The use of potassium iodide equilibrium density gradient centrifugation in the purification of RNA for hybridization with nonreiterated DNA sequences.

A new instrument has been developed that is able to monitor enzyme activities in chromatography column eluents automatically. The instrument consists of a simple stopped-flow instrument, equipped with a multishutoff valve to direct reagents and eluent flow. Assays of the eluate may be done at present intervals. The instrument may also be used for monitoring enzyme activities in perfasates as well as for monitoring the elution of metabolites.     

An instrument capable of imaging chlorophyll a fluorescence from intact leaves at very low irradiance and at cellular and subcellular levels of organization

An instrument capable of imaging chlorophyll a fluorescence, from intact leaves, and generating images of widely used fluorescence parameters is described. This instrument, which is based around a fluorescence microscope and a Peltier-cooled charge-coupled device (CCD) camera, differs from those described previously in two important ways. First, the instrument has a large dynamic range and is capable of generating images of chlorophyll a fluorescence at levels of incident irradiance as low as 0.1 μmol m^?2 s^?1. Secondly, chlorophyll fluorescence, and consequently photosynthetic performance, can be resolved down to the level of individual cells and chloroplasts. Control of the instrument, as well as image capture, manipulation, analysis and presentation, are executed through an integrated computer application, developed specifically for the task. Possible applications for this instrument include detection of early and differential responses to environmental stimuli, including various types of stress. Images illustrating the instrument's capabilities are presented.     

Controlled rate freezing of human marrow in a constant temperature cooling gradient in air

A new instrument which utilizes a computer controlled freezing platform moving in a constant air temperature gradient generated over liquid nitrogen (LN2) was evaluated for cryopreservation of human marrow. Marrows were placed horizontally on the freezing platform which was suspended over LN2 in a cylindrical freezing chamber. The platform was raised or lowered to maintain a predetermined fixed cooling rate in response to temperature monitored and recorded by the computer from a thermocouple placed at platform level. Separate freezing programs were created for different marrow volumes. The viability of normal marrow was tested in vitro before and after freezing. Recovery of marrow cells after freezing and thawing, as measured by cell counts and CFU-GM assays, were the same for the constant air gradient instrument as for a conventional freezing instrument. Thirteen patients received autologous marrow transplants utilizing marrow cryopreserved in the constant air gradient instrument and engraftment results were indistinguishable from those obtained for marrow cryopreserved with a conventional instrument.     

A Cost-Effective Solution for the Reliable Determination of Cell Numbers of Microorganisms in Liquid Culture

The concentration of microorganisms in growth medium is an important parameter in microbiological research. One of the approaches to determine this parameter is based on the physical interaction of small particles with light that results in light scattering. Table-top spectrophotometers can be used to determine the scattering properties of a sample as a change in light transmission. However, a portable, reliable, and maintenance-free instrument that can be built from inexpensive parts could provide new research opportunities. In this report, we show how to build such an instrument. This instrument consists of a low power monochromatic light-emitting diode, a monolithic photodiode, and a microcontroller. We demonstrate that this instrument facilitates the precise determination of cell concentrations for the bacteria Escherichia coli and Pseudomonas aeruginosa as well as the cyanobacterium Synechocystis sp. PCC 6803 and the green alga Chlamydomonas reinhardtii.     

Depth Profilometry via Multiplexed Optical High-Coherence Interferometry

Depth Profilometry involves the measurement of the depth profile of objects, and has significant potential for various industrial applications that benefit from non-destructive sub-surface profiling such as defect detection, corrosion assessment, and dental assessment to name a few. In this study, we investigate the feasibility of depth profilometry using an Multiplexed Optical High-coherence Interferometry MOHI instrument. The MOHI instrument utilizes the spatial coherence of a laser and the interferometric properties of light to probe the reflectivity as a function of depth of a sample. The axial and lateral resolutions, as well as imaging depth, are decoupled in the MOHI instrument. The MOHI instrument is capable of multiplexing interferometric measurements into 480 one-dimensional interferograms at a location on the sample and is built with axial and lateral resolutions of 40 μm at a maximum imaging depth of 700 μm. Preliminary results, where a piece of sand-blasted aluminum, an NBK7 glass piece, and an optical phantom were successfully probed using the MOHI instrument to produce depth profiles, demonstrate the feasibility of such an instrument for performing depth profilometry.     

A systematic review of instrumental variable analyses using geographic region as an instrument

BackgroundInstrumental variables analysis is a methodology to mitigate the effects of measured and unmeasured confounding in observational studies of treatment effects. Geographic area is increasingly used as an instrument.MethodsWe conducted a literature review to determine the properties of geographic area in studies of cancer treatments. We identified cancer studies performed in the United States which incorporated instrumental variable analysis with area-wide treatment rate within a geographic region as the instrument. We assessed the degree of treatment variability between geographic regions, assessed balance of measured confounders afforded by geographic area and compared the results of instrumental variable analysis to those of multivariable methods.ResultsGeographic region as an instrument was relatively common, with 22 eligible studies identified, many of which were published in high-impact journals. Treatment rates did not vary greatly by geographic region. Covariates were not balanced by the instrument in the majority of studies. Eight out of eleven studies found statistically significant effects of treatment on multivariable analysis but not for instrumental variables, with the central estimates of the instrumental variables analysis generally being closer to the null.ConclusionsWe recommend caution and an investigation of IV assumptions when considering the use of geographic region as an instrument in observational studies of cancer treatments. The value of geographic region as an instrument should be critically evaluated in other areas of medicine.     

2种不同器械扩锉后根管壁的细菌学研究

目的通过对临床病例的研究,比较减速镍钛机扩和普通不锈钢K型锉清洁根管的能力。方法选取临床需要根管治疗的患牙60例,随机分为2组,经开髓拨髓后分别用镍钛减速机扩和不锈钢K型及H型锉进行根管预备,预备完成后用灭菌棉捻擦拭管壁,作微生物检查。结果2组方法扩锉后对根管内微生物的变化做统计学分析,差异有显著性(P<0.05)。结论镍钛减速机扩对根管的清洁能力高于普通不锈钢扩锉,值得临床的推广。     

Flash fluorometer made from off-the-shelf photographic equipment to measure tissue levels of fluorescein

A device to measure fluorescein in tissue has been constructed from standard photographic equipment--an electronic strobe and a flashmeter both covered with interference filters. The instrument works well in the light and need not touch the area being measured, an advantage over existing fluorometers. The instrument has been used to measure the amount of dye in flaps in rats, pigs, and three humans. The results revealed that the amount of dye in a freshly made flap was rarely as much as in normal skin, and skin with less than 20 percent of the dye of control areas usually sloughed, although there were exceptions. In the future the instrument will be improved, and its readings will be compared to those obtained from radioactive microspheres, the present "gold standard" of techniques to measure vascularity. The instrument can be used to estimate the blood supply to any tissue and seems to be as reliable as the dermofluorometers already on the market.     

Fluorescence analysis of cells using a laser light source

A quantitative microfluorometric instrument is described that employs a helium cadmium laser (442 nm) as the illumination source. The instrument consists of a double grating monochromator in front of a gallium arsenide photomultiplier that is interfaced with a desktop computer. The versatility of the instrument in making quantitative nucleic acid measurements on acridine orange and Feulgen-Schiff stained cells is demonstrated. The ploidy levels of several populations are easily determined, and the Feulgen fluorescent emissions are considerably greater than those obtained with a standard mercury lamp.     

Ensouled bodies: the continuity of the theme of 'the body as instrument'.

This paper deals squarely with the concept of instrument, specifically, a music instrument, as a unifying agent. The topic occupied writers from Plato, through Plotinus (3rd century, CE), writers within the period known as the European Latin-based Middle Ages, and, as we will see, beyond. Seen from a historical perspective as it recurs, the topic of "body as instrument" is evidence that mind-body interactive reciprocity is not by any means solely a recent multifaceted biochemical, neurological, psychological, and cognitive, subject of inquiry; but, rather, constituted a carefully-articulated topic of discussion in the past--and, that the results of this encounter of various points of view are indeed useful for us today. Further, that alternative modes of knowledge transmission exist, for example, the allegorical mode.     

数据记忆动物游泳测试仪的研制

目的研制一种用于检测动物负载游泳状况及过程的仪器,用于动物疲劳游泳试验。方法采用不同直径的可调换加载钢球、恒温水池、接近传感器信号转换、51系列单片微机控制和记忆信号。结果研制出一台可同时做六路平行实验的动物游泳测试仪,自动记忆动物在加载的情况下抗疲劳游泳的全过程。结论经36例小鼠实验证明,效果良好,该仪器为动物负载游泳实验提供了一种全新的测试方法。     

生态治理政策工具对农户行为的影响差异研究——以宁夏盐池县为例

政策工具被认为是政府为解决某个公共问题采取的具体手段或措施,一项政策可以视作目标和多种政策工具的组合。在生态治理过程中,不同政策工具对农户行为的刺激程度不同,进而导致不同的政策效果。分离不同政策工具的影响,可为工具选择和政策优化提供科学参考。以盐池县为例,利用基于该县1983-2017年内出台的316份生态政策文本构建的政策工具数据集和VAR模型中的脉冲响应和方差分解方法定量研究了强制型、混合型和自愿型三大类政策工具及十种子工具对农户耕作、放牧、造林3种行为的影响。结果表明：（1）政策工具对农户行为的影响具有时效性,一般在政策出台后2-3年内影响最大,随后逐渐减小并消失,影响持续时间为7-10年。（2）总体来看,政策工具对农户行为的冲击力度较小,冲击范围在0-0.30之间,说明农户行为还受到其他诸多因素的影响。（3）10年累计影响从大到小依次为强制型、混合型、自愿型,其中直接提供和规制两种子工具的影响最大。放牧行为受到政策工具的刺激最大,耕作行为次之,造林行为最小。（4）直接提供工具对耕作行为具有最大正向影响,最大冲击为0.30;规制工具在短期内抑制牲畜数量增长,而直接提供和补贴工具促进牲畜数量增长,且由于冲击曲线存在正负波动,说明政府与农户在牲畜养殖上存在长期博弈;只有规制工具对造林行为具有积极影响,说明造林更多是在政府的主导下进行。建议充分利用政策工具的短期效应,凸显政府角色,及时做好政策效果评估工作,调整工具组合,助力生态目标的实现。     

A simple and biosafe method for isolation of human umbilical vein endothelial cells

Human umbilical vein endothelial cells (HUVEC_S) are used as an irreplaceable tool for the study of vascular diseases. However, the technicians who isolate HUVECs are largely exposed to potential infectious threats. Here we report the development of a specialized instrument to protect researchers from known or unknown infectious agents when they operate on human umbilical cords. This instrument can be assembled by common laboratory supplies and adapted to accommodate umbilical cords of different lengths. When the cord is enclosed within the instrument, the risk of sample contamination and operator infection is greatly reduced. Using our instrument, endothelial cells were successfully isolated from human umbilical veins without contamination. The cells were verified by their cobblestone-like morphology and by immunofluorescence staining (Factor VIII and CD31 positivity and α-SMA negativity). Our instrument simplifies and optimizes the cell extraction process, and most importantly elevates the biosafety to a higher level during the isolation of human umbilical vein endothelial cells.     

High throughput parallel synthesis of oligonucleotides with 1536 channel synthesizer

A 1536 channel oligonucleotide synthesizer, the MultiSyn, was developed with the capability to simultaneously synthesize 1536 oligonucleotides of 20mer length in 10 h. The instrument was designed to synthesize different sequences of various lengths in micro-wells and has synthesized oligonucleotides as long as 119 nt with reasonably good yields using CPG beads of 1000 Å pore size. The instrument consists of four 384 channel synthesis modules. Phosphoramidite chemistry was employed and step yields as high as 99.3% were achieved. The enhancement of oligonucleotide synthesis throughput is accomplished by increasing the spatial density of reaction wells. We have identified several parameters that are critical in achieving a good synthesis yield and negligible failure rate in small reaction wells. The coefficient of variation (CV) of product yields in 1536 reaction wells was 20%. The quality of the product was examined by capillary electrophoresis and mass spectrometry. The instrument has robustly synthesized oligonucleotides of various lengths for use as primers and probes for PCR amplifications, oligonucleotide microarrays and genotyping applications. This high throughput oligonucleotide synthesizer is a useful instrument for genomic applications, which require tens of thousands of probes or primers in a short time.     

Construction of a scale to signal personality disorders in the elderly

Till now, no specific diagnostic instruments to detect personality disorders in the elderly are available. The aim of our study was to contribute to the construction of a reliable en valid instrument for the detection of personality disorders in older adults. Therefore, a draft version of the instrument was constructed both for the patient and the informant. Both the patient and the informant version of the instrument included 52 items with the same content. These items concerned Habitual behaviour (HAB), Biographical information (BIO) and Observation of actual behaviour (OBS). 159 clients of 60 years and older of a Dutch ambulatory mental health care organisation were assessed with the screening instrument. In 96 of the 159 outpatients one or more informants were included. The results indicate that the internal consistency of seven HAB items, nine BIO items and five OBS items was moderate to good with regard to both the patient and informant instrument. Test-retest reliability of the 21 items of the patient instrument was moderate with regard to HAB, excellent with regard to BIO and moderate with regard to OBS. Interrater reliability of OBS was also moderate. The criterion validity (criterion: DSM-IV TR Axis II classification) of HAB, BIO and OBS based on the 21 items of the patient instrument was fair and with regard to the same 21 items of the informant instrument insufficient. In conclusion, sixteen out of 52 potential items of the patient's draft version of the screening instrument can be used to detect a possible personality disorder. These sixteen items from the HAB and BIO scale are named the Gerontological Personality disorder Scale (GPS). Medical doctors, psychologists and nurses working in ambulatory mental health organisation can use the GPS as a resource during the diagnostic process. Whether the GPS can be used beyond mental health organisations, for example by general practitioners is a subject for future studies.     

Flow-system measurement of cell impedance properties.

A flow-system technique has been developed that detects the high-frequency resistance and capacitance changes in a sensing orifice due to the passage of cells through the orifice. The resistance and capacitance changes are related to cell properties such as size, plasma membrane capacitance, and electrical resistivity of the cell interior. The relationship between measured impedances and cellular properties is discussed, and the prototype instrument for making such measurements is described. The instrument can simultaneously detect the dc Coulter volume and two ac parameters related to the complex ac impedance change. Some initial tests of the instrument using plastic microspheres and Chinese hamster ovary cells are described.     

The design of a phonoactograph suitable for study on the influence of pheromones on insect mobility

An instrument for recording changes in insect mobility under the influence of pheromone was described. The instrument was named "phonoactograph" because the intensity of rustle made by insects was utilized as a correlate of their movement. The Colorado beetle males exposed to the action of the female odour increased their mobility significantly.     

An Instrument for Non-Destructive Measurement of the Pressure Potential (Turgor) of Leaf Cells

An instrument is described which permits the non-destructivemeasurement of the mean pressure potential (turgor)of leaf laminacells. Calibration shows that the instrument gives a voltageoutput which is linearly related to mean pressure potentialof living leaf cells as determined with a pressure chamber.Measurements may be made very quickly in the field or controlledenvironment with a resolution of at least 50 k Pa.     

Instrument for Study of Microbial Thermal Inactivation

An instrument was designed for the study of thermal inactivation of microorganisms using heating times of less than 1 sec. The instrument operates on the principle of rapid automatic displacement of the microorganism to and from a saturated steam atmosphere, and the operating temperature range is 50 to 90 C. At a temperature of 70 C, thermometric lag (time required to respond to 63.2% of a step change) of the fluid sample containing microorganisms was 0.12 sec. Heating time required to heat the sample to within 0.1 C of the exposure temperature was less than 1 sec, permitting exposure periods as brief as 1 sec, provided the proper corrections are made for the lethal effect of heating. The instrument is most useful for heat exposure periods of less than 5 min, and, typically, more than 500 samples can be processed for microbial inactivation determinations within an 8-hr period.     

A simple rapid mixing device

An instrument is described for the rapid mixing of solutions. Gas presure, controlled by electronically operated solenoid valves, is used to eject solutions from microsyringes into a stirred solution. It can be used to initiate and quench enzymatic reactions at times down to 0.5 s. Although this time resolution is longer than that of a conventional quenched-flow instrument, it has several advantages. It can be used for volumes of solutions as small as 20 μl. It covers a range of times inaccessible to conventional quenched-flow instruments and manual mixing techniques. Last, the instrument is very simple and can be easily and inexpensively constructed.