Understanding chicken walks on n × n grid: Hamiltonian paths,discrete dynamics,and rectifiable paths

Understanding animal movements and modeling the routes they travel can be essential in studies of pathogen transmission dynamics. Pathogen biology is also of crucial importance, defining the manner in which infectious agents are transmitted. In this article, we investigate animal movement with relevance to pathogen transmission by physical rather than airborne contact, using the domestic chicken and its protozoan parasite Eimeria as an example. We have obtained a configuration for the maximum possible distance that a chicken can walk through straight and nonoverlapping paths (defined in this paper) on square grid graphs. We have obtained preliminary results for such walks which can be practically adopted and tested as a foundation to improve understanding of nonairborne pathogen transmission. Linking individual nonoverlapping walks within a grid‐delineated area can be used to support modeling of the frequently repetitive, overlapping walks characteristic of the domestic chicken, providing a framework to model fecal deposition and subsequent parasite dissemination by fecal/host contact. We also pose an open problem on multiple walks on finite grid graphs. These results grew from biological insights and have potential applications. © 2014 The Authors. Mathematical Methods in the Applied Sciences published by John Wiley & Sons Ltd.     

LC of sulfonamide residues in poultry muscle and eggs extracts using fluorescence pre‐column derivatization and monolithic silica column

A new, rapid, sensitive and selective HPLC method with fluorescence detection is described for the simultaneous determination of 12 sulfonamides, in the presence of putrescine as internal standard, after pre‐column derivatization with fluorescamine. The drugs were separated on a Chromolith Performance RP‐18 column (100×4.6 mm), using a gradient elution with a binary mobile phase of methanol/0.05 M acetate buffer (pH 3.4). Linearity of derivatization was obtained for concentrations from 3.0 to 300 μg/L in standard solutions. The whole procedure was evaluated and fully validated, according to the European Union Decision 2002/657/EC, for the determination of sulfonamides in turkey muscle and hen eggs following SPE. The LODs varied from 2 to 17 μg/kg in turkey and 2 to 15 μg/kg in egg samples. The average recoveries ranged between 96.9–108.6% in turkey muscle and 96.0–108.4% in egg samples, respectively.     

A novel droplet-tap sample-loading method for two-dimensional gel electrophoresis

A novel procedure, droplet-tap mode, has been devised for sample application for two-dimensional gel electrophoresis (2DE) expression profiles. The sample was loaded by evenly distributed tapping of droplets of the sample on to the rehydration buffer (RB) and then lowering the strip on to the solution surface. At normal loading concentrations, the number of spots obtained was increased by approximately one-third by this new approach compared with the rehydration loading procedure. The method also resulted in significantly improved resolution compared with cup loading when high concentrations of proteins were present, indicating its potential usefulness in micropreparative separation. In addition, recovery of the proteins confirmed that protein uptake was enhanced by use of this method. By enabling improved performances in 2DE, the proposed procedure has much potential for sample loading to meet the requirements of global proteome analysis.Electronic Supplementary Material Electronic Supplementary Material found in     

高效液相色谱法测定鸡组织与鸡蛋中氯苯胍的残留量

建立了测定鸡组织与鸡蛋中氯苯胍残留的高效液相色谱法。试样用乙腈提取,经HLB固相萃取柱净化和流动相定容后,采用高效液相色谱法测定。以乙腈-0.05 mol/L NH4H2PO4缓冲液(6:4, v/v, pH 6.5)为流动相,流速为1.0 mL/min,于317 nm波长下检测。氯苯胍在10～1000 μg/L范围内具有良好的线性关系;方法的检出限(信噪比为3)为10 μg/L,定量限(信噪比为10)为15 μg/kg;回收率为73.1%～88.7%。该法操作简便、快速、灵敏、准确,样品处理简便易行,适用于测定鸡组织与鸡蛋中残留的氯苯胍。     

High-performance liquid chromatographic determination/identification of oxytetracycline and sulphadimidine in meat and eggs

Summary A rapid method for the simultaneous determination/identification of residual oxytetracycline (OTC) and sulphadimidine (SDD) in meats (beef, pork, chicken) and eggs by high-performance liquid chromatography (HPLC) was developed. The extraction of OTC and SDD was performed using a Sep-Pak^? CN cartridge. The extracts contained OTC/SDD analytes when examined by HPLC using a LiChrospher^? 100 RP-8 end-capped column and a mobile phase of acetonitrile-acetic acid-water (28:4:68, v/v/v) with a photodiode array detector. The average recoveries from spiked samples (0.1 μg g⁻¹ and 1.0 μg g⁻¹) were in excess of 80.2% with coefficients of variation between 1.5 and 5.0%. The limits of detection for OTC and SDD were 0.05 and 0.02 μg g⁻¹, respectively.     

Bird Species Identification Using Spectrogram Based on Multi-Channel Fusion of DCNNs

Deep convolutional neural networks (DCNNs) have achieved breakthrough performance on bird species identification using a spectrogram of bird vocalization. Aiming at the imbalance of the bird vocalization dataset, a single feature identification model (SFIM) with residual blocks and modified, weighted, cross-entropy function was proposed. To further improve the identification accuracy, two multi-channel fusion methods were built with three SFIMs. One of these fused the outputs of the feature extraction parts of three SFIMs (feature fusion mode), the other fused the outputs of the classifiers of three SFIMs (result fusion mode). The SFIMs were trained with three different kinds of spectrograms, which were calculated through short-time Fourier transform, mel-frequency cepstrum transform and chirplet transform, respectively. To overcome the shortage of the huge number of trainable model parameters, transfer learning was used in the multi-channel models. Using our own vocalization dataset as a sample set, it is found that the result fusion mode model outperforms the other proposed models, the best mean average precision (MAP) reaches 0.914. Choosing three durations of spectrograms, 100 ms, 300 ms and 500 ms for comparison, the results reveal that the 300 ms duration is the best for our own dataset. The duration is suggested to be determined based on the duration distribution of bird syllables. As for the performance with the training dataset of BirdCLEF2019, the highest classification mean average precision (cmAP) reached 0.135, which means the proposed model has certain generalization ability.     

催化激光热透镜光谱法测定南阳恐龙蛋化石中痕量铱

催化激光热透镜光谱法测定南阳恐龙蛋化石中痕量铱阎宏涛,杨胜科（西北大学化学系,西安,７１００６９）关键词恐龙蛋化石,热透镜光谱法,催化反应,痕量铱的测定近年来,地质学界对白垩－第三纪界线（Ｋ－Ｔ界线）全球性铱的异常给予极大的关注［１］．化石中痕量铱的...     

超声波对丰年虫卵孵化的影响

研究了固定频率和强度的超声波对饵料生物丰年虫卵（ｃｈｉｒｏｃｅｐｈａｌｕｓ）化的影响。实验结果表明,在适宜的超声波辐照下,丰年虫卵的孵化率比对照组提高８％,孵化时间提前２ｈ。     

鸡蛋中三聚氰胺的液相色谱快速测定

建立了鸡蛋中三聚氰胺的液相色谱快速检测方法。样品经1%三氯乙酸溶液超声提取,磺基水杨酸和乙腈沉淀蛋白,高速离心分离,上清液过滤后直接由高效液相色谱分析。在优化的条件下,样品的色谱分析时间仅为10 min;三聚氰胺标准品在0.05～20 mg/L范围内,线性相关系数为0.9999;方法定量限为0.10 mg/kg (S/N＞10);1.0,2.0,4.0,6.0 mg/kg 4个加标水平测试,回收率在94.2%～107%之间;6次平行测试的相对标准偏差(RSD)为1.53%～2.06%。该方法前处理简单、分析速度快、灵敏度高,满足鸡蛋中三聚氰胺检验工作的快速测定要求。