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Dual-atom catalyst exhibits outstanding activity lies in the amount of site density, which is more than that of single-atom catalysts. It owns great potential in application of low-temperature Zn-air batteries.

Challenges remain to show good capacitive performance while achieving high loadings of active materials for supercapacitors. Trying to realize this version, a nickel-protecting carbon fiber paper@Co-doped NiSx(Ni-CP@Co–NiSx) electrode with high specific gravimetric, areal, and volumetric capacitance is reported in this work. This free-standing electrode is prepared by an electroplating-hydrothermal-electroplating (EHE) three-step method to achieve a high loading of almost 26.7 mg cm–2. The cobalt-doping and nickel-protection strategies effectively decrease the impedance and inhibit the active material dropping from the electrode resulting from the expansion stress, which endows the Ni-CP@Co–NiSxelectrode with a high rate and good cycling performance, especially with an ultrahigh specific areal/volumetric/gravimetric capacitance of 53.3 F cm–2/2807 F cm–3/1997 F g–1at 5 mA cm–2, respectively. Employing activated carbon functionalized with riboflavin (AC/VB2) as a negative electrode, the asymmetric supercapacitor device delivers a very high energy density of up to 60.4 W h kg–1. This work demonstrates that electrodes with a high loading density and excellent performance can be obtained by the combination of the EHE method to adjust the internal conductivity and external structural stability.

Highly stereoselective construction of 1,2-cis-Araplinkages has been achieved, which featured a broad range of alcoholic acceptors, including strong nucleophiles and complex bioactive molecules. This method was applied to a regioselective and orthogonal one-pot synthesis of a pentasaccharide, which was the structural motif of a side chain in type II arabinogalactan.

A mesoporous carbon spheres assisted-Ru nanoclusters/RuO2heterostructure catalyst modifies the adsorption energy of CO2and induces the redistribution of charge density, thus boosting CO2reduction significantly in a novel H2/CO2fuel cell.

This paper proves that on any tamed closed almost complex four-manifold (M, J) whose dimension of J-anti-invariant cohomology is equal to the self-dual second Betti number minus one, there exists a new symplectic form compatible with the given almost complex structure J. In particular, if the self-dual second Betti number is one, we give an affirmative answer to a question of Donaldson for tamed closed almost complex four-manifolds. Our approach is along the lines used by Buchdahl to give a unified proof of the Kodaira conjecture.

Described here is a selective synthesis of 2,3-dihydropyrrole-fused N-glycosides through rhodium-catalyzed denitrogenative transannulation of N-sulfonyl-1,2,3-triazoles with glycals. A series of pyrroline-fused N-glycosides are afforded in moderate to excellent yields with exclusive regioselectivity and stereoselectivity. Functional application of such a resultant product by oxidative addition and epoxidation is also explored. Notably, the treatment of a pyrroline-fused N-glycoside (3a) with TMSOTf efficiently leads to an interesting unexpected C-nucleoside (9) via a TMSOTf-inducing ring opening/acetyl migration/ring closing reaction sequence.

A H2/CO2fuel cell is a promising device that can convert CO2into hydrocarbon fuel with electricity generation. Herein, a facile electrospinning method has been used to synthesize the embedded Ru-CNF catalyst in which Ru nanoparticles are dispersed homogeneously within N-doped carbon nanofibers. This catalyst exhibits a high CH4production rate of 308.46 μmol gcat–1h–1at 170 °C, which is superior to that of the Ru/CNF (242.53 μmol gcat–1h–1) and Ru/CNT (194.24 μmol gcat–1h–1). The enhanced CO2RR performance of Ru-CNF is ascribed to the well-distributed Ru nanoparticles within the CNF matrix and synergistic effect of Ru sites with N species, which results in forming the increased CO2RR active sites, hence improving the catalytic activity. Simultaneously, it can achieve a peak power density of 1.8 W m–2on the strength of anodic (H2oxidation) and cathodic (CO2reduction and H2evolution) reactions with remarkable stability. Such findings give a theoretical basis of CO2RR in the H2/CO2fuel cell system, which could hold great value to further develop the high-efficiency catalysts for CO2reduction.

To reveal the dynamic mechanical characteristics of deep rocks, a series of impact tests under triaxial static stress states corresponding to depths of 300–2400 m were conducted. The results showed that both the strain rates and the stress environments in depth significantly affect the mechanical characteristics of rocks. The sensitivity of strain rate to the dynamic strength and deformation modulus shows a negative correlation with depth, indicating that producing penetrative cracks in deep environments is more difficult when damage occurs. The dynamic strength shows a tendency to decrease and then increase slightly, but decreases sharply finally. Transmissivity demonstrates a similar trend as that of strength, whereas reflectivity indicates the opposite trend. Furthermore, two critical depths with high dynamically induced hazard possibilities based on the China Jinping Underground Laboratory (CJPL) were proposed for deep engineering. The first critical depth is 600–900 m, beyond which the sensitivity of rock dynamic characteristics to the strain rate and restraint of circumferential stress decrease, causing instability of surrounding rocks under axial stress condition. The second one lies at 1500–1800 m, where the wave impedance and dynamic strength of deep surrounding rocks drop sharply, and the dissipation energy presents a negative value. It suggests that the dynamic instability of deep surrounding rocks can be divided into dynamic load dominant and dynamic load induced types, depending on the second critical depth.

Purpose: The purpose of this study is to assess the efficacy and safety of cilostazol prescription in patients with femoropopliteal peripheral artery disease (PAD) after endovascular therapy (EVT).Materials and methods: We conducted a systematic review and meta-analysis of all studies reporting the outcomes of cilostazol after femoropopliteal EVT of PAD up to September 2022. Clinical outcomes of interest included primary patency, in-stent restenosis (ISR), vessel re-occlusion, freedom from target lesion revascularization (TLR), repeat revascularization, all-cause mortality, amputation, major adverse cardiovascular events (MACEs) and major adverse limb events (MALEs), and bleeding complication.Results: A total of 4 randomized controlled trials (RCTs) and 8 observational studies containing a total of 4898 patients met the inclusion criteria and were included in this systematic review and meta-analysis. We found that the use of cilostazol was associated with higher primary patency after femoropopliteal artery EVT (odds ratio [OR]=1.67, 95% confidence interval [CI]=1.50-1.87, p<0.001, I2=33.2%), a lower risk of ISR (OR=0.43, 95% CI=0.29-0.63, p<0.001, I2=37.6%), repeat revascularization (OR=0.43, 95% CI=0.24-0.76, p<0.005, I2=27.4%), and vessel re-occlusion (OR=0.59, 95% CI=0.38-0.93, p<0.05, I2=0%). There was an increase in freedom from TLR rate (OR=2.19, 95% CI=1.58-3.05, p<0.001, I2=0%), as well as a reduction in the occurrence of MALEs (OR=0.50, 95% CI=0.29-0.85, p<0.05, I2=0%). However, there was no significant difference in amputation, MACEs, all-cause mortality, and major bleeding complications. Subgroup analysis showed that cilostazol treatment in patients with femoropopliteal drug-eluting stents (DES) implantation remained associated with higher primary patency and a lower risk of ISR.Conclusions: After EVT of femoropopliteal artery lesions, additional oral cilostazol enhances primary patency, reduces the occurrences of ISR and vessel re-occlusion, diminishes the risks associated with MALEs, lowers the need for repeat revascularization, and increases freedom from TLR rates. However, it does not impact amputation, MACEs, all-cause mortality, or major bleeding complications. These findings suggest cilostazol as a potentially safe and effective adjunct therapy in patients with femoropopliteal PAD after EVT.Clinical Impact After undergoing endovascular therapy (EVT) for femoropopliteal artery lesions, the addition of cilostazol to antiplatelet therapy can significantly improve primary patency, reducing the incidence of in-stent restenosis, repeat revascularization, vessel re-occlusion, and major adverse limb events while increasing freedom from target lesion revascularization rate. The simultaneous use of drug-eluting stents in the femoropopliteal artery lesions, combined with cilostazol, potentially results in a synergistic anti-stenotic effect. This therapeutic approach does not appear to be associated with an increased risk of major bleeding events or all-cause mortality. These findings provide additional evidence supporting the treatment of anti-stenosis in patients with femoropopliteal artery lesions after EVT.

Vapor-solid reaction methods are highly regarded as potential solutions for large-scale production of perovskite thin films due to their scalability, compatibility with silicon tandem technology, and lack of solvents. However, the limited penetration of organic vapor through the solid inorganic film results in a slow growth rate of perovskite, leading to poor crystallinity and small grain size. This high defect density in the grain boundaries hinders the enhancement of device performance. In this study, we used 1,3-diaminoguanidine monohydrochloride as an additive in the PbI2precursor films, which effectively improved perovskite grain growth in the vapor-solid reaction process. After optimization, we achieved high-quality perovskite thin films with a large grain size exceeding 5 μm. Notably, solar devices based on these large grain perovskite thin films achieved a high power conversion efficiency up to 21.13%.

The metal–nitrogen–carbon (M–N–C)-based catalysts are promising to replace PGM (platinum group metal) to accelerate oxygen reduction reaction due to their excellent electrocatalytic performance. However, the inferior intrinsic activity and poor active site density confining further improvement in their performance. Modulating the electronic structure and reasonably designing the pore structure are widely acknowledged effective strategies to boost the activity of the M–N–C catalysts. However, it is a great challenge to form abundant pores to regulate the electronic structure via the facile method. Herein, a hierarchical, porous dual-atom catalyst FeNi-NPC-1000 has been architectured by the Na2CO3template method and bimetallic doping modification strategy. Benefitting from the optimized pore and electronic structure, the as-prepared FeNi-NPC-1000 possesses a high specific surface area (1412.8 m2g–1) and improved ORR activity (E1/2= 0.877 V vs RHE), which is superior to that of Pt/C (E1/2= 0.867 V vs RHE). With the evidence of AC-STEM, XAS, and DFT, the FeNi-N8-C moiety is proven to be the key active site to realize high-efficiency ORR catalysis. When assembled it as an air cathode of ZABs, FeNi-NPC-1000 displays superior discharge performance (Pmax= 367.1 mW cm–2) and a stable battery long-life. This article will provide a new strategy for designing dual-metal atomic catalysts applied in metal–air batteries.

The wide application of direct ethanol fuel cells (DEFCs) was blocked by the sluggish catalytic activity of catalysts, insufficient ionic conductivity of the polymer electrolyte membrane (PEM), and ethanol crossover issues. To overcome the problems mentioned above, a novel DEFC system with a polymer fiber membrane (PFM) and nonplatinum catalysts is proposed. In this system, the performance of the anode catalyst Pd/C is significantly promoted by homogeneous Ni-doped SnO2nanoparticles, and the inexpensive permeable PFM is used as a substitute for the PEM. Due to the remarkable catalytic activity and the optimized resistance, the PFM-based DEFC exhibits encouraging performance, which can afford a peak power density of 47.4 mW cm−2with a porous NiCo2O4cathode catalyst. Moreover, it can operate continuously for 100 h with only 4.56% drop in electrical output. Therefore, this study provides a very effective strategy for optimizing DEFCs with low cost and high performance.

The nitrogen coordinated single cobalt atoms embedded in carbon matrix, i.e., Co/N/C material, is cost-efficient and free from iron-ion induced Fenton reagent, which has been thus considered as a promising candidate to replace the well-accepted Pt-based and Fe/N/C materials for oxygen reduction reaction (ORR). Recently, the pyrolysis of metal–organic framework (MOF) precursors has been investigated to achieve well-defined Co/N/C catalysts with high ORR activity. However, the relationships among the composition/structure of MOF precursor, the derived catalysts, and ORR performance have been rarely touched in specialty, while the regulations to achieve single-atom Co/N/C catalysts derived from MOF are confusing. Herein, we engineer several Co-doped MOF (zeolitic imidazolate frameworks, to be specific) precursors with different compositions and structures by tuning synthesis protocols (e.g., ratios, cobalt sources, and reaction time) and investigate the derived catalysts and their ORR properties. The regulations to single-atom Co/N/C are revealed in this work. The superior ORR activity and durability of the optimized Co/N/C catalysts are revealed and attributed to the well-defined Co–Nxmoieties and their stable nanostructures.

Recovery of propylene from polypropylene (PP) purge stream is of great importance due to both more efficient conversion of the monomers and environmental protection. Herein, eight stable metal–organic frameworks (MOFs) with various topological structures were synthesized and their C3H6/N2separation performances were studied.The results indicate that CAU-1, an Al-MOF with ultramicroporous structure and amine-decorated function site, shows prominent C3H6/N2liming selectivity among these MOFs. The ideal adsorbed solution theory (IAST) selectivity of CAU-1 is up to 236 under ambient condition, surpassing other reported porous materials. In addition, the high recovery efficiency (>99%) obtained by breakthrough experiments, good regenerability, and high stability under harsh chemical conditions suggest the great potential of CAU-1 in practical industrial application. Our work demonstrates that the ultramicroporous structures and polar groups in CAU-1 play key roles for C3H6/N2separation, which provides a guideline to design and synthesize high-performance MOFs in propylene recovery from polypropylene off-gas.

Proton exchange membrane fuel cells (PEMFCs) are leading candidates in the utilization of clean energy resources for application in transportation, stationary, and portable devices. In PEMFCs, cathode catalysts are crucial for overall performance and durability due to kinetically slow oxygen reduction reactions (ORR). Because platinum (Pt), a state-of-the-art ORR catalyst, is rare and expensive, the development of high-performance platinum metal group (PGM)-free catalysts is highly desirable for future fuel cell technologies. Among the various PGM-free catalyst formulations, metal and nitrogen co-doped carbon (M-N-C, M: Fe, Co, or Mn) catalysts have exhibited encouraging activity and stability in acidic media for ORR and possess great potential to replace Pt in the future. Therefore, based on our extensive experience in the field of ORR catalysis, this review will comprehensively summarize the basic principles in the design and synthesis of M-N-C catalysts for durable, inexpensive, and high-performance PEMFCs with an emphasis on Co- and Mn-N-C catalysts to avoid Fenton reactions between Fe2+and H2O2, which can generate free radicals and lead to the degradation of catalysts, ionomers, and membranes in PEMFCs. Furthermore, template-free 3D hydrocarbon frameworks as attractive precursors to advanced M-N-C catalysts will be discussed to significantly enhance intrinsic ORR activities in acidic media. In addition, long-term performance durability of M-N-C cathodes will be discussed extensively to provide potential solutions to enhance catalyst stability in PEMFCs. Finally, this review will provide an overall perspective on the progress, challenges, and solutions of PGM-free catalysts for future PEMFC technologies.

Energy consumption continues to rise as society develops worldwide. Meanwhile, a lot of energy is wasted in the form of heat from various devices and systems. Here we report a new power generator, which works based on a difference in H+-ion concentration in a fuel cell structure and produces electricity by harvesting waste heat. The device works via the following three successive processes: H2is oxidized at anode to H+ions, the H+ions then penetrate through a phosphoric acid-treated polybenzimidazole (PBI-PA) membrane and finally the H+ions get reduced to H2at cathode with electrons coming through external circuit from the anode. This system generates electricity at a current density of 21 mA cm−2and a power density of 1.03 mW cm−2at 170 °C. The cell's thermoelectric conversion efficiency at 170 °C is 13.72%, which is higher than typical values reported for many common thermoelectric materials in low temperature regimes. This innovative approach may allow for efficient generation of electricity from waste heat.

Hepatocellular carcinoma (HCC) is a typical hypervascular solid tumor. Vasculogenic mimicry (VM) formed by aggressive tumor cells to mimic vasculogenic networks plays an important role in the tumor malignancy of HCC. Hsp90β promotes endothelial cell-dependent angiogenesis in HCC. However, the relationship between Hsp90β and VM formation is unclear. In this study, we found that Hsp90β is positively correlated with VM and EMT marker proteins in HCC tissues and promotes tube formation, cell migration, and invasion in vitro. Hsp90β interacts with Twist1 and promotes its deubiquitination and stabilization to nuclear translocation and enhances the VE-cadherin promoter activity. Results of in vitro analysis indicate that Hsp90β enhances the tumor VM in tumor-burdened mice, and the Hsp90 inhibitor NVP-BEP800 suppresses VM formation by releasing Hsp90β and Twist1 interaction. This study provides a potential antitumor therapy for inhibiting VM by targeting Hsp90β in HCC.

Background: Cephalosporins are the most widely used semisynthetic antibiotics, which acted on bacterial cell wall (peptidoglycan) synthesis. The key intermediate for fabricating about twothirds of cephalosporins in clinical use is 7-aminocephalosporanic acid (7-ACA), which is derived from chemical or enzymatic deacylation of the natural antibiotic cephalosporin C (CPC). The chemical deacylation process has been replaced by the enzymatic deacylation process because the chemical process required harsh conditions and released toxic waste. Methods: A two-step enzymatic process that utilized D-amino acid oxidase (DAAO) and 7-β-(4- carboxybutanamido)-cephalosporanic acid acylase (GLA) for two successive reactions has been applied for the conversion of CPC to 7-ACA in an industrial scale. Results: To simplify the process and lower costs, the one-pot enzymatic processes were developed by the application of the mono-enzymatic process (application of cephalosporin C acylase or the variants of GLA), di-enzymatic process (simultaneous action of DAAO and GLA) or the tri-enzymatic process (simultaneous action of DAAO, GLA and catalase) for direct conversion of CPC to 7-ACA. Conclusion: Here, we mainly focused on the description of these one-pot enzymatic processes and emphasized on the preparation of the involved biocatalysts.

Background: Cephalosporins are the most widely used semisynthetic antibiotics, which acted on bacterial cell wall (peptidoglycan) synthesis. The key intermediate for fabricating about twothirds of cephalosporins in clinical use is 7-aminocephalosporanic acid (7-ACA), which is derived from chemical or enzymatic deacylation of the natural antibiotic cephalosporin C (CPC). The chemical deacylation process has been replaced by the enzymatic deacylation process because the chemical process required harsh conditions and released toxic waste. Methods: A two-step enzymatic process that utilized D-amino acid oxidase (DAAO) and 7-β-(4- carboxybutanamido)-cephalosporanic acid acylase (GLA) for two successive reactions has been applied for the conversion of CPC to 7-ACA in an industrial scale. Results: To simplify the process and lower costs, the one-pot enzymatic processes were developed by the application of the mono-enzymatic process (application of cephalosporin C acylase or the variants of GLA), di-enzymatic process (simultaneous action of DAAO and GLA) or the tri-enzymatic process (simultaneous action of DAAO, GLA and catalase) for direct conversion of CPC to 7-ACA. Conclusion: Here, we mainly focused on the description of these one-pot enzymatic processes and emphasized on the preparation of the involved biocatalysts.

ABSTRACTObjective: to determine whether functions of endothelial progenitor cells (EPCs) were impaired in patients with permanent atrial fibrillation (AF).Methods: 35 patients with permanent AF (AF group) and 35 age and sex matched controls (control group) were collected. The numbers of circulating CD34+/KDR+cells were determined with flow cytometry in the two groups. Cell proliferation, tube formation, nitric oxygen (NO) and vascular endothelial growth factor (VEGF) were assayed.Results: the numbers of CD34+/KDR+cells were lower in the AF group than the control group (20.01 ± 12.66 /105vs 77.93 ± 58.93 /105，p = 0.022). Colony formation unit (CFU) of EPCs were decreased in AF group compared to the control group（1.76 ± 0.59 CFU vs 3.45 ± 0.82 CFU, p = 0.0000). The AF group had lower cell proliferation ability than control group（0.401 ± 0.113 A vs 0.558 ± 0.130 A, p = 0.004). Tube formation ability was decreased in AF patients compared to controls（434.30 ± 96.22μm/mm2vs 568.09 ± 196.17μm/mm2，p = 0.041). AF patients had lower VEGF secretion than controls (27.35 ± 9.93 ng/L vs 41.86 ± 7.31 ng/L，p = 0.001），they also had lower NO secretion than controls（16.55 ± 6.92μmol/l vs 23.65 ± 5.48，p = 0.012).Conclusions: proliferation, tube formation and paracrine of EPCs were reduced in patients with permanent AF.

To mimic natural photonic crystals having color regulation capacities dynamically responsive to the surrounding environment, periodic assembly structures have been widely constructed with response materials. Beyond monocomponent materials with stimulus responses, binary and multiphase systems generally offer extended color space and complex functionality. Constructing a rule for predicting response sensitivity can provide great benefits for the tailored design of intelligently responsive photonic materials. Here, we elucidate mathematical relationships between the response sensitivity of dynamically structural-color changes and the location distances of photonic co-phases in three-dimensional Hansen space that can empirically express the strength of their interaction forces, including dispersion force, polarity force, and hydrogen bonding. Such an empirical rule is proven to be applicable for some typical alcohols, acetone, and acetic acid regardless of their molecular structures, as verified by angle resolution spectroscopy, in situinfrared spectroscopy, and molecular simulation. The theoretical method we demonstrate provides rational access to custom-designed responsive structural coloration.

•Antibiotics, biocides and antimicrobial Chinese herbs (ACHs) might share some bacterial resistance mechanisms.•Following induction by sub-MICs of chlorhexidine and Rhizoma coptidisextract, bacteria became cross-resistant to antibiotics.•Strategies are called for to control the abuse of antibiotics, biocides and ACHs.

The shape control of platinum nanocrystals is significant to the enhancement of their catalytic performance in terms of activity and selectivity. However, it still remains a major challenge to prepare Pt nanocrystals with tunable shape and clean surface in an eco-friendly way. This article develops a facile and green strategy to prepare well tuned platinum nanocrystals employing poly(diallyldimethylammonium chloride) (PDDA) as the capping agent, reductant, and stabilizer simultaneously in a facile hydrothermal process. It is identified that the variation of PDDA concentration is crucial to control the growth of crystalline facets, leading to the formation of cubic, truncated cubic, and octahedral Pt nanocrystals with sizes tunable from ca. 17 nm to ca. 50 nm. The resultant Pt nanocrystals exhibit excellent electrocatalytic activity and stability toward the oxygen reduction reaction (ORR) in acidic media compared with those of commercial Pt black and the state-of-the-art Pt/C catalyst. It is proposed that the preferential Pt surface and the decoration of PDDA, which modulates the electronic structures and electrooxidation of Pt nanocrystals, synergistically contribute to the enhanced catalytic performance.

The effective optimization methods are needed to reduce the thrust ripple for the tubular flux-switching permanent magnet linear motor (TFSPMLM), which is significant for reducing the vibration, and improving the reliability. The auxiliary teeth and core bridge are set and analyzed for the bipolar and single-polar winding structures. On this basis, this paper focused on a new method of the secondary pole pitch fine-tuning which can overcomes the disadvantages of increasing the volume, decreasing the average thrust, adding the cost, and so on. The influences of tuning the secondary pole pitch on the average thrust and the thrust ripple for the different winding structure motors are calculated and analyzed. The conclusion can provide reference for the application of the method of tuning secondary pole pitch to the TFSPMLM for different background demands.

Background:The aim of this study was to compare the host tissue integration process and biomechanical behaviour after implantation of porcine small intestine submucosa (PSIS) and porcine acellular dermal matrix (PADM) grafts in a rat abdominal wall defect model during a long-term follow-up of 360 days.Objectives:Full-thickness abdominal wall defects were created in 40 Sprague–Dawley rats and repaired with either PSIS or PADM grafts. Rats were sacrificed at 14, 30, 90 and 360 days to evaluate the presence of herniation, infection, adhesions and changes in thickness and strength properties of the regenerated tissue at the defect site. Histopathology and immunohistochemistry were performed to evaluate the host tissue integration process assessed by the level of collagen deposition, vascularization and inflammatory host sub-chronic and chronic responses.Results:PADM grafts had greater strength in vitro(p < 0.01). Moreover, the strength of the PADM grafts integrated with the surrounding host tissues was greater than that of the PSIS grafts at 360 days postimplantation (p < 0.05). A stronger integration into the host tissue was observed for the PADM grafts, which showed oriented bands of collagen deposition intermixed with similar newly formed blood vessels compared to that of PSIS grafts after 360 days. The PADM grafts showed slower infiltration of macrophages but developed into a more heavily infiltrated tissue compared to the PSIS grafts (p < 0.05). The level of leukocyte infiltration after implantation was similar in both grafts (p > 0.05).Conclusion:PADM grafts exhibit more delayed but also more effective host integration than PSIS grafts during the 360 days following implantation, supporting the development of more robust abdominal wall strength.

As the offshore drilling expands to deep water, the influences of bottom ball joint corner and lateral force on drilling security become increasingly significant. During the force analysis, the environmental factors (e.g. wind, sea-flow force, sea ice, etc.) are usually taken into account. Besides, the engineering factors considered in research are top tension ratio and drilling vessel drift. In this paper, a finite element model is established by ANSYS to imitate the force condition of marine riser, so as to analyze the influence laws of top tension ratio and drilling vessel drift rate on marine riser stability (i.e. the corner and lateral force on bottom ball joint ) in Beaufort force scale 3 and 8 windy conditions. The results show that the lateral force increases with the drilling vessel drift rate and top tension ratio accordingly by linear mode. For the same tension increasing extent, the greater the drilling vessel drifts, the more increasing range the lateral force appears. The corner on bottom ball joint has a linear relation with the drilling vessel drift rate similarly. However, the corner on the bottom ball joint demonstrates a non-linear decreasing method as “fast followed by slow” due to the increasing top tension ratio. The research plays a role in the security assurance of sub-sea wellhead in deep-water drilling operation.

With the ever increasing energy demands, unconventional gas becomes the new force in energy field. However, shale gas horizontal drillings are prone to instability problems because of the brittleness of gas shale. The casing programs of shale gas wells in China and North America demonstrate that the more drilling problems are encountered with the larger borehole sizes. In the thrust faults, based on vutukuri's size effect theory and Mclamore's failure criteria, a new prediction model of collapse pressure in transversely isotropic rock mass is proposed to analyze the critical mud weight of micro-hole in gas shale formations. The trajectory sensitivity analysis is also carried out. The results show that micro-hole drilling technique in thrust faults can significantly reduce the collapse pressure of directional wells by 12% approximately.

Reservoir pressure will decline generally along with production in the oil and gas development process. There are some problems such as borehole collapse or reduced diameter and lost circulation in drilling of initial production stage in unconsolidated sandstone. As the formation pressure declines the stress around borehole changes, and then collapse pressure and fracture pressure are affected. Especially in directional wells, variation of wellbore stability is more complex with different borehole deviation and azimuth. The calculation models of collapse and fracture pressure in depleted reservoirs were established, and relevant data in unconsolidated sand reservoir of an oilfield in Bohai Sea was used to calculate collapse pressure and fracture pressure of directional wells in the condition of pressure depletion before and after. The results showed that collapse and fracture pressure decreased as formation pressure depletion, and safe drilling fluid density window was wider when drilled to the direction of minimum horizontal principle stress. The calculation results can be reference to drilling design of adjustment wells in unconsolidated sandstones.