arXiv subjects

James D. Brownridge

Publications and source records attributed to James D. Brownridge.

17 recordsLinked to original sources

arXiv2025

Unraveling Specific Conditions for a Repeatable Mpemba Effect

Water exhibits many unique properties compared to other liquids, with some of these explained and others remaining enigmatic. Among them, it was proposed and extensively debated that hot water would freeze faster than cold water. Numerous studies have demonstrated the difficulty of successfully elucidating this effect, making explanations surrounding this phenomenon highly controversial. Here, we demonstrate that when two cups filled with cold and hot water are introduced simultaneously in a freezer saturated with ice-nucleating agents, the hot sample freezes faster and to a greater depth than the cold sample, particularly when the initial temperature difference is high. On the other hand, against some previous beliefs, the time to onset of crystallization is always and logically retarded for hotter samples. Under these conditions, where supercooling is eliminated and temperature recording is precisely controlled, robust experiments follow the same trend,regardless of whether hot versus room temperature (RT) samples or RT versus cold samples are tested.

physics.chem-ph↗

arXiv2015

Solar-induced thermal activity and stratification in pond water

Ponds are universally used to store water for a large number of uses. With the increasing demand for more fresh water, ponds, lakes and reservoirs are likely to be constructed on a larger scale. We must understand the effects of environmental changes on fresh water if we are to most efficiently utilize this resource. This study undertakes to increase our understanding of the rate of thermal response of ponds and other bodies of water to every-day environmental changes. The central research agenda is to investigate how the temperature of pond water from top to bottom responds to the day/night cycle, changes in air temperature just above the surface, cloud conditions, and other sudden environmental changes. Data collection for this study spanned October 2007 to June 2011 and had a continuous time resolution of 50 seconds.

physics.ao-ph↗

arXiv2011

Trees as Filters of Radioactive Fallout from the Chernobyl Accident

This paper is a copy of an unpublished study of the filtering effect of red maple trees (acer rubrum) on fission product fallout near Binghamton, NY, USA following the 1986 Chernobyl accident. The conclusions of this work may offer some insight into what is happening in the forests exposed to fallout from the Fukushima Daiichi Nuclear Plant accident. This posting is in memory of Noel K. Yeh.

physics.pop-ph↗

arXiv2011

Transitioning water to an enhanced heat-conducting phase

Water can be transitioned to an enhanced heat-conducting phase by supercooling only the water at the bottom of a container. The temperature gradient across the 4 cm in the center of an 8 cm long column of water with a 397 mW heat source at the top was lowered from 32oC to 0.75oC when the temperature at the bottom of the column was lowered from 1.2 oC to -5.6oC. The effective thermal conductivity of the water was increased from ~0.607 W/mK to ~24 W/mK. This result demonstrates that water has a high effective thermal conducting phase that has not been previously reported.

physics.flu-dyn↗

arXiv2010

A search for the Mpemba effect: When hot water freezes faster then cold water

An explanation for why hot water will sometime freeze more rapidly than cold water is offered. Two specimens of water from the same source will often have different spontaneous freezing temperatures; that is, the temperature at which freezing begins. When both specimens supercool and the spontaneous freezing temperature of the hot water is higher than that of the cold water, then the hot water will usually freeze first, if all other conditions are equal and remain so during cooling. The probability that the hot water will freeze first if it has the higher spontaneous freezing temperature will be larger for a larger difference in spontaneous freezing temperature. Heating the water may lower, raise or not change the spontaneous freezing temperature. The keys to observing hot water freezing before cold water are supercooling the water and having a significant difference in the spontaneous freezing temperature of the two water specimens. We observed hot water freezing before cold water 28 times in 28 attempts under the conditions described here.

physics.pop-ph↗

arXiv2008

Reduced heat flow in light water (H2O) due to heavy water (D2O)

The flow of heat, from top to bottom, in a column of light water can be decreased by over 1000% with the addition of heavy water. A column of light water cools from 25 C to 0 C in 11 hours, however, with the addition of heavy water it takes more than 100 hours. There is a concentration dependence where the cooling time increases as the concentration of added (D2O) increases, with a near maximum being reached with as little as 2% of (D2O) added. This phenomenon will not occur if the water is mixed after the heavy water is added.

cond-mat.soft↗

arXiv2008

Experimental Study of a Lorentz Actuated Orbit

This experimental study investigates a new technique to keep a satellite in orbit utilizing electrodynamics. The technique consists of establishing a charge on a satellite such that the body's motion through a planetary magnetic field induces acceleration via the Lorentz force. In order to find the relationship between capacitance and power required to balance incident plasma current, various objects were tested in high vacuum, plasma, and Xenon gas to determine their ability to hold charge. Radioactive material (Am-241) and pyroelectric crystals were tested as a candidate power source for charging the objects. Microscopic arcing was observed at voltages as low as -300 V. This arcing caused solder to explode off of the object. Insulating the object allowed the charge to remain on the object longer, while in the plasma, and also eliminated the arcing. However, this insulation does not allow a net charge to reside on the surface of the spacecraft.

physics.plasm-ph↗

arXiv2008

Anomalous Effects in Air While Cooling Water

Water is a unique compound with many anomalies and properties not fully understood. Designing an experiment in the laboratory to study such anomalies, we set up a series of experiments where a tube was placed inside a sealed container with thermocouples attached to the outer surface of the tube and in the air adjacent to the tube. Alternately, deionized water and other compounds were added to the tube and cooled to freezing. Several of the thermocouples suspended in the air and adjacent to the tube showed thermal oscillations as the overall temperature of the container was decreasing. The temperature of the thermocouples increased and decreased in a sinusoidal way during part of the cool down to freezing. Thermal oscillations as large as 3 degrees Celsius were recorded with typical frequencies of about 5 oscillations per minute.

physics.chem-ph↗

arXiv2008

Investigation of the Vertical Movement of an Isothermal Line at the Density Maximum in H2O and D2O

We studied the cooling of a column of water, primarily in a freezer, and analyzed the development and movement of an isothermal line at ~4 degC in H2O and ~11 degC in D2O. Our experiments show that the vertical velocity of the symmetrical isothermal line moving up the column of water is inversely proportional to the diameter of the column of water. It has a measured maximum velocity of 1.4 +/- 0.1 cm/min when the column diameter is 22 mm and decreases to 0.4 +/- 0.1 cm/min when the diameter is increased to 125 mm. The measurement of the velocity becomes increasingly difficult to obtain when the column diameter is less than 22 mm because of the lack of complete development of the isothermal line. The data and discussion presented in this paper raise serious questions to the claim of new phase transitions in water made by S. Esposito, et. al. 0704.1381

physics.chem-ph↗

arXiv2004

Using Static Charge on Pyroelectric Crystals to Produce Self Focusing Electron and Ion Beams and Transport Through Tubes

Static charge in and on the surface of pyroelectric crystals of LiNbO3 and LiTaO3 in a dilute gas has been shown to ionize gas molecules via electron tunneling. The released electrons and positive ions are focused and accelerated according to the sign of the static uncompensated charge. The uncompensated charge is produced when the temperature of the crystal is changed from any initial temperature between about 500K and about 15K. It may be either polarization charge that is inside the crystal surface or compensation charge that is on the surface. The direction of temperature change and the polarity of the base of the crystal determine whether electrons or positive ions are accelerated toward or away from the crystal. The ionization, focusing and acceleration may continue for more than 15 days following a single change in temperature.

physics.atm-clus↗

arXiv2003

X-ray fluoresced high-Z (up to Z = 82) K-x-rays produced by LiNbO3 and LiTaO3 pyroelectric crystal electron accelerators

High-energy bremsstrahlung and K X-rays were used to produce nearly background-free K X-ray spectra of up to 87 keV (Pb) via X-ray fluorescence. The fluorescing radiation was produced by electron accelerators, consisting of heated and cooled cylindrical LiTaO3 and LiNbO3 crystals at mTorr pressures. The newly discovered process of gas amplification whereby the ambient gas pressure is optimized to maximize the electron energy was used to produce energetic electrons which when incident on a W/Bi target gave rise to a radiation field consisting of high-energy bremsstrahlung as well as W and Bi K X-rays. These photons were used to fluoresce Ta and Pb K X-rays.

physics.ins-det↗

arXiv2003

Polar Concentration of Elements in Tree Leaves

A long-term study of the elements Mg, Al, Si, P, Ca, S, Cl, Fe and Mn in leaves is in progress. The objective of this study is to develop a week-by-week profile of these elements in leaves during several growing seasons. The profile includes the following information: (1) Which elements each tree collects in its leaves. (2) The location in the leaf with the highest concentration, top side, under side or interior. (3) The week during the growing season when each element first appears in the leaves of each tree. (4) The change in the relative concentration from week to week. (5) The source of the element i.e., deposition from the atmosphere or the root system of the tree. This information is profile for each year and will be correlated with environmental conditions for that year. Leaves are collected weekly from first unfolding in early spring until leaf drop in the fall. They are from the 31 trees and 26 species in Broome County, NY. From time to time leaves from most of the 26 species are being randomly collected from trees growing throughout the northeastern US.

physics.bio-ph↗

arXiv2003

Saturation of Spontaneous Polarization Charge in Pyroelectric Crystals of LiNbO3, LiTaO3 and CsNO3 at Low Temperature Above 4.2 K

Experimental observations of the change in the polarization charge of pyroelectric crystals of LiNbO3, LiTaO3 and CsNO3, as the temperature of the crystal is changed from about 300K to a lower limit of 4.2K, are described. It was found that the rate of change of the polarization charge slowed down considerably and, perhaps, reached a zero rate of change. The onset of this saturation of the polarization charge occurred at low temperatures, above the temperature of liquid helium, which were different for each of the three types of crystal.

cond-mat.mtrl-sci↗

arXiv2003

Pressure Dependence of Energetic (160 keV) Focused Electron Beams Arising From Heated or Cooled (LiNbO3) Pyroelectric Crystals

A new effect, gas amplification of electron energy is reported here; namely when a cylindrical pyroelectric crystal such as (LiNbO3) is contained in a concentric cylindrical chamber and is heated and then allowed to cool in a dilute gas the maximum energy of the resultant focused electron beam more than doubles as the pressure increases from 0.05 to 4 mTorr for seven different gases.

physics.atom-ph↗

arXiv2002

Electron Beam Production by Pyroelectric Crystals

Pyroelectric crystals are used to produce self-focused electron beams with energies greater than 170 keV. No high voltage power supply or electron gun is needed. The system works by simply changing the temperature of a crystal of LiNbO3 or LiTaO3 by about 100oC in dilute gas. Electron beam energy spectra as well as positive-ion-beam energy spectra and profiles are shown. A change in the crystal temperature of 100oC will cause a spontaneous change in polarization. The change in polarization will be manifested by a change in charge on the surface of the crystal. It is this uncompensated charge that produces the electric field, which accelerates the electrons, or the positive ions and gives rise to the plasma, which in turn focuses them. The source of the accelerated electrons or positive ions is gas molecules ionized near the crystal surface. When the crystal surface is negative electrons are accelerated away from it and positive ions are attracted to the surface. These positive ions reduce the net negative charge on the surface thereby reducing the electric field, which causes the electron energy to decrease over time even though the focal properties remain unchanged. When the surface is positive the reverse obtains and the positive ion beam energy decreases over time as well. We will present video clips, photographic and electronic data that demonstrate many of the characteristics and applications of these electron beams.

physics.plasm-ph↗

arXiv2002

Electrical Indicator of Imminent Freezing in Supercooled Water

Data is presented that demonstrate electrical activity and evidences of dipole alignment in supercooled water and heavy water before and after the onset of freezing. Voltage signals as high as 13 mV have been recorded. In some cases up to 3 seconds before latent heat is released and freezing began. The polarity of the voltage signals is suggestive of molecule dipole alignment prior to freezing.

physics.gen-ph↗

arXiv2001

Pyroelectric Response in LiNbO3 and LiTaO3 to Temperature Changes

Measurements of the polarization charge accumulated at the -z and the +z bases of the pyroelectric crystals of LiNbO3 and LiTaO3 during changes in temperature are described. An electrometer in the charge mode with its probe attached to the base under study was used. A reference for the electrometer was established by grounding the electrometer probe at a specific crystal temperature, i.e., zeroing the electrometer. When the ground is broken an induced charge, held captive by the polarization charge at the base of the crystal, remains in the probe circuit. Then as the temperature of the crystal is changed the electrometer reads the change in the polarization charge with respect to the polarization charge at the zeroing temperature. Data was obtained for each type of crystal and at the -z and +z bases for three different grounding conditions. Each experiment consisted of data accumulation for five thermal cycles. The electrometer readings at a given temperature appeared to be different for the three grounding conditions but the difference in the charge readings for a given difference of temperature was independent of the grounding situation. Measurements of the polarization charge were taken while the temperature of the crystal was held constant for about fourteen hours. The polarization charge remained constant at the -z and +z base as long as the temperature remained constant. These results, the independence of the charge difference for a given temperature difference with respect to the zeroing conditions and the constancy of the charge reading with respect to the constancy of the crystal temperature, lead to the inference that the polarization charge is a reproducible function of the crystal temperature and is a physical property of the crystal.

physics.atm-clus↗