This paper developed a calculation method to acquire the yield load P of bone plate during four-point bending test. This method is based on the displacement--force (δ-F) curve function f(M)(δ) obtained from the test, each slope of the curve was calculated using piecewise smooth function and the line segment in f(M)(δ) elastic deformation area was searched by setting the minimum slope T. Slope S was obtained through linear fit so as to build parallel displacement function f(L)(δ). Then, approximating intersection point of f(M)(δ) and f(L)(δ) was obtained through linear interpolation. Thus, yield load P was acquired. The method in the paper was loyal to YY/T 0342-2002 regulation and was liable to program calculation. The calculating process was nothing to do with whether the initial point during the test was preloaded or unloaded, and there was no need to correct the original point. In addition, T was set in an ideal fitting level guaranteed by the fitting coefficient of determination R2, and thus S was very close to the real value, and P was with a high accuracy.
Biomechanical Phenomena ; Bone Plates ; Humans ; Models, Theoretical ; Posture ; Weight-Bearing

Objective To observe the effects of dexmedetomidine hydrochloride on the cisatracurium-induced neuromuscular blockade in geriatric, young and middle-aged patients. Methods Forty elderly patients and forty young and middle-aged patients undergoing elective abdominal surgery under general anesthesia were randomly divided into 4 groups ( n=20 each):elderly dexmedetomidine hydrochloride group (group DE),elderly control group (group CE),young and middle-aged dexmedetomidine group (group DY) and young and middle-aged control group (group CY).In groups DE and DY,a loading dose of 0.5 μg?kg-1 dexmedetomidine was intravenously infused over 10 min before induction of anesthesia,respectively,followed by infusion at a rate of 0.4μg?kg-1?h-1 until the end of surgery.Equal volume of 0.9% sodium chloride was given in groups CE and CY.Anesthesia was induced with midazolam,fentanyl,propofol and cisatracurium 0.15 mg?kg-1.Four groups were maintained with infusion of propofol and remifentanil. Neuromuscular blockade was maintained with continuous cisatracurium infusion in the four groups and was monitored with TOF-Watch SX acceleromyography at the adductor pollicis.The onset time,TOF no reaction period,duration of action,the amount of cisatracurium consumption,and the spontaneous recovery index ( T1 25% to 75%) were recorded. Results The four groups were comparable in the demographic data.Intubation conditions,the onset time and recovery index were not significantly different among the four groups. The duration of blockade action in groups DE and DY was ( 61. 1 ± 8.9) min and (53.6±9.3) min,which was significantly longer than that in group CE [(49.9±5.8) min] and group CY [(44.8± 6.4) min] (P<0.01).The duration of blockade action was significantly longer in groups DE and CE than in groups DY and CY (P<0.05).The amount of cisatracurium consumption in groups CE and CY was significantly higher than that in groups DE and DY (P<0.05). Conclusion The neuromuscular blockade is longer and the requirement of cisatracurium is less in elderly patients than in young and middle-aged patients.Continuous infusion of dexmedetomidine hydrochloride can't accelerate the onset time of cisatracurium.But duration of action is prolonged and the amount of cisatracurium consumption is lower in patients with infusion of dexmedetomidine hydrochloride.

OBJECTIVEA method for determined oxygen permeability (Dk) of finished soft contact lens.

METHODSOxygen permeability(Dk) of 10 group finished soft contact lens was determined by polarographic method, and the values were linearly calibrated using the measured and established Dk values of the specified reference materials.

RESULTSOnly one Dk value fell outside of the requirement of GB 11417.3-2012 tolerance for Dk (± 20%).

CONCLUSIONIt is great practicability when determined the oxygen permeability (Dk) of finished soft contact lens by polarographic method which were linearly calibrated using the measured and established Dk values of the specified equal thickness reference materials without the measured lens customized 4 different thickness.

Objective: To observe the relationship between impaired myocardial untwisting and left ventricular diastolic dysfunction in patients with autoimmune diseases (AD). Methods: In this retrospective study, 95 AD patients (27 males, (38.6±14.2) years old) were enrolled as AD group and 71 gender and age matched healthy subjects (24 males, (37.6±12.2) years old) were enrolled as control group, all underwent transthoracic echocardiography and two-dimensional speckle-tracking echocardiography (STE) in our hospital between January 2014 and June 2018. Left ventricular untwisting and diastolic function parameters were measured. Multiple logistic regression analysis was used to identify related factors of left ventricular diastolic dysfunction in AD patients. Receiver operating characteristic (ROC) curve was used to identify the diagnosis value of untwisting parameters for left ventricular diastolic dysfunction in AD patients. Results: Compared with control group, left ventricular ejection fraction was lower (58(47, 66)% vs. 67 (62, 71) %, P<0.001), E/e′ was higher (10.78 (7.28, 13.65) vs. 6.30 (5.55, 7.25) , P<0.001), isovolumic relaxation time was longer (73.5 (56.5, 88.0) ms vs. 62.0 (58.0, 68.5) ms, P<0.001),and untwist slope during isovolumic relaxation period (USIR) was lower (31.92 (14.09, 54.92) °/s vs. 59.90 (40.09, 87.18) °/s, P<0.001) in AD group than in control group. Multiple logistic regression analysis showed heart rate (OR=0.885, 95%CI 0.840-0.931, P<0.001), E/e′ (OR=0.655, 95%CI 0.537-0.798, P<0.001) and USIR (OR=0.986, 95%CI 0.974-0.998, P=0.020) were independently related with left ventricular diastolic dysfunction in AD patients. ROC curve showed that area under the curve (AUC) was 0.919 (P<0.001), sensitivity was 87.6%, and specificity was 88.7%, when combining the heart rate, E/e′, and USIR as assessment parameters for the diagnosis of left ventricular diastolic dysfunction in AD patients at a cutoff of 0.51. Conclusions Impairment of myocardial untwisting indicates the presence of early stage left ventricular diastolic dysfunction in AD patients. USIR may be a sensitive parameter to evaluate early stage left ventricular diastolic dysfunction in AD patients.

Based on the Gullstrand I model eye, a simplified model eye for testing fundus imaging device is designed. The model eye can reach the following requirements:(1) The refractive characteristics of the ocular refractive tissue are simulated, and the equivalent focal length in air is 17 mm; (2) The differences between relative refractive index differences of the adjacent materials of the simplified model eye and relative refractive index differences of any adjacent two layers (cornea and aqueous humor, aqueous humor and lens, lens and vitreous body) of the Gullstrand I model eye are not more than 1%; (3) In the case of the incident aperture diameter of 3 mm, the differences of radii of the diffuse spots formed by the paraxial light and the axial light are not more than 15%; (4) The differences of angles of chief ray and tangent line of the fundus are not more than 1°; (5) In the case of the incident aperture diameter of 3 mm, the differences of MTF values of the near axis light are not more than 0.1. The simplified model eye can be expected to be used for testing fundus imaging device instead of the test method in ISO 10940:2009 Ophthalmic instruments-Fundus cameras.
Cornea ; Fundus Oculi ; Lens, Crystalline ; diagnostic imaging ; Refraction, Ocular

OBJECTIVE: To establish a method for measuring the photoelectric performance index (luminance response characteristic and luminance tolerance) of medical electronic endoscope. METHODS: Based on the clinical application and product features of medical electronic endoscope, the umbrella grayscale test chart and the adjustable gray scale test chart are designed and made from two aspects of distribution and density differential. RESULTS: The influence of gray scale arrangement, background illumination intensity and illumination spectrum on photoelectric performance measurement of electronic endoscope is verified by test. CONCLUSIONS It is a reference for the design analysis, evaluation and modification of electronic endoscope product photoelectric part, whether it is suitable for fast detection of umbels and more accurate gray scale test chart.
Electronics, Medical ; Endoscopes ; Light ; Quality Control

Based on the analysis of the theoretical calculation model of axial resolution of optical coherence tomograph for the posterior segment of the human eye, a set of testing device for measuring its axial resolution is designed and developed. In view of a commercial ophthalmic optical coherence tomograph in clinical use, its axial resolution is calculated to be 5.07 μm theoretically, and the actual measurement value is 5.45 μm. The uncertainty of the detection device is evaluated and the result is (5.45±0.10) μm. The measurement error introduced by the testing device is very small. Meanwhile, the axial resolution measured by the testing device meets the requirements of the instrument(≤ 6 μm).
Algorithms ; Eye ; diagnostic imaging ; Humans ; Tomography, Optical Coherence ; Uncertainty