Determination of olaquindox,carbadox and cyadox in animal feeds by ultra-performance liquid chromatography tandem mass spectrometry

Olaquindox, carbadox, and cyadox are chemically synthesised antibacterial and growth-promoting agents for animals. At high doses they may exert mutagenicity and hepatic and adrenal toxicities in animals. Regrettably, these substances are frequently abused or misused when added into animal feeds. Thus, developing a sensitive and reliable method for simultaneous determination of olaquindox, carbadox, and cyadox in different kinds of animal feeds is crucially important for food safety monitoring. In this paper we optimised instrumental conditions, extraction solvents, solid phase extraction cartridges, and pH of the loading solvents on the Oasis HLB cartridge. Under the optimal conditions, mean recoveries ranged from 74.1 to 111%, and intra-day and inter-day variations were lower than 14.6% and 10.8%, respectively. The limits of quantification for olaquindox, carbadox, and cyadox were 0.05 mg kg^?1, 0.10 mg kg^?1, and 0.025 mg kg^?1, respectively. The proposed method uses ultra-performance liquid chromatography tandem mass spectrometry and is sensitive and reliable for the simultaneous determination of olaquindox, carbadox, and cyadox in three kinds of animal feeds (specifically, mixed feed, concentrated feed, and additive premixed feed). This method has good precision, high sensitivity, and good reproducibility, and thus it can be used for convenient and accurate determination of olaquindox, carbadox, and cyadox in different kinds of animal feeds.     

Modeling and design of 3-D MPPT for ultra low power RF energy harvesters

Radio-Frequency (RF) energy harvesting must cope with the limited availability and high variability of the energy source. In this paper, the modeling of an RF harvester for ultra low power environments is presented. A mathematical model based on theoretical analysis is developed. The model demonstrates that the maximum transferred power point is located in a three-dimensional space defined by the input capacitance, the output voltage, and the load resistance of the rectifier circuit. Moreover, the mathematical model returns results in substantial agreement with the SPICE simulation results, while guaranteeing a remarkable reduction of the required computation time. Furthermore, the paper reports the implementation of a mixed signal system for the 3-D MPPT, to be embedded in an RF harvester, in a 65 nm CMOS technology. The circuit exhibits a simulated power consumption lower than 100 nW, making this solution suitable for ultra low power harvesting.     

超高效液相色谱-串联质谱法同时检测糕点中6种甜味剂

目的建立超高效液相色谱-串联质谱法同时测定糕点中6种常用合成甜味剂的分析方法。方法选用超纯水作为提取溶剂,涡旋和超声提取后,低温离心,取部分上清液加入正己烷除脂,Waters Atlantis■T3色谱柱、甲醇-5 mmol/L甲酸铵(含0.1%甲酸)作为流动相、亲水亲脂平衡型固相萃取柱HLB(hydrophile-lipophile balance)净化。结果6种甜味剂在质量浓度为10~200 ng/mL的曲线范围内呈良好线性关系,相关系数r均大于0.999,平均加标回收率在85.0%-98.2%之间,相对平均偏差(relative standard deviation,RSD)为1.3%~6.7%。结论该方法具有前处理简单、灵敏度高、检测速度快等优点,适合糖精钠、甜蜜素、三氯蔗糖、阿斯巴甜、阿力甜、纽甜的检测,但不适用于安赛蜜的检测。     

Effects of Ti,Y, and Hf additions on the thermal properties of ZrB2

Reactive hot pressing was utilized to synthesize and densify four ZrB₂ ceramics with impurity contents low enough to avoid obscuring the effects of dopants on thermal properties. Nominally pure ZrB₂ had a thermal conductivity of 141 ± 3 W/m K at 25 °C. Additions of 3 at% of Ti, Y, or Hf decreased the thermal conductivity by 20 %, 30 %, and 40 %, respectively. The thermal conductivity of (Zr,Hf)B₂ was similar to ZrB₂ synthesized from commercial powders containing the natural abundance of Hf as an impurity. This is the first study to demonstrate that Ti and Y additions decrease the thermal conductivity of ZrB₂ ceramics and report intrinsic values for thermal conductivity and electrical resistivity of ZrB₂ containing transition metal additions. Previous studies were unable to detect these effects because the natural abundance of Hf present masked the effects of these additions.     

Transformation of metallic polymer precursor into nanosized HfTaC2 ceramics

Polymeric precursor for HfTaC₂ ceramic was prepared by coordination reaction between metal alkoxides and acetylacetone, subsequent hydrolysis, and blend with oligomeric novolac carbon sources. The phase analysis and microstructure study were conducted using X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). It showed that after pyrolyzed at 1450 °C for 90 min, HfTaC₂ was obtained with particle size ~50 nm and uniform elemental distribution. Phase transition from precursor to ceramic was studied by in situ XRD measurements at temperatures from 800 to 1200 °C. In the early stage, oxide solid solution Hf₆Ta₂O₁₇ was firstly detected at ~950 °C, followed by Ta₂O₅ and TaO. As temperature was raised, signals for TaO and Hf₆Ta₂O₁₇ gradually weakened and disappeared, while those for other phases strongly strengthened. Furthermore, formation of Hf_xTa_yC_z solid solution was monitored and confirmed by peak migration during 1300 °C isothermal treatment. When the sample was pyrolyzed at 1450 °C, solid solution Hf_xTa_yC_z was detected at different holding time. Phase structure at 90 min was the closest to standard HfTaC₂ with particle size D_v (90) ~ 200 nm.     

Preparation of porous ultra low k films using different sacrificial porogen precursors for 28 nM technological node

In order to reduce resistance capacitance (RC) delay and crosstalk between adjacent interconnect lines, the porous ultra low k (PULK) film with dielectric constant value ranging from 2.4 to 2.6 was introduced to be used as an insulator of the Cu integration in back end of the line (BEOL) for 28 nm technological node. In this paper, the PULK films were deposited by plasma enhanced chemical vapor deposition (PECVD) using two different sacrificial organic porogen precursors of bicycloheptadiene (BCHD) and alpha-terpinene (ATRP), and then the above co-deposited films were expose to UV radialization for removing sacrificial organic porogens to create pores. The effects of the different sacrificial organic porogen on the PULK film properties such as the dielectric constant, pore and porosity, k shift, mechanic strength, and RC were studied in detail. Results indicated that the hardness and modulus of the PULK film for the BCHD and ATRP precursors were 0.7 and 5.1 GPa and 1.0 and 7.1 Gpa, and their pore radiuses and porosities were 1.18 nm and 25% and 0.95 nm and 23%. The dielectric constant value of the PULK film for the BCHD and ATRP precursors were measured as 2.48 and 2.59 with Hg probe. The adhesion test indicated that the interfacial strength of the PULK film for the ATRP precursor was higher than that of the PULK film for the BCHD precursor. By the RC examination, it was seen that RC curve of the PULK film for the ATRP precursor was located below the curve of the PULK film for the BCHD precursor.     

专用聚丙烯树脂PPH-Y35生产及应用研究

针对无纺布的应用特性,对专用聚丙烯树脂PPH-Y35生产工艺、性能进行了优化。利用专用生产聚丙烯树脂PPH-Y35装置,用高效催化剂氢调法、选取复合抗氧化剂生产出高质量的产品。将用PPH-Y35生产的无纺布与同类产品的性能对比,其性能优异,在医疗卫生领域中的应用更有优势。     

Chirping techniques for enhancing the performance of SOA-based UWB over fiber systems: An experimental demonstration

A phaser-based processing technique was adopted in an UWB over fiber system employing SOA. The target is to simultaneously reduce the ASE noise impact and nonlinear effects inherent to optical amplification. Experimental results prove the effectiveness of chirping in terms of cross correlation and bit error rate.     

A computational and experimental study of ultra fine water mist as a total flooding agent

Computational fluid dynamics (CFD) calculations were carried out to design total flooding fire tests in a 28 m³ compartment for an ultra fine water mist (<10 μm). The exit momentum of the mist produced by a proprietary ultrasonic generator technology was extremely low with a mist discharge velocity below 1 m/s. The mist was discharged with multiple floor outlets equally spaced around the centrally located 120 kW pool-like gas fire. The transport of mist and its interaction with the fire was simulated by Fluent, a commercial CFD model. Lagrangian Discrete Phase Model (DPM) was used for droplets. Simulation predicted extinguishment within 10 s with a mist delivery rate of 1 l/min. However, in total flooding fire tests conducted, extinction times were more than 5 min. Additional computations approximating the ultra fine mist (UFM) as a dense gas agreed well with the observed transport timescales of minutes indicating that UFM behaves like a gas. Further, the mist–fire interaction needs a multi-phase Euler–Euler approach with a droplet vaporization model.     

Analytical evaluation of phenolic compounds and minerals of Opuntia robusta J.C. Wendl. and Opuntia ficus-barbarica A. Berger

In this study, 19 phenolic compounds were detected using high-throughput instrument ultra performance liquid chromatography with electrospray ionization tandem mass spectrometry (UPLC–ESI–MS/MS) in Opuntia ficus-barbarica A. Berger and Opuntia robusta J.C. Wendl. fruits. The five macro- and five micro-minerals determined in both species were analyzed using inductively coupled plasma–mass spectrometer. The phenolic compounds, mineral content, and the antioxidant capacity of the fruits of O. robusta and O. ficus-barbarica were analyzed. All phenolic compounds and minerals varied significantly between the two species. The total of phenolic compounds content was calculated as 69.237 and 66.385 mg kg^?1, respectively, in O. ficus-barbarica and O. robusta. Ferulic acid was the highest quantities, 31.620 and 26.931 mg kg^?1 in O. robusta and O. ficus-barbarica, in all phenolic contents, respectively. The macroelements calcium and potassium were the most abundant in both Opuntia species. The antioxidant activity of O. ficus-barbarica and O. robusta fruit samples was measured in the extracts of hexane, ethyl acetate, methanol, and water. The DPPH assay of Opuntia samples displayed a good radical scavenging inhibition, similar to butylated hydroxyanisole and butylated hydroxytoluene standards, as half maximal inhibitory concentration IC₅₀ = 69.32 and 67.57 μg mL^?1 in ethyl acetate extracts of O. ficus-barbarica and O. robusta fruits, respectively. This work presents a suitable method for the extraction, detection, and quantification of phenolic compounds by UPLC–ESI–MS/MS. MS/MS determination for multiclass determination was validated in Opuntia samples obtaining good results.

Abbreviations: ABTS, 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid; AChE, acetylcholinesterase; BChE, butyrylcholinesterase; BHA, butylated hydroxyanisole; BHT, butylated hydroxytoluene; DPPH, 2,2-diphenyl-1-picrylhydrazyl; DTNB, (5,50-Dithio-bis(2-nitrobenzoic)acid; ICP/MS, inductively coupled plasma/mass spectrometer; LoD, yhe limit of detection; MRM, multiple reaction monitoring; QEs, quercetin equivalents; PEs, pyrocatechol equivalents; R², correlation coefficients; r, Pearson’s correlation coefficient; SD, standard deviation; TIC, total ion chromatogram; UPLC–ESI–MS/MS, ultra performance liquid chromatography with electrospray ionization tandem mass spectrometry