Numerical investigation of mixed physical barriers for saltwater removal in coastal heterogeneous aquifers.

Saltwater intrusion is a prevalent global environmental issue that detrimentally impacts coastal groundwater aquifers. This problem is exacerbated by climate change and increased groundwater abstraction. Employing physical barriers proves effective in mitigating saline water intrusion. In this study, a validated numerical simulation model is utilized to assess the impact of aquifer stratification on the effectiveness of mixed physical barriers (MPBs) and their response to structural variations. Additionally, the performance of MPBs was compared with that of single physical barriers in a laboratory-scale aquifer. Three different configurations were replicated, comprising two stratified aquifers (HLH and LHL) and a homogenous reference aquifer (H). The results demonstrate that MPBs are efficient in decreasing the saltwater penetration length in the investigated cases. The reductions in penetration length were up to 65% in all cases. The removal efficacy of residual saline water for MPBs exceeded that of the subsurface dam by 2.1-3.3 times for H, 2.1-3.6 times for HLH, and 8.3 times for LHL conditions, while outperforming the cutoff wall by 38-100% for H, 39-44% for HLH, and 2.7-75% for LHL. These findings are of importance for decision-makers in choosing the most appropriate technique for mitigating saline water intrusion in heterogeneous coastal aquifers.

Satellite-based estimates of groundwater storage depletion over Egypt.

An arid climate accompanied by a freshwater shortage plagued Egypt. It has resorted to groundwater reserves to meet the increasing water demands. Fossil aquifers were lately adopted as the sole water source to provide the irrigation water requirements of the ongoing reclamation activities in barren areas. Yet, the scarcity of measurements regarding the changes in the aquifers' storage poses a great challenge to such sustainable resource management. In this context, the Gravity Recovery and Climate Experiment (GRACE) mission enables a novel consistent approach to deriving aquifers' storage changes. In this study, the GRACE monthly solutions during the period 2003-2021 were utilized to estimate alterations in terrestrial water storage (TWS) throughout Egypt. Changes in groundwater storage (GWS) were inferred by subtracting soil water content, derived from the GLDAS-NOAH hydrological model, from the retrieved TWS. The secular trends in TWS and GWS were obtained using the linear least square method, while the non-parametric technique (Mann-Kendall's tau) was applied to check the trend significance. The derived changes in GWS showed that all aquifers are undergoing a significant loss rate in their storage. The average depletion rate over the Sinai Peninsula was estimated at 0.64 ± 0.03 cm/year, while the depletion rate over the Nile delta aquifer was 0.32 ± 0.03 cm/year. During the investigated period (2003-2021), the extracted groundwater quantity from the Nubian aquifer in the Western Desert is estimated at nearly 7.25 km3. The storage loss from the Moghra aquifer has significantly increased from 32 Mm3/year (2003-2009) to 262 Mm3/year (2015-2021). This reflects the aquifer exposure for extensive water pumping to irrigate newly cultivated lands. The derived findings on the aquifers' storage losses provide a vital source of information for the decision-makers to be employed for short- and long-term groundwater management.

Subtle Myocardial Dysfunction and Fibrosis in Children with Rheumatic Heart Disease: Insight from 3D Echocardiography, 3D Speckle Tracking and Cardiac Magnetic Resonance Imaging.

Rheumatic heart disease (RHD) is a major cause of morbidity and mortality in developing countries, so early diagnosis and treatment can reduce morbidity and mortality resulting from subsequent valvular damage. The aim of this study was to detect subtle myocardial dysfunction among children with RHD with preserved left ventricular systolic function. This is a cross-sectional case-control study that was conducted on 30 children with RHD (who had valvular affection of any degree and were not in activity) compared to 23 healthy children. After history taking and cardiac examination, 2D echocardiography, tissue Doppler imaging, 3D-echocardiography and 3D speckle tracking echocardiography were done to both groups, whereas cardiac magnetic resonance imaging was done only to the patient group. The 3D-derived left ventricular end-diastolic volume and sphericity index among patients were significantly increased when compared to controls [131.5 (101.5 to 173.7) vs. 69 (58 to 92), P = 0.001, and 0.46 (0.36 to 0.59) vs. 0.33 (0.29 to 0.38), P = 0.001, respectively]. The 3D-derived ejection fraction and longitudinal strain did not differ significantly among both groups. The 3D-derived global circumferential strain was higher in patients when compared to controls [- 14 (- 16 to - 10) vs. - 11(- 13 to - 10), P = 0.04]. None of the examined patients demonstrated late enhancement myocardial fibrosis. In children with RHD and preserved systolic function, subtle systolic dysfunction could not be detected using conventional and novel non-conventional methods. This may indicate that the myocardial affection during the acute stage of rheumatic carditis is minimal with almost complete resolution.

Perimembranous Ventricular Septal Defect Device Closure: Choosing Between Amplatzer Duct Occluder I and II.

Transcatheter closure of perimembranous ventricular septal defects (pmVSDs) is a well-established procedure. Recently, Amplatzer duct occluders (ADO) I and II have been reported to close large series of pmVSDs successfully (off-label use). ADOs are economical compared with the standard Amplatzer VSD occluders, a major consideration in developing countries with low-budget programs. We report closure of symptomatic, hemodynamically significant pmVSDs using the ADOI and ADOII devices. Although there are no set criteria for choosing between ADOI and ADOII, the former's price tag includes snare and long sheath. Thus, we aim to predetermine device usage based on transthoracic echocardiography (TTE) findings. Between March 2013 and November 2014, 30 patients had transcatheter closure of pmVSDs using the ADO devices. The median age was 4 years (range 1.1-13 years) and median weight was 15 kg (range 6.5-85 kg). ADOII could not be used in VSDs larger than 6 mm and/or with a large aneurysm. The median VSD size as assessed by echocardiography was 5.5 mm while the mean was 5.5 mm (range 3-12 mm); while by angiography it was 5 mm & the mean was 4.75 mm (range 3-9 mm). The median fluoroscopy time (FT) was 8 min (range 5-38 min). We inserted ADOI in 13 patients and ADOII in 17 patients (no significant difference between median age and weight in each group). VSD size was significantly larger and FT was longer in ADOI patients; the device type matched what was decided from TTE data in 84% of cases. Follow-up ranged from 2 to 24 months (median 12 months). The mean LVEDD z-score of the patients was 1.1 before VSD closure, while it was 0.63, 0.35, and 0.23 at the 1-, 3 months, and last follow-up, respectively. Complete closure rates immediately, at 24 h, and at last follow-up were 87, 90, and 94% respectively. No patient developed heart block or any other complication. ADOI and ADOII are equally safe and effective in pmVSD closure. ADOII use, although cheaper than ADOI, is limited to smaller VSDs. The choice between ADOI and ADOII can be decided by TTE prior to procedure which is convenient in low economic programs.