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Materials possessing broadband antireflective properties benefit applications of military camouflage, photovoltaic devices, and highly transparent windows. In this work, large area, high throughput subdiffraction‐limited motheye‐like metastructures featuring broadband infrared (3–12 µm) antireflectivity are realized through dual‐beam overexposure shrinking strategy and subsequent controllable anisotropic reactive‐ion‐etching process. Both overexposure and overdevelopment processes severely controlled in conventional lithography processes, attribute significantly to improving linewidth resolution to <150 nm when photoresist thickness exceeding 500 nm, even to one micron. For antireflective application, the motheye profiles with customized anisotropic ratio (>3.27) and tunable taper‐angle range (>12.2°) are also realized by regulating the competition of directional ion bombardment and isotropic chemical etching in sulfur hexafluoride (SF6) plasma. The corresponding reflectivity is theoretically well‐simulated and experimentally validated after accounting for the tunable profiles and fractional volume coverage of motheye‐like structures. A low reflectivity <2.0% with the uniformity of ±4.8% and averaged to 1.2% across the overall spectrum of 3–12 µm are achieved. Implementing such efficient shrinking approach can possess huge potential in applications of military camouflage, photovoltaic devices, and highly transparent windows. [ABSTRACT FROM AUTHOR]

AbstractA critical limitation in developing portable Fourier transform-infrared (FTIR) stand-off chemical detectors is the library optimization which reduces the number of false alarms and maintains the performance. Ideally, a library should be established through high-resolution (0.5 cm−1) FTIR spectroscopy in the laboratory. However, due to the weight requirements of a portable FTIR stand-off detector, its optical system and mirror-moving range have limitations. Consequently, most portable FTIR stand-off detectors have been developed with a low resolution of approximately 4 to 16 cm−1. In this study, we developed a portable FTIR stand-off detector with a dual library of SF6. Moreover, we investigated its detection efficiency depending on the single library condition through realistic long-range (3 km) SF6 spectra in a field test. [ABSTRACT FROM AUTHOR]

Sulfur based deoxyfluorination reagents are usually derived from the corrosive gas SF4. Herein, we report the synthesis and properties of an easily accessible phosphonium salt [(tmg)3PF]+SF5− (1) which was obtained from the reaction of sulfur hexafluoride (SF6) with tris(tetramethylguanidinyl)phosphine. The performance of this crystalline SF5− salt as a reagent in deoxyfluorination reactions was investigated together with a second SF5− salt [(R1)3PF]+SF5− (2) containing bulky substituents (R1=1,3‐di‐tert‐butylimidazolidin‐2‐ylidenamino). Both reagents proved to be effective for the deoxyfluorination of various functional groups including alcohols, anhydrides, and amides. [ABSTRACT FROM AUTHOR]

As fluorine atoms significantly strengthen the metabolic stability and bioavailability of organic molecules, benzyl fluoride is found as an essential skeleton in pharmaceuticals or biologically active molecules. Here, we employ sulfur hexafluoride (SF6) as an efficient fluorinating reagent, achieving nucleophilic fluorination of widely available benzyl alcohols under visible LED light irradiation with a low dosage of photocatalyst 4CzIPN. The reaction is compatible with several substrate backbones and is not air- or moisture-sensitive, realizing the degradation and utilization of SF6, a potent greenhouse gas resource. [ABSTRACT FROM AUTHOR]

In Europe, respiratory protective devices must be certified before they can be marketed. Among the parameters of interest, inward leakage (IL) characterizes the tightness between the face seal and the face, to verify that the device is well-designed. European standard EN 13274-1 (2001) and International Organization for Standardization (ISO) standard ISO 16900-1 (2019) specify that IL should be measured using sodium chloride (NaCl) aerosol or sulfur hexafluoride (SF6) gas. For reusable masks made of nonporous materials, both test agents are considered equally acceptable. However, the few studies that have compared IL values measured with various aerosols and gases have come to divergent conclusions. This work then aimed to measure IL with the test agents recommended by the standards to determine whether they are really equivalent. Since krypton (Kr) is an interesting candidate for replacing SF6 in standard tests, IL was assessed with SF6 and Kr simultaneously, and with NaCl aerosol using various calculation methods. Tests were carried out on 5 models of full-face masks donned on a headform connected to a breathing machine simulating 3 sinusoidal breathing rates of various intensities. The respirator fit on the headform was evaluated using a controlled negative pressure method to determine a manikin fit factor. Four scenarios were then tested to represent very poor, bad, good, and excellent fit. Gas concentration was measured using a mass spectrometer, and IL was calculated for SF6 and Kr. A combination of 3 devices allowed the determination of the number-based concentration of particles with diameters between 20 nm and 2 µm, and IL was calculated for each of the 33 channels, as well as using a cumulative number concentration. In addition, to comply with standards, a conversion was carried out to calculate IL using a cumulative mass concentration. The results of this work evidenced that the IL values measured with NaCl were systematically lower than those determined with gases. IL was also shown to vary with particle size, with a maximum value exceeding that calculated with cumulative concentrations (in number or mass). As part of the revision of the standards, protocols for measuring inward leakage should be redefined. On the one hand, acceptability thresholds should be re-evaluated according to the nature of the test agent (gas or aerosol), as it is clear that the 2 options do not give the same results for a given configuration. On the other hand, the aerosol leakage measurement protocol needs to be reworked to enable the measurement of a well-defined, robust, and reproducible inward leakage value. [ABSTRACT FROM AUTHOR]

Examination of historical simulations from CMIP6 models shows substantial pre‐industrial to present‐day changes in ocean heat (ΔH), salinity (ΔS), oxygen (ΔO2), dissolved inorganic carbon (ΔDIC), chlorofluorocarbon‐12 (ΔCFC12), and sulfur hexafluoride (ΔSF6). The spatial structure of the changes and the consistency among models differ among tracers: ΔDIC, ΔCFC12, and ΔSF6 all are largest near the surface, are positive throughout the thermocline with weak changes below, and there is good agreement among the models. In contrast, the largest ΔH, ΔS, and ΔO2 are not necessarily at the surface, their sign varies within the thermocline, and there are large differences among models. These differences between the two groups of tracers are linked to climate‐driven changes in the ocean transport, with this tracer "redistribution" playing a significant role in changes in ΔH, ΔS, and ΔO2 but not the other tracers. The spatial structure, and differences between models, of changes in age tracers are consistent with ΔH, ΔS, and ΔO2, supporting the hypothesis that redistribution plays a major role for these tracers. Further, the impact of the vertical displacement of isopycnals (heave) plays a major role in the differing impact of redistribution between the two groups, with this process causing insignificant changes to ΔDIC, ΔCFC12, and ΔSF6 due to their weak spatial gradients. A similar multi‐tracer analysis of observations could provide insights into the relative role of the addition and redistribution of tracers in the ocean. Plain Language Summary: Changes in ocean properties can have a large impact on Earth's climate (e.g., ocean storage of heat and carbon) and biology within the oceans (e.g., acidification and deoxygenation). Here we examine historical changes in multiple ocean fields from an ensemble of climate model simulations. The spatial structure of the changes and the consistency among models differs between tracers. Dissolved inorganic carbon (DIC), chlorofluorocarbon‐12 (CFC12), and sulfur hexafluoride (SF6) all have largest increases near the surface, increase throughout the thermocline with weak changes below, and there is good agreement among the models. However, for ocean heat (H), salinity (S), oxygen (O2) the largest changes are not necessarily at the surface, the sign of the change varies among tracers, and there are large differences among models. These differences between the two groups of tracers are linked to climate‐driven changes in the ocean transport, with this tracer "redistribution" playing a significant role in changes in H, S, and O2 but not the other tracers. A similar multi‐tracer analysis of observations could provide insights into the relative role of the addition and redistribution of tracers in the ocean. Key Points: Historical changes in DIC, CFC12, and SF6 in CMIP6 simulations show similar spatial patterns and general agreement among the modelsHistorical changes in H, S, and O2 show regional differences, including in sign, among tracers and a wide variation among the modelsIncreases in surface values dominate changes in DIC, CFC12, and SF6, but changes in ocean transport are more crucial for H, S, and O2 [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to evaluate the performance and the impact of contrast-enhanced intraoperative ultrasound (CE-IOUS) on intraoperative decision-making, as there is still no standardized protocol for its use. Therefore, we retrospectively analyzed multiple CE-IOUS performed in hepato-pancreatic-biliary surgery with respect to pre- and postoperative imaging and histopathological findings. Methods: Data of 50 patients who underwent hepato-pancreatic-biliary surgery between 03/2022 and 03/2024 were retrospectively collected. CE-IOUS was performed with a linear 6–9 MHz multifrequency probe connected to a high-resolution device. The ultrasound contrast agent used was a stabilized aqueous suspension of sulphur hexafluoride microbubbles. Results: In total, all 50 lesions indicated for surgery were correctly identified. In 30 cases, CE-IOUS was used to localize the primary lesion and to define the resection margins. In the remaining 20 cases, CE-IOUS identified an additional lesion. Fifteen of these findings were identified as malignant. In eight of these cases, the additional malignant lesion was subsequently resected. In the remaining seven cases, CE-IOUS again revealed an inoperable situation. In summary, CE-IOUS diagnostics resulted in a high correct classification rate of 95.7%, with positive and negative predictive values of 95.2% and 100.0%, respectively. Conclusions: CE-IOUS shows excellent performance in describing intraoperative findings in hepato-pancreatic-biliary surgery, leading to a substantial impact on intraoperative decision-making. [ABSTRACT FROM AUTHOR]

In the present work, we report an update and extension of the previous ion-pair formation study of Hubers, M.M.; Los, J. Chem. Phys. 1975, 10, 235–259, noting new fragment anions from time-of-flight mass spectrometry. The branching ratios obtained from the negative ions formed in K + SF6 collisions, in a wide energy range from 10.7 up to 213.1 eV in the centre-of-mass frame, show that the main anion is assigned to SF5− and contributing to more than 70% of the total ion yield, followed by the non-dissociated parent anion SF6− and F−. Other less intense anions amounting to <20% are assigned to SF3− and F2−, while a trace contribution at 32u is tentatively assigned to S− formation, although the rather complex intramolecular energy redistribution within the temporary negative ion is formed during the collision. An energy loss spectrum of potassium cation post-collision is recorded showing features that have been assigned with the help of theoretical calculations. Quantum chemical calculations for the lowest-lying unoccupied molecular orbitals in the presence of a potassium atom are performed to support the experimental findings. Apart from the role of the different resonances participating in the formation of different anions, the role of higher-lying electronic-excited states of Rydberg character are noted. [ABSTRACT FROM AUTHOR]

The majority of reaction conditions employed in SF6 conversion research are characterized by elevated temperatures and pressures, resulting in a considerable expenditure of energy. The transformation of SF6 under mild conditions represents a viable methodology at this time. It has been demonstrated that the conditions required for the photoconversion of SF6 are relatively mild. Furthermore, the defect engineering of catalysts has been shown to be an effective strategy for enhancing the photocatalytic performance of photocatalysis. Thus, we utilized two-dimensional materials as a model for our research. These materials have active sites that are highly dense and uniform, allowing us to thoroughly examine how defects affect the SF6 photoconversion process. By synthesizing ZnO atomic layers with oxygen vacancies and confirming their presence using various techniques, we found that these vacancies enhanced light absorption and promoted the separation of charge carriers. These results suggest that the oxygen-deficient ZnO atomic layers have superior SF6 photoconversion performance compared to the pristine ZnO atomic layers. Overall, the findings of this study indicate that the incorporation of defects in photocatalysts is a crucial strategy for optimizing pivotal photocatalytic processes and enhancing the efficacy of SF6 photoconversion. We initially built clear models of two-dimensional atomic layers with defect concentrations, and hence directly disclose the defect type and distribution at atomic level. As a prototype, defective ZnO nanosheets with atomic thickness are successfully synthesized. Also, we use defective ZnO atomic layers to achieve light conversion of SF6 under mild conditions, which provides a new path to solve the environmental pollution of perfluorinated compounds. [ABSTRACT FROM AUTHOR]

To explore the efficacy and mechanisms of stimulating the nucleus accumbens (NAc) in heroin-addicted mice using focused ultrasound and microbubbles (MBs). The conditioned place preference (CPP) method was employed to establish a heroin-addicted mice model. Mice were randomized into control (C), heroin (H), heroin + ultrasound (H + U) and H + U + MBs. Ultrasound (2 MHz fundamental frequency, 1.34 MPa peak-negative pressure, 1 MHz pulse repetition frequency, 5% duty cycle, 15 min/d, over 2 d) was applied to stimulate the NAc in the latter 2 groups. Whereas H + U + MBs received an injection of sulfur hexafluoride MBs during the stimulation. Subsequently, CPP scores, open-field test (OFT), and elevated plus-maze test (EPMT) were conducted to assess behavioral changes in addiction memory, anxiety and exercise status. HE staining was performed to detect pathological structures. Neurotransmitters such as dopamine (DA), serotonin (5-HT) and glutamate (Glu) were detected using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Transmission electron microscopy (TEM) was used to observe ultrastructural changes of synapses in NAc. Immunohistochemistry (IHC) was utilized to detect Cleaved Caspase-3 in the NAc region. Western blotting (WB) was used to detect the protein expression of Cleaved Caspase-3, Bax and Bcl-2 in NAc. HE staining showed small patches of erythrocyte exudation were observed in the NAc and adjacent areas in H + U + MBs. The CPP scores of H + U + MBs were lower (p < 0.05) than H. After ultrasound treatment, all indices of the OFT and EPMT in H + U + MBs were significantly higher than H (p < 0.05). UPLC-MS/MS revealed that the levels of DA, 5-HT and Glu in H + U + MBs were lower than H (p < 0.01). TEM showed decrease the number of synapses (p < 0.05), and noticeable swelling of mitochondria, membrane damage, as well as damage to the cristae. Further detection by IHC and WB showed that the pro-apoptotic proteins Cleaved Caspase-3 and Bax increased and Bcl-2 decreased as anti-apoptotic proteins after ultrasound combined with MBs (p < 0.05). Focused ultrasound combined with MBs stimulate the NAc can weaken the addictive memory and improve anxiety of heroin-related mice. The mechanical effect of ultrasound combined with the cavitation effect may be a potential treatment for addiction. [ABSTRACT FROM AUTHOR]

A visible‐light‐induced strategy utilizing sulfur hexafluoride (SF6) as distinctive oxidant and water as the oxygen source to transform silanes into siloxanes has been developed under mild conditions, realizing the efficient utilization and degradation of the strong greenhouse gas, sulfur hexafluoride, simultaneously. Mechanistic experiments demonstrate that the reaction proceeds through a radical pathway, and it has been confirmed that the oxygen atoms in the resulting siloxanes indeed originate from water by isotopic labeling experiments with 18O. [ABSTRACT FROM AUTHOR]

Heptafluoro-iso-butyronitrile (i-C3F7CN) represents a feasible eco-friendly replacement gas for the most potent greenhouse gas sulfur hexafluoride in various high-voltage power transmission equipment. The reaction mechanisms for the in situ synthesis of i-C3F7CN from heptafluoro-iso-butyramide [i-C3F7C(O)NH2] in the presence of trifluoroacetic anhydride (TFAA) and pyridine (Py) in dimethylformamide solution have been studied within density functional theory with M06-2X exchange–correlation functional with the 6-311++G(d,p) basis set and the high-level ab initio complete basis set quadratic CBS-QB3 method. It is revealed that the unimolecular dehydration of i-C3F7C(O)NH2 can be catalyzed efficiently by TFAA in terms of both kinetic and thermodynamic aspects, producing i-C3F7CN and trifluoroacetic acid (TFA). Furthermore, Py is capable of reducing the energy barrier of the rate-determining step through hydrogen abstraction to form pyridinium hydrogen. The synergic effect of the TFAA/Py co-catalyst plays a pivotal role in the production of i-C3F7CN as the Gibbs free energy barrier can be lowered by more than 40 kcal/mol with the ratio of TFAA:2Py, in accordance with the experimental observation. The present theoretical work provides new insights into the rational design on the novel catalysts for large-scale synthesis of the perfluorinated nitriles. [ABSTRACT FROM AUTHOR]

Introduction: Valsalva retinopathy can cause submacular hemorrhage (SMH), which may lead to visual disturbances. SMH can extend into the subinternal limiting membrane (ILM) and vitreous spaces, sometimes occurring concomitantly with full‐thickness macular holes (FTMHs). Herein, we describe a case in which sub‐ILM hemorrhage was removed without peeling the ILM of the central fovea, thus preserving the foveal ILM. Case Presentation: A 48‐year‐old female patient developed rapid‐onset bilateral visual impairment due to SMH secondary to Valsalva retinopathy. The SMH predominantly consisted of sub‐ILM hemorrhage. However, detailed observation was challenging due to the dense sub‐ILM hemorrhage in the left eye. Initial best‐corrected visual acuity (BCVA) in the right and left eyes were 1.2 and 0.03, respectively. Intravitreal tissue plasminogen activator (tPA) and sulfur hexafluoride (SF6) gas injections were initially administered to displace the SMH in the left eye; however, the SMH could not be successfully displaced. A vitrectomy was then performed. Intraoperatively, an ILM fissure beyond the foveal region was created using ILM forceps. The balanced salt solution was sprayed onto the ILM, and the sub‐ILM hemorrhage was drained into the vitreous cavity from the ILM fissure. The surgery successfully displaced the sub‐ILM hemorrhage while preserving the foveal ILM. No postoperative complications were observed. Visual acuity remained at 1.2 in the right eye and improved to 1.2 in the left eye 6 months postoperatively. Conclusion: Removing foveal sub‐ILM hemorrhage without peeling the foveal ILM can be a viable treatment option to preserve the foveal ILM. [ABSTRACT FROM AUTHOR]

As one of the most potent greenhouse gases, SF6 has a significant economic and environmental impact on the purification and recovery of exhaust gases from the semiconductor industry. The adsorption and separation performance of SF6 on a two‐dimensional covalent organic framework TAT‐COFs‐1‐AB with different functional groups (SO3H, Et, NH2, OMe, OH, H) was investigated by using grand canonical Monte Carlo (GCMC) simulations and density functional theory (DFT) calculations. The results show that the adsorption at low pressure depends on the interactions between the SF6 and COF frameworks, while at high pressure it is mainly affected by the porosity. The highest adsorption capacity of 8.44 mmol/g (298 K, 100 kPa) is exhibited by TAT‐COF‐1‐AB‐H, which has the highest porosity. Chemical functionalization was found to be effective in enhancing the SF6/N2 selectivity. Among all the functionalized COFs, TAT‐COF‐1‐AB‐NH2, with the highest specific surface area and strong heat of adsorption, showed the highest selectivity. The simulation of self‐diffusion also shows consistent results with the GCMC simulation. The findings highlight that the adsorption capacity is influenced by substituent and porosity, with SF6 showing a consistent preference for adsorption at hollow sites, as evidenced by binding energy and charge transfer analyses. [ABSTRACT FROM AUTHOR]

SF6 is a strong greenhouse effect gas, which is widely used in high-voltage electrical equipment such as circuit breakers and high-voltage switchgear because of its excellent insulation performance and arc extinguishing ability. In recent years, the use and emission of SF6 have been rising, and with the proposal of the dual carbon strategic goal, its harmless degradation has become an urgent problem to be solved. In this paper, SF6 was degraded by pulsed DBD plasma technology and O2. Studies have shown that the addition of O2 can effectively promote the degradation of SF6. With the increase in the added O2 content, the DRE and EY of SF6 first increased and then decreased. Under the conditions of the input power of 50 W, SF6 concentration of 2%, and gas flow rate of 50 mL/min, the reaction system obtained the highest DRE and EY of 58.40% and 5.24 g/kWh when the O2 content was 1%, respectively. In the SF6/Ar/O2/H2O system, the addition of H2O could improve the product selectivity of SO2F2, and when the O2 concentration was 1%, the highest selectivity of SO2F2 was 48.96%, and the concentration was 8006.76 ppm. The addition of O2 inhibited the production of SO2, and with the addition of the O2 system, SO2F2 and SOF4 were the main components of degradation products; however, there were also SOF2, SO2, SiF4, SF4, etc. In this paper, the decomposition path of O2 under SF6 was analyzed in detail according to infrared spectroscopy and decomposition products. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the sulfur hexafluoride (SF6) tracer technique for estimating methane (CH4) emissions in dual-flow continuous culture systems (DFCCS). In experiment 1 (Exp1), fermenters were filled with water, and known CH4 concentrations (0, 1.35, 2.93, or 4.43 g/d) were injected using permeation tubes with SF6 release rates (3.30 or 9.65 mg/d). Headspace gas was collected using canisters, and the SF6 technique estimated CH4 recovery. Experiment 2 (Exp2) involved a DFCCS fermentation trial with ruminal fluid from three Holstein cows, testing diets with soybean meal or its partial replacement (50%) by Chlorella or Spirulina. Headspace gas was collected at intervals post-feeding. Standard curves for SF6 and CH4 quantification were inadequate for DFCCS samples, with the CH4:SF6 ratio differing from standards, indicating the data needs further SF6 release rate evaluation. In Exp1, a high correlation (r = 0.97) was found between infused and calculated CH4, indicating good repeatability. Low and high SF6 rates performed similarly at low CH4 infusion, but high SF6 overestimated CH4 at high infusion. Exp2 showed CH4 emissions irrespective of SF6 rate and indicated reduced CH4 emissions and increased NDF degradation with algae-containing diets. Further evaluation of the SF6 tracer technique is warranted for DFCCS. [ABSTRACT FROM AUTHOR]

AbstractPurposeMethodsResultsConclusionThis study presents a novel sutureless closure approach for sclerotomies following pars plana vitrectomy (PPV) and assesses its efficacy and safety.A total of 142 eyes were included in the study. PPV procedures were performed using 23-gauge (23 G) or 25-gauge (25 G) systems. Preoperative characteristics, intraoperative findings, and postoperative outcomes were documented.The cohort included 80 males and 62 females (mean age: 60.4 ± 12 years), primarily undergoing surgery for retinal detachment (59%). Among the patients, 87% underwent 25 G PPV (35% three-port, 52% four-port), while 13% underwent 23 G PPV (12% three-port, 1% four-port). Gas tamponade was administered in all cases, with perfluoropropane used in 45.7% of instances, sulfur hexafluoride in 29.5%, and air in 24.6%. Spontaneous closure was observed in 9.4% (47 of 501) of sclerotomies, autologous-fibrin induction approach successfully closed 75.8% (380 of 501) of the sclerotomies (83.7% of leaking sclerotomies) and 14.7% (74 of 501) of sclerotomies needed sutures. Visual acuity improved postoperatively, and first-day hypotony rate was 6.3%. Importantly, no serious complications such as choroidal detachment or endophthalmitis were observed during the postoperative period.The autologous-fibrin induction offers a simple, cost-efficient, and reliable approach for sutureless sclerotomy closure in PPV, with promising outcomes. [ABSTRACT FROM AUTHOR]

Background: The present study compares the anatomical and functional outcomes (best-corrected visual acuity (BCVA) and central macular thickness (CMT)) among membrane peeling with or without SF6 tamponade in patients with epiretinal membrane. Methods: We retrospectively reviewed patients diagnosed with macular pucker who underwent pars plana vitrectomy and membrane peeling in a tertiary center in Taiwan from January 2021 to December 2022. Subjects were categorized into with or without SF6 tamponade groups (SF6 group and BSS group). Postoperative intraocular pressure and complications were documented. Logistic regression analyses were performed to identify the prognostic factors during follow-up. Results: A total of 89 eyes were enrolled, including 34 eyes in the BSS group and 55 eyes in the SF6 group. The mean age was 66 years old, and a female predilection was demonstrated. Both groups possessed statistically significant improvement in BCVA and CMT after the operation. There was no significant difference in CMT between the groups at any time of observation, yet we observed significant differences in baseline BCVA and BCVA at last follow-up among the two groups. Both groups yielded an approximate enhancement of LogMAR 0.3 in BCVA postoperatively. There was no significant difference noted in postoperative IOP between the two groups. Conclusion: Membrane peeling with or without SF6 tamponade yields comparable outcomes anatomically and functionally. This may indicate that SF6 tamponade for idiopathic macular pucker surgery may not provide extra benefit, and therefore warrants reconsideration as standard procedure. [ABSTRACT FROM AUTHOR]

Background: Post-pneumonectomy syndrome (PPS) is a rare but serious condition that can occur after pneumonectomy. It is characterized by a mediastinal shift towards the vacated hemithorax, which can potentially lead to respiratory failure. The management of PPS poses a clinical challenge, especially in the context of the limited availability of certain therapeutic devices due to regulatory restrictions in Japan. Case presentation: A 36-year-old female with stage IB non-small cell lung cancer underwent left pneumonectomy. Approximately 2 years later, she developed dyspnea. After consulting with our hospital, subsequent imaging revealed an extreme mediastinal shift causing bronchial obstruction. Emergency thoracotomy and subsequent sulfur hexafluoride (SF6) injections were successfully used to manage her condition. Over the course of follow-up, the interval between SF6 injections was extended from 3 to 11 months, indicating an improvement in the intrathoracic condition. Conclusions: This case illustrates the efficacy of SF6 gas in treating PPS and in reducing the frequency of medical interventions. SF6 gas administration is safe and effective for the treatment of patients with PPS. [ABSTRACT FROM AUTHOR]

Purpose: To report a case of macular hole and detachment occurring after the subretinal injection of Voretigene Neparvovec (VN) in a patient affected by atypical RPE65 retinal dystrophy with high myopia and its successful surgical management. Case description: We report a case of a 70-year-old man treated with VN in both eyes. The best corrected visual acuity (BCVA) was 0.7 LogMar in the right eye (RE) and 0.92 LogMar in the left eye (LE). Axial length was 29.60 mm in the RE and 30.28 mm in the LE. Both eyes were pseudophakic. In both eyes, fundus examination revealed high myopia, posterior staphyloma, and extended retinal atrophy areas at the posterior pole, circumscribing a central island of surviving retina. Both eyes were treated with VN subretinal injection, but a full-thickness macular hole and retinal detachment occurred in the LE three weeks after surgery. The patient underwent 23-gauge vitrectomy with internal limiting membrane (ILM) peeling and the inverted flap technique with sulfur hexafluoride (SF6) 20% tamponade. Postoperative follow-up showed that the macular hole was closed and the BCVA was maintained. Conclusions: Our experience suggests that patients with atypical RPE65 retinal dystrophy and high myopia undergoing VN subretinal injection require careful management to minimize the risk of macular hole and detachment occurrence and promptly detect and address these potential complications. [ABSTRACT FROM AUTHOR]

Purpose: The visibility of biopsy needles in contrast-specific imaging mode can be improved by priming them with an ultrasound contrast agent (previously demonstrated in a phantom model/ex vivo). The purpose of this study was to validate this priming method in a porcine in vivo model. Materials and Methods: Using a small syringe, full-core biopsy needles were primed with sulfur hexafluoride, an ultrasound contrast agent, with non-primed needles serving as controls (n = 30 + 30). Liver punctures were performed in a porcine model following intravenous administration of the same ultrasound contrast agent. Needle visibility, both in their entirety and at the tips, was evaluated in split-screen mode using contrast-specific imaging and B-mode (low mechanical index). The assessment included quantitative analysis, calculating the contrast-to-noise ratio, and qualitative evaluation through structured grading by three radiologists. Results: After needle priming, the contrast-to-noise ratio was superior for the needle in its entirety in contrast-specific imaging mode (p < 0.001) and slightly inferior in B-mode (p = 0.008). No differences were observed for the needle tips in either imaging mode. Qualitatively, the needle visibility was deemed clinically superior after needle priming throughout in contrast-specific imaging mode (p < 0.001), whereas no clinically relevant differences in B-mode for either the needle in its entirety (p = 0.11) or the needle tip (p = 1) were observed. Conclusion: In this in vivo porcine liver model experiment, priming biopsy needles with ultrasound contrast agent improved needle visibility in contrast-specific imaging mode but slightly reduced it in B-mode. These findings support the method's use for biopsies requiring target visualization in contrast-specific imaging mode. No level of evidence. [ABSTRACT FROM AUTHOR]

In recent years, the C4F7N mixed gas has attracted considerable attention for its outstanding insulation and arc-extinguishing capabilities, positioning it as a potential substitute for sulfur hexafluoride, SF6. However, there remains a limited understanding of the arc-extinguishing and insulation performance of C4F7N/CO2 mixed gas. In addition, there is limited research on high-current breaking in circuit breakers. Therefore, this study aims to investigate the arc characteristics and breaking behavior of 10%C4F7N/90%CO2 and 15%C4F7N/85%CO2 mixed gases using a magnetohydrodynamic model based on the 252kV air pressure circuit breaker. The dynamic characteristics of this mixed gas are compared with pure SF6 under short-circuit current breaking conditions, while analyzing different parameters of the C4F7N configuration. The results indicate that the mixed gas exhibits lower levels in terms of arc temperature, axial diffusion distance and pressure difference at the moment of arc initiation compared to pure SF6. Furthermore, increasing the inflating pressure can effectively enhance the breaking performance of the circuit breaker with 0.6 MPa, making it more suitable. Additionally, increasing the proportion of C4F7N in the mixed gases will cause the arc temperature to rise slightly at the initial arc and current crossing zero, but decrease at the peak current. The core pressure also rises significantly, with a greater pressure difference established in the compressor at moment of arc initiation. This study provides a reference for the design of an environmentally friendly circuit breaker and the selection of the mixed gas ratio. [ABSTRACT FROM AUTHOR]

BACKGROUND: No studies have been retrieved comparing perfluorobutane with sulfur hexafluoride for microwave ablation (MWA) in small hepatocellular carcinoma(sHCC). OBJECTIVE: To retrospective investigate the value of perfluorobutane ultrasonography contrast agent in ultrasonography (US)-guided MWA of sHCC. METHODS: We conducted a retrospective clinical controlled study about US-guided percutaneous MWA in patients with sHCC, and in patients undergoing intra-operative treatment with perfluorobutane or sulfur hexafluoride. In both groups, a contrast agent was injected to clear the tumor and then a needle was inserted. A 5-point needle prick difficulty score was developed to compare needle prick difficulty in the two groups of cases. RESULTS: A total of 67 patients were included: 25 patients in group perfluorobutane, aged 41–82 (60.64±9.46), tumor size 1.1–2.8 (1.78±0.45) cm. 42 patients in group sulfur hexafluoride, aged 38–78 (62.26±9.27), with tumor size of 1.1–3.0 (1.89±0.49) cm. There was no significant difference in age or tumor size in both groups (P > 0.05). Puncture difficulty score (5-point): 2.0–2.7 (2.28±0.29) in group perfluorobutane, and 2.0–4.7 (2.95±0.85) in group sulfur hexafluoride, and the difference between the two groups was statistically significant (P < 0.05). Enhanced imaging results within 3 months after surgery: complete ablation rate was 100% (25/25) in the group perfluorobutane, 95.2% (40/42 in the group sulfur hexafluoride), with no significant difference between the two groups (P > 0.05). CONCLUSION: Perfluorobutane kupffer phase can make the operator accurately deploy the ablation needle and reduce the difficulty of operation. [ABSTRACT FROM AUTHOR]

Objectives: To assess the efficacy and safety of sulfur hexafluoride microbubbles on ultrasound-guided high-intensity focused ultrasound (HIFU) ablation of uterine fibroids. Methods: Studies that compared HIFU-microbubble combination with HIFU-only in patients with uterine fibroids were searched from inception to April 2022. The standardized mean difference (SMD) or relative risk (RR) with 95% confidence interval (CI) for different outcome parameters was calculated. Results: Seven studies were included, with a total of 901 patients (519 in the combination group and 382 in the HIFU-only group). The energy consumption for treating 1 cm3 of the lesion in the combination group was less than that in the HIFU-only group [SMD = − 2.19, 95%CI (− 3.81, − 0.57), p = 0.008]. The use of microbubbles was associated with shortening the duration of the treatment and sonication [SMD = − 2.60, 95%CI (− 4.09, − 1.10), p = 0.0007; SMD = − 2.11, 95%CI (− 3.30, − 0.92), p = 0.0005]. The rates of significant greyscale changes during HIFU were greater in the combination group, as well as the increase of non-perfused volume ratio [RR = 1.26, 95%CI (1.04, 1.54), p = 0.02; SMD = 0.32, 95%CI (0.03, 0.61), p = 0.03]. The average sonication durations to reach significant greyscale changes and for ablating 1 cm3 of the fibroid lesion were shorter in the combination group [SMD = − 1.24, 95%CI (− 2.02, − 0.45), p = 0.002; SMD = − 0.22, 95%CI (− 0.42, − 0.02), p = 0.03]. The two groups had similar post-HIFU adverse effects, while the combination group had fewer intraprocedural adverse events like abdominal pain, sacrum pain, and leg pain. Conclusions: Sulfur hexafluoride microbubbles can be safely used to enhance and accelerate the ablation effects of HIFU in the treatment of uterine fibroids. Clinical relevance statement: The combination of HIFU with sulfur hexafluoride microbubbles offers a promising non-invasive treatment option for patients with uterine fibroids. Key Points: • Sulfur hexafluoride microbubbles combined with ultrasound-guided high-intensity focused ultrasound (USgHIFU) has potential advantages in the treatment of uterine fibroids. • Sulfur hexafluoride microbubbles not only enhance the effects of USgHIFU treatment for uterine fibroids but also shorten its duration. • Sulfur hexafluoride microbubbles do not increase the incidence of USgHIFU-related adverse events in the treatment of uterine fibroids. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to describe the management of a hemorrhagic bacillary layer detachment (BALAD) in a patient with neovascular age-related macular degeneration. Methods: The clinical records and imaging were reviewed. Results: A 74-year-old woman presented with acute-onset hemorrhagic neovascular age-related macular degeneration with a large hemorrhagic BALAD. The intra-BALAD hemorrhage was amenable to displacement with SF6 pneumatic displacement with subsequent VA recovery. Conclusion: Sulfur hexafluoride (SF6) pneumatic displacement in combination with aflibercept injection is a viable means by which to manage a hemorrhagic BALAD in the context of neovascular age-related macular degeneration. Displacement of large intra-BALAD hemorrhages can result in good visual recovery. [ABSTRACT FROM AUTHOR]

Cellulose pulps in cementitious matrix have been investigated because of their high tensile strength, which improves the mechanical properties of the composites. Nonetheless, the material's hydrophilic nature could impair cement and potentially diminish the durability of the compound. In this work, to improve physical-mechanical performance of fiber cement produced with cellulose, the surface of the cellulose pulp was modified by sulfur hexafluoride (SF6) plasma treatment at different conditions (0.1, 0.3, 0.5 and 0.7 Torr). Fiber cement composite was subsequently produced from treated pulps. Theoretical calculations suggested that cellulose interacts with SF6 molecules through adsorption. The cellulose pulps were evaluated using spectroscopy, diffractometry and water affinity techniques. The physical and mechanical properties of the composites produced were evaluated before and after accelerated ageing cycles. The surface modification of cellulose pulp by SF6 plasma treatment was viable and suitable. FTIR and Raman spectroscopy showed the presence of specific bands related to C-Fx bonds. An exchange of behavior of the cellulose pulp occurred, transitioning from hydrophilic to hydrophobic. After 192 hours of analysis, moisture absorption was reduced by 15.28%, 13.99%, 8.30%, and 14.05% for the 0.1SF6, 0.3SF6, 0.5SF6, and 0.7SF6 treatments, respectively. Only the 0.1SF6 treatment yielded satisfactory results for all mechanical properties assessed, including rupture modulus (MOR), elasticity modulus (MOE), limit of proportionality (LOP), and toughness, when compared to untreated cellulose pulp. The positive results were particularly evident following accelerated ageing cycles, as the properties were either maintained (MOR, LOP) or improved (MOE, toughness). Therefore, this treatment is recommended for the intended application. [ABSTRACT FROM AUTHOR]

Helium (He) tracer method is one of the common methods used to detect tube bundle leakage in the condenser. To improve the detection accuracy, sulfur hexafluoride (SF6) is considered a tracer gas instead of He. This paper combines the N-S equation, porous medium model, flow diffusion model and steam heat transfer model to develop the numerical model of tube bundle leakage in the condenser. The simulation results show that the transport of leaked gases (He and SF6) consists of flow and diffusion patterns. The existence of the diffusion process is confirmed further through theoretical analysis. The two gases have the same transport behavior in the pure flow process. When it involves the diffusion process, the flow rate of He is 6.67 times that of SF6. In other words, the time required for He to reach the same concentration difference is 1/6.67 times that of SF6. In addition, the influence of leakage intensity and gas species on the transport is analyzed. The study results provide a theoretical basis for SF6 to replace He as a tracer gas to detect tube bundle leakage. [ABSTRACT FROM AUTHOR]

With an inherent lowest density and distinct solubility with enhanced mechanical behavior reason, the magnesium alloy composite is extensively used in the auto and aero sectors. The processing of magnesium alloy found micro‐cracks and voids between the oxidation spot, which fails properties. Through the sulfur hexafluoride (SF6) atmosphere, the AZ91D alloy hybrid nanocomposites are synthesized with 10 wt% alumina (Al2O3) and 0, 3, 6, and 9 wt% of silicon carbide (SiC) nanoparticles via a liquid state process with 400 rpm stir speed followed by vacuum die casting. The effect of SiC actions on physical behavior, microstructural formation, and mechanical properties of AZ91D/10 wt%Al2O3, AZ91D/10 wt%Al2O3/3 wt% SiC, AZ91D/10 wt% Al2O3/6 wt% SiC, and AZ91D/10 wt% Al2O3/9 wt% SiC composites are studied and its results compared with cast AZ91D alloy. Due to the actions of SiC in AZ91D/10 wt%Al2O3, the composite density conforms to the rule of mixture, and the void and micro‐cracks are limited (less than 1%) by the impact of the casting process, as evidenced in the microstructural illustration. An effect of 10 wt% Al2O3 and 9 wt% SiC contents in AZ91D facilitates maximum tensile strength of 181 MPa, improved elongation percentage of 2.2%, optimum hardness of 85HV, and superior impact toughness of 21.8 J/mm2, which is higher than the all other compositions. [ABSTRACT FROM AUTHOR]

Based on density functional theory (DFT), the effect of Pd3 cluster modification on the surface properties of PtSe2 monolayer and the gas sensitive detection performance of PtSe2/Pd3–PtSe2 on sulfur hexafluoride (SF6) decomposition is studied, in terms of the adsorption energy, density of states (DOS), and sensing characteristic. It is found that that the Pd3 cluster exhibit stable modified structure on monolayer PtSe2, the adsorption capacity of Pd3–PtSe2 monolayer is the highest, significantly improves the surface activity and sensing performance of PtSe2 monolayer. Further, the large charge transfer, bandgap, and conductivity changes indicate that the monolayer Pd3–PtSe2 has strong chemical interaction and high sensitivity to SO2, H2S, and SO2F2 gas molecules. Pd3–PtSe2 can be used as a potential candidate for gas sensors. Finally, the sensing performance analysis of the system shows that the recovery time of Pd3–PtSe2 for SO2F2 is only 10.7 s, which can be repeated for a long time. These analyses illustrate the potential application of Pd3–PtSe2 in the detection and removal of harmful gases in gas insulated switch‐gear (GIS). The calculations may provide new insights for researchers to explore gas‐sensitive materials based on PtSe2. [ABSTRACT FROM AUTHOR]

In view of the wide range of applications for ultra-sharp silicon (Si) nanocones, extensive research has been conducted on their fabrication processes. However, these conventional methods pose challenges in terms of achieving uniformity, controllability, and cost-efficiency. This study presents a novel approach to fabricating Si nanocone structures through reactive ion etching (RIE) using a tapered silicon dioxide mask, followed by thermal oxidation sharpening to reduce the apex diameter to 4 nm. Here the tapered SiO2 mask with a smooth sidewall was created through a combination of RIE and a buffered oxide etchant (BOE) etching. The lithography of the oxide mask is achieved using a cost-effective (compared to electron beam lithography) maskless aligner system (MLA). Subsequently, a non-switching pseudo-Bosch process, employing sulfur hexafluoride (SF6) gas and octafluorocyclobutane (C4F8) gas, is utilized for the etching the Si nanocone structures, resulting in an average apex diameter of 30 nm. Finally, thermal oxidation followed by oxide removal further sharpens these cones to 4 nm. [ABSTRACT FROM AUTHOR]

Sulphur hexafluoride is synthesised as a persistent and non-toxic gas with an exceptional dielectric strength. In contemporary medium-voltage switchgear within power distribution systems, SF6 gas is used for the insulation and the extinction of electric arc. The application of SF6 has advantages in terms of gas physicochemical characteristics and performance; the dimensions, the cost-effectiveness, the reliability of the switchgear equipment and the duration, as well as the cost of maintenance were significantly reduced. SF6 is a known greenhouse gas, which tends to accumulate in the lungs, inducing oxygen depletion and respiratory complications. The by-products of SF6 formed during the electric arc can be harmful and toxic. The equipment containing SF6 is being replaced in the EU and worldwide. Using ALOHA® software the scenarios of leakage for SF6 and by-products were modelled in urban areas, where the switchgear is frequently placed. In areas where the circulation of wind is lower (urban areas), in hazardous situations, it is not possible to depend on high dispersion levels or minimisation of concentration and threat. The models have shown that SF6 poses an environmental problem and its by-products cause a serious health hazard in the case of leakage in urban areas, rendering red threat zones from 10 to 60 m in radius. [ABSTRACT FROM AUTHOR]

Sulfur hexafluoride (SF6) is a typical fluorine gas with excellent insulation and arc extinguishing properties that has been widely used in large-scale power equipment. The detection of SF6 gas in high-power electrical equipment is a necessary measure to ensure the reliability and safety of power grid operation. A failure of SF6 insulated electrical equipment, such as discharging or overheating conditions, can cause SF6 gas decomposition, resulting in various decomposition products. The decomposed gases inside the equipment decrease the insulating properties and are toxic. The leakage of SF6 can also decrease the insulating properties. Therefore, it is crucial to monitor the leakage of SF6 decomposed gases from electrical equipment. Quantitative testing of decomposition products allows us to assess the insulation state of the equipment, identify internal faults, and maintain the equipment. This review comprehensively introduces the decomposition formation mechanism of SF6 gas and the current detection technology of decomposition products from the aspects of principle and structure, materials, test effect, and practicability. Finally, the development trends of SF6 and decomposition gas detection technology for the reliability and safety of power grid operation are prospected. [ABSTRACT FROM AUTHOR]

Silicon (Si) nanocones have a wide range of applications in microelectromechanical systems and nanoelectromechanical systems. There is an increasing demand for precise control over the size and shape of nanocones. This paper proposed a novel method combining Si dry etch with periodic oxygen plasma shrinking, wet etch, and oxidation sharpening to achieve well-defined sharp Si nanocones. First, the standard Bosch process was employed to create the base part of nanocones. Second, two alternating steps of etching with sulfur hexafluoride/octafluorocyclobutane plasma and photoresist shrinkage with oxygen plasma were used to form the cone-shaped structures on top of the cylindrical bases. Third, to obtain a sharp tip, wet etching was carried out in either potassium hydroxide or a nitric acid/hydrofluoric (HF) acid mixture. To further sharpen the Si tips, thermal oxidation and HF dipping were conducted and the apex of nanocones can be down to 20 nm. This technique provides a cost-effective way to manufacture nanocones for various applications. [ABSTRACT FROM AUTHOR]

The first-order phase transition between the liquid and gaseous phases ends at a critical point. Critical opalescence occurs at this singularity. Discovered in 1822, it is known to be driven by diverging fluctuations in the density. During the past two decades, boundaries between the gas-like and liquid-like regimes have been theoretically proposed and experimentally explored. Here, we show that fast cooling of near-critical sulfur hexafluoride (SF6), in presence of Earth's gravity, favors dark opalescence, where visible photons are not merely scattered, but also absorbed. When the isochore fluid is quenched across the critical point, its optical transmittance drops by more than three orders of magnitude in the whole visible range, a feature which does not occur during slow cooling. We show that transmittance shows a dip at 2eV near the critical point, and the system can host excitons with binding energies ranging from 0.5 to 4 eV. The spinodal decomposition of the liquid-gas mixture, by inducing a periodical modulation of the fluid density, can provide a scenario to explain the emergence of this platform for coupling between light and matter. The possible formation of excitons and polaritons points to the irruption of quantum effects in a quintessentially classical context. The first-order phase boundary between the liquid and gaseous phases ends at a critical point where the fluid, kept at thermodynamic equilibrium, displays a turbidity known as 'critical opalescence'. The authors quench a fluid across its critical point, find blackness instead of turbidity, and argue that, out of equilibrium, photons can be absorbed, not merely scattered. [ABSTRACT FROM AUTHOR]

The first-order phase transition between the liquid and gaseous phases ends at a critical point. Critical opalescence occurs at this singularity. Discovered in 1822, it is known to be driven by diverging fluctuations in the density. During the past two decades, boundaries between the gas-like and liquid-like regimes have been theoretically proposed and experimentally explored. Here, we show that fast cooling of near-critical sulfur hexafluoride (SF6), in presence of Earth's gravity, favors dark opalescence, where visible photons are not merely scattered, but also absorbed. When the isochore fluid is quenched across the critical point, its optical transmittance drops by more than three orders of magnitude in the whole visible range, a feature which does not occur during slow cooling. We show that transmittance shows a dip at 2eV near the critical point, and the system can host excitons with binding energies ranging from 0.5 to 4 eV. The spinodal decomposition of the liquid-gas mixture, by inducing a periodical modulation of the fluid density, can provide a scenario to explain the emergence of this platform for coupling between light and matter. The possible formation of excitons and polaritons points to the irruption of quantum effects in a quintessentially classical context. The first-order phase boundary between the liquid and gaseous phases ends at a critical point where the fluid, kept at thermodynamic equilibrium, displays a turbidity known as 'critical opalescence'. The authors quench a fluid across its critical point, find blackness instead of turbidity, and argue that, out of equilibrium, photons can be absorbed, not merely scattered. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal CrystEngComm, which focuses on the design and understanding of solid-state and crystalline materials. The list includes various papers on topics such as hybrid materials, growth of single-crystalline particles, high-pressure phase transitions, coordination polymers, and optical properties of crystals. The journal is published by The Royal Society of Chemistry, a leading chemistry community. The document also mentions professional recognition and development opportunities for scientists. [Extracted from the article]

The assembly of a metal–organic framework (MOF) containing bent phenanthroline linkers and iron trinuclear clusters remains rare. Herein, we report the synthesis and single crystal structure of a two-dimensional (2D) MOF, Fe-cage-MOF, assembled from 2,9-substituted phenanthroline based carboxylate linkers and pre-synthesized iron trinuclear clusters. The distinctive octahedral cages and ordered 1D channels endow the MOF with permanent porosity and potential for selective capture of the greenhouse gas sulfur hexafluoride. [ABSTRACT FROM AUTHOR]

Ultrasound enhancing agents (UEAs) are medications that enable clear visualization of ultrasound images. While large studies have demonstrated the safety of these agents, case reports of life-threatening reactions temporally associated with their use have been published and reported to the Food and Drug Administration. Current literature describes the most serious adverse reactions due to UEAs to be allergic in nature; however, embolic phenomena may play a role as well. Here, we report a case of unexplained cardiac arrest following the administration of sulfur hexafluoride (Lumason®) in an adult inpatient undergoing echocardiography where resuscitative efforts were ultimately unsuccessful, and review possible mechanisms of cardiac arrest based on prior published literature. [ABSTRACT FROM AUTHOR]

Subharmonic aided pressure estimation (SHAPE) is a noninvasive pressure measurement technique based on the pressure dependent subharmonic signal from contrast microbubbles. Here, SonoVue microbubble with a sulfur hexafluoride (SF6) core, was investigated for use in SHAPE. The study uses excitations of 25–700 kPa peak negative pressure (PNP) and 3 MHz frequency over eight pressurization cycles between atmospheric pressure and overpressures, ranging from 0 to 25 kPa (0 to 186 mm Hg). The SonoVue subharmonic response was characterized into two types. Unlike other microbubbles, SonoVue showed significant subharmonic signals at low excitations (PNPs, 25–400 kPa), denoted here as type I subharmonic. It linearly decreased with increasing overpressure (–0.52 dB/kPa at 100 kPa PNP). However, over multiple pressurization-depressurization cycles, type I subharmonic changed; its value at atmospheric pressure decreased over multiple cycles, and at later cycles, it recorded an increase in amplitude with overpressure (highest, +13 dB at 50 kPa PNP and 10 kPa overpressure). The subharmonic at higher excitations (PNP > 400 kPa), denoted here as type II subharmonic, showed a consistent decrease with the ambient pressure increase with strongest sensitivity of –0.4 dB/kPa at 500 kPa PNP. [ABSTRACT FROM AUTHOR]

Buildings with large open spaces in which chemicals are handled are often exposed to the risk of explosions. Computational fluid dynamics is a useful and convenient way to investigate contaminant dispersion in such large spaces. The turbulent Schmidt number (Sct) concept has typically been used in this regard, and most studies have adopted a default value. We studied the concentration distribution for sulfur hexafluoride (SF6) assuming different emission rates and considering the effect of Sct. Then we examined the same problem for a light gas by assuming hydrogen gas (H2) as the contaminant. When SF6 was considered as the contaminant gas, a variation in the emission rate completely changed the concentration distribution. When the emission rate was low, the gravitational effect did not take place. For both low and high emission rates, an increase in Sct accelerated the transport rate of SF6. In contrast, for H2 as the contaminant gas, a larger Sct could induce a decrease in the H2 transport rate. [ABSTRACT FROM AUTHOR]

Observational monitoring of the stratospheric transport circulation, the Brewer–Dobson circulation (BDC), is crucial to estimate any decadal to long-term changes therein, a prerequisite to interpret trends in stratospheric composition and to constrain the consequential impacts on climate. The transport time along the BDC (i.e. the mean stratospheric age of air, AoA) can best be deduced from trace gas measurements of tracers which increase linearly with time and are chemically passive. The gas sulfur hexafluoride (SF 6) is often used to deduce AoA because it has been increasing monotonically since the ∼ 1950s, and previously its chemical sinks in the mesosphere have been assumed to be negligible for AoA estimates. However, recent studies have shown that the chemical sinks of SF 6 are stronger than assumed and become increasingly relevant with rising SF 6 concentrations. To adjust biases in AoA that result from the chemical SF 6 sinks, we here propose a simple correction scheme for SF 6 -based AoA estimates accounting for the time-dependent effects of chemical sinks. The correction scheme is based on theoretical considerations with idealized assumptions, resulting in a relation between ideal AoA and apparent AoA which is a function of the tropospheric reference time series of SF 6 and of the AoA-dependent effective lifetime of SF 6. The correction method is thoroughly tested within a self-consistent data set from a climate model that includes explicit calculation of chemical SF 6 sinks. It is shown within the model that the correction successfully reduces biases in SF 6 -based AoA to less than 5 % for mean ages below 5 years. Tests using only subsampled data for deriving the fit coefficients show that applying the correction scheme even with imperfect knowledge of the sink is far superior to not applying a sink correction. Furthermore, we show that based on currently available measurements, we are not able to constrain the fit parameters of the correction scheme based on observational data alone. However, the model-based correction curve lies within the observational uncertainty, and we thus recommend using the model-derived fit coefficients until more high-quality measurements are able to further constrain the correction scheme. The application of the correction scheme to AoA from satellites and in situ data suggests that it is highly beneficial to reconcile different observational estimates of mean AoA. [ABSTRACT FROM AUTHOR]

Context. Improving cattle feed efficiency would reduce feed costs and increase herd profitability. Residual feed intake (RFI) is commonly used to rank cattle for feed efficiency, with low-RFI animals being more efficient than high-RFI animals. However, RFI classification merits further investigation because observed differences in heat energy (HE) production between low- and high-RFI cattle may be related to heat associated with differences in dry-matter intake (DMI) rather than maintenanceenergy requirements. Aims. To determine energy partitioning of beef heifers with low and high residual feed intake. Methods. Angus crossbred heifers (n = 60) were fed a grower diet (metabolisable energy (ME) = 2.17 Mcal/kg DM) for 70 days. Feed intake was recorded daily using the GrowSafe system, and bodyweight (BW) was recorded every 14 days. Residual feed intake was calculated as the residual from the regression of DMI on mid-test BW0.75 and average daily gain (ADG) (R2 = 0.31). Low-RFI (n = 8) and high-RFI (n = 8) heifers were selected for a metabolism experiment to determine energy partitioning at three feed-intake levels, namely, ad libitum intake, and 1.0× and 0.5× expected maintenance-energy requirement. Apparent nutrient digestibility was determined using indigestible neutral detergent fibre (iNDF) as an internal marker. The sulfur hexafluoride (SF6) tracer and oxygen-pulse techniques determined methane emissions and heat production respectively. Metabolisable energy required for maintenance (MEm) and fasting heat production (HeE) were then calculated from the regression of log HP on ME intake (MEI). Efficiencies of ME used for maintenance and growth were calculated from HeE, MEm, and retained energy at ad libitum intake. Key results. Residual feed intake was strongly correlated with DMI (0.83). Low-RFI heifers consumed 31% less (P = 0.01) feed than high-RFI heifers during the performance experiment. Heifers with low RFI had greater MEm, but similar efficiencies of ME use for maintenance and gain as did high RFI heifers. Conclusion. These data indicated that selection based on RFI may not lead to improved energy efficiency in growing heifers. Implications. The results of this study indicated that low-RFI cattle may not have lower maintenance-energy requirements or differences in efficiencies of ME use than do high-RFI cattle. [ABSTRACT FROM AUTHOR]

Sulfur hexafluoride (SF6) is a potent greenhouse gas. Here we use long-term atmospheric observations to determine SF6 emissions from China between 2011 and 2021, which are used to evaluate the Chinese national SF6 emission inventory and to better understand the global SF6 budget. SF6 emissions in China substantially increased from 2.6 (2.3-2.7, 68% uncertainty) Gg yr−1 in 2011 to 5.1 (4.8-5.4) Gg yr−1 in 2021. The increase from China is larger than the global total emissions rise, implying that it has offset falling emissions from other countries. Emissions in the less-populated western regions of China, which have potentially not been well quantified in previous measurement-based estimates, contribute significantly to the national SF6 emissions, likely due to substantial power generation and transmission in that area. The CO2-eq emissions of SF6 in China in 2021 were 125 (117-132) million tonnes (Mt), comparable to the national total CO2 emissions of several countries such as the Netherlands or Nigeria. The increasing SF6 emissions offset some of the CO2 reductions achieved through transitioning to renewable energy in the power industry, and might hinder progress towards achieving China's goal of carbon neutrality by 2060 if no concrete control measures are implemented. Atmospheric measurements show that China's emissions of the potent greenhouse gas, sulfur hexafluoride, grew rapidly between 2011 and 2021. This rise could offset some of China's progress towards its greenhouse gas emission reduction goal. [ABSTRACT FROM AUTHOR]