Sequential injection spectrophotometric determination of nanomolar nitrite in seawater by on-line preconcentration with HLB cartridge

The unstable state of nitrite results in its very low concentration in seawater, which is below the limit of detection （LOD） of conventional techniques of analysis. Some sensitivity-enhanced methods have been proposed for the determination of nitrite at nanomolar level to illustrate the role of nitrite in the marine nitrogen cycle. However, most of previous reports are not widely accepted, because of their complexity and cost equipment or intensive labor requirement. In this study, a simple automatic system for the determination of nanomolar level nitrite using on-line preconcentration with spectrophotometric detection was described..An Oasis HLB cartridge was adopted to quantitatively enrich the pink-colored azo compound, formed from nitrite via Griess reaction. The cartridge was rinsed with water and ethanol （volume fraction is 55%, the same below）, in turn, then eluted by an eluent containing 50% ethanol and 0.25 M（mol/dm^3） H2SO4, and determined at 543 nm with a 2 cm path-length flow cell. Under the optimized experimental conditions, the calibration curve showed a good linearity in the range of 1.4 85.7 aM, and the LOD （3a） was estimated to be 0.5 nM. The relative standard deviations of 7 measurements were 4.0% and 1.0% for the samples spiked at 7.1 and 28.6 nM, respectively. The recoveries for the different natural water samples were between 92.2%-108.4%. Each HLB cartridge could be reused for at least 50 times. As compared with other SPE methods, the advantages of this method included the free of interference from salinity variation and less sample consuming. The results of the application of the proposed method to natural water showed good agreement with liquid waveguide capillary cell detection method.

Enzymatic Determination of Glucose by Optical-Fiber Sensor Sequential Injection Renewable Surface Spectrophotometry

On the basis of oxidative decoloration of bromopyrogallol red （BPR） with H2O2, catalyzed by horseradish peroxidase（ HRP）, and the sequential injection renewable surface technique（ SI-RST）, a highly sensitive optical-fiber sensor spectrophotometric method for the enzymatic determination of hydrogen peroxide was proposed. By coupling with a glucose oxidase（GOD）-catalyzed reaction, the method was used to determine glucose in human serum. The considerations in system and flow cell design, and factors that influence the determination performance are discussed. With 100μL of sample loaded and 0. 6 mg of bead trapped, the linear response range from 5.0 × 10^-8 to 5.2 × 10^-6 mol/L BPR with a detection limit（3σ） of 2. 5 ×10 ^-8 mol/L BPR, and a precision of 1.1% RSD（ n = 11 ） and a throughput of a 80 samples per hour can be achieved. Under the conditions of a 8. 7 × 10^ -6 mol/L BPR substrate, 0. 04 unit/mL HRP, 600 s reaction time and a reaction temperature of 37℃, the linear response range for H2O2 was from 5.0 × 10^-8 to 7.0 × 10^-6 mol/L with a detection limit（3σ） of 1.0 × 10^-8 mol/L and a precision of 3.7% RSD （ n = 11 ）. The linear response range by coupling with a GOD-catalyzed reaction was from 1.0 × 10^-7 to 1.0 × 10^-5 mol/L. The method was directly applied to determine glucose in human serum. Glucose contents obtained by the proposed procedure were compared with those obtained by using the phenol-4-AAP method, the error was found to be less than 3%.

Optimization of siRNA Delivery Method into the Liver by Sequential Injection of Polyglutamic Acid and Cationic Lipoplex

Previously, we developed a novel siRNA transfer method to the liver by sequential intravenous injection of poly-L-glutamic acid (PGA) and cationic liposome/siRNA complex (cationic lipoplex). In this study, we examined the effects of the charge ratio (+/-) of cationic liposome/siRNA, molecular weight of PGA and cationic lipid of cationic liposome on the biodistribution of siRNA after sequential injection of PGA plus cationic lipoplex. When 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)/cholesterol (Chol) lipoplex was intravenously injected into mice, the accumulation of siRNA was mainly observed in the lungs. In contrast, when DOTAP/Chol lipoplex was intravenously injected at 1 min after intravenous injection of PGA, siRNA was largely accumulated in the liver. The charge ratio (+/-) of DOTAP/Chol liposome/siRNA did not affect the biodistribution of siRNA after sequential injection. As regards the molecular weight of PGA, the accumulation of siRNA was observed mainly in the liver after the sequential injection of PGA of 20.5, 38, 64 or 200 kDa plus DOTAP/Chol lipoplex. Furthermore, to examine the effect of cationic lipid of cationic liposome on the biodistribution of siRNA, we prepared other cationic liposomes composed of 1,2-di-O-octadecenyl-3-trimethylammonium propane chloride (DOTMA)/Chol, dimethyldioctade-cylammonium bromide (DDAB)/Chol and O,O’-ditetradecanoyl-N-(α-trimethylammonioacetyl)di-ethanolamine chloride (DC-6-14)/Chol. For the cationic liposomes, the accumulation of siRNA was observed mainly in the liver when their cationic lipoplexes were sequentially injected after injection of PGA into mice. From these findings, sequential injection of PGA plus cationic lipoplex could deliver siRNA efficiently into the liver regardless of the charge ratio (+/-) of lipoplex, lengths of PGA and cationic lipid of liposome.

Simple Spectrophotometric Sequential Injection Analysis System for Determination of Serum Calcium

A sequential injection analysis (SIA) system for the determination of total calcium in blood has been implemented. The assay principle is based on the arsenazo III method, in which the indicator’s complex with calcium forms a blue-purple colour. The absorbance peak height at 650 nm was proportional to the calcium content in samples. A linear range was obtained from 2.5 - 15 mg?dL–1 (r2 = 0.999), with a detection limit of 0.430 mg?dL–1 (3σ). Magnesium, glucose, hae-moglobin, and bilirubin at 123, 1,000, 50, and 0.5 mg?dL–1, respectively, were not found to interfere with the proposed system significantly (recovery 99.1% - 104.4%). The sampling frequency was 30 h–1, in which the carry-over effect was negligible (0.69%). The proposed SIA system was successfully applied to the determination of calcium from serum samples (r2 = 0.970;n = 30).

Design of Large Injection Mould for Car Dashboard

The dashboard is the most important part of the large inner decoration of cars;it should not only have enough strength and rigidity,but also have a harmonious body model which can unify the theme.Besides,it needs to reach the goal of lightweight.In order to achieve these three goals,the car dashboard is made by engineering-plastics and adopts the technology of injection moulding.This paper introduces the keys of design and the advanced technology of large injection moulding for car dashboard.

Injectable immunoregulatory hydrogels sequentially drive phenotypic polarization of macrophages for infected wound healing

Regulating macrophage phenotypes to reconcile the conflict between bacterial suppression and tissue regeneration is ideal for treating infectious skin wounds. Here, an injectable immunoregulatory hydrogel (SrmE20) that sequentially drives macrophage phenotypic polarization (M0 to M1, then to M2) was constructed by integrating anti-inflammatory components and proinflammatory solvents. In vitro experiments demonstrated that the proinflammatory solvent ethanol stabilized the hydrogel structure, maintained the phenolic hydroxyl group activity, and achieved macrophages' proinflammatory transition (M0 to M1) to enhance antibacterial effects. With ethanol depletion, the hydrogel's cations and phenolic hydroxyl groups synergistically regulated macrophages' anti-inflammatory transition (M1 to M2) to initiate regeneration. In the anti-contraction full-thickness wound model with infection, this hydrogel effectively eliminated bacteria and even achieved anti-inflammatory M2 macrophage accumulation at three days post-surgery, accelerated angiogenesis and collagen deposition. By sequentially driving macrophage phenotypic polarization, this injectable immunoregulatory hydrogel will bring new guidance for the care and treatment of infected wounds.

Microfluidic sequential injection analysis system based on polydimethylsiloxane (PDMS) chip with integrated pneumatic-actuated valves

A sequential injection analysis (SIA) system based on polydimethylsiloxane (PDMS) chip with integrated pneumatic-actuated valves was developed. A novel SIA operation mode using multiphase laminar flow effect and pneumatic microvalve control was proposed. The sample and reagent solutions were synchronously loaded and injected in the chip-based sample injection module instead of multi-step sequential injection by a multiposition valve and a reciprocating pump as in conventional SIA system. The sample and reagent injection volumes were reduced to ca. 1.1 nL. The present system has the advantages of simple structure, fast and convenient operation, low sample and reagent consumption, and high degree of integration and automation. The system operation conditions were optimized using fluorescein as model sample. Its feasibility in biological analysis was preliminarily demonstrated in enzyme inhibition assay.

On-line solid-phase extraction using alizarin violet functionalized silica gel for determination of trace lead in environmental samples and wastewater by sequential injection spectrophotometry

Trace of Pb(Ⅱ) has been on-line separated and enriched from environmental samples and wastewater by using the self-made alizarin violet functionalized silica gel micro-column coupling with a sequential injection sampling technology. The determination is based on the color reaction of Pb(Ⅱ) with iodide and crystal violet to form an ionic association complex in the presence of polyvinyl alcohol and hydrochloric acid. The use of the microcolumn can prevent the interference of most familiar metal ions, and therefore improve the selectivity and sensitivity of this analytical technique. The proposed method was used for the determination of Pb(Ⅱ) in environmental samples and wastewater. No statistically significant difference was observed between the results determined by the present method and atomic absorption spectrometry.

左右后雾灯边框的顺序阀热流道注塑模设计

结合新能源汽车的左右后雾灯边框注塑时易产生熔接痕和脱模时易变形的问题,设计了1模2腔的侧浇口二板式热流道注塑模具。基于Moldflow模拟分析结果,确定了左右后雾灯边框的最佳浇口位置、浇口数量,通过综合分析塑件尺寸、生产技术和效率等设计了模具的浇注系统、冷却系统、抽芯机构、脱模机构等结构。为合理控制塑件的熔接痕,采用冷流道与热流道相结合的复合流道,利用顺序阀控制进浇点的进浇时间;为了实现高效脱模,将模具引入了斜顶机构、倒装的斜导柱侧抽芯的组合式脱模结构,替代了传统注塑推杆式脱模,采用两侧油缸驱动推板运动的脱模方式。最后,利用UG软件对模具的导向机构、复位机构和其他辅助机构进行分析,完成了模具设计。

小切口正中神经松解术联合穴位注射序贯疗法治疗腕管综合征的效果

目的:探讨小切口正中神经松解术联合穴位注射序贯疗法治疗腕管综合征(CTS)的效果。方法:选择2021年1月—2023年1月钦州市第二人民医院收治的103例CTS患者作为研究对象。按照随机数表法分为对照组(n=52)和观察组(n=51),两组均进行小切口正中神经松解术治疗,对照组术后口服神经营养素药物治疗,观察组术后采用穴位注射序贯法治疗。比较两组治疗效果、腕关节综合征Levine评分及正中神经肌电图指标[感觉传导速度(SCV)、感觉神经动作电位波幅(SNAP)、运动神经末端运动潜伏期(DML)]。结果:观察组总有效率为98.00%,高于对照组的80.00%,差异有统计学意义(P<0.05)。治疗6个月后,两组严重程度、功能状态评分低于治疗前,且观察组低于对照组,差异有统计学意义(P<0.05)。治疗6个月后,两组SCV、SNAP均高于治疗前,DML低于治疗前,且观察组SCV、SNAP高于对照组,DML低于对照组,差异有统计学意义(P<0.05)。结论:小切口正中神经松解术联合穴位注射序贯疗法治疗CTS可有效提高其治疗效果,改善患者腕关节功能,促进神经恢复。

杂合式血液净化序贯疗法与丹参注射液联合治疗重症急性胰腺炎的效果分析

目的分析杂合式血液净化序贯疗法与丹参注射液联合治疗重症急性胰腺炎(SAP)的效果。方法98例SAP患者,使用随机数字表法分为对照组(49例)与研究组(49例)。两组均接受基础治疗,对照组应用杂合式血液净化序贯疗法,研究组在其基础上联合丹参注射液治疗。比较两组患者的临床疗效、症状与体征改善时间、不良反应发生情况。结果研究组患者总有效率95.92%高于对照组的81.63%(P<0.05)。研究组腹痛腹胀消失时间、血尿淀粉酶恢复正常时间、尿恢复正常时间、体温恢复正常时间分别为(4.23±0.95)、(4.15±1.06)、(6.00±0.92)、(5.02±0.85)d,均短于对照组的(6.00±0.86)、(6.45±1.09)、(7.56±1.00)、(6.50±0.79)d(P<0.05)。两组不良反应发生率比较未见差异性(P>0.05)。结论杂合式血液净化序贯疗法与丹参注射液联合治疗SAP效果确切,能够促进患者症状与体征恢复,具有临床推广价值。

一种汽车B柱内饰板注塑模具设计

根据汽车B柱左右内饰板结构复杂、外观质量高、体积大、内部加强筋多、倒扣多等特点,设计了一套“一模两腔”带有顺序阀热流道的注塑模具。采用斜导柱+整体式T形滑块机构与斜顶杆交叉辅助机构实现倒扣、内部异形孔等结构的抽芯脱模。设计了延伸分型面,动模模芯与型腔板一体成型、定模模芯和型芯板一体成型,可大大节省制造成本。浇注系统采用“热流道+U形回弯冷流道+扇形侧向搭接浇口”的设计,减少了塑件熔接痕、缩痕等缺陷,提升了塑件质量。详述了模具模芯结构、热流道浇注系统、冷却水路、排气、导向定位的设计要点,解决了B柱左右内饰板注塑过程中的脱模困难、熔体填充和生产周期长等问题,通过优化组合设计,从整体上简化和优化了模具结构,降低了模具制造成本。

基于气辅成型某汽车把手的注塑模具设计

为保证某汽车把手的注塑模具成型结构及成型质量的可靠性,基于Moldflow进行CAE注射成型模拟,确定以气辅溢流成型法作为模具设计及注射成型的方案。CAE模拟结果显示,该塑件所有效应变形量比采用气辅标准成型法塑件的变形量降低了31.3%,对充填熔体体积精准性要求较低、更容易控制,气体型芯穿透效果好,并得到最合适的浇口位置、最佳注塑工艺参数,以及气辅成型的最佳进气位置、气体延迟时间、气体注射时间、气体压力及气体保压时间等工艺参数。根据成型方案,针对性地设计了油缸驱动的气辅注气针运动机构、料道封闭运动机构及溢料槽。根据塑件产品的结构特征,利用斜导柱驱动滑块机构带动双面斜楔块运动,从而驱动一对滑块镶件相向移动,解决了在空间有限的情况下,伞形齿面及沉孔的抽芯脱模问题;设计了斜导柱驱动滑块抽芯机构,实现了筋条、转轴锥孔等特征的侧向抽芯。为确保气辅成型、塑件顶出等动作按照优化的注塑工艺安全、准确、可靠地运行,针对各运动机构,设计了相应的顺序控制及保障机构。经过注塑生产验证,模具操控调试简单方便,运行安全、准确、可靠,塑件质量稳定,符合设计要求。

基于顺序注塑的大型双色注塑件翘曲研究

以大型双色注塑车灯灯罩作为研究对象,对双色注塑流程中的浇口位置、开启顺序进行深入研究。首先比较三浇口方案和五浇口方案,再对五浇口方案采用正交试验,以2、3浇口打开时间、4、5浇口打开时间、模具温度、浇口位置作为设计变量,共设计了30组试验方案。使用Moldflow软件进行模流分析,分析在不同因素组合下的注射时间、总翘曲程度以及在各个方向上的翘曲情况。在得到结果后,使用Minitab分析软件寻找到最优的参数组合。结果表明:该方案可以有效降低大型双色注塑件的翘曲缺陷,提高产品质量。

河口岸带氨氮原位快速分析方法研究

以自主研发的海水氨氮原位快速分析仪的现场可靠测量为目标,基于改进的靛酚蓝分光光度法建立了一种河口岸带氨氮的快速分析方法。论文基于正交实验分析,研究了不同盐度条件下,全自动快速测量最佳不完全显色反应时间,并确定了给定盐度范围内最佳不完全显色反应时间随盐度变化的规律。研究及分析结果表明,样品盐度为5‰的情况下,基于改进和优化后的靛酚蓝分光光度法,氨氮原位测量仪的检测耗时仅需要60s左右;样品盐度在0‰~25‰范围内,氨氮快速测量的最佳反应时间,随着盐度的增大而逐渐增加,样品盐度为25‰时,检测耗时为180s。光程长度为10cm、显色反应时间为60s时,盐度为5‰的氨氮样品检测下限为0.9945μmol·L^(-1),方法标准工作曲线R2大于0.99,证明改进后的靛酚蓝分光光度法可以满足河口岸带水体中氨氮的原位快速检测。将其应用于湛江湾水体中氨氮时间序列在线监测发现,监测期间氨氮浓度与水体盐度存在很好的负相关关系。与传统的人工检测和流动注射分析方法相比,自主研发的海水氨氮原位快速分析仪检测分析过程中样品和试剂消耗量极少(μL),反应时间短(盐度为5‰时60 s),可适用于河口岸带水体中氨氮的长时间序列原位及在线监测。

分时电价下油田分压周期注水优化研究

为降低由各注水井需求压力不一致导致的阀组节流损失,以泵站总能耗成本最低为目标函数,以站内泵机组及站外注水井服务要求为约束条件,借助数学规划和优化高级建模系统(GAMS)建模编程,调用内嵌分枝减小最优化导航(BARON)求解器求解,建立了一种分时电价下分压周期注水的数学模型。针对实际注水情况,考虑各压力范围注水井组交叉注水与顺次注水2种运行方案,通过对比分析确定了最佳注水方案。研究结果表明,优化后低压注水井组节流损失平均降低约7 MPa,中压注水井组节流损失平均降低约3 MPa,分时分压周期注水方式一周期内能耗成本可降低约13000元,极大降低了现场因节流损失带来的能耗成本,具有良好的经济效益。同时,顺次注水相较交叉注水具有更好的实用价值与可操作性,可为现场实际运行生产提供一定参考。

基于声化学微试剂快速检测方法研究

针对高锰酸盐检测存在试剂用量大,检测周期长等问题,基于超声液体声化反应机理,应用超声辅助消解技术和顺序注射分析技术(SIA),提出了一种高锰酸盐微试剂快速检测方法。基于超声辅助高锰酸盐溶液消解原理,设计消解池结构,采用最小二乘法建立高锰酸盐回归模型。结果表明,超声辅助消解法曲线相关性优于光谱法。基于高锰酸盐指数检测仪行业标准,量程漂移与零点漂移在±5%以下,系统重复性误差为2.51%以内。实验表明,该方法具有一定的应用价值。

基于超声-微纳米气泡辅助技术的可变光程水质多参数检测方法研究

针对目前国家标准分析检测水质多参数方法存在的科学与技术问题,提出了一种基于超声-微纳米气泡(US-MNB)辅助技术、连续光谱法和顺序注射分析法(SIA)的可变光程水质多参数检测新方法。设计水质多参数检测系统,通过检测总磷(TP)、化学需氧量(COD)、氨氮(NH_(3)-N)和六价铬(Cr^(6+))四种水质参数,验证了新方法的可行性。系统设计的核心是基于超声与微纳米气泡相结合的消解室以及具有可变光程功能的光谱扫描检测室,可达到快速消解和稳定检测的目的。同时系统基于国家水质检测标准,优化了水质多参数联合检测流程,并利用分光光度法和顺序注射分析技术对四种水质参数的含量进行连续光谱检测。首先,在常温常压下采用US-MNB辅助技术结合强氧化剂对TP进行消解,同时对检测室中NH_(3)-N参数显色反应后的化合物直接进行光谱扫描测定,消解后,再进行TP的测定。同理,消解COD的同时,对检测室中的Cr^(6+)参数显色反应后的化合物直接进行光谱扫描测定,消解后,再进行COD的测定。整个检测过程所用时间大幅降低,可在短时间内自动完成水质多参数的测定,显著地提高了检测的效率。以上述四种水质参数为测定对象,利用最小二乘法构建回归模型,拟合回归方程并计算相关系数,并绘制各参数的浓度-吸光度标准工作曲线。结果表明:TP标准工作曲线拟合系数≥0.9845,且浓度与吸光度成正相关,重复性(RSD)为3.05%~3.62%,加标回收率为97.8%~103.6%;COD标准工作曲线拟合系数≥0.9987,且浓度与吸光度成负相关,重复性(RSD)为2.12%~2.74%,加标回收率为98.7%~104.7%;NH_(3)-N标准工作曲线拟合系数≥0.9953,且浓度与吸光度成正相关,重复性(RSD)为3.41%~3.59%,加标回收率为99.2%~102.4%;Cr^(6+)标准工作曲线拟合系数≥0.9938,且浓度与吸光度成正相关,重复性(RSD)为3.51%~3.92%,加标回收率为98.9%~109.3%。系统可准确测定水样中TP、COD、NH_(3)-N和Cr^(6+)的含量,且具有良好的稳定性与可靠性。基于超声-微纳米气泡辅助技术的可变光程水质多参数检测方法研究,对于拓宽光谱法在水质多参数快速检测领域的应用以及提升检测效率等方面的研究具有重要作用。

STC柴油机掺烧生物柴油改变喷油提前角研究

针对生物柴油黏性比柴油大,掺混后造成燃油雾化不良、油气混合质量差、着火时刻及滞燃期都发生变化的问题,建立仿真模型,研究在生物柴油最佳掺混比25%(B25)时,改变喷油正时对相继增压(Sequential Turbo Charging,STC)柴油机燃烧和排放性能的影响,并确定最佳喷油提前角。仿真结果表明:在25%和75%负荷,随着喷油提前角提前,缸内压力、缸内温度上升,指示燃油消耗率下降,NO排放逐渐上升,而Soot排放下降。利用多目标灰色决策模型计算,最终确定B25时,喷油提前角由25°CA再推迟4°CA喷油,与原机相比,以牺牲小部分动力性为代价,大幅改善其排放性,NOx与Soot排放均优于原机,柴油机综合性能最优,STC柴油机最佳喷油提前角为21°CA。