Clinical outcomes of S2 Alar-Iliac screw technique in the treatment of severe spinal sagittal imbalance: a retrospective 2-year follow-up study

Background: The treatment of adult spinal deformity (ASD) remains a significant challenge, especially in elderly patients. This study aimed to evaluate the outcomes of the S2AI screw technique in the treatment of severe spinal sagittal imbalance with a minimum 2-year follow-up.Methods: From January 2015 to December 2018, 23 patients with severe degenerative thoracolumbar kyphosis who underwent placement of S2AI screws for long segment fusion were retrospectively reviewed. Patients were divided into group A (no mechanical complications, 13 cases) and group B (with mechanical complications, 10 cases) according to the occurrence of mechanical complications at the last follow-up. Radiographic parameters were compared between groups preoperatively, 1 month postoperatively and at the last follow-up. Risk factors for mechanical complications were analyzed.Results: The incidence of mechanical complications was 43.5% and the revision rate was 17.4%. At 1 month postoperatively, sagittal correction was better in group A than in group B (p<0.05). The area under the curve for predicting mechanical complications of sacral slope (SS), lumbar lordosis (LL), PI (pelvic incidence)-LL at 1 month postoperatively were 0.762 (p=0.035), 0.896 (p=0.001) and 0.754 (p=0.041) respectively and the best cut-off values were 24.1°, 32.8°and 12.0°. The sagittal correction of both groups was partially lost at the last follow-up.Conclusions: A high incidence of mechanical complications was observed in long-segment corrective surgery with the S2AI screw technique for severe spinal sagittal imbalance. Inadequate sagittal correction is a risk factor for the development of mechanical complications.

Superhydrophobicity, Microwave Absorbing Property of NiFe 2

Magnetic NiFe2O4 nanoparticles were successfully deposited on the wood surface via a hydrothermal process at 70°C. The surface of the as-prepared magnetic NiFe2O4/wood hybrids (MWHs) was covered by spherical-like NiFe2O4 particles with an average size of 50 nm. MWH exhibited the thermostability, microwave absorbability, and superparamagnetism with saturation magnetization (Ms) of 1.79 emu·g−1. With further modification by 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (FAS-17), MWH expressed superhydrophobic performances with a water contact angle of 158°. Its superparamagnetism stably remained under harsh conditions after chemical solutions corrosion and physical frozen test

One-Step Preparation of Graphene Oxide/Cellulose Nanofibril Hybrid Aerogel for Adsorptive Removal of Four Kinds of Antibiotics

Via a one-step ultrasonication method, cellulose nanofibril/graphene oxide hybrid (GO-CNF) aerogel was successfully prepared. The as-prepared GO-CNF possessed interconnected 3D network microstructure based on GO nanosheets grown along CNF through hydrogen bonds. The aerogel exhibited superior adsorption capacity toward four kinds of antibiotics. The removal percentages (R%) of these antibiotics were 81.5%, 79.5%, 79.1%, and 73.9% for Doxycycline (DXC), Chlortetracycline (CTC), Oxytetracycline (OTC), and tetracycline (TC), respectively. Simultaneously, the adsorption isotherms were well fitted to Langmuir model and kinetics study implied that the adsorption process was attributed to pseudo-second-order model. The maximum theoretical adsorption capacities of GO-CNF were 469.7, 396.5, 386.5, and 343.8 mg·g−1 for DXC, CTC, OTC, and TC, respectively, calculated by the Langmuir isotherm models. After five cycles, importantly, the regenerated aerogels still could be used with little degradation of adsorption property. Consequently, the as-synthesized GO-CNF was a successful application of effective removal of antibiotics

Spawns Structure of Rod-Like ZnO Wrapped in Cellulose Nanofibers for Electromagnetic Wave Absorption

Spawns structure of rod-like ZnO wrapped in the cellulose nanofibers was successfully fabricated through a facile one-step hydrothermal method, and their electromagnetic wave absorption properties were investigated. The structure and properties of the composite aerogel were characterized. The enlarged morphology images showed that the as-prepared cellulose nanofiber/ZnO samples were spawns structure of rod-like ZnO wrapped in the cellulose nanofibers. The composite aerogel in a wax matrix exhibited excellent electromagnetic wave absorption performance over 2–18 GHz. The widest absorption bandwidth of 30 wt% contained with reflection loss values less than −10 dB was up to 12 GHz (6–18 GHz) at the thickness of 5.5 mm and the minimum reflection loss value reached −26.32 dB at 15.2 GHz when the thickness of the absorber was 3 mm

Fabrication of Cellulose Nanofiber/AlOOH Aerogel for Flame Retardant and Thermal Insulation

Cellulose nanofiber/AlOOH aerogel for flame retardant and thermal insulation was successfully prepared through a hydrothermal method. Their flame retardant and thermal insulation properties were investigated. The morphology image of the cellulose nanofiber/AlOOH exhibited spherical AlOOH with an average diameter of 0.5 μm that was wrapped by cellulose nanofiber or adhered to them. Cellulose nanofiber/AlOOH composite aerogels exhibited excellent flame retardant and thermal insulation properties through the flammability test, which indicated that the as-prepared composite aerogels would have a promising future in the application of some important areas such as protection of lightweight construction materials

Experimental study on ultra-low raw emissions in diesel/methanol dual fuel engine based on dual-loop EGR

In this paper, an experimental investigation on achieving ultra-low raw emissions in a diesel/methanol dual fuel engine based on dual-loop EGR was carried out. The effect of dual-loop EGR (High pressure EGR and low pressure EGR) on the combustion, performance and emissions of methanol engine has been studied comprehensively. The results show that ultra-low NOx (<0.4g/kWh) and PM (<10 mg/kWh) emissions can be achieved simultaneously in diesel methanol dual fuel engine with the help of EGR. The combustion phase is delayed with the increase of EGR rate in both EGR modes. However, the methanol equivalence ratio and in cylinder combustion temperature in high pressure EGR mode are significantly higher than those in low pressure EGR mode. Therefore, the CO and THC emissions are obviously lower in high pressure EGR mode than that in low pressure EGR mode. The combustion efficiency and brake thermal efficiency of the engine are 1.9% and 9.6% higher in high pressure EGR mode than those in low pressure EGR mode, respectively

Investigation into the Relationship between Super-Knock and Misfires in an SI GDI Engine

The super-knock poses new challenges for further increasing the power density of spark ignition (SI) engines. The critical factors and mechanism connecting regarding the occurrence of super-knock are still unclear. Misfire is a common phenomenon in SI engines that the mixture in cylinder is not ignited normally, which is often caused by spark plug failure. However, the effect of misfire on engine combustion has not been paid enough attention to, particularly regarding connection to super-knock. The paper presents the results of experimental investigation into the relationship between super-knock and misfires at low speed and full load conditions. In this work, a boosted gasoline direct injection (GDI) engine with an exhaust manifold integrated in the cylinder head was employed. Four piezoelectric pressure transducers were used to acquire the data of a pressure trace in cylinder. The spark plugs of four cylinders were controlled manually, of which the ignition system could be cut off as demanded. In particular, a piezoelectric pressure transducer was installed at the exhaust pipe before the turbocharger to capture the pressure traces in the exhaust pipe. The results illustrated that misfires in one cylinder would cause super-knock in the other cylinders as well as the cylinder of itself. After one cylinder misfired, the unburned mixture would burn in the exhaust pipe to produce oscillating waves. The abnormal pressure fluctuation in the exhaust pipe was strongly correlated with the occurrence of super-knock. The sharper the pressure fluctuation, the greater the intensity of knock in the power cylinder. The cylinder whose exhaust valve overlapped with the exhaust valve of the misfired cylinder was prone to super-knock

Study on methanol premixed coupled with EGR to achieve ultra-low emissions in diesel engine

In this paper, an experimental investigation on achieving ultra-low emissions in diesel engine was carried out using intake premixed methanol and EGR technology. The influence of EGR introduction method on combustion and performances were studied comprehensively. The results show that ultra-low NOx (<0.4g/kWh) and PM (<10mg/kWh) emissions can be achieved simultaneously in diesel methanol dual fuel (DMDF) highly premixed low-temperature combustion mode. Compared with low-pressure EGR (LP-EGR), the excess air coefficients under high-pressure EGR (HP-EGR) drops more significantly. At the same EGR rate, the in-cylinder mean temperature and equivalent of mixture are higher under HP-EGR conditions, which results in higher combustion efficiency, lower CO and THC emissions. The maximum brake thermal efficiency of high-pressure EGR is 9.6% higher than that of low-pressure EGR