Background: Recurrent intervertebral disc herniation and an exacerbated degenerative process have been identified as the most important factors contributing to persistent pain and disability after surgical discectomy.Defects in the annulus fibrosus remain a surgical challenge, as the preference for minimally invasive surgical approaches for lumbar microdiscectomy, surgical access, and the specifics of anatomy limit the types of devices that permit annulus fibrosus repair. Furthermore, the intervertebral disc is a relatively avascular structure, and surgical procedures can accelerate the degenerative disc process. This study aimed to evaluate the clinical safety and efficacy of a novel microdiscectomy annular repair technique combined with an autologous conditioned plasma (ACP) intradiscal injection for the treatment of lumbar disc herniation (LDH).Methods: From July 2017 to December 2018 this study recruited 75 patients with LDH (single segment) and randomly divided these patients into the following three groups: group A, full endoscopic discectomy; group B: full endoscopic discectomy and annular repair; group C, full endoscopic discectomy annular repair and ACP intradiscal injection. The pre-and postoperative neurological function and pain status were evaluated by the visual analog scale (VAS) score and the Oswestry disability index (ODI). Patients were followed up once preoperatively, and at 1, 3, and 6 months postoperatively. Results:The procedure was successfully performed in all cases. No cases required conversion to an open procedure. The preoperative symptoms were alleviated significantly after surgery. The VAS scores for lower back and lower limb pain and ODI score were significantly difference at 1 month, 3 months, 6 months post operation compared to pre-operation scores (P<0.05). For VAS scores of the lower back, the difference between group A and group C was statistically significant (A>C), as was the difference between group B and group C (B>C). Conclusions:Early results showed that the use of the novel full endoscopic annular repair technique and ACP intradiscal injection serial therapeutic model are beneficial for short term outcomes and demonstrates a reduction in symptomatic disc reherniation with low postoperative complication rates. This new serial therapeutic model may significantly improve the symptoms of postoperative lower back pain.
A molecular dynamics (MD) simulation of 35,000 picoseconds (ps) has been carried out to study the conformational interconversions of 1,l-difluoro-4,4dimethylcycloheptane at room temperature using the MM3 force field. The exchange between axial and equatorial fluorine atoms was the only conformational interconversion that occurred, and it took place via the process of pseudorotation. Ring inversions (twist-chair > twist-boat > twistchair) were not observed. The axial-equatorial exchange of the two fluorine atoms took place five times during the MD trajectory of 35,000 ps. The two CH3 groups occupied symmetrical positions (exchangeable by a C2-like rotations, where C2-like means it would be C2 if the fluorines were not present) in the MM3 structures, and during most of the time of the MD trajectory. The methyls occasionally moved off the C2-like axis in the simulated process, mostly because the C2-like axis was momentarily moved so that it did not pass through the ring atom to which the two CH3 groups are LI, CUI, AND ALLINGER bonded. A C2-like symmetry of the twist-chair conformation was maintained approximately during most of the MD simulation. The conformational geometry with the highest energy obtained during the axial-equatorial exchange process was found and used to locate the transition state. The energy barrier for this axial-equatorial exchange was calculated to be 4.7 kcal/ mol, and it compares with the value (5.0 kcal/mol) determined by dynamic nuclear magnetic resonance (NMR).
This paper proposes a method of signal analysis for a semi-active suspension isolation system. A semi-active suspension isolation system is an efficient equipment for vibration isolation and noise reduction in a car. In order to achieve a good vibration isolation effect, it adjusts its damping characteristic according to the excitation signals caused by different road conditions. Thus the key technique of the control of a semi-active suspension isolation system is to classify the excitation signals and analyze them quickly in time. This paper puts forward a signal processing method for these signals. At first, these signals are subdivided into three types, the stationary signal, the non-stationary signal and random signals. Subsequently, it uses the short-time Fourier transform (STFT) to handle them with different window functions in order to find the main frequency of the signal. Especially, the dynamic trend of the main frequency has to be considered for non-stationary signals. The two main parameters of the main frequency of the excitation signal, namely the position and the amplitude, will be obtained by the signal analysis. Then the control system can use them to give the best damping ratio for the damper. Finally, the method is used in a two-stage semi-active vibration isolation system to verify its effect. The experimental results show that it can analyze the signal exactly in time, and obviously enhance the vibration isolation performance of the semi-active suspension isolation system.
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