Search

Internal solitary waves (ISWs) contain great energy and have the characteristics of emergency and concealment. To avoid their damage to offshore engineering, a new generation of monitoring and early warning system for ISWs was developed using technologies of double buoys monitoring, intelligent real-time data transmission, and automatic software identification. The system was applied to the second natural gas hydrates (NGHs) production test in the Shenhu Area, South China Sea (SCS) and successfully provided the early warning of ISWs for 173 days (from October 2019 to April 2020). The abrupt changes in the thrust force of the drilling platform under the attack of ISWs were consistent with the early warning information, proving the reliability of this system. A total of 93 ISWs were detected around the drilling platform. Most of them occurred during the spring tides in October–December 2019 and April 2020, while few of them occurred in winter. As suggested by the theoretical model, the full-depth structure of ISWs was a typical current profile of mode-1, and the velocities of wave-induced currents can reach 80 cm/s and 30 cm/s, respectively, in the upper ocean and near the seabed. The ISWs may be primarily generated from the interactions between the topography and semidiurnal tides in the Luzon Strait, and then propagate westward to the drilling platform. This study could serve as an important reference for the early warning of ISWs for offshore engineering construction in the future.

Natural gas hydrates (NGHs) are a new type of clean energy with great development potential. However, it is urgent to achieve safe and economical NGHs development and utilization. This study established a physical model of the study area using the FLAC3Dsoftware based on the key parameters of the NGHs production test area in the South China Sea, including the depressurization method, and mechanical parameters of strata, NGHs occurrence characteristics, and the technological characteristics of horizontal wells. Moreover, this study explored the law of influences of the NGHs dissociation range on the stability of the overburden strata and the casing structure of a horizontal well. The results are as follows. With the dissociation of NGHs, the overburden strata of the NGHs dissociation zone subsided and formed funnel-shaped zones and then gradually stabilized. However, the upper interface of the NGHs dissociation zone showed significant redistribution and discontinuity of stress. Specifically, distinct stress concentration and corresponding large deformation occurred in the build-up section of the horizontal well, which was thus prone to suffering shear failure. Moreover, apparent end effects occurred at the end of the horizontal well section and might cause the deformation and failure of the casing structure. Therefore, it is necessary to take measures in the build-up section and at the end of the horizontal section of the horizontal well to prevent damage and ensure the wellbore safety in the long-term NGHs exploitation.

Clayey silt reservoirs bearing natural gas hydrates (NGH) are considered to be the hydrate-bearing reservoirs that boast the highest reserves but tend to be the most difficult to exploit. They are proved to be exploitable by the first NGH production test conducted in the South China Sea in 2017. Based on the understanding of the first production test, the China Geological Survey determined the optimal target NGH reservoirs for production test and conducted a detailed assessment, numerical and experimental simulation, and onshore testing of the reservoirs. After that, it conducted the second offshore NGH production test in 1225 m deep Shenhu Area, South China Sea (also referred to as the second production test) from October 2019 to April 2020. During the second production test, a series of technical challenges of drilling horizontal wells in shallow soft strata in deep sea were met, including wellhead stability, directional drilling of a horizontal well, reservoir stimulation and sand control, and accurate depressurization. As a result, 30 days of continuous gas production was achieved, with a cumulative gas production of 86.14 ×104m3. Thus, the average daily gas production is 2.87 ×104m3, which is 5.57 times as much as that obtained in the first production test. Therefore, both the cumulative gas production and the daily gas production were highly improved compared to the first production test. As indicated by the monitoring results of the second production test, there was no anomaly in methane content in the seafloor, seawater, and atmosphere throughout the whole production test. This successful production test further indicates that safe and effective NGH exploitation is feasible in clayey silt NGH reservoirs. The industrialization of hydrates consists of five stages in general, namely theoretical research and simulation experiments, exploratory production test, experimental production test, productive production test, and commercial production. The second production test serves as an important step from the exploratory production test to experimental production test.

Children presenting with partial physeal arrest and significant remaining growth may benefit from physeal bar resection, although the operation is a technique demanding procedure. This study evaluates the treatment of post-traumatic pediatric ankle varus deformity using physeal bar resection and hemi-epiphysiodesis with the assistance of two operative methods. Forty-five patients presenting with a distal tibial medial physeal bridge as well as ankle varus deformity following traumatic ankle physeal injury between 2009 and 2017 were followed. These patients were treated with physeal bar resection and hemi-epiphysiodesis, with the assistance of either fluoroscopy (10 cases) or intraoperative three-dimensional navigation (35 cases). Of the 45 cases, the median age was 9.0 years (range: 3–14 years) with 28 male and 17 female patients. The median of pre-operation ankle varus angle was 20 degrees (IQR 15–25) and 5 degrees (IQR 0–20) at the time of final follow up, representing a statistically significant difference (P<0.05). No differences were observed with regards to age, gender, and surgical history between effective group and ineffective group (P>0.05). The median of pre-operative ankle varus angles of the navigation and fluoroscopy groups were both 20 degrees (P>0.05). The median correction angle of the navigation and fluoroscopy groups was 10 and 15 degrees, respectively (P>0.05). Our results indicate that physeal bar resection and hemiepiphysiodesis are effective treatments for correcting ankle varus deformity due to traumatic medial physeal arrest of the distal tibia. We observe no difference in outcome between fluoroscopy group and three-dimensional navigation group during the procedures.

Natural gas hydrate (NGH) is considered as one of the new clean energy sources of the 21st century with the highest potential. The environmental issues of NGH production have attracted the close attention of scientists in various countries. From May 10 to July 9, 2017, the first offshore NGH production test in the South China Sea (SCS) was conducted by the China Geological Survey. In addition, environmental security has also been effectively guaranteed via a comprehensive environmental monitoring system built during the NGH production test. The monitoring system considered sea-surface atmosphere methane and carbon dioxide concentrations, dissolved methane in the sea water column, and the seafloor physical oceanography and marine chemistry environment. The whole process was monitored via multiple means, in multiple layers, in all domains, and in real time. After the production test, an environmental investigation was promptly conducted to evaluate the environmental impact of the NGH production test. The monitoring results showed that the dissolved methane concentration in seawater and the near-seabed environment characteristics after the test were consistent with the background values, indicating that the NGH production test did not cause environmental problems such as methane leakage.

Reducing inflammation is a promising therapeutic approach for sepsis-induced cardiomyopathy (SIC). The 5-Methoxytryptophan (5-MTP) is a tryptophan metabolite that demonstrates anti-inflammatory, anti-fibrosis, anti-tumorigenesis, and anti-senescence features. Current investigations aimed to assess the 5-MTP pretreatment impacts on lipopolysaccharide (LPS)-induced cardiac injury and dysfunction. For in vivo studies, the mice were categorized randomly into four groups: control, LPS, LPS+5-MTP (25 mg/kg) and LPS+5-MTP (50 mg/kg). The mice in the LPS+5-MTP groups were given 5-MTP intraperitoneally once a day for 7 days. LPS (10 mg/kg) was then administered intraperitoneally for 24 h. Echocardiography, cardiac injury biomarkers, and H & E staining evaluated heart anatomy and function. The findings indicate that 5-MTP pretreatment significantly reduced LPS-induced heart dysfunction and morphological alterations. Western blot assay was used for investigating molecular mechanisms. After LPS stimulation, the pro-inflammatory cytokines (IL-1β, IL-6, TNF-α and NLRP3) protein levels increased while anti-inflammatory cytokine (IL-10) decreased; however, 5-MTP pretreatment mitigated this response by suppressing the stimulation of the NF-κB signaling pathway. Furthermore, 5-MTP administration reduced LPS-induced cardiac apoptosis, as demonstrated by increased protein levels of cleaved-Casepase-1, cleaved-Casepase-3 and Bax, and decreased protein level of Bcl-2 after LPS stimulation, whereas LPS-induced cardiac apoptosis was reversed by 5-MTP pretreatment. In vitro, 5-MTP pretreatment had a similar cardioprotective effect on cultured cardiac fibroblasts challenged with LPS. In conclusion, 5-MTP pretreatment can reduce LPS-induced cardiac inflammation and apoptosis, implying that 5-MTP is a possible therapeutic option for SIC.

The optimum antihypertensive treatment for prevention of hypertensive stroke has yet to be elucidated. This study was undertaken to examine the benefit of a combination of valsartan, an angiotensin II type 1 (AT1) receptor blocker, and amlodipine, a calcium channel blocker, in prevention of high-salt-induced brain injury in hypertensive rats. High-salt-loaded stroke-prone spontaneously hypertensive rats (SHRSPs) were given 1) vehicle, 2) valsartan (2 mg/kg/day), 3) amlodipine (2 mg/kg/day), or 4) a combination of valsartan and amlodipine for 4 weeks. The effects on brain injury were compared between all groups. High-salt loading in SHRSPs caused the reduction of cerebral blood flow (CBF), cerebral hypoxia, white matter lesions, glial activation, AT1 receptor up-regulation, endothelial nitric-oxide synthase (eNOS) uncoupling, inducible nitric-oxide synthase induction, and nitroxidative stress. Valsartan, independently of blood pressure, enhanced the protective effects of amlodipine against brain injury, white matter lesions, and glial activation in salt-loaded SHRSPs. These beneficial effects of valsartan added to amlodipine were associated with an additive improvement in CBF and brain hypoxia because of an additive improvement in cerebral arteriolar remodeling and vascular endothelial dysfunction. Furthermore, valsartan added to amlodipine enhanced the attenuation of cerebral nitroxidative stress through an additive suppression of eNOS uncoupling. Valsartan, independently of blood pressure, augmented the protective effects of amlodipine against brain injury in salt-loaded hypertensive rats through an improvement in brain circulation attributed to nitroxidative stress. Our results suggest that the combination of valsartan and amlodipine may be a promising strategy for the prevention of salt-related brain injury in hypertensive patients.

The present study was undertaken to examine the role of endothelial nitric oxide synthase (eNOS) in salt-sensitive renal injury.

High-salt diet is closely associated with the increase in cardiovascular events. However, the mechanism of high-salt-induced cardiovascular injury is unknown. The present study was undertaken to test our hypothesis that apoptosis signal-regulating kinase (ASK) 1 may be involved in salt-induced cardiovascular injury.

Type 2 diabetes plays a major role in the development of cardiovascular diseases. The present study was undertaken to investigate the effect of ezetimibe, a potent cholesterol absorption inhibitor, on cardiovascular injury of obese and type 2 diabetic db/db mice. Diabetic db/db mice fed a Western diet were given ezetimibe for 9 weeks, and the effects on cardiovascular injury and hepatic steatosis were examined. Ezetimibe treatment of db/db mice significantly improved vascular endothelial function, which was associated with the restoration of the decreased phospho-Akt and phospho-endothelial nitric-oxide synthase (eNOS). Moreover, ezetimibe also reduced vascular superoxide levels in db/db mice, accompanied by the attenuation of NADPH oxidase subunit gp91(phox) and Nox4 and the prevention of down-regulation of Cu/Zn-superoxide dismutase (SOD) and extracellular SOD. Thus, the improvement of vascular endothelial function by ezetimibe in diabetic mice seems to be attributed to the improvement of eNOS function and the attenuation of oxidative stress. Ezetimibe treatment also significantly attenuated cardiac interstitial fibrosis and coronary arterial thickening of diabetic mice and ameliorated cardiac macrophage infiltration. This improvement of cardiac injury was also related to the attenuation of NADPH oxidase-mediated oxidative stress. Furthermore, ezetimibe significantly prevented hepatic steatosis, inflammation, and oxidative stress in diabetic mice. Our work provides the first evidence that ezetimibe prevented cardiovascular injury and hepatic steatosis in diabetic mice. These beneficial effects were attributed to the attenuation of oxidative stress and inflammation and the improvement of eNOS function. Therefore, we propose that ezetimibe may be a promising therapeutic drug for obese and type 2 diabetes.

Addition of aliskiren, a direct renin inhibitor, to losartan provides additive reduction of urinary albumin excretion in type 2 diabetic patients. However, the detailed effect of aliskiren on type 2 diabetic nephropathy is still unknown. This study was undertaken to examine the efficacy of aliskiren and the combination of aliskiren with valsartan on type 2 diabetic nephropathy.

Benidipine is a dihydropyridine calcium channel blocker inhibiting not only L-type but also T-type calcium channels. To elucidate potential additive benefit of benidipine for prevention of cardiorenal injury, we compared the cardiac and renal protective effects of equihypotensive doses of benidipine and cilnidipine in stroke-prone spontaneously hypertensive rats (SHRSP).

The efficacy of renin–angiotensin system (RAS) blockers on type 2 diabetes and its complications remains to be defined. This study was undertaken to test the hypothesis that candesartan may enhance the protective effects of pioglitazone against type 2 diabetes.

The precise mechanism of salt-induced brain injury is unclear. We examined the detailed causative role of angiotensin II and NADPH oxidase in salt-accelerated brain injury of stroke-prone spontaneously hypertensive rats (SHRSP).

Very recent subgroup analysis from the PROspective pioglitAzone Clinical Trial In macroVascular Events has shown that pioglitazone reduces the risk of recurrent stroke in type 2 diabetic patients. However, the underlying mechanism of stroke prevention by pioglitazone is unknown. Our aim was to examine the effect of pioglitazone on hypertension-based stroke in rats.