Pub Date : 2024-09-03DOI: 10.1088/1361-6463/ad6fb2
Engin Aşlar
This study aims to investigate both light-induced fading effects on thermoluminescence (TL) and optically stimulated luminescence (OSL) signals under three different light sources (fluorescent, UV-254 and daylight) and dose reassessment with phototransferred TL (PTTL) signals in Beryllium oxide dosimeters. TL and OSL signals were deconvoluted for each light source. Accordingly, variations in the maximum peak temperature, activation energy, peak area value for the TL signal, and intensity and lifetime values for the OSL signal were monitored. Each peak, OSL component, and total area value exhibited different behaviors depending on the light source. Considering the total area condition, the TL intensity decreased by ∼90%, ∼80%, and ∼70% in UV-254, daylight, and fluorescent light exposure, respectively, at the end of the 120 min. On the other hand, the OSL total area intensity faded quickly for both UV-254 and daylight, while it decreased by ∼45% for fluorescent light. According to these results, regardless of TL and OSL measurements, the dosimeters should be kept primarily away from daylight and fluorescent light after irradiation, instead of UV-254, which is rarely encountered in daily life. The feasibility of dose reassessment using PTTL signals under UV-254 light was investigated within a wide dose range from 0.1 to 128 Gy. It is feasible to reassess doses between 0.5 and 32 Gy considering the total area intensity of PTTL signals. In conclusion, PTTL signals can be easily used in fields of the order of Gy, such as in reevaluating doses in radiotherapy applications.
{"title":"Light-induced fading effects on TL and OSL signals and feasibility of dose re-assessment with PTTL signals in BeO dosimeters","authors":"Engin Aşlar","doi":"10.1088/1361-6463/ad6fb2","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6fb2","url":null,"abstract":"This study aims to investigate both light-induced fading effects on thermoluminescence (TL) and optically stimulated luminescence (OSL) signals under three different light sources (fluorescent, UV-254 and daylight) and dose reassessment with phototransferred TL (PTTL) signals in Beryllium oxide dosimeters. TL and OSL signals were deconvoluted for each light source. Accordingly, variations in the maximum peak temperature, activation energy, peak area value for the TL signal, and intensity and lifetime values for the OSL signal were monitored. Each peak, OSL component, and total area value exhibited different behaviors depending on the light source. Considering the total area condition, the TL intensity decreased by ∼90%, ∼80%, and ∼70% in UV-254, daylight, and fluorescent light exposure, respectively, at the end of the 120 min. On the other hand, the OSL total area intensity faded quickly for both UV-254 and daylight, while it decreased by ∼45% for fluorescent light. According to these results, regardless of TL and OSL measurements, the dosimeters should be kept primarily away from daylight and fluorescent light after irradiation, instead of UV-254, which is rarely encountered in daily life. The feasibility of dose reassessment using PTTL signals under UV-254 light was investigated within a wide dose range from 0.1 to 128 Gy. It is feasible to reassess doses between 0.5 and 32 Gy considering the total area intensity of PTTL signals. In conclusion, PTTL signals can be easily used in fields of the order of Gy, such as in reevaluating doses in radiotherapy applications.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"40 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-02DOI: 10.1088/1361-6463/ad726e
K N Kornev, A A Logunov, S A Dvinin
A low-current gliding discharge (current range 1–5 A) in high-speed air flows of 100–250 m s−1 was experimentally studied. A high-voltage direct current source with a maximum voltage of 4.5 kV was used to create the discharge. The average electron concentration ne ∼ 1014 cm−3 and the plasma ionization degree were determined by measuring the Stark broadening of the hydrogen Hβ line (λHβ = 486.1 nm). The estimates of the electric field (E ∼ 100 V cm −1 ÷ 600 V cm−1) in the discharge positive column were found using time-synchronized high-speed video recordings and oscillograms. The gas rotational temperature Tg = 7000–9500 K and the vibrational temperature Tv = 7000–11 000 K were estimated using optical emission spectroscopy. Time-resolved spectroscopy is used to investigate the effective plasma channel spatial regions from which the N, NH, N2+, O and OH molecules radiate. The difference of the obtained radii indicates the presence of a radial temperature gradient and inhomogeneous plasma composition in the discharge cross section. The possibility of using of gliding discharge to ignite hydrocarbon-air mixtures in the ramjet engines combustors has been experimentally demonstrated.
实验研究了 100-250 m s-1 高速气流中的低电流滑行放电（电流范围 1-5 A）。产生放电的是一个最大电压为 4.5 kV 的高压直流电源。通过测量氢 Hβ 线的斯塔克展宽（λHβ = 486.1 nm），确定了平均电子浓度 ne ∼ 1014 cm-3 和等离子体电离度。放电正柱中的电场（E ∼ 100 V cm -1 ÷ 600 V cm-1）是通过时间同步的高速视频记录和振荡图估算出来的。气体旋转温度 Tg = 7000-9500 K 和振动温度 Tv = 7000-11000 K 是通过光学发射光谱估算的。时间分辨光谱法用于研究 N、NH、N2+、O 和 OH 分子辐射的有效等离子体通道空间区域。获得的半径差异表明放电截面存在径向温度梯度和不均匀等离子体成分。实验证明了在冲压式喷气发动机燃烧器中使用滑行放电点燃碳氢化合物-空气混合物的可能性。
{"title":"Low-current gliding DC discharge in high-speed flows","authors":"K N Kornev, A A Logunov, S A Dvinin","doi":"10.1088/1361-6463/ad726e","DOIUrl":"https://doi.org/10.1088/1361-6463/ad726e","url":null,"abstract":"A low-current gliding discharge (current range 1–5 A) in high-speed air flows of 100–250 m s<sup>−1</sup> was experimentally studied. A high-voltage direct current source with a maximum voltage of 4.5 kV was used to create the discharge. The average electron concentration <italic toggle=\"yes\">n</italic><sub>e</sub> ∼ 10<sup>14</sup> cm<sup>−3</sup> and the plasma ionization degree were determined by measuring the Stark broadening of the hydrogen H<italic toggle=\"yes\"><sub>β</sub></italic> line (<italic toggle=\"yes\">λ</italic><sub>H<italic toggle=\"yes\">β</italic></sub> = 486.1 nm). The estimates of the electric field (<italic toggle=\"yes\">E</italic> ∼ 100 V cm <sup>−1</sup> ÷ 600 V cm<sup>−1</sup>) in the discharge positive column were found using time-synchronized high-speed video recordings and oscillograms. The gas rotational temperature <italic toggle=\"yes\">T</italic><sub>g</sub> = 7000–9500 K and the vibrational temperature <italic toggle=\"yes\">T</italic><sub>v</sub> = 7000–11 000 K were estimated using optical emission spectroscopy. Time-resolved spectroscopy is used to investigate the effective plasma channel spatial regions from which the N, NH, N<sub>2</sub><sup>+</sup>, O and OH molecules radiate. The difference of the obtained radii indicates the presence of a radial temperature gradient and inhomogeneous plasma composition in the discharge cross section. The possibility of using of gliding discharge to ignite hydrocarbon-air mixtures in the ramjet engines combustors has been experimentally demonstrated.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"5 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Here, we propose and develop a silicon (Si)-based perovskite plasmon-emitting diode (PED) with controlled linear polarization in this study. Such polarization originates from the efficient excitation of surface plasmons by excitons in the active layer of the device and the efficient outcoupling by a wedged boundary of a metal electrode. Furthermore, a p-type Si substrate serves as an anode of the diode, and a hole blocking layer of SiO2 is introduced in the PEDOT:PSS/Si heterojunction for carrier injection balance. Pure green emission light has been achieved from devices with varied thicknesses of the emitting layer, and the maximum degree of polarization is measured to be 0.79. The field distribution and polarization of the PED were simulated and measured. Such a low-cost Si-based plasmonic diode provides a promising way to realize simpler and more compact multiple-functional light sources, which are extensively demanded for optoelectronic integration.
{"title":"Silicon-based perovskite plasmonic diode with highly polarized emission","authors":"Xin-Rui Mao, Zihao Chu, Xiaogen Yi, Riyu Cong, Yanping Li, Wanjin Xu, Guangzhao Ran","doi":"10.1088/1361-6463/ad7037","DOIUrl":"https://doi.org/10.1088/1361-6463/ad7037","url":null,"abstract":"Here, we propose and develop a silicon (Si)-based perovskite plasmon-emitting diode (PED) with controlled linear polarization in this study. Such polarization originates from the efficient excitation of surface plasmons by excitons in the active layer of the device and the efficient outcoupling by a wedged boundary of a metal electrode. Furthermore, a p-type Si substrate serves as an anode of the diode, and a hole blocking layer of SiO<sub>2</sub> is introduced in the PEDOT:PSS/Si heterojunction for carrier injection balance. Pure green emission light has been achieved from devices with varied thicknesses of the emitting layer, and the maximum degree of polarization is measured to be 0.79. The field distribution and polarization of the PED were simulated and measured. Such a low-cost Si-based plasmonic diode provides a promising way to realize simpler and more compact multiple-functional light sources, which are extensively demanded for optoelectronic integration.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"60 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In pursuit of diamond nanoparticles, a capacitively-coupled radio frequency flow-through plasma reactor was operated with methane-argon gas mixtures. Signatures of the final product obtained microscopically and spectroscopically indicated that the product was an amorphous form of graphite. This result was consistent irrespective of combinations of the macroscopic reactor settings. To explain the observed synthesis output, measurements of C2 and gas properties were carried out by laser-induced fluorescence and optical emission spectroscopy. Strikingly, the results indicated a strong gas temperature gradient of 100 K per mm from the center of the reactor to the wall. Based on additional plasma imaging, a model of hot constricted region (filamentation region) was then formulated. It illustrated that, while the hot constricted region was present, the bulk of the gas was not hot enough to facilitate diamond sp3 formation: characterized by much lower reaction rates, when compared to sp2, sp3 formation kinetics are expected to become exponentially slow. This result was further confirmed by experiments under identical conditions but with a H2/CH4 mixture, where no output material was detected: if graphitic sp2 formation was expected as the main output material from the methane feedstock, atomic hydrogen would then be expected to etch it away in situ, such that the net production of that sp2-hybridized solid material is nearly a zero. Finally, the crucial importance of gas heating was corroborated by replacing RF with microwave source whereby facile sp3 production was attained with H2/CH4 gas mixture.
{"title":"Importance of gas heating in capacitively coupled radiofrequency plasma-assisted synthesis of carbon nanomaterials","authors":"Tanvi Nikhar, Sankhadeep Basu, Shota Abe, Shurik Yatom, Yevgeny Raitses, Rebecca Anthony, Sergey V Baryshev","doi":"10.1088/1361-6463/ad6d78","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6d78","url":null,"abstract":"In pursuit of diamond nanoparticles, a capacitively-coupled radio frequency flow-through plasma reactor was operated with methane-argon gas mixtures. Signatures of the final product obtained microscopically and spectroscopically indicated that the product was an amorphous form of graphite. This result was consistent irrespective of combinations of the macroscopic reactor settings. To explain the observed synthesis output, measurements of C<sub>2</sub> and gas properties were carried out by laser-induced fluorescence and optical emission spectroscopy. Strikingly, the results indicated a strong gas temperature gradient of 100 K per mm from the center of the reactor to the wall. Based on additional plasma imaging, a model of hot constricted region (filamentation region) was then formulated. It illustrated that, while the hot constricted region was present, the bulk of the gas was not hot enough to facilitate diamond <italic toggle=\"yes\">sp</italic><sup>3</sup> formation: characterized by much lower reaction rates, when compared to <italic toggle=\"yes\">sp</italic><sup>2</sup>, <italic toggle=\"yes\">sp</italic><sup>3</sup> formation kinetics are expected to become exponentially slow. This result was further confirmed by experiments under identical conditions but with a H<sub>2</sub>/CH<sub>4</sub> mixture, where no output material was detected: if graphitic <italic toggle=\"yes\">sp</italic><sup>2</sup> formation was expected as the main output material from the methane feedstock, atomic hydrogen would then be expected to etch it away <italic toggle=\"yes\">in situ</italic>, such that the net production of that <italic toggle=\"yes\">sp</italic><sup>2</sup>-hybridized solid material is nearly a zero. Finally, the crucial importance of gas heating was corroborated by replacing RF with microwave source whereby facile <italic toggle=\"yes\">sp</italic><sup>3</sup> production was attained with H<sub>2</sub>/CH<sub>4</sub> gas mixture.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"7 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Perfluoroisobutyronitrile (C4F7N) gas mixture is considered one of the most promising alternative gases for SF6 due to its excellent environmental protection and insulation performance. At present, the Shanghai region of China has adopted 8.5% C4F7N-86% CO2-5.5% O2 proportion gas mixture as the insulation medium for 126 kV gas insulated switchgear and has put it into practical engineering application. This paper conducted decomposition experiments on the proportion gas mixture under spark discharge, suspension discharge, and corona discharge conditions, respectively. The composition analysis of the decomposition products was carried out using a gas chromatography mass spectrometry and a gas chromatography-pulsed discharge helium ionization detector, which got decomposition products of the C4F7N/CO2/O2 gas mixture under discharge faults mainly include CO, CF4, C3F8, C4F8, C3F6, and CF3CN. According to the decomposition path of the C4F7N gas mixture, this paper selected three primary decomposition products (CO, CF4, C3F8) and one secondary decomposition product (C4F8) for the correlation characterization of discharge types, and proposed the ratios of c(CO)/c(CF4) and c(C4F8)/c(C3F8) as the characteristic quantities to characterize the different discharge types. Finally, in order to accurately identify the C4F7N/CO2/O2 gas mixture discharge type, this paper chose the decision tree algorithm to build a identification tree. The final identification result indicates that the ratio of c (CO)/c (CF4) and c (C4F8)/c (C3F8) can be used as the identification criterion for typical discharge fault types.
{"title":"Discharge fault type identification of C4F7N/CO2/O2 mixed insulating gas for engineering based on product components","authors":"Guangkai Cui, Cong Wang, Yuan Yang, Hao Wang, Youping Tu, Zhong Zheng, Hua Jin","doi":"10.1088/1361-6463/ad714c","DOIUrl":"https://doi.org/10.1088/1361-6463/ad714c","url":null,"abstract":"Perfluoroisobutyronitrile (C<sub>4</sub>F<sub>7</sub>N) gas mixture is considered one of the most promising alternative gases for SF<sub>6</sub> due to its excellent environmental protection and insulation performance. At present, the Shanghai region of China has adopted 8.5% C<sub>4</sub>F<sub>7</sub>N-86% CO<sub>2</sub>-5.5% O<sub>2</sub> proportion gas mixture as the insulation medium for 126 kV gas insulated switchgear and has put it into practical engineering application. This paper conducted decomposition experiments on the proportion gas mixture under spark discharge, suspension discharge, and corona discharge conditions, respectively. The composition analysis of the decomposition products was carried out using a gas chromatography mass spectrometry and a gas chromatography-pulsed discharge helium ionization detector, which got decomposition products of the C<sub>4</sub>F<sub>7</sub>N/CO<sub>2</sub>/O<sub>2</sub> gas mixture under discharge faults mainly include CO, CF<sub>4</sub>, C<sub>3</sub>F<sub>8</sub>, C<sub>4</sub>F<sub>8</sub>, C<sub>3</sub>F<sub>6</sub>, and CF<sub>3</sub>CN. According to the decomposition path of the C<sub>4</sub>F<sub>7</sub>N gas mixture, this paper selected three primary decomposition products (CO, CF<sub>4</sub>, C<sub>3</sub>F<sub>8</sub>) and one secondary decomposition product (C<sub>4</sub>F<sub>8</sub>) for the correlation characterization of discharge types, and proposed the ratios of c(CO)/c(CF<sub>4</sub>) and c(C<sub>4</sub>F<sub>8</sub>)/c(C<sub>3</sub>F<sub>8</sub>) as the characteristic quantities to characterize the different discharge types. Finally, in order to accurately identify the C<sub>4</sub>F<sub>7</sub>N/CO<sub>2</sub>/O<sub>2</sub> gas mixture discharge type, this paper chose the decision tree algorithm to build a identification tree. The final identification result indicates that the ratio of c (CO)/c (CF<sub>4</sub>) and c (C<sub>4</sub>F<sub>8</sub>)/c (C<sub>3</sub>F<sub>8</sub>) can be used as the identification criterion for typical discharge fault types.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"34 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-30DOI: 10.1088/1361-6463/ad6e99
Irina Oganesyan, Alina Begley, Dušan Mrđenović, Julian A Harrison, Renato Zenobi
Plasma medicine is a field that utilizes reactive species generated from atmospheric low-temperature plasmas for applications such as sterilization, blood coagulation, and cancer therapy. Commercial plasma devices are available for wound healing, but research on the chemical modifications induced by these plasmas is scarce. This study explores the chemical modifications in hemoglobin when exposed to a helium plasma dielectric barrier discharge, with the aim of explaining the potential mechanisms through which it contributes to blood coagulation and enhances wound healing. Optical microscopy of cold atmospheric plasma (CAP) treated whole capillary blood showed an increase in red blood cell (RBC) size and the formation of rouleaux structures. The treatment of whole blood leads to hemolysis of RBCs and the release of intracellular protein content. We then treated purified hemoglobin protein at physiological concentrations, which led to the formation of aggregates that could be observed using ion mobility mass spectrometry (IM–MS), size exclusion chromatography, and optical microscopy. The aggregates formed fibril-like structures as observed using atomic force microscopy. The formation of hemoglobin aggregates is hypothesized to be the result of new intermolecular interactions formed following the CAP-mediated protein oxidation. We studied the changes to hemoglobin structure after treatment with a CAP using high-resolution MS and found that the hemoglobin subunits are oxidized with the addition of at least 4 oxygen atoms each. The intact tetrameric hemoglobin structure remains unchanged; however, the monomeric and dimeric proteins adopt a more compact structure, as observed by IM–MS. We propose that CAP treatment of fresh blood leads to hemolysis, and that the extracellular protein, primarily hemoglobin, is oxidized leading to the formation of aggregates.
等离子体医学是一个利用大气低温等离子体产生的反应物进行消毒、血液凝固和癌症治疗等应用的领域。目前已有用于伤口愈合的商用等离子体设备，但有关这些等离子体诱导的化学变化的研究却很少。本研究探讨了血红蛋白暴露于氦等离子体介质阻挡放电时的化学变化，旨在解释其促进血液凝固和促进伤口愈合的潜在机制。对冷大气等离子体（CAP）处理过的全毛细血管血液进行光学显微镜观察，结果显示红细胞（RBC）体积增大，并形成了胭脂红结构。处理全血会导致红细胞溶血，并释放出细胞内的蛋白质成分。然后，我们以生理浓度处理纯化的血红蛋白，从而形成了可通过离子迁移质谱法（IM-MS）、尺寸排阻色谱法和光学显微镜观察到的聚集体。使用原子力显微镜可观察到聚集体形成纤维状结构。据推测，血红蛋白聚集体的形成是 CAP 介导的蛋白质氧化后形成的新的分子间相互作用的结果。我们利用高分辨率质谱研究了使用 CAP 处理后血红蛋白结构的变化，发现血红蛋白亚基被氧化，每个亚基至少增加了 4 个氧原子。完整的四聚体血红蛋白结构保持不变；然而，正如 IM-MS 所观察到的，单体和二聚体蛋白采用了更紧凑的结构。我们认为，CAP 处理新鲜血液会导致溶血，细胞外蛋白质（主要是血红蛋白）被氧化，从而形成聚集体。
{"title":"Oxidative aggregation of hemoglobin–a mechanism for low-temperature plasma-mediated wound healing","authors":"Irina Oganesyan, Alina Begley, Dušan Mrđenović, Julian A Harrison, Renato Zenobi","doi":"10.1088/1361-6463/ad6e99","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6e99","url":null,"abstract":"Plasma medicine is a field that utilizes reactive species generated from atmospheric low-temperature plasmas for applications such as sterilization, blood coagulation, and cancer therapy. Commercial plasma devices are available for wound healing, but research on the chemical modifications induced by these plasmas is scarce. This study explores the chemical modifications in hemoglobin when exposed to a helium plasma dielectric barrier discharge, with the aim of explaining the potential mechanisms through which it contributes to blood coagulation and enhances wound healing. Optical microscopy of cold atmospheric plasma (CAP) treated whole capillary blood showed an increase in red blood cell (RBC) size and the formation of rouleaux structures. The treatment of whole blood leads to hemolysis of RBCs and the release of intracellular protein content. We then treated purified hemoglobin protein at physiological concentrations, which led to the formation of aggregates that could be observed using ion mobility mass spectrometry (IM–MS), size exclusion chromatography, and optical microscopy. The aggregates formed fibril-like structures as observed using atomic force microscopy. The formation of hemoglobin aggregates is hypothesized to be the result of new intermolecular interactions formed following the CAP-mediated protein oxidation. We studied the changes to hemoglobin structure after treatment with a CAP using high-resolution MS and found that the hemoglobin subunits are oxidized with the addition of at least 4 oxygen atoms each. The intact tetrameric hemoglobin structure remains unchanged; however, the monomeric and dimeric proteins adopt a more compact structure, as observed by IM–MS. We propose that CAP treatment of fresh blood leads to hemolysis, and that the extracellular protein, primarily hemoglobin, is oxidized leading to the formation of aggregates.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"20 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-30DOI: 10.1088/1361-6463/ad6fae
Céline Ruscher, Robinson Cortes-Huerto, Robert Hannebauer, Debashish Mukherji, Alireza Nojeh, A Srikantha Phani
Using large scale molecular dynamics simulations, we study the thermal conductivity of bare and surface passivated silicon nanowires (SiNWs). For the cross–sectional widths w⩽2 nm, SiNWs become unstable because of the surface amorphization and also due to the evaporation of a certain fraction of Si atoms. The observed surface (in–)stability is related to a large excess energy Δ of the surface Si atoms with respect to the bulk Si, resulting from the surface atoms being less coordinated and having dangling bonds. We first propose a practically relevant method that uses Δ as a guiding tool to passivate these dangling bonds with hydrogen or oxygen, stabilizing the SiNWs. These passivated SiNWs are used to calculate the thermal conductivity coefficient κ. While the expected trend of κ∝w is observed for all SiNWs, surface passivation provides an added flexibility of tuning κ with the surface coverage concentration c of passivated atoms. Indeed, with respect to the bulk κ, passivation of SiNW reduces κ by 75%–80% for c→50% and increases it by 50% for the fully passivated samples. Analyzing the phonon band structures via spectral energy density, we discuss separate contributions from the surface and the core to κ. Our results also reveal that surface passivation increases SiNW stiffness, contributing to the tunability in κ.
{"title":"Tuning the thermal conductivity of silicon nanowires by surface passivation","authors":"Céline Ruscher, Robinson Cortes-Huerto, Robert Hannebauer, Debashish Mukherji, Alireza Nojeh, A Srikantha Phani","doi":"10.1088/1361-6463/ad6fae","DOIUrl":"https://doi.org/10.1088/1361-6463/ad6fae","url":null,"abstract":"Using large scale molecular dynamics simulations, we study the thermal conductivity of bare and surface passivated silicon nanowires (SiNWs). For the cross–sectional widths <inline-formula>\u0000<tex-math><?CDATA $w unicode{x2A7D} 2$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mi>w</mml:mi><mml:mtext>⩽</mml:mtext><mml:mn>2</mml:mn></mml:mrow></mml:math><inline-graphic xlink:href=\"dad6faeieqn1.gif\"></inline-graphic></inline-formula> nm, SiNWs become unstable because of the surface amorphization and also due to the evaporation of a certain fraction of Si atoms. The observed surface (in–)stability is related to a large excess energy Δ of the surface Si atoms with respect to the bulk Si, resulting from the surface atoms being less coordinated and having dangling bonds. We first propose a practically relevant method that uses Δ as a guiding tool to passivate these dangling bonds with hydrogen or oxygen, stabilizing the SiNWs. These passivated SiNWs are used to calculate the thermal conductivity coefficient <italic toggle=\"yes\">κ</italic>. While the expected trend of <inline-formula>\u0000<tex-math><?CDATA $kappa propto w$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mi>κ</mml:mi><mml:mo>∝</mml:mo><mml:mi>w</mml:mi></mml:mrow></mml:math><inline-graphic xlink:href=\"dad6faeieqn2.gif\"></inline-graphic></inline-formula> is observed for all SiNWs, surface passivation provides an added flexibility of tuning <italic toggle=\"yes\">κ</italic> with the surface coverage concentration <italic toggle=\"yes\">c</italic> of passivated atoms. Indeed, with respect to the bulk <italic toggle=\"yes\">κ</italic>, passivation of SiNW reduces <italic toggle=\"yes\">κ</italic> by 75%–80% for <inline-formula>\u0000<tex-math><?CDATA $c to 50%$?></tex-math><mml:math overflow=\"scroll\"><mml:mrow><mml:mi>c</mml:mi><mml:mo accent=\"false\" stretchy=\"false\">→</mml:mo><mml:mn>50</mml:mn><mml:mi mathvariant=\"normal\">%</mml:mi></mml:mrow></mml:math><inline-graphic xlink:href=\"dad6faeieqn3.gif\"></inline-graphic></inline-formula> and increases it by 50% for the fully passivated samples. Analyzing the phonon band structures via spectral energy density, we discuss separate contributions from the surface and the core to <italic toggle=\"yes\">κ</italic>. Our results also reveal that surface passivation increases SiNW stiffness, contributing to the tunability in <italic toggle=\"yes\">κ</italic>.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"11 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-29DOI: 10.1088/1361-6463/ad7148
Fengming Yang, Wencong Zhang, Kama Huang, Yang Yang, Huacheng Zhu
The microwave-to-plasma energy conversion efficiency and the ease of plasma self-ignition are critical factors affecting the applications for microwave plasma sources (MPSs). This study presents a novel MPS utilizing dielectric wedges for self-ignition and improved energy conversion. Firstly, we crafted a dielectric wedge with a gradient refractive index, guiding the electric field from air to dielectric materials and facilitating microwave propagation along the dielectric in a waveguide. Through electromagnetic simulation, we explored how the size and permittivity of the dielectric wedge affect the electric field distribution. Then, the MPS based on the dielectric wedge was designed. In this configuration, a dielectric tube encloses the discharge tube, connecting to dielectric wedges to guide electromagnetic waves to the plasma. We analyzed the MPS performance using the Drude model, evaluating microwave energy conversion efficiency across various electron densities and collision frequencies. The results were compared with a commonly used MPS based on a tapered waveguide, demonstrating the proposed MPS has wider applicability across different operation conditions. Finally, experiments under low pressures were conducted using various gases, showing an average energy conversion efficiency of approximately 40% higher than the tapered waveguide MPS. The experiments also indicate the proposed MPS has a greater capability of self-ignition at lower power levels. These findings highlight the efficacy of incorporating dielectric wedges to enhance MPS performance, making it conducive for broader industrial applications.
{"title":"A high-performance microwave plasma source employing dielectric wedges","authors":"Fengming Yang, Wencong Zhang, Kama Huang, Yang Yang, Huacheng Zhu","doi":"10.1088/1361-6463/ad7148","DOIUrl":"https://doi.org/10.1088/1361-6463/ad7148","url":null,"abstract":"The microwave-to-plasma energy conversion efficiency and the ease of plasma self-ignition are critical factors affecting the applications for microwave plasma sources (MPSs). This study presents a novel MPS utilizing dielectric wedges for self-ignition and improved energy conversion. Firstly, we crafted a dielectric wedge with a gradient refractive index, guiding the electric field from air to dielectric materials and facilitating microwave propagation along the dielectric in a waveguide. Through electromagnetic simulation, we explored how the size and permittivity of the dielectric wedge affect the electric field distribution. Then, the MPS based on the dielectric wedge was designed. In this configuration, a dielectric tube encloses the discharge tube, connecting to dielectric wedges to guide electromagnetic waves to the plasma. We analyzed the MPS performance using the Drude model, evaluating microwave energy conversion efficiency across various electron densities and collision frequencies. The results were compared with a commonly used MPS based on a tapered waveguide, demonstrating the proposed MPS has wider applicability across different operation conditions. Finally, experiments under low pressures were conducted using various gases, showing an average energy conversion efficiency of approximately 40% higher than the tapered waveguide MPS. The experiments also indicate the proposed MPS has a greater capability of self-ignition at lower power levels. These findings highlight the efficacy of incorporating dielectric wedges to enhance MPS performance, making it conducive for broader industrial applications.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"438 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223060","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-29DOI: 10.1088/1361-6463/ad7152
Hucheng Liang, Boxue Du
Epoxy insulators in gas-insulated power apparatus are subjected to the combined effects of electrical and mechanical loads. In this work, a simulation model is built based on the energy theory to explore the electrical tree growth of epoxy resin under tensile and compressive stresses. With increasing AC voltage, the electrical tree growth is promoted, exhibiting a morphology with more branches. Tensile stress accelerates the electrical tree growth, while proper compressive stress has the opposite effect. However, when the compressive stress exceeds a certain value, electrical tree growth is promoted again. When the mechanical stress is vertical to the needle electrode, these effects primarily impact the length of the trees. Conversely, in parallel cases, mechanical stress mainly affects the width of the electrical trees. Filler doping play the role of obstacles as well as enhancing the electric field concentration, the electrical tree growth is firstly inhibited and then promoted as the doping content increases. The electrical tree morphologies of simulation and experiment are in good consistency, proving the reasonability of the simulation model.
{"title":"Simulation study on electrical tree propagation under electrical and mechanical stresses","authors":"Hucheng Liang, Boxue Du","doi":"10.1088/1361-6463/ad7152","DOIUrl":"https://doi.org/10.1088/1361-6463/ad7152","url":null,"abstract":"Epoxy insulators in gas-insulated power apparatus are subjected to the combined effects of electrical and mechanical loads. In this work, a simulation model is built based on the energy theory to explore the electrical tree growth of epoxy resin under tensile and compressive stresses. With increasing AC voltage, the electrical tree growth is promoted, exhibiting a morphology with more branches. Tensile stress accelerates the electrical tree growth, while proper compressive stress has the opposite effect. However, when the compressive stress exceeds a certain value, electrical tree growth is promoted again. When the mechanical stress is vertical to the needle electrode, these effects primarily impact the length of the trees. Conversely, in parallel cases, mechanical stress mainly affects the width of the electrical trees. Filler doping play the role of obstacles as well as enhancing the electric field concentration, the electrical tree growth is firstly inhibited and then promoted as the doping content increases. The electrical tree morphologies of simulation and experiment are in good consistency, proving the reasonability of the simulation model.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"22 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aramid fiber (AF)-reinforced epoxy (EP) resin composite materials are widely used in the application of insulation rod-reinforced components, but the adhesion performance between AFs and EP resin is poor, which easily leads to interfacial defects and even gradually develops into breakdown, flashover, and other faults. In this study, a simple, environmentally friendly, diverse, and highly designable layer-by-layer self-assembly modification method was adopted to assemble aramid nanofibers/SiO2 onto the surface of AFs. The modified AFs were then used to produce composite materials with EP resin. By testing the interface breakdown, flashover, and leakage current of the AF/EP resin composite materials, the influence mechanism of AF surface modification on the material interface insulation performance was studied. The results show that the insulation performance of the modified composite material first increases and then decreases with the increase in the number of assembled layers, with the maximum increase in breakdown voltage being 93.56% and the maximum increase in flashover voltage being 30.91%.
芳纶纤维（AF）增强环氧树脂（EP）复合材料在绝缘杆增强构件中应用广泛，但AF与EP树脂之间的粘附性能较差，容易导致界面缺陷，甚至逐渐发展为击穿、闪络等故障。本研究采用一种简单、环保、多样且可设计性强的逐层自组装改性方法，将芳纶纳米纤维/二氧化硅组装到 AFs 表面。改性后的 AFs 可用于生产 EP 树脂复合材料。通过测试 AF/EP 树脂复合材料的界面击穿、闪络和泄漏电流，研究了 AF 表面改性对材料界面绝缘性能的影响机理。结果表明，随着组装层数的增加，改性复合材料的绝缘性能先升后降，击穿电压的最大升幅为 93.56%，闪络电压的最大升幅为 30.91%。
{"title":"Effect characteristics of ANFs/SiO2 layer self-assembly on the insulation properties of aramid/epoxy composites","authors":"Jun Xie, Chengming Hu, Guowei Xia, Youzhi Zhang, Longyin Qiao, Bobin Xu, Xiaoyu Shi, Qing Xie","doi":"10.1088/1361-6463/ad714d","DOIUrl":"https://doi.org/10.1088/1361-6463/ad714d","url":null,"abstract":"Aramid fiber (AF)-reinforced epoxy (EP) resin composite materials are widely used in the application of insulation rod-reinforced components, but the adhesion performance between AFs and EP resin is poor, which easily leads to interfacial defects and even gradually develops into breakdown, flashover, and other faults. In this study, a simple, environmentally friendly, diverse, and highly designable layer-by-layer self-assembly modification method was adopted to assemble aramid nanofibers/SiO<sub>2</sub> onto the surface of AFs. The modified AFs were then used to produce composite materials with EP resin. By testing the interface breakdown, flashover, and leakage current of the AF/EP resin composite materials, the influence mechanism of AF surface modification on the material interface insulation performance was studied. The results show that the insulation performance of the modified composite material first increases and then decreases with the increase in the number of assembled layers, with the maximum increase in breakdown voltage being 93.56% and the maximum increase in flashover voltage being 30.91%.","PeriodicalId":16789,"journal":{"name":"Journal of Physics D: Applied Physics","volume":"61 1","pages":""},"PeriodicalIF":3.4,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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