scholarly journals Microgel that swims to the beat of light

2021 ◽  
Vol 44 (6) ◽  
Author(s):  
Ahmed Mourran ◽  
Oliver Jung ◽  
Rostislav Vinokur ◽  
Martin Möller
Keyword(s):  
Body Shape ◽  
Cold Water ◽  
Pulse Sequence ◽  
Temperature Cycling ◽  
Infrared Light ◽  
Coupled Modes ◽  
Temperature Changes ◽  
Rectangular Container ◽  
Forward Locomotion ◽  
Dispersed Gold

Abstract Complementary to the quickly advancing understanding of the swimming of microorganisms, we demonstrate rather simple design principles for systems that can mimic swimming by body shape deformation. For this purpose, we developed a microswimmer that could be actuated and controlled by fast temperature changes through pulsed infrared light irradiation. The construction of the microswimmer has the following features: (i) it is a bilayer ribbon with a length of 80 or 120 $$\upmu $$ μ m, consisting of a thermo-responsive hydrogel of poly-N-isopropylamide coated with a 2-nm layer of gold and equipped with homogeneously dispersed gold nanorods; (ii) the width of the ribbon is linearly tapered with a wider end of 5 $$\upmu $$ μ m and a tip of 0.5 $$\upmu $$ μ m; (iii) a thickness of only 1 and 2 $$\upmu $$ μ m that ensures a maximum variation of the cross section of the ribbon along its length from square to rectangular. These wedge-shaped ribbons form conical helices when the hydrogel is swollen in cold water and extend to a filament-like object when the temperature is raised above the volume phase transition of the hydrogel at $$32\,^{\circ } \hbox {C}$$ 32 ∘ C . The two ends of these ribbons undergo different but coupled modes of motion upon fast temperature cycling through plasmonic heating of the gel-objects from inside. Proper choice of the IR-light pulse sequence caused the ribbons to move at a rate of 6 body length/s (500 $$\upmu $$ μ m/s) with the wider end ahead. Within the confinement of rectangular container of 30 $$\upmu $$ μ m height and 300 $$\upmu $$ μ m width, the different modes can be actuated in a way that the movement is directed by the energy input between spinning on the spot and fast forward locomotion. Graphic abstract

scholarly journals Dynamic motion monitoring of a 3.6 km long steel rod in a borehole during cold-water injection with distributed fiber-optic sensing

2021 ◽  
Author(s):  
Martin P. Lipus ◽  
Felix Schölderle ◽  
Thomas Reinsch ◽  
Christopher Wollin ◽  
Charlotte M. Krawczyk ◽  
...  
Keyword(s):  
Thermal Stresses ◽  
Fiber Optic ◽  
Cold Water ◽  
Water Injection ◽  
Strain Sensing ◽  
Distributed Temperature Sensing ◽  
Stick Slip ◽  
Temperature Changes ◽  
Flow Monitoring ◽  
Sucker Rod

Abstract. Fiber-optic distributed acoustic sensing (DAS) data finds many applications in wellbore monitoring such as e.g. flow monitoring, formation evaluation, and well integrity studies. For horizontal or highly deviated wells, wellbore fiber-optic installations can be conducted by mounting the sensing cable to a rigid structure (casing/tubing) which allows for a controlled landing of the cable. We analyze a cold-water injection phase in a geothermal well with a 3.6 km long fiber-optic installation mounted to a ¾” sucker-rod by using both DAS and distributed temperature sensing (DTS) data. During cold-water injection, we observe distinct vibrational events (shock waves) which originate in the reservoir interval and migrate up- and downwards. We use temperature differences from the DTS data to determine the theoretical thermal contraction and integrated DAS data to estimate the actual deformation of the rod construction. The results suggest that the rod experiences thermal stresses along the installation length – partly in the compressional and partly in the extensional regime. We find strong evidence that the observed vibrational events originate from the release of the thermal stresses when the friction of the rod against the borehole wall is overcome. Within this study, we show the influence of temperature changes on the acquisition of distributed acoustic/strain sensing data along a fiber-optic cable suspended along a rigid but freely hanging rod. We show that observed vibrational events do not necessarily originate from induced seismicity in the reservoir, but instead, can originate from stick-slip behavior of the rod construction that holds the measurement equipment.

scholarly journals Testing the Effects of Seacoast Atmosphere on Tantalum Capacitors

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Johanna Virkki ◽  
Pasi Raumonen
Keyword(s):  
High Temperature ◽  
Salt Spray ◽  
Significant Risk ◽  
Temperature Cycling ◽  
High Humidity ◽  
Temperature Changes ◽  
Effects Of Temperature ◽  
Salt Fog ◽  
Very High ◽  
Salt Spray Testing

The goal of this research was to test the effects of seacoast atmosphere on tantalum capacitors. Four tests were chosen for this purpose: the 85/85 test was chosen for testing the effects of the combination of high humidity and high temperature, salt spray testing was done for examining the effects of high humidity and salt, temperature cycling test was applied for testing the effects of temperature changes, and a 100% RH humidity test was developed for examining the effects of very high humidity. The results show that combination of high humidity and high temperature did not possess a significant risk for these capacitors during their normal use. Very high humidity and radical temperature changes both affected the breakdown voltages of tantalum capacitors. Salt fog caused corrosion of these components and had a small effect on breakdown voltage but did not have an effect on capacitance or ESR.

scholarly journals Energetically Defining the Thermal Limits of the Snow Crab

1989 ◽  
Vol 145 (1) ◽  
pp. 371-393 ◽  
Author(s):  
TIMOTHY P. FOYLE ◽  
RONALD K. O'DOR ◽  
ROBERT W. ELNER
Keyword(s):  
Food Consumption ◽  
Cold Water ◽  
Caloric Intake ◽  
Oxygen Demand ◽  
Energy Budgets ◽  
Snow Crab ◽  
Temperature Sensitive ◽  
Growth Equation ◽  
Temperature Changes ◽  
Lactate Levels

The snow crab, Chionoecetes opilio, is a cold-water species found naturally at temperatures below 5°C. Its physiology and energetics were examined to understand the metabolic limitations that restrict the snow crab to these temperatures. The species is not confined to cold water because of a limited respiratory system. Routine oxygen demand can be met even at lethal temperatures of 18°C (56 mg O2kg−1h−1, with a Q10 of 2.2). Blood lactate levels remain below 1.5 mmol l−1 and actually decline slightly with temperature. Energy budgets, which were constructed from an examination of oxygen uptake, activity and food consumption in morphometrically mature male animals between 0 and 18°C, indicate that the snow crab is energetically restricted to cold water. Rising metabolic costs overtake caloric intake around 7°C. This is probably due to digestive metabolism which is temperature-sensitive. Food consumption increases up to 6°C but then falls. Crabs stop feeding above 12°C. Although the growth equation is positive between 1 and 7°C, it becomes slightly negative below 1°C. This observation is unexpected since snow crabs are commonly found between 0 and 1°C. Slight temperature changes in the natural environment may, therefore, regulate growth and reproduction in this species.

Downhole Fluid Analysis During Wellbore Sampling at High Temperatures Using a Pyroelectric Array Spectrometer

2021 ◽  
Vol 73 (05) ◽  
pp. 41-43
Author(s):  
Emeakpo Ojonah
Keyword(s):  
High Temperature ◽  
Incident Radiation ◽  
Ferroelectric Materials ◽  
Infrared Light ◽  
Pyroelectric Detector ◽  
Temperature Changes ◽  
Fluid Identification ◽  
Fluid Analysis ◽  
Pyroelectric Detectors ◽  
Contamination Levels

While the world is transitioning into a greener and less-carbon-rich energy source, the fact remains that there is a growing need for exploration and production of hydrocarbons in previously untapped resources. These frontier reservoirs, while extremely hot, are prolific and make the footprint of the exploration activity much smaller than shallower drilling, which would require many more wells to deliver the same amount of hydrocarbon. These frontier wells, classified as high-pressure/high-temperature (HP/HT) wells, are defined as wells with reservoir or bottomhole temperatures higher than 300°F and which require pressure-control equipment with a rating above 10,000 psi. HP/HT wells can be found offshore in the North Sea and Gulf of Mexico, or on land—as seen recently in the Gongola Basin. Fluid identification, which is a critical process in fluid sampling, continues to be a challenge in temperatures above 350°F. At temperatures up to 450°F, fluid identification is currently achieved by bubblepoint and compressibility measurements, which cannot quantitatively measure contamination levels of the subject sample fluid. A possible solution to this problem would involve using pyroelectric detectors in the process of estimating a property of a downhole fluid. The method and apparatus in this approach involves exposing a fluid to modulated light downhole and sensing changes in the intensity of infrared radiation from the downhole fluid, to estimate the level of filtrate contamination and other properties. The pyroelectric detector senses changes in the intensity of light by con-verting the transient changes in temperature of its detector and performs the spectroscopic fluid analysis by optically filtering the light allowed to impinge on it, converting the changes in temperature of the pyroelectric detector to a signal which can then be used to estimate the property of the downhole fluid. If successfully implemented, this would enable the wireline-logging industry to develop an optical fluid analyser capable of quantitatively measuring fluid contamination levels in high-temperature (greater than 300°F) environments. Theory Pyroelectric infrared detectors (PIR) convert the changes in incoming infrared light to electric signals. Pyroelectric materials are characterized by having spontaneous electric polarization, which is altered by temperature changes as infrared light illuminates the elements. Pyroelectric detectors (Fig. 1) are thermal detectors, meaning they produce a signal in response to a change in their temperature. Below a case temperature (Tc) known as the Curie point, ferroelectric materials such as lithium tantalate exhibit a large spontaneous electrical polarization. If the temperature of such a material is altered, for example by incident radiation, the polarization changes. This change in polarization may be observed as an electrical signal when electrodes are placed on opposite faces of a thin slice of the material to form a capacitor. When the polarization changes, if the external impedance is comparatively high, the charges induced in the electrodes can be made to produce a voltage across the slice. The sensor will only produce an electrical output signal when the temperature changes; that is, when the level of incident-radiation changes.

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