Temperature-induced Variation Research Articles

WDM-based radio frequency dissemination in a tree-topology fiber optic network.

In this paper, we propose and demonstrate a scheme to achieve point-to-multipoint dissemination of radio frequency (RF) signals in a local area fiber optic network with tree topology based on wavelength-division multiplexing (WDM) technique. The phase changes caused by the fluctuations of the transfer links are passively canceled at remote end instead of at local end, which makes it feasible to flexibly build a tree-topology local area dissemination network with great cost-effectiveness. For the first time, we study the limit of long-term performance which is caused by temperature-induced variation of group velocity dispersion (TIVGVD) in dissemination networks using WDM techniques. In the proof-of-concept experiments, 38.5 km and 50 km fiber links are established to disseminate a 1 GHz frequency signal with fractional instability of 10(-17) order after 10(4) s averaging time. Then 17.4 nm wavelength spacing is introduced between local carrier and user carrier to verify the theoretical analysis. Under a controlled fiber temperature variation of about 21 °C, the obtained overlapping Allan deviation (ADEV) agrees well with the simulation results after 10(4) s time scales, which proves the validity of our theory. The theory has practical values in predicting and optimizing the capacity and performance of a WDM-based local area RF dissemination network.

Temperature-induced variation of magnetoresistance and tunneling current in La2/3Sr1/3MnO3/LaMnO3 (ZrO2)/La2/3Sr1/3MnO3 junctions

Abstract We report the temperature dependence of the magnetotransport properties for the La 2/3 Sr 1/3 MnO 3 /ZrO 2 /La 2/3 Sr 1/3 MnO 3 and La 2/3 Sr 1/3 MnO 3 /LaMnO 3 /La 2/3 Sr 1/3 MnO 3 trilayer junctions. The ferromagnetic La 2/3 Sr 1/3 MnO 3 has been selected as the top and bottom ferromagnetic metallic layers, along with the antiferromagnetic LaMnO 3 spacer and nonmagnetic ZrO 2 spacer as tunneling barriers, respectively. For different tunneling barriers, the magnetoresistance and the tunneling current of the junctions show different phenomena with decreasing temperature. Temperature dependence of magnetoresistance of the La 2/3 Sr 1/3 MnO 3 /ZrO 2 /La 2/3 Sr 1/3 MnO 3 structure shows double peaks while that of La 2/3 Sr 1/3 MnO 3 /LaMnO 3 /La 2/3 Sr 1/3 MnO 3 displays one peak. Furthermore, the tunneling current is correlated with the magnetoresistance. These findings may find potential uses in magnetic data storages and magnetic switches.

Assessment of temperature-induced hERG channel blockade variation by drugs.

Drug-induced QT prolongation has been reported in humans and animals. This potentially lethal effect can be induced by drugs interacting with a cardiac potassium channel, namely hERG (human ether-a go-go-related gene) leading to arrhythmia or torsade de pointes (TdP). Hence, in vitro evaluation of therapeutics for their effects on the rapid delayed rectifier current (IKr) mediated by the K(+) ion channel encoded by hERG is a valuable tool for identifying potential arrhythmic side effects during drug safety testing. Our objective was to evaluate the temperature-induced hERG channel blockade variation by human and veterinary drugs using the IonFlux 16 system. A panel of eight drugs was tested for IKr inhibition at both ambient (23 °C) and physiological (37 °C) temperatures at various concentrations using IonFlux 16, an automated patch clamp system. Our results established that both amiodarone (IC(50) = 0.56 μM at 23 °C and 0.30 μM at 37 °C) and β-estradiol (IC(50) = 24.72 μM at 23 °C and 8.17 μM at 37 °C) showed a dose-dependent IKr blockade with a higher blockade at 37 °C. Whereas, blockade of IKr by both ivermectin (IC(50) = 12.52 μM at 23 °C and 24.41 μM at 37 °C) and frusemide (IC(50) = 12.58 μM at 23 °C and 25.55 μM at 37 °C) showed a dose-dependent IKr blockade with a lower blockade at 37 °C. Gentamicin, enrofloxacin, xylazine and albendazole did not block IKr at both the assessed temperatures. Collectively, these results demonstrate that the effect of temperature variation should be taken into consideration during the evaluation of test drugs for their hERG channel blockade potential.

Temperature-induced variation in the survival of brooded embryos drives patterns of recruitment and abundance in Semibalanus balanoides

Geographic distributions of species are frequently influenced by temperature and as a result, there is considerable interest in predicting the effect of climate change on biogeography. Previous studies have found strong correlations between sea surface temperature and recruitment in the acorn barnacle Semibalanus balanoides, an important member of temperate intertidal communities in the Northern Hemisphere. The underlying mechanism that drives this relationship is, however, unknown. The hypothesis tested here is that variation in recruitment is determined by temperature-induced variation in survival of brooded embryos.Brooding adults were held under several environmentally-relevant temperature conditions from 7°C to 13°C until eggs were ready to hatch. There was no significant effect of temperature on embryonic development rate. Brooding individuals held at colder temperatures had more than twice the reproductive mass of those held at warmer temperatures. This mass difference is caused by an over three-fold larger number of embryos surviving in the coldest treatment (7°C) compared to the warmest treatment (13°C). Temperature-induced variation in number of surviving embryos likely contributes to differences in recruitment following cold winters vs. warm winters. Such temperature-dependent variation in recruitment has been shown to cause year to year fluctuations in the positions of the geographic limits of the species in Southwest England, France, and Spain. This study illustrates the key role of adult input into the larval pool in generating variation in recruitment and its influence on biogeography.

Structure, Luminescence, and Two-Dimensional Correlation Infrared Spectroscopy of Two Sm/3-Methylbenzoic Acid Complexes

Two samarium complexes with 3-methylbenzoic acid (HMeBA = 3-methylbenzoic acid) have been hydrothermally synthesized directly: Sm(MeBA)3 1 and Sm2(MeBA)6(o-Phen)2 2 (o-Phen = o-phenanthroline). 1 is a one-dimensional helical chain structure. In particular, due to the existence of the second ligand-o-Phen, which includes three aromatic rings and has very large steric hindrance, 2 is a zero-dimensional binuclear oligomer and is further assembled into an infinite chain, two-dimensional net and three-dimensional supramolecular structure by the weak interactions of π–π and C-H···π. Additionally, in order to explore the structural characteristic, luminescence and 2D-IR correlation spectroscopy containing temperature-induced structural variation and magnetism-induced structural variation are used. Supplementary material is available for this article. Go to the publisher's online edition of Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry to view the supplemental file.

Do fluctuations in incubation temperature affect hatchling quality in the Chinese soft-shelled turtle Pelodiscus sinensis?

The Chinese soft-shelled turtle Pelodiscus sinensis is the most common turtle species sold in China. In most turtle farms P. sinensis eggs are incubated at fluctuating temperatures. To examine if fluctuations in incubation temperature affect hatching success, incubation length and hatchling quality, we incubated P. sinensis eggs in five incubators: one set at 30°C, two ramp-programmed at 30±3°C and±5°C; the remaining two step-programmed at 30±3°C and±5°C. Temperatures changed at 12h (+) and 12h (−) in the ramp-programmed incubators, and at 6h intervals in an order of lowest–mean–highest–mean levels in the step-programmed incubators. Size-related (carapace length, carapace width and mass) rather than performance-related (swimming speed and early growth) hatchling phenotypes differed among the five treatments. Eggs in ramp-programmed incubators overall produced larger hatchlings than did those in step-programmed incubators, and eggs at 30°C produced larger hatchlings than did those incubated at fluctuating temperatures. However, temperature-induced variation in hatchling size was not a significant source of variation in post-hatching growth, and the pattern of fluctuations in incubation temperature was less important for turtles reared in the laboratory. We suggest that the most important thing that should be done by farmers is to avoid exposure of P. sinensis eggs to the temperatures potentially lethal to embryos rather than to incubate them at stable temperatures.

Turnover Temperature Point in Extensional-Mode Highly Doped Silicon Microresonators

This paper demonstrates the existence of a local zero temperature coefficient of frequency (i.e., turnover point) in extensional-mode silicon microresonators, fabricated on highly n-type-doped substrates and aligned to the [100] crystalline orientation. It is shown through both theoretical analysis and finite-element simulation that the turnover point in thin-film piezoelectric-on-silicon (TPoS) resonators is a function of doping concentration and orientation. Moreover, the turnover point can be adjusted by changing the thickness ratio of Si and the piezoelectric film (e.g., AlN) in the resonant structure. In order to experimentally validate this result, similar resonators are fabricated on silicon-on-insulator substrates, and the temperature variation of frequency is measured. An overall temperature-induced frequency variation of less than 245 ppm is measured over the range of -40 °C-85 °C for an ~ 25-MHz TPoS resonator aligned to the [100] plane. This is more than a 15-times reduction with respect to the uncompensated conventional silicon resonators reported before. This work is a significant step toward strengthening silicon's position as an alternative resonator technology in the quartz-dominated stable oscillator market.

A Temperature-to-Digital Converter for a MEMS-Based Programmable Oscillator With <formula formulatype="inline"> <tex Notation="TeX">$< \pm \hbox{0.5-ppm}$</tex></formula> Frequency Stability and <formula formulatype="inline"><tex Notation="TeX">$< \hbox{1-ps}$</tex></formula> Integrated Jitter

MEMS-based oscillators offer a silicon-based alternative to quartz-based frequency references. Here, a MEMS-based programmable oscillator is presented which achieves better than ±0.5-ppm frequency stability from -40 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> C to 85 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> C and less than 1-ps (rms) integrated phase noise (12 kHz to 20 MHz). A key component of this system is a thermistor-based temperature-to-digital converter (TDC) which enables accurate and low noise compensation of temperature-induced variation of the MEMS resonant frequency. The TDC utilizes several circuit techniques including a high-resolution tunable reference resistor based on a switched-capacitor network and fractional-N frequency division, a switched resistor measurement approach which allows a pulsed bias technique for reduced noise, and a VCO-based quantizer for digitization of the temperature signal. The TDC achieves 0.1-mK (rms) resolution within a 5-Hz bandwidth while consuming only 3.97 mA for all analog and digital circuits at 3.3-V supply in 180-nm CMOS.

Far-infrared spectra of the magnetic exchange resonances and optical phonons and their connection to magnetic and dielectric properties of Dy3Fe5O12garnet

Far-infrared spectra of ferrimagnetic Dy${}_{3}$Fe${}_{5}$O${}_{12}$ single crystals have been studied in the spectral range between 12 and 700 cm${}^{\ensuremath{-}1}$ and in a wide temperature range between 5 K and 300 K using transmission spectroscopy and rotating analyzer ellipsometry. In the temperature range below ${T}_{C}$ = 16 K for the magnetic ordering of Dy${}^{3+}$ spins, a number of ligand field and Kaplan-Kittel (KK) exchange resonance modes have been found. Temperature dependencies of their frequencies allowed us to estimate the ratio between the Fe-Dy and Dy-Dy exchange constants. We found that variation of the oscillator strength of the KK modes correlates with the magnetic-field-induced changes of magnetic permeability. The low-temperature peak in the static value of the dielectric function at ${T}_{C}$ = 16 K may be related to the observed temperature-induced variation of the oscillator strength of the optical phonons.

Use of temperature dependent Raman spectra to improve accuracy for analysis of complex oil-based samples: Lube base oils and adulterated olive oils

A simple and effective strategy to improve accuracy for Raman spectroscopic analysis of complex mixture samples by probing a measurement temperature yielding enhanced spectral selectivity has been demonstrated. For the evaluation, the determination of Kinematic Viscosity at 40°C (KV@40) of lube base oil (LBO) samples was initially attempted. Partial least squares (PLS) was used to determine the KV@40 using Raman spectra of the samples collected at 8 different temperatures from 20 to 90°C with 10°C increments. Interestingly, the distinct temperature-induced spectral variation among the samples occurred at 50°C, thereby resulting in the improved accuracy for determination of KV@40. Two-dimensional (2D) correlation analysis was also performed to find an additional supportive rationale for the improved accuracy. The strategy was further evaluated for the identification of soybean oil-adulterated olive oils using linear discriminant analysis (LDA). Similarly, the discrimination accuracy was improved around 80–90°C due to the enhanced spectral selectivity between olive and soybean oils. In overall, these two results successfully demonstrate analytical effectiveness of the strategy.

Widespread reproductive variation in North American turtles: temperature, egg size and optimality

Theory predicts the existence of an optimal offspring size that balances the trade-off between offspring fitness and offspring number. However, in wild populations of many species, egg size can still vary from year to year for unknown reasons. Here, we hypothesize that among-year variation in population mean egg size of freshwater turtles is partly a consequence of their gonadal sensitivity to seasonal temperatures, a physiological mechanism which principally functions to synchronize reproduction with a favorable time of year. As part of this process, among-year variation in seasonal temperatures modifies the extent of egg follicle development, and this may translate into variation in mean egg size among years (both at the individual and population level). To test this hypothesis, we applied an information-theoretic approach to model relationships between mean egg mass and the temperatures experienced during discrete periods of follicular development in wild populations of three turtle species (Chrysemys picta, Chelydra serpentina, Glyptemys insculpta) over 12 consecutive years. Because follicular development occurs in the fall for C. serpentina and G. insculpta, whereas it occurs both in the fall and spring for C. picta, we expected only fall temperatures would explain egg size variation in C. serpentina and G. insculpta, whereas both fall and spring temperatures would correlate with egg size variation in C. picta. These predictions were upheld. We then compared among-year variation in within-female egg and clutch sizes of each species in order to evaluate whether such variation might still be consistent with some tenets of optimal egg size theory. In all three species, we found that clutch sizes vary more than egg sizes in spite of temperature-induced egg size variation, and this pattern of relatively high clutch-size variation matches theoretical predictions. Future work should explore the roles of direct and indirect (i.e., nutritional) influences of temperature on egg size in natural settings.

A novel stress isolation guard-ring design for the improvement of a three-axis piezoresistive accelerometer

This study designs and implements a stress isolation guard-ring structure to improve the performances of the existing single proof-mass three-axis piezoresistive accelerometer. Thus, the environment disturbances, such as temperature variation and force/deflection transmittance, for a packaged three-axis piezoresistive accelerometer are significantly reduced. In application, the three-axis piezoresistive accelerometer has been fabricated using the bulk micromachining process on the SOI wafer. Experimental results show that the out-of-plane deformation of the suspended spring mass on the packaged accelerometer is reduced from 0.72 to 0.10 µm at a 150 °C temperature elevation. The temperature coefficient of zero-g offset for the presented sensor is reduced, and the temperature-induced sensitivity variation is minimized as well. Measurements also demonstrate that the guard-ring design successfully reduces the false signals induced by the force and displacement transmittance disturbances for one order of magnitude. Moreover, the three-axis acceleration sensing for the presented accelerometer with guard ring has also been demonstrated with sensitivities of 0.12–0.17 mV V−1 g−1 and nonlinearity < 1.02%.

Toxin production and temperature-induced morphological variation of the diatom Pseudo-nitzschia seriata from the Arctic

This is the first record of a domoic acid-producing organism from polar waters. Strains of the cold-water diatom Pseudo-nitzschia seriata were isolated from water samples collected from the west coast of Greenland. Growth experiments on two of the strains showed similar growth rates at 4 °C and production of DA (domoic acid) and the two isomers IA (isodomoic acid A) and IB (isodomoic acid B). Both strains produced significantly higher amounts of DA than of IA and IB. The concentrations of domoic acids were 1.46–1.93 pg per cell, and thus have the potential to pose a risk for amnesic shellfish poisoning. Four strains of P. seriata were cultured at different temperatures (4, 10 and 15 °C), and morphological differences were found at the different temperatures. Similar differences have been observed previously in field samples from different geographical areas and have resulted in uncertainty regarding the taxonomy of P. seriata and related species. Transmission electron microscopy showed that at 4 °C the strains corresponded to the original description of P. seriata. At higher temperatures, the number of rows of poroids in the striae as well as the density of poroids decreased, and cells then resembled the closely related P. australis. The Greenlandic strains of P. seriata did not grow well at 15 °C. The identity of the strains was confirmed by analyses of ITS1, 5.8S and ITS2 rDNA from P. seriata and P. australis, using strains from different geographical areas. There was a close phylogenetic relationship between P. seriata and P. australis but the analyses demonstrated consistent molecular differences between the two species, in spite of the morphological similarity.

Bryozoan growth and environmental reconstruction by zooid size variation

The modular growth of cheilostome bryozoans combined with temperature-induced variation in module (zooid) size has enabled the development of a unique proxy for deducing sea- sonal temperature regimes. The approach is based on measures of intracolonial variation in zooid size that can be used to infer the mean annual range of temperature (MART) experienced by a bryozoan colony as predicted by a model of this relationship that was developed primarily to infer palaeosea- sonal regimes. Using the model predictions effectively requires a highly strategic approach to char- acterise the relative amount of within-colony zooid size variation (by adopting random or very sys- tematic measurements of zooids that meet a stringent set of criteria) to gain insights on temperature variation. The method provides an indication of absolute temperature range but not the actual tem- peratures experienced. Here we review the development of, support for and applications of the zooid size MART approach. In particular, we consider the general issue of why body size may vary with temperature, studies that validate the zooid size-temperature relationship and insights that have been gained by application of the zooid size MART approach. We emphasise the potential limitations of the approach, including the influence of confounding factors, and highlight its advantages relative to other proxies for palaeotemperature inferences. Of prime importance is that it is relatively inex- pensive and quick and allows a direct estimate of temperature variation experienced by an individ- ual colony. Our review demonstrates a strong and growing body of evidence that the application of the zooid size MART approach enables robust interpretations for palaeoclimates and merits broad recognition by environmental and evolutionary biologists and climate modellers.

Fish age at maturation is influenced by temperature independently of growth

Age and size at maturation are important correlates of fitness in many organisms and understanding how these are influenced by environmental conditions is therefore required to predict populations' responses to environmental changes. In ectotherms, growth and maturation are closely linked to temperature, but nonetheless it is often unclear how temperature-induced variation in growth and temperature per se translate to the process of maturation. Here, we test this explicitly with a common garden experiment using nine-spined sticklebacks (Pungitius pungitius). We reared fish in 14 and 17°C and recorded high resolution growth trajectories and the timing of maturation on an individual basis. To characterize the growth of each individual, we fitted a von Bertalanffy growth curve to each measured growth trajectory, so that the three parameters of the curve provided a summary of an individual's growth. Temperature treatments induced changes in both the growth parameters and the age at maturation. In females, changes in the age of maturation were encompassed by variations in growth, whereas in males there was a temperature-related shift in the age at maturation that was unrelated to growth. Our experiment demonstrates that temperature can affect maturation directly, and not only through temperature-induced changes in growth. Therefore, one cannot predict, on the basis of growth only, how changes in temperature might alter age and size at maturation and the subsequent reproduction.

Sexual size dimorphism decreases with temperature in a blowfly, Chrysomya megacephala (Fabricius) (Diptera: Calliphoridae)

1. There is wide intra-specific variation in sexual size dimorphism (SSD). Much of this variation is probably as a result of sexual differences in the selective pressure on body size. However, environmental variables could affect males and females differently, causing variation in SSD. 2. We examined the effects of two temperatures (20 and 30 °C) on SSD in six populations of the blowfly, Chrysomya megacephala. 3. We found that body size increased with temperature in all the populations studied, and the sexes differed in phenotypic plasticity of body size in response to rearing temperature. This created substantial temperature-induced variation in SSD (i.e. sex × temperature interaction). Males were often smaller than females, but the degree of dimorphism was smaller at the higher temperature (30 °C) and larger at the lower temperature (20 °C). This change in SSD was not because of a gender difference in the effect of temperature on development time. Further studies should address whether this variation can be produced by adaptive canalisation of one sex against variation in temperature, or whether it may be a consequence of non-adaptive developmental differences between the sexes. 4. Although most studies assume that the magnitude of SSD is fixed within a species, the present study demonstrates that rearing temperature can generate considerable intra-specific variation in the degree of SSD.

Magnetic structures ofδ-O2resulting from competition of interplane exchange interactions

Solid oxygen is a unique molecular crystal whose phase diagram is mostly imposed by magnetic ordering, i.e., each crystal phase has a specific magnetic structure. However, recent experiments showed that high-pressure $\delta$-phase is implemented in different magnetic structures. In the present paper we study the role of interplane exchange interactions in formation of the magnetic structures with different stacking sequences of the close-packed planes. We show that temperature-induced variation of intermolecular distances can give rise to compensation of the exchange coupling between the nearest close-packed planes and result in the phase transition between different magnetic structures within $\delta$-O$_2$. Variation of the magnetic ordering is, in turn, accompanied by the step-wise variation of interplane distance governed by space and angular dependence of interplane exchange constants.

An application of concatenated 2D correlation spectroscopy: Exploration of the reversibility of the temperature-induced hydration variation of poly( N-isopropylmethacrylamide) in aqueous solution

We have demonstrated an application of “concatenated” 2D correlation analysis in quantitative or semi-quantitative examination of the reversibility of the temperature-induced hydration variation of PNiPMA in water solution. Hydration reversibility of hydrophilic amide group and hydrophobic CH group are compared in different temperature ranges. The appearance of significant cross-peaks in the asynchronous spectrum calculated from the roundtrip data matrix indicates the existence of certain inter-asynchronicity between heating and cooling cycle. The contribution of different factors to the 2D asynchronous spectrum could be separated by selecting the range of the spectral dataset for concatenation. The irreversibility of the temperature-induced hydration variation in PNiPMA is not constant during the whole round trip: it is most obvious in the phase separation process, while in the range far away from that period it is nearly neglectable. The hydration variation of PNiPMA manifests significant irreversibility in the phase separation stage. The asynchronous peaks of hydrophobic CH groups are much weaker than that of hydrophilic amide group during any temperature range in the temperature round trip. The irreversibility of CH groups is not as strong as that of amide group during the round trip. It further supports the conclusion that the hydration variation of hydrophilic amide group is dominated in the temperature-induced phase separation of the polymer in water solution.

Numerical simulation of hydrogen atom transport in thick nickel membrane using semi-empirical quantum model

The transport characteristics of hydrogen atoms are of significant interest within the energy industry. In this study, molecular dynamics (MD) simulations based on a semi-empirical quantum model are performed to examine the diffusion of hydrogen in a dense nickel membrane. The mean square displacement (MSD) and diffusion coefficients of the nickel and hydrogen atoms are derived at various temperatures in the range of 300–1800 K. The numerical results reveal the changes which take place in the transportation mechanism of the hydrogen atoms as a result of a temperature-induced variation in the lattice structure. It is shown that the transport of the hydrogen atoms changes from an interstitial diffusion mechanism at temperatures lower than 1200 K to a vacancy diffusion mechanism at temperatures of 1600–1800 K as result of a change in the nickel lattice from an ordered FCC structure to an amorphous-type structure.

Effects of temperature on the protective property, structure and composition of the oxide film on Alloy 625

The paper mainly investigated the protective property, structure and composition of the oxide film on Alloy 625 in a lithium borate buffer solution (pH 300°C = 6.93) in the temperature range of 25–300 °C. The methods used were electrochemical measurements and XPS analysis. As temperature increased, the protective property of the oxide film degraded, and the structure varied from a singe-layer to double-layer. The oxide film consisted of Cr 2O 3 and Cr(OH) 3 at 25 and 150 °C, while it contained Ni(OH) 2, in addition to Cr 2O 3 and Cr(OH) 3 at 250 and 300 °C. This was mainly attributed to the temperature-induced variation of composition and protective property of the barrier layer.