基于轻量化卷积神经网络的苹果目标检测算法

针对当前苹果检测算法模型参数多、检测实时性差的问题,提出一种基于轻量化卷积神经网络的苹果目标检测算法.首先,用经典轻量化卷积神经网络ShuffleNet V2替换YOLO v5s的主干网络,实现模型的轻量化;然后,用stem模块取代主干网络的图像处理层进行初始特征提取并且嵌入SPPF结构,弥补轻量化带来的精度损失;最后,在边界框的回归损失函数中引入α幂化指标,进一步提高边界框的定位精度.试验结果表明,改进后算法模型的平均精度均值达到95.8%,网络参数量降低了85.6%,在GPU上的单张平均检测时间仅10 ms,满足苹果采摘任务对检测精度和实时性的要求.     

氮对灰铸铁初生奥氏体二次枝晶组织的影响

采用单向凝固方法研究了氮对Ｆｅ－Ｃ－Ｓｉ和Ｆｅ－Ｃ－Ｓｉ－Ｍｎ灰铸铁初生奥氏体二次枝晶组织的影响，结果指出，氮使Ｆｅ－Ｃ－Ｓｉ－Ｍｎ灰铸铁初生奥氏体二次臂间减小，二次枝晶组织细化。     

基于表面等离子体激元共振的葡萄糖光化学传感器的研究

采用自行设计组装的表面等离子体激元共振光化学传感器实验装置，在不加其它化学试剂的条件下，研究了传感器对葡萄糖溶液的响应特性。实验结果表明，此传感器测定葡萄糖溶液的稳定性，可逆性良好，响应迅速，使用寿命长。     

Determination of fluoroquinolones in blood by matrix solid-phase dispersion extraction and CE

A simple and rapid method for the determination of residues of four fluoroquinolones in blood samples was developed. The method was based on matrix solid‐phase dispersion extraction followed by CE with ultraviolet detection. 1‐Butyl‐3‐methylimidazolium tetrafluoroborate aqueous solution was used as the background electrolyte for the separation of fluoroquinolones. The average recoveries of the four fluoroquinolones at two spiked levels ranged from 54.0 to 86.4% for pig blood, and 45.4 to 79.9% for deer blood, with the relative standard deviations <9.45%. Detection limits for the four fluoroquinolones in blood sample ranged from 0.15 to 0.31 μg/mL.     

Ionic liquid foam floatation coupled with solid phase extraction for separation and determination of hormones by high-performance liquid chromatography

The foaming property of ionic liquids (ILs) was found and the factors that can influence foamability of the ILs were investigated. Based on the property of the ILs, the foam floatation-solid phase extraction (FF-SPE) was developed. The IL-based FF-SPE was applied to the extraction and concentration of steroid hormones, including corticosterone, 17-β-estadiol, 17-α-estradiol, 19-nortestosterone, estrone, testosterone, 17-α-hydroxyprogesterone, medroxyprogesterone, chloromadinon 17-acetate, norethisterone acetate, medroxyprogesterone-17-acetate, progesterone, 17-β-estradiol 3-benzoate and testosteron 17-propionate in water samples and then the steroid hormones were determined by high-performance liquid chromatography. The extraction and concentration were performed synchronously in 10 min. Some experimental conditions were examined and optimized. The recoveries ranged from 50.6% to 95.2% for lake water sample and from 53.4% to 98.7% for rain water sample. The precision ranged from 2.43% to 7.43% for the lake water sample and 2.07-7.01% for rain water sample. Based on the foaming property of ILs, the application of foam floatation should be widened.     

The determination of organochlorine pesticides based on dynamic microwave-assisted extraction coupled with on-line solid-phase extraction of high-performance liquid chromatography

A rapid technique based on dynamic microwave-assisted extraction coupled with on-line solid-phase extraction of high-performance liquid chromatography (DMAE-SPE-HPLC) has been developed. A TM₀₁₀ microwave resonance cavity built in the laboratory was applied to concentrate the microwave energy. The sample placed in the zone of microwave irradiation was extracted with 95% acetonitrile (ACN) aqueous solution which was driven by a peristaltic pump at a flow rate of 1.0 mL min⁻¹. The extraction can be completed in a recirculating system in 10 min. When a number of extraction cycles were completed, the extract (1 mL) was diluted on-line with water. Then the extract was loaded into an SPE column where the analytes were retained while the unretained matrix components were washed away. Subsequently, the analytes were automatically transferred from the SPE column to the analytical column and determined by UV detector at 238 nm. The technique was used for determination of organochlorine pesticides (OCPs) in grains, including wheat, rice, corn and bean. The limits of detection of OCPs are in the range of 19-37 ng g⁻¹. The recoveries obtained by analyzing the four spiked grain samples are in the range of 86-105%, whereas the relative standard deviation (R.S.D.) values are <8.7% ranging from 1.2 to 8.7%. Our method was demonstrated to be fast, accurate, and precise. In addition, only small quantities of solvent and sample were required.     

Determination of bovine serum albumin using resonance light scattering technique with sodium dodecylbenzene sulphonate-cetyltrimethylammonium bromide probe

In this paper, the anionic surfactant sodium dodecylbenzene sulphonate (SDBS) and cationic surfactant cetyltrimethylammonium bromide (CTMAB) were used as resonance light scattering (RLS) probe to determine bovine serum albumin (BSA). Based on the weak RLS intensity of SDBS-CTMAB probe and the enhancement of RLS intensity of BSA in the presence of the probe, a simple assay for BSA was developed. The experimental results showed that the formation of three component complex BSA-SDBS-CTMAB is the main reason for the enhancement of RLS intensity of BSA, in which SDBS as a bridge can interact with both BSA and CTMAB. The effects of pH value, incubation time, concentrations of SDBS and CTMAB on the enhanced RLS intensity of BSA were investigated. Under the optimum conditions, the enhanced RLS intensity is proportional to the concentration of BSA in the range from 2.5 x 10(-8) to 2.0 x 10(-6)mol L(-1). The detection limit is 9.7 x 10(-9) mol L(-1) for BSA. The study of foreign substance effect on the determination of BSA indicated that most of metal ions have little effect on the determination of BSA. The results of assay for BSA in synthetic samples were satisfactory.     

Application of pneumatic nebulization single‐drop microextraction for the determination of organophosphorous pesticides by gas chromatography–mass spectrometry

Organophosphorous pesticides (OPPs) including dichlorvos, diazinon, malathion, phenamiphos and chlorpyrifos, in water samples were extracted by pneumatic nebulization single‐drop microextraction (PN‐SDME) and then determined by gas chromatography–mass spectrometry (GC‐MS). Experimental parameters affecting the performances of PN‐SDME, such as flow rate of carrier gas, extraction time and microdrop volume, were examined and optimized. The limits of detection for the analytes were in the range of 0.0014–0.0019 μg/mL. The linear range was 0.0050–0.50 μg/mL, except dichlorvos (0.0070–0.50 μg/mL). Water samples were analyzed and the recoveries of the analytes in the spiked water samples were from 75.2 to 105.3%. The relative standard deviations were lower than 12.7%.     

RE对ZA—27合金组织和性能的影响

为进一步提高ZA-27合金的耐磨性,研究了RE对其组织和性能的影响。实验结果表明;RE使这种合金的晶粒细化,二次枝晶臂间距缩短,α相面积百分数略有增加。加入RE量大于0.1％时,基体中出现含RE硬质点,其形貌随RE加入量的提高而变化。RE的上述行为使ZA-27合金的强度和硬度略有提高,韧性降低,在润滑条件下的耐磨性可大辐度提高。     

西方高等教育管理思想中国化探析

中国近现代高等教育移植于西方高等教育,对其高等教育管理思想也多有借鉴。以“教授治校”和“大学自治”思想为例,中国高等教育百余年的发展历程中,在国家政治管理体制,古代高等教育管理传统,地区和社会的经济、文化差异以及现代大学发展的时代逻辑影响下,这两种传自西方的经典高等教育管理思想逐渐实现了中国化,发展为“教授治学”和“大学自主”的中国高等教育管理思想。而西方高等教育管理思想中国化的发展旨归也必将是形成中国特色的高等教育管理思想,构建中国特色的高等教育管理体制。