High-Efficiency Flicker-Free LED Driver with Soft-Switching Feature.

A novel interleaved DC-DC buck converter is proposed to drive high-brightness light-emitting diodes (LEDs). The circuit configuration mainly consists of two buck converters, which are connected in parallel and use interleaved operation. Through interleaved operation, the power capability of the converter is doubled. Traditionally, two individual inductors are used in the two buck converters. The difference between conventional parallel-operated buck converters using two energy storage inductors and the proposed circuit is that the proposed circuit uses two small inductors and a coupled inductor that replace the two inductors of the buck converters. In this way, both buck converters can be designed to operate in discontinuous-current mode (DCM), even if the magnetizing inductance of the coupled inductor is large. Therefore, the freewheeling diodes can achieve zero-current switching off (ZCS). Applying the principle of conservation of magnetic flux, the magnetizing current is converted between the two windings of the coupled inductor. Because nearly constant magnetizing current continuously flows into the output, the output voltage ripple can be effectively reduced without the use of large-value electrolytic capacitors. In addition, each winding current can drop from positive to negative, and this reverse current can discharge the parasitic capacitor of the active switch to zero volts. In this way, the active switches can operate at zero-voltage switching on (ZVS), leading to low switching losses. A 180 W prototype LED driver was built and tested. Our experimental results show satisfactory performance.

Restoration of the Phenotype of Dedifferentiated Rabbit Chondrocytes by Sesquiterpene Farnesol.

Osteoarthritis (OA) is a joint disorder characterized by the progressive degeneration of articular cartilage. The phenotype and metabolism behavior of chondrocytes plays crucial roles in maintaining articular cartilage function. Chondrocytes dedifferentiate and lose their cartilage phenotype after successive subcultures or inflammation and synthesize collagen I and X (COL I and COL X). Farnesol, a sesquiterpene compound, has an anti-inflammatory effect and promotes collagen synthesis. However, its potent restoration effects on differentiated chondrocytes have seldom been evaluated. The presented study investigated farnesol's effect on phenotype restoration by examining collagen and glycosaminoglycan (GAG) synthesis from dedifferentiated chondrocytes. The results indicated that chondrocytes gradually dedifferentiated through cellular morphology change, reduced expressions of COL II and SOX9, increased the expression of COL X and diminished GAG synthesis during four passages of subcultures. Pure farnesol and hyaluronan-encapsulated farnesol nanoparticles promote COL II synthesis. GAG synthesis significantly increased 2.5-fold after a farnesol treatment of dedifferentiated chondrocytes, indicating the restoration of chondrocyte functions. In addition, farnesol drastically increased the synthesis of COL II (2.5-fold) and GAG (15-fold) on interleukin-1ß-induced dedifferentiated chondrocytes. A significant reduction of COL I, COL X and proinflammatory cytokine prostaglandin E2 was observed. In summary, farnesol may serve as a therapeutic agent in OA treatment.

Iatrogenic Lateral Plantar Nerve Injury After Endoscopic Plantar Fascia Release: A Case Report.

We present a 57-year-old female patient with iatrogenic lateral plantar nerve injury caused by endoscopic surgery for plantar fasciitis. Nerve grafting surgery was recommended, but the patient refused further surgical intervention because of personal reasons. After 1-year follow-up in outpatient clinics, she achieved only slight improvement in the lateral foot symptoms and still required oral analgesics for pain control. The purpose of this case report is to remind physicians of such a rare and serious complication that can occur after endoscopic surgery for plantar fasciitis. Good knowledge of anatomy and skilled surgical technique could decrease this type of complication.

Investigation of a Modified Novel Technique in Bilateral Sagittal Splitting Osteotomy Fixation: Finite Element Analysis and In Vitro Biomechanical Test.

PURPOSE: To evaluate the biomechanical properties of the modified novel 2-hole monocortical plate fixation (2HMCPf) and traditional 4-hole monocortical plate fixation (4HMCPf) techniques in bilateral sagittal splitting osteotomy (BSSO) synthesis using a finite element analysis (FEA) and an in vitro biomechanical test with the application of a shearing loading force on a sawbone mandible model. MATERIALS AND METHODS: A three-dimensional mandible models were generated using the geometry obtained from the computerized tomography image of a sawbone mandible. Plates and screws were generated and combined with the mandible in a CAD environment. The 2HMCPf and traditional 4HMCPf techniques for BSSO osteosynthesis were then analyzed under the occlusal load using the FEA. An in vitro biomechanical test was executed to verify the result of FEA. The force on fixation failure and pattern of failure were recorded. RESULTS: The results revealed that the von Mises Stress on the mandible cortical bone (75.98 MPa) and the screw/plate (457.19 MPa) of the 2HMCPf group was lower than that of the 4HMCPf group (987.68 MPa, 1781.59 MPa). The stress concentrated on the central region of the 4HMCPf group and the distal set of the 2HMCPf group. In vitro study using the sawbone mandible model showed mechanical failure at the region of the proximal segment near the osteotomy site with the 4HMCPf group (average 32.198 N) but no failure on the fixation sites with the 2HMCPf group. Instead, the mandible sawbone fractured on the condyle neck region (average 44.953 N). CONCLUSION: From the biomechanical perspective, we proved that the 2HMCPf method was able to withstand a higher shearing loading force than the 4HMCPf fixation method in BSSO osteosynthesis.

Longitudinal investigation of ischemic stroke using magnetic resonance imaging: Animal model.

BACKGROUND: Arterial embolism is a major cause of ischemic stroke. Currently, digital subtraction angiography (DSA) is the gold standard in clinical arterial embolization examinations. However, it is invasive and risky. OBJECTIVE: This study aims to longitudinally assess the progression of carotid artery embolism in middle cerebral artery occlusion animal model (MCAO) using magnetic resonance imaging (MRI) techniques. METHODS: Turbo spin echo (TSE), time of flight magnetic resonance angiography (TOF-MRA) and diffusion weighted magnetic resonance imaging (DWI) were used to evaluate the image characteristics of cerebral tissues at 1, 2, 3, 7, 14, 21 and 28 days after MCAO microsurgery on Sprague-Dawley (SD) rats. Quantitative analysis was performed and compared in MCAO hemisphere and contralateral normal hemisphere. Furthermore, pathologic section using triphenyl tetrazolium chloride (TTC) stain was performed as well. RESULTS: TOF-MRA showed carotid signal void in the embolism side, which is evidence of artery occlusion. The used MRI techniques showed that edema gradually dissipated within one week, but there was no significant change afterwards. The time-varying signal intensity of MRI techniques in MCAO hemisphere changed significantly, but there were no significant changes in contralateral normal hemisphere. Cerebral injury was also confirmed by analysis of pathology images. CONCLUSIONS: The MCAO animal model was successfully established on SD rats using the microsurgery to assess arterial embolization of intracranial tissue injury.

Effects of Homocysteine on white matter diffusion parameters in Alzheimer's disease.

BACKGROUND: The clinical features of Alzheimer's disease (AD) are related to brain network degeneration, and hyperhomocysteinemia is related to greater white matter hyperintensities. We investigated the changes in four diffusion tensor imaging parameters in the white matter of patients with early stage AD, examined their associations with homocysteine level, and tested the clinical significance of the diffusion tensor imaging parameters and homocysteine level in correlation analysis with cognitive test scores. METHODS: We enrolled 132 patients with AD and analyzed white matter (WM) macrostructural changes using diffusion tensor neuroimaging parameters including fractional anisotropy (FA), mean diffusion (MD), axial diffusivity (axial-D) and radial diffusivity (RD). Two neuroimaging post-processing analyses were performed to provide complementary data. First, we calculated 11 major bundle microstructural integrities using a WM parcellation algorithm, and correlated them with serum homocysteine levels to explore whether the fiber bundles were affected by homocysteine. Second, we used tract-based spatial statistics to explore the anatomical regions associated with homocysteine levels. Changes in cognitive test scores caused by homocysteine served as the major outcome factor. RESULTS: The results suggested that homocysteine levels did not have a direct impact on cross-sectional cognitive test scores, but that they were inversely correlated with renal function, B12 and folate levels. Topographies showing independent correlations with homocysteine in FA and MD were more diffusely located compared to the posterior brain regions in axial-D and RD. In the association bundle analysis, homocysteine levels were significantly correlated with the four diffusion parameters even after correcting for confounders, however no association between homocysteine and WM to predict cognitive outcomes was established. CONCLUSIONS: In our patients with AD, homocysteine levels were associated with renal dysfunction and decreased levels of vitamin B12 and folate, all of which require clinical attention as they may have been associated with impaired WM microstructural integrity and modulated cognitive performance in cross-sectional observations.

Intraosseous leiomyoma of the distal femur: a case report and review of literatures.

BACKGROUND: Leiomyoma is a benign tumor of smooth-muscle origin. They most commonly derived from the uterus. Besides, they were also usually diagnosed in the gastrointestinal tract, skin, and mucous membranes. However, it rarely occurs in the bone. CASE PRESENTATION: The authors reported one case of 56-year-old male with intraosseous leiomyoma of the distal femur. Initially, the patient felt left knee pain for 1 year. Radiographs film disclosed an ill-defined osteolytic lesion with thinning cortex over left distal femoral medial condylar region. Computed tomography (CT) revealed homogenous radiolucent lesion with thinning cortex over the metaphysis of distal femur. Magnetic resonance imaging showed focal marrow replacement by tumor. CT-guide biopsy was performed, and the pathology showed a picture of leiomyoma. Since the definite diagnosis, the lesion was treated with en-bloc resection and endoprosthetic knee joint reconstruction. Satisfied result and disease free were achieved during follow-up. CONCLUSIONS: Intraosseous leiomyoma of the extremities is difficult to be diagnosed due to extraordinarily rare. This rare benign tumor should be included in the differential diagnosis of any relatively intraosseous lesion with benign imaging findings. This is the first published case of primary intraosseous leiomyoma of distal femur after literature reviews.

Treatment of acute unstable distal clavicle fractures with single coracoclavicular suture fixation.

Distal clavicular fractures are less common than fractures involving the middle third of the clavicle. For Neer type IIb distal clavicular unstable fractures associated with disruption of the coracoclavicular ligament, surgical treatment is indicated because of the high risk of nonunion. Various surgical methods can be found in the literature, but no gold standard has been established. We treated 29 consecutive adult patients with unstable distal clavicular fracture with single coracoclavicular suture fixation by using single Mersilene tape (Ethicon, Somerville, New Jersey) and without repair of the torn coracoclavicular ligament or hardware implantation.Twenty-eight patients were followed for at least 46 months (mean, 57.3 months). All fractures healed without further treatment, with a mean time to union of 14.3 weeks. There was no major morbidity, but 2 minor complications occurred. One patient experienced a frozen shoulder on the treated side postoperatively. After adequate rehabilitation, the symptom resolved without any complications at final follow-up. Another patient reported uncomfortable skin tenting due to subcutaneous protrusion of the suture node of the Mersilene tape. After simple subcutaneous surgical removal of the node under local anesthesia, the discomfort resolved. Mean University of California Los Angeles shoulder rating score was 34 (range, 29-35). Twenty patients had excellent results and 8 had good results. All patients resumed their previous levels of activity.