Differences in the quality of the photoplethysmograph signal in subjects with and without nail polish

Qualitative indicators are an important element in establishing truth in polygraph examinations. Considering this, a study of the change in the quality of the signal from the photoplethysmograph in subjects who have used nail polish is extremely relevant and requires a comprehensive qualitative study. Th e paper uses general scientifi c and empirical methods of observation and experimentation, and is a comprehensive study of the eff ects of nail polish on the quality of the photoplethysmograph signal. It is the fi rst time that this type of research has been conducted using a comparative analysis of subjects who did and did not use nail polish

Miniature, all-solid-state ion-selective sensor as a detector in autonomous, deployable sensing device

Lowering of the detection limit of ion-selective electrodes (ISEs) as well as their simple construction, low production cost and low power requirements make ISEs an ideal candidate for detector systems that can be integrated into autonomous, deployable sensing devices. Routine analysis and early warning systems are applications that first spring to mind, however great added value can be obtained by integration of many such devices into a wireless sensing network. In this work we describe our work towards the miniaturization of ISEs and their integration of with all-solid-state reference electrode into an all-solid-state sensor with a view of integration in autonomous, deployable sensing device. This work has two avenues: 1) development of a platform that can house all-solid-state ISEs and reference electrodes and 2) development of electronic circuitry for data acquisition and wireless transmission of the data. The latter utilizes novel, in-house made motes (a node in a wireless sensor network that is capable of performing some processing, gathering sensory information and communicating with other connected nodes in the network) that operate at lower frequency and therefore consume lower power then other, commercially available ones. In addition, they are easier to program which bridges the gap of communication between chemists and computer scientists. Intensification of the work in producing all-solid-state reference electrodes has enabled us to work on development of a platform that houses all-solid-state ISEs and reference electrode. We will here describe our progress in this avenue of our research

Integration of miniature, ultrasensitive chemical sensors in microfluidic devices

Simple construction, good detection limit1, very low power demand, and simple experimental setup coupled with miniaturization opportunities arising from solid-state format makes ISEs an excellent prospect for integration in autonomous sensing devices and ultimately their integration in large wireless chemo-sensing networks.2,3 Microfluidics, also known as “lab-on-a-chip” is an emerging technology that is changing the future of instrument design. Microfluidics enables small scale fluid control and analysis, allowing developing smaller, more cost-effective, and more powerful systems.4,5,6 We are working on development of miniature devices featuring sensitive yet simple sensors that could enable rapid access to important environmental information from in-situ deployed sensors, and thereby facilitate timely action to minimize the adverse impact of emerging incidents. Our work involves integration of ultra-sensitive yet simple chemical sensors into a microfluidic device that has integrated wireless communications capabilities. Our ultimate objective is to develop a microfluidic chip that will incorporate polymer-based lead-selective solid-state electrodes. We will test the series of developed chips for the best design to accommodate these sensors. Initially, we are targeting lead-selective sensors and their application to the monitoring of drinking and natural water quality. Our ultimate vision is the development of a microfluidic-based platform with fully integrated screen-printed solid-state ISEs, and the associated reference electrode, which will be suitable for use as a chemo-sensing component in a widely distributed wireless sensor network (WSN) for monitoring the quality of a fresh water system. A key challenge in the realization of this vision is to build in advanced system diagnostics, and particular, sensor status tests using simple electronic signals, in a manner similar to those used in physical transducers.7 In this way, it may be possible to assist in distinguishing sensor malfunction or signal artifacts from real events, even in relatively simple, low cost platforms

A Review of Multidimensional Scaling (MDS) and its Utility in Various Psychological Domains

This paper aims to provide a non-technical overview of multidimensional scaling (MDS) so that a broader population of psychologists, in particular, will consider using this statistical procedure. A brief description regarding the type of data used in MDS, its acquisition and analyses via MDS is provided. Also included is a commentary on the unique challenges associated with assessing the output of MDS. Our second aim, by way of discussing representative studies, is to highlight and evaluate the utility of this method in various domains in psychology

Electrochemical impedance spectroscopy as a tool for probing the functionality of ion-selective membranes

Recent success in lowering of the detection limit of ion-selective electrodes (ISEs) to part-perbillion levels have opened up the possibility for their application in environmental analysis. Its simplicity, low cost, and low power requirement coupled with excellent selectivity and sensitivity make ISEs excellent detecting system in autonomous and deployable sensing devices for routine analysis and as early warning systems. However, the necessity for calibration of detecting systems implies the use of sometimes complicated and costly systems for calibration solution and waste handling, pumps and data acquisition including the labour for system maintenance. Reducing the need for sensor calibration (or its complete elimination) would not only simplify sensing devices and reduce their costs but would allow integration of chemical sensors into the emerging area of wireless sensing networks (WSNs). It is envisioned that this integration will bring new dimensions into chemical sensing and bring benefits in many aspects of human lives. Here, we describe our attempts to address the issue of reducing the need for sensor calibration. The functionality of a typical physical transducer is probed using electrical signals testing its resistance, impedance, conductance etc. We employ a similar strategy and apply relatively simple AC signals to an ion-selective membrane in order to probe its functionality after it has been subjected to conditions that simulate in-situ long-term deployments. For example, we observe the impedance spectra of membranes that have been physically damaged, biofouled and/or have components leached out. Comparing this information with the sensor's potentiometric behaviour, we can draw conclusions regarding the functionality of the devices and their suitability to continue serving as a reliable detectors, for example, in remote locations

Integration of a sensor system into microfluidic chips

There have been considerable developments in the field of potentiometric sensors in recent years mainly with respect to lowering detection limits and making sensors smaller, solid-state, robust and less expensive.[1, 2] In potentiometric measurements two electrodes are needed, an indicator or ion-selective electrode (ISE) and a reference electrode. However, recent progress in the design and characteristics of the indicator electrodes cannot be exploited without similar progress in the design of the reference electrodes. In this paper we present development of chips with fully integrated solid-contact reference (SC-RE) and ion-selective (SC-ISEs) electrodes. In these electrodes, a conducting polymer (CP) (poly(3,4-ethylenedioxythiophene)) is used as the solid contact ion-to-electron transducer[3]. The conducting polymer is deposited using galvanostatic electropolymerization.[4, 5] The ability to produce reliable miniaturized reference electrodes, has given us the opportunity to develop several prototype versions of miniature, solid-contact sensor systems (i.e. with fully integrated ion-selective and reference electrodes) that can be further integrated into microfluidic platforms. We have prepared microchips using different designs to test for the best accommodation of the sensors and to optimise the sensor-chip platform characteristics. Our initial goal is to prepare Pb-ISEs suitable for use as a chemo-sensing component in a widely distributed wireless sensor network (WSN) for monitoring the quality of a fresh water system, together with advanced diagnostics to evaluate the on-going functionality of the sensors using simple electronic signals.[5, 6

Stem formation at alfalfa varieties and correlative dependences with some main parameters

During the period 2006-2009 in IFC-Pleven were studied 9 alfalfa varieties: Europe, Prista 2, Prista 3, Prista 4, Obnova 10, Pleven 6, Dara, Multifoliate and Dama. In the first year of its development alfalfa formed on average 1.42 number of stems per plant. During second and third year their quantity increased to 2.14 and 3.83 number whereafter during fourth year they decreased to 3.28. In all years (except the first year) was found a trend of increase in stem number from spring to autumn regrowth with average values 2.11, 2.85 and 3.05 respectively. Average for the four-year period the greatest number of stems (over the average for the nine studied varieties – 2.67) formed the Multifoliate variety followed by Europe, Prista 4, Obnova 10 and Dama. The varieties which are characterized by less density of stand (number of plants per unit area) had a greater number of stems per plant (r = -0.530). Correlations with mean and high positive value were found between stem formation and amount and distributions of rainfall during vegetation period (r = 0.989), year of alfalfa development (r = 0.861), nodulation (r = 0.763), weight of root mass (r = 0.411) as well as correlations with mean negative value between number of stems and percentage of damaged stems by Apion seniculus (r = -0.456)

CHANGES IN VALUES MEASURED WITH A LASER FLUORESCENCE SYSTEM FOR ENAMEL AND DENTIN ETHCED FOR DIFFERNT TIME INTERVALS - pilot study.

Purpose: The aim of the presented in vitro study was to evaluate the effectiveness of the laser fluorescent device DIAGNOdent in measuring changes in the level of mineralization of intact enamel surfaces etched for different time intervals and intact dentin etched for 30 sec. Material and methods: The study was performed on extracted human teeth. DIAGNOcam was used to measure the values of laser fluorescence of intact enamel and dentinal surfaces. Then the samples were treated with 37% H2PO3 etchant for 5, 30 and 60 sec for enamel surfaces and 30 sec for dentinal. Teeth were rinsed, dried and measured again with DIAGNOdent. Statistical analysis was done using statistical software SPSS 16.0 (SPSS Inc.). Results: After etching the enamel surfaces for 5, 30 and 60 seconds an average increase of 0,5 (0.62-1.1) was detected. The detected average values of increase of laser fluorescence for the enamel were 0.5 for 5 sec. ethching, 0.62 for 30 sec and 1.1 for 60 sec. The average increase for dentine was 0.26. Conclusions: Based on the limitations of the conducted study it may be concluded that changes in the degree of mineralization of tooth structures can be detected by using DIAGNOdent. Enamel etching for 5 sec and 30 sec lead to a comparative degree of change in the laser fluorescence. The obtained values after 60 sec. of etching revealed an almost double increase. The measured changes in enamel after etching are better pronounced than that in dentin

Multi-Parametric Rigid and Flexible, Low-Cost, Disposable Sensing Platforms for Biomedical Applications

The measurement of Na+, K+ and H+ is essential in medicine and plays an important role in the assessment of tissue ischemia. Microfabrication, inkjet- and screen-printing can be used for solid contact ion selective electrodes (ISE) realization; these, however, can be non-standardized, costly and time consuming processes. We present the realization of ISEs on post-processed electrodes fabricated via standardized printed circuit board (PCB) manufacturing techniques. In vitro results are presented from two rigid platforms (32 ISEs) for liquid sample dip-stick measurements and two flexible platforms (6 and 32 ISEs) for post-surgical intestinal tissue monitoring, each with a common reference electrode (RE). These are combined with optimized tetrapolar bioimpedance sensors for tissue ischemia detection. Both electroless and hard gold PCB finishes are examined. Apart from the electroless rigid platform, the rest demonstrated comparable and superior performance, with the pH sensors demonstrating the greatest deviation; the flexible hard gold platform achieved a sensitivity 4.6 mV/pH and 49.2 mV/pH greater than the electroless flexible and rigid platforms, respectively. The best overall performance was achieved with the hard gold flexible platform with sensitivities as large as 73.4 mV/pH, 56.3 mV/log [Na+], and 57.4 mV/log [K+] vs. custom REs on the same substrate. Simultaneous measurements of target analytes is demonstrated with test solutions and saliva samples. The results exhibit superior performance to other PCB-based pH sensors, demonstration of Na+ and K+ PCB-based sensors with comparable performance to potentiometric sensors fabricated with other techniques, paving the way towards mass-produced, low-cost, disposable, multi-parametric chemical sensing diagnostic platforms