基于深度学习的微藻自动检测系统研究

目的 微藻养殖产业规模巨大,在养殖过程中微藻易受杂菌和其他污染物的影响,因此需要定期对微藻进行检测,以确定其生长情况。现有的光学显微成像法和光谱分析法对实验人员、实验设备及场地的要求较高,无法做到实时快速检测。为了实现实时快速检测,需要一套检测要求低、速度快的实时微藻检测系统。方法 本文开发了一种基于深度学习的微藻检测系统,通过搭建一套基于明场成像的显微成像设备,使用采集的图像训练基于YOLOv3的神经网络,并将训练好的神经网络部署到微型计算机,从而实现了实时便携微藻检测。本文对特征提取网络进行改进,包括引入跨区域残差连接机制和注意力选择机制,另外还将优化器改为Adam优化器,使用多阶段多方法组合策略。结果 加载跨区域残差连接机制时最高平均精度（mAP）值为0.92。通过与人工结果进行对比,得到检测误差为2.47%。结论 该系统能够实现微藻实时便携检测,提供较为准确的检测结果,可以应用于微藻养殖中的定期检测。     

A Novel Wearable Real-Time Sleep Apnea Detection System Based on the Acceleration Sensor

Background and objectiveThe apnea syndrome is characterized by an abnormal breath pause or reduction in the airflow during sleep. It is reported in the literature that, it affects 2% of middle-aged women and 4% of middle-aged men, approximately. This study has vital importance, especially for the elderly, the disabled, and pediatric sleep apnea patients.MethodsIn this study, a device is developed to detect apnea events to alert the patient. The device records continuously accelerations on the diaphragm by using an acceleration sensor, which is placed on the patient's diaphragm. When the apnea is detected by the accelerometer-based system, a signal is sent to the wristband, and then the vibration motor on the wristband vibrates until the patient starts breathing again. The force of the vibration motor can be adjusted according to the patients' sleep debt, especially for elderly, disabled, or pediatric patients. There is no need for a sleeping room to see the patients' breathing properties since those parameters can be stored by using the developed device on a secure digital memory card (SD) at patients' homes during sleeping.ResultsA study group were formed of 10 patients (4 males (40%) and 6 females (60%)) with different characteristics ([mean] age, 36.3; height, 169.6 cm; and body weight, 81.4 kg). The patients in the study group have sleep apnea (SA). All the apnea events were detected, and all the patients were successfully alerted. Also, the lying position, which is a significant issue, is performed in this study.ConclusionsThis work proposed using an acceleration sensor as a reliable method of sleep apnea screening, detection of an apnea event, sending alert to the patient, and detection of the patient lying position. The developed device is more economical, comfortable, and convenient than existing systems for not only the patients but also the doctors. The patients can easily use this device in their home environment.     

Sensitivity of the IQM and MatriXX detectors in megavolt photon beams

AimThis study focused on evaluating the sensitivity of integral quality monitoring (IQM^®) system and MatriXX detectors. These two detectors are recommended for radiotherapy pre-treatment quality assurance (QA).BackgroundIQM is a large wedged-shaped ionisation chamber mounted to the linear accelerator (linac) head in practice. MatriXX consists of an array of ionisation chambers also attached to the linac head.Materials and methodsIn this study, the dosimetric performance and sensitivity of MatriXX and IQM detectors were evaluated using the following characteristics: reproducibility, linearity, error detection capability and three-dimensional conformal radiotherapy (3D-CRT) plans of the head and neck, thorax and pelvic regions.ResultsThis study indicates that the signal responses of the large ionisation chamber device (IQM) and the small pixel array of ionisation chambers device (MatriXX) are reproducible, linear and sensitive to MLC positional errors, backup jaw positional errors and dose errors. The local percentage differences for dose errors of 1%, 2%, and 3% were, respectively, within 0.35–8.23%, 0.78–16.21%, and 1.10–24.41% for the IQM device. While for the MatriXX detector, the ranges were between 0.24–3.19, 0.57–6.43 and 0.81–12.95, respectively. Since IQM is essentially a double wedge-shaped large ionisation chamber, its reproducibility and detection capability are competitive to that of MatriXX. In addition, the sensitivity of the two QA systems increases with an increase in escalation percentage, and the signal responses are patient plan specific.ConclusionsThe two detectors response signals have good correlations and they are accurate for pre-treatment QA. Statistically, (P < 0.05) there is a significant difference between the IQM and MatriXX response to dose errors.     

A mobile one-lead ECG device incorporated in a symptom-driven remote arrhythmia monitoring program. The first 5,982 Hartwacht ECGs

Background

In recent years many mobile devices able to record health-related data in ambulatory patients have emerged. However, well-organised programs to incorporate these devices are sparse. Hartwacht Arrhythmia (HA) is such a program, focusing on remote arrhythmia detection using the AliveCor Kardia Mobile (KM) and its algorithm.

Objectives

The aim of this study was to assess the benefit of the KM device and its algorithm in detecting cardiac arrhythmias in a real-world cohort of ambulatory patients.

Methods

All KM ECGs recorded in the HA program between January 2017 and March 2018 were included. Classification by the KM algorithm was compared with that of the Hartwacht team led by a cardiologist. Statistical analyses were performed with respect to detection of sinus rhythm (SR), atrial fibrillation (AF) and other arrhythmias.

Results

5,982 KM ECGs were received from 233 patients (mean age 58 years, 52% male). The KM algorithm categorised 59% as SR, 22% as possible AF, 17% as unclassified and 2% as unreadable. According to the Hartwacht team, 498 (8%) ECGs were uninterpretable. Negative predictive value for detection of AF was 98%. However, positive predictive value as well as detection of other arrhythmias was poor. In 81% of the unclassified ECGs, the Hartwacht team was able to provide a diagnosis.

Conclusions

This study reports on the first symptom-driven remote arrhythmia monitoring program in the Netherlands. Less than 10% of the ECGs were uninterpretable. However, the current performance of the KM algorithm makes the device inadequate as a stand-alone application, supporting the need for manual ECG analysis in HA and similar programs.

     

Device Attitude and Real-Time 3D Visualization: An Interface for Elderly Care

Objectivethis paper presents an innovative graphical user interface to visualize the attitude of a sensing device in a three-dimensional space, serving a wide-range of medical applications.Material and methodsbased on inertial measurement units (IMU) or on magnetic, angular rate and gravity (MARG) sensors, a processing unit provides Euler angles using a sensor fusion technique to display the orientation of the device relative to the Earth frame in real-time. The device is schematized by linking six polygonal regions, and is subject to sequential rotations by updating the graph each 350 ms. We conduct comparative studies between the two sensing devices, i.e. IMUs and MARGs, as well as two orientation filters, namely Madgwick's algorithm and Mahony's algorithm.Resultsthe accuracy of the system is reported as a function of (i) the sampling frequency, (ii) the sensing unit, and (iii) the orientation filter, following two elderly care applications, namely fall risk assessment and body posture monitoring. The experiments are conducted using public datasets. The corresponding results show that Madgwick's algorithm is best suited for low sampling rates, whereas MARG sensors are best suited for the detection of postural transitions.Conclusionthis paper addresses the different aspects and discusses the limitations of attitude estimation systems, which are important tools to help clinicians in their diagnosis.     

Development of an Immunochromatographic Test for Diagnosis of Visceral Leishmaniasis Based on Detection of a Circulating Antigen

BackgroundVisceral leishmaniasis (VL) is a life-threatening disease caused by protozoan parasites of the Leishmania donovani complex. Early case detection followed by adequate treatment is essential to the control of VL. However, the available diagnostic tests are either invasive and require considerable expertise (parasitological demonstration of the parasite in tissue smears) or unable to distinguish between past and active infection (serological methods). Therefore, we aimed to develop a lateral flow assay in the form of an immunochromatographic test (ICT) device based on the detection of a circulating Leishmania antigen using monoclonal antibodies (mAbs).Conclusion/SignificanceThe newly developed ICT is an easy to use and more accurate diagnostic tool which fulfils the performance and operational characteristics required for VL case detection under field and laboratory conditions. As our ICT detects a circulating antigen, it will also be useful in monitoring treatment success and diagnosing VL in immunocompromised patients.     

Transcatheter aortic valve replacement: impact of pre-procedural FEops HEARTguide assessment on device size selection in borderline annulus size cases

ObjectivesThe aim of this study is to evaluate device size selection in patients within the borderline annulus size range undergoing transcatheter aortic valve replacement (TAVR) and to assess if pre-procedural patient-specific computer simulation will lead to the selection of a different device size than standard of care.BackgroundIn TAVR, appropriate device sizing is imperative. In borderline annulus size cases no standardised technique for tailored device size selection is currently available. Pre-procedural patient-specific computer simulation can be used, predicting the risk for paravalvular leakage (PVL) and need for permanent pacemaker implantation (PPI).MethodsIn this multicentre retrospective study, 140 patients in the borderline annulus size range were included. Hereafter, device size selection was left to the discretion of the operator. After TAVR, in 24 of the 140 patients, patient-specific computer simulation calculated the most appropriate device size expected to give the lowest risk for PVL and need for PPI. In these 24 patients, device size selection based on patient-specific computer simulation was compared with standard-of-care device size selection relying on a standardised matrix (Medtronic).ResultsIn a significant proportion of the 140 patients (26.4%) a different device size than recommended by the matrix was implanted. In 10 of the 24 patients (41.7%) in whom a computer simulation was performed, a different device size was recommended than by means of the matrix.ConclusionsDevice size selection in patients within the borderline annulus size range is still ambiguous. In these patients, patient-specific computer simulation is feasible and can contribute to a more tailored device size selection.     

Assessment of the MANTA closure device in transfemoral transcatheter aortic valve replacement: a single-centre observational study

Objectives

The present study aims to evaluate the efficacy and safety of the MANTA vascular closure device (VCD) (Teleflex, Morrisville, NC, USA) in transfemoral transcatheter aortic valve replacement (TF-TAVR).

Background

To close the femoral artery in TF-TAVR a VCD is the treatment of choice. Data involving suture-based VCDs have been extensive. Although scarce, results on the MANTA device are promising. There is no consensus yet as to whether the MANTA device is associated with fewer access-site-related vascular/bleeding complications when compared to suture-based VCDs.

Methods

In this prospective single-arm study, performed at a single centre, a total of 73 patients eligible for TF-TAVR were included and consecutively treated with the MANTA device.

Results

Access-site-related vascular complications were seen in 13.7% of patients treated with the MANTA device. In this group of patients only minor vascular complications were observed. Access-site-related bleeding complications were rare (6.8%), and device failure was seen in 13.7% of the patients.

Conclusions

This single-centre study confirms that use of the MANTA device in TF-TAVR is feasible with an acceptable rate of access-site-related complications and no major vascular complications.

     

Affordable artificial intelligence-based digital pathology for neglected tropical diseases: A proof-of-concept for the detection of soil-transmitted helminths and Schistosoma mansoni eggs in Kato-Katz stool thick smears

BackgroundWith the World Health Organization’s (WHO) publication of the 2021–2030 neglected tropical diseases (NTDs) roadmap, the current gap in global diagnostics became painfully apparent. Improving existing diagnostic standards with state-of-the-art technology and artificial intelligence has the potential to close this gap.Methodology/Principal findingsWe prototyped an artificial intelligence-based digital pathology (AI-DP) device to explore automated scanning and detection of helminth eggs in stool prepared with the Kato-Katz (KK) technique, the current diagnostic standard for diagnosing soil-transmitted helminths (STHs; Ascaris lumbricoides, Trichuris trichiura and hookworms) and Schistosoma mansoni (SCH) infections. First, we embedded a prototype whole slide imaging scanner into field studies in Cambodia, Ethiopia, Kenya and Tanzania. With the scanner, over 300 KK stool thick smears were scanned, resulting in total of 7,780 field-of-view (FOV) images containing 16,990 annotated helminth eggs (Ascaris: 8,600; Trichuris: 4,083; hookworms: 3,623; SCH: 684). Around 90% of the annotated eggs were used to train a deep learning-based object detection model. From an unseen test set of 752 FOV images containing 1,671 manually verified STH and SCH eggs (the remaining 10% of annotated eggs), our trained object detection model extracted and classified helminth eggs from co-infected FOV images in KK stool thick smears, achieving a weighted average precision (± standard deviation) of 94.9% ± 0.8% and a weighted average recall of 96.1% ± 2.1% across all four helminth egg species.Conclusions/SignificanceWe present a proof-of-concept for an AI-DP device for automated scanning and detection of helminth eggs in KK stool thick smears. We identified obstacles that need to be addressed before the diagnostic performance can be evaluated against the target product profiles for both STH and SCH. Given that these obstacles are primarily associated with the required hardware and scanning methodology, opposed to the feasibility of AI-based results, we are hopeful that this research can support the 2030 NTDs road map and eventually other poverty-related diseases for which microscopy is the diagnostic standard.     

Bacteria as sensors: Real-time NMR analysis of extracellular metabolites detects sub-lethal amounts of bactericidal molecules released from functionalized materials

BackgroundCells exposed to stress factors experience time-dependent variations of metabolite concentration, acting as reliable sensors of the effective concentration of drugs in solution. NMR can detect and quantify changes in metabolite concentration, thus providing an indirect estimate of drug concentration. The quantification of bactericidal molecules released from antimicrobial-treated biomedical materials is crucial to determine their biocompatibility and the potential onset of drug resistance.MethodsReal-time NMR measurements of extracellular metabolites produced by bacteria grown in the presence of known concentrations of an antibacterial molecule (irgasan) are employed to quantify the bactericidal molecule released from antimicrobial-treated biomedical devices. Viability tests assess their activity against E. coli and S. aureus planktonic and sessile cells. AFM and contact angle measurements assisted in the determination of the mechanism of antibacterial action.ResultsNMR-derived concentration kinetics of metabolites produced by bacteria grown in contact with functionalized materials allows for indirectly evaluating the effective concentration of toxic substances released from the device, lowering the detection limit to the nanomolar range. NMR, AFM and contact angle measurements support a surface-killing mechanism of action against bacteria.ConclusionsThe NMR based approach provides a reliable tool to estimate bactericidal molecule release from antimicrobial materials.General significanceThe novelty of the proposed NMR-based strategy is that it i) exploits bacteria as sensors of the presence of bactericidal molecules in solution; ii) is independent of the chemo-physical properties of the analyte; iii) establishes the detection limit to nanomolar concentrations.     

Response of the ArcCHECK® device at 6 MV and 15 MV for VMAT and IMRT quality control

PurposeTo study the response of the ArcCHECK® device as VMAT and IMRT verification system.MethodsVarious tests analyzing the linearity, the repeatability and the angular dependence of the device response, its dependence with the pulse repetition rate and the leakage losses were performed. The long-term response in dose measurements and the uniformity of the detectors conforming the system were controlled using a statistical process control program. The Elekta Infinity™ 6 and 15 MV photon beams were used.ResultsThe device showed excellent repeatability and linearity. The differences between the responses obtained for any pair of angular incidences were less than 2%. The absorbed dose increased by 3% when the pulse repetition rate varied from 50 to 600 MU/min. Results are in overall agreement with those found in previous works for the ArcCHECK®, in which a reduced number of the device diodes were analyzed, and for the MapCheck®, an older 2D device that used the same diodes. Charge losses were found to be negligible except for some of the diodes of the device. The statistical process control program is a very useful tool to control the correct functioning of the device in the long term.ConclusionsThe results of the analysis carried out indicate that the working and stability conditions of the ArcCHECK® device are adequate for its purpose. The dependence with the pulse repetition rate should be considered when VMAT or similar treatments are evaluated. A control program for the statistical monitoring of the device would be desirable and useful.     

Development of a reliable low-cost controlled cooling rate instrument for the cryopreservation of hematopoietic stem cells

Background aimsAn optimal cooling rate is one of the critical factors influencing the survival of cells during cryopreservation. We describe a novel device, called the box-in-box, that has been developed for optimal cryopreservation of human hematopoietic stem cells (HSC).MethodsThis work presents the design of the device, a mathematical formulation describing the expected temperature histories of samples during the freezing process, along with actual experimental results of thermal profile tests. In experiments, when the box-in-box device was transferred from room temperature to a ?80°C freezer, a cooling rate of ?1 to ?3.5°C/min, which has been widely used for the cryopreservation of HSC, was achieved. In order to evaluate this device further, HSC cryopreservation was compared between the box-in-box device and a commercially available controlled-rate freezer (CryoMed).ResultsThe experimental data, including total cell population and CD34⁺ hematopoietic progenitor cell recovery rates, viability and cell culture colony assays, showed that the box-in-box worked as well as the CryoMed instrument. There was no significant difference in either survival rate or the culture/colony outcome between the two devices.ConclusionsThe box-in-box device can work as a cheap, durable, reliable and maintenance-free instrument for the cryopreservation of HSC. This concept of a box-in-box may also be adapted to other cooling rates to support cryopreservation of a wide variety of tissues and cells.     

Predicting therapy response in live tumor cells isolated with the flexible micro spring array device

Cells disseminated from primary epithelial tumors into peripheral blood, called circulating tumor cells (CTCs), can be monitored to assess metastases and to provide a surrogate marker of treatment response. Here, we demonstrate how the flexible micro spring array (FMSA) device—a novel microfluidic device that enriches CTCs by two physical parameters: size and deformability—could be used in the rational development of treatment intervention and as a method to study the fundamental biology of CTCs. Cancer cells of different origins were spiked into healthy samples of donor blood to mimic blood samples of metastatic cancer patients. This spiked human blood was filtered using the FMSA device, and the recovered cells were successfully expanded in vitro and in a novel in vivo system. A series of experiments were performed to characterize these cells and to investigate the effect of chemotherapy on the resulting cultures. As few as 20 colon cancer cells in 7.5 mL blood could be isolated with the FMSA device, expanded both in vitro and in vivo and used at 25 cells per well to obtain significant and reliable chemosensitivity data. We also show that isolating a low number of viable patient CTCs and maintaining them in culture for a few weeks is possible. The isolation of viable cancer cells from human blood using the FMSA device provides a novel and realistic means for studying the biology of viable CTCs and for testing drug efficacy on these rare cells—a hypothesis that can be tested in future clinical trials.     

Dosimetric characterization of a novel 90Y source for use in the conformal superficial brachytherapy device

PurposeTo characterize the dose distribution in water of a novel beta-emitting brachytherapy source for use in a Conformal Superficial Brachytherapy (CSBT) device.Methods and materialsYttrium-90 (⁹⁰Y) sources were designed for use with a uniquely designed CSBT device. Depth dose and planar dose measurements were performed for bare sources and sources housed within a 3D printed source holder. Monte Carlo simulated dose rate distributions were compared to film-based measurements. Gamma analysis was performed to compare simulated and measured dose rates from seven ⁹⁰Y sources placed simultaneously using the CSBT device.ResultsThe film-based maximum measured surface dose rate for a bare source in contact with the surface was 3.35 × 10^–7 cGy s⁻¹ Bq⁻¹. When placed in the source holder, the maximum measured dose rate was 1.41 × 10^–7 cGy s⁻¹ Bq⁻¹. The Monte Carlo simulated depth dose rates were within 10% or 0.02 cm of the measured dose rates for each depth of measurement. The maximum film surface dose rate measured using a seven-source configuration within the CSBT device was 1.78 × 10⁻⁷ cGy s⁻¹ Bq⁻¹. Measured and simulated dose rate distribution of the seven-source configuration were compared by gamma analysis and yielded a passing rate of 94.08%. The gamma criteria were 3% for dose-difference and 0.07056 cm for distance-to-agreement. The estimated measured dose rate uncertainty was 5.34%.Conclusions⁹⁰Y is a unique source that can be optimally designed for a customized CSBT device. The rapid dose falloff provided a high dose gradient, ideal for treatment of superficial lesions. The dose rate uncertainty of the ⁹⁰Y-based CSBT device was within acceptable brachytherapy standards and warrants further investigation.     

研究报告: 基于核酸适配体的胶体金比色法检测鳗弧菌

目的 鳗弧菌（Vibrio anguillarum）可引起鲑鱼、鳗鲡、鲈鱼和牙鲆等多种水产养殖动物的疾病，是水产养殖中的一种重要病原菌，对其进行快速检测是确保水产养殖安全和食品安全所必需的。方法 本文利用鳗弧菌与其核酸适配体之间较强的亲和力，通过鳗弧菌夺取胶体金颗粒表面的核酸适配体，使胶体金溶液的吸光度发生变化，从而建立一种可定量检测鳗弧菌的方法。结果 该方法对鳗弧菌的吸光度值显著高于对溶藻弧菌、铜绿假单胞菌、变形假单胞菌、嗜水气单胞菌和迟钝爱德华氏菌等非目标菌的吸光度值（P<0.01），并在1~10⁵ CFU/ml的检测范围内呈现较好的线性关系。用该方法对不同盐度和鱼体组织样品进行加标回收检测，结果显示回收率和相对标准偏差等指标都符合相应检测标准。结论 该检测方法对鳗弧菌有较好的特异性，可用于水产品或食品中鳗弧菌的定量检测。     

Improved isolation and expansion of bone marrow mesenchymal stromal cells using a novel marrow filter device

Background aimsMesenchymal stromal cells (MSCs) have been studied as cell therapy to treat a vast array of diseases. In clinical MSC production, the isolated cells must undergo extensive ex vivo expansion to obtain a sufficient dose of MSCs for the investigational treatment. However, extended tissue culture is fraught with potential hazards, including contamination and malignant transformation. Changes of gene expression with prolonged culture may alter the therapeutic potential of the cells. Increasing the recovery of MSCs from the freshly harvested bone marrow allowing for less ex vivo expansion would represent a major advance in MSC therapy.MethodsHuman bone marrow cells from eight healthy donors were processed using a marrow filter device and, in parallel, using buoyant density centrifugation by two independent investigators. The initial nucleated cell recovery and the final yield, immunophenotype and trilineage differentiation potential of second-passage MSCs were examined.ResultsThe marrow filter device generated significantly greater initial cell recovery requiring less investigator time and resulted in approximately 2.5-fold more MSCs after the second passage. The immunophenotype and differentiation potential of MSCs isolated using the two methods were equivalent and consistent with the defining criteria. The two independent investigators generated comparable results.ConclusionsThis novel filter device is a fast, efficient and reliable system to isolate MSCs and should greatly expedite pre-clinical and clinical investigations of MSC therapy.     

Patient Preferences Regarding Device Reuse and Potential of Devices for Reuse - A Study in a Veteran Population

BackgroundMany cardiac patients need and undergo device implants. Veterans’ preferences regarding post-mortem handling of devices are not known. Cardiac patients in low- and middle-income countries who need but cannot afford devices rely on donations. Charitable organizations have successfully provided devices for reuse to such patients.ObjectiveWe estimated the number of devices with potential for possible reuse in a veteran population.MethodsBetween January and December 2008, at a tertiary medical center, veterans with implanted cardiac devices were surveyed using a questionnaire for their preferences regarding post-mortem handling. One choice was donation to charity for reuse. Although altruistic, it is unclear what percent of such devices have reuse potential. Retrospective chart review of veterans who underwent device implants between 1992 and 2007 identified a cohort of patients with Implantable Cardiac Defibrillators (ICDs) who had died by April 31st 2009. In this cohort, ICDs implanted in the year preceding the patient’s death were counted as having reuse potential.Results94 of 97 veterans completed the survey. 56% were unaware of how devices are handled after death. The top three preferences for postmortem handling were: return to manufacturer, return to hospital and donation for reuse. 88% were willing to sign an advance device directive. Retrospective review identified 161 veterans who had received 301 ICDs. Of these, 77 ICDs (25%) had median reuse potential of 3.1 years.ConclusionIn a VA cohort of deceased patients a substantial proportion of devices had reuse potential. Further research is needed to direct health policy.     

A Double-Needle Gold-Silver Electrodes Continuous Glucose Monitoring Device

ObjectivesDiabetes is a serious, long-term disease and the use of continuous glucose monitoring sensors can reduce reliance on other painful invasive blood testing methods such as the finger blood glucose test. According to our work, a low-cost continuous glucose sensor has been developed based on electrochemical measurement techniques.MaterialsThe sensor is based on a two needles system; a gold and a silver electrode are integrated into a circular shaped electronic printed circuit board (PCB). The sensing part is based on biological electrochemical measurements. Glucose oxidase (Gox) was used as the active sensing element and ferrocene (Fc) as a mediator. Simple and low-cost coating methods were used; these methods are self-assembled monolayers and deep coating. This will reduce the final cost of the sensor as no expensive technique was used. The electrical subsystem contains a low-noise and low-power trans-impedance front-end as well as a single-chip low-power Bluetooth microcontroller with a 12-bit Analog-to-Digital Converter (ADC).ResultsThe sensor was tested in various concentrations of glucose. As a result of initial in vitro experiments, detailed analytical performance metrics are presented. The device has consistently shown a sensitivity of 3.059 mV/(mg/dl) reading with a linear range of 0-400 mg/dl.ConclusionThe proposed study shows promising results for glucose detection. Thus, this type of sensor can be used for different analyzes targeting biological applications after further investigations and analysis.     

基于磁驱动技术的空肠营养管的设计

目的:为解决目前床旁鼻肠管快速置入成功率低这一临床难题,该文提出一种基于磁驱动技术的空肠营养管的设计。方法:分析了现有空肠营养管置管过程中的动力因素,结合磁驱动技术原理,提出了通过体外旋转磁场带动体内感应磁体螺旋式前进的设计方案,以期缩短空肠营养管的飘管时间。结果:该设计包括磁性空肠营养管和体外磁力驱动装置两部分。其中磁性空肠营养管由管体和感应磁头两部分构成,感应磁头包括磁体内核和硅胶外壳。磁力驱动装置由多极磁体和手持式微型电机组成。操作时通过体外磁力驱动装置发出大旋转磁场带动空肠营养管的感应磁头做轴向旋转运动,可加速空肠营养管在肠道内的移动,达到缩短飘管时间的目的。结论:该设计基于磁驱动技术原理,设计巧妙,符合磁力学原理,操作简单,具有临床应用潜力。     

RNA polymerase mutant with altered sigma factor in Escherichia coli.

Summary E. gracilis chloroplast DNA Bam fragments E and D, coding for rRNA were cloned separately using the plasmid pBR 322 as vector and E. coli as host. The newly constructed recombinant plasmids EgcKS 8 and EgcKS 11 (containing the Bam HI fragments E and D respectively) were analysed and characterized by gel electrophoresis, electronmicroscopy and analytical ultracentrifugation.Abbreviations Ap Ampicillin - Tc Tetracycline-hydrochloride - Bam HI endonuclease isolated from Bacillus amyloliquefaciens - Eco RI endonuclease isolated from E. coli RY13 - Bgl II endonuclease isolated from Bacillus globiggi - EDTA Ethylene-diamine-tetra-acetic-acid - ctDNA chloroplast DNA An abstract of this work was presented at the 10th annual meeting of the Union Schweizerischer Gesellschaften für Experimentelle Biologie, Davos 19th and 20th Mai, 1978. The recommendations of the Schweizerische Akademie für medizinische Wissenschaften for work with recombinant DNA-molecules were respected throughout this work.