Crocodile Clips Research Articles

Graphite-paper circuit elements: Resistor, capacitor, and π value estimation

Graphite, an allotrope of carbon, is also a moderately good conductor of electricity. The shading pencil lead consists of graphite mixed with clay and, therefore, can conduct electricity, allowing one to construct and demonstrate different properties and the underlying concepts of circuit elements. The grade displayed on the pencil relates to the graphite-to-clay ratio, with higher B grades indicating a higher graphite-to-clay ratio. In this paper, the main objective is to show the dependence of resistance and capacitors on different physical parameters and to calculate the value of π electrically. The materials used in this activity are readily available, affordable, and suitable for demonstration purposes. The materials used to perform these activities are shading pencils of different grades, A-4 size papers, crocodile clips, and an LCR meter.

Comparative electrocardiographic study of the Asian freshwater box turtle Cuora flavomarginata and the Asian yellow pond turtle Mauremys mutica using non-invasive methods.

Evaluation of cardiac function is an integral part of clinical examination of chelonians. However, information about electrocardiography (ECG) in turtles and tortoises is limited and fragmentary. Its application is limited due to the lack of ECG reference values. This study aimed to compare specific ECG parameters using non-invasive methods in the Asian box turtle Cuora flavomarginata (CF) and the Asian yellow pond turtle Mauremys mutica (MM). We included 116 clinically healthy and conscious turtles. Two non-invasive methods, using adhesive patches or crocodile clips, for ECG were applied where possible. The ambient temperature was within the preferred optimum temperature zone of both species. We used specific digital ECG monitoring equipment to record the ECG data and analysed the data using specific software. The MM group showed better ECG quality and lower heart rate than the CF group. Comparing both methods, the adhesive patches method yielded higher ECG quality in the CF group, while the crocodile clips method yielded higher ECG quality in the MM group. The study population was selected as presumed healthy turtles; the presence of systemic or cardiac disease could not be excluded completely due to limited investigation. Both ECG methods were clinically potentially useful for obtaining ECG parameters; the ECG quality was influenced by the method used.

A Review on Electro acupuncture

Acupuncture is a traditional Chinese treatment for pain. Acupuncture is a 3000-year-oldtraditional therapy from China. Electroacupuncture is similar to traditional acupuncture in that it uses electrical stimulation. It works similarly to orthodox acupuncture in that it excites the same regions. As with conventional acupuncture, needles are inserted at designated points on the body. The needles are then coupled to a gadget that leverages tiny clips to establish a consistent electric pulse. These devices alter the frequency and strength of the impulses based on the condition being treated. Electroacupuncture uses two or more needles at the same time to allow impulses to pass from one needle to the next. This can be performed by using a standard TENS machine attached to the needles via cables and crocodile clips by using commercially available electroacupuncture machines.

Coil Selection, Handling and Troubleshooting in Detachment Failure

The first coil should be as thick, long, and large as possible. A retrospective study at the Toranomon Hospital revealed that if the volume of the first coil is 1/3rd or more of the total coil volume, there are less chances of retreatment. Thus, a thick and long first coil contributes to stable long-term anatomical results. The length of the first coil should be approximately 8% of the volume of the aneurysm. After the placement of the first coil, a smaller and shorter coil should be placed sufficiently close to it to complete the procedure. The goal is to achieve prevention of acute re-rupture in ruptured acute aneurysms and life-long prevention of rupture in unruptured asymptomatic aneurysms. If the coil does not detach, check the position of the detachment point, and replace the power supply. In addition, refer to the direction for use of the device for prevention of coil disconnection failure and countermeasures. Although it is not a recommended method, a method of rotating the delivery wire at the detached position to thread the coil and a method of reconstructing the electric circuit with a crocodile clip has been reported.

Design and application of a new magnetic joint for electroacupuncture instrument

Combined with the material characteristics of acupuncture needle, new connection technology and injection moulding technology, and through mechanical test, a new type of magnetic joint for electroacupuncture instrument, with regular appearance and simple manufacturing process, is developed, which can be connected with acupuncture needle in close range. This joint is composed of the inner magnet joint and the outer joint protective sleeve. The new conductive adhesive is used to simplify the manufacturing process. Its advantages include connection with acupuncture needle by magnetic force, being convenient to store when idle and easy to switch to the working state, and quick disconnection in case of emergency. This joint is connected safely and firmly with acupuncture needle by magnetic force, which shortens the operation time, improves the working efficiency, and effectively solves the problems existing in the crocodile clip connector.

Difference in the Amount of Voltage between Solid and Liquid Form of Bilimbi Fruit as an Alternative Energy Source

The present study aimed to discover whether there was a difference in the amount of voltage between liquid bilimbi and fresh bilimbi fruit as an alternative energy source. The research samples were 100 grams of fresh bilimbi and 100 grams of liquid bilimbi. The samples were connected to a multimeter through zinc plate and copper plate using a crocodile clip cable. After connected, the voltage measurement of the bilimbi was carried out five times in order to obtain accurate data. The collected data were averaged, and the difference between the two samples was calculated. The results showed that the average amount of voltage from liquid bilimbi was 0.72 V while the average amount of voltage from fresh bilimbi was 1.42 V. Thus, the difference between the two forms of bilimbi was 0.7 V. In conclusion, there was a difference in the amount of voltage produced by liquid bilimbi and fresh bilimbi fruit as an alternative energy source in which fresh bilimbi fruit had a higher amount of voltage than the liquid bilimbi.

Application of electrokinetic in controlling heavy metals migration in sand: A feasibility study

Uncontrolled migration of heavy metals from human activities in the subsurface can lead to the degradation of environmental quality and potential use of soil and groundwater. This paper studies the feasibility of using electrokinetics in controlling the migration of heavy metals in sand. Copper and iron (initial concentration of 100 mgL-1) are the target heavy metals in this study as they are the most commonly found heavy metals from human activities such as mining and land filling. The performance of electrokinetic in controlling the migration of these heavy metals is tested in a sand tank at combination of water velocity and electrical gradient of 1.3 cm h-1, 0.5 V cm-1 and 0.88 cm h-1, 1 V cm-1, respectively. The formation of gas at electrodes, scouring on carbon anode and corrosion of crocodile clips during experiment (0.88 cm h-1, 1 V cm-1) showed the occurrence of electrokinetics. Further studies need to be conducted to optimize the operating conditions for effective application of electrokinetic in controlling heavy metals migration in sand.

075 CROCODILE CLIPS: A NEW TECHNIQUE TO DELIVER RADIOFREQUENCY ENERGY THROUGH A BROCKENBROUGH NEEDLE TO FACILITATE DIFFICULT TRANSSEPTAL PUNCTURE. A SINGLE CENTRE EXPERIENCE

Introduction Transseptal puncture (TSP) using a Brockenbrough needle (BN) may be unsuccessful due to a thickened or fibrosed intra-atrial septum. This is especially true of redo procedures which are increasingly encountered. We describe our novel crocodile clip method and experience of using radio-frequency (RF) energy delivered via a standard BN to facilitate difficult TSP. Method and results Our transseptal puncture technique uses an SL1 sheath and BN. The BN is passed up the sheath several times and the sheath is flushed outside the body to protect against shards. The BN is then placed at the fossa ovalis (FO) and position is confirmed via fluoroscopy in standard orthogonal LAO and RAO views. Contrast is injected to visualise tenting, but not staining, of the FO. Puncture is attempted but if unsuccessful with our usual pressure RF energy is used via our crocodile clip technique. A non-sterile ablation catheter is attached to the proximal end of the BN using sterile crocodile clips and using a standard generator in unipolar mode we deliver RF energy of 20 W for up to 10 s at a time. Care must be taken so that the BN and crocodile clips do not touch the skin. Puncture is confirmed by operator feel, fluoroscopy and pressure monitoring. Our Initial cases were trans-oesophageal echocardiography (TOE) guided but later procedures used fluroscopy alone. Our experience of this technique was reviewed using procedural notes and medical records. Over 36 months, 244 left atrial procedures were performed by two operators at our tertiary centre. 49 cases were redo procedures. RF assisted TSP was used in 23 procedures (17 males, 6 females, Mean age 63±10). In total 13/195 (6.66%) of first time procedures had resistant atrial septa compared to 10/49 (20.4%) of ablation procedures requiring redo TSP. TOE was used in 8 cases, 15 were performed with fluoroscopy only. RF was successful after a median 2 bursts (max 4). There were no complications acutely or at follow-up (mean 10.4 months) Conclusions RF is an effective tool to use in challenging TSP and is easily incorporated into normal practice with a variety of AF ablation techniques. Previous case series have described TSP with direct contact between the BN an ablation catheter or a diathermy needle without complication. Our technique only requires a non-sterile reusable catheter and the additional cost is negligible; being only the one-off cost of crocodile clips and their sterilisation between cases.

Electrode-Skin contact impedance: In vivo measurements on an ovine model

The problem of electrical impedance between the skin and the electrode is an on-going challenge in bio-electronics. This is particularly true in the case of Electrical Impedance Tomography (EIT), which uses a large number of skin-contact electrodes and is very sensitive to noise. In the present article, contact impedance is measured and compared for a range of electrodes placed on the thorax of an ovine model. The study has been approved by the Westmead Hospital Animal Ethics Committee. The electrode models that were employed in the research are Ag/AgCl electrodes (E1), commonly used for ECG and EIT measurements in both humans and animal models, stainless steel crocodile clips (E2), typically used on animal models, and novel multi-point dry electrodes in two modifications: bronze plated (E3) and nickel plated (E4). Further, since the contact impedance is mostly attributed to the acellular outer layer of the skin, in our experiment, we attempted to study the effect of this layer by comparing the results when the skin is intact and when electrodes are introduced underneath the skin through small cuts. This boundary effect was assessed by comparison of measurements obtained during E2 skin surface contact, and sub-cutaneous contact (E5). Twelve gauge intradermal needles were also tested as an electrode (E6). The full impedance spectrum, from 500 Hz to 300 kHz, was recorded, analysed and compared. As expected, the contact impedance in the more invasive cases, i.e the electrodes under the skin, is significantly lower than in the non-invasive cases. At the frequency of 50 kHz which is commonly used in lung EIT acquisition, electrodes E3, E4 and E6 demonstrated contact impedance of less than 200 Ω, compared to more than 400 Ω measured for electrodes E1, E2 and E5. In conclusion, the novel multipoint electrodes proved to be best suited for EIT purposes, because they are non-invasive and have lower contact impedance than Ag/AgCl and crocodile clips, in both invasive and non-invasive cases. This further prompted us to design a flexible electrode belt using the novel multi-point electrodes for lung EIT on animal models.

Electrical resistance measurement methods and electrical characterization of poly(3,4‐ethylenedioxythiophene)‐coated conductive fibers

AbstractTextile fibers and yarns of high conductivity, and their integration into wearable textiles for different electronic applications, have become an important research field for many research groups throughout the world. We have produced novel electrically conductive textile yarns by vapor‐phase polymerization (VPP) of a conjugated polymer, poly(3,4‐ethylenedioxythiophene) (PEDOT), on the surface of commercially available textile yarns (viscose). In this article, we have presented a novel setup for electrical resistance measurements, which can be used not only for fibrous structures but also for woven structures of specific dimensions. We have reported a two‐point resistance‐measuring method using an already manufactured setup and also a comparison with the conventionally used method (so‐called crocodile clip method). We found that the electrical properties of PEDOT‐coated viscose fibers strongly depend on the concentration of oxidant (FeCl3) and the doping (oxidation) process of PEDOT. To evaluate the results, we used mass specific resistance values of PEDOT‐coated viscose yarns instead of normal surface resistance values. The voltage–current (V–I) characteristics support the ohmic behavior of coated fibers to some extent. Monitoring of the charging effect of the flow of current through conductive fibers for prolonged periods of time showed that conductivity remains constant. The change in electrical resistance values with increase in the length of coated fibers was also reported. The resistance‐measuring setup employed could also be used for continuous measurement of resistance in the production of conductive fibers, as well as for four‐point resistance measurement. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Force-controlled lifting of molecular wires

Lifting a single molecular wire off the surface with a combined frequency-modulated atomic force and tunneling microscope it is possible to monitor the evolution of both the wire configuration and the contacts simultaneously with the transport conductance experiment. In particular, critical points where individual bonds to the surface are broken and instabilities where the wire is prone to change its contact configuration can be identified in the force gradient and dissipation responses of the junction. This additional mechanical information can be used to unambiguously determine the conductance of a true molecular wire, that is, of a molecule that is contacted via a pointlike ``crocodile clip'' to each of the electrodes but is otherwise free.

A New Cheap and Efficient Single‐Grain Shatter Tester for Use in Rice Breeding

ABSTRACTGrain shattering, also called grain shedding, is the relative ease with which rice (Oryza sativa L.) seed is dislodged from the pedicel at maturity. Several qualitative methods have been used to assess grain shattering and they tend to underestimate yield loss. Equipments available for quantitative assessment of grain shattering are mostly laboratory based. However, a recently developed prototype in Japan for fieldwork can be used, but the cost is prohibitive. An improved grain‐shattering tester that uses a hand‐held device has been developed and reported here. It is an improvement over the stationary laboratory device. It has the following modifications: a crocodile clip instead of a bench clamp and a helical spring for testing tensile material instead of tension gauge. The new device is affordable, handy for fieldwork, and effective for large experimental trials. This equipment was designed and developed at the University of KwaZulu‐Natal (UKZN) mechanical workshop (Pietmeritzburg, South Africa). Its efficiency was tested at the National Crops Resources Research Institute (NaCRRI) at Namulonge, Uganda. The efficiency was tested by first estimating yield loss in selected test plants using a method that involves shaking panicles. This finding was compared with the minimum force required to dislodge the grains using this new device and a high correspondence of R2 = 99.9% was found. This new equipment has therefore been recommended for field assessment of grain shattering.

THE VALUES OF SOME ECG COMPONENTS IN DAIRY COWS, USING DUBOIS LEADS

Our purpose in this study was to obtain data regarding the values of some electrocardiographic components in 46 healthy dairy caws in different phase of lactation, aged between 4 and 9 years old. We recorded ECG in cattle using lead II of Dubois leads, because the recording is easy to „read” (the electrocardiographic waves have a high amplitude and they are easy to observe). Materials used for recording ECG in caws are represented by the following: the ECG machine, the electrodes that transmit the electric heart field to the heart to ECG machine and the conduction substance which makes the contact between electrodes and animal’s skin. For recording ECG in caws we used crocodile clips (because they are better than other captators: metal slates or cups). We also, used alchool or ECG special gel, as contact solution between electrodes and animal’s skin. The ECG parameters used for recording ECG in dairy cattle were 10 milimeters for the amplitude of 1 milivolt and paper speed 25 mm/sec (because dairy cattle have a low heart rate). We obtained the following results: length of P wave was 0.087 ± 0.002 seconds (average and the average standard error); duration of ventricular complex was 0.075 ± 0.002 seconds, length of T wave was 0.085 ± 0.002 seconds. Regarding the duration of some segments and intervals, we obtained the following values: length of PR segment was 0.127 ± 0.003 seconds, PR interval duration was 0.215 ± 0.004 seconds, QT interval was 0.371 ± 0.008 seconds, PT interval duration was 0.588 ± 0.008 seconds, duration of TP segment was 0.167 ± 0.009 seconds; length of ST segment was 0.207 ± 0.006 seconds, duration of RR interval was 0.760 ± 0.017 seconds. The heart rate was 80.18 ± 1.796. Comparing our results to the other found in the literature in the field, we observe that our dates are alike, regarding the value of electrocardiographic components. We consider that the recording and interpretation ECG in cattle is useful in many medical-veterinarian decisions, because they permit to observe many heart diseases in cattle (miocardic dystrophy, atrial and ventricular enlargements, pericardium effusion, etc).

Reviews: Real-PCB

Real-PCB is a schools level PCB layout software, from the makers of Easy-PC and distributed by Crocodile Clips. It is generally very user-friendly and good value for money. It works well, is reasonably easy to navigate and largely does what it says on the tin.

TEACHING NOTES

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REVIEWS

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TEACHING NOTES

TEACHING NOTES

Electrical stimulation of rats: Part 2—The effect of electrical parameters on muscle tension and post-Mortem glycolysis

Anaesthetized rats were used as a model to determine the effect of changes in electrical stimulation parameters on the pH fall of the M. longissimus dorsi and M. triceps surae and tension development by the M. triceps surae. Stimulation 5 min before decapitation resulted in a reduced post-stimulation fall in pH. Tension development resulting from stimulation of the sciatic nerve decreased rapidly 5 min after decapitation and ceased 30 min after decapitation, whereas a current pathway through the muscle was still effective. Post-stimulation pH fall was less in the leg not in the stimulation pathway, indicating a lack of crossover effect from one leg to the other; but the difference diminished as stimulation voltage increased. For direct stimulation, 20 V produced a maximal response in the stimulated leg; at least twice that voltage was required for a maximal pH fall in the leg not in the stimulation pathway. The total resistance of the rat with a needle electrode at the nape of the neck and crocodile clips attached to the unskinned legs was 3400 ω, whereas with skinned hindlegs the resistance was 860ω. With this high skin resistance at least 40 V was needed for effective stimulation whereas, for low voltage stimulation of much larger animals, only twice this voltage is used. High contact resistance and unknown current density factors make simple correlations of animal size and voltage effects impossible. The optimal stimulation frequency for rats was 20–30 pulses a second. If the cranial electrode was positive, about 15% more tension was developed than when the cranial electrode was negative. With alternating-polarity pulses, there was a high-low tension response, which was more pronounced at low voltages but evened out as the muscles became exhausted. Alternating and cranial-positive pulses produced similar pH falls but cranial-negative pulses were inferior.

Electrical connections-saving space and cost

The 4 mm insulated terminal which can be used with bare wire connections as well as 4 mm plugs is expensive (15p) and rather bulky. For certain uses two alternatives are worth considering: miniature crocodile clips (3.3p) and single sockets (1.6p) cut from a socket strip intended for use with integrated circuits (ICs).

A compact tank for processing medium quantities of personnel monitoring films.

Many small hospital physics departments provide a radiation film badge monitoring service on a scale which, while not large enough to warrant the purchase of an expensive processing unit, requires something more than a simple development technique. Our department is now required to expand the existing service to a maximum estimated capacity of 200 film badges per fortnight. The processing tank described was designed to deal with a service of this size. It is usually necessary, when developing monitoring or dental films, to ensure that the method of holding the film leaves a minimum mark on the film. The two normal methods of holding the film are (a) by spring or crocodile clip, or (b) in a rectangular frame, the films being placed end-on across each diagonal alternately. The first of these methods marks the film and although holding the film safely, allows considerable movement of the film relative to the holder. Such movement increases the clearance that is necessary between films when in the developer.