scholarly journals Thermocapillary Multidewetting of Thin Films

MRS Advances ◽  
2018 ◽  
Vol 3 (18) ◽  
pp. 977-982 ◽  
Author(s):  
Arielle R. Gamboa ◽  
Michael P. Nitzsche ◽  
Valeria Saro-Cortes ◽  
Tianxing Ma ◽  
Lin Lei ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Thermal Gradient ◽  
Laser Power ◽  
Beam Size ◽  
Melting Points ◽  
Electrospray Deposition ◽  
Several Variables ◽  
Complex Architectures ◽  
Concentric Circles ◽  
Photothermal Methods

ABSTRACTThermocapillary dewetting of liquids and molten films has recently emerged as a viable alternative to conventional microprocessing methods. As this thermal gradient-induced mechanism is universal, it can be applied to any material. This work explores the sequential dewetting of materials with varying melting points, including polymers and metals, to create aligned morphologies. The variation in melting point allows for the dewetting of single layers at a time or mobility-limited simultaneous dewetting. As a result, a variety of multimaterial structures can be produced with built-in alignment, such as arrays of concentric circles, lines with periodic segmentation, or islands on holes. This approach employs photothermal methods to induce the necessary thermal gradient, manipulating several variables in order to influence the consequent structures. Adjusting laser power and light intensity allows for the control of temperature for selective dewetting of films; altering beam size and exposure time affects the extent of dewetting in terms of diameter size; overlap effects and simultaneous dewetting can result in complex architectures. This controlled writing of patterns also presents a technique to create both masks at low temperatures for conductive multilayers as well as templates for electrospray deposition.

scholarly journals A Novel Approach to Design Chitosan-Polyester Materials for Biomedical Applications

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Tatiana A. Akopova ◽  
Tatiana S. Demina ◽  
Alexander N. Shchegolikhin ◽  
Tikhon S. Kurkin ◽  
Christian Grandfils ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Biomedical Applications ◽  
Oxidative Degradation ◽  
Shear Stresses ◽  
Chemical Transformations ◽  
Melting Points ◽  
Reactive Blending ◽  
Crystalline Polymers ◽  
Solid Polymers ◽  
Novel Approach

A novel approach to design chitosan-polyester materials is reported. The method is based on mechanical activation and effective intermixing of the substrates under high pressure and shear deformation in the course of solid-state reactive blending. The marked departure of this approach from previous practice resides on exploitation of a variety of chemical transformations of the solid polymers that become feasible under conditions of plastic flow. Low temperatures (aboveTgbut below the melting points of the crystalline polymers) are maintained throughout the process, minimizing mechanical and oxidative degradation of the polymers. Morphology as well as structural, mechanical, and relaxation properties of those prepared blends of chitosan with semicrystalline poly(L,L-lactide) and amorphous poly(D,L-lactide-co-glycolide) has been studied. Grafting of polyester moieties onto chitosan chains was found to occur under employed pressures and shear stresses. The prepared polymer blends have demonstrated an amphiphilic behavior with a propensity to disperse in organic solvents that widens possibilities to transform them into promising materials for various biomedical applications.

scholarly journals Analysis of Infra-Red Laser Power Process Using Response Surface Methodology

2016 ◽  
Vol 3 (2) ◽  
pp. 30-36
Author(s):  
Wahaizad Bin Safiei ◽  
Mohd Rashdan Bin Ab Rashid
Keyword(s):  
Response Surface Methodology ◽  
Laser Beam ◽  
Response Surface ◽  
Water Flow ◽  
Laser Power ◽  
Experimental Studies ◽  
Beam Size ◽  
Laser Marking ◽  
Ir Laser ◽  
Infra Red

High-quality products and shorten manufacturing lead time are very important factors addressed by many companies. Typically, low-quality products are induced by inconsistent of manufacturing process performance. To get a constant laser power in Infrared (IR) Laser Marking process was a common problem facing by many engineers in the manufacturing industry. This consequences might effect on laser marking characteristics such as the possibility of burn marking or blur marking particularly on the products. Therefore, the objective of this paper is to study the interaction between Infrared (IR) Laser Marking input parameters such as current (amp), frequency (Hz), water flow (l/min) and laser beam size (mm) on laser power (watt) as the main response. Furthermore, the response of laser power from Infra-Red laser process can be predicted when all combinations of parameters are tested. The IR marking machine was deployed and experimental studies were conducted in order to meet this objective. The experiments were based on Design of Experiment (DOE) and Response Surface Methodology (RSM) because second order model or polynomial equation was needed to fit for the response. The relationship between input and output parameters can be visualized by 3D graphs which were developed from Mathematical modeling. Based on the experiment results, the parameters that have significant effects on the laser power are current, laser beam size and water flow. However, frequency does not have a significant factor in this study.

Thermodynamic stability of clathrate hydrates relative to their separate chemical components

2003 ◽  
Vol 81 (1-2) ◽  
pp. 175-182 ◽  
Author(s):  
M A White ◽  
D C MacLaren ◽  
R A Marriott ◽  
B -Z Zhan
Keyword(s):  
Melting Point ◽  
Ethylene Oxide ◽  
Small Molecules ◽  
Low Temperatures ◽  
Experimental Information ◽  
Clathrate Hydrate ◽  
Clathrate Hydrates ◽  
Chemical Components ◽  
Melting Points ◽  
Guest Species

The thermodynamic changes (ΔH, ΔS, and ΔG) for the association of several small molecules (tetrahydrofuran (THF), ethylene oxide (EO), acetone) with water to form corresponding clathrate hydrates are calculated as a function of temperature from experimental information. For THF clathrate hydrate and EO clathrate hydrate at low temperatures, the clathrate is enthalpically stabilized with respect to the components. This is also the likely case for acetone clathrate hydrate. In all the three cases, above the melting points of the guest species, the clathrate increases in enthalpic stability, but entropic factors favour the separated components. Similar changes for THF clathrate hydrate and EO clathrate hydrate occur at the melting point of ice, eventually favouring the liquid components over the clathrate. PACS No.: 65.40-b

scholarly journals Optical investigation of crystallised nitrogen, argon, methane, and some of the simpler organic compounds, of low melting points

1912 ◽  
Vol 87 (596) ◽  
pp. 371-380 ◽  
Keyword(s):  
Thin Layer ◽  
Single Crystals ◽  
Organic Compounds ◽  
Low Temperatures ◽  
Glass Tube ◽  
Optical Methods ◽  
Optical Investigation ◽  
Melting Points ◽  
Thin Sections ◽  
Glass Plates

Nothing is known about the crystallographic properties of the elements gaseous at ordinary temperatures and of many of the most simply constituted organic bodies. As it is not probable that the preparation of well-developed single crystals, nor the measurement of such crystals by the methods now used for crystal measurements, would be successful, some observations on the solid forms of these bodies by crystallo-optical methods have been undertaken and will be described in this paper. The experimental difficulties are too great to permit of an investigation as complete as that which may be undertaken with substances crystallising at ordinary temperatures, but in spite of the fragmental character of the results obtained, they throw light upon the general crystallographic properties of these substances, and may for certain general purposes be sufficient. Methods of Investigation and Apparatus . Of the two methods employed at ordinary temperatures for crystallo-optical investigations, namely that of cutting thin sections of the crystal in certain directions, and that of allowing the substance to crystallise in a thin layer between a slide and a covering glass under the polarisation microscope, only the latter method can be adopted for work at low temperatures. As the gas has first to be condensed to a liquid between the glass plates, and has then to be crystallised, I first tried to obtain a suitable crystallisation vessel by blowing a small bulb on to a glass tube and squeezing the bulb flat while the glass was still soft.

Effect of laser power on conductivity and morphology of silver nanoparticle thin films prepared by a laser assisted electrospray deposition method

2021 ◽  
Vol 33 (1) ◽  
pp. 012034
Author(s):  
Pawan Pathak ◽  
Eduardo Castillo-Orozco ◽  
Ranganathan Kumar ◽  
Aravinda Kar ◽  
Hyoung J. Cho
Keyword(s):  
Thin Films ◽  
Silver Nanoparticle ◽  
Laser Power ◽  
Deposition Method ◽  
Electrospray Deposition

scholarly journals The Role of the Thermal Hysteresis Factor in Tenebrio Molitor Larvae

1978 ◽  
Vol 74 (1) ◽  
pp. 37-45 ◽  
Author(s):  
JEAN L. PATTERSON ◽  
JOHN G. DUMAN
Keyword(s):  
Relative Humidity ◽  
Low Temperatures ◽  
Thermal Hysteresis ◽  
Tenebrio Molitor ◽  
Short Photoperiod ◽  
Melting Points ◽  
Lethal Temperatures ◽  
Tenebrio Molitor Larvae ◽  
Better Than

The haemolymph of larvae of Tenebrio molitor contains a factor which produces a thermal hysteresis (a difference between the freezing and melting points) of approximately 0.75 °C. When larvae were acclimated to low temperatures or short photoperiod the thermal hysteresis increased more than twofold. Coincident with the increase in thermal hysteresis the supercooling points and lower lethal temperatures of the larvae were depressed. Therefore, the thermal-hysteresis-producing factor seems to function as an antifreeze. The factor may also act as an adaptation to prevent desiccation. Thermal hysteresis increased almost three-fold in larvae acclimated to low relative humidity. Also, larvae with high levels of the thermal hysteresis factor survived low relative humidities much better than did larvae with lower levels.

scholarly journals Investigation of the tensile properties of solid mercury and a comparison with those of other metals at low temperatures

1936 ◽  
Vol 156 (888) ◽  
pp. 411-426 ◽  
Keyword(s):  
Mechanical Properties ◽  
Melting Point ◽  
Tensile Properties ◽  
Low Temperatures ◽  
Atmospheric Temperature ◽  
Metals And Alloys ◽  
Melting Points ◽  
Experimental Procedure ◽  
Tension Tests

The mechanical properties of metals at temperatures approaching their melting points present a field of investigation which has not yet been adequately explored. Experimental procedure will vary according to the melting point of the metal. With the exception of mercury, all metals have a melting point considerably above atmospheric temperature. Mercury, however, freezes at —39⋅7° C and, on this account, it is comparatively easy to carry out tension tests at temperatures close to the melting point. The present investigation deals with the strength of mercury under such conditions and a comparison is made with several other metals and alloys at similar temperatures, namely, from 17° C to —130° C.

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