Effectiveness and safety of early lens extraction during par plana vitrectomy for proliferative diabetes retinopathy with mild cataract:a randomized clinical trial

●AIM:To evaluate the effectiveness and safety of early lens extraction during pars plana vitrectomy(PPV)for proliferative diabetic retinopathy(PDR)compared to those of PPV with subsequent cataract surgery.●METHODS:This multicenter randomized controlled trial was conducted in three Chinese hospitals on patients with PDR,aged>45y,with mild cataracts.The participants were randomly assigned to the combined(PPV combined with simultaneously cataract surgery,i.e.,phacovitrectomy)or subsequent(PPV with subsequent cataract surgery 6mo later)group and followed up for 12mo.The primary outcome was the change in best-corrected visual acuity(BCVA)from baseline to 6mo,and the secondary outcomes included complication rates and medical expenses.●RESULTS:In total,129 patients with PDR were recruited and equally randomized(66 and 63 in the combined and subsequent groups respectively).The change in BCVA in the combined group[mean,36.90 letters;95%confidence interval(CI),30.35–43.45]was significantly better(adjusted difference,16.43;95%CI,8.77–24.08;P<0.001)than in the subsequent group(mean,22.40 letters;95%CI,15.55–29.24)6mo after the PPV,with no significant difference between the two groups at 12mo.The overall surgical risk of two sequential surgeries was significantly higher than that of the combined surgery for neovascular glaucoma(17.65%vs 3.77%,P=0.005).No significant differences were found in the photocoagulation spots,surgical time,and economic expenses between two groups.In the subsequent group,the duration of work incapacity(22.54±9.11d)was significantly longer(P<0.001)than that of the combined group(12.44±6.48d).●CONCLUSION:PDR patients aged over 45y with mild cataract can also benefit from early lens extraction during PPV with gratifying effectiveness,safety and convenience,compared to sequential surgeries.

Definition, theory, methods, and applications of the safe and efficient simultaneous extraction of coal and gas

Simultaneous extraction of the coal and gas is an effective method of eliminating coal mine gas disasters while safely exploiting the coal and achieving efficient gas drainage in China, which is widely accepted by the main coal-producing countries around the world. However, the concrete definition of simultaneous extraction is vague and there is little accurate theoretical support for the simultaneous extraction of coal and gas, which makes it difficult to determine an efficient gas drainage method appropriate to the features of coal seams. Based on theoretical analysis, laboratory tests and field observations, a specific definition of simultaneous extraction of coal and gas is proposed after analyzing the characteristics of coal seam occurrences in China, and we developed the mechanism of mining-enhanced permeability and established the corresponding theoretical model. This comprises a process of fracture network formation, in which the original fractures are opened and new fractures are produced by unloading damage. According to the theoretical model, the engineering approaches and their quantitative parameters of ＇unloading by borehole drilling＇ for single coal seams and ＇unloading by protective seam mining＇ for groups of coal seams are proposed, and the construction principles for coal exploitation and gas-drainage systems for different conditions are given. These methods were applied successfully in the Tunlan Coal Mine in Shanxi Province and the Panyi Coal Mine in Anhui Province and could assure safe and efficient simultaneous extraction of coal and gas in these outburst coal mines.

Comparison of simultaneous distillation extraction and solid-phase micro-extraction for determination of volatile constituents in tobacco flavor

The volatile and semi-volatile components in tobacco flavor additives were extracted by both simultaneous distillation extraction and solid-phase micro-extraction. Extraction conditions for solid-phase micro-extraction were optimized with information theory. Then, detection were accomplished by gas chromatography-mass spectrometry. Characteristic of each method was compared. Qualitative analysis and quantitative analysis of 6# tobacco flavor sample were accomplished through both simultaneous distillation extraction and solid-phase micro-extraction. The experimental results show that solid-phase micro-extraction method is the first choice for qualitative analysis and simultaneous distillation extraction is another good selection for quantitative analysis. By means of simultaneous distillation extraction, 20 components are identified, accounting for 92.77% of the total peak areas. Through solid-phase micro-extraction, there are 17 components identified accounting for 91.49% of the total peak areas. The main aromatic components in 6# tobacco flavor sample are propanoic acid, 2-hydroxy-, ethyl ester, menthol and menthyl acetate. The presented method has been successfully used for quality control of tobacco flavor.

Comparison of volatile and semivolatile compounds from commercial cigarette by supercritical fluid extraction and simultaneous distillation extraction

Supercritical carbon dioxide fluid extraction (SFE) was studied as a rapid method for extraction of volatile and semivolatile compounds of Chinese commercial cigarettes. The method was compared with simultaneous distillation and extraction (SDE). Temperature and pressure for the SFE were optimized. The extracts obtained by the two methods showed different characters in composition and represented differently the flavor characteristics of tobacco; compared to SDE, SFE can extract compounds within a shorter time and avoid the thermal degradation and solvent contamination of samples. The extracts by the two extraction methods are complementary for investigating the flavor characteristic of tobacco products.

Simultaneous Determination of Bisphenols and Alkylphenols in Water by Solid Phase Extraction and Ultra Performance Liquid Chromatography-tandem Mass Spectrometry

To establish an analytical method for determination of four bisphenols （BPA, BPB, BPF, and BPS） and two alkylphenols （4-n-OP, 4-n-NP） in water by ultra performance liquid chromatography- tandem mass spectrometry （UPLC/MS/MS）. The water samples were extracted and condensed with solid-phase extraction （SPE） using C18 cartridges and eluted by acetonitrile. Separation was carried out with Acquity BEH C8 column and detection were performed by UPLC/MS/MS. Quantification was calculated by using the internal standard BPA-d16 and 4-n-NP-d8. The linear correlation coefficients of these compounds in the range of 1.0-100.0μg/L were all over 0.999. The minimum detectable concentrations were 0.75-1.0 ng/L, and the recoveries ranged from 87.0% to 106.9%.

Comparison of Headspace Solid-Phase Microextraction with Simultaneous Steam Distillation Extraction for the Analysis of the Volatile Constituents in Chinese Apricot

Volatile constituents in fully mature fruits of apricot （Prunus armeniaca L.） cultivar Xinshiji were extracted using headspace solid-phase microextraction （HS-SPME） and simultaneous steam distillation extraction （SSDE） and then analyzed using capillary gas chromatography and gas chromatography-mass spectrometry. A total of 70 components were identified by HSSPME, including 20 esters, 19 hydrocarbons, 5 alcohols, 5 ketones, 4 acids, 4 lactones, 3 aldehydes, and 10 miscellaneous components, with the esters being the dominant constituent. On the basis of the odor unit values, it is believed that the following compounds probably contributed to the fresh apricot odor： hexyl acetate, β-ionone, butyl acetate, （E）-2-hexenal, linalool, limonene, γ-decalactone, and hexanal. A total of 49 components were also detected by SSDE, including 13 hydrocarbons, 9 alcohols, 7 aldehydes, 9 esters, 4 ketones, 4 lactones, 2 acids, and 1 miscellaneous component, of which the monoterpene alcohols were the dominant constituents. It could be judged from the odor unit values that the following compounds were the major contributors to boiled apricot aroma： β-ionone, linalool, hexyl acetate, γ-dodecalactone, γ- decalactone, （E）-2-hexenal, hexanal, γ-octalactone, phenylacetaldehyde, butyl acetate, limonene, α-terpineol, and δ-decalactone. The results show that HS-SPME is a simple, rapid, and solvent-free method, which is an alternative to the classical SSDE.

Current situation of simultaneous coal and methane extraction tech- nology in pressure-relieved coalbed group

The importance of simultaneous coal and methane extraction and its significance on green exploitation is stated, and current research situation of simultaneous coal and methane and faced new problems are introduced. The research progress on movement of overlying strata and stresses change in them, cracks development during mining in overlying strata and meth- ane emission under disturbance of mining as well as the changing rules of permeability and methane flow under the disturbance of mining is analyzed. The progress on practice of simultaneous coal and methane extraction is analyzed. The deficiencies of current research and further researching fields on simultaneous coal and methane extraction are pointed out.

FEASIBILITY ANALYSIS OF SAFETY SIMULTANEOUS EXTRACTION OF COAL AND COALBED METHANE

Coalbed methane is of great value to extract and utilize in China, but the result of such research is not satisfied yet today.The paper analyzed the storage characteristics of coalbed methane, and then studied the behavior of coalbed methane using the key stratum theory of strata control.According to the features related to coalbed methane accumulations and delivery, the technique for safely simultaneous extraction of coal and coalbed methane is proposed, and benefit analysis is made too.

Acid volatile sulfide and simultaneously extracted metals in superficial sediments from Baihua Lake, China

The bioavailability of five divalent cationic heavy metals （Pb, Cd, Cu, Zn and Ni） in 10 superficial sediment samples from Baihua Lake was assessed based on the molar ratio of simultaneously extracted metals （SEMs） to acid volatile sulfide （AVS）. Atomic absorption spectrometry （AAS） and X-ray powder diffraction （XRD） were used to determine the heavy metal concentrations and examine the mineralogy of the crystalline phases, respectively. The AVS loadings in sediments from Baihua Lake ranged from 64.30 to 350.08 ~rnol/g （dry weight）. The corresponding SEM levels for the sampling sites varied from 1.770 to 14.660 vrnol/g. The molar ratio of SEMs to AVS ranged from 0.014 to 0.084 with a mean value of 0.034. The XRD analysis also confirmed the presence of some metal sulfides in sediments from Baihua Lake. The SEMs/AVS ratios for all sampling sites were significantly lower than 1.0, indicating that AVS in the sediments was sufficient to bind the five heavy metals; thus, these heavy metals are currently not significantly bioavailable to benthic organisms. Comparing the SEMs results to published guideline values for metal toxicity to benthic organisms in sediments, however, suggests that Zn and Ni pose a risk at some sampling locations in Baihua Lake.

Development of RP-HPLC method for simultaneous determination of docetaxel and curcumin in rat plasma: Validation and stability

The purpose of the present research was to develop a suitable, simple, precise, accurate,robust, and reproducible RP-HPLC method for a reliable simultaneous quantification of docetaxel(DTX) and curcumin(CCM) in rat plasma samples using paclitaxel(PTX) as an internal standard. The samples were assayed by the Agilent 1260 Infinity HPLC instrument using a Capcell Pak C8 column(4.6 mm × 150 mm, 5 μm) under isocratic conditions. The mobile phase consisted of acetonitrile and triple distilled water(40/60, v/v) with a flow rate of 1.0 ml/min. The eluent was monitored at 230 nm for simultaneous measurement of curcumin and docetaxel. The method was validated by determining system suitability, selectivity, sensitivity, linearity, inter-day and intra-day precision, accuracy, robustness, and stability in accordance with the guidelines of the United States Food and Drug Administration(FDA).The developed chromatographic method proved to be simple, precise, accurate, robust and reproducible. Moreover, the samples showed stability at room temperature over a period of 48 h. Thus, this method would be employed for routine simultaneous quantification of docetaxel and curcumin in rat plasma samples.

Determination of Selenium in Water by Vortex-Assisted Cloud-Point Extraction Combination with Fluorescence Detection

A simple vortex-assisted cloud-point extraction(VA-CPE)method combined with the fluorescence(FL)strategy was developed to extract and determine inorganic Se(IV)in environmental water.Toluene was used as an extraction reagent,and Se(VI)was reduced to Se(IV)by subjecting its solution in 4 mol/L HCl to microwave heating for generating a yellow piazselenol complex using 3,3'-diaminobenzidine(DAB)and Se(IV).The concentration of the complex exhibited an excellent linear relation with the FL at 560 nm with an excitation wavelength of 420 nm.In addition,the effects of the toluene volume,pH,and VA-CPE parameters were investigated and the interference from coexisting ions was also studied.This method was successfully applied to determine the concentration selenium in environmental water samples with a detection limit of 0.05μg/L in the line range from 0.50μg/L to 50.00μg/L.

基于点线特征融合的实时视惯SLAM算法

为了在光照不足和低纹理场景中实现移动机器人的高精度实时定位和建图,提出了一种基于视觉点线特征以及IMU特征融合的实时SLAM算法。首先通过跳跃路由策略和自适应阈值策略改进了EDlines算法,提高了线特征提取的质量,从而提高了特征跟踪的有效性。然后将视觉惯性特征紧耦合建立约束,通过滑动窗口和边缘化模型进行非线性优化,实现了高精度高实时性的状态估计。实验证明,所提算法在线特征提取的有效性方面优于传统的线段提取算法,同时SLAM系统的定位精度和鲁棒性均得到有效提升。

基于记忆泊车场景的视觉SLAM算法

随着自动驾驶技术的发展,视觉同步建图与定位(SLAM)技术受到越来越多的关注。在记忆泊车场景中,需要对停车场场景建立先验地图,待汽车再次驶入相同的停车场时,使用视觉SLAM进行场景建图与定位。为使SLAM所建地图的鲁棒性更好、精度和效率更高,文中首先使用轻量化的深度学习算法改善传统特征提取算法在不同场景下鲁棒性较差的不足,用深度可分离卷积代替普通卷积结构,从而大大提升了特征提取效率;接着基于ResNet网络改进Patch-NetVLAD算法,并在MSLS数据集上对改进的残差网络和原始VGG网络进行重新训练,使用图像检索进行粗定位,挑选出候选图像帧,再通过精定位求解相机位姿,完成全局初始化的重定位;在此基础上,使用改进后的词袋算法重新训练不同停车场场景下的图像,将所有算法移植到OpenVSLAM架构中完成实际场景的建图与定位。实验结果表明,文中设计的视觉SLAM系统能够完成地上停车场、地下停车场以及室外半封闭园区道路等多场景的建图,平均纵向定位误差为8.42 cm,平均横向定位误差为8.30 cm,均达到工程要求。

退化环境中基于空间几何特征的激光SLAM方法

针对同步定位与地图构建(SLAM)在无全球定位系统(GPS)信号、缺乏环境特征纹理的退化环境中出现定位失败、建图重叠漂移和无法实时运行的问题,提出了一种基于空间几何特征的激光SLAM方法。算法前端设计了一种基于空间线面几何特征的特征点提取方式,依据点线面约束构建点云配准残差函数,采用高斯-牛顿法优化残差以实现点云配准。算法后端基于关键帧构建子图,通过子图间的map-to-map匹配来获得精确位姿,采用插值融合前后端位姿,实现了全局定位优化。仿真与实际退化环境中的实验结果表明:所提算法在20 m的里程计测试中位姿估算误差小于5%;退化环境中的建图效果优于Hector、Gmapping和Cartographer算法,地图更新平均速度提高近4倍。

生牛乳中游离寡糖的提取工艺优化

为提取生牛乳中游离寡糖,并且排除乳中蛋白质和乳糖的干扰,利用乙腈在不同提取条件(反应时间、相对离心力、反应温度和料液比)下去除蛋白质沉淀并提取总糖,并通过优化Sep-Pak C18固相柱和石墨碳柱条件对游离寡糖进行富集、纯化,减少乳糖的干扰,利用高效液相色谱法测定乳糖去除率。结果显示,生牛乳中寡糖最佳提取条件为反应时间2.5 h,相对离心力4 000×g,反应温度-1℃,料液比1∶2(g/mL)。在该提取条件下,蛋白质去除率为93.5%,总糖含量为48.42 mg/mL。利用4%乙腈(含0.1%三氟乙酸)冲洗石墨碳柱可将游离寡糖样品中大部分乳糖去除,乳糖去除率达98.91%。

同时蒸馏萃取结合气相色谱-质谱联用解析不同酿酒原料蒸煮香气成分

为了探究不同酿酒原料蒸煮香气及混蒸混烧工艺对白酒风味组的影响,利用同时蒸馏萃取(simultaneous distillation extraction,SDE)结合气相色谱-质谱联用技术分别对6种不同原料(高粱、大米、玉米、糯米、小麦及其组合)的蒸煮香气及其与酒醅混合蒸煮的香气进行解析,并结合香气活度值(odor activity value,OAV)找出其中重要的香气物质。结果表明,原料蒸煮的重要香气物质有2-正戊基呋喃、己醛、己酸、十四酸乙酯、1-辛烯-3-醇、戊酸乙酯、反-2-庚烯醛和反-2-辛烯醛。粮醅混蒸(即原料与酒醅混蒸)的重要香气物质有2-正戊基呋喃、己醛、异戊酸乙酯、丁酸丙酯、己酸甲酯、戊酸异戊酯、4-甲基戊酸、壬酸和肉豆蔻酸等,这些香气物质在白酒中均有检测出,其中,异戊酸乙酯、丁酸丙酯、己酸甲酯、戊酸异戊酯、4-甲基戊酸、壬酸和肉豆蔻酸,可能主要来源于粮醅混蒸产生的香气物质,而2-正戊基呋喃和己醛可能主要来源于原料的蒸煮香气。

富硫型水库沉积物AVS和SEM空间分布特征及重金属风险评价

随着湖库外源性污染的有效控制,沉积物污染特征成为影响湖库水环境质量的关键因素。本文以富硫型水库——汤河水库为研究对象,分析探讨水库沉积物的理化性质、重金属总量、酸可挥发性硫化物(acid volatile sulfide,AVS)和同步提取重金属(simultaneously extracted metals,SEM)的空间分布特征,采用沉积物基准法(sediment quality guidelines,SQGs)和AVS与SEM关系法对重金属可能诱发的生态风险和毒性效应进行评估。结果表明:汤河水库沉积物中AVS含量在0.03~51.75μmol/g之间,并呈现坝前深水区>东支流库区>西支流库区的空间分布特征。根据Pearson相关性分析可知,汤河水库沉积物AVS含量与间隙水中SO^(2-)_(4)浓度、沉积物烧失量(LOI)含量呈显著正相关,与沉积物间隙水中NO^(-)_(3)浓度和沉积物pH呈现显著负相关。间隙水中SO^(2-)_(4)浓度和沉积物LOI含量是控制AVS产量的重要因素。水库沉积物中ΣSEM变化范围为0.52~2.75μmol/g,呈现出东支流库区>坝前深水区>西支流库区的分布规律。水库沉积物中ΣSEM/AVS和ΣSEM-AVS的变化范围分别为0.06~22.73和-49.18~2.44μmol/g,显示出水库坝前深水区表层0~10 cm沉积物不具有生态风险,而东、西支流库区沉积物中的SEM因为不能完全被AVS所固定而存在潜在生态风险。就单一重金属而言,汤河水库坝前深水区和东西支流中部区域沉积物Ni、Cu、Pb和Zn含量均介于临界效应含量(threshold effects level,TEL)值和可能效应含量(probable effect level,PEL)值之间,可产生低级风险毒性效应,但Ni的毒性效应风险接近中级,今后应予以重点关注。富硫型水库沉积物中容易出现高含量AVS,沉积物间隙水中SO^(2-)_(4)和NO^(-)_(3)的浓度是决定沉积物AVS净产量的重要因素。流域内重金属土壤背景值以及工业、采矿产业排放的废水类型直接影响着诱发生态风险的重金属种类。

基于轻量级CNN的视觉SLAM快速回环检测算法

传统基于卷积神经网络(Convolutional Neural Network,CNN)的视觉同步定位与地图构建(Simultaneous Localization and Mapping,SLAM)系统回环检测目前准确率和召回率较高,但其存在特征提取时间较长和特征向量维度过高导致计算量较大等问题。针对上述问题,结合轻量级卷积神经网络MobileNetV3和PCA降维算法,提出了一种基于深度学习的快速回环检测算法。基于MobileNetV3进行特征提取并构建特征矩阵,运用PCA降维算法完成降维以提升运行速度,使用余弦相似度计算各个特征向量间的相似性,并取最大值与给定阈值比较判断是否构成回环。最后,使用New College和City Centre两个公开的数据集验证算法的性能。实验结果表明,相较于传统的CNN回环检测方法,提出的算法在保证准确率和召回率的同时,运行速度更快,较好的满足了视觉SLAM系统准确性和实时性的要求。

基于GC−MS/O和OAV技术分析雪茄烟叶关键香气物质

为分析雪茄烟叶的关键香气物质,采用同时蒸馏萃取(SDE)和固相微萃取(SPME)法对香气物质进行提取,利用气相色谱–质谱/嗅闻联用技术(GC−MS/O)和香气活力值(OAV)技术对雪茄烟叶香气物质进行确定,并通过香气重组实验进行验证.结果表明:①两种提取方法共得到75种香气物质,包括醇类、醛类、酯类、酸类、烃类、杂环类和其他类;②SDE法所得雪茄烟叶提取物主要体现花香和果香香韵,SPME法所得雪茄烟叶提取物主要体现果香香韵;③结合GC−MS/O和OAV技术能够有效确定雪茄烟叶的关键香气物质.基于上述分析结果的香气重组物进行卷烟加香实验能够彰显雪茄特征风味,显著提高卷烟的感官品质.

不同方法提取姜黄油挥发性化学成分GC-MS分析

采用同时蒸馏萃取法(SDE),选择石油醚、正己烷、乙醚3种萃取剂及纤维素酶、盐析2种辅助方式共五种方式提取姜黄油,比较不同提取方法对姜黄油挥发性化学成分的影响。利用GC-MS法鉴定姜黄油的挥发性化学成分,归一化法计算挥发性化学成分相对百分含量,并对数据进行主成分和聚类分析。结果表明:用5种提取方法共鉴定出84种化合物,其中共有化合物24种。主成分分析结果显示4种主成分可反映姜黄油挥发性化学成分的100%的信息,芳姜黄酮、姜黄酮、β-姜黄酮、β-倍半水芹烯和α-姜油烯对姜黄风味贡献最大。聚类分析结果表明,5种提取方法可分为3类即T1和T2一类,T4一类,T3和T5一类。24种化合物被聚为2类,其中α-姜油烯等5种含量最多的化合物聚为一类。不同提取方法对姜黄油的提取效果影响较显著,以纤维素酶辅助SDE提取方式和盐析辅助SDE提取方式更为明显。