Search Results (59)

Deep coalbed methane (CBM) reservoirs are characterized by high hydrocarbon content and are considered an important strategic resource. Due to their inherently low permeability and porosity, horizontal well drilling is commonly employed to enhance production, with the length of the horizontal section playing a critical role in determining CBM output. However, during extended horizontal drilling, wellbore instability frequently occurs as a result of drilling fluid invasion into the coal formation, posing significant safety challenges. This instability is primarily caused by the physical intrusion of drilling fluids and their interactions with the coal seam, which alter the mechanical integrity of the formation. To address these challenges, interpenetrating and semi-interpenetrating network (IPN/s-IPN) hydrogels have gained attention due to their superior physicochemical properties. This material offers enhanced sealing and support performance across fracture widths ranging from micrometers to millimeters, making it especially suited for plugging applications in deep CBM reservoirs. A self-degradable interpenetrating double-network hydrogel particle plugging agent (SSG) was developed in this study, using polyacrylamide (PAM) as the primary network and an ionic polymer as the secondary network. The SSG demonstrated excellent thermal stability, remaining intact for at least 40 h in simulated formation water at 120 °C with a degradation rate as high as 90.8%, thereby minimizing potential damage to the reservoir. After thermal aging at 120 °C, the SSG maintained strong plugging performance and favorable viscoelastic properties. A drilling fluid containing 2% SSG achieved an invasion depth of only 2.85 cm in an 80–100 mesh sand bed. The linear viscoelastic region (LVR) ranged from 0.1% to 0.98%, and the elastic modulus reached 2100 Pa, indicating robust mechanical support and deformation resistance. Full article

Dredging of fine sediments and dumping of fines at disposal sites produce passive plumes behind the dredging equipment. Each type of dredging method has its own plume characteristics. All types of dredging operations create some form of turbidity (spillage of dredged materials) in the water column, depending on (i) the applied method (mechanical grab/backhoe, hydraulic suction dredging with/without overflow), (ii) the nature of the sediment bed, and (iii) the hydrodynamic conditions. A simple parameter to represent the spillage of dredged materials is the spill percentage (R_spill) of the initial load. In the case of cutter dredging and hopper dredging without overflow, sediment spillage is mostly low, with values in the range of 1% to 3%, The spill percentage is higher, in the range of 3% to 30%, for hopper dredging of mud with intensive overflow. Spilling of dredged materials also occurs at disposal sites. The spill percentage is generally low, with values in the range of 1% to 3%, if the load is dumped through bottom doors in deep water, creating a dynamic plume which descends rapidly to the bottom with cloud velocities of 1 m/s. The most accurate approach to study passive plume behavior is the application of a 3D model, which, however, is a major, time-consuming effort. A practical 1D plume dispersion model can help to identify the best parameter settings involved and to conduct fast scan studies. The proposed 1D model represents equations for dynamic plume behavior, as well as passive plume behavior including advection, diffusion and settling processes. Full article

The overall goal of this study is to synthesize the existing literature on mix design approaches and to develop recommendations for the best practices for the design of asphalt mixtures specific to LVRs. The synthesis of best practices encompasses material characterization, performance evaluation techniques, and recommendations for construction and maintenance practices. This review suggests the need for further laboratory and field testing to enhance performance measures, explore sustainable materials and construction practices, and develop standardized specifications for the diverse needs of low-volume road networks. The recommended changes (or guidelines) include, but are not limited to, updated recycled asphalt pavement (RAP) percentages as per current law requirements, the addition of performance tests (IDEAL-CT and IDEAL-RT), RAP content, design methodology, volumetrics, and design gyrations. The review suggests the need for further laboratory and field testing, including performance testing, long-term performance assessments in various conditions, and improved methodologies for evaluating testing parameters. These enhancements aim to ensure more reliable performance predictions and the better implementation of LVR technologies. Overall, this study will help agencies and the paving industry to understand the updates made to the current LVR specifications and evaluate the mix design considerations for low-volume roads. Full article

Background: Emphysema is a chronic lung disease characterized by alveolar wall destruction, leading to impaired gas exchange. Giant bullous emphysema (GBE) is a severe form of emphysema, often requiring surgical intervention. Video-assisted thoracoscopic surgery (VATS) is a minimally invasive approach for various thoracic pathologies, including lung volume reduction surgery (LVRS) and bullectomy for emphysematous bullae. Uniportal VATS (U–VATS), a further refinement, offers benefits such as reduced postoperative pain and faster recovery. Methods: This retrospective study analyzed data from two high-volume European Thoracic Surgery centers between August 2016 to January 2024. A total of 29 patients underwent U–VATS bullectomy for GBE. Results: Nineteen patients were males (65.5%) with a mean age of 44.7 ± 8.8 years. Ten (34.5%) were active smokers. Eighteen patients (62.1%) presented with a single giant bulla, while the remaining cases were in the context of pulmonary emphysema. Four patients (13.8%) presented with pneumothorax, with one requiring preoperative chest drainage. Twenty-eight patients (96.6%) underwent only U–VATS bullectomy, with additional chemical pleurodesis in eleven cases (37.9%). One patient (3.4%) underwent a left upper lobectomy for a giant bulla and NSCLC. In cases of severe lung emphysema and fragile pulmonary tissue, the stapler line was buttressed with Gore^® Seamguard^®. No conversions to thoracotomy, postoperative air-leaks, or major complications were recorded. At a mean follow-up time of 22.0 ± 14.0 months, no pneumothorax recurrence was documented. At about six months after surgery, pulmonary function significantly improved. Conclusions: U–VATS bullectomy appears to be a safe and feasible technique for the treatment of bullae in GBE, offering promising postoperative outcomes. Full article

With the development of piezoelectric-on-insulator (POI) substrates, X-cut LiNbO₃ thin-film resonators with interdigital transducers are widely investigated due to their adjustable resonant frequency (f_s) and effective electromechanical coupling coefficient ($K_{eff}^2$). This paper presents an in-depth study of simulations and measurements of laterally excited bulk acoustic wave resonators based on an X-cut LiNbO₃/SiO₂/Si substrate and a LiNbO₃ thin film to analyze the effects of electrode angle rotation ($\theta$) on the modes, f_s, and $K_{eff}^2$. The rotated $\theta$ leads to different electric field directions, causing mode changes, where the resonators without cavities are longitudinal leaky SAWs (LLSAWs, $\theta$ = 0$°$) and zero-order shear horizontal SAWs (SH₀-SAWs, $\theta$ = 90$°$) and the resonators with cavities are zero-order-symmetry (S₀) lateral vibrating resonators (LVRs, $\theta$ = 0$°$) and SH₀ plate wave resonators (PAW, $\theta$ = 90$°$). The resonators are fabricated based on a 400 nm X-cut LiNbO₃ thin-film substrate, and the measured results are consistent with those from the simulation. The fabricated LLSAW and SH₀-SAW without cavities show a $K_{eff}^2$ of 1.62% and 26.6% and a Bode-Q_max of 1309 and 228, respectively. Meanwhile, an S₀ LVR and an SH₀-PAW with cavities present a $K_{eff}^2$ of 4.82% and 27.66% and a Bode-Q_max of 3289 and 289, respectively. In addition, the TCF with a different rotated $\theta$ is also measured and analyzed. This paper systematically analyzes resonators on X-cut LiNbO₃ thin-film substrates and provides potential strategies for multi-band and multi-bandwidth filters. Full article

Introduction: Mitral annular plane systolic excursion (MAPSE) is a quantitative feature of left ventricular (LV) function that can be easily measured by M-mode echocardiography. The more recent LV strains represent LV contractility, and they can be determined for the three main directions in the radial (RS), longitudinal (LS), and circumferential (CS) directions. Three-dimensional (3D) speckle-tracking echocardiography (3DSTE) seems to be ideal for the simultaneous assessment of all LV strains from the same acquired 3D dataset. Their associations, however, have not been fully analyzed in clinical settings in healthy volunteers yet. Therefore, the present study aimed to find associations between MAPSE and 3DSTE-derived LV strains in healthy circumstances. Methods: The present study consisted of 106 healthy adult volunteers (mean age 28.1 ± 6.3 years, 48 men). Complete two-dimensional Doppler echocardiography with MAPSE assessment and 3DSTE-derived LV strain measurements were performed in all cases. Results: Tendentiously reduced LV volumes with preserved LV ejection fraction were present in the case of mean MAPSE as compared to decreased/increased MAPSE. Global and regional LV-RS and LV-CS did not differ if MAPSE was increased, mean or decreased. Global LV-LS was reduced in the case of decreased MAPSE, mainly due to tendentiously higher apical LV-LS. MAPSE did not differ if global LV-RS and LV-CS were increased, mean or decreased. MAPSE was tendentiously increased in the presence of increased global LV-LS. Conclusions: Only 3DSTE-derived global LV-LS and MAPSE are associated in healthy adults; LV global strains in other directions show no relationship with MAPSE. Full article

Introduction. Volumetric changes in the left atrium (LA) and left ventricle (LV) are strongly associated in healthy circumstances, as recent three-dimensional speckle-tracking echocardiographic (3DSTE) studies confirmed. However, the complex relationship of LA and LV deformation in systole has never been assessed in healthy individuals. The present study purposed to perform comparative simultaneous analysis of systolic LA and LV strains in healthy adults by 3DSTE. Methods. The study consisted of 165 healthy adults (mean age: 33.2 ± 12.3 years; 90 males). Complete two-dimensional Doppler echocardiography with 3DSTE was performed in all cases. Results. The increase in global LA radial strain (RS) and longitudinal strain (LS) showed no associations with LV strains. The largest global LA circumferential strain (CS) was associated with the largest basal LV-RS. Lowest basal and global LV-CS could be demonstrated in the presence of mean global LA-CS as compared to the presence of lower than mean global LA-CS. Global LA-RS showed an increase, with global LV-RS being largest when global LV-RS was the largest. Basal and global LA-RS were largest in the case of lowest global LV-CS. Basal LA-LS was largest in the case of mean global LV-CS. With the increase in global LV-LS, basal and global LA-LS showed an increase but only up to a point; in the case of larger than mean global LV-LS, no further increase was detected in basal and global LA-LS. Conclusions. Complex associations between simultaneously assessed LA and LV deformations represented by 3DSTE-derived strains could be demonstrated in healthy adults. Full article

Scour near various offshore structures (monopile, caisson foundation and jacket structure) was studied by performing laboratory flume tests and numerical solutions with a semi-empirical model (SEDSCOUR) and a sophisticated 2DV model (SUSTIM2DV). The laboratory test results show that the maximum free scour depth around a monopile without bed protection is slightly higher than the pile diameter. The maximum scour consisting of pile scour and global scour around an open jacket structure standing on four piles is much lower than the scour near the other structures (monopile and caisson). The maximum scour depth along a circular caisson foundation is found to be related to the base diameter of the structure. The main cause of the scour near these types of structures is the increase in the velocity along the flanks of the structure. Six cases have been used for validation: two laboratory cases (A and B) and four field cases (C, D, E and F). The measured scour values of the new physical model tests with the monopile and the open jacket structure presented in this paper are in reasonably good agreement with other laboratory and field scour data from the literature. The semi-empirical SEDSCOUR model proposed in this paper can be used for the reliable prediction of free scour and global scour near monopiles and jacket structures in a sandy bed (even with a small percentage of mud, up to 30%). The maximum scour depth along a large-scale caisson structure is more difficult to predict because the scour depth depends on the precise geometry and dimensions of the structure and the prevailing flow and sediment conditions. A detailed 2DV model with a fine horizontal grid (2 m) along a stream tube following the contour of the caisson is explored for scour predictions. The 2DV model simulates the flow and sediment transport at 50 to 100 points over the depth along the stream tube and can be run on a time-scale of 1 year. Full article

Background: Despite evidence that low vision rehabilitation (LVR) services can improve visual function in patients with neovascular age-related macular degeneration (nAMD), many patients are not directed to access these resources. This study was conducted to determine factors associated with LVR referral and to assess the visual outcomes from completed evaluations. Methods: The study comprised a retrospective, cross-sectional analysis of patients with nAMD. Referrals for LVR services were extracted from the electronic health record (EHR). The effectiveness of each evaluation was determined by assessing the change in best corrected visual acuity (BCVA) achieved after distance refraction. Costs, quality-adjusted life years (QALYs), and incremental costs per-QALY-gained were calculated based upon the better-seeing eye by using a willingness-to-pay threshold of $50,000/QALY. Results: Out of 560 eligible patients with nAMD, 110 were referred for LVR (19.6%). Referral was more common for individuals who qualified as having low vision, based upon the visual acuity of the better-seeing eye (adjusted odds ratio [aOR], 3.214; 95% confidence interval [CI], 1.920–5.380, p < 0.001), had bilateral nAMD (aOR, 1.592; 95% CI, 1.017–2.492, p = 0.042), or had commercial health insurance compared to those who had Medicare (aOR, 2.887; 95% CI, 1.041–8.009, p = 0.042). Most patients referred completed LVR appointments (86%). More than half of the patients achieved improved BCVA for their better-seeing eye (53%) yielding an average gain of 0.04 QALYs/patient at a cost of $3504/QALY. The estimated net monetary benefit was $1704 per evaluation completed. Conclusions: Most patients with nAMD achieved improvements in visual function after low vision evaluation, yielding improvements in vision-related quality of life at a reasonable cost. Full article

In this study, 3-trimethoxy-silylpropane-1-thiol (MPTMS) was used as a surface modifier for Al₂O₃ powder to systematically analyze the effects of MPTMS concentration on the rheological properties, photocuring characteristics, and 3D printing performance of photocurable composite slurries. MPTMS concentration significantly influenced the rheological behavior of the slurry. Slurries containing 2 wt.% and 5 wt.% MPTMS exhibited a wide linear viscoelastic range (LVR). However, at concentrations of 10 wt.% and 20 wt.%, the LVR range narrowed, which led to reduced dispersion stability. In dispersion stability tests, the slurry with 2 wt.% MPTMS showed the most stable dispersion, while the 5 wt.% MPTMS concentration exhibited the highest photocuring rate. In 3D printing experiments, the 5 wt.% MPTMS concentration resulted in the most stable printed structures, whereas printing failures occurred with the 2 wt.% concentration. At 10 wt.% and 20 wt.%, internal cracking was observed, leading to structural defects. In conclusion, MPTMS forms silane bonds on the Al₂O₃ surface, significantly impacting the stability, rheological properties, and printing quality of Al₂O₃-acrylate composite slurries. An MPTMS concentration of 5 wt.% was found to be optimal, contributing to the formation of stable and robust structures. Full article

Introduction: The right ventricle (RV) lies on the left ventricle (LV), and their shapes and movements are characteristic and significantly different. The aim of the present study was to investigate the relationship between three-dimensional speckle-tracking echocardiography (3DSTE)-derived LV strains, which represent LV contractility as quantitative features, and tricuspid annular plane systolic excursion (TAPSE) as determined by M-mode echocardiography, which represents the longitudinal movement of the RV, in healthy adults. Methods: A total of 79 healthy adults (mean age: 28.1 ± 6.3 years; 33 men) were enrolled in the present study. After two-dimensional Doppler echocardiography, 3DSTE-derived data acquisition was carried out in all cases, and detailed 3DSTE-based analysis was performed offline at a later date. Results: Reduced TAPSE was associated with increased global and basal LV radial strain (RS). Increased TAPSE was also associated not only with increased global and basal LV-RS but also with global LV longitudinal strain (LS). An increase in global LV-RS and global LV circumferential strain (CS) showed associations with other strains except for global LV-LS. An increase in global LV-LS did not show associations with other strains. Increased global LV-RS was associated with reduced TAPSE, while the degree of global LV-LS and global LV-CS did not show associations with TAPSE. Conclusions: Three-dimensional speckle-tracking echocardiography-derived LV-RS and LV-LS are associated with the longitudinal shortening of the RV represented by TAPSE in healthy adults. Full article

Emphysema in patients with chronic obstructive pulmonary disease (COPD) is characterized by progressive inflammation. Preclinical studies suggest that lung volume reduction surgery (LVRS) and mesenchymal stromal cell (MSC) treatment dampen inflammation. We investigated the effects of bone marrow-derived MSC (BM-MSC) and LVRS on circulating and pulmonary immune cell profiles in emphysema patients using mass cytometry. Blood and resected lung tissue were collected at the first LVRS (L1). Following 6–10 weeks of recovery, patients received a placebo or intravenous administration of 2 × 10⁶ cells/kg bodyweight BM-MSC (n = 5 and n = 9, resp.) in week 3 and 4 before the second LVRS (L2), where blood and lung tissue were collected. Irrespective of BM-MSC or placebo treatment, proportions of circulating lymphocytes including central memory CD4 regulatory, effector memory CD8 and γδ T cells were higher, whereas myeloid cell percentages were lower in L2 compared to L1. In resected lung tissue, proportions of Treg (p = 0.0067) and anti-inflammatory CD163⁻ macrophages (p = 0.0001) were increased in L2 compared to L1, while proportions of pro-inflammatory CD163⁺ macrophages were decreased (p = 0.0004). There were no effects of BM-MSC treatment on immune profiles in emphysema patients. However, we observed alterations in the circulating and pulmonary immune cells upon LVRS, suggesting the induction of anti-inflammatory responses potentially needed for repair processes. Full article

LVR-15 is a light-water-tank-type research reactor placed in a stainless-steel vessel under a shielding cover located in the Research Centre Rez (CVR) near Prague. It is operated at a steady-state power of up to 10 MWt under atmospheric pressure and is cooled by forced circulation. In 2011, the fuel was replaced, going from high-enriched uranium (HEU) to low-enriched uranium (LEU). After 2017, the State Office for Nuclear Safety (SUJB) asked CVR to evaluate the LVR-15 under Design Extended Conditions B (DEC-B). For this reason, a new model was developed in the MELCOR code, which allows for modelling the progression of a severe accident (SA) in light-water nuclear power plants and estimating the behaviour of the reactor under SA conditions. The model was built by collecting information about the LVR-15. Since the research reactor can have different core configurations according to the location of the core components, the core configuration with the most fuel (hottest campaign K221) was selected. Then, to create the radial nodalisation, the details of the core components were obtained and grouped in five radial rings and 27 axial levels. The simulation was run with the boundary conditions collected from campaign K221, and the results were compared with the reference values of the campaign with a negligible percentage of error. For the coolant inlet and outlet temperature, the reference values were 318.18 K and 323.5 K, respectively, while for the simulation, the steady state reached 319 K for the inlet temperature and 324 K for the outlet temperature. Additionally, the cladding temperature of the hottest assembly was compared with the reference value (353.72 K) and the steady-state simulation results (362 K). In future work, different transients leading to severe accidents will be simulated. When simulating the LVR-15 reactor with MELCOR, specific attention is required for the aluminium-cladded fuel assemblies, as the model requires some assumptions to cope with the phenomenological limitations. Full article

The increasing adoption of battery storage units alongside private PV systems may prove to be a new challenge for distribution grid operators. This study explored the potential impact of marketing aggregated battery discharge power as a Fast Frequency Reserve (FFR) and its effect on the distribution grid stability. We investigated the efficacy of Line Voltage Regulators (LVRs) in mitigating voltage surges caused by simultaneous battery activation. For this purpose, a simulation was developed via Matlab (Version R2023a) to simulate the voltage at the nodes of an arbitrary distribution grid, using the feed-in and consumed power of the customers as the input. We applied the model to a distribution grid section in Sundsvall (Sweden). The results confirmed that LVRs can amplify voltage surges when their adjustments are not synchronized with the FFR activation. This study underscored the need for proactive measures to address the voltage maintenance challenges arising from the integration of battery storage units and renewable energy sources. Full article

The Nile River Basin (NRB) has experienced a notable rise in drought episodes in recent decades. The propagation of meteorological, agricultural, and groundwater drought dynamics in the NRB was investigated in this study. The following drought indices examined the correlation and propagation among meteorological, agricultural, and groundwater droughts. These are the standardized precipitation evapotranspiration index (SPEI), soil moisture index, Gravity Recovery and Climate Experiment, and GRACE Follow-On (GRACE/GRACE-FO)-derived groundwater drought index (GGDI). These droughts were comprehensively evaluated in the NRB from 2003 to 2022. The cross-wavelet transform approach highlighted the links between droughts. The following are the key findings: (1) In the NRB, the cross-wavelet energy spectrum of wavelet coherence can indicate the internal connection between meteorological versus (vs.) agricultural and agricultural versus (vs.) groundwater drought. The time scale with the most significant correlation coefficient is the drought propagation time. (2) The El Niño–Southern Oscillation (ENSO) correlated with agricultural and groundwater drought much more than the Indian Ocean Dipole (IOD), demonstrating that ENSO has an important impact on drought advancement. (3) The R² values were 0.68 for GGDI vs. standardized soil moisture index (SSI), 0.71 for Blue Nile Region (BNR) GGDI vs. SSI, and 0.55 for SSI vs. Standardized Precipitation Evapotranspiration Index (SPEI). Similarly, in the Lake Victoria Region (LVR), GGDI vs. SSI was 0.51 and SSI vs. SPEI was 0.55, but in the Bahr-el-Ghazal Region (BER), GGDI vs. SSI was 0.61 and SSI vs. SPEI was 0.27 during the whole research period with varied lag durations ranging from 1 to 6 months. Thus, the propagation of drought (i.e., meteorological, agricultural, and groundwater drought) dynamics has the potential to reshape our understanding of drought evolution, which could lead to early drought forecasting across the NRB and similar climatic regions. Full article