Demonstration of a highly-sensitive portable double-flash kinetic spectrophotometer for measurement of electron transfer reactions in intact plants

A highly sensitive, portable spectrophotometer for use in measuring flash-induced absorbance changes in intact leaves is demonstrated. The design of the instrument is modified for whole plant use from that suggested by Joliot and Joliot (Biochim. Biophys. Acta 765, 210–218). The spectrophotometer uses trifurcated light guides to deliver measuring and actinic beams to two comparable areas of the leaf. The measuring beam is provided by a series of short, relatively intense light pulses from a xenon flashlamp in place of the constant weak measuring beam used in conventional machines. The use of a flash measuring beam and differential detection allows for a high signal-to-noise ratio (noise levels of 10^-5A) without significant actinic effects. The time resolution of the instrument is 2 sec and the noise level is independent of the experimental time range. The instrument is battery or mains powered, computer operated, and has a liquid crystal display for computer-user interface and dialogue, and to show the kinetic traces graphically. Wavelength selection is provided by interchangeable interference filters. The instrument can communicate with a laboratory-based computer, receiving programming information and sending experimental data to be processed and plotted. The instrument is demonstrated by following the kinetics of the electrochromic shift, the change in redox states of cytochrome f and the b cytochromes in an intact cucumber leaf, and in the same leaf after infiltration with DCMU.     

Novel linear quadrupole ion trap/FT mass spectrometer: performance characterization and use in the comparative analysis of histone H3 post-translational modifications

We describe the design and performance of a prototype high performance hybrid mass spectrometer. This instrument consists of a linear quadrupole ion trap (QLT) coupled to a Fourier transform ion cyclotron resonance mass analyzer (FTMS). This configuration provides rapid and automated MS and MS/MS analyses, similar to the "data dependent scanning" found on standard 3-D Paul traps, but with substantially improved internal scan dynamic range, mass measurement accuracy, mass resolution, and detection limits. Sequence analysis of peptides at the zeptomole level is described. The recently released, commercial version of this instrument operates in the LC/MS mode (1 s/scan) with a mass resolution of 100 000 and is equipped with automatic gain control to provide mass measurement accuracy of 1-2 ppm without internal standard. Methodology is described that uses this instrument to compare the post-translational modifications present on histone H3 isolated from asynchronously growing cells and cells arrested in mitosis.     

Microsequence analysis of peptides and proteins. V. Design and performance of a novel gas-liquid-solid phase instrument

We describe the construction and performance of a novel, automated, Edman chemistry-based microsequencer. The reagent and solvent delivery system, the reaction cartridge for coupling and cleavage, and the conversion flask are all constructed from chemically inert perfluoroelastomers. The delivery valves are of a new design incorporating the use of electromagnetically actuated solenoids and zero-dead-volume construction, and may be connected in a modular fashion resulting in multiple inputs with a single output line which can be flushed with inert gas. The bottle closures are of a new design based on an all-Teflon compression fitting. The reaction cartridge and conversion flask are thermostated by solid-state heaters in an aluminum block. The overall size of the instrument is 25 X 34 X 14 in. The chemistry utilizes 2% aqueous triethylamine as the coupling base which is delivered to the reaction cartridge via a stream of nitrogen. The "gas-phase" delivery of the coupling base and the cleavage acid (trifluoroacetic acid) is modeled after the method described by R. M. Hewick et al. (J. Biol. Chem. 256, 7990-7997,1981). The instrument has performed well over a period of 3 years in terms of low background peaks, sensitivity in the picomole range, and reliability of operation. The use of economical components, ease of construction and operation, and sensitive analytical capability make this instrument a useful tool for microsequence analysis of peptides and proteins.     

Glucose analysis utilizing immobilized enzymes

The four commercial instruments that measure glucose by incorporation of immobilized reagents are described and compared. The design of the immobilized enzyme or enzymes is shown to be related to the type of instrument. Three of the instruments are of the partitioned enzyme-sensor type requiring an immobilized enzyme capable of rapid, constant flow rate when inserted in a flowing stream. Moderately high enzyme loading is required if the instrument is designed to operate in the equilibrium mode while lower enzyme loading can be tolerated in kinetic mode. Only one instrument is an enzyme electrode in which the immobilized glucose oxidase is in the immediate vicinity of the electrochemical detector. In that case the immobilized enzyme must have very high enzyme activity per unit volume, but need not have high physical durability. The design of the instrument and immobilized enzyme(s) is also affected by whether the instrument is to be used in an industrial or a clinical laboratory.     

多光束中医信息治疗仪的研制

本文介绍了一种应用光子中医学技术防治缺血性疾病的多光束弱激光中医信息治疗仪。该仪器将先进的单片计算机技术,激光技术与光子中医信息疗法融为一体。文章主要介绍了多光束中医信息治疗仪的设计理念及其实现方式。     

嵌入式AFP测试仪的设计

介绍了一个嵌入式AFP测试仪的设计。测试仪以嵌入式微处理器LPC2210为核心,主要包括数据采集、步进电机的驱动及人机交互界面等几部分。测试仪可通过RS232与PC机通讯,进行数据处理及报告分析,具有一定的临床辅助诊断价值。     

生理学实验教学改革实践

介绍了近年来生理学实验课教学改革实践经验:在生理学实验中注重设计性实验与多媒体设备相结合;同时在实验教学中引入记忆法,有利于实验仪器(MS302和MedLeb多媒体教学软件)的规范化操作与管理,也利于学生实验技能素质的提高.     

High sensitivity non‐invasive detection of calcifications deep inside biological tissue using Transmission Raman Spectroscopy

The aim of this research was to develop a novel approach to probe non‐invasively the composition of inorganic chemicals buried deep in large volume biological samples. The method is based on advanced Transmission Raman Spectroscopy (TRS) permitting chemical specific detection within a large sampling volume. The approach could be beneficial to chemical identification of the breast calcifications detected during mammographic X‐ray procedures. The chemical composition of a breast calcification reflects the pathology of the surrounding tissue, malignant or benign and potentially the grade of malignancy. However, this information is not available from mammography, leading to excisional biopsy and histopathological assessment for a definitive diagnosis. Here we present, for the first time, a design of a new high performance deep Raman instrument and demonstrate its capability to detect type II calcifications (calcium hydroxyapatite) at clinically relevant concentrations and depths of around 40 mm in phantom tissue. This is around double the penetration depth achieved with our previous instrument design and around two orders of magnitude higher than that possible when using conventional Raman spectroscopy.

     

A solid-state,portable instrument for measurement of chlorophyll luminescence induction in plants

A newly developed compact instrument is described for the measurement of chlorophyll luminescence induction in plants. The instrument operates with a pulsed light emitting diode (LED) as light source and a photodiode as luminescence detector. A special emitter-detector geometry provides for high irradiance of the sample and efficient collection of luminescence by the detector. With insertion of appropriate filters the same probe is also suited for measuring prompt chlorophyll fluorescence. The instrument shows considerable flexibility with respect to pulse frequency, relative lengths of light/dark intervals and luminescence sampling periods. Due to a selective amplifier system only that part of luminescence is processed which is induced by the individual excitation pulses. By this approach, the problem of slow phase accumulation, encountered with conventional phosphoroscopes, is eliminated. Some examples are given for system operation, demonstrating satisfactory performance in measurements with intact leaves and isolated chloroplasts.     

Design of a multifunctional compliant instrument for minimally invasive surgery

A new multifunctional compliant instrument has been designed for use in minimally invasive surgery. The instrument combines scissors and forceps into a single multifunctional device. The main advantage of using multifunctional instruments for minimally invasive surgery is that instrument exchanges can be reduced, thus reducing procedure time and risk of inadvertent tissue injury during instrument exchanges. In this paper, the length, width, and thickness of the multifunctional compliant mechanism tool tip is optimized to maximize the jaw opening and the grasping force. The optimized design is then modeled to simulate the stresses encountered in the scissors mode. A 5.0 mm diameter stainless steel prototype is fabricated using electro-discharge machining and is shown to grasp and cut successfully.     

An instrument for assessment of videotapes of general practitioners' performance.

OBJECTIVES--To identify those important characteristics of doctors'' and patients'' behaviour that distinguish between "good" and "bad" consultations when viewed on videotape; to use these characteristics to develop a reliable instrument for assessing general practitioners'' performance in their own consultations. DESIGN--Questionnaires completed by patients, general practitioner trainers, and general practitioner trainees. Reliability of draft instrument tested by general practitioner trainers. SETTING--All vocational training schemes for general practice in the Northern region of England. SUBJECTS--First stage: 76 patients in seven groups, 108 general practice trainers in 12 groups, and 122 general practice trainees in 10 groups. Second stage: 85 general practice trainers in 12 groups. MAIN OUTCOME MEASURES--Trainers'' ratings of importance; alpha coefficients of draft instrument by trainee, group, and consultation. RESULTS--6890 characteristics of good and bad consultations were consolidated into a draft assessment instrument consisting of 46 pairs of definitions separated by six point bipolar scales. Nine statement pairs given low importance ratings by trainers were eliminated, reducing the instrument to 37 statement pairs. To test reliability, general practitioner trainers used the instrument to assess three consultations. With the exception of one group of trainers, all alpha coefficients exceeded the acceptable level of 0.80. CONCLUSION--The instrument produced is reliable for assessing general practitioners'' performance in their own consultations.     

Parallel processing and maintaining adequate alignment between instruments and methods

Parallel processing of laboratory tests across more than one instrument platform: permits dealing with increasing workloads; but broadens uncertainty of measurement; minimising measurement uncertainty means keeping assay performances continuously aligned. Important questions are: Why is there the need to demonstrate "acceptable alignment" between methods/instruments? What methods/tools can be used to test method/instrument alignment and how adjustments can be made? What is an "acceptable" alignment? How often should alignments be checked and what is the reasoning for this?     

A laser Doppler scanner for imaging blood flow in skin

This paper describes a novel medical instrument that produces an image of blood flow in the capillaries under the skin surface. A laser beam is used to detect blood cell motion from the Doppler broadening of the laser light scattered from the skin. The image is generated by scanning the laser beam in a raster. The design of a practical clinical instrument is outlined and some preliminary results are presented.     

Cross-cultural adaptation of instruments assessing breastfeeding determinants: a multi-step approach

Background

Cross-cultural adaptation is a necessary process to effectively use existing instruments in other cultural and language settings. The process of cross-culturally adapting, including translation, of existing instruments is considered a critical set to establishing a meaningful instrument for use in another setting. Using a multi-step approach is considered best practice in achieving cultural and semantic equivalence of the adapted version. We aimed to ensure the content validity of our instruments in the cultural context of KwaZulu-Natal, South Africa.

Methods

The Iowa Infant Feeding Attitudes Scale, Breastfeeding Self-Efficacy Scale-Short Form and additional items comprise our consolidated instrument, which was cross-culturally adapted utilizing a multi-step approach during August 2012. Cross-cultural adaptation was achieved through steps to maintain content validity and attain semantic equivalence in the target version. Specifically, Lynn’s recommendation to apply an item-level content validity index score was followed. The revised instrument was translated and back-translated. To ensure semantic equivalence, Brislin’s back-translation approach was utilized followed by the committee review to address any discrepancies that emerged from translation.

Results

Our consolidated instrument was adapted to be culturally relevant and translated to yield more reliable and valid results for use in our larger research study to measure infant feeding determinants effectively in our target cultural context.

Conclusions

Undertaking rigorous steps to effectively ensure cross-cultural adaptation increases our confidence that the conclusions we make based on our self-report instrument(s) will be stronger. In this way, our aim to achieve strong cross-cultural adaptation of our consolidated instruments was achieved while also providing a clear framework for other researchers choosing to utilize existing instruments for work in other cultural, geographic and population settings.

     

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.     

Application of type synthesis theory to the redesign of a complex surgical instrument

Surgical instruments consist of basic mechanical components such as gears, links, pivots, sliders, etc., which are common in mechanical design. This paper describes the application of a method in the analysis and design of complex surgical instruments such as those employed in laparoscopic surgery. This is believed to be the first application of type synthesis theory to a complex medical instrument. Type synthesis is a methodology that can be applied during the conceptual phase of mechanical design. A handle assembly from a patented laparoscopic surgical stapler is used to illustrate the application of the design method developed. Type synthesis is applied on specific subsystems of the mechanism within the handle assembly where alternative design concepts are generated. Chosen concepts are then combined to form a new conceptual design for the handle assembly. The new handle assembly is improved because it has fewer number of parts, is a simpler design and is easier to assemble. Surgical instrument designers may use the methodology presented here to analyze the mechanical subsystems within complex instruments and to create new options that may offer improvements to the original design.     

Perceptual characterization and analysis of aroma mixtures using gas chromatography recomposition-olfactometry

This paper describes the design of a new instrumental technique, Gas Chromatography Recomposition-Olfactometry (GC-R), that adapts the reconstitution technique used in flavor chemistry studies by extracting volatiles from a sample by headspace solid-phase microextraction (SPME), separating the extract on a capillary GC column, and recombining individual compounds selectively as they elute off of the column into a mixture for sensory analysis (Figure 1). Using the chromatogram of a mixture as a map, the GC-R instrument allows the operator to "cut apart" and recombine the components of the mixture at will, selecting compounds, peaks, or sections based on retention time to include or exclude in a reconstitution for sensory analysis. Selective recombination is accomplished with the installation of a Deans Switch directly in-line with the column, which directs compounds either to waste or to a cryotrap at the operator's discretion. This enables the creation of, for example, aroma reconstitutions incorporating all of the volatiles in a sample, including instrumentally undetectable compounds as well those present at concentrations below sensory thresholds, thus correcting for the "reconstitution discrepancy" sometimes noted in flavor chemistry studies. Using only flowering lavender (Lavandula angustifola 'Hidcote Blue') as a source for volatiles, we used the instrument to build mixtures of subsets of lavender volatiles in-instrument and characterized their aroma qualities with a sensory panel. We showed evidence of additive, masking, and synergistic effects in these mixtures and of "lavender' aroma character as an emergent property of specific mixtures. This was accomplished without the need for chemical standards, reductive aroma models, or calculation of Odor Activity Values, and is broadly applicable to any aroma or flavor.     

Developing a theory-based instrument to assess the impact of continuing professional development activities on clinical practice: a study protocol

Background

Continuing professional development (CPD) is one of the principal means by which health professionals (i.e. primary care physicians and specialists) maintain, improve, and broaden the knowledge and skills required for optimal patient care and safety. However, the lack of a widely accepted instrument to assess the impact of CPD activities on clinical practice thwarts researchers' comparisons of the effectiveness of CPD activities. Using an integrated model for the study of healthcare professionals' behaviour, our objective is to develop a theory-based, valid, reliable global instrument to assess the impact of accredited CPD activities on clinical practice.

Methods

Phase 1: We will analyze the instruments identified in a systematic review of factors influencing health professionals' behaviours using criteria that reflect the literature on measurement development and CPD decision makers' priorities. The outcome of this phase will be an inventory of instruments based on social cognitive theories. Phase 2: Working from this inventory, the most relevant instruments and their related items for assessing the concepts listed in the integrated model will be selected. Through an e-Delphi process, we will verify whether these instruments are acceptable, what aspects need revision, and whether important items are missing and should be added. The outcome of this phase will be a new global instrument integrating the most relevant tools to fit our integrated model of healthcare professionals' behaviour. Phase 3: Two data collections are planned: (1) a test-retest of the new instrument, including item analysis, to assess its reliability and (2) a study using the instrument before and after CPD activities with a randomly selected control group to explore the instrument's mere-measurement effect. Phase 4: We will conduct individual interviews and focus groups with key stakeholders to identify anticipated barriers and enablers for implementing the new instrument in CPD practice. Phase 5: Drawing on the results from the previous phases, we will use consensus-building methods to develop with the decision makers a plan to implement the new instrument.

Discussion

This project proposes to give stakeholders a theory-based global instrument to validly and reliably measure the impacts of CPD activities on clinical practice, thus laying the groundwork for more targeted and effective knowledge-translation interventions in the future.

     

An instrument design for non-contact detection of biomolecules and minerals on Mars using fluorescence

We discuss fluorescence as a method to detect polycyclic aromatic hydrocarbons and other organic molecules, as well as minerals on the surface of Mars. We present an instrument design that is adapted from the ChemCam instrument which is currently on the Mars Science Lander Rover Curiosity and thus most of the primary components are currently flight qualified for Mars surface operations, significantly reducing development costs. The major change compared to ChemCam is the frequency multipliers of the 1064 nm laser to wavelengths suitable for fluorescence excitation (266 nm, 355 nm, and 532 nm). We present fluorescence spectrum for a variety of organics and minerals relevant to the surface of Mars. Preliminary results show minerals already known on Mars, such as perchlorate, fluoresce strongest when excited by 355 nm. Also we demonstrate that polycyclic aromatic hydrocarbons, such as those present in Martian meteorites, are highly fluorescent at wavelengths in the ultraviolet (266 nm, 355 nm), but not as much in the visible (532 nm). We conclude that fluorescence can be an important method for Mars applications and standoff detection of organics and minerals. The instrument approach described in this paper builds on existing hardware and offers high scientific return for minimal cost for future missions.     

The rapid electrophoresis of proteins on polyacrylamide gel

A system for express electrophoretic separation of proteins in a thin layer of polyacrylamide gel covalently attached to a glass base has been proposed. A technology of covalent attachment of gel to a glass base has been developed and a small-scale instrument has been constructed which allows to carry out the separation, staining and electrophoregram washing off for 60 min. The quality of the cleaved protein mixtures is not worse than the electrophoregrams obtained using the "Phase System T. M." instrument of "Pharmacia".