune Cell Communication in Cholestatic Liver Disease
Authors: Bernard Jessica K. , Marakovits Corinn , Smith Leah G. , Francis Heather
Published: June 2023

Mast cells (MCs) contribute to the pathogenesis of cholestatic liver diseases (primary sclerosing cholangitis [PSC] and primary biliary cholangitis [PBC]). PSC and PBC are immune-mediated, chronic inflammatory diseases, characterized by bile duct inflammation and stricturing, advancing to hepatobiliary cirrhosis. MCs are tissue resident immune cells that may promote hepatic injury, inflammation, and fibrosis formation by either direct or indirect interactions with other innate immune cells (neutrophils, macrophages/Kupffer cells, dendritic cells, natural killer, and innate lymphoid cells). The activation of these innate immune cells, usually through the degranulation of MCs, promotes antigen uptake and presentation to adaptive immune cells, exacerbating liver injury. In conclusion, dysregulation of MC-innate immune cell communications during liver injury and inflammation can lead to chronic liver injury and cancer.
Performance of endoscopic submucosal dissection for undifferentiated early gastric cancer: a multicenter retrospective cohort
Authors: Papaefthymiou Apostolis , Kahaleh Michel , Lemmers Arnaud , Sferrazza Sandro , Barret Maximilien , Yamamoto Katsumi , Deprez Pierre , Marín-Gabriel José C. , Tribonias George , Ouyang Hong , Barbaro Federico , Kiosov Oleksandr , Seewald Stefan , Patil Gaurav , Elkholy Shaimaa , Coumaros Dimitri , Vuckovic Clemence , Banks Matthew , Haidry Rehan , Mavrogenis Georgios
Published: June 2023

Background and study aims Undifferentiated early gastric cancer (UD-EGC) represents an extended indication for endoscopic submucosal dissection (ESD) based on the existing guidelines. This study evaluated the prevalence of UD-EGC recurrence after ESD, and potentially implicated risk factors.

Patients and methods Data from 17 centers were collected retrospectively including demographics, endoscopic and pathological findings, and follow-up data from UD-EGC cases treated by ESD. Patients with incomplete resection or advanced disease were excluded. Descriptive statistics quantified variables and calculated the incidence of recurrence. Chi-square test was applied to assess any link between independent variables and relapse; significantly associated variables were inserted to a multivariable regression model.

Results Seventy-one patients were eligible, with 2:1 female to male ratio and age of 65.8 ± 11.8 years. Mean lesion size was 33.5 ± 18.8 mm and the most frequent histological subtype was signet ring-cells UGC (2:1). Patients were followed-up every 5.6 ± 3.7 months with a mean surveillance period of 29.3 ± 15.3 months until data collection. Four patients (5.6%) developed local recurrence 8.8 ± 6.5 months post-ESD, with no lymph node or distal metastases been reported. Lesion size was not associated with recurrence (P = 0.32), in contrast to lymphovascular and perineural invasion which were independently associated with local recurrence (P = 0.006 and P < 0.001, respectively).

Conclusions ESD could be considered as the initial step to manage UD-EGC, providing at least an “entire-lesion” biopsy to guide therapeutic strategy. When histology confirms absence of lymphovascular and perineural invasion, this modality could be therapeutic, providing low recurrence rates.
Relating the artificial chemotaxis of catalysts to a gradient descent of the free energy
Authors: Krist Kathleen T. , Noid W. G.
Published: June 2023

Recent experiments suggest that mesoscale catalysts are active materials that power their motion with chemical free energy from their environment and also “chemotax” with respect to substrate gradients. In the present work, we explore a thermodynamic framework for relating this chemotaxis to the evolution of a system down the gradient of its free energy. This framework builds upon recent studies that have employed the Wasserstein metric to describe diffusive processes within the Onsager formalism for irreversible thermodynamics. In this work, we modify the Onsager dissipation potential to explicitly couple the reactive flux to the diffusive flux of catalysts. The corresponding gradient flow is a modified reaction-diffusion equation with an advective term that propels the chemotaxis of catalysts with the free energy released by chemical reactions. In order to gain first insights into this framework, we numerically simulate a simplified model for spherical catalysts undergoing artificial chemotaxis in one dimension. These simulations investigate the thermodynamic forces and fluxes that drive this chemotaxis, as well as the resulting dissipation of free energy. Additionally, they demonstrate that chemotaxis can delay the relaxation to equilibrium and, equivalently, prolong the duration of nonequilibrium conditions. Although future simulations should consider a more realistic coupling between reactive and diffusive fluxes, this work may provide insight into the thermodynamics of artificial chemotaxis. More generally, we hope that this work may bring attention to the importance of the Wasserstein metric for relating nonequilibrium relaxation to the thermodynamic free energy and to large deviation principles.
Influences of spatial structure of plasma shock wave on electromagnetic wave propagation characteristics
Authors: Liang Hao , Li Jiangting , Guo Lixin , Guo Linjing , Liu Wei , Liu Zhongyu
Published: June 2023

Plasma shock waves represent high-speed, nonlinear motion states of plasma in which the physical parameters of fluid, such as density, temperature, and velocity, vary dramatically within a limited space. These variations make studying electromagnetic wave propagation in plasma shock waves difficult. In this study, we calculate the spatial distribution of the plasma frequency and collision frequency in the plasma shock layer based on the one-dimensional structure of the plasma shock wave. In the process from upstream to downstream of the plasma shock wave, the plasma frequency increases as a function of electron density; downstream, the plasma frequency increases as a function of the free stream Mach number, while the collision frequency decreases first and then increases. We also use the recursive convolution finite-difference time-domain method to calculate the propagation of the electromagnetic wave in the plasma shock layer. The absorption of the plasma shock layer to the electromagnetic wave decreases gradually as a function of the electromagnetic wave frequency. The absorption of the plasma shock layer downstream of the electromagnetic wave is greater than that upstream owing to the larger plasma frequency. In the case of low-Mach numbers, the wavelength of the electromagnetic wave downstream is larger than that upstream. In the case of high-Mach numbers, the thickness of the entire shock layer is much greater than that at low-Mach numbers. Due to the nonlinear effects of electromagnetic processes in plasmas, a modulation phenomenon occurs when electromagnetic waves propagate in the shock layer. In the case of low frequencies, the electromagnetic wave gave rise to a modulation phenomenon that resembled the beat phenomenon. When the electromagnetic wave frequency increased, a modulation phenomenon gradually appeared that resembled the oscillation superimposed on a sine wave. Further increases in the electromagnetic wave frequency led to the gradual disappearance of the modulation phenomenon.
The effect of the shroud window membrane on the x-ray drive characterization of cryogenic hohlraums
Authors: Yang Dong , Li Zhichao , Li Sanwei , Hou Lifei , Guo Liang , Zhu Tuo , Yi Rongqing , Du Huabing , Song Tianming , Jiang Xiaohua , Peng Xiaoshi , Zhan Xiayu , Li Yulong , Wang Feng , Yang Jiamin , Jiang Shaoen , Zheng Jian , Ding Yongkun
Published: June 2023

Both direct and indirect drive concepts of inertial confinement fusion rely on targets with cryogenic thermonuclear fuel shells for ignition. Experiments on the Shenguang-III prototype laser facility using laser-driven gas-filled hohlraums show distinct differences between cryogenic (20 K) and warm hohlraums. Although the measured x-ray flux in the photon range from 1.6 to 4.4 keV (Au M-band) is identical between cryogenic and warm hohlraums, the cryogenic hohlraum has a much slower rate of rise and is 20% lower in peak intensity of x-ray flux in the photon range from 0.1 to 4 keV. The reasons for this drive deficit between cryogenic and warm hohlraums are investigated using a similar series of hohlraum experiments. The experiments employ three types of hohlraums to distinguish the effect of a shroud window membrane and condensates. Warm hohlraums with a shroud window membrane replicate the slower rate of rise of radiation flux of cryogenic targets. When the shroud window is present, the measured x-ray flux in the hohlraum shows a drive deficit that decreases with time. However, the measured deficit increases as the viewing angle increases. All of these results indicate that the portion of the shroud not illuminated by the lasers absorbs the outgoing x-ray flux from the hohlraum.
Polarized tip-enhanced Raman spectroscopy at liquid He temperature in ultrahigh vacuum using an off-axis parabolic mirror
Authors: Peis L. , He G. , Jost D. , Rager G. , Hackl R.
Published: June 2023

Tip-enhanced Raman spectroscopy (TERS) combines inelastic light scattering well below the diffraction limit down to the nanometer range and scanning probe microscopy and, possibly, spectroscopy. In this way, topographic and spectroscopic as well as single- and two-particle information may simultaneously be collected. While single molecules can now be studied successfully, bulk solids are still not meaningfully accessible. It is the purpose of the work presented here to outline approaches toward this objective. We describe a home-built, liquid helium cooled, ultrahigh vacuum TERS. The setup is based on a scanning tunneling microscope and, as an innovation, an off-axis parabolic mirror having a high numerical aperture of ∼0.85 and a large working distance. The system is equipped with a fast load-lock chamber, a chamber for the in situ preparation of tips, substrates, and samples, and a TERS chamber. Base pressure and temperature in the TERS chamber were ∼3 × 10−11 mbar and 15 K, respectively. Polarization dependent tip-enhanced Raman spectra of the vibration modes of carbon nanotubes were successfully acquired at cryogenic temperature. The new features described here including very low pressure and temperature and the external access to the light polarizations, thus the selection rules, may pave the way toward the investigation of bulk and surface materials.
Simultaneous determination of electrical conductivity and thickness of nonmagnetic metallic foils using two-sided multifrequency eddy current techniques
Authors: White A. D. , Drouillard T. A. , Ludwig S. , Ferriera A. J. , Heinz K. G. , Young A. J.
Published: June 2023

In this paper, we describe a simple method for performing multifrequency eddy current characterization of free-standing uniform-thickness metallic foils using a forked inductive coil arrangement. The method involves measuring the mutual inductance between two coils when a foil is present between the coils, and when it is not present; the ratio of these mutual inductances is compared with an analytical solution, and foil conductivity, thickness, and sheet resistance are simultaneously estimated using numerical inversion and least-squares fitting. This method was used to characterize 34 non-ferrous metallic samples with thicknesses between 50 and 640 μm and with conductivities between 0.8 × 107 and 5.8 × 107 S/m. The estimated thicknesses from eddy current characterization agreed well with those measured using confocal optical techniques; the two approaches agreed to within 1 μm for samples that were thinner than 200 μm, and to within 0.5% for samples that had a thickness of 200 μm or greater. The estimated conductivities from eddy current characterization were in close agreement with expected values, given knowledge of the materials used. A particular strength of this approach is that the instrumentation needed is broadly available in research and development laboratories and the associated fixturing is easy to manufacture and assemble. A calibration procedure is described that can be used to reduce errors from geometric uncertainties. This calibration requires a sample that has only a known conductivity or thickness; both do not need to be known. The method described herein is likely extensible to conductivities and thickness well outside the ranges measured as part of this work.
AlN/AlGaN/AlN quantum well channel HEMTs
Authors: Singhal Jashan , Kim Eungkyun , Hickman Austin , Chaudhuri Reet , Cho Yongjin , Xing Huili Grace , Jena Debdeep
Published: June 2023

We present a compositional dependence study of electrical characteristics of AlxGa1−xN quantum well channel-based AlN/AlGaN/AlN high electron mobility transistors (HEMTs) with x=0.25,0.44, and 0.58. This ultra-wide bandgap heterostructure is a candidate for next-generation radio frequency and power electronics. The use of selectively regrown n-type GaN Ohmic contacts results in contact resistance that increases as the Al content of the channel increases. The DC HEMT device characteristics reveal that the maximum drain current densities progressively reduce from 280 to 30 to 1.7 mA/mm for x=0.25,0.44, and 0.58, respectively. This is accompanied by a simultaneous decrease (in magnitude) in threshold voltage from −5.2 to −4.9 to −2.4 V for the three HEMTs. This systematic experimental study of the effects of Al composition x on the transistor characteristics provides valuable insights for engineering AlGaN channel HEMTs on AlN for extreme electronics at high voltages and high temperatures.
Required toroidal confinement for fusion and omnigeneity
Authors: Boozer Allen H.
Published: June 2023

Deuterium–tritium (DT) burning requires a long energy confinement times compared to collision times, so the particle distribution functions must approximate local Maxwellians. Non-equilibrium thermodynamics is applicable, which gives relations among transport, entropy production, the collision frequency, and the deviation from a Maxwellian. The distribution functions are given by the Fokker–Planck equation, which is an advection–diffusion equation. A large hyperbolic operator, the Vlasov operator with the particle trajectories as its characteristics, equals a small diffusive operator, the collision operator. The collisionless particle trajectories would be chaotic in stellarators without careful optimization. This would lead to rapid entropy production and transport—far beyond what is consistent with a self-sustaining DT burn. Omnigeneity is the weakest general condition that is consistent with a sufficiently small entropy production associated with the thermal particle trajectories. Omnigeneity requires that the contours of constant magnetic field strength be unbounded in at least one of the two angular coordinates in magnetic surfaces and that there be a symmetry in the field-strength wells along the field lines. Even in omnigenous plasmas, fluctuations due to microturbulence can produce chaotic particle trajectories and the gyro-Bohm transport is seen in many stellarator and tokamak experiments. The higher the plasma temperature above 10 keV, the smaller the transport must be compared to gyro-Bohm for a self-sustaining DT burn. The hot alphas of DT fusion heat the electrons. When the ion–electron equilibration time is long compared to the ion energy confinement time, a self-sustaining DT burn is not possible, which sets a limit on the electron temperature.
Compact sample environment for in situ X-ray scattering during spin-coating
Authors: Kneschaurek Ekaterina , Hinderhofer Alexander , Hofferberth Bernd , Scheffczyk Niels , Pithan Linus , Zimmermann Paul , Merten Lena , Bertram Florian , Schreiber Frank
Published: June 2023

We demonstrate a compact sample environment for the in situ study of crystallization kinetics of thin films on synchrotron beamlines, featuring atmospheric control, automated deposition, spin-coating, and annealing stages. The setup is suitable for studying thin film growth in real time using grazing-incidence X-ray diffraction techniques. Humidity and oxygen levels are being detected by sensors. The spinning stage exhibits low vertical oscillation amplitude (∼3μm at speeds up to 10 000 rpm) and can optionally be employed for antisolvent application or gas quenching to investigate the impact of these techniques, which are often used to assist thin film growth. Differential reflectance spectroscopy is implemented in the spin-coater environment for inspecting thin film thickness and optical properties. The infrared radiation-based annealing system consists of a halogen lamp and a holder with an adjustable lamp-to-sample distance, while the sample surface temperature is monitored by a pyrometer. All features of the sample environment can be controlled remotely by the control software at synchrotron beamlines. In order to test and demonstrate the performance, the crystallization pathway of the antisolvent-assisted MAPbI3 (MA = methylammonium) perovskite thin film during the spinning and annealing stages is monitored and discussed.
Electronic specific heat capacities and entropies from density matrix quantum Monte Carlo using Gaussian process regression to find gradients of noisy data
Authors: Van Benschoten William Z. , Weiler Laura , Smith Gabriel J. , Man Songhang , DeMello Taylor , Shepherd James J.
Published: June 2023

We present a machine learning approach to calculating electronic specific heat capacities for a variety of benchmark molecular systems. Our models are based on data from density matrix quantum Monte Carlo, which is a stochastic method that can calculate the electronic energy at finite temperature. As these energies typically have noise, numerical derivatives of the energy can be challenging to find reliably. In order to circumvent this problem, we use Gaussian process regression to model the energy and use analytical derivatives to produce the specific heat capacity. From there, we also calculate the entropy by numerical integration. We compare our results to cubic splines and finite differences in a variety of molecules in which Hamiltonians can be diagonalized exactly with full configuration interaction. We finally apply this method to look at larger molecules where exact diagonalization is not possible and make comparisons with more approximate ways to calculate the specific heat capacity and entropy.
Effects of side-wall air cooling on solar thermoelectric generation with high aspect-ratio, V-shaped P/N couples
Authors: Li Xinjie , Mohankumar Thiraj , Bahk Je-Hyeong
Published: June 2023

Solar thermoelectric generators (STEGs) often require long thermoelectric (TE) legs and efficient cooling at the cold side to increase the temperature difference across TE legs and, thus, the power output. We investigate the effects of direct side-wall air cooling of TE legs on the power output of STEGs fabricated with high aspect-ratio as well as V-shaped p-type and n-type TE couples without additional heat sinks. Wire-type metallic TE materials are welded together to create V-shape TE leg arrays without additional electrodes and attached to a ceramic plate with a solar absorber on top to complete the STEG. The power generation performance of the STEG is investigated with varying wind speed under concentrated solar irradiation. Finite element simulation is performed to further analyze the heat transfer and thermoelectric performance. We find that although sidewall air cooling helps to keep the cold-side temperature cooler in both natural and forced convection regimes, it can also lower the hot-side temperature to reduce the net temperature difference and, thus, the power output and efficiency. Partial thermal insulation of TE couples can further enhance the power output under forced air convection by keeping the hot side temperature higher. The developed STEG achieves a maximum power density of 230 μW/cm2 and a system efficiency of 0.023% under 10 suns with natural convection. The low efficiency was mainly due to the low ZT of the metallic TE materials used and the unoptimized leg length. Our simulation shows that the system efficiency can be improved to 2.8% with state-of-the-art Bi2Te3 alloys at an optimal leg length.
Evolution of colloidal coatings due to a wetting and drying process
Authors: Pauchard Ludovic
Published: June 2023

Paints and coatings are usually made by depositing a volatile liquid containing dispersed colloidal particles. The dry film is obtained through the evaporation of the volatile liquid. Depending on the ability of the particles to deform under capillary effect, we show that the drying can yield continuous coatings with no porosity, uniform porous coatings, or the formation of singularities, such as cracks causing the final film to be non-uniform. The evolution of the resulting coatings is then subjected to a wetting and drying process. Wetting leads to an increase in the water content of the unsaturated porous coating while drying results in water reduction. The response of the coatings to such a process can exhibit slight or significant changes in the morphology of the coatings that are related to their rheological properties. In particular, the growth of blisters is reported during the wetting and drying process.
Twinning in cattle: a pathway for reducing the methane intensity of beef
Authors: Gebbels J. N. , Kragt M. E. , Vercoe P. E.
Published: June 2023

Context Reducing livestock emissions, the largest single contributor to agricultural emissions, is increasingly recognised as a high priority. The low biological efficiency of beef cattle, due to their long gestation period, long generational interval, and propensity to be uniparous, contributes to the high methane emissions intensity (kg CO2-e/kg product) of beef compared to most other food products. Aims We evaluate the potential of increasing the frequency of multiparous births (twinning) as a pathway to reducing the methane intensity of beef and the net methane emissions of intensive beef systems. Methods We simulate a uniparous herd structure and emissions profile using GrassGro™ livestock systems modelling software and then calculate the effects of an increasing frequency of multiparous births (twinning), up to 1.53 calves per cow joined, on methane emissions. Key results Our results demonstrate that beef from calves reared as twins has a 22% lower methane intensity than beef from a single reared calf. Although twinning reduces the methane intensity of beef, at the herd level, net methane emissions could rise by as much as 23% at 1.53 calves per cow joined if overall herd size is allowed to grow through an increased number of calves. If we decrease stocking rates, whilst also increasing twinning rates, it is possible to reduce net emissions by up to 14%, without changing productivity. Conclusions Our results illustrate the significant potential of twinning to decrease the methane intensity of beef and to increase the productivity per cow in intensive beef systems. Implications Despite this, twinning is unlikely to be a viable net emissions reduction pathway – as twinning will increase stocking rate unless herd structure is altered – unless a commercial or policy driver to reduce net methane emissions is established.
Exploring the impact of airtanker drops on in-stand temperature and relative humidity
Authors: Wheatley Melanie , Cotton-Gagnon Anne , Boucher Jonathan , Wotton B. Mike , McFayden Colin B. , Jurko Natasha , Robinson Jason
Published: June 2023

Background There has been little quantification of the extent and duration of micrometeorological changes within a forest after airtanker drops of water-based suppressant. It has been speculated that a period of prolonged relative humidity – referred to as a ‘relative humidity (RH) bubble’ – temporarily exists in the canopy understorey post-drop. Aims We quantify the RH bubble from the drops of five airtankers commonly used by wildland fire management organisations in Canada. Methods We measured airtankers dropping water, foam concentrates, and gel enhancers in a mature jack pine stand. We examined the duration of change in RH and temperature using Generalised Additive Models, and the consequence of these changes on fine fuel moisture. Key results The average maximum RH increased and temperature decreased, indicating that the effects of the ‘RH bubble’ in-stand lasted from 25 to 76 min, depending upon the airtanker type and load configuration. Conclusion Airtanker drops cause an in-stand increase in RH and decrease in temperature, but this ambient change has a limited effect on potential fire behaviour. Implications The direct effect of water wetting the fuel is the most impactful effect of an airtanker drop. The ‘RH bubble’ created, though observable, does not change fine fuel moisture enough to impact fire behaviour.