Conformational variation of proteins at room temperature is not dominated by radiation damage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russi, Silvia; González, Ana; Kenner, Lillian R.

Protein crystallography data collection at synchrotrons is routinely carried out at cryogenic temperatures to mitigate radiation damage. Although damage still takes place at 100 K and below, the immobilization of free radicals increases the lifetime of the crystals by approximately 100-fold. Recent studies have shown that flash-cooling decreases the heterogeneity of the conformational ensemble and can hide important functional mechanisms from observation. These discoveries have motivated increasing numbers of experiments to be carried out at room temperature. However, the trade-offs between increased risk of radiation damage and increased observation of alternative conformations at room temperature relative to cryogenic temperature havemore » not been examined. A considerable amount of effort has previously been spent studying radiation damage at cryo-temperatures, but the relevance of these studies to room temperature diffraction is not well understood. Here, the effects of radiation damage on the conformational landscapes of three different proteins ( T. danielli thaumatin, hen egg-white lysozyme and human cyclophilin A) at room (278 K) and cryogenic (100 K) temperatures are investigated. Increasingly damaged datasets were collected at each temperature, up to a maximum dose of the order of 10 7 Gy at 100 K and 10 5 Gy at 278 K. Although it was not possible to discern a clear trend between damage and multiple conformations at either temperature, it was observed that disorder, monitored by B-factor-dependent crystallographic order parameters, increased with higher absorbed dose for the three proteins at 100 K. At 278 K, however, the total increase in this disorder was only statistically significant for thaumatin. A correlation between specific radiation damage affecting side chains and the amount of disorder was not observed. Lastly, this analysis suggests that elevated conformational heterogeneity in crystal structures at room temperature is observed despite radiation damage, and not as a result thereof.« less

Nanoindentation study of bulk zirconium hydrides at elevated temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cinbiz, Mahmut Nedim; Balooch, Mehdi; Hu, Xunxiang

Here, the mechanical properties of zirconium hydrides was studied using nano-indentation technique at a temperature range of 25 – 400 °C. Temperature dependency of reduced elastic modulus and hardness of δ- and ε-zirconium hydrides were obtained by conducting nanoindentation experiments on the bulk hydride samples with independently heating capability of indenter and heating stage. The reduced elastic modulus of δ-zirconium hydride (H/Zr ratio =1.61) decreased from ~113 GPa to ~109 GPa while temperature increased from room temperature to 400°C. For ε-zirconium hydrides (H/Zr ratio=1.79), the reduced elastic modulus decreased from 61 GPa to 54 GPa as temperature increased from roommore » temperature to 300 °C. Whereas, hardness of δ-zirconium hydride significantly decreased from 4.1 GPa to 2.41 GPa when temperature increased from room temperature to 400 °C. Similarly, hardness of ε-zirconium hydride decreased from 3.06 GPa to 2.19 GPa with temperature increase from room temperature to 300°C.« less

Nanoindentation study of bulk zirconium hydrides at elevated temperatures

DOE PAGES

Cinbiz, Mahmut Nedim; Balooch, Mehdi; Hu, Xunxiang; ...

2017-08-02

Here, the mechanical properties of zirconium hydrides was studied using nano-indentation technique at a temperature range of 25 – 400 °C. Temperature dependency of reduced elastic modulus and hardness of δ- and ε-zirconium hydrides were obtained by conducting nanoindentation experiments on the bulk hydride samples with independently heating capability of indenter and heating stage. The reduced elastic modulus of δ-zirconium hydride (H/Zr ratio =1.61) decreased from ~113 GPa to ~109 GPa while temperature increased from room temperature to 400°C. For ε-zirconium hydrides (H/Zr ratio=1.79), the reduced elastic modulus decreased from 61 GPa to 54 GPa as temperature increased from roommore » temperature to 300 °C. Whereas, hardness of δ-zirconium hydride significantly decreased from 4.1 GPa to 2.41 GPa when temperature increased from room temperature to 400 °C. Similarly, hardness of ε-zirconium hydride decreased from 3.06 GPa to 2.19 GPa with temperature increase from room temperature to 300°C.« less

Room-temperature processed tin oxide thin film as effective hole blocking layer for planar perovskite solar cells

NASA Astrophysics Data System (ADS)

Tao, Hong; Ma, Zhibin; Yang, Guang; Wang, Haoning; Long, Hao; Zhao, Hongyang; Qin, Pingli; Fang, Guojia

2018-03-01

Tin oxide (SnO2) film with high mobility and good transmittance has been reported as a promising semiconductor material for high performance perovskite solar cells (PSCs). In this study, ultrathin SnO2 film synthesized by radio frequency magnetron sputtering (RFMS) method at room temperature was employed as hole blocking layer for planar PSCs. The room-temperature sputtered SnO2 film not only shows favourable energy band structure but also improves the surface topography of fluorine doped SnO2 (FTO) substrate and perovskite (CH3NH3PbI3) layer. Thus, this SnO2 hole blocking layer can efficiently promote electron transport and suppress carrier recombination. Furthermore, the best efficiency of 13.68% was obtained for planar PSC with SnO2 hole blocking layer prepared at room temperature. This research highlights the room-temperature preparation process of hole blocking layer in PSC and has a certain reference significance for the usage of flexible and low-cost substrates.

Room-temperature electron spin relaxation of nitroxides immobilized in trehalose: Effect of substituents adjacent to NO-group

NASA Astrophysics Data System (ADS)

Kuzhelev, Andrey A.; Strizhakov, Rodion K.; Krumkacheva, Olesya A.; Polienko, Yuliya F.; Morozov, Denis A.; Shevelev, Georgiy Yu.; Pyshnyi, Dmitrii V.; Kirilyuk, Igor A.; Fedin, Matvey V.; Bagryanskaya, Elena G.

2016-05-01

Trehalose has been recently promoted as efficient immobilizer of biomolecules for room-temperature EPR studies, including distance measurements between attached nitroxide spin labels. Generally, the structure of nitroxide influences the electron spin relaxation times, being crucial parameters for room-temperature pulse EPR measurements. Therefore, in this work we investigated a series of nitroxides with different substituents adjacent to NO-moiety including spirocyclohexane, spirocyclopentane, tetraethyl and tetramethyl groups. Electron spin relaxation times (T1, Tm) of these radicals immobilized in trehalose were measured at room temperature at X- and Q-bands (9/34 GHz). In addition, a comparison was made with the corresponding relaxation times in nitroxide-labeled DNA immobilized in trehalose. In all cases phase memory times Tm were close to 700 ns and did not essentially depend on structure of substituents. Comparison of temperature dependences of Tm at T = 80-300 K shows that the benefit of spirocyclohexane substituents well-known at medium temperatures (∼100-180 K) becomes negligible at 300 K. Therefore, unless there are specific interactions between spin labels and biomolecules, the room-temperature value of Tm in trehalose is weakly dependent on the structure of substituents adjacent to NO-moiety of nitroxide. The issues of specific interactions and stability of nitroxide labels in biological media might be more important for room temperature pulsed dipolar EPR than differences in intrinsic spin relaxation of radicals.

Room temperature ferrimagnetism and ferroelectricity in strained, thin films of BiFe 0.5Mn 0.5O 3

DOE PAGES

Choi, Eun -Mi; Fix, Thomas; Kursumovic, Ahmed; ...

2014-10-14

In this study, highly strained films of BiFe 0.5Mn 0.5O 3 (BFMO) grown at very low rates by pulsed laser deposition were demonstrated to exhibit both ferrimagnetism and ferroelectricity at room temperature and above. Magnetization measurements demonstrated ferrimagnetism (T C ~ 600K), with a room temperature saturation moment (M S) of up to 90 emu/cc (~0.58μ B/f.u) on high quality (001) SrTiO 3. X-ray magnetic circular dichroism showed that the ferrimagnetism arose from antiferromagnetically coupled Fe 3+ and Mn 3+ . While scanning transmission electron microscope studies showed there was no long range ordering of Fe and Mn, the magneticmore » properties were found to be strongly dependent on the strain state in the films. The magnetism is explained to arise from one of three possible mechanisms with Bi polarization playing a key role. A signature of room temperature ferroelectricity in the films was measured by piezoresponse force microscopy and was confirmed using angular dark field scanning transmission electron microscopy. The demonstration of strain induced, high temperature multiferroism is a promising development for future spintronic and memory applications at room temperature and above.« less

High pressure phase transitions in lawsonite at simultaneous high pressure and temperature: A single crystal study

NASA Astrophysics Data System (ADS)

O'Bannon, E. F., III; Vennari, C.; Beavers, C. C. G.; Williams, Q. C.

2015-12-01

Lawsonite (CaAl2Si2O7(OH)2.H2O) is a hydrous mineral with a high overall water content of ~11.5 wt.%. It is a significant carrier of water in subduction zones to depths greater than ~150 km. The structure of lawsonite has been extensively studied under room temperature, high-pressure conditions. However, simultaneous high-pressure and high-temperature experiments are scarce. We have conducted synchrotron-based simultaneous high-pressure and temperature single crystal experiments on lawsonite up to a maximum pressure of 8.4 GPa at ambient and high temperatures. We used a natural sample of lawsonite from Valley Ford, California (Sonoma County). At room pressure and temperature lawsonite crystallizes in the orthorhombic system with Cmcm symmetry. Room temperature compression indicates that lawsonite remains in the orthorhombic Cmcm space group up to ~9.0 GPa. Our 5.0 GPa crystal structure is similar to the room pressure structure, and shows almost isotropic compression of the crystallographic axes. Unit cell parameters at 5.0 GPa are a- 5.7835(10), b- 8.694(2), and c- 13.009(3). Single-crystal measurements at simultaneous high-pressure and temperature (e.g., >8.0 GPa and ~100 oC) can be indexed to a monoclinic P-centered unit cell. Interestingly, a modest temperature increase of ~100 oC appears to initiate the orthorhombic to monoclinic phase transition at ~0.6-2.4 GPa lower than room temperature compression studies have shown. There is no evidence of dehydration or H atom disorder under these conditions. This suggests that the orthorhombic to monoclinic transition could be kinetically impeded at 298 K, and that monoclinic lawsonite could be the dominant water carrier through much of the depth range of upper mantle subduction processes.

Recrystallization in Si upon ion irradiation at room temperature in Co/Si(111) thin film systems

NASA Astrophysics Data System (ADS)

Banu, Nasrin; Satpati, B.; Dev, B. N.

2018-04-01

After several decades of research it was concluded that for a constant flux recrystallization in Si upon ion irradiation is possible only at high temperature. At low temperature or at room temperature only amorphization can take place. However we have observed recrystallization in Si upon ion irradiation at room temperature in a Co/Si thin film system. The Co/Si sample was prepared by deposition of 25 nm Co on clean Si(111) substrate. An oxide layer (˜ 2nm) of cobalt at the top of the film due to air exposure. The ion irradiation was done at room temperature under high vacuum with 1MeV Si+ ion with low beam current < 400 nA. Earlier we have shown similar ion induced recrystallization in Si(100) substrate which had a sandwich Si/Ni/Si structure. This system had an epitaxial buffer Si layer on Si substrate. This study also shows that the phenomenon is independent of substrate orientation and buffer layer. We have used transmission electron microscopy (TEM) to study the recrystallization behavior.

Thermal responses from repeated exposures to severe cold with intermittent warmer temperatures.

PubMed

Ozaki, H; Enomoto-Koshimizu, H; Tochihara, Y; Nakamura, K

1998-09-01

This study was conducted to evaluate physiological reaction and manual performance during exposure to warm (30 degrees C) and cool (10 degrees C) environments after exposure to very low temperatures (-25 degrees C). Furthermore, this experiment was conducted to study whether it is desirable to remove cold-protective jackets in warmer rooms after severe cold exposure. Eight male students remained in an extremely cold room for 20 min, after which they transferred into either the warm room or the cool room for 20 min. This pattern was repeated three times, and the total cold exposure time was 60 min. In the warm and cool rooms, the subjects either removed their cold-protective jackets (Condition A), or wore them continuously (Condition B). Rectal temperature, skin temperatures, manual performance, blood pressure, thermal, comfort and pain sensations were measured during the experiment. The effects of severe cold on almost all measurements in the cool (10 degrees C) environment were greater than those in the warm (30 degrees C) environment under both clothing conditions. The effects of severe cold on all measurements under Condition A except rectal temperature and toe skin temperature were significantly greater than those under Condition B in the cool environment but, not at all differences between Condition A and Condition B in the warm environments were significant. It was recognized that to remove cold-protective jackets in the cool room (10 degrees C) after severe cold exposure promoted the effects of severe cold. When rewarming in the warm resting room (30 degrees C), the physiological and psychological responses and manual performance were not influenced by the presence or absence of cold-protective clothing. These results suggest that it is necessary for workers to make sure to rewarm in the warm room outside of the cold storage and continue to wear cold-protective clothing in the cool room.

Room temperature growth of ZnO nanorods by hydrothermal synthesis

NASA Astrophysics Data System (ADS)

Tateyama, Hiroki; Zhang, Qiyan; Ichikawa, Yo

2018-05-01

The effect of seed layer morphology on ZnO nanorod growth at room temperature was studied via hydrothermal synthesis on seed layers with different thicknesses and further annealed at different temperatures. The change in the thickness and annealing temperature enabled us to control over a diameter of ZnO nanorods which are attributed to the changing of crystallinity and roughness of the seed layers.

Spoof plasmon waveguide enabled ultrathin room temperature THz GaN quantum cascade laser: a feasibility study.

PubMed

Sun, Greg; Khurgin, Jacob B; Tsai, Din Ping

2013-11-18

We propose and study the feasibility of a THz GaN/AlGaN quantum cascade laser (QCL) consisting of only five periods with confinement provided by a spoof surface plasmon (SSP) waveguide for room temperature operation. The QCL design takes advantages of the large optical phonon energy and the ultrafast phonon scattering in GaN that allow for engineering favorable laser state lifetimes. Our analysis has shown that the waveguide loss is sufficiently low for the QCL to reach its threshold at the injection current density around 6 kA/cm2 at room temperature.

Charge carrier dynamics of GaAs/AlGaAs asymmetric double quantum wells at room temperature studied by optical pump terahertz probe spectroscopy

NASA Astrophysics Data System (ADS)

Afalla, Jessica; Ohta, Kaoru; Tokonami, Shunrou; Prieto, Elizabeth Ann; Catindig, Gerald Angelo; Cedric Gonzales, Karl; Jaculbia, Rafael; Vasquez, John Daniel; Somintac, Armando; Salvador, Arnel; Estacio, Elmer; Tani, Masahiko; Tominaga, Keisuke

2017-11-01

Two asymmetric double quantum wells of different coupling strengths (barrier widths) were grown via molecular beam epitaxy, both samples allowing tunneling. Photoluminescence was measured at 10 and 300 K to provide evidence of tunneling, barrier dependence, and structural uniformity. Carrier dynamics at room temperature was investigated by optical pump terahertz probe (OPTP) spectroscopy. Carrier population decay rates were obtained and photoconductivity spectra were analyzed using the Drude model. This work demonstrates that carrier, and possibly tunneling dynamics in asymmetric double quantum well structures may be studied at room temperature through OPTP spectroscopy.

Effect of a common diet and regular beverage on enamel erosion in various temperatures: an in-vitro study.

PubMed

Khamverdi, Zahra; Vahedi, Mohammad; Abdollahzadeh, Shermin; Ghambari, Mohammad Hosein

2013-09-01

This study compared diet and regular Coca-Cola on enamel erosion in cold and room temperatures. Seventy five enamel specimens were prepared and divided into 5 equal groups (N=15) as follows: Group 1: regular beverage at room temperature, Group 2: regular beverage at refri-gerator temperature, Group 3: diet beverage at room and Group 4: diet beverage at refrige-rator temperature. The specimens were immersed in the regular or diet beverage (Coca-Cola, trade mark regd. Khoshgovar Co., Tehran, Iran) at room (20°C) or refrigerator (2°C) temperatures for 20 minutes, 3 times per day for 7 days. Specimens in the control subjects (group 5) were placed in synthetic saliva at room temperature for 7 days. The hardness of specimens was tested using Vickers test under 500 gr loads for 5 seconds. The data were analyzed using two-way ANOVA and Tukey tests. The mean and standard deviations of micro-hardness values of the studied groups were as follow: G1: 304.26±29.71, G2: 285.53±42.14, G3: 279.06±39.52, G4: 266.80±23.98 and G5: 319± 30.79. There was a significant difference in the beverage type as the main factor (p<0.05), but temperature factor and their interaction effect on enamel hardness showed no significant difference (p>0.05). Tukey tests showed that there were significant differences between control and diet groups as well as regular and diet groups. Diet Coca-Cola is more erosive than the regular type and the temperature of the beverages used had no significant influence on enamel erosion.

Effect of a Common Diet and Regular Beverage on Enamel Erosion in Various Temperatures: An In-Vitro Study

PubMed Central

Khamverdi, Zahra; Vahedi, Mohammad; Abdollahzadeh, Shermin; Ghambari, Mohammad Hosein

2013-01-01

Objective: This study compared diet and regular Coca-Cola on enamel erosion in cold and room temperatures. Materials and Methods: Seventy five enamel specimens were prepared and divided into 5 equal groups (N=15) as follows: Group 1: regular beverage at room temperature, Group 2: regular beverage at refri-gerator temperature, Group 3: diet beverage at room and Group 4: diet beverage at refrige-rator temperature. The specimens were immersed in the regular or diet beverage (Coca-Cola, trade mark regd. Khoshgovar Co., Tehran, Iran) at room (20°C) or refrigerator (2°C) temperatures for 20 minutes, 3 times per day for 7 days. Specimens in the control subjects (group 5) were placed in synthetic saliva at room temperature for 7 days. The hardness of specimens was tested using Vickers test under 500 gr loads for 5 seconds. The data were analyzed using two-way ANOVA and Tukey tests. Results: The mean and standard deviations of micro-hardness values of the studied groups were as follow: G1: 304.26±29.71, G2: 285.53±42.14, G3: 279.06±39.52, G4: 266.80±23.98 and G5: 319± 30.79. There was a significant difference in the beverage type as the main factor (p<0.05), but temperature factor and their interaction effect on enamel hardness showed no significant difference (p>0.05). Tukey tests showed that there were significant differences between control and diet groups as well as regular and diet groups. Conclusion: Diet Coca-Cola is more erosive than the regular type and the temperature of the beverages used had no significant influence on enamel erosion. PMID:24910648

Effect of 120 MeV Ag9+ ion irradiation of YCOB single crystals

NASA Astrophysics Data System (ADS)

Arun Kumar, R.; Dhanasekaran, R.

2012-09-01

Single crystals of yttrium calcium oxy borate (YCOB) grown from boron-tri-oxide flux were subjected to swift heavy ion irradiation using silver Ag9+ ions from the 15 UD Pelletron facility at Inter University Accelerator Center, New Delhi. The crystals were irradiated at 1 × 1013, 5 × 1013 and 1 × 1014 ions/cm2 fluences at room temperature and with 5 × 1013 ions/cm2 fluence at liquid nitrogen temperature. The pristine and the irradiated samples were characterized by glancing angle X-ray diffraction, UV-Vis-NIR and photoluminescence studies. From the characterization studies performed on the samples, it is inferred that the crystals irradiated at liquid nitrogen temperature had fewer defects compared to the crystals irradiated at room temperature and the defects increased when the ion fluence was increased at room temperature.

Correcting for Microbial Blooms in Fecal Samples during Room-Temperature Shipping.

PubMed

Amir, Amnon; McDonald, Daniel; Navas-Molina, Jose A; Debelius, Justine; Morton, James T; Hyde, Embriette; Robbins-Pianka, Adam; Knight, Rob

2017-01-01

The use of sterile swabs is a convenient and common way to collect microbiome samples, and many studies have shown that the effects of room-temperature storage are smaller than physiologically relevant differences between subjects. However, several bacterial taxa, notably members of the class Gammaproteobacteria , grow at room temperature, sometimes confusing microbiome results, particularly when stability is assumed. Although comparative benchmarking has shown that several preservation methods, including the use of 95% ethanol, fecal occult blood test (FOBT) and FTA cards, and Omnigene-GUT kits, reduce changes in taxon abundance during room-temperature storage, these techniques all have drawbacks and cannot be applied retrospectively to samples that have already been collected. Here we performed a meta-analysis using several different microbiome sample storage condition studies, showing consistent trends in which specific bacteria grew (i.e., "bloomed") at room temperature, and introduce a procedure for removing the sequences that most distort analyses. In contrast to similarity-based clustering using operational taxonomic units (OTUs), we use a new technique called "Deblur" to identify the exact sequences corresponding to blooming taxa, greatly reducing false positives and also dramatically decreasing runtime. We show that applying this technique to samples collected for the American Gut Project (AGP), for which participants simply mail samples back without the use of ice packs or other preservatives, yields results consistent with published microbiome studies performed with frozen or otherwise preserved samples. IMPORTANCE In many microbiome studies, the necessity to store samples at room temperature (i.e., remote fieldwork) and the ability to ship samples without hazardous materials that require special handling training, such as ethanol (i.e., citizen science efforts), is paramount. However, although room-temperature storage for a few days has been shown not to obscure physiologically relevant microbiome differences between comparison groups, there are still changes in specific bacterial taxa, notably, in members of the class Gammaproteobacteria , that can make microbiome profiles difficult to interpret. Here we identify the most problematic taxa and show that removing sequences from just a few fast-growing taxa is sufficient to correct microbiome profiles.

Correcting for Microbial Blooms in Fecal Samples during Room-Temperature Shipping

PubMed Central

Amir, Amnon; McDonald, Daniel; Navas-Molina, Jose A.; Debelius, Justine; Morton, James T.; Hyde, Embriette; Robbins-Pianka, Adam

2017-01-01

ABSTRACT The use of sterile swabs is a convenient and common way to collect microbiome samples, and many studies have shown that the effects of room-temperature storage are smaller than physiologically relevant differences between subjects. However, several bacterial taxa, notably members of the class Gammaproteobacteria, grow at room temperature, sometimes confusing microbiome results, particularly when stability is assumed. Although comparative benchmarking has shown that several preservation methods, including the use of 95% ethanol, fecal occult blood test (FOBT) and FTA cards, and Omnigene-GUT kits, reduce changes in taxon abundance during room-temperature storage, these techniques all have drawbacks and cannot be applied retrospectively to samples that have already been collected. Here we performed a meta-analysis using several different microbiome sample storage condition studies, showing consistent trends in which specific bacteria grew (i.e., “bloomed”) at room temperature, and introduce a procedure for removing the sequences that most distort analyses. In contrast to similarity-based clustering using operational taxonomic units (OTUs), we use a new technique called “Deblur” to identify the exact sequences corresponding to blooming taxa, greatly reducing false positives and also dramatically decreasing runtime. We show that applying this technique to samples collected for the American Gut Project (AGP), for which participants simply mail samples back without the use of ice packs or other preservatives, yields results consistent with published microbiome studies performed with frozen or otherwise preserved samples. IMPORTANCE In many microbiome studies, the necessity to store samples at room temperature (i.e., remote fieldwork) and the ability to ship samples without hazardous materials that require special handling training, such as ethanol (i.e., citizen science efforts), is paramount. However, although room-temperature storage for a few days has been shown not to obscure physiologically relevant microbiome differences between comparison groups, there are still changes in specific bacterial taxa, notably, in members of the class Gammaproteobacteria, that can make microbiome profiles difficult to interpret. Here we identify the most problematic taxa and show that removing sequences from just a few fast-growing taxa is sufficient to correct microbiome profiles. PMID:28289733

Preparation of Boron Nitride Nanoparticles with Oxygen Doping and a Study of Their Room-Temperature Ferromagnetism.

PubMed

Lu, Qing; Zhao, Qi; Yang, Tianye; Zhai, Chengbo; Wang, Dongxue; Zhang, Mingzhe

2018-04-18

In this work, oxygen-doped boron nitride nanoparticles with room-temperature ferromagnetism have been synthesized by a new, facile, and efficient method. There are no metal magnetic impurities in the nanoparticles analyzed by X-ray photoelectron spectroscopy. The boron nitride nanoparticles exhibit a parabolic shape with increase in the reaction time. The saturation magnetization value reaches a maximum of 0.2975 emu g -1 at 300 K when the reaction time is 12 h, indicating that the Curie temperature ( T C ) is higher than 300 K. Combined with first-principles calculation, the coupling between B 2p orbital, N 2p orbital, and O 2p orbital in the conduction bands is the main origin of room-temperature ferromagnetism and also proves that the magnetic moment changes according the oxygen-doping content change. Compared with other room temperature ferromagnetic semiconductors, boron nitride nanoparticles have widely potential applications in spintronic devices because of high temperature oxidation resistance and excellent chemical stability.

Toward hydrogen detection at room temperature with printed ZnO nanoceramics films activated with halogen lighting

NASA Astrophysics Data System (ADS)

Nguyen, Van Son; Jubera, Véronique; Garcia, Alain; Debéda, Hélène

2015-12-01

Though semiconducting properties of ZnO have been extensively investigated under hazardous gases, research is still necessary for low-cost sensors working at room temperature. Study of printed ZnO nanopowders-based sensors has been undertaken for hydrogen detection. A ZnO paste made with commercial nanopowders is deposited onto interdigitated Pt electrodes and sintered at 400 °C. The ZnO layer structure and morphology are first examined by XRD, SEM, AFM and emission/excitation spectra prior to the study of the effect of UV-light on the electrical conduction of the semiconductor oxide. The response to hydrogen exposure is subsequently examined, showing that low UV-light provided by halogen lighting enhances the gas response and allows detection at room temperature with gas responses similar to those obtained in dark conditions at 150 °C. A gas response of 44% (relative change in current) under 300 ppm is obtained at room temperature. Moreover, it is demonstrated that very low UV-light power (15 μW/mm2) provided by the halogen lamp is sufficient to give sensitivities as high as those for much higher powers obtained with a UV LED (7.7 mW/mm2). These results are comparable to those obtained by others for 1D or 2D ZnO nanostructures working at room temperature or at temperatures up to 250 °C.

Highly selective room temperature NO2 gas sensor based on rGO-ZnO composite

NASA Astrophysics Data System (ADS)

Jyoti, Kanaujiya, Neha; Varma, G. D.

2018-05-01

Blending metal oxide nanoparticles with graphene or its derivatives can greatly enhance gas sensing characteristics. In the present work, ZnO nanoparticles have been synthesized via reflux method. Thin films of reduced graphene oxide (rGO) and composite of rGO-ZnO have been fabricated by drop casting method for gas sensing application. The samples have been characterized by X-ray diffraction (XRD) and Field-emission scanning electron microscope (FESEM) for the structural and morphological studies respectively. Sensing measurements have been carried out for the composite film of rGO-ZnO for different concentrations of NO2 ranging from 4 to 100 ppm. Effect of increasing temperature on the sensing performance has also been studied and the rGO-ZnO composite sensor shows maximum percentage response at room temperature. The limit of detection (LOD) for rGO-ZnO composite sensor is 4ppm and it exhibits a high response of 48.4% for 40 ppm NO2 at room temperature. To check the selectivity of the composite sensor, sensor film has been exposed to 40 ppm different gases like CO, NH3, H2S and Cl2 at room temperature and the sensor respond negligibly to these gases. The present work suggests that rGO-ZnO composite material can be a better candidate for fabrication of highly selective room temperature NO2 gas sensor.

Real-time modeling of heat distributions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hamann, Hendrik F.; Li, Hongfei; Yarlanki, Srinivas

Techniques for real-time modeling temperature distributions based on streaming sensor data are provided. In one aspect, a method for creating a three-dimensional temperature distribution model for a room having a floor and a ceiling is provided. The method includes the following steps. A ceiling temperature distribution in the room is determined. A floor temperature distribution in the room is determined. An interpolation between the ceiling temperature distribution and the floor temperature distribution is used to obtain the three-dimensional temperature distribution model for the room.

The influence of room temperature on Mg isotope measurements by MC-ICP-MS.

PubMed

Zhang, Xing-Chao; Zhang, An-Yu; Zhang, Zhao-Feng; Huang, Fang; Yu, Hui-Min

2018-03-24

We observed that the accuracy and precision of magnesium (Mg) isotope analyses could be affected if the room temperature oscillated during measurements. To achieve high quality Mg isotopic data, it is critical to evaluate how the unstable room temperature affects Mg isotope measurements by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). We measured the Mg isotopes for the reference material DSM-3 using MC-ICP-MS under oscillating room temperatures in spring. For a comparison, we also measured the Mg isotopes under stable room temperatures, which was achieved by the installation of an improved temperature control system in the laboratory. The δ 26 Mg values measured under oscillating room temperatures have a larger deviation (δ 26 Mg from -0.09 to 0.08‰, with average δ 26 Mg = 0.00 ± 0.08 ‰) than those measured under a stable room temperature (δ 26 Mg from -0.03 to 0.03‰, with average δ 26 Mg = 0.00 ± 0.02 ‰) using the same MC-ICP-MS system. The room temperature variation can influence the stability of MC-ICP-MS. Therefore, it is critical to keep the room temperature stable to acquire high precise and accurate isotopic data when using MC-ICP-MS, especially when using the sample-standard bracketing (SSB) correction method. This article is protected by copyright. All rights reserved.

Comparison of the bioavailability and adhesiveness of different rotigotine transdermal patch formulations.

PubMed

Elshoff, Jan-Peer; Timmermann, Lars; Schmid, Miriam; Arth, Christoph; Komenda, Michael; Brunnert, Marcus; Bauer, Lars

2013-12-01

Rotigotine transdermal patch is approved for the treatment of early and advanced idiopathic Parkinson's disease (PD) and moderate-to-severe idiopathic restless legs syndrome (RLS). A cold chain manufacturing and distribution process was temporarily implemented in 2008, as this reduced the crystal formation reported within patches stored at room temperature. In order to overcome the crystallization issue and meet EMA and FDA requirements, a new room temperature stable formulation was developed. The three studies reported here were conducted to determine whether the new room temperature stable patch demonstrated similar bioavailability and adhesiveness to the original and intermediate patches. Data are reported from three cross-over studies that compared the original, cold chain and room temperature stable patch. Two open-label bioequivalence studies investigated the 2 mg/24 h dosage in healthy individuals (SP951, n = 52 [Clinicaltrials.gov: NCT00881894]; SP0987, n = 50 [NCT01059903]) and a double-blind patch adhesiveness study investigated the 8 mg/24 h dosage in patients with PD (SP1066, n = 56 [NCT01338896]). Plasma concentration-time curves and geometric means for pharmacokinetic parameters were similar for the cold chain vs. original patch in SP951 (AUC(0-tz): 2.68 vs. 2.71 ng/mL*h; point estimate: 0.99 [90% confidence interval (CI): 0.91, 1.07]) (Cmax: 0.131 vs. 0.136 ng/mL; 0.96 [0.89, 1.04]) and for the room temperature stable vs. cold chain patch in SP0987 (AUC(0-tz): 4.51 vs. 4.87 ng/mL*h; 0.90 [0.84, 0.97]) (Cmax: 0.23 vs. 0.23 ng/mL; 0.95 [0.88, 1.02]). In both studies, 90% CIs for ratios of AUC(0-tz) and Cmax were within the bioequivalence acceptance range (0.8-1.25). In SP1066, overall median adhesiveness scores were similar for cold chain (0.5 [range: 0-4]) and room temperature stable (0 [0-4]) formulations. These results demonstrated bioequivalence and indicated similar adhesiveness of the approved room temperature stable rotigotine patch with the original and cold chain patches. Potential limitations include the enrolment of healthy volunteers in the bioequivalence studies, as these individuals were likely to be younger than the general PD or RLS population.

Pyroelectric effect and lattice thermal conductivity of InN/GaN heterostructures

NASA Astrophysics Data System (ADS)

Hansdah, Gopal; Sahoo, Bijay Kumar

2018-06-01

The built-in-polarization (BIP) of InN/GaN heterostructures enhances Debye temperature, phonon mean free path and thermal conductivity of the heterostructure at room temperature. The variation of thermal conductivities (kp: including polarization mechanism and k: without polarization mechanism) with temperature predicts the existence of a transition temperature (Tp) between primary and secondary pyroelectric effect. Below Tp, kp is lower than k; while above Tp, kp is significantly contributed from BIP mechanism due to thermal expansion. A thermodynamic theory has been proposed to explain the result. The room temperature thermal conductivity of InN/GaN heterostructure with and without polarization is respectively 32 and 48 W m-1 K-1. The temperature Tp and room temperature pyroelectric coefficient of InN has been predicted as 120 K and -8.425 μC m-2 K-1, respectively which are in line with prior literature studies. This study suggests that thermal conductivity measurement in InN/GaN heterostructures can help to understand the role of phonons in pyroelectricity.

Resonant Ultrasound Spectroscopy studies of Berea sandstone at high temperature

DOE PAGES

Davis, Eric S.; Sturtevant, Blake T.; Sinha, Dipen N.; ...

2016-09-04

Resonant Ultrasound Spectroscopy was used in this paper to determine the elastic moduli of Berea sandstone from room temperature to 478 K. Sandstone is a common component of oil reservoirs, and the temperature range was chosen to be representative of typical downhole conditions, down to about 8 km. In agreement with previous works, Berea sandstone was found to be relatively soft with a bulk modulus of approximately 6 GPa as compared to 37.5 GPa for α-quartz at room temperature and pressure. Finally, it was found that Berea sandstone undergoes a ~17% softening in bulk modulus between room temperature and 385more » K, followed by an abnormal behavior of similar stiffening between 385 K and 478 K.« less

Resonant Ultrasound Spectroscopy studies of Berea sandstone at high temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, Eric S.; Sturtevant, Blake T.; Sinha, Dipen N.

Resonant Ultrasound Spectroscopy was used in this paper to determine the elastic moduli of Berea sandstone from room temperature to 478 K. Sandstone is a common component of oil reservoirs, and the temperature range was chosen to be representative of typical downhole conditions, down to about 8 km. In agreement with previous works, Berea sandstone was found to be relatively soft with a bulk modulus of approximately 6 GPa as compared to 37.5 GPa for α-quartz at room temperature and pressure. Finally, it was found that Berea sandstone undergoes a ~17% softening in bulk modulus between room temperature and 385more » K, followed by an abnormal behavior of similar stiffening between 385 K and 478 K.« less

Room-temperature serial crystallography at synchrotron X-ray sources using slowly flowing free-standing high-viscosity microstreams.

PubMed

Botha, Sabine; Nass, Karol; Barends, Thomas R M; Kabsch, Wolfgang; Latz, Beatrice; Dworkowski, Florian; Foucar, Lutz; Panepucci, Ezequiel; Wang, Meitian; Shoeman, Robert L; Schlichting, Ilme; Doak, R Bruce

2015-02-01

Recent advances in synchrotron sources, beamline optics and detectors are driving a renaissance in room-temperature data collection. The underlying impetus is the recognition that conformational differences are observed in functionally important regions of structures determined using crystals kept at ambient as opposed to cryogenic temperature during data collection. In addition, room-temperature measurements enable time-resolved studies and eliminate the need to find suitable cryoprotectants. Since radiation damage limits the high-resolution data that can be obtained from a single crystal, especially at room temperature, data are typically collected in a serial fashion using a number of crystals to spread the total dose over the entire ensemble. Several approaches have been developed over the years to efficiently exchange crystals for room-temperature data collection. These include in situ collection in trays, chips and capillary mounts. Here, the use of a slowly flowing microscopic stream for crystal delivery is demonstrated, resulting in extremely high-throughput delivery of crystals into the X-ray beam. This free-stream technology, which was originally developed for serial femtosecond crystallography at X-ray free-electron lasers, is here adapted to serial crystallography at synchrotrons. By embedding the crystals in a high-viscosity carrier stream, high-resolution room-temperature studies can be conducted at atmospheric pressure using the unattenuated X-ray beam, thus permitting the analysis of small or weakly scattering crystals. The high-viscosity extrusion injector is described, as is its use to collect high-resolution serial data from native and heavy-atom-derivatized lysozyme crystals at the Swiss Light Source using less than half a milligram of protein crystals. The room-temperature serial data allow de novo structure determination. The crystal size used in this proof-of-principle experiment was dictated by the available flux density. However, upcoming developments in beamline optics, detectors and synchrotron sources will enable the use of true microcrystals. This high-throughput, high-dose-rate methodology provides a new route to investigating the structure and dynamics of macromolecules at ambient temperature.

The effect of ultraviolet irradiation on the ultra-thin HfO{sub 2} based CO gas sensor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karaduman, Irmak; Barin, Özlem; Acar, Selim

2015-11-07

In this work, an effort has been made to fabricate ultrathin HfO{sub 2}/Al{sub 2}O{sub 3} sample by atomic layer deposition method for the fast detection of CO gas at room temperature. The effect of the operating temperature and the UV light on the gas sensing characteristics has been studied. We investigated the optimum operating temperature for the sample by sensing 25 ppm CO and CO{sub 2} gases from room temperature to 150 °C for 10 °C steps. The maximum response was obtained at 150 °C for both gases in the measurement temperature range. Also, the photoresponse measurements clearly show the effect of UV lightmore » on the sample. At room temperature, sensor showed superior response (14%) for 5 ppm CO gas. The response time of sensor is 6 s to 5 ppm CO gas concentration. The ultrathin HfO{sub 2} based sample shows acceptable gas sensitivity for 5 ppm CO gas at room temperature under UV light irradiation.« less

Superparamagnetic nanocrystalline ZnFe2O4 with a very high Curie temperature.

PubMed

Deka, Sasanka; Joy, P A

2008-08-01

Studies on the magnetic properties of nanocrystalline ZnFe2O4 synthesized by an autocombustion method are reported. Superparamagnetic behavior is observed for the nanocrystalline materials with particle sizes of 8 nm and 17 nm, with superparamagnetic blocking temperatures of 65 K and 75 K, respectively. Magnetic hysteresis with very large coercivities of 533 Oe and 325 Oe, respectively, are observed at 12 K. Studies on the temperature variation of the magnetization above room temperature indicate that the Curie temperature is as high as approximately 800 K when compared to the paramagnetic nature of bulk zinc ferrite at room temperature.

Feasibility study for the development of low temperature curing adhesives

NASA Technical Reports Server (NTRS)

Green, H. E.; Sutherland, J. D.; Sheppard, C. H.

1974-01-01

The feasibility of a new approach for the development of stable, easily handled, room temperature (293 K - 311 K) curing adhesives was studied and demonstrated. The work concentrated on a family of unsaturated amide/ester resins. Twelve candidate resins were synthesized and tested for completeness of cure at room temperature, adhesion to aluminum and titanium, shear strength, moisture resistance and heat stability. The three most promising candidate resins were selected and recommended for further development.

Long-term hot-hardness characteristics of five through-hardened bearing steels

NASA Technical Reports Server (NTRS)

Anderson, N. E.

1978-01-01

Five vacuum-melted bearing steels tempered to various room temperature hardnesses: AISI 52100 and the tool steels AISI M-1, AISI M-50, Halmo, and WB-49 were studied. Hardness measurements were taken on AISI 52100 at room temperature and at elevated temperatures after soaking it at temperatures to 478 K (400 F) for as long as 1000 hours. Hardness measurements were also taken on the tool steels after soaking them at temperatures to 700 K (800 F) for as long at 1000 hours. None of the tool steel tempered during soaking and AISI 52100 did not temper when soaked at 366 K (200 F) for 1000 hours. However, AISI 52100 that was initially hardened to room temperature hardness of 62.5 or 64.5 lost hardness during the first 500 hours of the 1000-hour soak tests at temperatures greater than 394 K (250 F), but it maintained its hardness during the final 500 hours of soaking. Similarly, AISI 52100 initially hardened to room temperature hardness of 60.5 lost hardness during the first 500 hours of the 1000-hour soaking at temperatures greater than 422 K (300 F), but it maintained its hardness during the final 500 hours of soaking.

State-resolved Thermal/Hyperthermal Dynamics of Atmospheric Species

DTIC Science & Technology

2015-06-23

gas -room temperature ionic liquid (RTIL) interfaces. 2) Large scale trajectory simulations for theoretical analysis of gas - liquid scattering studies...areas: 1) Diode laser and LIF studies of hyperthermal CO2 and NO collisions at the gas -room temperature ionic liquid (RTIL) interfaces. 2) Large...scale trajectory simulations for theoretical analysis of gas - liquid scattering studies, 3) LIF data for state-resolved scattering of hyperthermal NO at

Quantum confinement of zero-dimensional hybrid organic-inorganic polaritons at room temperature

NASA Astrophysics Data System (ADS)

Nguyen, H. S.; Han, Z.; Abdel-Baki, K.; Lafosse, X.; Amo, A.; Lauret, J.-S.; Deleporte, E.; Bouchoule, S.; Bloch, J.

2014-02-01

We report on the quantum confinement of zero-dimensional polaritons in perovskite-based microcavity at room temperature. Photoluminescence of discrete polaritonic states is observed for polaritons localized in symmetric sphere-like defects which are spontaneously nucleated on the top dielectric Bragg mirror. The linewidth of these confined states is found much sharper (almost one order of magnitude) than that of photonic modes in the perovskite planar microcavity. Our results show the possibility to study organic-inorganic cavity polaritons in confined microstructure and suggest a fabrication method to realize integrated polaritonic devices operating at room temperature.

Comparison of room temperature and cyrogenic sample processing in the analysis of chemical contaminants in foods

USDA-ARS?s Scientific Manuscript database

In this study, analytical results were compared when using different approaches to bulk food sample comminution, consisting of a vertical chopper (Blixer) at room temperature and at dry ice cryogenic conditions, followed by further subsample processing (20 g) using liquid nitrogen cryogenic conditio...

Room temperature single-photon detectors for high bit rate quantum key distribution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Comandar, L. C.; Patel, K. A.; Engineering Department, Cambridge University, 9 J J Thomson Ave., Cambridge CB3 0FA

We report room temperature operation of telecom wavelength single-photon detectors for high bit rate quantum key distribution (QKD). Room temperature operation is achieved using InGaAs avalanche photodiodes integrated with electronics based on the self-differencing technique that increases avalanche discrimination sensitivity. Despite using room temperature detectors, we demonstrate QKD with record secure bit rates over a range of fiber lengths (e.g., 1.26 Mbit/s over 50 km). Furthermore, our results indicate that operating the detectors at room temperature increases the secure bit rate for short distances.

Seasonal mapping of NICU temperature.

PubMed

Thomas, Karen A; Magbalot, Almita; Shinabarger, Kelley; Mokhnach, Larisa; Anderson, Marilyn; Diercks, Kristi; Millar, April; Thorngate, Lauren; Walker, Wendy; Dilback, Nancy; Berkan, Maureen

2010-04-01

To create a thermal map of ambient air, radiant, and evaporative temperatures and humidity throughout the NICU nursery by season across a calendar year. Each cubicle of the 32-bed NICU, distributed across 5 rooms, in a level III nursery was measured. Temperatures were recorded at a consistent time on one day during January, April, July, and October. An electronic monitor (QUESTemp degrees 34; Quest Technologies, Oconomowoc, Wisconsin) was used to measure dry bulb, wet bulb, and globe thermometer temperatures. Analysis of variance revealed statistically significant (P < .000) differences in season, room, and season by room interaction. Room ambient air temperatures differed by less than 2 degrees F across season. Radiant temperature paralleled air temperature. Humidity, the predominant difference across season, produced evaporative temperatures considerably lower than room air temperature, and the gradient between mean nursery dry bulb temperature and wet bulb temperature was 9.3 degrees F in summer and 16.8 degrees F in winter. The thermal map revealed seasonal thermal differences, particularly in humidity level and evaporative temperature. Room temperature alone does not reflect the total thermal environment. Recommendations include periodic assessment of nurseries along with air, evaporative, and radiant temperatures as well as humidity to fully appreciate the impact of the thermal environment on infants.

Seasonal mapping of NICU temperature.

PubMed

Thomas, Karen A; Magbalot, Almita; Shinabarger, Kelley; Mokhnach, Larisa; Anderson, Marilyn; Diercks, Kristi; Millar, April; Thorngate, Lauren; Walker, Wendy; Dilback, Nancy; Berkan, Maureen

2010-10-01

To create a thermal map of ambient air, radiant, and evaporative temperatures and humidity throughout the NICU nursery by season across a calendar year. Each cubicle of the 32-bed NICU, distributed across 5 rooms, in a level III nursery was measured. Temperatures were recorded at a consistent time on one day during January, April, July, and October. : An electronic monitor (QUESTemp ° 34; Quest Technologies, Oconomowoc, Wisconsin) was used to measure dry bulb, wet bulb, and globe thermometer temperatures. Analysis of variance revealed statistically significant (P ≤ .000) differences in season, room, and season by room interaction. Room ambient air temperatures differed by less than 2 ° F across season. Radiant temperature paralleled air temperature. Humidity, the predominant difference across season, produced evaporative temperatures considerably lower than room air temperature, and the gradient between mean nursery dry bulb temperature and wet bulb temperature was 9.3 ° F in summer and 16.8 ° F in winter. The thermal map revealed seasonal thermal differences, particularly in humidity level and evaporative temperature. Room temperature alone does not reflect the total thermal environment. Recommendations include periodic assessment of nurseries along with air, evaporative, and radiant temperatures as well as humidity to fully appreciate the impact of the thermal environment on infants.

Quality of red blood cells isolated from umbilical cord blood stored at room temperature.

PubMed

Zhurova, Mariia; Akabutu, John; Acker, Jason

2012-01-01

Red blood cells (RBCs) from cord blood contain fetal hemoglobin that is predominant in newborns and, therefore, may be more appropriate for neonatal transfusions than currently transfused adult RBCs. Post-collection, cord blood can be stored at room temperature for several days before it is processed for stem cells isolation, with little known about how these conditions affect currently discarded RBCs. The present study examined the effect of the duration cord blood spent at room temperature and other cord blood characteristics on cord RBC quality. RBCs were tested immediately after their isolation from cord blood using a broad panel of quality assays. No significant decrease in cord RBC quality was observed during the first 65 hours of storage at room temperature. The ratio of cord blood to anticoagulant was associated with RBC quality and needs to be optimized in future. This knowledge will assist in future development of cord RBC transfusion product.

[Association between ambient temperature and hospital emergency room visits for cardiovascular diseases: a case-crossover study].

PubMed

Guo, Yu-Ming; Wang, Jia-Jia; Li, Guo-Xing; Zheng, Ya-An; He, Wichmann; Pan, Xiao-Chuan

2009-08-01

To explore the association between ambient average temperature and hospital emergency room visits for cardiovascular diseases (International Classification of Diseases, Tenth Vision ICD-10: I00 - I99) in Beijing, China. Data was collected on daily hospital emergency room visits for cardiovascular diseases from Peking University Third Hospital, including meteorological data (daily average temperature, relative humidity, wind speed, and atmospheric pressure) from the China Meteorological Data Sharing Service System, and on air pollution from the Beijing Municipal Environmental Monitoring Center. Time-stratified case-crossover design was used to analyze data on 4 seasons. After adjusting data on air pollution, 1 degree ( degrees C) increase of ambient average temperature would associate with the emergency room visits of odds ratio (ORs) as 1.282 (95%CI: 1.250 - 1.315), 1.027 (95%CI: 1.001 - 1.055), 0.661 (95%CI: 0.637 - 0.687), and 0.960 (95%CI: 0.937 - 0.984) in spring, summer, autumn, and winter respectively. After controlling the influence of relative humidity, wind speed, and atmospheric pressure, 1 degrees C increase in the ambient average temperature would be associated with the emergency room visits on ORs value as 1.423 (95%CI: 1.377 - 1.471), 1.082 (95%CI: 1.041 - 1.124), 0.633 (95%CI: 0.607 - 0.660) and 0.971 (95%CI: 0.944 - 1.000) in spring, summer, autumn, and winter respectively. These data on outcomes suggested that the elevated level of ambient temperature would increase the hospital emergency room visits for cardiovascular diseases in spring and summer while the elevated level of ambient temperature would decrease the hospital emergency room visits for the cardiovascular diseases in autumn and winter, suggesting that patients with cardiovascular diseases should pay attention to the climate change.

The effect of preheated versus room-temperature skin disinfection on bacterial colonization during pacemaker device implantation: a randomized controlled non-inferiority trial.

PubMed

Wistrand, Camilla; Söderquist, Bo; Magnusson, Anders; Nilsson, Ulrica

2015-01-01

In clinical practice, patients who are awake often comment that cold surgical skin disinfectant is unpleasant. This is not only a problem of patients' experience; heat loss during the disinfection process is a problem that can result in hypothermia. Evidence for the efficacy of preheated disinfection is scarce. We tested whether preheated skin disinfectant was non-inferior to room-temperature skin disinfectant on reducing bacterial colonization during pacemaker implantation. This randomized, controlled, non-inferiority trial included 220 patients allocated to skin disinfection with preheated (36 °C) or room-temperature (20 °C) chlorhexidine solution in 70 % ethanol. Cultures were obtained by swabbing at 4 time-points; 1) before skin disinfection (skin surface), 2) after skin disinfection (skin surface), 3) after the incision (subcutaneously in the wound), and 4) before suturing (subcutaneously in the wound). The absolute difference in growth between patients treated with preheated versus room-temperature skin disinfectant was zero (90 % CI -0.101 to 0.101; preheated: 30 of 105 [28.6 %] vs. room-temperature: 32 of 112 [28.6 %]). The pre-specified margin for statistical non-inferiority in the protocol was set at 10 % for the preheated disinfectant. There were no significant differences between groups regarding SSIs three month postoperatively, which occurred in 0.9 % (1 of 108) treated with preheated and 1.8 % (2 of 112) treated with room-temperature skin disinfectant. Preheated skin disinfection is non-inferior to room-temperature disinfection in bacterial reduction. We therefore suggest that preheated skin disinfection become routine in clean surgery. The study is registered at ClinicalTrials.gov (NCTO2260479).

Thermal Aging Study of a Dow Corning SE 1700 Porous Structure Made by Direct Ink Writing: 1-Year Results and Long-Term Predictions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Small, Ward; Pearson, Mark A.; Maiti, Amitesh

Dow Corning SE 1700 (reinforced polydimethylsiloxane) porous structures were made by direct ink writing (DIW). The specimens (~50% porosity) were subjected to various compressive strains (15, 30, 45%) and temperatures (room temperature, 35, 50, 70°C) in a nitrogen atmosphere (active purge) for 1 year. Compression set and load retention of the aged specimens were measured periodically during the study. Compression set increased with strain and temperature. After 1 year, specimens aged at room temperature, 35, and 50°C showed ~10% compression set (relative to the applied compressive deflection), while those aged at 70°C showed 20-40%. Due to the increasing compression set,more » load retention decreased with temperature, ranging from ~90% at room temperature to ~60-80% at 70°C. Long-term compression set and load retention at room temperature were predicted by applying time-temperature superposition (TTS). The predictions show compression set relative to the compressive deflection will be ~10-15% with ~70-90% load retention after 50 years at 15-45% strain, suggesting the material will continue to be mechanically functional. Comparison of the results to previously acquired data for cellular (M97*, M9760, M9763) and RTV (S5370) silicone foams suggests that the SE 1700 DIW porous specimens are on par with, or outperform, the legacy foams.« less

How mothers keep their babies warm.

PubMed Central

Bacon, C J; Bell, S A; Clulow, E E; Beattie, A B

1991-01-01

Details of room temperature, clothing, and bedding used by night and by day and in winter and in summer were recorded for 649 babies aged 8 to 26 weeks. Room temperature at night was significantly related to outside temperature and duration of heating. Total insulation was significantly related to outside temperature and to minimum room temperature, but there was wide variation in insulation at the same room temperature. High levels of insulation for a given room temperature were found particularly at night and in winter, and were associated with the use of thick or doubled duvets and with swaddling. At least half the babies threw off some or all of their bedding at night, and at least a quarter sweated. Younger mothers and mothers in the lower social groups put more bedclothes over their babies, and the latter also kept their rooms warmer. Many mothers kept their babies warmer during infections. PMID:2039255

Study of VTOL in ground-effect flow field including temperature effect

NASA Technical Reports Server (NTRS)

Hill, W. G.; Jenkins, R. C.; Kalemaris, S. G.; Siclari, M. J.

1982-01-01

Detailed pressure, temperature, and velocity data were obtained for twin-fan configurations in-ground-effect and flow models to aid in predicting pressures and upwash forces on aircraft surfaces were developed. For the basic experiments, 49.5 mm-diameter jets were used, oriented normal to a simulated round plane, with pressurized, heated air providing a jet. The experimental data consisted of: (1) the effect of jet height and temperature on the ground, model, and upwash pressures, and temperatures, (2) the effect of simulated aircraft surfaces on the isolated flow field, (3) the jet-induced forces on a three-dimensional body with various strakes, (4) the effects of non-uniform coannular jets. For the uniform circular jets, temperature was varied from room temperature (24 C) to 232 C. Jet total pressure was varied between 9,300 Pascals and 31,500 Pascals. For the coannular jets, intended to represent turbofan engines, fan temperature was maintained at room temperature while core temperature was varied from room temperature to 437 C. Results are presented.

Comparative studies on the room-temperature ferrielectric and ferrimagnetic Ni3TeO6-type A2FeMoO6 compounds (A = Sc, Lu)

PubMed Central

Song, Guang; Zhang, Weiyi

2016-01-01

First-principles calculations have been carried out to study the structural, electric, and magnetic properties of Ni3TeO6-type A2FeMoO6 compounds (A = Sc, Lu). Their electric and magnetic properties behave like room-temperature ferrielectric and ferrimagnetic insulators where polarization comes from the un-cancelled antiparallel dipoles of (A(1), Fe3+) and (A(2), Mo3+) ion groups, and magnetization from un-cancelled antiparallel moments of Fe3+ and Mo3+ ions. The net polarization increases with A’s ionic radius and is 7.1 and 8.7 μCcm−2 for Sc2FeMoO6 and Lu2FeMoO6, respectively. The net magnetic moment is 2 μB per formula unit. The magnetic transition temperature is estimated well above room-temperature due to the strong antiferromagnetic superexchange coupling among Fe3+ and Mo3+ spins. The estimated paraelectric to ferrielectric transition temperature is also well above room-temperature. Moreover, strong magnetoelectric coupling is also anticipated because the magnetic ions are involved both in polarization and magnetization. The fully relaxed Ni3TeO6-type A2FeMoO6 structures are free from soft-phonon modes and correspond to stable structures. As a result, Ni3TeO6-type A2FeMoO6 compounds are possible candidates for room-temperature multiferroics with large magnetization and polarization. PMID:26831406

Mechanical Properties of the TiAl IRIS Alloy

NASA Astrophysics Data System (ADS)

Voisin, Thomas; Monchoux, Jean-Philippe; Thomas, Marc; Deshayes, Christophe; Couret, Alain

2016-12-01

This paper presents a study of the mechanical properties at room and high temperature of the boron and tungsten containing IRIS alloy (Ti-48Al-2W-0.08B at. pct). This alloy was densified by Spark Plasma Sintering (SPS). The resultant microstructure consists of small lamellar colonies surrounded by γ regions containing B2 precipitates. Tensile tests are performed from room temperature to 1273 K (1000 °C). Creep properties are determined at 973 K (700 °C)/300 MPa, 1023 K (750 °C)/120 MPa, and 1023 K (750 °C)/200 MPa. The tensile strength and the creep resistance at high temperature are found to be very high compared to the data reported in the current literature while a plastic elongation of 1.6 pct is preserved at room temperature. A grain size dependence of both ductility and strength is highlighted at room temperature. The deformation mechanisms are studied by post-mortem analyses on deformed samples and by in situ straining experiments, both performed in a transmission electron microscope. In particular, a low mobility of non-screw segments of dislocations at room temperature and the activation of a mixed-climb mechanism during creep have been identified. The mechanical properties of this IRIS alloy processed by SPS are compared to those of other TiAl alloys developed for high-temperature structural applications as well as to those of similar tungsten containing alloys obtained by more conventional processing techniques. Finally, the relationships between mechanical properties and microstructural features together with the elementary deformation mechanisms are discussed.

Sensitive and Selective NH₃ Monitoring at Room Temperature Using ZnO Ceramic Nanofibers Decorated with Poly(styrene sulfonate).

PubMed

Andre, Rafaela S; Kwak, Dongwook; Dong, Qiuchen; Zhong, Wei; Correa, Daniel S; Mattoso, Luiz H C; Lei, Yu

2018-04-01

Ammonia (NH₃) gas is a prominent air pollutant that is frequently found in industrial and livestock production environments. Due to the importance in controlling pollution and protecting public health, the development of new platforms for sensing NH₃ at room temperature has attracted great attention. In this study, a sensitive NH₃ gas device with enhanced selectivity is developed based on zinc oxide nanofibers (ZnO NFs) decorated with poly(styrene sulfonate) (PSS) and operated at room temperature. ZnO NFs were prepared by electrospinning followed by calcination at 500 °C for 3 h. The electrospun ZnO NFs are characterized to evaluate the properties of the as-prepared sensing materials. The loading of PSS to prepare ZnO NFs/PSS composite is also optimized based on the best sensing performance. Under the optimal composition, ZnO NFs/PSS displays rapid, reversible, and sensitive response upon NH₃ exposure at room temperature. The device shows a dynamic linear range up to 100 ppm and a limit of detection of 3.22 ppm and enhanced selectivity toward NH₃ in synthetic air, against NO₂ and CO, compared to pure ZnO NFs. Additionally, a sensing mechanism is proposed to illustrate the sensing performance using ZnO NFs/PSS composite. Therefore, this study provides a simple methodology to design a sensitive platform for NH₃ monitoring at room temperature.

Fluorescence behaviour of 5,10-methenyltetrahydrofolate, 10-formyltetrahydrofolate, 10-formyldihydrofolate, and 10-formylfolate in aqueous solution at pH 8

NASA Astrophysics Data System (ADS)

Tyagi, A.; Penzkofer, A.; Batschauer, A.; Wolf, E.

2009-06-01

The fluorescence spectroscopic behaviour of (6R,S)-5,10-methenyltetrahydrofolate (MTHF), (6R,S)-10-formyltetrahydrofolate (10-HCO-H4folate), 10-formyldihydrofolate (10-HCO-H2folate), and 10-formylfolate (10-HCO-folate) in aqueous Tris-HCl buffer at pH 8 is studied. MTHF and 10-HCO-folate were commercially available. 10-HCO-H4folate was prepared from MTHF by hydrolysis at room temperature under anaerobic conditions. 10-HCO-H2folate was prepared by oxidation of 10-HCO-H4folate under aerobic conditions. Fluorescence quantum distributions at room temperature and fluorescence signal decays at room temperature and liquid nitrogen temperature were measured. The fluorescence lifetimes determined at room temperature (liquid nitrogen temperature) are 10 ps (2.9 ns) for MTHF, 38 ps (3.7 ns) for 10-HCO-H4folate, 80 ps (10.5 ns) for 10-HCO-H2folate, and 7.1 ns (20 ns) for 10-HCO-folate. The results are discussed in terms of dyadic (pterin-benzoyl-glutamate) photo-induced electron transfer and dyadic fluorescent dynamics.

Study on room temperature gas-sensing performance of CuO film-decorated ordered porous ZnO composite by In2O3 sensitization

NASA Astrophysics Data System (ADS)

Li, Tian-tian; Bao, Na; Geng, Ai-fang; Yu, Hui; Yang, Ying; Dong, Xiang-ting

2018-02-01

For the first time, ordered mesoporous ZnO nanoparticles have been synthesized by a template method. The electroplating after chemical plating method was creatively used to form copper film on the surface of the prepared ZnO, and then a CuO film-decorated ordered porous ZnO composite (CuO/ZnO) was obtained by a high-temperature oxidation method. In2O3 was loaded into the prepared CuO film-ZnO by an ultrasonic-assisted method to sensitize the room temperature gas-sensing performance of the prepared CuO/ZnO materials. The doped In2O3 could effectively improve the gas-sensing properties of the prepared materials to nitrogen oxides (NOx) at room temperature. The 1% In2O3 doped CuO/ZnO sample (1 wt% In2O3-CuO/ZnO) showed the best gas-sensing properties whose response to 100 ppm NOx reached 82%, and the detectable minimum concentration reached 1 ppm at room temperature. The prepared materials had a good selectivity, better response, very low detection limit, and high sensitivity to NOx gas at room temperature, which would have a great development space in the gas sensor field and a great research value.

Hydroxyl Radical Fluorescence and Quantum Yield Following Lyman-α Photoexcitation of Water Vapor in a Room Temperature Cell and Cooled in a Supersonic Expansion.

PubMed

Young, Justin W; Booth, Ryan S; Vogelhuber, Kristen M; Stearns, Jaime A; Annesley, Christopher J

2018-06-28

Photoexcitation of water by Lyman-α (121.6 nm) induces a dissociation reaction that produces OH(A 2 Σ + ) + H. Despite this reaction being part of numerous studies, a combined understanding of the product and fluorescence yields is still lacking. Here, the rotational and vibrational distributions of OH(A) are determined from dispersed fluorescence following photoexcitation of both room-temperature and jet-cooled water vapor, for the first time in the same experiment. This work compares new data of state-resolved fluorescence with literature molecular branching ratios and brings previous studies into agreement through careful consideration of OH(A) fluorescent and predissociation lifetimes and confirms a fluorescent quantum yield of 8%. Comparison of the room-temperature and jet-cooled OH(A) populations indicate the temperature of H 2 O prior to excitation has subtle effects on the OH(A) population distribution, such as altering the rotational distribution in the ν' = 0 population and affecting the population in the ν' = 1 state. These results indicate jet-cooled water vapor may have a 1% higher fluorescence quantum yield compared to room-temperature water vapor.

Room Temperature Curing Resin Systems for Graphite/Epoxy Composite Repair.

DTIC Science & Technology

1979-12-01

ROOM TEMPERATURE CURING RESIN SYSTEMS FOR GRAPHITE/EPOXY COMPOS--ETC(UI DEC 79 0 J CRABTREE N62269-79-C-G224 UNCLASSIFIE O80-46 NADC -781 1-6 NL END...Room Temperature Curing Resin Sys-U3 linal for Graphite/Epoxy Composite Repair •.Dec *79 NOR- -46h: V111IT NUM8ER(s) 4362269-79- ,722 S. PERFORMING...repair, composite repair room temperature cure resin , moderate temperature cure resins , epoxies, adhesives, vinyl eater polymers, anaerobic curing polymers

Magnetism of Amorphous and Nano-Crystallized Dc-Sputter-Deposited MgO Thin Films

PubMed Central

Mahadeva, Sreekanth K.; Fan, Jincheng; Biswas, Anis; Sreelatha, K.S.; Belova, Lyubov; Rao, K.V.

2013-01-01

We report a systematic study of room-temperature ferromagnetism (RTFM) in pristine MgO thin films in their amorphous and nano-crystalline states. The as deposited dc-sputtered films of pristine MgO on Si substrates using a metallic Mg target in an O2 containing working gas atmosphere of (N2 + O2) are found to be X-ray amorphous. All these films obtained with oxygen partial pressure (PO2) ~10% to 80% while maintaining the same total pressure of the working gas are found to be ferromagnetic at room temperature. The room temperature saturation magnetization (MS) value of 2.68 emu/cm3 obtained for the MgO film deposited in PO2 of 10% increases to 9.62 emu/cm3 for film deposited at PO2 of 40%. However, the MS values decrease steadily for further increase of oxygen partial pressure during deposition. On thermal annealing at temperatures in the range 600 to 800 °C, the films become nanocrystalline and as the crystallite size grows with longer annealing times and higher temperature, MS decreases. Our study clearly points out that it is possible to tailor the magnetic properties of thin films of MgO. The room temperature ferromagnetism in MgO films is attributed to the presence of Mg cation vacancies. PMID:28348346

Delayed elastic effects in the glass ceramics Zerodur and ULE at room temperature.

PubMed

Pepi, J W; Golini, D

1991-08-01

The time-dependent phenomenon of delayed elasticity was studied at room temperature and is presented here for Zerodur and ULE. The effect is believed to be related to the alkali oxide content of the glass and to the rearrangement of the ion groups within the structure during stress.

Study of the heavy atom-induced room temperature phosphorescence properties of melatonin and its analytical application

NASA Astrophysics Data System (ADS)

Amjadi, Mohammad; Manzoori, Jamshid L.; Miller, James N.

2006-02-01

Liquid phase room temperature phosphorescence (RTP) properties of melatonin were studied using heavy atom induced-room temperature phosphorescence (HAI-RTP) technique. 1.2 M potassium iodide was used as a heavy atom reagent together with 0.002 M sodium sulphite as deoxygenating agent to produce the RTP signal. The maximum phosphorescence emission and excitation wavelengths of melatonin were 290 and 457 nm, respectively. The effect of potassium iodide concentration on the RTP lifetime of melatonin was also investigated and based on the results, the rate constants for phosphorescence decay ( kp) and radiationless deactivation through reaction with heavy atom ( kh) were determined. Based on the obtained results, a simple and sensitive room temperature phosphorimetric method was developed for the determination of melatonin. The method allowed the determination of 10.0-200 ng ml -1 melatonin in aqueous solution with the limits of detection and quantification of 3.6 and 12 ng ml -1, respectively. The proposed method was satisfactorily applied to the determination of melatonin in commercial pharmaceutical formulations.

Weak magnetism of Aurivillius-type multiferroic thin films probed by polarized neutron reflectivity

NASA Astrophysics Data System (ADS)

Zhai, Xiaofang; Grutter, Alexander J.; Yun, Yu; Cui, Zhangzhang; Lu, Yalin

2018-04-01

Unambiguous magnetic characterization of room-temperature multiferroic materials remains challenging due in part to the difficulty of distinguishing their very weak ferromagnetism from magnetic impurity phases and other contaminants. In this study, we used polarized neutron reflectivity to probe the magnetization of B i6FeCoT i3O18 and LaB i5FeCoT i3O18 in their epitaxial thin films while eliminating a variety of impurity contributions. Our results show that LaB i5FeCoT i3O18 exhibits a magnetization of about 0.016 ±0.027 μB/Fe -Co pair at room temperature, while the B i6FeCoT i3O18 thin film only exhibits a weak magnetic moment below room temperature, with a saturation magnetization of 0.049 ±0.015 μB/Fe -Co pair at 50 K. This polarized-neutron-reflectivity study places an upper magnetization limit on the matrix material of the magnetically doped Aurivillius oxides and helps to clarify the true mechanism behind the room-temperature magnetic performance.

[Study on the stability of tetrandrine microsphere].

PubMed

Cheng, Guohu; Luo, Jiabo

2005-05-01

To study the stability of Tetrandrine Microsphere. Higher speed test and room temperature test were adopted to investigate the indexes, such as properties of appearance, amount of medicine loaded, seal rate, seepage rate, microbial stability, etc. Through the test of six months, properties of appearance, amount of medicine loaded, seal rate, seepage rate, microbial stability have not obviously change. But after testing for 6 months with higher temperature, the seal rate was reduced, and the seepage rate was increased. Tetrandrine microsphere is steady under the room temperature condition, but is unstable to hot, and ought to keep in conformity with low-temperature.

Reducing pain with genetic amniocentesis-A randomized trial of subfreezing versus room temperature needles.

PubMed

Wax, Joseph R; Pinette, Michael G; Carpenter, Molly; Chard, Renée; Blackstone, Jacquelyn; Cartin, Angelina

2005-10-01

To determine whether pain associated with second trimester genetic amniocentesis is decreased by using subfreezing rather than room temperature needles. Subjects were randomized to a -14 degrees C or room temperature (20-22 degrees C) 22-gauge spinal needle. Patients, blinded to allocation, recorded anticipated and actual pain before and after the procedure, respectively, using a 0-10 visual analog scale with 0 = no pain and 10 = excruciating pain. Thirty-three subjects were randomized to room temperature and 29 subjects to subfreezing needles. Anticipated pain was similar in room temperature, 5.1 +/- 1.7, and subfreezing groups, 4.9 +/- 2.0, respectively (p = 0.6). Actual pain was also similar in the room temperature, 3.6 +/- 2.0, and subfreezing groups, 2.8 +/- 2.0, respectively (p = 0.14). Similar numbers of subjects in the room temperature and subfreezing groups reported less actual pain (20 vs. 18), greater actual pain (4 vs. 4) or no difference in pain (9 vs. 5) than anticipated (p = 0.6). A subfreezing 22-gauge spinal needle does not decrease perceived pain associated with second trimester genetic amniocentesis.

Room Temperature and Elevated Temperature Composite Sandwich Joint Testing

NASA Technical Reports Server (NTRS)

Walker, Sandra P.

1998-01-01

Testing of composite sandwich joint elements has been completed to verify the strength capacity of joints designed to carry specified running loads representative of a high speed civil transport wing. Static tension testing at both room and an elevated temperature of 350 F and fatigue testing at room temperature were conducted to determine strength capacity, fatigue life, and failure modes. Static tension test results yielded failure loads above the design loads for the room temperature tests, confirming the ability of the joint concepts tested to carry their design loads. However, strength reductions as large as 30% were observed at the elevated test temperature, where all failure loads were below the room temperature design loads for the specific joint designs tested. Fatigue testing resulted in lower than predicted fatigue lives.

Ambient temperature influences the neural benefits of exercise.

PubMed

Maynard, Mark E; Chung, Chasity; Comer, Ashley; Nelson, Katharine; Tran, Jamie; Werries, Nadja; Barton, Emily A; Spinetta, Michael; Leasure, J Leigh

2016-02-15

Many of the neural benefits of exercise require weeks to manifest. It would be useful to accelerate onset of exercise-driven plastic changes, such as increased hippocampal neurogenesis. Exercise represents a significant challenge to the brain because it produces heat, but brain temperature does not rise during exercise in the cold. This study tested the hypothesis that exercise in cold ambient temperature would stimulate hippocampal neurogenesis more than exercise in room or hot conditions. Adult female rats had exercise access 2h per day for 5 days at either room (20 °C), cold (4.5 °C) or hot (37.5 °C) temperature. To label dividing hippocampal precursor cells, animals received daily injections of BrdU. Brains were immunohistochemically processed for dividing cells (Ki67+), surviving cells (BrdU+) and new neurons (doublecortin, DCX) in the hippocampal dentate gyrus. Animals exercising at room temperature ran significantly farther than animals exercising in cold or hot conditions (room 1490 ± 400 m; cold 440 ± 102 m; hot 291 ± 56 m). We therefore analyzed the number of Ki67+, BrdU+ and DCX+ cells normalized for shortest distance run. Contrary to our hypothesis, exercise in either cold or hot conditions generated significantly more Ki67+, BrdU+ and DCX+ cells compared to exercise at room temperature. Thus, a limited amount of running in either cold or hot ambient conditions generates more new cells than a much greater distance run at room temperature. Taken together, our results suggest a simple means by which to augment exercise effects, yet minimize exercise time. Copyright © 2015 Elsevier B.V. All rights reserved.

Energy transition characterization of 1.18 and 1.3 {mu}m bands of bismuth fiber by spectroscopy of the transient oscillations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gumenyuk, Regina; Okhotnikov, Oleg G.; Golant, Konstantin

2011-05-09

The experimental evidence of laser transition type in bismuth-doped silica fibers operating at different spectral bands is presented. Spectrally resolved transient (relaxation) oscillations studied for a Bi-doped fiber laser at room and liquid-nitrogen temperatures allow to identify the three- and four-level energy bands. 1.18 {mu}m short-wavelength band is found to be a three-level system at room temperature with highly populated terminal energy level of laser transition. The depopulation of ground level by cooling the fiber down to liquid-nitrogen temperature changes the transition to four-level type. Four-level energy transition distinguished at 1.32 {mu}m exhibits the net gain at room temperature.

Preliminary neutron and X-ray crystallographic studies of equine cyanomethemoglobin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kovalevsky, A.Y.; Fisher, S.Z.; Seaver, S.

2010-08-18

Room-temperature and 100 K X-ray and room-temperature neutron diffraction data have been measured from equine cyanomethemoglobin to 1.7 {angstrom} resolution using a home source, to 1.6 {angstrom} resolution on NE-CAT at the Advanced Photon Source and to 2.0 {angstrom} resolution on the PCS at Los Alamos Neutron Science Center, respectively. The cyanomethemoglobin is in the R state and preliminary room-temperature electron and neutron scattering density maps clearly show the protonation states of potential Bohr groups. Interestingly, a water molecule that is in the vicinity of the heme group and coordinated to the distal histidine appears to be expelled from thismore » site in the low-temperature structure.« less

Microcontroller based automatic temperature control for oyster mushroom plants

NASA Astrophysics Data System (ADS)

Sihombing, P.; Astuti, T. P.; Herriyance; Sitompul, D.

2018-03-01

In the cultivation of Oyster Mushrooms need special treatment because oyster mushrooms are susceptible to disease. Mushroom growth will be inhibited if the temperature and humidity are not well controlled because temperature and inertia can affect mold growth. Oyster mushroom growth usually will be optimal at temperatures around 22-28°C and humidity around 70-90%. This problem is often encountered in the cultivation of oyster mushrooms. Therefore it is very important to control the temperature and humidity of the room of oyster mushroom cultivation. In this paper, we developed an automatic temperature monitoring tool in the cultivation of oyster mushroom-based Arduino Uno microcontroller. We have designed a tool that will control the temperature and humidity automatically by Android Smartphone. If the temperature increased more than 28°C in the room of mushroom plants, then this tool will turn on the pump automatically to run water in order to lower the room temperature. And if the room temperature of mushroom plants below of 22°C, then the light will be turned on in order to heat the room. Thus the temperature in the room oyster mushrooms will remain stable so that the growth of oyster mushrooms can grow with good quality.

Survival of Salmonella and Staphylococcus aureus in mexican red salsa in a food service setting.

PubMed

Franco, Wendy; Hsu, Wei-Yea; Simonne, Amarat H

2010-06-01

Mexican red salsa is one of the most common side dishes in Mexican cuisine. According to data on foodborne illnesses collected by the Centers for Disease Control and Prevention, salsa was associated with 70 foodborne illness outbreaks between 1990 and 2006. Salsa ingredients such as tomatoes, cilantro, and onions often have been implicated in foodborne illness outbreaks. Mexican-style restaurants commonly prepare a large batch of red salsa, store it at refrigeration temperatures, and then serve it at room temperature. Salmonella is one of the top etiologies in foodborne illness outbreaks associated with salsa, and our preliminary studies revealed the consistent presence of Staphylococcus aureus in restaurant salsa. In the present study, we evaluated the survival of Salmonella Enteritidis and S. aureus inoculated into restaurant-made salsa samples stored at ambient (20 degrees C) and refrigeration (4 degrees C) temperatures. These test temperature conditions represent best-case and worst-case scenarios in restaurant operations. Salmonella survived in all samples stored at room temperature, but S. aureus populations significantly decreased after 24 h of storage at room temperature. No enterotoxin was detected in samples inoculated with S. aureus at 6.0 log CFU/g. Both microorganisms survived longer in refrigerated samples than in samples stored at room temperature. Overall, both Salmonella and S. aureus survived a sufficient length of time in salsa to pose a food safety risk.

Temperature effects on the mechanical properties of annealed and HERF 304L stainless steel.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antoun, Bonnie R.

2004-11-01

The effect of temperature on the tensile properties of annealed 304L stainless steel and HERF 304L stainless steel forgings was determined by completing experiments over the moderate range of -40 F to 160 F. Temperature effects were more significant in the annealed material than the HERF material. The tensile yield strength of the annealed material at -40 F averaged twenty two percent above the room temperature value and at 160 F averaged thirteen percent below. The tensile yield strength for the three different geometry HERF forgings at -40 F and 160 F changed less than ten percent from room temperature.more » The ultimate tensile strength was more temperature dependent than the yield strength. The annealed material averaged thirty six percent above and fourteen percent below the room temperature ultimate strength at -40 F and 160 F, respectively. The HERF forgings exhibited similar, slightly lower changes in ultimate strength with temperature. For completeness and illustrative purposes, the stress-strain curves are included for each of the tensile experiments conducted. The results of this study prompted a continuation study to determine tensile property changes of welded 304L stainless steel material with temperature, documented separately.« less

Fast detection and low power hydrogen sensor using edge-oriented vertically aligned 3-D network of MoS2 flakes at room temperature

NASA Astrophysics Data System (ADS)

Agrawal, A. V.; Kumar, R.; Venkatesan, S.; Zakhidov, A.; Zhu, Z.; Bao, Jiming; Kumar, Mahesh; Kumar, Mukesh

2017-08-01

The increased usage of hydrogen as a next generation clean fuel strongly demands the parallel development of room temperature and low power hydrogen sensors for their safety operation. In this work, we report strong evidence for preferential hydrogen adsorption at edge-sites in an edge oriented vertically aligned 3-D network of MoS2 flakes at room temperature. The vertically aligned edge-oriented MoS2 flakes were synthesised by a modified CVD process on a SiO2/Si substrate and confirmed by Scanning Electron Microscopy. Raman spectroscopy and PL spectroscopy reveal the signature of few-layer MoS2 flakes in the sample. The sensor's performance was tested from room temperature to 150 °C for 1% hydrogen concentration. The device shows a fast response of 14.3 s even at room temperature. The sensitivity of the device strongly depends on temperature and increases from ˜1% to ˜11% as temperature increases. A detail hydrogen sensing mechanism was proposed based on the preferential hydrogen adsorption at MoS2 edge sites. The proposed gas sensing mechanism was verified by depositing ˜2-3 nm of ZnO on top of the MoS2 flakes that partially passivated the edge sites. We found a decrease in the relative response of MoS2-ZnO hybrid structures. This study provides a strong experimental evidence for the role of MoS2 edge-sites in the fast hydrogen sensing and a step closer towards room temperature, low power (0.3 mW), hydrogen sensor development.

Tensile Strength and Microstructure of Al2O3-ZrO2 Hypo-Eutectic Fibers Studied

NASA Technical Reports Server (NTRS)

Farmer, Serene C.; Sayir, Ali

2001-01-01

Oxide eutectics offer high-temperature strength retention and creep resistance in oxidizing environments. Al2O3-ZrO2 eutectic strengths have been studied since the 1970's. Directionally solidified oxide eutectics exhibit improved resistance to slow crack growth and excellent strength retention at high temperatures up to 1400 C. Materials studied typically contain Y2O3 to metastably retain the high-temperature cubic and tetragonal polymorphs at room temperature. Al2O3-ZrO2 is of fundamental interest for creep studies because it combines a creep-resistant material, Al2O3, with a very low creep resistance material, ZrO2. Results on mechanical properties and microstructures of these materials will be used to define compositions for creep testing in future work. Substantial variations from the eutectic alumina to zirconia ratio can be tolerated without a loss in room-temperature strength. The effect of increasing Y2O3 addition on the room-temperature tensile strength of an Al2O3-ZrO2 material containing excess Al2O3 was examined at the NASA Glenn Research Center, where the materials were grown using Glenn's world-class laser growth facilities.

Potential of energy harvesting in barium titanate based laminates from room temperature to cryogenic/high temperatures: measurements and linking phase field and finite element simulations

NASA Astrophysics Data System (ADS)

Narita, Fumio; Fox, Marina; Mori, Kotaro; Takeuchi, Hiroki; Kobayashi, Takuya; Omote, Kenji

2017-11-01

This paper studies the energy harvesting characteristics of piezoelectric laminates consisting of barium titanate (BaTiO3) and copper (Cu) from room temperature to cryogenic/high temperatures both experimentally and numerically. First, the output voltages of the piezoelectric BaTiO3/Cu laminates were measured from room temperature to a cryogenic temperature (77 K). The output power was evaluated for various values of load resistance. The results showed that the maximum output power density is approximately 2240 nW cm-3. The output voltages of the BaTiO3/Cu laminates were also measured from room temperature to a higher temperature (333 K). To discuss the output voltages of the BaTiO3/Cu laminates due to temperature changes, phase field and finite element simulations were combined. A phase field model for grain growth was used to generate grain structures. The phase field model was then employed for BaTiO3 polycrystals, coupled with the time-dependent Ginzburg-Landau theory and the oxygen vacancies diffusion, to calculate the temperature-dependent piezoelectric coefficient and permittivity. Using these properties, the output voltages of the BaTiO3/Cu laminates from room temperature to both 77 K and 333 K were analyzed by three dimensional finite element methods, and the results are presented for several grain sizes and oxygen vacancy densities. It was found that electricity in the BaTiO3 ceramic layer is generated not only through the piezoelectric effect caused by a thermally induced bending stress but also by the temperature dependence of the BaTiO3 piezoelectric coefficient and permittivity.

Finite-Temperature Hydrogen Adsorption/Desorption Thermodynamics Driven by Soft Vibration Modes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Woo, Sung-Jae; Lee, Eui-Sup; Yoon, Mina

2013-01-01

It is widely accepted that room-temperature hydrogen storage on nanostructured or porous materials requires enhanced dihydrogen adsorption. In this work we reveal that room-temperature hydrogen storage is possible not only by the enhanced adsorption, but also by making use of the vibrational free energy from soft vibration modes. These modes exist for example in the case of metallo-porphyrin-incorporated graphenes (M-PIGs) with out-of-plane ( buckled ) metal centers. There, the in-plane potential surfaces are flat because of multiple-orbital-coupling between hydrogen molecules and the buckled-metal centers. This study investigates the finite-temperature adsorption/desorption thermodynamics of hydrogen molecules adsorbed on M-PIGs by employing first-principlesmore » total energy and vibrational spectrum calculations. Our results suggest that the current design strategy for room-temperature hydrogen storage materials should be modified by explicitly taking finite-temperature vibration thermodynamics into account.« less

Mechanical Behaviour of 304 Austenitic Stainless Steel Processed by Room Temperature Rolling

NASA Astrophysics Data System (ADS)

Singh, Rahul; Goel, Sunkulp; Verma, Raviraj; Jayaganthan, R.; Kumar, Abhishek

2018-03-01

To study the effect of room temperature rolling on mechanical properties of 304 Austenitic Stainless Steel, the as received 304 ASS was rolled at room temperature for different percentage of plastic deformation (i.e. 30, 50, 70 and 90 %). Microstructural study, tensile and hardness tests were performed in accordance with ASTM standards to study the effect of rolling. The ultimate tensile strength (UTS) and hardness of a rolled specimen have enhanced with rolling. The UTS has increased from 693 MPa (as received) to 1700 MPa (after 90% deformation). The improvement in UTS of processed samples is due to combined effect of grain refinement and stress induced martensitic phase transformation. The hardness values also increases from 206 VHN (as received) to 499 VHN (after 90% deformation). Magnetic measurements were also conducted to confirm the formation of martensitic phase.

Using sieving and pretreatment to separate plastics during end-of-life vehicle recycling.

PubMed

Stagner, Jacqueline A; Sagan, Barsha; Tam, Edwin Kl

2013-09-01

Plastics continue to be a challenge for recovering materials at the end-of-life for vehicles. However, it may be possible to improve the recovery of plastics by exploiting material characteristics, such as shape, or by altering their behavior, such as through temperature changes, in relation to recovery processes and handling. Samples of a 2009 Dodge Challenger front fascia were shredded in a laboratory-scale hammer mill shredder. A 2 × 2 factorial design study was performed to determine the effect of sample shape (flat versus curved) and sample temperature (room temperature versus cryogenic temperature) on the size of the particles exiting from the shredder. It was determined that sample shape does not affect the particle size; however, sample temperature does affect the particle size. At cryogenic temperatures, the distribution of particle sizes is much narrower than at room temperature. Having a more uniform particle size could make recovery of plastic particles, such as these more efficient during the recycling of end-of-life vehicles. Samples of Chrysler minivan headlights were also shredded at room temperature and at cryogenic temperatures. The size of the particles of the two different plastics in the headlights is statistically different both at room temperature and at cryogenic temperature, and the particles are distributed narrowly. The research suggests that incremental changes in end-of-life vehicle processing could be effective in aiding materials recovery.

Room temperature organic magnets derived from sp3 functionalized graphene.

PubMed

Tuček, Jiří; Holá, Kateřina; Bourlinos, Athanasios B; Błoński, Piotr; Bakandritsos, Aristides; Ugolotti, Juri; Dubecký, Matúš; Karlický, František; Ranc, Václav; Čépe, Klára; Otyepka, Michal; Zbořil, Radek

2017-02-20

Materials based on metallic elements that have d orbitals and exhibit room temperature magnetism have been known for centuries and applied in a huge range of technologies. Development of room temperature carbon magnets containing exclusively sp orbitals is viewed as great challenge in chemistry, physics, spintronics and materials science. Here we describe a series of room temperature organic magnets prepared by a simple and controllable route based on the substitution of fluorine atoms in fluorographene with hydroxyl groups. Depending on the chemical composition (an F/OH ratio) and sp 3 coverage, these new graphene derivatives show room temperature antiferromagnetic ordering, which has never been observed for any sp-based materials. Such 2D magnets undergo a transition to a ferromagnetic state at low temperatures, showing an extraordinarily high magnetic moment. The developed theoretical model addresses the origin of the room temperature magnetism in terms of sp 2 -conjugated diradical motifs embedded in an sp 3 matrix and superexchange interactions via -OH functionalization.

Room temperature organic magnets derived from sp3 functionalized graphene

PubMed Central

Tuček, Jiří; Holá, Kateřina; Bourlinos, Athanasios B.; Błoński, Piotr; Bakandritsos, Aristides; Ugolotti, Juri; Dubecký, Matúš; Karlický, František; Ranc, Václav; Čépe, Klára; Otyepka, Michal; Zbořil, Radek

2017-01-01

Materials based on metallic elements that have d orbitals and exhibit room temperature magnetism have been known for centuries and applied in a huge range of technologies. Development of room temperature carbon magnets containing exclusively sp orbitals is viewed as great challenge in chemistry, physics, spintronics and materials science. Here we describe a series of room temperature organic magnets prepared by a simple and controllable route based on the substitution of fluorine atoms in fluorographene with hydroxyl groups. Depending on the chemical composition (an F/OH ratio) and sp3 coverage, these new graphene derivatives show room temperature antiferromagnetic ordering, which has never been observed for any sp-based materials. Such 2D magnets undergo a transition to a ferromagnetic state at low temperatures, showing an extraordinarily high magnetic moment. The developed theoretical model addresses the origin of the room temperature magnetism in terms of sp2-conjugated diradical motifs embedded in an sp3 matrix and superexchange interactions via –OH functionalization. PMID:28216636

The electrical properties of 60 keV zinc ions implanted into semi-insulating gallium arsenide

NASA Technical Reports Server (NTRS)

Littlejohn, M. A.; Anikara, R.

1972-01-01

The electrical behavior of zinc ions implanted into chromium-doped semiinsulating gallium arsenide was investigated by measurements of the sheet resistivity and Hall effect. Room temperature implantations were performed using fluence values from 10 to the 12th to 10 to the 15th power/sq cm at 60 keV. The samples were annealed for 30 minutes in a nitrogen atmosphere up to 800 C in steps of 200 C and the effect of this annealing on the Hall effect and sheet resistivity was studied at room temperature using the Van der Pauw technique. The temperature dependence of sheet resistivity and mobility was measured from liquid nitrogen temperature to room temperature. Finally, a measurement of the implanted profile was obtained using a layer removal technique combined with the Hall effect and sheet resistivity measurements.

Identification and quantification of ethyl carbamate occurring in urea complexation processes commonly utilized for polyunsaturated fatty acid concentration.

PubMed

Vázquez, Luis; Prados, Isabel M; Reglero, Guillermo; Torres, Carlos F

2017-08-15

The concentration of polyunsaturated fatty acids by formation of urea adducts from three different sources was studied to elucidate the formation of ethyl carbamates in the course of these procedures. Two different methodologies were performed: with ethanol at high temperature and with hexane/ethanol mixtures at room temperature. It was proved that the amount of urethanes generated at high temperature was higher than at room temperature. Besides, subsequent washing steps of the PUFA fraction with water were efficient to remove the urethanes from the final products. The methodology at room temperature with 0.4mL ethanol and 3g urea provided good relationship between concentration and yield of the main bioactive PUFA, with the lowest formation of ethyl carbamates in the process. Copyright © 2017 Elsevier Ltd. All rights reserved.

Research Investigation Directed Toward Extending the Useful Range of the Electromagnetic Spectrum.

DTIC Science & Technology

1987-12-31

spectrometer ions photoionic emission threshold low temperature processing low energy ion beam silicon oxidation sputtering of silicon dioxide germanium...Osgood, "Optically-Induced, Room- Temperature Oxidation of Gallium Arsenide," Mat. Res. Soc. Symp. Proc. 75(1987):251-255. P. D. Brewer and R. M. Osgood... oxide films (40-70 A) at room temperature which are suitable for MOSFET devices, has been extensively studied experimentally and theoretically. The

Living Membranes as Environmental Detectors

DTIC Science & Technology

2016-02-19

followed. Initial studies were conducted for 30 days of storage at room temperature and 4⁰C. Results indicate that the living membrane is stable...4⁰C or room temperature in wet or lyophilized form. Freeze-dried mat Wet pellicle 4oC RT 4oC RT Figure 13: Stability of RFP Living Membrane...physically robust format able to withstand extremes of temperature , humidity, and other environmental variables The living membrane systems under

Effects of room temperature aging on two cryogenic temperature sensor models used in aerospace applications

NASA Astrophysics Data System (ADS)

Courts, S. Scott; Krause, John

2012-06-01

Cryogenic temperature sensors used in aerospace applications are typically procured far in advance of the mission launch date. Depending upon the program, the temperature sensors may be stored at room temperature for extended periods as installation and groundbased testing can take years before the actual flight. The effects of long term storage at room temperature are sometimes approximated by the use of accelerated aging at temperatures well above room temperature, but this practice can yield invalid results as the sensing material and/or electrical contacting method can be increasingly unstable with higher temperature exposure. To date, little data are available on the effects of extended room temperature aging on sensors commonly used in aerospace applications. This research examines two such temperature sensors models - the Lake Shore Cryotronics, Inc. model CernoxTM and DT-670-SD temperature sensors. Sample groups of each model type have been maintained for ten years or longer with room temperature storage between calibrations. Over an eighteen year period, the CernoxTM temperature sensors exhibited a stability of better than ±20 mK for T<30 K and better than ±0.1% of temperature for T>30 K. Over a ten year period the model DT-670-SD sensors exhibited a stability of better than ±140 mK for T<25 K and better than ±75 mK for T>25 K.

Association between diurnal temperature range and respiratory tract infections.

PubMed

Ge, Wen Zhen; Xu, Feng; Zhao, Zhuo Hui; Zhao, Jin Zhuo; Kan, Hai Dong

2013-03-01

This study aimed to assess the association between emergency-room visits for respiratory tract infection (RTI) with diurnal temperature range (DTR), a weather parameter closely associated with urbanization and global climate change. We conducted a semiparametric time-series analysis to estimate the percentage increase in emergency-room visits for RTI associated with changes in DTR after adjustment for daily weather conditions (temperature and relative humidity) and outdoor air pollution. DTR was significantly associated with daily emergency-room visits for RTI. An increase of 1 °C in the current-day (L0) and in the 2-day moving average (L01) DTR corresponded to a 0.94% [95% confidence interval (CI), 0.34%-1.55%] and 2.08% (95% CI, 1.24%-2.93%) increase in emergency-room visits for RTI, respectively. DTR was associated with increased risk of RTI. More studies are needed to understand the impact of DTR on respiratory health. Copyright © 2013 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

The use of pH adjusted lignocaine in controlling operative pain in the day surgery unit: a prospective, randomised trial.

PubMed

Fitton, A R; Ragbir, M; Milling, M A

1996-09-01

We report the results of a randomised, case matched, controlled, double blind study on 40 patients undergoing correction of their prominent ears, comparing efficacy of pH adjusted lignocaine to lignocaine alone in controlling operative pain. Each patient received commercial lignocaine in one ear and the same preparation reconstituted with 1 ml of 8.4% sodium bicarbonate in the other ear according to our randomisation protocol. 30 patients were studied to compare the difference between the buffered and commercial preparation infiltrated at room temperature. A further 10 patients were studied to assess the benefit the buffered preparation at room temperature had over commercial lignocaine warmed to body temperature. Linear analogue pain scores for discomfort at infiltration and during the operation itself were analysed. Buffered lignocaine imparts a significant reduction in pain on infiltration, compared to the commercial preparation at both room and body temperature. Both preparations were equally effective in obliterating pain during the operation itself.

Room temperature ferromagnetism in Mn-doped NiO nanoparticles

NASA Astrophysics Data System (ADS)

Layek, Samar; Verma, H. C.

2016-01-01

Mn-doped NiO nanoparticles of the series Ni1-xMnxO (x=0.00, 0.02, 0.04 and 0.06) are successfully synthesized using a low temperature hydrothermal method. Samples up to 6% Mn-doping are single phase in nature as observed from powder x-ray diffraction (XRD) studies. Rietveld refinement of the XRD data shows that all the single phase samples crystallize in the NaCl like fcc structure with space group Fm-3m. Unit cell volume decreases with increasing Mn-doping. Pure NiO nanoparticles show weak ferromagnetism, may be due to nanosize nature. Introduction of Mn within NiO lattice improves the magnetic properties significantly. Room temperature ferromagnetism is found in all the doped samples whereas the magnetization is highest for 2% Mn-doping and then decreases with further doping. The ZFC and FC branches in the temperature dependent magnetization separate well above 350 K indicating transition temperature well above room temperature for 2% Mn-doped NiO Nanoparticle. The ferromagnetic Curie temperature is found to be 653 K for the same sample as measured by temperature dependent magnetization study using vibrating sample magnetometer (VSM) in high vacuum.

Validation of time and temperature values as critical limits for Salmonella and background flora growth during the production of fresh ground and boneless pork products.

PubMed

Mann, J E; Smith, L; Brashears, M M

2004-07-01

To provide pork processors with valuable data to validate the critical limits set for temperature during pork fabrication and grinding, a study was conducted to determine the growth of Salmonella serotypes and background flora at various temperatures. Growth of Salmonella Typhimurium and Salmonella Enteritidis and of background flora was monitored in ground pork and boneless pork chops held at various temperatures to determine growth patterns. Case-ready modified atmosphere packaged ground pork and fresh whole pork loins were obtained locally. Boneless chops and ground pork were inoculated with a cocktail mixture of streptomycin-resistant Salmonella to facilitate recovery in the presence of background flora. Samples were held at 4.4, 7.2C, and 10 degrees C and at room temperature (22.2 to 23.3 degrees C) to mimic typical processing and holding temperatures observed in pork processing environments. Salmonella counts were determined at regular intervals over 12 and 72 h for both room and refrigeration temperatures. No significant growth of Salmonella (P < 0.05) was observed in boneless pork chops held at refrigeration temperatures. However, Salmonella in boneless pork chops held at room temperature had grown significantly by 8 h. Salmonella grew at faster rates in ground pork. Significant growth was observed at 6, 24. and 72 h when samples were held at room temperature, 10 degrees C, and 7.2 degrees C, respectively. No significant growth was observed at 4.4 degrees C. Background flora in ground pork samples increased significantly after 10 h at room temperature and after 12 h for samples held at 10 and 7.2 degrees C. Background flora in samples held at refrigeration temperatures did not increase until 72 h. Background flora in the boneless chops increased significantly after 6 h at room temperature and after 24 h when held at 10 and 4.4 degrees C. These results illustrate that meat processors can utilize a variety of time and temperature combinations as critical limits to minimize Salmonella growth during production and storage of raw pork products.

An 57Fe Mössbauer study of the ordinary chondrite meteorite Lynch 001

NASA Astrophysics Data System (ADS)

Elewa, Nancy N.; Cadogan, J. M.

2017-11-01

The Lynch 001 meteorite was found in the Nullarbor Plain region of Western Australia in 1977. This meteorite is classified as an ordinary chondrite of the petrologic group L5/6 that has undergone `minor to moderate' terrestrial weathering. Here, we characterize the Fe-bearing phases in this chondrite using 57Fe Mössbauer spectroscopy carried out over the temperature range 13 K to room temperature (295 K). The paramagnetic doublets of olivine, pyroxene and a superparamagnetic ferric phase dominate the room temperature Mössbauer spectrum. On the basis of the room temperature quadrupole splitting of the olivine component, we estimate its composition to be Fa 30(5). Besides the paramagnetic ferric component, accounting for ˜15 % of the spectral area at room temperature, magnetically ordered ferric phases were also detected. The total relative proportion of the Fe 3+ components allows us to estimate the terrestrial age of Lynch 001 to be 6,500 ± 1,500 yr, consistent with the value of 6,700 ± 1,300 yr determined by 14C dating.

Comparison of urodynamic volume measurements using room and body temperature saline: a double-blinded randomized crossover study design.

PubMed

Gehrich, Alan Paul; Hill, Micah J; McWilliams, Grant D E; Larsen, Wilma; McCartin, Tamarin

2012-01-01

Urodynamic studies, routinely performed in women with lower urinary tract symptoms, have a large impact on clinical decision making. Unfortunately, these studies are insensitive in reproducing idiopathic detrusor overactivity (IDO). We set out to examine whether serial cystometry with different distending fluid temperatures could better reproduce symptoms. Eighty-six women were enrolled in a double-blinded, randomized, crossover study. Two cystometries were performed in series, starting with either body temperature fluid (BTF) or room temperature fluid (RTF) and then repeating cystometry with the other temperature fluid. Primary outcomes included first sensation, first urge, and maximum cystometric capacity. Secondary outcomes included subjective sensation of bladder discomfort and the incidence of IDO. In aggregate, the temperature of the fluid did not affect volumes of bladder sensation. There were no differences in self-reported bladder irritation or IDO between the different temperature fluids. There was a significant carryover effect with BTF. BTF administered first reached sensory thresholds at lower volumes than when it was administered second after RTF. Room temperature fluid cystometry showed no statistical difference in volume between first fill and second fill. Idiopathic detrusor overactivity contractions were seen in 9% of studies and were not affected by period or temperature. These data suggest that BTF and RTF independently do not affect bladder sensory thresholds. The periodicity in combination with varying fluid temperature is of greater impact. This study documents that changes in temperature of the distending fluid from BTF to RTF or vice versa likely do not provoke IDO contractions.

Preservation of sperm within the mouse cauda epididymidis in salt or sugars at room temperature.

PubMed

Ono, Tetsuo; Mizutani, Eiji; Li, Chong; Wakayama, Teruhiko

2010-08-01

The development of preservation techniques for male gametes at room temperature might allow us to store them in a simple and cost-effective manner. In this study, we studied the use of pure salt or sugar to preserve the whole cauda epididymidis, because it is known that food can be preserved in this way at room temperature for long periods. Mouse epididymides were placed directly in powdered salt (NaCl) or sugars (glucose or raffinose) for 1 day to 1 year at room temperature. Spermatozoa were recovered from the preserved organs after being rehydrated with medium and then isolated sperm heads were microinjected into fresh oocytes. Importantly, the oocyte activation capacity of spermatozoa was maintained after epididymal storage in NaCl for 1 year, whereas most untreated spermatozoa failed to activate oocytes within 1 month of storage. Pronuclear morphology, the rate of extrusion of a second polar body and the methylation status of histone H3 lysine 9 (H3K9me3) in those zygotes were similar to those of zygotes fertilized with fresh spermatozoa. However, the developmental ability of the zygotes decreased within 1 day of sperm storage. This effect led to nuclear fragmentation at the 2-cell embryo stage, irrespective of the storage method used. Thus, although the preserved sperm failed to allow embryo development, their oocyte activation factors were maintained by salt storage of the epididymis for up to 1 year at room temperature.

Refrigeration and cryopreservation of platelets differentially affect platelet metabolism and function: a comparison with conventional platelet storage conditions.

PubMed

Johnson, Lacey; Tan, Shereen; Wood, Ben; Davis, April; Marks, Denese C

2016-07-01

Alternatives to room temperature storage of platelets (PLTs) may be beneficial to extend the limited shelf life and support transfusion logistics in rural and military areas. The aim of this study was to assess the morphologic, metabolic, and functional aspects of PLTs stored at room temperature or in refrigerated conditions or cryopreserved. A three-arm pool-and-split study was carried out using buffy coat-derived PLTs stored in 30% plasma/70% SSP+. The three matched treatment arms were room temperature stored (20-24°C), cold-stored (2-6°C), and cryopreserved (-80°C with dimethyl sulfoxide). Liquid-stored PLTs were tested over a 21-day period, while cryopreserved PLTs were examined immediately after thawing and after 6 and 24 hours of storage at room temperature. Cold-stored and cryopreserved PLTs underwent a significant shape change, although the cryopreserved PLTs appeared to recover from this during subsequent storage. Glycolytic metabolism was reduced in cold-stored PLTs, but accelerated in cryopreserved PLTs, while oxidative phosphorylation was negatively affected by both storage conditions. PLT aggregation was potentiated by cold storage and diminished by cryopreservation in comparison to room temperature-stored PLTs. Cold storage and cryopreservation resulted in faster clot formation (R-time; thromboelastography), which was associated with an increase in microparticles. Cold storage and cryopreservation of PLTs led to morphologic and metabolic changes. However, storage under these conditions appears to maintain or even enhance certain aspects of in vitro PLT function. © 2016 AABB.

Hot flashes, core body temperature, and metabolic parameters in breast cancer survivors.

PubMed

Carpenter, Janet S; Gilchrist, Janet M; Chen, Kong; Gautam, Shiva; Freedman, Robert R

2004-01-01

To examine core body temperature, energy expenditure, and respiratory quotient among breast cancer survivors experiencing hot flashes and compare these data to published studies from healthy women. In an observational study, nine breast cancer survivors with daily hot flashes who met specified criteria spent 24 hours in a temperature- and humidity-controlled whole-room indirect calorimeter (ie, metabolic room). Demographic and disease/treatment information were obtained and the following were measured: hot flashes via sternal skin conductance monitoring (sampled every second); core body temperature via an ingested radiotelemetry pill (sampled every 10 seconds); and energy expenditure and respiratory quotient via a whole-room indirect calorimeter (calculated every minute). Circadian analysis of core temperature indicated wide variability with disrupted circadian rhythm noted in all women. Core temperature began to rise 20 minutes pre-flash to 7 minutes pre-flash (0.09 degrees C increase). Increases in energy expenditure and respiratory quotient increased with each hot flash. Findings are comparable to published data from healthy women and warrant replication in larger, more diverse samples of women treated for breast cancer.

Polymer functionalized nanostructured porous silicon for selective water vapor sensing at room temperature

NASA Astrophysics Data System (ADS)

Dwivedi, Priyanka; Das, Samaresh; Dhanekar, Saakshi

2017-04-01

This paper highlights the surface treatment of porous silicon (PSi) for enhancing the sensitivity of water vapors at room temperature. A simple and low cost technique was used for fabrication and functionalization of PSi. Spin coated polyvinyl alcohol (PVA) was used for functionalizing PSi surface. Morphological and structural studies were conducted to analyze samples using SEM and XRD/Raman spectroscopy respectively. Contact angle measurements were performed for assessing the wettability of the surfaces. PSi and functionalized PSi samples were tested as sensors in presence of different analytes like ethanol, acetone, isopropyl alcohol (IPA) and water vapors in the range of 50-500 ppm. Electrical measurements were taken from parallel aluminium electrodes fabricated on the functionalized surface, using metal mask and thermal evaporation. Functionalized PSi sensors in comparison to non-functionalized sensors depicted selective and enhanced response to water vapor at room temperature. The results portray an efficient and selective water vapor detection at room temperature.

Direct writing of room temperature and zero field skyrmion lattices by a scanning local magnetic field

NASA Astrophysics Data System (ADS)

Zhang, Senfu; Zhang, Junwei; Zhang, Qiang; Barton, Craig; Neu, Volker; Zhao, Yuelei; Hou, Zhipeng; Wen, Yan; Gong, Chen; Kazakova, Olga; Wang, Wenhong; Peng, Yong; Garanin, Dmitry A.; Chudnovsky, Eugene M.; Zhang, Xixiang

2018-03-01

Magnetic skyrmions are topologically protected nanoscale spin textures exhibiting fascinating physical behaviors. Recent observations of room temperature skyrmions in sputtered multilayer films are an important step towards their use in ultra-low power devices. Such practical applications prefer skyrmions to be stable at zero magnetic fields and room temperature. Here, we report the creation of skyrmion lattices in Pt/Co/Ta multilayers by a scanning local field using magnetic force microscopy tips. We also show that those newly created skyrmion lattices are stable at both room temperature and zero fields. Lorentz transmission electron microscopy measurements reveal that the skyrmions in our films are of Néel-type. To gain a deeper understanding of the mechanism behind the creation of a skyrmion lattice by the scanning of local fields, we perform micromagnetic simulations and find the experimental results to be in agreement with our simulation data. This study opens another avenue for the creation of skyrmion lattices in thin films.

Room temperature ferroelectricity in one-dimensional single chain molecular magnets [{M(Δ)M(Λ)}(ox)2(phen)2]n (M = Fe and Mn)

NASA Astrophysics Data System (ADS)

Bhatt, Pramod; Mukadam, M. D.; Meena, S. S.; Mishra, S. K.; Mittal, R.; Sastry, P. U.; Mandal, B. P.; Yusuf, S. M.

2017-03-01

The ferroelectric materials are mainly focused on pure inorganic oxides; however, the organic molecule based materials have recently attracted great attention because of their multifunctional properties. The mixing of oxalate and phenanthroline ligands with metal ions (Fe or Mn) at room temperature followed by hydrothermal treatment results in the formation of one-dimensional single chain molecular magnets which exhibit room temperature dielectric and ferroelectric behavior. The compounds are chiral in nature, and exhibit a ferroelectric behavior, attributed to the polar point group C2, in which they crystallized. The compounds are also associated with a dielectric loss and thus a relaxation process. The observed electric dipole moment, essential for a ferroelectricity, has been understood quantitatively in terms of lattice distortions at two different lattice sites within the crystal structure. The studied single chain molecular magnetic materials with room temperature ferroelectric and dielectric properties could be of great technological importance in non-volatile memory elements, and high-performance insulators.

Study on room temperature gas-sensing performance of CuO film-decorated ordered porous ZnO composite by In2O3 sensitization

PubMed Central

Li, Tian-tian; Bao, Na; Geng, Ai-fang; Yang, Ying; Dong, Xiang-ting

2018-01-01

For the first time, ordered mesoporous ZnO nanoparticles have been synthesized by a template method. The electroplating after chemical plating method was creatively used to form copper film on the surface of the prepared ZnO, and then a CuO film-decorated ordered porous ZnO composite (CuO/ZnO) was obtained by a high-temperature oxidation method. In2O3 was loaded into the prepared CuO film–ZnO by an ultrasonic-assisted method to sensitize the room temperature gas-sensing performance of the prepared CuO/ZnO materials. The doped In2O3 could effectively improve the gas-sensing properties of the prepared materials to nitrogen oxides (NOx) at room temperature. The 1% In2O3 doped CuO/ZnO sample (1 wt% In2O3–CuO/ZnO) showed the best gas-sensing properties whose response to 100 ppm NOx reached 82%, and the detectable minimum concentration reached 1 ppm at room temperature. The prepared materials had a good selectivity, better response, very low detection limit, and high sensitivity to NOx gas at room temperature, which would have a great development space in the gas sensor field and a great research value. PMID:29515887

Self-generated Local Heating Induced Nanojoining for Room Temperature Pressureless Flexible Electronic Packaging

PubMed Central

Peng, Peng; Hu, Anming; Gerlich, Adrian P.; Liu, Yangai; Zhou, Y. Norman

2015-01-01

Metallic bonding at an interface is determined by the application of heat and/or pressure. The means by which these are applied are the most critical for joining nanoscale structures. The present study considers the feasibility of room-temperature pressureless joining of copper wires using water-based silver nanowire paste. A novel mechanism of self-generated local heating within the silver nanowire paste and copper substrate system promotes the joining of silver-to-silver and silver-to-copper without any external energy input. The localized heat energy was delivered in-situ to the interfaces to promote atomic diffusion and metallic bond formation with the bulk component temperature stays near room-temperature. This local heating effect has been detected experimentally and confirmed by calculation. The joints formed at room-temperature without pressure achieve a tensile strength of 5.7 MPa and exhibit ultra-low resistivity in the range of 101.3 nOhm·m. The good conductivity of the joint is attributed to the removal of organic compounds in the paste and metallic bonding of silver-to-copper and silver-to-silver. The water-based silver nanowire paste filler material is successfully applied to various flexible substrates for room temperature bonding. The use of chemically generated local heating may become a potential method for energy in-situ delivery at micro/nanoscale. PMID:25788019

Heated Ultrasound Gel and Patient Satisfaction with Bedside Ultrasound Studies: The HUGS Trial

PubMed Central

Krainin, Benjamin M.; Thaut, Lane C.; April, Michael D.; Curtis, Ryan A.; Kaelin, Andrea L.; Hardy, Garrett B.; Weymouth, Wells L.; Srichandra, Jonathan; Chin, Eric J.; Summers, Shane M.

2017-01-01

Introduction Our goal was to determine if heated gel for emergency department (ED) bedside ultrasonography improves patient satisfaction compared to room-temperature gel. Methods We randomized a convenience sample of ED patients determined by their treating physician to require a bedside ultrasound (US) study to either heated gel (102.0° F) or room-temperature gel (82.3° F). Investigators performed all US examinations. We informed all subjects that the study entailed investigation into various measures to improve patient satisfaction with ED US examinations but did not inform them of our specific focus on gel temperature. Investigators wore heat-resistant gloves while performing the examinations to blind themselves to the gel temperature. After completion of the US, subjects completed a survey including the primary outcome measure of patient satisfaction as measured on a 100-mm visual analogue scale (VAS). A secondary outcome was patient perceptions of sonographer professionalism measured by an ordinal scale (1–5). Results We enrolled 124 subjects; 120 completed all outcome measures. Of these, 59 underwent randomization to US studies with room-temperature gel and 61 underwent randomization to heated US gel. Patient 100-mm VAS satisfaction scores were 83.9 among patients undergoing studies with room-temperature gel versus 87.6 among subjects undergoing studies with heated gel (effect size 3.7, 95% confidence interval −1.3–8.6). There were similarly no differences between the two arms with regard to patient perceptions of sonographer professionalism. Conclusion The use of heated ultrasound gel appears to have no material impact on the satisfaction of ED patients undergoing bedside ultrasound studies. PMID:29085538

UV-light-assisted ethanol sensing characteristics of g-C3N4/ZnO composites at room temperature

NASA Astrophysics Data System (ADS)

Zhai, Jiali; Wang, Tao; Wang, Chuang; Liu, Dechen

2018-05-01

A highly efficient UV-light-assisted room temperature sensor based on g-C3N4/ZnO composites were prepared by an in situ precipitation method. The thermostability, composition, structure, and morphology properties of the as-prepared g-C3N4/ZnO composites were characterized by TGA, XRD, FT-IR, TEM, and XPS, respectively. And then, we studied the ethanol (C2H5OH) sensing performance of the g-C3N4/ZnO composites at the room temperature. Compared with pure ZnO and g-C3N4, the gas sensing activity of g-C3N4/ZnO composites was greatly improved at room temperature, for example, the g-C3N4/ZnO-8% composites showed an obvious response of 121-40 ppm C2H5OH at room temperature, which was 60 times higher than the pure ZnO based on the sensors under the same condition. The great enhancement of the C2H5OH sensing properties of composites can be understood by the efficient separation of photogenerated charge carriers of g-C3N4/ZnO heterogeneous and the UV-light catalytic effect. Finally, a possible mechanism for the gas sensing activity was proposed.

Instantaneous radioiodination of rose bengal at room temperature and a cold-kit therefor. [DOE patent application

DOEpatents

O'Brien, H. Jr.; Hupf, H.B.; Wanek, P.M.

The disclosure relates to the radioiodination of rose bengal at room temperature and a cold-kit therefor. A purified rose bengal tablet is stirred into acidified ethanol at or near room temperature, until a suspension forms. Reductant-free /sup 125/I/sup -/ is added and the resulting mixture stands until the exchange label reaction occurs at room temperature. A solution of sterile isotonic phosphate buffer and sodium hydroxide is added and the final resulting mixture is sterilized by filtration.

Instantaneous radioiodination of rose bengal at room temperature and a cold kit therefor

DOEpatents

O'Brien, Jr., Harold A.; Hupf, Homer B.; Wanek, Philip M.

1981-01-01

The disclosure relates to the radioiodination of rose bengal at room temperature and a cold-kit therefor. A purified rose bengal tablet is stirred into acidified ethanol at or near room temperature, until a suspension forms. Reductant-free .sup.125 I.sup.- is added and the resulting mixture stands until the exchange label reaction occurs at room temperature. A solution of sterile isotonic phosphate buffer and sodium hydroxide is added and the final resulting mixture is sterilized by filtration.

Stability of allopurinol and of five antineoplastics in suspension.

PubMed

Dressman, J B; Poust, R I

1983-04-01

The stability of allopurinol, azathioprine, chlorambucil, melphalan, mercaptopurine, and thioguanine each in an extemporaneously prepared suspension was studied. Tablets of each drug were crushed, mixed with a suspending agent, and brought to a final volume of 10, 15, or 20 ml with a 2:1 mixture of simple syrup and wild cherry syrup. Suspensions were prepared in the following concentrations: allopurinol (20 mg/ml), azathioprine (50 mg/ml), chlorambucil (2 mg/ml), melphalan (2 mg/ml), mercaptopurine (50 mg/ml), and thioguanine (40 mg/ml). Using high-performance liquid chromatography or ultraviolet scans, duplicate assays were performed on each suspension periodically during storage for up to 84 days at ambient room temperature or 5 degrees C. The time required for the suspensions to drop below 90% of labeled strength was used as an indicator of drug stability. Allopurinol and azathioprine were stable for at least 56 days at room temperature and at 5 degrees C. Chlorambucil decomposed rapidly at room temperature but was stable for seven days when stored at 5 degrees C. Melphalan suspensions did not meet the stated criteria for stability even at the time of initial assay. Mercaptopurine and thioguanine were stable for 14 and 84 days, respectively, at room temperature; at 5 degrees C, assay values dropped below those obtained at room temperature. In the suspension formulation tested, allopurinol, azathioprine, mercaptopurine, and thioguanine are stable for at least 14 days at room temperature; chlorambucil suspensions should be refrigerated and discarded after seven days. Melphalan decomposes too rapidly to make this suspension formulation feasible for extemporaneous compounding.

Design of the thermal insulating test system for doors and windows of buildings

NASA Astrophysics Data System (ADS)

Yu, Yan; Qi, Jinqing; Xu, Yunwei; Wu, Hao; Ou, Jinping

2011-04-01

Thermal insulating properties of doors and widows are important parameter to measure the quality of windows and doors. This paper develops the thermal insulating test system of doors and windows for large temperature difference in winter in north of China according to national standards. This system is integrated with temperature measurement subsystem, temperature control subsystem, the heating power measurement subsystem, and heat transfer coefficient calculated subsystem. The temperature measurement subsystem includes temperature sensor which is implemented by sixty-four thermocouple sensors to measure the key positions of cold room and hot room, and the temperature acquisition unit which adopts Agilent 34901A data acquisition card to achieve self-compensation and accurate temperature capture. The temperature control subsystem including temperature controller and compressor system is used to control the temperature between 0 degree to 20 degree for hot room and -20 degree to 0 degree for cold room. The hot room controller uses fuzzy control algorithm to achieve accurate control of temperature and the cold room controller firstly uses compressor to achieve coarse control and then uses more accurate temperature controller unit to obtain constant temperature(-20 degree). The heating power measurement is mainly to get the heat power of hot room heating devices. After above constant temperature environment is constructed, software of the test system is developed. Using software, temperature data and heat power data can be accurately got and then the heat transfer coefficient, representing the thermal insulating properties of doors and widows, is calculated using the standard formula. Experimental results show that the test system is simple, reliable and precise. It meets the testing requirements of national standard and has a good application prospect.

A Fiber Bragg grating based tilt sensor suitable for constant temperature room

NASA Astrophysics Data System (ADS)

Tang, Guoyu; Wei, Jue; Zhou, Wei; Wu, Mingyu; Yang, Meichao; Xie, Ruijun; Xu, Xiaofeng

2015-07-01

Constant-temperature rooms have been widely used in industrial production, quality testing, and research laboratories. This paper proposes a high-precision tilt sensor suitable for a constant- temperature room, which has achieved a wide-range power change while the fiber Bragg grating (FBG) reflection peak wavelength shifted very little, thereby demonstrating a novel method for obtaining a high-precision tilt sensor. This paper also studies the effect of the reflection peak on measurement precision. The proposed sensor can distinguish the direction of tilt with an excellent sensitivity of 403 dBm/° and a highest achievable resolution of 2.481 × 10-5 ° (that is, 0.08% of the measuring range).

Shelf-life of bioprosthetic heart valves: a structural and mechanical study.

PubMed

Julien, M; Létouneau, D R; Marois, Y; Cardou, A; King, M W; Guidoin, R; Chachra, D; Lee, J M

1997-04-01

This study was undertaken to evaluate the influence of storage conditions on the shelf-life of porcine bioprosthetic valves. Fifty-five unimplanted porcine bioprostheses have been evaluated. The valves were stored in 0.5% buffered glutaraldehyde solution for different periods of time (7, 23 and 32 months). Twenty-eight valves were refrigerated while the remaining valves were stored at room temperature. The pH of the glutaraldehyde solution at room temperature decreased with time of storage, while that kept in the refrigerator remained stable over the course of the study. Macroscopic observations showed that the valve tissues kept at room temperature, especially for the periods of 23 and 32 months, became darker and more yellow in colour, whereas the refrigerated specimens exhibited no such changes in appearance. Scanning electron microscopy analysis revealed no noticeable differences on the surfaces of the leaflets stored under different conditions. Mechanical tests, including stress-strain response, stress relaxation and fracture behaviour, were carried out. Analysis of variance showed that the storage temperature, but not the length of storage, had a significant effect on some mechanical properties. The stress relaxation at 1000 s (P = 0.05), the ultimate tensile strength (P = 0.01) and the strain at fracture (P = 0.04) were all higher after storage at room temperature compared to the results after refrigeration. No statistically significant changes in the denaturation temperature of the collagen were observed between the different storage conditions. In conclusion, the storage temperature appears to have some influence on the bioprosthetic tissue. The bioprostheses stored under ambient conditions experience changes which may influence their longterm in vivo performance.

Ordered iron aluminide alloys having an improved room-temperature ductility and method thereof

DOEpatents

Sikka, Vinod K.

1992-01-01

A process is disclosed for improving the room temperature ductility and strength of iron aluminide intermetallic alloys. The process involves thermomechanically working an iron aluminide alloy by means which produce an elongated grain structure. The worked alloy is then heated at a temperature in the range of about 650.degree. C. to about 800.degree. C. to produce a B2-type crystal structure. The alloy is rapidly cooled in a moisture free atmosphere to retain the B2-type crystal structure at room temperature, thus providing an alloy having improved room temperature ductility and strength.

Space environmental effects on graphite-epoxy compressive properties and epoxy tensile properties

NASA Technical Reports Server (NTRS)

Fox, Derek J.; Sykes, George F., Jr.; Herakovich, Carl T.

1987-01-01

This study characterizes the effects of electron radiation and temperature on a graphite-epoxy composite material. Compressive properties of the T300/934 material system were obtained at -250 F (-157 C), room temperature, and 250 F (121 C). Tensile specimens of the Fiberite 934 epoxy resin were fabricated and tested at room temperature and 250 F (121 C). Testing was conducted in the baseline (nonirradiated) and irradiated conditions. The radiation exposure was designed to simulate 30 year, worst-case exposure in geosynchronous Earth orbit. Mechanical properties tended to degrade at elevated temperature and improve at cryogenic temperature. Irradiation generally degraded properties at all temperatures.

Thermal Characterization and Flammability of Structural Epoxy Adhesive and Carbon/Epoxy Composite with Environmental and Chemical Degradation (Postprint)

DTIC Science & Technology

2012-01-01

this study). TGA scans show the thermal degradation of carbon/ epoxy composite by fuel additive at room temperature. Through Microscale Combustion...concerns regarding the durability of structural epoxy adhesive contaminated by hydraulic fluid or fuel additive , under simplified test conditions (no...higher than room tem- perature) or fuel additive (at all temperatures of this study). TGA scans show the thermal degradation of carbon/ epoxy composite

The effect of reaction temperature on the room temperature ferromagnetic property of sol-gel derived tin oxide nanocrystal

NASA Astrophysics Data System (ADS)

Sakthiraj, K.; Hema, M.; Balachandra Kumar, K.

2018-06-01

In the present study, nanocrystalline tin oxide materials were prepared using sol-gel method with different reaction temperatures (25 °C, 50 °C, 75 °C & 90 °C) and the relation between the room temperature ferromagnetic property of the sample with processing temperature has been analysed. The X-ray diffraction pattern and infrared absorption spectra of the as-prepared samples confirm the purity of the samples. Transmission electron microscopy images visualize the particle size variation with respect to reaction temperature. The photoluminescence spectra of the samples demonstrate that luminescence process in materials is originated due to the electron transition mediated by defect centres. The room temperature ferromagnetic property is observed in all the samples with different amount, which was confirmed using vibrating sample magnetometer measurements. The saturation magnetization value of the as-prepared samples is increased with increasing the reaction temperature. From the photoluminescence & magnetic measurements we accomplished that, more amount of surface defects like oxygen vacancy and tin interstitial are created due to the increase in reaction temperature and it controls the ferromagnetic property of the samples.

Wide bandgap BaSnO3 films with room temperature conductivity exceeding 104 S cm−1

PubMed Central

Prakash, Abhinav; Xu, Peng; Faghaninia, Alireza; Shukla, Sudhanshu; Ager, Joel W.; Lo, Cynthia S.; Jalan, Bharat

2017-01-01

Wide bandgap perovskite oxides with high room temperature conductivities and structural compatibility with a diverse family of organic/inorganic perovskite materials are of significant interest as transparent conductors and as active components in power electronics. Such materials must also possess high room temperature mobility to minimize power consumption and to enable high-frequency applications. Here, we report n-type BaSnO3 films grown using hybrid molecular beam epitaxy with room temperature conductivity exceeding 104 S cm−1. Significantly, these films show room temperature mobilities up to 120 cm2 V−1 s−1 even at carrier concentrations above 3 × 1020 cm−3 together with a wide bandgap (3 eV). We examine the mobility-limiting scattering mechanisms by calculating temperature-dependent mobility, and Seebeck coefficient using the Boltzmann transport framework and ab-initio calculations. These results place perovskite oxide semiconductors for the first time on par with the highly successful III–N system, thereby bringing all-transparent, high-power oxide electronics operating at room temperature a step closer to reality. PMID:28474675

Proposal for a room-temperature diamond maser

PubMed Central

Jin, Liang; Pfender, Matthias; Aslam, Nabeel; Neumann, Philipp; Yang, Sen; Wrachtrup, Jörg; Liu, Ren-Bao

2015-01-01

The application of masers is limited by its demanding working conditions (high vacuum or low temperature). A room-temperature solid-state maser is highly desirable, but the lifetimes of emitters (electron spins) in solids at room temperature are usually too short (∼ns) for population inversion. Masing from pentacene spins in p-terphenyl crystals, which have a long spin lifetime (∼0.1 ms), has been demonstrated. This maser, however, operates only in the pulsed mode. Here we propose a room-temperature maser based on nitrogen-vacancy centres in diamond, which features the longest known solid-state spin lifetime (∼5 ms) at room temperature, high optical pumping efficiency (∼106 s−1) and material stability. Our numerical simulation demonstrates that a maser with a coherence time of approximately minutes is feasible under readily accessible conditions (cavity Q-factor ∼5 × 104, diamond size ∼3 × 3 × 0.5 mm3 and pump power <10 W). A room-temperature diamond maser may facilitate a broad range of microwave technologies. PMID:26394758

Wide bandgap BaSnO 3 films with room temperature conductivity exceeding 10 4 S cm -1

DOE PAGES

Prakash, Abhinav; Xu, Peng; Faghaninia, Alireza; ...

2017-05-05

Wide bandgap perovskite oxides with high room temperature conductivities and structural compatibility with a diverse family of organic/inorganic perovskite materials are of sign ificant interest as transparent conductors and as active components in power electronics. Such materials must also possess high room temperature mobility to minimize power consumption and to enable high-frequency applications. Here, we report n-type BaSnO 3 films grown using hybrid molecular beam epitaxy with room temperature conductivity exceeding 10 4 S cm -1 . Significantly, these films show room temperature mobilities up to 120 cm 2 V -1 s -1 even at carrier concentrations abovemore » 3 × 10 20 cm -3 together with a wide bandgap (3 eV). We examine the mobility-limiting scattering mechanisms by calculating temperature-dependent mobility, and Seebeck coefficient using the Boltzmann transport framework and ab-initio calculations. These results place perovskite oxide semiconductors for the first time on par with the highly successful III-N system, thereby bringing all-transparent, high-power oxide electronics operating at room temperature a step closer to reality.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hurtubise, R.J.

Interaction models were developed for moisture effects on room-temperature fluorescence (RTF) and room-temperature phosphorescence (RTP) of compounds adsorbed on filter paper. The models described both dynamic and matrix quenching and also related the Young modulus of filter paper to quenching of phosphor on moist filter paper. Photophysical parameters for lumiphors in solution and on solid matrices were compared. Results showed that for some compounds, solid-matrix luminescence has greater analytical potential than solution luminescence. Also, the solid-matrix systems into one of two categories depending on how the intersystem crossing rate constants change with temperature. The first study was carried out onmore » effects of heavy atom on solid-matrix luminescence. With some heavy atoms, maximum solid-matrix phosphorescence quantum yield was obtained at room temperature, and there was no need to use low temperature to obtain a strong phosphorescence signal. By studying solid-matrix luminescence properties of phosphors adsorbed on sodium acetate and deuterated sodium acetate, an interaction model was developed for p-aminobenzoic acid anion adsorbed on sodium acetate. It was shown that the energy-gap law was applicable to solid-matrix luminescence. Also, deuterated phenanthrene and undeuterated phenanthrene were used to study nonradiative transition of excited triplet state of adsorbed phosphors. Heat capacities of several solid matrices were obtained vs temperature and related to vibrational coupling of solid matrix with phosphor. Photophysical study was performed on the hydrolysis products of benzo(a)pyrene-DNA adducts. Also, an analytical method was developed for tetrols in human lung fractions. Work was initiated on the formation of room temperature glasses with glucose and trehalose. Also, work has begun for the development of an oxygen sensor by measuring the RTP quenching of triphenylene on filter paper.« less

Photophysics of Ru(II)— and Os(II)—polypyridine complexes in poly(ethyleneoxide) matrices

NASA Astrophysics Data System (ADS)

Campagna, Sebastiano; Bartolotta, Antonino; Marco, Gaetano Di

1993-04-01

Photophysical properties of Ru(bpy) 32+, Ru(bpy) 2(biq) 2+, and Os(bpy) 32+ (bpy=2,2'-bipyridine; biq=2,2'-biquinoline) in poly(ethyleneoxide) matrices (PEO) constituted by (CH 2CH 2O) repeating units, with average molecular weight 400 (PEO-400, a highly viscous fluid) and 600000 dalton (PEO-600000, a semicrystalline solid) have been studied at room temperature and 77 K. Comparison with similar systems is made. The absorption spectra, luminescence spectra and lifetimes at room temperature of the three complexes in both matrices are in agreement with the typical features reported for the same complexes in fluid solutions, and indicate that fast excited state relaxation via solvent reorganization occurs in both PEO matrices at room temperature. Such behaviour is not usual for solid matrices and is attributed to the microheterogeneous nature of PEO-600000 and to the ability of the solid PEO amorphous region to stabilize polar species within the timescale of radiative relaxation. The results suggest that PEO-600000 is a promising medium for studying electron and energy transfer processes having mild driving forces in the solid state at room temperature.

Low and room temperature magnetic features of the traffic related urban airborne PM

NASA Astrophysics Data System (ADS)

Winkler, A.; Sagnotti, L.

2012-04-01

We used magnetic measurements and analyses - such as hysteresis loops and FORCs both at room temperature and at 10K, isothermal remanent magnetization (IRM) vs temperature curves (from 10K to 293K) and IRM vs time decay curves - to characterize the magnetic properties of the traffic related airborne particulate matter (PM) in Rome. This study was specifically addressed to the identification of the ultrafine superparamagnetic (SP) particles, which are particularly sensitive to thermal relaxation effects, and on the eventual detection of low temperature phase transitions which may affect various magnetic minerals. We compared the magnetic properties at 10K and at room temperature of Quercus ilex leaves, disk brakes, diesel and gasoline exhaust pipes powders collected from vehicles circulating in Rome. The magnetic properties of the investigated powders significantly change upon cooling, and no clear phase transition occurs, suggesting that the thermal dependence is mainly triggered by the widespread presence of ultrafine SP particles. The contribution of the SP fraction to the total remanence of traffic related PM samples was quantified at room temperature measuring the decay of a IRM 100 s after the application of a saturation magnetic field. This same method has been also tested at 10K to investigate the temperature dependence of the observed time decay.

Irradiation effect of the insulating materials for fusion superconducting magnets at cryogenic temperature

NASA Astrophysics Data System (ADS)

Kobayashi, Koji; Akiyama, Yoko; Nishijima, Shigehiro

2017-09-01

In ITER, superconducting magnets should be used in such severe environment as high fluence of fast neutron, cryogenic temperature and large electromagnetic forces. Insulating material is one of the most sensitive component to radiation. So radiation resistance on mechanical properties at cryogenic temperature are required for insulating material. The purpose of this study is to evaluate irradiation effect of insulating material at cryogenic temperature by gamma-ray irradiation. Firstly, glass fiber reinforced plastic (GFRP) and hybrid composite were prepared. After irradiation at room temperature (RT) or liquid nitrogen temperature (LNT, 77 K), interlaminar shear strength (ILSS) and glass-transition temperature (Tg) measurement were conducted. It was shown that insulating materials irradiated at room temperature were much degraded than those at cryogenic temperature.

Stability of ceftiofur sodium and cefquinome sulphate in intravenous solutions.

PubMed

Dołhań, Agnieszka; Jelińska, Anna; Bębenek, Marcelina

2014-01-01

Stability of ceftiofur sodium and cefquinome sulphate in intravenous solutions was studied. Chromatographic separation and quantitative determination were performed by using a high-performance liquid chromatography with UV-DAD detection. During the stability study, poly(vinylchloride) minibags were filled with a solution containing 5 mg of ceftiofur sodium or cefquinome sulphate and diluted to 0.2 mg/mL with suitable intravenous solution depending on the test conditions. The solutions for the study were protected from light and stored at room temperature (22°C), refrigerated (6°C), frozen (-20°C) for 30 days, and then thawed at room temperature. A comparison of results obtained at 22°C and 6°C for the same intravenous solutions showed that temperature as well as components of solutions and their concentration had an influence on the stability of ceftiofur sodium and cefquinome sulphate. It was found that ceftiofur sodium and cefquinome sulphate dissolved in intravenous solutions used in this study may be stored at room temperature and at 6°C for up to 48 h.

Fabrication method for a room temperature hydrogen sensor

NASA Technical Reports Server (NTRS)

Shukla, Satyajit V. (Inventor); Cho, Hyoung (Inventor); Seal, Sudipta (Inventor); Ludwig, Lawrence (Inventor)

2011-01-01

A sensor for selectively determining the presence and measuring the amount of hydrogen in the vicinity of the sensor. The sensor comprises a MEMS device coated with a nanostructured thin film of indium oxide doped tin oxide with an over layer of nanostructured barium cerate with platinum catalyst nanoparticles. Initial exposure to a UV light source, at room temperature, causes burning of organic residues present on the sensor surface and provides a clean surface for sensing hydrogen at room temperature. A giant room temperature hydrogen sensitivity is observed after making the UV source off. The hydrogen sensor of the invention can be usefully employed for the detection of hydrogen in an environment susceptible to the incursion or generation of hydrogen and may be conveniently used at room temperature.

Characterizing the temperature dependence of electronic packaging-material properties

NASA Astrophysics Data System (ADS)

Fu, Chia-Yu; Ume, Charles

1995-06-01

A computer-controlled, temperature-dependent material characterization system has been developed for thermal deformation analysis in electronic packaging applications, especially for printed wiring assembly warpage study. For fiberglass-reinforced epoxy (FR-4 type) material, the Young's moduli decrease to as low as 20-30% of the room-temperature values, while the shear moduli decrease to as low as 60-70% of the room-temperature values. The electrical resistance strain gage technique was used in this research. The test results produced overestimated values in property measurements, and this was shown in a case study. A noncontact strau]n measurement technique (laser extensometer) is now being used to measure these properties. Discrepancies of finite-element warpage predictions using different property values increase as the temperature increases from the stress-free temperature.

Precipitation hardening behaviour of Al-Mg-Si alloy processed by cryorolling and room temperature rolling

NASA Astrophysics Data System (ADS)

Hussain, Maruff; Nageswara rao, P.; Singh, Dharmendra; Jayaganthan, R.

2018-04-01

The precipitation hardenable aluminium alloy (Al-Mg-Si) plates were solutionized and subjected to rolling at room temperature and liquid nitrogen temperature (RTR, CR) up to a true strain of ∼2.7. The rolled sheets were uniformly aged at room temperature and above room temperature (125 °C) to induce precipitation. The rolled and aged samples were analysed using differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), hardness and tensile tests. The strength and ductility were simultaneously improved after controlled ageing of the cryorolled (CR) and room temperature rolled (RTR) samples. However, the increment in strength is more in RTR material than CR material with same ductility. Transmission electron microscopy analysis revealed the formation of ultrafine grains (UFG) filled with dislocations and nanosized precipitates in the CR and RTR conditions after ageing treatment. The behaviour of CR and RTR alloy is same under natural ageing conditions.

Paramagnetic-to-nonmagnetic transition in antiperovskite nitride Cr3GeN studied by 14N-NMR and µSR

NASA Astrophysics Data System (ADS)

Takao, K.; Liu, Z.; Uji, K.; Waki, T.; Tabata, Y.; Watanabe, I.; Nakamura, H.

2017-06-01

The antiperovskite-related nitride Cr3GeN forms a tetragonal structure with the space group P\\bar{4}{2}1m at room temperature. It shows a tetragonal (P\\bar{4}{2}1m) to tetragonal (I4/mcm) structural transition with a large hysteresis at 300-400 K. The magnetic susceptibility of Cr3GeN shows Curie-Weiss type temperature dependence at high temperature, but is almost temperature-independent below room temperature. We carried out µSR and 14N-NMR microscopy measurements to reveal the magnetic ground state of Cr3GeN. Gradual muon spin relaxation, which is nearly temperature-independent below room temperature, was observed, indicating that Cr3GeN is magnetically inactive. In the 14N-NMR measurement, a quadrupole-split spectrum was obtained at around 14 K = 0. The temperature dependence of 14(1/T1) satisfies the Korringa relation. These experimental results indicate that the ground state of Cr3GeN is Pauli paramagnetic, without antiferromagnetic long-range order.

Room-Temperature Quantum Ballistic Transport in Monolithic Ultrascaled Al-Ge-Al Nanowire Heterostructures.

PubMed

Sistani, Masiar; Staudinger, Philipp; Greil, Johannes; Holzbauer, Martin; Detz, Hermann; Bertagnolli, Emmerich; Lugstein, Alois

2017-08-09

Conductance quantization at room temperature is a key requirement for the utilizing of ballistic transport for, e.g., high-performance, low-power dissipating transistors operating at the upper limit of "on"-state conductance or multivalued logic gates. So far, studying conductance quantization has been restricted to high-mobility materials at ultralow temperatures and requires sophisticated nanostructure formation techniques and precise lithography for contact formation. Utilizing a thermally induced exchange reaction between single-crystalline Ge nanowires and Al pads, we achieved monolithic Al-Ge-Al NW heterostructures with ultrasmall Ge segments contacted by self-aligned quasi one-dimensional crystalline Al leads. By integration in electrostatically modulated back-gated field-effect transistors, we demonstrate the first experimental observation of room temperature quantum ballistic transport in Ge, favorable for integration in complementary metal-oxide-semiconductor platform technology.

Disparities in Ammonia, Temperature, Humidity, and Airborne Particulate Matter between the Micro-and Macroenvironments of Mice in Individually Ventilated Caging

PubMed Central

Rosenbaum, Matthew D; VandeWoude, Susan; Volckens, John; Johnson, Thomas E

2010-01-01

Animal room environmental parameters typically are monitored with the assumption that the environment within the cage closely mirrors the room environment. This study evaluated that premise by examining macro- (room) and microenvironmental (cage) parameters in individually ventilated cages housing mice with variable amounts of bedding over a period of 17 d without cage changes. Intracage ammonia levels remained within recommended human guidelines but were higher than room levels, confirming that microisolation caging is efficient at preventing ammonia generated from animal waste from escaping into the room. Humidity and temperature within cages were consistently higher than room levels. Particles in the room predominantly consisted of fine particles (diameter less than 2.5 µm), presumably from the ambient atmosphere; some of these particles were found in the cage microenvironment. In addition, mouse activity within cages produced larger particles, and these particles contributed to substantially higher aerosol mass concentrations within the cage. These findings demonstrate that, although cage and room environmental parameters differ, knowledge of room environmental conditions can be used to predict certain conditions within the cage. This association is relevant in that typical animal care standard operating procedures rely on room measurements, not intracage measurements, which arguably are more important for assessing animal welfare. Further, location and ambient climate can influence particle concentrations in the room, and consequently within the animal cage, suggesting local weather patterns and air quality may account for variability among studies conducted at sites that are geographically divergent. PMID:20353692

Heat exchange studies on coconut oil cells as thermal energy storage for room thermal conditioning

NASA Astrophysics Data System (ADS)

Sutjahja, I. M.; Putri, Widya A.; Fahmi, Z.; Wonorahardjo, S.; Kurnia, D.

2017-07-01

As reported by many thermal environment experts, room air conditioning might be controlled by thermal mass system. In this paper we discuss the performance of coconut oil cells as room thermal energy storage. The heat exchange mechanism of coconut oil (CO) which is one of potential organic Phase Change Material (PCM) is studied based on the results of temperature measurements in the perimeter and core parts of cells. We found that the heat exchange performance, i.e. heat absorption and heat release processes of CO cells are dominated by heat conduction in the sensible solid from the higher temperature perimeter part to the lower temperature core part and heat convection during the solid-liquid phase transition and sensible liquid phase. The capability of heat absorption as measured by the reduction of air temperature is not influenced by CO cell size. Besides that, the application of CO as the thermal mass has to be accompanied by air circulation to get the cool sensation of the room’s occupants.

Near-room-temperature Mid-infrared Photoconductor Signal and Noise Characterization

DTIC Science & Technology

2012-09-01

Near-room-temperature Mid-infrared Photoconductor Signal and Noise Characterization by Justin R. Bickford, Neal K. Bambha, and Wayne H. Chang...Adelphi, MD 20783-1197 ARL-TR-6169 September 2012 Near-room-temperature Mid-infrared Photoconductor Signal and Noise Characterization...temperature Mid-infrared Photoconductor Signal and Noise Characterization 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6

Stability of acetylcysteine solution repackaged in oral syringes and associated cost savings.

PubMed

Kiser, Tyree H; Oldland, Alan R; Fish, Douglas N

2007-04-01

The physical and chemical stability of repackaged acetylcysteine 600 mg/3 mL solution in oral syringes stored under refrigeration or at room temperature was studied for six months; a cost analysis was also conducted. Acetylcysteine 20% solution for inhalation was repackaged undiluted as 600 mg/3 mL in capped oral syringes and stored either under refrigeration or at room temperature exposed to fluorescent light. Four samples for each storage condition were analyzed in duplicate on day zero, weekly for the first month, and then every two weeks during months 2-6. Physical stability was assessed, and the chemical stability of acetylcysteine was evaluated by high-performance liquid chromatography. Acetylcysteine solution in syringes was physically stable during the entire six-month study period. When stored at room temperature, acetylcysteine retained 99% of the original concentration at three months and 95% at six months after preparation of the syringes. Loss of acetylcysteine was <2% at six months when stored under refrigeration. Packaging acetylcysteine in batches of 100 syringes instead of preparing individual syringes reduced wastage to zero syringes, saving an estimated $247 in drug costs. The estimated pharmacy time savings was 30 hours ($702). Acetylcysteine 20% solution repackaged as 600 mg/3 mL in oral syringes is both physically and chemically stable under refrigeration or at room temperature under normal fluorescent lighting for six months. The total loss of acetylcysteine was approximately 5% at room temperature under fluorescent lighting and <2% under refrigeration. Repackaging the solution in syringes in bulk rather than in single doses demonstrated a measurable cost saving.

Use of Recirculating Ventilation with Dust Filtration to Improve Wintertime Air Quality in a Swine Farrowing Room

PubMed Central

Anthony, T. Renée; Altmaier, Ralph; Jones, Samuel; Gassman, Rich; Park, Jae Hong; Peters, Thomas M.

2016-01-01

The performance of a recirculating ventilation system with dust filtration was evaluated to determine its effectiveness to improve the air quality in a swine farrowing room of a concentrated animal feeding operation (CAFO). Air was exhausted from the room (0.47 m3sec−1; 1000 cfm), treated with a filtration unit (Shaker-Dust Collector), and returned to the farrowing room to reduce dust concentrations while retaining heat necessary for livestock health. The air quality in the room was assessed over a winter, during which time limited fresh air is traditionally brought into the building. Over the study period, dust concentrations ranged from 0.005 to 0.31 mg m−3 (respirable) and 0.17 to 2.09 mg m−3 (inhalable). In-room dust concentrations were reduced (41% for respirable and 33% for inhalable) with the system in operation, while gas concentrations (ammonia [NH3], hydrogen sulfide [H2S], carbon monoxide [CO], carbon dioxide [CO2]) were unchanged. The position of the exhaust and return air systems provided reasonably uniform contaminant distributions, although the respirable dust concentrations nearest one of the exhaust ducts was statistically higher than other locations in the room, with differences averaging only 0.05 mg m−3. Throughout the study, CO2 concentrations consistently exceeded 1540 ppm (industry recommendations) and on eight of the 18 study days it exceeded 2500 ppm (50% of the ACGIH TLV), with significantly higher concentrations near a door to a temperature-controlled hallway that was typically often left open. Alternative heaters are recommended to reduce CO2 concentrations in the room. Contaminant concentrations were modeled using production and environmental factors, with NH3 related to the number of sow in the room and outdoor temperatures and CO2 related to the number of piglets and outdoor temperatures. The recirculating ventilation system provided dust reduction without increasing concentrations of hazardous gases. PMID:25950713

The effect of procedure room temperature and humidity on LASIK outcomes.

PubMed

Seider, Michael I; McLeod, Stephen D; Porco, Travis C; Schallhorn, Steven C

2013-11-01

To determine whether procedure room temperature or humidity during LASIK affect refractive outcomes in a large patient sample. Retrospective cohort study. A total of 202 394 eyes of 105 712 patients aged 18 to 75 years who underwent LASIK at an Optical Express, Inc., location in their United Kingdom and Ireland centers from January 1, 2008, to June 30, 2011, who met inclusion criteria. Patient age, gender, flap creation technique, pre- and 1-month post-LASIK manifest refraction, and ambient temperature and humidity during LASIK were recorded. Effect size determination and univariate and multivariate analyses were performed to characterize the relationships between LASIK procedure room temperature and humidity and postoperative refractive outcome. One month post-LASIK manifest refraction. No clinically significant effect of procedure room temperature or humidity was found on LASIK refractive outcomes. When considering all eyes in our population, an increase of 1°C during LASIK was associated with a 0.003 diopter (D) more hyperopic refraction 1 month postoperatively, and an increase in 1% humidity was associated with a 0.0004 more myopic refraction. These effect sizes were the same or similar when considering only myopic eyes, only hyperopic eyes, and subgroups of eyes stratified by age and preoperative refractive error. Neither procedure room temperature nor humidity during LASIK were found to have a clinically significant relationship with postoperative manifest refraction in our population. Copyright © 2013 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

The effect of procedure room temperature and humidity on LASIK outcomes

PubMed Central

Seider, Michael I.; McLeod, Stephen D.; Porco, Travis C.; Schallhorn, Steven C.

2013-01-01

Objective To determine if procedure room temperature and humidity during LASIK affects refractive outcomes in a very large patient sample. Design Retrospective cohort study. Participants 202,394 eyes of 105,712 patients aged 18 to 75 years old who underwent LASIK at an Optical Express, Inc. location in their United Kingdom and Ireland centers from January 1, 2008 to June 30, 2011 who met inclusion criteria. Methods Patient age, gender, pre- and one month post-LASIK manifest refraction and flap creation technique were recorded as well as the ambient temperature and humidity during LASIK. Effect size determination, in addition to univariate and multivariate analysis was performed to characterize the relationships between LASIK procedure room temperature and humidity and post-operative refractive outcome. Main Outcome Measures One month post-LASIK manifest refraction. Results No clinically significant effect of procedure room temperature or humidity was found on LASIK refractive outcomes. When considering all eyes in our population, an increase of one degree Celsius during LASIK was associated with a 0.003 diopter more hyperopic refraction one month post-operatively and an increase in one percent humidity was associated with a 0.0004 more myopic refraction. These effect sizes were the same or similar when considering only myopic eyes, only hyperopic eyes and subgroups of eyes stratified by age and pre-operative refractive error. Conclusions Procedure room temperature or humidity during LASIK was found to have no clinically significant relationship with post-operative manifest refraction in our population. PMID:23769199

Computationally designed and experimentally confirmed diastereoselective rhodium-catalyzed Pauson-Khand reaction at room temperature.

PubMed

Baik, Mu-Hyun; Mazumder, Shivnath; Ricci, Paolo; Sawyer, James R; Song, Ye-Geun; Wang, Huijun; Evans, P Andrew

2011-05-25

The computational analysis of the rhodium-catalyzed Pauson-Khand reaction indicates that the key transition state is highly charge-polarized, wherein different diastereoisomers have distinctively different charge polarization patterns. Experimental studies demonstrate that chloro-enynes provide the optimal σ-electron-withdrawing group to promote polarization and thereby reduce the activation barrier to provide a highly diastereoselective reaction at room temperature.

Effect of buffer and antioxidant on stability of a mercaptopurine suspension.

PubMed

Aliabadi, Hamidreza Montazeri; Romanick, Marcel; Desai, Sunil; Lavasanifar, Afsaneh

2008-03-01

The stability of standard and modified mercaptopurine suspensions when stored at room temperature and under refrigerated conditions to test the feasibility of increasing shelf life was studied. A 50-mg/mL mercaptopurine suspension was compounded by adding simple syrup, cherry syrup, and sterile water for irrigation to triturated mercaptopurine tablets for the initial reference formulation. Three additional formulations were prepared by adding an antioxidant (ascorbic acid 10 mg), a buffer (sodium phosphate monobasic monohydrate 500 mg), and a combination of antioxidant and buffer to the reference formulation. Each compounded batch was divided into two parts and stored in amber bottles at room temperature (19-23 degrees C) or under refrigerated conditions (4-8 degrees C). Analysis through high-performance liquid chromatography determined mercaptopurine levels after three and seven days and weekly thereafter for at least two weeks after shelf life was reached under specified storage conditions. Solutions with at least 93% of the original mercaptopurine concentration and with no observable sign of aggregation or cake formation were considered stable. The reference suspension of mercaptopurine showed an acceptable physical and chemical stability of up to 5 weeks when stored at room temperature. The addition of ascorbic acid extended the shelf life of the compounded suspension to 11 weeks. However, the addition of sodium phosphate monobasic did not improve the stability of mercaptopurine in the suspension. The results showed a higher stability for all formulations after storage at room temperature compared with those stored in a refrigerator. A standard oral suspension of mercaptopurine contained an acceptable drug concentration for up to 5 weeks when stored at room temperature. The addition of ascorbic acid at a concentration of 0.1% w/v to the standard formulation increased the suspension's shelf life at room temperature to 11 weeks.

Certification of NIST Room Temperature Low-Energy and High-Energy Charpy Verification Specimens

PubMed Central

Lucon, Enrico; McCowan, Chris N.; Santoyo, Ray L.

2015-01-01

The possibility for NIST to certify Charpy reference specimens for testing at room temperature (21 °C ± 1 °C) instead of −40 °C was investigated by performing 130 room-temperature tests from five low-energy and four high-energy lots of steel on the three master Charpy machines located in Boulder, CO. The statistical analyses performed show that in most cases the variability of results (i.e., the experimental scatter) is reduced when testing at room temperature. For eight out of the nine lots considered, the observed variability was lower at 21 °C than at −40 °C. The results of this study will allow NIST to satisfy requests for room-temperature Charpy verification specimens that have been received from customers for several years: testing at 21 °C removes from the verification process the operator’s skill in transferring the specimen in a timely fashion from the cooling bath to the impact position, and puts the focus back on the machine performance. For NIST, it also reduces the time and cost for certifying new verification lots. For one of the low-energy lots tested with a C-shaped hammer, we experienced two specimens jamming, which yielded unusually high values of absorbed energy. For both specimens, the signs of jamming were clearly visible. For all the low-energy lots investigated, jamming is slightly more likely to occur at 21 °C than at −40 °C, since at room temperature low-energy samples tend to remain in the test area after impact rather than exiting in the opposite direction of the pendulum swing. In the evaluation of a verification set, any jammed specimen should be removed from the analyses. PMID:26958453

Certification of NIST Room Temperature Low-Energy and High-Energy Charpy Verification Specimens.

PubMed

Lucon, Enrico; McCowan, Chris N; Santoyo, Ray L

2015-01-01

The possibility for NIST to certify Charpy reference specimens for testing at room temperature (21 °C ± 1 °C) instead of -40 °C was investigated by performing 130 room-temperature tests from five low-energy and four high-energy lots of steel on the three master Charpy machines located in Boulder, CO. The statistical analyses performed show that in most cases the variability of results (i.e., the experimental scatter) is reduced when testing at room temperature. For eight out of the nine lots considered, the observed variability was lower at 21 °C than at -40 °C. The results of this study will allow NIST to satisfy requests for room-temperature Charpy verification specimens that have been received from customers for several years: testing at 21 °C removes from the verification process the operator's skill in transferring the specimen in a timely fashion from the cooling bath to the impact position, and puts the focus back on the machine performance. For NIST, it also reduces the time and cost for certifying new verification lots. For one of the low-energy lots tested with a C-shaped hammer, we experienced two specimens jamming, which yielded unusually high values of absorbed energy. For both specimens, the signs of jamming were clearly visible. For all the low-energy lots investigated, jamming is slightly more likely to occur at 21 °C than at -40 °C, since at room temperature low-energy samples tend to remain in the test area after impact rather than exiting in the opposite direction of the pendulum swing. In the evaluation of a verification set, any jammed specimen should be removed from the analyses.

Inelastic deformation of metal matrix composites: Plasticity and damage mechanisms, part 2

NASA Technical Reports Server (NTRS)

Majumdar, B. S.; Newaz, G. M.

1992-01-01

The inelastic deformation mechanisms for the SiC (SCS-6)/Ti-15-3 system were studied at 538 C (1000 F) using a combination of mechanical measurements and detailed microstructural examinations. The objectives were to evaluate the contributions of plasticity and damage to the overall MMC response, and to compare the room temperature and elevated temperature deformation behaviors. Four different laminates were studied: (0)8, (90)8,(+ or -45)2s, and (0/90)2s, with the primary emphasis on the unidirectional (0)8, and (90)8 systems. The elevated temperature responses were similar to those at room temperature, involving a two-stage elastic-plastic type of response for the (0)8 system, and a characteristic three-stage deformation response for the (90)8 and (+ or -45)2s systems. The primary effects of elevated temperatures included: (1) reduction in the 'yield' and failure strengths; (2) plasticity through diffused slip rather than concentrated planar slip (which occurred at room temperature); and (3) time-dependent deformation. The inelastic deformation mechanism for the (0)8 MMC was dominated by plasticity at both temperatures. For the (90)8 and (+ or -45)2s MMCs, a combination of damage and plasticity contributed to the deformation at both temperatures.

Impact of hot temperature on end-face geometry of LC/UPC connectors

NASA Astrophysics Data System (ADS)

Thongdaeng, Rutsuda; Worasucheepb, Duangrudee; Wangsan, Sathit; Chaichok, Wansan

2014-09-01

The fiber withdrawal of Group 4 (mated-thermal cycle) was observed up to 100 nm as in previous work1. We predict that this withdrawal is mainly caused by the impact of hot temperature (at 75ºC) based on GR-3262 thermal cycle test profile repeated 21 cycles over 7 days; and thus, it was studies here for the purpose of reducing test time. All connectors were separated into four groups: 1) unmated-stored at room temperature, 2) mated-stored at room temperature, 3) unmated-stored at hot temperature, and 4) mated-stored at hot temperature. The hot temperature test was performed on Groups 3 and 4 for 1 hour, while Groups 1 and 2 was left at room temperature. The sample size of each group is 28 LC/UPC connectors. Radius of curvature, fiber height and apex offset were measured before and after that 1 hour. The fiber withdrawal up to 100 nm is found in Group 4 (mated-hot temperature), but no changes are observed in Groups 1-3. These results confirm the impact of hot temperature on fiber height, same as the thermal cycle test in previous work1. Afterward, Group 1-4 were unmated at room temperature for 1 day, 1 week, and 1 month. No significant change in fiber height is found. On the contrary, when Group 1-4 were re-tested as being mated at hot temperature for 1 hour, the fiber withdrawal up to 100 nm is now found in Group 1-3. However, the additional withdrawal up to 50 nm is still observed in Group 4.

Effect of ambient temperature on human pain and temperature perception.

PubMed

Strigo, I A; Carli, F; Bushnell, M C

2000-03-01

Animal studies show reduced nociceptive responses to noxious heat stimuli and increases in endogenous beta-endorphin levels in cold environments, suggesting that human pain perception may be dependent on ambient temperature. However, studies of changes in local skin temperature on human pain perception have yielded variable results. This study examines the effect of both warm and cool ambient temperature on the perception of noxious and innocuous mechanical and thermal stimuli. Ten subjects (7 men and 3 women, aged 20-23 yr) used visual analog scales to rate the stimulus intensity, pain intensity, and unpleasantness of thermal (0-50 degrees C) and mechanical (1.2-28.9 g) stimuli applied on the volar forearm with a 1-cm2 contact thermode and von Frey filaments, respectively. Mean skin temperatures were measured throughout the experiment by infrared pyrometer. Each subject was tested in ambient temperatures of 15 degrees C (cool), 25 degrees C (neutral), and 35 degrees C (warm) on separate days, after a 30-min acclimation to the environment. Studies began in the morning after an 8-h fast. Mean skin temperature was altered by ambient temperature (cool room: 30.1 degrees C; neutral room: 33.4 degrees C; warm room: 34.5 degrees C; P < 0.0001). Ambient temperature affected both heat (44-50 degrees C) and cold (25-0 degrees C) perception (P < 0.01). Stimulus intensity ratings tended to be lower in the cool than in the neutral environment (P < 0.07) but were not different between the neutral and warm environments. Unpleasantness ratings revealed that cold stimuli were more unpleasant than hot stimuli in the cool room and that noxious heat stimuli were more unpleasant in a warm environment. Environmental temperature did not alter ratings of warm (37 and 40 degrees C) or mechanical stimuli. These results indicate that, in humans, a decrease in skin temperature following exposure to cool environments reduces thermal pain. Suppression of Adelta primary afferent cold fiber activity has been shown to increase cold pain produced by skin cooling. Our current findings may represent the reverse phenomenon, i.e., a reduction in thermal nociceptive transmission by the activation of Adelta cutaneous cold fibers.

Pt/ZnO nanoarray nanogenerator as self-powered active gas sensor with linear ethanol sensing at room temperature.

PubMed

Zhao, Yayu; Lai, Xuan; Deng, Ping; Nie, Yuxin; Zhang, Yan; Xing, Lili; Xue, Xinyu

2014-03-21

A self-powered gas sensor that can actively detect ethanol at room temperature has been realized from a Pt/ZnO nanoarray nanogenerator. Pt nanoparticles are uniformly distributed on the whole surface of ZnO nanowires. The piezoelectric output of Pt/ZnO nanoarrays can act not only as a power source, but also as a response signal to ethanol at room temperature. Upon exposure to dry air and 1500 ppm ethanol at room temperature, the piezoelectric output of the device under the same compressive strain is 0.672 and 0.419 V, respectively. Moreover, a linear dependence of the sensitivity on the ethanol concentration is observed. Such a linear ethanol sensing at room temperature can be attributed to the atmosphere-dependent variety of the screen effect on the piezoelectric output of ZnO nanowires, the catalytic properties of Pt nanoparticles, and the Schottky barriers at Pt/ZnO interfaces. The present results can stimulate research in the direction of designing new material systems for self-powered room-temperature gas sensing.

The Effect of Curing Temperature on the Properties of Cement Pastes Modified with TiO2 Nanoparticles

PubMed Central

Pimenta Teixeira, Karine; Perdigão Rocha, Isadora; De Sá Carneiro, Leticia; Flores, Jessica; Dauer, Edward A.; Ghahremaninezhad, Ali

2016-01-01

This paper investigates the effect of curing temperature on the hydration, microstructure, compressive strength, and transport of cement pastes modified with TiO2 nanoparticles. These characteristics of cement pastes were studied using non-evaporable water content measurement, X-ray diffraction (XRD), compressive strength test, electrical resistivity and porosity measurements, and scanning electron microscopy (SEM). It was shown that temperature enhanced the early hydration. The cement pastes cured at elevated temperatures generally showed an increase in compressive strength at an early age compared to the cement paste cured at room temperature, but the strength gain decreased at later ages. The electrical resistivity of the cement pastes cured at elevated temperatures was found to decrease more noticeably at late ages compared to that of the room temperature cured cement paste. SEM examination indicated that hydration product was more uniformly distributed in the microstructure of the cement paste cured at room temperature compared to the cement pastes cured at elevated temperatures. It was observed that high temperature curing decreased the compressive strength and electrical resistivity of the cement pastes at late ages in a more pronounced manner when higher levels of TiO2 nanoparticles were added. PMID:28774073

Response of a Zn₂TiO₄ Gas Sensor to Propanol at Room Temperature.

PubMed

Gaidan, Ibrahim; Brabazon, Dermot; Ahad, Inam Ul

2017-08-31

In this study, three different compositions of ZnO and TiO₂ powders were cold compressed and then heated at 1250 °C for five hours. The samples were ground to powder form. The powders were mixed with 5 wt % of polyvinyl butyral (PVB) as binder and 1.5 wt % carbon black and ethylene-glyco-lmono-butyl-ether as a solvent to form screen-printed pastes. The prepared pastes were screen printed on the top of alumina substrates containing arrays of three copper electrodes. The three fabricated sensors were tested to detect propanol at room temperature at two different concentration ranges. The first concentration range was from 500 to 3000 ppm while the second concentration range was from 2500 to 5000 ppm, with testing taking place in steps of 500 ppm. The response of the sensors was found to increase monotonically in response to the increment in the propanol concentration. The surface morphology and chemical composition of the prepared samples were characterized by Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). The sensors displayed good sensitivity to propanol vapors at room temperature. Operation under room-temperature conditions make these sensors novel, as other metal oxide sensors operate only at high temperature.

Heat treatment versus properties studies associated with the Inconel 718 PBF acoustic filters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smolik, G.R.; Reuter, W.G.

PBF acoustic filter Unit No. 1 cracked when heat treatment was attempted. The effects of prior thermal cycling, solution anneal temperature, and cooling rate from solution anneals were investigated. The investigations concerned influences of the above variables upon both 1400$sup 0$F stress rupture solution- annealed properties and room temperature age-hardened properties. 1400$sup 0$F stress rupture properties were of interest to assist the prevention of cracking during heat treatments. Room temperature age-hardened properties were needed to ensure that design requirement would be provided. Prior thermal cycling was investigated to determine if extra thermal cycles would be detrimental to the repaired filter.more » Slow furnace cools were considered as a means of reducing thermal stresses. Effects of solution annealing at 2000 and 1900$sup 0$F were also determined. Test results showed that slow cooling rates would not only reduce thermal stresses but also improve 1400$sup 0$F ductility. A modified aging treatment was established which provided the required 145 ksi room temperature yield strength for the slowly cooled material. Prior cooling did not degrade final age-hardened room temperature tensile or impact properties. (auth)« less

Magneto-optical Kerr effect of a Ni2.00Mn1.16Ga0.84 single crystal across austenite and intermartensite transitions

NASA Astrophysics Data System (ADS)

Fikáček, Jan; Heczko, Oleg; Kopecký, Vít; Kaštil, Jiří; Honolka, Jan

2018-04-01

We carried out magneto-optical Kerr effect (MOKE) and magnetization measurements on a single crystal of Ni2.00Mn1.16Ga0.84, which is a magnetic shape memory material with application potential for actuator devices or for energy recuperation. Up to the time of our study, there had been reports of MOKE measurements in polar geometry. Against earlier predictions, we show that surface magnetic states of the martensite and the austenite can be also probed efficiently via longitudinal MOKE. A single-variant magnetic state prepared at room temperature is characterized by square-shaped ferromagnetic hysteresis loops yielding coercive fields, which are key material properties for future applications. Temperature dependencies of Kerr rotation were found to be linearly proportional to magnetization for martensitic phases. After passing through an inter-martensitic structural transition below room temperature in zero magnetic field, the coercive fields are more than doubled in comparison with the room temperature values. Above room temperature where an austenite structure is formed, MOKE signals are dominated by quadratic contributions and the magnitude of Kerr rotation drops due to changes in the electronic and magnetic domains structure.

Preliminary Appraisal of Ferrocene as an Igniting Agent for JP-4 Fuel and Fuming Nitric Acid

NASA Technical Reports Server (NTRS)

Miller, RIley O.

1953-01-01

A preliminary experimental study was made of the properties of ferrocene as a solute and as a suspension in JP-4 fuel, and of the ignition delays of ferrocene - JP-4 mixture with A.F. specification 14104 white fuming nitric acid (WFNA). The investigation covered concentrations of 4 to 10 percent by weight ferrocene, and a temperature range of -40 to 80 F. The solubility of ferrocene in JP-4 is about 5 percent at room temperature and about 1 percent (extrapolated) at -80 F. The solubility is increased somewhat by increased aromatics content. Undissolved ferrocene particles of 100 mesh and smaller settle rapidly in JP-4. Clear solutions of 4 and 5 percent ferrocene in JP-4 fuels containing 10 and 25 percent by volume aromatics, respectively, do not ignite with WFNA at room temperature. Mixtures containing 10 percent ferrocene (100- mesh and smaller undissolved particles in suspension) ignited with vigorous persistent flames at room temperature, but did not ignite at -38 F. The ignition delays at room temperature, however, were widely varied; the range from 85 milliseconds to over 1 second perhaps reflected differences in degree of sedimentation.

Thermoelectric Properties of High-Doped Silicon from Room Temperature to 900 K

NASA Astrophysics Data System (ADS)

Stranz, A.; Kähler, J.; Waag, A.; Peiner, E.

2013-07-01

Silicon is investigated as a low-cost, Earth-abundant thermoelectric material for high-temperature applications up to 900 K. For the calculation of module design the Seebeck coefficient and the electrical as well as thermal properties of silicon in the high-temperature range are of great importance. In this study, we evaluate the thermoelectric properties of low-, medium-, and high-doped silicon from room temperature to 900 K. In so doing, the Seebeck coefficient, the electrical and thermal conductivities, as well as the resulting figure of merit ZT of silicon are determined.

Magnetic Properties of Fe-49Co-2V Alloy and Pure Fe at Room and Elevated Temperatures

NASA Technical Reports Server (NTRS)

De Groh, Henry C., III; Geng, Steven M.; Niedra, Janis M.; Hofer, Richard R.

2018-01-01

The National Aeronautics and Space Administration (NASA) has a need for soft magnetic materials for fission power and ion propulsion systems. In this work the magnetic properties of the soft magnetic materials Hiperco 50 (Fe-49wt%Cr-2V) and CMI-C (commercially pure magnetic iron) were examined at various temperatures up to 600 C. Toroidal Hiperco 50 samples were made from stacks of 0.35 mm thick sheet, toroidal CMI-C specimens were machined out of solid bar stock, and both were heat treated prior to testing. The magnetic properties of a Hiperco 50 sample were measured at various temperatures up to 600 C and then again after returning to room temperature; the magnetic properties of CMI-C were tested at temperatures up to 400 C. For Hiperco 50 coercivity decreased as temperature increased, and remained low upon returning to room temperature; maximum permeability improved (increased) with increasing temperature and was dramatically improved upon returning to room temperature; remanence was not significantly affected by temperature; flux density at H = 0.1 kA/m increased slightly with increasing temperature, and was about 20% higher upon returning to room temperature; flux density at H = 0.5 kA/m was insensitive to temperature. It appears that the properties of Hiperco 50 improved with increasing temperature due to grain growth. There was no significant magnetic property difference between annealed and aged CMI-C iron material; permeability tended to decrease with increasing temperature; the approximate decline in the permeability at 400 C compared to room temperature was 30%; saturation flux density, B(sub S), was approximately equal for all temperatures below 400 C; B(sub S) was lower at 400 C.

Stability of echogenic liposomes as a blood pool ultrasound contrast agent in a physiologic flow phantom

PubMed Central

Radhakrishnan, Kirthi; Haworth, Kevin J.; Huang, Shao-Ling; Klegerman, Melvin E.; McPherson, David D.; Holland, Christy K.

2016-01-01

Echogenic liposomes (ELIP) are multifunctional ultrasound contrast agents (UCAs) with a lipid shell encapsulating both air and an aqueous core. ELIP are being developed for molecular imaging and image-guided therapeutic delivery. Stability of the echogenicity of ELIP in physiologic conditions is crucial to their successful translation to clinical use. In this study we determined the effects of the surrounding media’s dissolved air concentration, temperature transition and hydrodynamic pressure on the echogenicity of a chemically modified formulation of ELIP to promote stability and echogenicity. ELIP samples were diluted in porcine plasma or whole blood and pumped through a pulsatile flow system with adjustable hydrodynamic pressures and temperature. B-mode images were acquired using a clinical diagnostic scanner every 5 s for a total duration of 75 s. Echogenicity in porcine plasma was assessed as a function of total dissolved gas saturation. ELIP were added to plasma at room temperature (22 °C) or body temperature (37 °C) and pumped through a system maintained at 22 °C or 37 °C to study the effect of temperature transitions on ELIP echogenicity. Echogenicity at normotensive (120/80 mmHg) and hypertensive pressures (145/90 mmHg) was measured. ELIP were echogenic in plasma and whole blood at body temperature under normotensive to hypertensive pressures. Warming of samples from room temperature to body temperature did not alter echogenicity. However, in plasma cooled rapidly from body temperature to room temperature or in degassed plasma, ELIP lost echogenicity within 20 s at 120/80 mmHg. The stability of echogenicity of a modified ELIP formulation was determined in vitro at body temperature, physiologic gas concentration and throughout the physiologic pressure range. However, proper care should be taken to ensure that ELIP are not cooled rapidly from body temperature to room temperature as they will lose their acoustic properties. Further in vivo investigations will be needed to evaluate the optimal usage of ELIP as blood pool contrast agents. PMID:22929652

Complex temperature dependence of coupling and dissipation of cavity magnon polaritons from millikelvin to room temperature

NASA Astrophysics Data System (ADS)

Boventer, Isabella; Pfirrmann, Marco; Krause, Julius; Schön, Yannick; Kläui, Mathias; Weides, Martin

2018-05-01

Hybridized magnonic-photonic systems are key components for future information processing technologies such as storage, manipulation, or conversion of data both in the classical (mostly at room temperature) and quantum (cryogenic) regime. In this work, we investigate a yttrium-iron-garnet sphere coupled strongly to a microwave cavity over the full temperature range from 290 K to 30 mK . The cavity-magnon polaritons are studied from the classical to the quantum regimes where the thermal energy is less than one resonant microwave quanta, i.e., at temperatures below 1 K . We compare the temperature dependence of the coupling strength geff(T ) , describing the strength of coherent energy exchange between spin ensemble and cavity photon, to the temperature behavior of the saturation magnetization evolution Ms(T ) and find strong deviations at low temperatures. The temperature dependence of magnonic disspation is governed at intermediate temperatures by rare-earth impurity scattering leading to a strong peak at 40 K . The linewidth κm decreases to 1.2 MHz at 30 mK , making this system suitable as a building block for quantum electrodynamics experiments. We achieve an electromagnonic cooperativity in excess of 20 over the entire temperature range, with values beyond 100 in the millikelvin regime as well as at room temperature. With our measurements, spectroscopy on strongly coupled magnon-photon systems is demonstrated as versatile tool for spin material studies over large temperature ranges. Key parameters are provided in a single measurement, thus simplifying investigations significantly.

Structural and electrical characteristics of Bi2YTiVO9 ceramic

NASA Astrophysics Data System (ADS)

Gupta, Prabhasini; Padhee, Rajib; Mahapatra, P. K.; Choudhary, R. N. P.

2018-04-01

Studies of structural and electrical characteristics of a member of the Aurivillius structural family (Bi2YTiVO9), prepared by a standard ceramics technology, have been carried out. The phase-pure compound is found to crystallize in the orthorhombic crystal system. The dielectric constant remains around 200 in the studied frequency range of (1 kHz to 1 MHz) and in a temperature range from room temperature to 200 °C. The loss tangent remains in the range of 0.0236 to 0.0056 at room temperature and 0.081 to 0.009 at 200 °C in the same frequency range. The room temperature hysteresis loop exhibits the ferroelectric nature of the sample with remnant polarization of 0.025 μC/cm2 at the coercive field of 4.880 kV cm‑1. The experimental data obtained from Cole-Cole plot on static as well as infinitely high-frequency permittivity, relaxation time and relaxation distribution parameters are used to simulate ε‧, ε″and tanδ which match nicely with experimental data. The conductivity can be explained on the basis of Correlated Barrier Hopping (CBH) model. With 30.92% tenability and a figure of merit of 13 at room temperature and 1 kHz frequency, combined with a stable relative permittivity around 200 with a maximum variation of 6% over a temperature range of 200 °C and low loss tangent, the compound might have some tenability applications.

Design of a new reactor-like high temperature near ambient pressure scanning tunneling microscope for catalysis studies.

PubMed

Tao, Franklin Feng; Nguyen, Luan; Zhang, Shiran

2013-03-01

Here, we present the design of a new reactor-like high-temperature near ambient pressure scanning tunneling microscope (HT-NAP-STM) for catalysis studies. This HT-NAP-STM was designed for exploration of structures of catalyst surfaces at atomic scale during catalysis or under reaction conditions. In this HT-NAP-STM, the minimized reactor with a volume of reactant gases of ∼10 ml is thermally isolated from the STM room through a shielding dome installed between the reactor and STM room. An aperture on the dome was made to allow tip to approach to or retract from a catalyst surface in the reactor. This dome minimizes thermal diffusion from hot gas of the reactor to the STM room and thus remains STM head at a constant temperature near to room temperature, allowing observation of surface structures at atomic scale under reaction conditions or during catalysis with minimized thermal drift. The integrated quadrupole mass spectrometer can simultaneously measure products during visualization of surface structure of a catalyst. This synergy allows building an intrinsic correlation between surface structure and its catalytic performance. This correlation offers important insights for understanding of catalysis. Tests were done on graphite in ambient environment, Pt(111) in CO, graphene on Ru(0001) in UHV at high temperature and gaseous environment at high temperature. Atom-resolved surface structure of graphene on Ru(0001) at 500 K in a gaseous environment of 25 Torr was identified.

Symmetries and multiferroic properties of novel room-temperature magnetoelectrics: Lead iron tantalate – lead zirconate titanate (PFT/PZT)

DOE PAGES

Sanchez, Dilsom A.; Ortega, N.; Kumar, Ashok; ...

2011-12-05

Mixing 60-70% lead zirconate titanate with 40-30% lead iron tantalate produces a single-phase, low-loss, room-temperature multiferroic with magnetoelectric coupling: (PbZr 0.53Ti 0.47O 3) (1-x)- (PbFe 0.5Ta 0.5O 3) x. Our study combines x-ray scattering, magnetic and polarization hysteresis in both phases, plus a second-order dielectric divergence (to epsilon = 6000 at 475 K for 0.4 PFT; to 4000 at 520 K for 0.3 PFT) for an unambiguous assignment as a C 2v-C 4v (Pmm2-P4mm) transition. Furthermore, the material exhibits square saturated magnetic hysteresis loops with 0.1 emu/g at 295 K and saturation polarization P r = 25 μC/cm 2, whichmore » actually increases (to 40 μC/cm 2) in the high-T tetragonal phase, representing an exciting new room temperature oxide multiferroic to compete with BiFeO 3. Additional transitions at high temperatures (cubic at T>1300 K) and low temperatures (rhombohedral or monoclinic at T<250 K) are found. Finally, these are the lowest-loss room-temperature multiferroics known, which is a great advantage for magnetoelectric devices.« less

Room temperature ferromagnetism of tin oxide nanocrystal based on synthesis methods

NASA Astrophysics Data System (ADS)

Sakthiraj, K.; Hema, M.; Balachandrakumar, K.

2016-04-01

The experimental conditions used in the preparation of nanocrystalline oxide materials play an important role in the room temperature ferromagnetism of the product. In the present work, a comparison was made between sol-gel, microwave assisted sol-gel and hydrothermal methods for preparing tin oxide nanocrystal. X-ray diffraction analysis indicates the formation of tetragonal rutile phase structure for all the samples. The crystallite size was estimated from the HRTEM images and it is around 6-12 nm. Using optical absorbance measurement, the band gap energy value of the samples has been calculated. It reveals the existence of quantum confinement effect in all the prepared samples. Photoluminescence (PL) spectra confirms that the luminescence process originates from the structural defects such as oxygen vacancies present in the samples. Room temperature hysteresis loop was clearly observed in M-H curve of all the samples. But the sol-gel derived sample shows the higher values of saturation magnetization (Ms) and remanence (Mr) than other two samples. This study reveals that the sol-gel method is superior to the other two methods for producing room temperature ferromagnetism in tin oxide nanocrystal.

Low dimensional CH3NH3PbBr3 cubes for persistent luminescence: Energy variation of electron excitation

NASA Astrophysics Data System (ADS)

Besral, N.; Paul, T.; Thakur, S.; Sarkar, S.; Sardar, K.; Chanda, K.; Das, A.; Chattopadhyay, K. K.

2018-04-01

The impact of varying electron beam voltage upon room temperature CL (cathodoluminescence) properties of crystalline organic-inorganic lead halide perovskite CH3NH3PbBr3 (Methylammonium lead tribromide) microcubes have been studied. CH3NH3PbBr3 microcubes were synthesized at room temperature by a very straight forward wet chemical route. After preliminary characterizations like XRD (X-ray diffraction), FESEM (Field emission scanning electron microscopy), UV-Vis spectroscopy, CL study at three different beam voltages i.e. 5 kV, 10 kV and 15 kV respectively was performed at room temperature. Prominent emission signals were obtained with emission peaks at 2.190 eV (FWHM 0.120 eV), 2.222 eV (FWHM 0.108 eV) and 2.242 eV (FWHM 0.095 eV) for electron beam voltages 5 kV, 10 kV and 15 kV respectively.

Thermostability of bovine submaxillary mucin (BSM) in bulk solution and at a sliding interface.

PubMed

Madsen, Jan Busk; Pakkanen, Kirsi I; Lee, Seunghwan

2014-06-15

Thermostability of bovine submaxillary mucin (BSM) was studied in terms of its structure, hydrodynamic size, surface adsorption, and lubricating properties in the temperature range of 5-85°C. The overall random coil structure of BSM showed a gradual loosening with increasing temperature as characterized by circular dichroism (CD) spectroscopy, but this change was fully reversible upon lowering temperature. Extended heating up to 120 min at 80°C did not make any appreciable changes in the structure of BSM when it was cooled to room temperature. The hydrodynamic size of BSM, as studied by dynamic light scattering (DLS), showed a slight increase after heating at high temperature (80°C). Optical waveguide lightmode spectroscopy (OWLS) studies showed facile adsorption of BSM onto poly(dimethylsiloxane) (PDMS) surface (>180 ng/cm(2)) at room temperature due to its amphiphilic characteristics. Adsorbed mass of BSM was noticeably reduced after heating at 80°C, possibly resulting from its aggregation. BSM showed excellent lubricity at self-mated sliding contacts between PDMS at room temperature or lower (friction coefficient≈0.02), even when BSM solution was pre-heated up to 120 min at 80°C. Gradual degradation of lubricity of BSM was observed with increasing temperature, but it was also reversibly recovered with decreasing temperature. Structural and functional stability of BSM against heating is proposed to originate from heavy glycosylation and lack of higher degree of protein structure in BSM. Copyright © 2014 Elsevier Inc. All rights reserved.

Stability of headspace volatiles in a ‘Fallglo’ tangerine juice matrix system at room temperature

USDA-ARS?s Scientific Manuscript database

Gas chromatography systems are usually equipped with autosamplers. Samples held in the autosampler tray can stay up to one day or longer at room temperature, if the tray is not equipped with a cooling mechanism. The objective of this research was to determine if holding samples at room temperature i...

High temperature coefficient of resistance achieved by ion beam assisted sputtering with no heat treatment in V{sub y}M{sub 1−y}O{sub x} (M = Nb, Hf)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vardi, Naor; Sharoni, Amos, E-mail: amos.sharoni@biu.ac.il

2015-11-15

Thermal imaging based on room temperature bolometer sensors is a growing market, constantly searching for improved sensitivity. One important factor is the temperature coefficient of resistance (TCR), i.e., the sensitivity of the active material. Herein, the authors report the improved TCR properties attainable by the “ion beam assisted deposition” method for room temperature deposition. V{sub y}M{sub 1−y}O{sub x} (M = Nb, Hf) thin-film alloys were fabricated on 1 μm thermal SiO{sub 2} atop Si (100) substrates by reactive magnetron cosputtering at room temperature using a low energy ion source, aimed at the film, to insert dissociated oxygen species and increase film density. Themore » authors studied the influence of deposition parameters such as oxygen partial pressure, V to M ratio, and power of the plasma source, on resistance and TCR. The authors show high TCR (up to −3.7% K{sup −1}) at 300 K, and excellent uniformity, but also an increase in resistance. The authors emphasize that samples were prepared at room temperature with no heat treatment, much simpler than common processes that require annealing at high temperatures. So, this is a promising fabrication route for uncooled microbolometers.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Welch, B.L.; Briggs, S.F.; Johansen, J.H.

Big sagebrush (Artemisia tridentata Nutt.) seeds were stored in three different environments; cool, constant temperature (refrigerator 10 degs. C); room temperature (14 to 24 degs. C); and a nonheated warehouse (-28 to +44 degs. C). In all three cases, humidity was held constant and equal. Significant drop in seed viability occurred first in the seed stored in the nonheated warehouse, followed by seed stored at room temperatures, and then seed stored at cool temperatures. It appeared from this study and studies by others that humidity control is more important to maintaining seed viability than temperature control. The old adage simplymore » states `store seeds in a cool and dry place` - but first make sure the seeds have been properly dried. Drying sagebrush seed during the cool, wet weather of the harvesting period creates special challenges to the producer.« less

In Vivo Intracanal Temperature Evolution during Endodontic Treatment after the Injection of Room Temperature or Preheated Sodium Hypochlorite.

PubMed

de Hemptinne, Ferdinand; Slaus, Gunter; Vandendael, Mathieu; Jacquet, Wolfgang; De Moor, Roeland J; Bottenberg, Peter

2015-07-01

Heating a sodium hypochlorite solution improves its effectiveness. The aim of this study was to measure the in vivo temperature changes of sodium hypochlorite solutions that were initially preheated to 66°C or at room temperature inside root canals during routine irrigation. Thirty-five root canals were prepared to ISO size 40 with 4% taper. A type K (nickel-chromium-nickel) thermocouple microprobe (Testo NV, Ternat, Belgium) was positioned within 3 mm of the working length to measure the temperature at 1-second intervals. In each canal, 2 test protocols were evaluated in a randomized order with 3% sodium hypochlorite solutions: (1) preheated to 66°C and (2) at room temperature. The temperature measurements began 5 seconds before the 25 seconds of irrigant injections and continued for 240 seconds. This resulted in 270 data points for each protocol. The temperature of the irrigant at room temperature increased from the initial intracanal temperature after injection of 20.7°C (±1.2°C) to 30.9°C (±1.3°C) in 10 seconds and to 35°C (±0.9°C) after 240 seconds. The temperature of the preheated to 66°C solution decreased from 56.4°C (±2.7°C) to 45.4°C (±3.0°C) after 5 seconds, reached 37°C (±0.9°C) after 60 seconds, and reached 35.7°C (±0.8°C) after 240 seconds. The original temperatures of the sodium hypochlorite solutions were buffered inside the root canal and tended to rapidly evolve to equilibrium. The findings of this study contribute to an improved understanding of the thermodynamic behaviors of irrigant solutions inside root canals in vivo. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Proinsulin is stable at room temperature for 24 hours in EDTA: A clinical laboratory analysis (adAPT 3).

PubMed

Davidson, Jane; McDonald, Timothy; Sutherland, Calum; Mostazir, Mohammod; VanAalten, Lidy; Wilkin, Terence

2017-01-01

Reference laboratories advise immediate separation and freezing of samples for the assay of proinsulin, which limit its practicability for smaller centres. Following the demonstration that insulin and C-peptide are stable in EDTA at room temperature for at least 24hours, we undertook simple stability studies to establish whether the same might apply to proinsulin. Venous blood samples were drawn from six adult women, some fasting, some not, aliquoted and assayed immediately and after storage at either 4°C or ambient temperature for periods from 2h to 24h. There was no significant variation or difference with storage time or storage condition in either individual or group analysis. Proinsulin appears to be stable at room temperature in EDTA for at least 24h. Immediate separation and storage on ice of samples for proinsulin assay is not necessary, which will simplify sample transport, particularly for multicentre trials.

Large spin accumulation and crystallographic dependence of spin transport in single crystal gallium nitride nanowires

PubMed Central

Park, Tae-Eon; Park, Youn Ho; Lee, Jong-Min; Kim, Sung Wook; Park, Hee Gyum; Min, Byoung-Chul; Kim, Hyung-jun; Koo, Hyun Cheol; Choi, Heon-Jin; Han, Suk Hee; Johnson, Mark; Chang, Joonyeon

2017-01-01

Semiconductor spintronics is an alternative to conventional electronics that offers devices with high performance, low power and multiple functionality. Although a large number of devices with mesoscopic dimensions have been successfully demonstrated at low temperatures for decades, room-temperature operation still needs to go further. Here we study spin injection in single-crystal gallium nitride nanowires and report robust spin accumulation at room temperature with enhanced spin injection polarization of 9%. A large Overhauser coupling between the electron spin accumulation and the lattice nuclei is observed. Finally, our single-crystal gallium nitride samples have a trigonal cross-section defined by the (001), () and () planes. Using the Hanle effect, we show that the spin accumulation is significantly different for injection across the (001) and () (or ()) planes. This provides a technique for increasing room temperature spin injection in mesoscopic systems. PMID:28569767

Line Coupling Effects in the Isotropic Raman Spectra of N2: A Quantum Calculation at Room Temperature

NASA Technical Reports Server (NTRS)

Thibault, Franck; Boulet, Christian; Ma, Qiancheng

2014-01-01

We present quantum calculations of the relaxation matrix for the Q branch of N2 at room temperature using a recently proposed N2-N2 rigid rotor potential. Close coupling calculations were complemented by coupled states studies at high energies and provide about 10200 two-body state-to state cross sections from which the needed one-body cross-sections may be obtained. For such temperatures, convergence has to be thoroughly analyzed since such conditions are close to the limit of current computational feasibility. This has been done using complementary calculations based on the energy corrected sudden formalism. Agreement of these quantum predictions with experimental data is good, but the main goal of this work is to provide a benchmark relaxation matrix for testing more approximate methods which remain of a great utility for complex molecular systems at room (and higher) temperatures.

Gas phase recovery of hydrogen sulfide contaminated polymer electrolyte membrane fuel cells

NASA Astrophysics Data System (ADS)

Kakati, Biraj Kumar; Kucernak, Anthony R. J.

2014-04-01

The effect of hydrogen sulfide (H2S) on the anode of a polymer electrolyte membrane fuel cell (PEMFC) and the gas phase recovery of the contaminated PEMFC using ozone (O3) were studied. Experiments were performed on fuel cell electrodes both in an aqueous electrolyte and within an operating fuel cell. The ex-situ analyses of a fresh electrode; a H2S contaminated electrode (23 μmolH2S cm-2); and the contaminated electrode cleaned with O3 shows that all sulfide can be removed within 900 s at room temperature. Online gas analysis of the recovery process confirms the recovery time required as around 720 s. Similarly, performance studies of an H2S contaminated PEMFC shows that complete rejuvenation occurs following 600-900 s O3 treatment at room temperature. The cleaning process involves both electrochemical oxidation (facilitated by the high equilibrium potential of the O3 reduction process) and direct chemical oxidation of the contaminant. The O3 cleaning process is more efficient than the external polarization of the single cell at 1.6 V. Application of O3 at room temperature limits the amount of carbon corrosion. Room temperature O3 treatment of poisoned fuel cell stacks may offer an efficient and quick remediation method to recover otherwise inoperable systems.

Spin relaxation dynamics of holes in intrinsic GaAs quantum wells studied by transient circular dichromatic absorption spectroscopy at room temperature.

PubMed

Fang, Shaoyin; Zhu, Ruidan; Lai, Tianshu

2017-03-21

Spin relaxation dynamics of holes in intrinsic GaAs quantum wells is studied using time-resolved circular dichromatic absorption spectroscopy at room temperature. It is found that ultrafast dynamics is dominated by the cooperative contributions of band filling and many-body effects. The relative contribution of the two effects is opposite in strength for electrons and holes. As a result, transient circular dichromatic differential transmission (TCD-DT) with co- and cross-circularly polarized pump and probe presents different strength at several picosecond delay time. Ultrafast spin relaxation dynamics of excited holes is sensitively reflected in TCD-DT with cross-circularly polarized pump and probe. A model, including coherent artifact, thermalization of nonthermal carriers and the cooperative contribution of band filling and many-body effects, is developed, and used to fit TCD-DT with cross-circularly polarized pump and probe. Spin relaxation time of holes is achieved as a function of excited hole density for the first time at room temperature, and increases with hole density, which disagrees with a theoretical prediction based on EY spin relaxation mechanism, implying that EY mechanism may be not dominant hole spin relaxation mechanism at room temperature, but DP mechanism is dominant possibly.

Radiation-induced hydroxyl addition to purine molecules: EPR and ENDOR study of hypoxanthine hydrochloride monohydrate single crystals.

PubMed

Tokdemir, Sibel; Nelson, William H

2005-06-01

Three radical species were detected in an EPR/ENDOR study of X-irradiated hypoxanthine.HCl.H2O single crystals at room temperature: RI was identified as the product of net H addition to C8, RII was identified as the product of net H addition to C2, and RIII was identified as the product of OH addition to C8. The observed set of radicals was the same for room-temperature irradiation as for irradiation at 10 K followed by warming the crystals to room temperature; however, the C2 H-addition and C8 OH-addition radicals were not detectable after storage of the crystals for about 2 months at room temperature. Use of selectively deuterated crystals permitted unique assignment of the observed hyperfine couplings, and results of density functional theory calculations on each of the radical structures were consistent with the experimental results. Comparison of these experimental results with others from previous crystal-based systems and model system computations provides insight into the mechanisms by which the biologically important purine C8 hydroxyl addition products are formed. The evidence from solid systems supports the mechanism of net water addition to one-electron oxidized purine bases and demonstrates the importance of a facial approach between the reactants.

Use of near-IR to monitor the influence of external heating on dental composite photopolymerization.

PubMed

Trujillo, Marianela; Newman, Sheldon M; Stansbury, Jeffrey W

2004-10-01

This study was conducted to determine the effect of modest external heating on the photopolymerization kinetics and conversion of commercial dental composite restorative materials. A transmission-mode, real-time near-infrared spectroscopic technique was used to monitor the photopolymerization process in the composite materials at various temperatures between 23 and 70 degrees C. Several light curing units, differing in spectral output and power densities were compared at the different cure temperatures. Several significantly different commercial composites were compared for their response. Regardless of the curing light or composite material used, photopolymerization at a moderate curing temperature of 54.5 degrees C resulted in significantly higher immediate and final conversion values compared with room temperature photocuring. Contrary to the room temperature cured materials, at the elevated cure temperature the extent of post-cure was minor and different curing lights produced very uniform conversion values within a given material. The time required to reach a given level of conversion, established as full conversion with the room temperature cure, was reduced typically by 80-90% using the elevated curing conditions. Complementary kinetic studies confirmed the effect of cure temperature on increasing the polymerization rate in dental composites as significant. Increasing the temperature of composite resin within potentially biologically compatible limits can significantly influences resin polymerization. These increased rates and conversion could lead to improved properties of composite restorative materials.

Room-temperature multiferroic and magnetocapacitance effects in M-type hexaferrite BaFe10.2Sc1.8O19

NASA Astrophysics Data System (ADS)

Tang, Rujun; Zhou, Hao; You, Wenlong; Yang, Hao

2016-08-01

The room-temperature multiferroic and magnetocapacitance (MC) effects of polycrystalline M-type hexaferrite BaFe10.2Sc1.8O19 have been investigated. The results show that the magnetic moments of insulating BaFe10.2Sc1.8O19 can be manipulated by the electric field at room temperature, indicating the existence of magnetoelectric coupling. Moreover, large MC effects are also observed around the room temperature. A frequency dependence analysis shows that the Maxwell-Wagner type magnetoresistance effect is the dominant mechanism for MC effects at low frequencies. Both the magnetoelectric-type and non-magnetoelectric-type spin-phonon couplings contribute to the MC effects at high frequencies with the former being the dominant mechanism. The above results show that the hexaferrite BaFe10.2Sc1.8O19 is a room-temperature multiferroic material that can be potentially used in magnetoelectric devices.

Dual origin of room temperature sub-terahertz photoresponse in graphene field effect transistors

NASA Astrophysics Data System (ADS)

Bandurin, D. A.; Gayduchenko, I.; Cao, Y.; Moskotin, M.; Principi, A.; Grigorieva, I. V.; Goltsman, G.; Fedorov, G.; Svintsov, D.

2018-04-01

Graphene is considered as a promising platform for detectors of high-frequency radiation up to the terahertz (THz) range due to its superior electron mobility. Previously, it has been shown that graphene field effect transistors (FETs) exhibit room temperature broadband photoresponse to incoming THz radiation, thanks to the thermoelectric and/or plasma wave rectification. Both effects exhibit similar functional dependences on the gate voltage, and therefore, it was difficult to disentangle these contributions in previous studies. In this letter, we report on combined experimental and theoretical studies of sub-THz response in graphene field-effect transistors analyzed at different temperatures. This temperature-dependent study allowed us to reveal the role of the photo-thermoelectric effect, p-n junction rectification, and plasmonic rectification in the sub-THz photoresponse of graphene FETs.

On-site chemical pre-lithiation of S cathode at room temperature on a 3D nano-structured current collector

NASA Astrophysics Data System (ADS)

Wu, Yunwen; Momma, Toshiyuki; Ahn, Seongki; Yokoshima, Tokihiko; Nara, Hiroki; Osaka, Tetsuya

2017-10-01

This work reports a new chemical pre-lithiation method to fabricate lithium sulfide (Li2S) cathode. This pre-lithiation process is taken place simply by dropping the organolithium reagent lithium naphthalenide (Li+Naph-) on the prepared sulfur cathode. It is the first time realizing the room temperature chemical pre-lithaition reaction attributed by the 3D nanostructured carbon nanotube (CNT) current collector. It is confirmed that the Li2S cathode fabricated at room temperature showing higher capacity and lower hysteresis than the Li2S cathode fabricated at high temperature pre-lithiation. The pre-lithiated Li2S cathode at room temperature shows stable cycling performance with a 600 mAh g-1 capacity after 100 cycles at 0.1 C-rate and high capacity of 500 mAh g-1 at 2 C-rate. This simple on-site pre-lithiation method at room temperature is demonstrated to be applicable for the in-situ pre-lithiation in a Li metal free battery.

Room-Temperature Spin-Orbit Torque Switching Induced by a Topological Insulator

NASA Astrophysics Data System (ADS)

Han, Jiahao; Richardella, A.; Siddiqui, Saima A.; Finley, Joseph; Samarth, N.; Liu, Luqiao

2017-08-01

The strongly spin-momentum coupled electronic states in topological insulators (TI) have been extensively pursued to realize efficient magnetic switching. However, previous studies show a large discrepancy of the charge-spin conversion efficiency. Moreover, current-induced magnetic switching with TI can only be observed at cryogenic temperatures. We report spin-orbit torque switching in a TI-ferrimagnet heterostructure with perpendicular magnetic anisotropy at room temperature. The obtained effective spin Hall angle of TI is substantially larger than the previously studied heavy metals. Our results demonstrate robust charge-spin conversion in TI and provide a direct avenue towards applicable TI-based spintronic devices.

Nucleoside phosphorylation in amide solutions

NASA Technical Reports Server (NTRS)

Schoffstall, A. M.; Kokko, B.

1978-01-01

The paper deals with phosphorylation in possible prebiotic nonaqueous solvents. To this end, phosphorylation of nucleosides using inorganic phosphates in amide solutions is studied at room and elevated temperatures. Reaction proceeds most readily in formamide and N-methylformamide. Products obtained at elevated temperature are nucleotides, nucleoside 2',3'-cyclic phosphates, and when the phosphate concentration is high, nucleoside diphosphates. At room temperature, adenosine afforded a mixture of nucleotides, but none of the cyclic nucleotide. Conditions leading to the highest relative percentage of cyclic nucleotide involve the use of low concentrations of phosphate and an excess of nucleoside.

Ab-initio calculation and experimental observation of room temperature ferromagnetism in 50 keV nitrogen implanted rutile TiO2

NASA Astrophysics Data System (ADS)

Luitel, Homnath; Chakrabarti, Mahuya; Sarkar, A.; Dechoudhury, S.; Bhowmick, D.; Naik, V.; Sanyal, D.

2018-02-01

Room temperature magnetic properties of 50 keV N4+ ion beam implanted rutile TiO2 have been theoretically and experimentally studied. Ab-initio calculation under the frame work of density functional theory has been carried out to study the magnetic properties of the different possible nitrogen related defects in TiO2. Spin polarized density of states calculation suggests that both Ninst and NO can induce ferromagnetic ordering in rutile TiO2. In both cases the 2p orbital electrons of nitrogen atom give rise to the magnetic moment in TiO2. The possibility of the formation of N2 molecule in TiO2 system is also studied but in this case no significant magnetic moment has been observed. The magnetic measurements, using SQUID magnetometer, results a ferromagnetic ordering even at room temperature for the 50 keV N4+ ion beam implanted rutile TiO2.

Hydrogen-atmosphere induction furnace has increased temperature range

NASA Technical Reports Server (NTRS)

Caves, R. M.; Gresslin, C. H.

1966-01-01

Improved hydrogen-atmosphere induction furnace operates at temperatures up to 5,350 deg F. The furnace heats up from room temperature to 4,750 deg F in 30 seconds and cools down to room temperature in 2 minutes.

Heat transfer capability of solar radiation in colored roof and influence on room thermal comfort

NASA Astrophysics Data System (ADS)

Syuhada, Ahmad; Maulana, Muhammad Ilham

2018-02-01

Colored zinc is the most widely used by people in Indonesia as the roof of the building. Each color has different heat absorption capability, the higher the absorption capacity of a roof will cause high room temperature. A high temperature in the room will cause the room is not thermally comfortable for activity. Lack of public knowledge about the ability of each color to absorb heat can cause errors in choosing the color of the roof of the building so that it becomes uncomfortable regarding thermal comfort. This study examined how big the ability of each color in influencing the heat absorption on the roof of the zinc. The purpose of this study is to examine which colors are the lowest to absorb radiation heat. This research used theexperimental method. Data collected by measuring the temperature of the environment above and below the colored tin roof, starting at 11:00 am until 15:00 pm. The zinc roofs tested in this study are zinc black, red zinc, green zinc, blue zinc, brown zinc, maroon zinc, orange zinc, zinc gray, zinc color chrome and zinc white color. The study results show that black and blackish colors will absorb more heat than other colors. While the color white or close to whitish color will absorb a slight heat.

Methods to reduce the CO(2) concentration of educational buildings utilizing internal ventilation by transferred air.

PubMed

Kalema, T; Viot, M

2014-02-01

The aim of this study is to develop internal ventilation by transferred air to achieve a good indoor climate with low energy consumption in educational buildings with constant air volume (CAV) ventilation. Both measurements of CO2 concentration and a multi-room calculation model are presented. The study analyzes how to use more efficiently the available spaces and the capacity of CAV ventilation systems in existing buildings and the impact this has on the indoor air quality and the energy consumption of the ventilation. The temperature differences can be used to create natural ventilation airflows between neighboring spaces. The behavior of temperature-driven airflows between rooms was studied and included in the calculation model. The effect of openings between neighboring spaces, such as doors or large apertures in the walls, on the CO2 concentration was studied in different classrooms. The air temperatures and CO2 concentrations were measured using a wireless, internet-based measurement system. The multi-room calculation model predicted the CO2 concentration in the rooms, which was then compared with the measured ones. Using transferred air between occupied and unoccupied spaces can noticeably reduce the total mechanical ventilation rates needed to keep a low CO2 concentration. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A systematic review of randomised controlled trials of the effects of warmed irrigation fluid on core body temperature during endoscopic surgeries.

PubMed

Jin, Yinghui; Tian, Jinhui; Sun, Mei; Yang, Kehu

2011-02-01

The purpose of this systematic review was to establish whether warmed irrigation fluid temperature could decrease the drop of body temperature and incidence of shivering and hypothermia. Irrigation fluid, which is used in large quantities during endoscopic surgeries at room temperature, is considered to be associated with hypothermia and shivering. It remains controversial whether using warmed irrigation fluid to replace room-temperature irrigation fluid will decrease the drop of core body temperature and the occurrence of hypothermia. A comprehensive search (computerised database searches, footnote chasing, citation chasing) was undertaken to identify all the randomised controlled trials that explored temperature of irrigation fluid in endoscopic surgery. An approach involving meta-analysis was used. We searched PubMed, EMBASE, Cochrane Library, SCI, China academic journals full-text databases, Chinese Biomedical Literature Database, Chinese scientific journals databases and Chinese Medical Association Journals for trials that meet the inclusion criteria. Study quality was assessed using standards recommended by Cochrane Library Handbook 5.0.1. Disagreement was resolved by consensus. Thirteen randomised controlled trials including 686 patients were identified. The results showed that room-temperature irrigation fluid caused a greater drop of core body temperature in patients, compared to warmed irrigation fluid (p < 0.00001; I(2) = 85%). The occurrence of shivering [odds ratio (OR) 5.13, 95% CI: 2.95-10.19, p < 0.00001; I(2) = 0%] and hypothermia (OR 22.01, 95% CI: 2.03-197.08, p = 0.01; I(2) = 64%) in the groups having warmed irrigation fluid were lower than the group of studies having room-temperature fluid. In endoscopic surgeries, irrigation fluid is recommended to be warmed to decrease the drop of core body temperature and the risk of perioperative shivering and hypothermia. Warming irrigating fluid should be considered standard practice in all endoscopic surgeries. © 2011 Blackwell Publishing Ltd.

Short-Term Storage of Platelet-Rich Plasma at Room Temperature Does Not Affect Growth Factor or Catabolic Cytokine Concentration.

PubMed

Wilson, Brooke H; Cole, Brian J; Goodale, Margaret B; Fortier, Lisa A

2018-04-01

The aim of this study was to provide clinical recommendations about the use of platelet-rich plasma (PRP) that was subjected to short-term storage at room temperature. We determined bioactive growth factor and cytokine concentrations as indicators of platelet and white blood cell degranulation in blood and PRP. Additionally, this study sought to validate the use of manual, direct smear analysis as an alternative to automated methods for platelet quantification in PRP. Blood was used to generate low-leukocyte PRP (Llo PRP) or high-leukocyte PRP (Lhi PRP). Blood was either processed immediately or kept at room temperature for 2 or 4 hours prior to generation of PRP, which was then held at room temperature for 0, 1, 2, or 4 hours. Subsequently, bioactive transforming growth factor beta-1 and matrix metalloproteinase-9 were measured by ELISA (enzyme-linked immunosorbent assay). Manual and automated platelet counts were performed on all blood and PRP samples. There were no differences in growth factor or cytokine concentration when blood or Llo PRP or Lhi PRP was retained at room temperature for up to 4 hours. Manual, direct smear analysis for platelet quantification was not different from the use of automated machine counting for PRP samples, but in the starting blood samples, manual platelet counts were significantly higher than those generated using automated technology. When there is a delay of up to 4 hours in the generation of PRP from blood or in the application of PRP to the patient, bioactive growth factor and cytokine concentrations remain stable in both blood and PRP. A manual direct counting method is a simple, cost-effective, and valid method to measure the contents of the PRP product being delivered to the patient.

Highly sensitive response of solution-processed bismuth sulfide nanobelts for room-temperature nitrogen dioxide detection.

PubMed

Kan, Hao; Li, Min; Song, Zhilong; Liu, Sisi; Zhang, Baohui; Liu, Jingyao; Li, Ming-Yu; Zhang, Guangzu; Jiang, ShengLin; Liu, Huan

2017-11-15

Low dimensional nanomaterials have emerged as candidates for gas sensors owing to their unique size-dependent properties. In this paper, Bi 2 S 3 nanobelts were synthesized via a facile solvothermal process and spin-coated onto alumina substrates at room temperature. The conductometric devices can even sensitively response to the relatively low concentrations of NO 2 at room temperature, and their sensing performance can be effectively enhanced by the ligand exchange treatment with inorganic salts. The Pb(NO 3 ) 2 -treated device exhibited superior sensing performance of 58.8 under 5ppm NO 2 at room-temperature, with the response and recovery time of 28 and 106s. The competitive adsorption of NO 2 against O 2 on Bi 2 S 3 nanobelts, with the enhancement both in gas adsorption and charge transfer caused by the porous network of the very thin Bi 2 S 3 nanobelts, can be a reasonable explanation for the improved performance at room temperature. Their sensitive room-temperature response behaviors combined with the excellent solution processability, made Bi 2 S 3 nanobelts very attractive for the construction of low-cost gas sensors with lower power consumption. Copyright © 2017 Elsevier Inc. All rights reserved.

The influence of storage time and temperature on the measurement of serum, plasma and urine osmolality.

PubMed

Bezuidenhout, Karla; Rensburg, Megan A; Hudson, Careen L; Essack, Younus; Davids, M Razeen

2016-07-01

Many clinical laboratories require that specimens for serum and urine osmolality determination be processed within 3 h of sampling or need to arrive at the laboratory on ice. This protocol is based on the World Health Organization report on sample storage and stability, but the recommendation lacks good supporting data. We studied the effect of storage temperature and time on osmolality measurements. Blood and urine samples were obtained from 16 patients and 25 healthy volunteers. Baseline serum, plasma and urine osmolality measurements were performed within 30 min. Measurements were then made at 3, 6, 12, 24 and 36 h on samples stored at 4-8℃ and room temperature. We compared baseline values with subsequent measurements and used difference plots to illustrate changes in osmolality. At 4-8℃, serum and plasma osmolality were stable for up to 36 h. At room temperature, serum and plasma osmolality were very stable for up to 12 h. At 24 and 36 h, changes from baseline osmolality were statistically significant and exceeded the total allowable error of 1.5% but not the reference change value of 4.1%. Urine osmolality was extremely stable at room temperature with a mean change of less than 1 mosmol/kg at 36 h. Serum and plasma samples can be stored at room temperature for up to 36 h before measuring osmolality. Cooling samples to 4-8℃ may be useful when delays in measurement beyond 12 h are anticipated. Urine osmolality is extremely stable for up to 36 h at room temperature. © The Author(s) 2015.

Association Between Fungal Contamination and Eye Bank-Prepared Endothelial Keratoplasty Tissue: Temperature-Dependent Risk Factors and Antifungal Supplementation of Optisol-Gentamicin and Streptomycin.

PubMed

Brothers, Kimberly M; Shanks, Robert M Q; Hurlbert, Susan; Kowalski, Regis P; Tu, Elmer Y

2017-11-01

Fungal contamination and infection from donor tissues processed for endothelial keratoplasty is a growing concern, prompting analysis of donor tissues after processing. To determine whether eyebank-processed endothelial keratoplasty tissue is at higher risk of contamination than unprocessed tissue and to model eyebank processing with regard to room temperature exposure on Candida growth in optisol-gentamicin and streptomycin (GS) with and without antifungal supplementation. An examination of the 2013 Eversight Eyebank Study follow-up database for risk factors associated with post-keratoplasty infection identified an increased risk of positive fungal rim culture results in tissue processed for endothelial keratoplasty vs unprocessed tissue. Processing steps at room temperature were hypothesized as a potential risk factor for promotion of fungal growth between these 2 processes. Candida albicans, Candida glabrata, and Candida parapsilosis endophthalmitis isolates were each inoculated into optisol-GS and subjected to 2 different room temperature incubation regimens reflective of current corneal tissue handling protocols. Eversight Eyebank Study outcomes and measures were follow-up inquiries from 6592 corneal transplants. Efficacy study outcomes and measures were fungal colony-forming units from inoculated vials of optisol-GS taken at 2 different processing temperatures. Donor rim culture results were 3 times more likely to be positive for fungi in endothelial keratoplasty-processed eyes (1.14%) than for other uses (0.37%) (difference, 0.77%; 95% CI, 0.17-.1.37) (P = .009). In vitro, increased room temperature incubation of optisol-GS increased growth of Candida species over time. The addition of caspofungin and voriconazole decreased growth of Candida in a species-dependent manner. Detectable Candida growth in donor rim cultures, associated with a higher rate of post keratoplasty infection, is seen in endothelial keratoplasty tissue vs other uses at the time of transplantation, likely owing in part to eyebank preparation processes extending the time of tissue warming. Reduced room temperature incubation and the addition of antifungal agents decreased growth of Candida species in optisol-GS and should be further explored to reduce the risk of infection.

Investigation of tension-compression fatigue behavior of a cross-ply metal matrix composite at room and elevated temperatures. Master's thesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boyum, E.A.

1993-12-01

This research, the first load-controlled tension-compression fatigue testing to be performed on a MMC, extends the existing knowledge of MMC fatigue damage mechanisms to include the tension compression loading condition. To accomplish this, a (0/90)2, SCS-6/Ti-15-3 laminate was subjected to tension-tension fatigue at room temperature, and tension-compression fatigue at both room temperature and 427 deg C. Stress and strain data was taken to evaluate the macro-mechanic behavior of the material. Microscopy and fractography were performed to characterize the damage on a micro-mechanic level. On a maximum applied stress basis, the room temperature tension-tension specimens had longer fatigue lives than themore » room temperature tension-compression specimens. The room and high temperature tension-compression fatigue lives were nearly identical in the fiber-dominated high stress region of the SN curve. However, the increased ductility and diffused plasticity of the titanium matrix at 427 deg C delayed the onset and severity of matrix cracking, and thus increased the elevated temperature fatigue lives in the matrix dominated region of the SN curve. In all cases, matrix damage initiated at reaction zone cracks which nucleated both matrix plasticity and matrix cracking. Metal matrix composite, Elevated temperature, Fatigue testing, Compression, Fully-reversed, Titanium, Silicon carbide.« less

Murder or Not? Cold Temperature Makes Criminals Appear to Be Cold-Blooded and Warm Temperature to Be Hot-Headed

PubMed Central

Gockel, Christine; Kolb, Peter M.; Werth, Lioba

2014-01-01

Temperature-related words such as cold-blooded and hot-headed can be used to describe criminal behavior. Words associated with coldness describe premeditated behavior and words associated with heat describe impulsive behavior. Building on recent research about the close interplay between physical and interpersonal coldness and warmth, we examined in a lab experiment how ambient temperature within a comfort zone influences judgments of criminals. Participants in rooms with low temperature regarded criminals to be more cold-blooded than participants in rooms with high temperature. Specifically, they were more likely to attribute premeditated crimes, ascribed crimes resulting in higher degrees of penalty, and attributed more murders to criminals. Likewise, participants in rooms with high temperature regarded criminals to be more hot-headed than participants in rooms with low temperature: They were more likely to attribute impulsive crimes. Results imply that cognitive representations of temperature are closely related to representations of criminal behavior and attributions of intent. PMID:24788725

Murder or not? Cold temperature makes criminals appear to be cold-blooded and warm temperature to be hot-headed.

PubMed

Gockel, Christine; Kolb, Peter M; Werth, Lioba

2014-01-01

Temperature-related words such as cold-blooded and hot-headed can be used to describe criminal behavior. Words associated with coldness describe premeditated behavior and words associated with heat describe impulsive behavior. Building on recent research about the close interplay between physical and interpersonal coldness and warmth, we examined in a lab experiment how ambient temperature within a comfort zone influences judgments of criminals. Participants in rooms with low temperature regarded criminals to be more cold-blooded than participants in rooms with high temperature. Specifically, they were more likely to attribute premeditated crimes, ascribed crimes resulting in higher degrees of penalty, and attributed more murders to criminals. Likewise, participants in rooms with high temperature regarded criminals to be more hot-headed than participants in rooms with low temperature: They were more likely to attribute impulsive crimes. Results imply that cognitive representations of temperature are closely related to representations of criminal behavior and attributions of intent.

Effect of acclimation training on physiological changes in a randomized controlled trial in hot-humid environment.

PubMed

Zhang, Lei; Bao, Ying-chun

2014-11-01

This study was aimed to explore the physiological changes and the effect of heat acclimation training via a randomized control trial study. Forty healthy male volunteers were chosen and divided into experimental group and control group randomly. Those in experimental group received heat acclimation training including but not limited to meditation, unarmed run, yoga, and stepping in hot lab environment. And then, subjective feeling, rectal temperature, average skin temperature, and sweat electrolytes concentration were detected in order to describe their physiological changes. Before and after the training, both groups received some tests and their 3 000 m run-race time, nervous reaction time and subjective perception scores were recorded to evaluate the effect of acclimation training. (1) There was no difference in 3 000 m between the 2 groups in the same environment. Subjects' 3 000 m race time in experimental group was obviously shortened than that in control group in room temperature environment (t = 2.326, P < 0.05). And subjects' 3 000 m race time in experimental group was obviously shortened than that in control group in hot-humid environment (t = 4.518, P < 0.01). (2) Subjects' reaction time (RT) in experimental group was shortened than that in control group in room temperature environment (Z = 11.258, P < 0.05). And Subjects' RT in experimental group was sharply shortened than that in control group in hot-humid environment (Z = 6.519, P < 0.01). (3) No difference between the experimental and control groups was observed in subjective perception score (SPS) in room temperature environment. But subjects' SPS in experimental group was obviously lowered than that in control group and in hot-humid environment (t = 17.958, P < 0.01).(4) Anal temperature (AT) was lowered during training, while the change of mean skin temperature (MST) was not significant. Sweat sodium concentration (SSC) was lowered during training. SPS continued to decrease and entered plateau on the 13th day after training.(5) After acclimation training, the working capacity of the experimental group in hot-humid environment was over 85% of that in room temperature environment. While subjects' working capacity in control group in hot-humid environment was about 80% of that in room temperature environment. Hot-humid environment acclimation training improved the working capacity. After training, subjects' working capacity in hot-humid environment remained over 85% of that in room temperature environment, which was higher than that of those subjects who did not take part in training.

High Accuracy Thermal Expansion Measurement At Cryogenic Temperatures

NASA Technical Reports Server (NTRS)

Stallcup, Michael; Presson, Joan; Tucker, James; Daspit, Gregory; Nein, Max

2003-01-01

A new, interferometer based system for measuring thermal expansion to an absolute accuracy of 20 ppb or better at cryogenic temperatures has been developed. Data from NIST Copper SRM 736 measured from room temperature to 15 K will be presented along with data from many other materials including beryllium, ULE, Zerodur, and composite materials. Particular attention will be given to a study by the Space Optics Manufacturing Technology Center (SOMTC) investigating the variability of ULE and beryllium materials used in the AMSD program. Approximately 20 samples of each material, tested from room temperature to below 30 K are compared as a function of billet location.

High Accuracy Thermal Expansion Measurement at Cryogenic Temperatures

NASA Technical Reports Server (NTRS)

Tucker, Jim; Despit, Gregory; Stallcup, Michael; Presson, Joan; Nein, Max

2003-01-01

A new, interferometer-based system for measuring thermal expansion to an absolute accuracy of 20 ppb or better at cryogenic temperatures has been developed. Data from NIST Copper SRM 736 measured from room temperature to 15 K will be presented along with data from many other materials including beryllium, ULE, Zerodur, and composite materials. Particular attention will be given to a study by the Space Optics Manufacturing Technology Center (SOMTC) investigating the variability of ULE and beryllium materials used in the AMSD program Approximately 20 samples of each material, tested from room temperature to below 30 K are compared as a function of billet location.

Adjustment of Conformational Flexibility is a Key Event in the Thermal Adaptation of Proteins

NASA Astrophysics Data System (ADS)

Zavodszky, Peter; Kardos, Jozsef; Svingor, Adam; Petsko, Gregory A.

1998-06-01

3-Isopropylmalate dehydrogenase (IPMDH, E.C. 1.1.1.85) from the thermophilic bacterium Thermus thermophilus HB8 is homologous to IPMDH from the mesophilic Escherichia coli, but has an approximately 17 degrees C higher melting temperature. Its temperature optimum is 22-25 degrees C higher than that of the E. coli enzyme; however, it is hardly active at room temperature. The increased conformational rigidity required to stabilize the thermophilic enzyme against heat denaturation might explain its different temperature-activity profile. Hydrogen/deuterium exchange studies were performed on this thermophilic-mesophilic enzyme pair to compare their conformational flexibilities. It was found that Th. thermophilus IPMDH is significantly more rigid at room temperature than E. coli IPMDH, whereas the enzymes have nearly identical flexibilities under their respective optimal working conditions, suggesting that evolutionary adaptation tends to maintain a ``corresponding state'' regarding conformational flexibility. These observations confirm that conformational fluctuations necessary for catalytic function are restricted at room temperature in the thermophilic enzyme, suggesting a close relationship between conformational flexibility and enzyme function.

Room-temperature superfluidity in a polariton condensate

NASA Astrophysics Data System (ADS)

Lerario, Giovanni; Fieramosca, Antonio; Barachati, Fábio; Ballarini, Dario; Daskalakis, Konstantinos S.; Dominici, Lorenzo; de Giorgi, Milena; Maier, Stefan A.; Gigli, Giuseppe; Kéna-Cohen, Stéphane; Sanvitto, Daniele

2017-09-01

Superfluidity--the suppression of scattering in a quantum fluid at velocities below a critical value--is one of the most striking manifestations of the collective behaviour typical of Bose-Einstein condensates. This phenomenon, akin to superconductivity in metals, has until now been observed only at prohibitively low cryogenic temperatures. For atoms, this limit is imposed by the small thermal de Broglie wavelength, which is inversely related to the particle mass. Even in the case of ultralight quasiparticles such as exciton-polaritons, superfluidity has been demonstrated only at liquid helium temperatures. In this case, the limit is not imposed by the mass, but instead by the small binding energy of Wannier-Mott excitons, which sets the upper temperature limit. Here we demonstrate a transition from supersonic to superfluid flow in a polariton condensate under ambient conditions. This is achieved by using an organic microcavity supporting stable Frenkel exciton-polaritons at room temperature. This result paves the way not only for tabletop studies of quantum hydrodynamics, but also for room-temperature polariton devices that can be robustly protected from scattering.

Direct observation of the magnetic domain evolution stimulated by temperature and magnetic field in PrMnGeSi alloy

NASA Astrophysics Data System (ADS)

Zuo, S. L.; Zhang, B.; Qiao, K. M.; Peng, L. C.; Li, R.; Xiong, J. F.; Zhang, Y.; Zhao, X.; Liu, D.; Zhao, T. Y.; Sun, J. R.; Hu, F. X.; Zhang, Y.; Shen, B. G.

2018-05-01

The magnetic domain evolution behavior under external field stimuli of temperature and magnetic field in PrMn2Ge0.4Si1.6 compound is investigated using Lorentz transmission electron microscopy. A spontaneous 180° magnetic domain is observed at room temperature and it changes with temperature. Dynamic magnetization process is related to the rotation of magnetic moments, resulting in the transforming of magnetic domains from 180° type to a uniform ferromagnetic state with almost no pinning effects under the in-plane magnetic field at room temperature. X-ray powder diffraction is performed on PrMn2Ge0.4Si1.6 at different temperatures to study the temperature dependence of crystal structure and lattice parameter.

Inverse Coarse-Graining: A New Tool for Molecular Design

DTIC Science & Technology

2010-12-16

simulations. When compared with the more general multiscale coarse-graining (MS-CG) method, the EF-CG method retains the transferable part of the CG...Y.; Yan, T.; Voth, G. A., A Multiscale coarse-graining study of liquid/vacuum interface of room-temperature ionic liquids with alkyl substituents of...Energetic Room Temperature Ionic Liquid 1-Hydroxyethyl-4Amino-1, 2, 4-Triazolium Nitrate (HEATN). J. Phys. Chem. B 2008, 112, 3121-3131. 6. Liu, P

Volatilization and Thermal Decomposition Mechanisms of Room-Temperature Ionic Liquids (PRE-PRINT)

DTIC Science & Technology

2017-03-07

Huang, X. J. & Chen, L. Q. “Novel room temperature molten salt electrolyte based on LiTFSI and acetamide for lithium batteries .” Electrochemistry...organic compounds (VOCs) used as industrial solvents with involatile liquids. RTILs also show promise for applications in fuel cells, batteries , solar...indicated that volatilization of these species occurs as a single ion pair. Recent ALS studies on the photoionization of other 1- alkyl-3

Thermal and structural alternations in CuAlMnNi shape memory alloy by the effect of different pressure applications

NASA Astrophysics Data System (ADS)

Canbay, Canan Aksu; Polat, Tercan

2017-09-01

In this work the effects of the applied pressure on the characteristic transformation temperatures, the high temperature order-disorder phase transitions, the variation in diffraction peaks and the surface morphology of the CuAlMnNi shape memory alloy was investigated. The evolution of the transformation temperatures was studied by differential scanning calorimetry (DSC) with different heating and cooling rates. The differential thermal analysis measurements were performed to obtain the ordered-disordered phase transformations from room temperature to 900 °C. The characteristic transformation temperatures and the thermodynamic parameters were highly sensitive to variations in the applied pressure and also the applied pressure affected the thermodynamic parameters. The activation energy of the sample according to applied pressure values calculated by Kissinger method. The structural changes of the samples were studied by X-ray diffraction (XRD) measurements and by optical microscope observations at room temperature.

Pre-analytical stability of the plasma proteomes based on the storage temperature

PubMed Central

2013-01-01

Background This study examined the effect of storage temperature on the protein profile of human plasma. Plasma samples were stored for 13 days at -80°C, -20°C, +4°C and room temperature (20-25°C) prior to proteomic analysis. The proteomic comparisons were based on the differences of mean intensity values of protein spots between fresh plasma samples (named “time zero”) and plasma samples stored at different temperatures. To better understand the thermally induced biochemical changes that may affect plasma proteins during storage we identified proteins with different expressions with respect to the time zero sample. Results Using two-dimensional electrophoresis followed by MALDI-TOF MS and /or LC-MS/MS 20 protein spots representing 10 proteins were identified with significant differences in abundance when stored at different temperatures. Our results, in agreement with various authors, indicate that during storage for a short period (13 days) at four different temperatures plasma proteins were more affected by degradation processes at +4°C compared to the other temperatures analysed. However, we founded that numerous protein spots (vitamin D binding protein, alpha-1-antitrypsin, serotransferrin, apoplipoprotein A-I, apolipoprotein E, haptoglobin and complement factor B) decrease in abundance with increasing temperature up to 4°C, but at room temperature their intensity mean values are similar to those of time zero and -80°C. We hypothesize that these proteins are labile at 4°C, but at the same time they are stable at room temperature (20-25°C). Furthermore we have grouped the proteins based on their different sensitivity to the storage temperature. Spots of serum albumin, fibrinogen gamma chain and haptoglobin are more resistant to the higher temperatures tested, as they have undergone changes in abundance only at room temperature; conversely, other spots of serum albumin, fibrinogen beta chain and serotransferrin are more labile as they have undergone changes in abundance at all temperatures except at -80°C. Conclusions Although there are many studies concerning protein stability of clinical samples during storage these findings may help to provide a better understanding of the changes of proteins induced by storage temperature. PMID:23518135

[Scrotal temperature in 258 healthy men, randomly selected from a population of men aged 18 to 23 years old. Statistical analysis, epidemiologic observations, and measurement of the testicular diameters].

PubMed

Valeri, A; Mianné, D; Merouze, F; Bujan, L; Altobelli, A; Masson, J

1993-06-01

Scrotal hyperthermia can induce certain alterations in spermatogenesis. The basal scrotal temperature used to define hyperthermia is usually 33 degrees C. However, no study, conducted according to a strict methodology has validated this mean measurement. We therefore randomly selected 258 men between the ages of 18 and 23 years from a population of 2,000 young French men seen at the National Service Selection Centre in order to measure the scrotal temperature over each testis and in the median raphe in order to determine the mean and median values for these temperatures. For a mean room temperature of 23 +/- 0.5 degrees C with a range of 18 to 31 degrees C, the mean right and left scrotal temperature was 34.2 +/- 0.1 degree C and the mean medioscrotal temperature was 34.4 +/- 0.1 degree C. Scrotal temperature was very significantly correlated to room temperature and its variations. It was therefore impossible to define a normal value for scrotal temperature. Only measurement of scrotal temperature at neutral room temperature, between 21 and 25 degrees C, is able to provide a reference value for scrotal temperature. In this study, the mean scrotal temperature under these conditions was 34.4 +/- 0.2 degree C, i.e. 2.5 degrees C less than body temperature. In the 12.9% of cases with left varicocele, left scrotal temperature was significantly higher than in the absence of varicocele and was also higher than right Scrotal temperature. The authors also determined the dimensions of the testes.(ABSTRACT TRUNCATED AT 250 WORDS)

Field study on occupant comfort and the office thermal environment in rooms with displacement ventilation.

PubMed

Melikov, A; Pitchurov, G; Naydenov, K; Langkilde, G

2005-06-01

A field survey of occupants' response to the indoor environment in 10 office buildings with displacement ventilation was performed. The response of 227 occupants was analyzed. About 24% of the occupants in the survey complained that they were daily bothered by draught, mainly at the lower leg. Vertical air temperature difference measured between head and feet levels was less than 3 degrees C at all workplaces visited. Combined local discomfort because of draught and vertical temperature difference does not seem to be a serious problem in rooms with displacement ventilation. Almost one half (49%) of the occupants reported that they were daily bothered by an uncomfortable room temperature. Forty-eight per cent of the occupants were not satisfied with the air quality. The PMV and the Draught Rating indices as well as the specifications for local discomfort because of the separate impact of draught and vertical temperature difference, as defined in the present standards, are relevant for the design of a thermal environment in rooms with displacement ventilation and for its assessment in practice. Increasing the supply air temperature in order to counteract draught discomfort is a measure that should be considered carefully; even if the desired stratification of pollution in the occupied zone is preserved, an increase of the inhaled air temperature may have a negative effect on perceived air quality.

A Comparison Study: The New Extended Shelf Life Isopropyl Ester PMR Technology versus The Traditional Methyl Ester PMR Approach

NASA Technical Reports Server (NTRS)

Alston, William B.; Scheiman, Daniel A.; Sivko, Gloria S.

2005-01-01

Polymerization of Monomeric Reactants (PMR) monomer solutions and carbon cloth prepregs of PMR II-50 and VCAP-75 were prepared using both the traditional limited shelf life methanol based PMR approach and a novel extended shelf life isopropanol based PMR approach. The methyl ester and isopropyl ester based PMR monomer solutions and PMR prepregs were aged for up to four years at freezer and room temperatures. The aging products formed were monitored using high pressure liquid chromatography (HPLC). The composite processing flow characteristics and volatile contents of the aged prepregs were also correlated versus room temperature storage time. Composite processing cycles were developed and six ply cloth laminates were fabricated with prepregs after various extended room temperature storage times. The composites were then evaluated for glass transition temperature (Tg), thermal decomposition temperature (Td), initial flexural strength (FS) and modulus (FM), long term (1000 hours at 316 C) thermal oxidative stability (TOS), and retention of FS and FM after 1000 hours aging at 316 C. The results for each ester system were comparable. Freezer storage was found to prevent the formation of aging products for both ester systems. Room temperature storage of the novel isopropyl ester system increased PMR monomer solution and PMR prepreg shelf life by at least an order of magnitude while maintaining composite properties.

Charge carrier recombination channels in the low-temperature phase of organic-inorganic lead halide perovskite thin films

NASA Astrophysics Data System (ADS)

Wehrenfennig, Christian; Liu, Mingzhen; Snaith, Henry J.; Johnston, Michael B.; Herz, Laura M.

2014-08-01

The optoelectronic properties of the mixed hybrid lead halide perovskite CH3NH3PbI3-xClx have been subject to numerous recent studies related to its extraordinary capabilities as an absorber material in thin film solar cells. While the greatest part of the current research concentrates on the behavior of the perovskite at room temperature, the observed influence of phonon-coupling and excitonic effects on charge carrier dynamics suggests that low-temperature phenomena can give valuable additional insights into the underlying physics. Here, we present a temperature-dependent study of optical absorption and photoluminescence (PL) emission of vapor-deposited CH3NH3PbI3-xClx exploring the nature of recombination channels in the room- and the low-temperature phase of the material. On cooling, we identify an up-shift of the absorption onset by about 0.1 eV at about 100 K, which is likely to correspond to the known tetragonal-to-orthorhombic transition of the pure halide CH3NH3PbI3. With further decreasing temperature, a second PL emission peak emerges in addition to the peak from the room-temperature phase. The transition on heating is found to occur at about 140 K, i.e., revealing significant hysteresis in the system. While PL decay lifetimes are found to be independent of temperature above the transition, significantly accelerated recombination is observed in the low-temperature phase. Our data suggest that small inclusions of domains adopting the room-temperature phase are responsible for this behavior rather than a spontaneous increase in the intrinsic rate constants. These observations show that even sparse lower-energy sites can have a strong impact on material performance, acting as charge recombination centres that may detrimentally affect photovoltaic performance but that may also prove useful for optoelectronic applications such as lasing by enhancing population inversion.

Tungsten Inert Gas and Friction Stir Welding Characteristics of 4-mm-Thick 2219-T87 Plates at Room Temperature and -196 °C

NASA Astrophysics Data System (ADS)

Lei, Xuefeng; Deng, Ying; Yin, Zhimin; Xu, Guofu

2014-06-01

2219-T87 aluminum alloy is widely used for fabricating liquid rocket propellant storage tank, due to its admirable cryogenic property. Welding is the dominant joining method in the manufacturing process of aerospace components. In this study, the tungsten inert gas welding and friction stir welding (FSW) characteristics of 4-mm-thick 2219-T87 alloy plate at room temperature (25 °C) and deep cryogenic temperature (-196 °C) were investigated by property measurements and microscopy methods. The studied 2219 base alloy exhibits a low strength plane anisotropy and excellent room temperature and cryogenic mechanical properties. The ultimate tensile strength values of TIG and FSW welding joints can reach 265 and 353 MPa at room temperature, and 342 and 438 MPa at -196 °C, respectively. The base metal consists of elongated deformed grains and many nano-scaled θ (Al2Cu) aging precipitates. Fusion zone and heat-affected zone (HAZ) of the TIG joint are characterized by coarsening dendritic grains and equiaxed recrystallized grains, respectively. The FSW-welded joint consists of the weld nugget zone, thermo-mechanically affected zone (TMAZ), and HAZ. In the weld nugget zone, a micro-scaled sub-grain structure is the main microstructure characteristic. The TMAZ and HAZ are both characterized by coarsened aging precipitates and elongated deformed grains. The excellent FSW welding properties are attributed to the preservation of the working structures and homogenous chemical compositions.

Frequency spectrum of tantalum at temperatures of 293-2300 K

NASA Astrophysics Data System (ADS)

Semenov, V. A.; Kozlov, Zh. A.; Krachun, L.; Mateescu, G.; Morozov, V. M.; Oprea, A. I.; Oprea, K.; Puchkov, A. V.

2010-05-01

The temperature dependence of the frequency spectrum of tantalum in the temperature range from room temperature to 2300 K has been studied for the first time using inelastic slow-neutron scattering. The inelastic slow-neutron scattering spectra have been measured at different temperatures on a DIN-2PI time-of-flight spectrometer installed at the IBR-2 nuclear reactor (Joint Institute for Nuclear Research, Dubna, Russia) with the use of a TS3000K high-temperature thermostat. From the measured spectra, the frequency spectra of the tantalum crystal lattice have been determined at temperatures of 293, 1584, and 2300 K by the iteration method. As the temperature increases, the frequency spectrum, on the whole, is softened and the specific features manifested themselves at room temperature are smoothed. The variations observed have been explained by the increase in the role of the effects of vibration anharmonism at high temperatures.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Luňáček, J., E-mail: jiri.lunacek@vsb.cz

The present paper is devoted to detailed study of the magnetically separable sorbents based on a cerium dioxide/iron oxide composite annealed at temperatures T{sub a} = 773 K, 873 K, and 973 K. The X-ray diffraction and high resolution transmission electron microscopy are used to determine the phase composition and microstructure morphology. Mössbauer spectroscopy at room (300 K) and low (5 K) temperatures has contributed to more exact identification of iron oxides and their transformations Fe{sub 3}O{sub 4} → γ-Fe{sub 2}O{sub 3} (ε-Fe{sub 2}O{sub 3}) → α-Fe{sub 2}O{sub 3} in dependence on calcination temperature. Different iron oxide phase compositions andmore » grain size distributions influence the magnetic characteristics determined from the room- and low-temperature hysteresis loop measurements. The results are supported by zero-field-cooled and field-cooled magnetization measurements allowing a quantitative estimation of the grain size distribution and its effect on the iron oxide transformations. - Highlights: •Magnetically separable sorbents based on a CeO{sub 2}/Fe{sub 2}O{sub 3} composite were investigated. •Microstructure of sorbents was determined by XRD, TEM and Mössbauer spectroscopy. •Magnetic properties were studied by hysteresis loops at room- and low-temperatures. •Phase transitions of iron oxides with increasing annealing temperature are observed.« less

Growth and Etch Rate Study of Low Temperature Anodic Silicon Dioxide Thin Films

PubMed Central

Ashok, Akarapu; Pal, Prem

2014-01-01

Silicon dioxide (SiO2) thin films are most commonly used insulating films in the fabrication of silicon-based integrated circuits (ICs) and microelectromechanical systems (MEMS). Several techniques with different processing environments have been investigated to deposit silicon dioxide films at temperatures down to room temperature. Anodic oxidation of silicon is one of the low temperature processes to grow oxide films even below room temperature. In the present work, uniform silicon dioxide thin films are grown at room temperature by using anodic oxidation technique. Oxide films are synthesized in potentiostatic and potentiodynamic regimes at large applied voltages in order to investigate the effect of voltage, mechanical stirring of electrolyte, current density and the water percentage on growth rate, and the different properties of as-grown oxide films. Ellipsometry, FTIR, and SEM are employed to investigate various properties of the oxide films. A 5.25 Å/V growth rate is achieved in potentiostatic mode. In the case of potentiodynamic mode, 160 nm thickness is attained at 300 V. The oxide films developed in both modes are slightly silicon rich, uniform, and less porous. The present study is intended to inspect various properties which are considered for applications in MEMS and Microelectronics. PMID:24672287

The effects of heated and room-temperature abdominal lavage solutions on core body temperature in dogs undergoing celiotomy.

PubMed

Nawrocki, Michael A; McLaughlin, Ron; Hendrix, P K

2005-01-01

To document the magnitude of temperature elevation obtained with heated lavage solutions during abdominal lavage, 18 dogs were lavaged with sterile isotonic saline intraoperatively (i.e., during a celiotomy). In nine dogs, room-temperature saline was used. In the remaining nine dogs, saline heated to 43+/-2 degrees C (110+/-4 degrees F) was used. Esophageal, rectal, and tympanic temperatures were recorded every 60 seconds for 15 minutes after initiation of the lavage. Temperature levels decreased in dogs lavaged with room-temperature saline. Temperature levels increased significantly in dogs lavaged with heated saline after 2 to 6 minutes of lavage, and temperatures continued to increase throughout the 15-minute lavage period.

Use of infrared thermography to assess the influence of high environmental temperature on rabbits.

PubMed

de Lima, V; Piles, M; Rafel, O; López-Béjar, M; Ramón, J; Velarde, A; Dalmau, A

2013-10-01

The aim of this work was to ascertain if infrared thermography (IRT) can be used on rabbits to assess differences in surface body temperature when they are subjected to two different environmental temperatures outside the comfort zone. Rabbits housed in room A were maintained at a temperature of below 30°C and rabbits in room B at a temperature of above 32°C for a year. Faeces were collected six times during the year to assess stress by means of faecal cortisol metabolites (FCM). The assessment of IRT was carried out to assess maximum and minimum temperatures on the eyes, nose and ears. FCM concentration was higher in room B than A, to confirm that stress conditions were higher in room B. Significant differences in IRT were found between the animals housed in both rooms. It was observed that it was more difficult for animals from room B to maintain a regular heat loss. Although all the body zones used to assess temperature with IRT gave statistical differences, the correlations found between the eyes, nose and ears were moderate, suggesting that they were giving different information. In addition, differences up to 3.36°C were found in the eye temperature of rabbits housed in the same room, with a clear effect of their position in relation to extractors and heating equipments. Therefore, IRT could be a good tool to assess heat stress in animals housed on typical rabbit farm buildings, giving a measure of how the animal is perceiving a combination of humidity, temperature and ventilation. Some face areas were better for analysing images. Minimum temperature on eyes and temperatures on nose are suggested to assess heat losses and critical areas of the farm for heat stress in rabbits. Copyright © 2013 Elsevier Ltd. All rights reserved.

Energy transfer simulation for radiantly heated and cooled enclosures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chapman, K.S.; Zhang, P.

1996-11-01

This paper presents the development of a three-dimensional mathematical model to compute heat transfer within a radiantly heated or cooled room, which then calculates the mass-averaged room air temperature and the wall surface temperature distributions. The radiation formulation used in the model accommodates arbitrary placement of walls and objects within the room. The convection model utilizes Nusselt number correlations published in the open literature. The complete energy transfer model is validated by comparing calculated room temperatures to temperatures measured in a radiantly heated room. This three-dimensional model may be applied to a building to assist the heating/cooling system design engineermore » in sizing a radiant heating/cooling system. By coupling this model with a thermal comfort model, the comfort levels throughout the room can be easily and efficiently mapped for a given radiant heater/cooler location. In addition, obstacles such as airplanes, trucks, furniture, and partitions can be easily incorporated to determine their effect on the radiant heating system performance.« less

Room-temperature wide-range luminescence and structural, optical, and electrical properties of SILAR deposited Cu-Zn-S nano-structured thin films

NASA Astrophysics Data System (ADS)

Jose, Edwin; Kumar, M. C. Santhosh

2016-09-01

We report the deposition of nanostructured Cu-Zn-S composite thin films by Successive Ionic Layer Adsorption and Reaction (SILAR) method on glass substrates at room temperature. The structural, morphological, optical, photoluminescence and electrical properties of Cu-Zn-S thin films are investigated. The results of X-ray diffraction (XRD) and Raman spectroscopy studies indicate that the films exhibit a ternary Cu-Zn-S structure rather than the Cu xS and ZnS binary composite. Scanning electron microscope (SEM) studies show that the Cu-Zn-S films are covered well over glass substrates. The optical band gap energies of the Cu-Zn-S films are calculated using UV-visible absorption measurements, which are found in the range of 2.2 to 2.32 eV. The room temperature photoluminescence studies show a wide range of emissions from 410 nm to 565 nm. These emissions are mainly due to defects and vacancies in the composite system. The electrical studies using Hall effect measurements show that the Cu-Zn-S films are having p-type conductivity.

Room-Temperature Processing of TiOx Electron Transporting Layer for Perovskite Solar Cells.

PubMed

Deng, Xiaoyu; Wilkes, George C; Chen, Alexander Z; Prasad, Narasimha S; Gupta, Mool C; Choi, Joshua J

2017-07-20

In order to realize high-throughput roll-to-roll manufacturing of flexible perovskite solar cells, low-temperature processing of all device components must be realized. However, the most commonly used electron transporting layer in high-performance perovskite solar cells is based on TiO 2 thin films processed at high temperature (>450 °C). Here, we demonstrate room temperature solution processing of the TiO x layer that performs as well as the high temperature TiO 2 layer in perovskite solar cells, as evidenced by a champion solar cell efficiency of 16.3%. Using optical spectroscopy, electrical measurements, and X-ray diffraction, we show that the room-temperature processed TiO x is amorphous with organic residues, and yet its optical and electrical properties are on par with the high-temperature TiO 2 . Flexible perovskite solar cells that employ a room-temperature TiO x layer with a power conversion efficiency of 14.3% are demonstrated.

Room-temperature photomagnetism in the spinel ferrite (Mn,Zn,Fe)3O4 as seen via soft x-ray magnetic circular dichroism

NASA Astrophysics Data System (ADS)

Bettinger, J. S.; Piamonteze, C.; Chopdekar, R. V.; Liberati, M.; Arenholz, E.; Suzuki, Y.

2009-10-01

We have used x-ray magnetic circular dichroism (XMCD) in conjunction with multiplet simulations to directly probe the origin of photomagnetism in nanocrystalline (Mn,Zn,Fe)3O4 . A photomagnetic effect at room temperature has been observed in these films with HeNe illumination. We have verified an intervalence charge transfer among octahedral Fe cations to account for the increase in magnetization observed at and above room temperature in small magnetic fields. Using XMCD, we demonstrate that the dichroism of Fe in octahedral sites increases by 18% at room temperature, while the dichroism of Fe in tetrahedral sites does not change.

Room-temperature ferromagnetism observed in C-/N-/O-implanted MgO single crystals

NASA Astrophysics Data System (ADS)

Li, Qiang; Ye, Bonian; Hao, Yingping; Liu, Jiandang; Zhang, Jie; Zhang, Lijuan; Kong, Wei; Weng, Huimin; Ye, Bangjiao

2013-01-01

MgO single crystals were implanted with 70 keV C/N/O ions at room temperature with respective doses of 2 × 1016 and 2 × 1017 ions/cm2. All samples with high-dose implantation showed room temperature hysteresis in magnetization loops. Magnetization and slow positron annihilation measurements confirmed that room temperature ferromagnetism in O-implanted samples was attributed to the presence of Mg vacancies. Furthermore, the introduction of C or N played more effective role in ferromagnetic performance than Mg vacancies. Moreover, the magnetic moment possibly occurred from the localized wave function of unpaired electrons and the exchange interaction formed a long-range magnetic order.

Room Temperature ppb Level Chlorine Gas Sensor Based on Copper (II) 1, 4, 8, 11, 15, 18, 22, 25-octabutoxy-29 H, 31 H-phthalocyanine Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bedi, R. K.; Saini, Rajan; Mahajan, Aman

2010-12-01

Spin coating technique has been used to fabricate room temperature chlorine gas sensor based on copper (II) 1, 4, 8, 11, 15, 18, 22, 25-octabutoxy-29 H, 31 H-phthalocyanine (CuPc(OBu){sub 8}) films. Gas sensor shows a response of 185% to few parts per billion level of Cl{sub 2} gas with response time of 9.5 minutes at room temperature. The interactions between sensor and analytes followed first order kinetics with rate constant 0.01{<=}k{<=}0.02. The chemiresistive sensor showed very good stability at room temperature over a long period of time.

Porous Si nanowires for highly selective room-temperature NO2 gas sensing

NASA Astrophysics Data System (ADS)

Kwon, Yong Jung; Mirzaei, Ali; Gil Na, Han; Kang, Sung Yong; Choi, Myung Sik; Bang, Jae Hoon; Oum, Wansik; Kim, Sang Sub; Kim, Hyoun Woo

2018-07-01

We report the room-temperature sensing characteristics of Si nanowires (NWs) fabricated from p-Si wafers by a metal-assisted chemical etching method, which is a facile and low-cost method. X-ray diffraction was used to the the study crystallinity and phase formation of Si NWs, and product morphology was examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). After confirmation of Si NW formation via the SEM and TEM micrographs, sensing tests were carried out at room temperature, and it was found that the Si NW sensor prepared from Si wafers with a resistivity of 0.001–0.003 Ω.cm had the highest response to NO2 gas (Rg/Ra = 1.86 for 50 ppm NO2), with a fast response (15 s) and recovery (30 s) time. Furthermore, the sensor responses to SO2, toluene, benzene, H2, and ethanol were nearly negligible, demonstrating the excellent selectivity to NO2 gas. The gas-sensing mechanism is discussed in detail. The present sensor can operate at room temperature, and is compatible with the microelectronic fabrication process, demonstrating its promise for next-generation Si-based electronics fused with functional chemical sensors.

Porous Si nanowires for highly selective room-temperature NO2 gas sensing.

PubMed

Kwon, Yong Jung; Mirzaei, Ali; Na, Han Gil; Kang, Sung Yong; Choi, Myung Sik; Bang, Jae Hoon; Oum, Wansik; Kim, Sang Sub; Kim, Hyoun Woo

2018-07-20

We report the room-temperature sensing characteristics of Si nanowires (NWs) fabricated from p-Si wafers by a metal-assisted chemical etching method, which is a facile and low-cost method. X-ray diffraction was used to the the study crystallinity and phase formation of Si NWs, and product morphology was examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). After confirmation of Si NW formation via the SEM and TEM micrographs, sensing tests were carried out at room temperature, and it was found that the Si NW sensor prepared from Si wafers with a resistivity of 0.001-0.003 Ω.cm had the highest response to NO 2 gas (R g /R a  = 1.86 for 50 ppm NO 2 ), with a fast response (15 s) and recovery (30 s) time. Furthermore, the sensor responses to SO 2 , toluene, benzene, H 2 , and ethanol were nearly negligible, demonstrating the excellent selectivity to NO 2 gas. The gas-sensing mechanism is discussed in detail. The present sensor can operate at room temperature, and is compatible with the microelectronic fabrication process, demonstrating its promise for next-generation Si-based electronics fused with functional chemical sensors.

A highly reversible room-temperature sodium metal anode

DOE PAGES

Seh, Zhi Wei; Sun, Jie; Sun, Yongming; ...

2015-11-02

Owing to its low cost and high natural abundance, sodium metal is among the most promising anode materials for energy storage technologies beyond lithium ion batteries. However, room-temperature sodium metal anodes suffer from poor reversibility during long-term plating and stripping, mainly due to formation of nonuniform solid electrolyte interphase as well as dendritic growth of sodium metal. Herein we report for the first time that a simple liquid electrolyte, sodium hexafluorophosphate in glymes (mono-, di-, and tetraglyme), can enable highly reversible and nondendritic plating–stripping of sodium metal anodes at room temperature. High average Coulombic efficiencies of 99.9% were achieved overmore » 300 plating–stripping cycles at 0.5 mA cm –2. In this study, the long-term reversibility was found to arise from the formation of a uniform, inorganic solid electrolyte interphase made of sodium oxide and sodium fluoride, which is highly impermeable to electrolyte solvent and conducive to nondendritic growth. As a proof of concept, we also demonstrate a room-temperature sodium–sulfur battery using this class of electrolytes, paving the way for the development of next-generation, sodium-based energy storage technologies.« less

Room Temperature Hard Radiation Detectors Based on Solid State Compound Semiconductors: An Overview

NASA Astrophysics Data System (ADS)

Mirzaei, Ali; Huh, Jeung-Soo; Kim, Sang Sub; Kim, Hyoun Woo

2018-05-01

Si and Ge single crystals are the most common semiconductor radiation detectors. However, they need to work at cryogenic temperatures to decrease their noise levels. In contrast, compound semiconductors can be operated at room temperature due to their ability to grow compound materials with tunable densities, band gaps and atomic numbers. Highly efficient room temperature hard radiation detectors can be utilized in biomedical diagnostics, nuclear safety and homeland security applications. In this review, we discuss room temperature compound semiconductors. Since the field of radiation detection is broad and a discussion of all compound materials for radiation sensing is impossible, we discuss the most important materials for the detection of hard radiation with a focus on binary heavy metal semiconductors and ternary and quaternary chalcogenide compounds.

Room-Temperature Determination of Two-Dimensional Electron Gas Concentration and Mobility in Heterostructures

NASA Technical Reports Server (NTRS)

Schacham, S. E.; Mena, R. A.; Haugland, E. J.; Alterovitz, S. A.

1993-01-01

A technique for determination of room-temperature two-dimensional electron gas (2DEG) concentration and mobility in heterostructures is presented. Using simultaneous fits of the longitudinal and transverse voltages as a function of applied magnetic field, we were able to separate the parameters associated with the 2DEG from those of the parallel layer. Comparison with the Shubnikov-de Haas data derived from measurements at liquid helium temperatures proves that the analysis of the room-temperature data provides an excellent estimate of the 2DEG concentration. In addition we were able to obtain for the first time the room-temperature mobility of the 2DEG, an important parameter to device application. Both results are significantly different from those derived from conventional Hall analysis.

Fatigue and fracture mechanical behavior for Chinese A508-3 steel at room temperature

NASA Astrophysics Data System (ADS)

Shi, K. K.; Xie, H.; Zheng, B.; Fu, X. L.

2018-06-01

Material, A508-3 steel, has been used in nuclear reactor vessels. In the present study, fatigue and fracture mechanical behavior of Chinese A5083 steel at room temperature are studied by mechanical material testing machine (MTS). Test data of material’s mechanical behavior including uniaxial tension, low cycle fatigue (LCF), threshold value of stress intensity factor (SIF) range, fatigue crack growth (FCG), and fracture toughness is generated and given for further study. It is worth noting that the model in predicting FCG of material from LCF parameters is verified and discussed.

X-ray photoelectron spectroscopy study of the stability of Fomblin Z25 on the native oxide of aluminum

NASA Technical Reports Server (NTRS)

Herrera-Fierro, Pilar; Pepper, Stephen V.; Jones, William R.

1992-01-01

Thin films of Fomblin Z25, a perfluoropolyalkylether lubricant, were vapor deposited onto clean, oxidized aluminum, and onto sapphire surfaces, and their behavior at different temperatures was studied using X-ray photoelectron spectroscopy and temperature desorption spectroscopy (TDS). The interfacial fluid molecules decompose on the native oxide at room temperature, and continue to decompose at elevated temperatures, as previous studies had shown to occur on the clean metal. TDS indicated that different degradation mechanisms were operative for clean and oxidized aluminum. On sapphire substrates, no reaction was observed at room temperature. The native oxide of aluminum is neither passive nor protective towards Fomblin Z25. At higher temperatures (150 C), degradation of the polymer on sapphire produced a debris layer at the interface with a chemical composition similar to the one formed on aluminum oxide. Rubbing a Fomblin film on a single crystal sapphire also induced the decomposition of the lubricant in contact with the interface and the formation of a debris layer.

Deposition of silicon oxynitride films by low energy ion beam assisted nitridation at room temperature

NASA Astrophysics Data System (ADS)

Youroukov, S.; Kitova, S.; Danev, G.

2008-05-01

The possibility is studied of growing thin silicon oxynitride films by e-gun evaporation of SiO and SiO2 together with concurrent bombardment with low energy N2+ ions from a cyclotron resonance (ECR) source at room temperature of substrates. The degree of nitridation and oxidation of the films is investigated by means of X-ray spectroscopy. The optical characteristics of the films, their environmental stability and adhesion to different substrates are examined. The results obtained show than the films deposited are transparent. It is found that in the case of SiO evaporation with concurrent N2+ ion bombardment, reactive implantation of nitrogen within the films takes place at room temperature of the substrate with the formation of a new silicon oxynitride compound even at low ion energy (150-200 eV).

Thirty Years of Near Room Temperature Magnetic Cooling: Where we are Today and Future Prospects

DOE Office of Scientific and Technical Information (OSTI.GOV)

K.A. Gschneidner, Jr; V.K. Pecharsky'

2008-05-01

The seminal study by Brown in 1976 showed that it was possible to use the magnetocaloric effect to produce a substantial cooling effect near room temperature. About 15 years later Green et al. built a device which actually cooled a load other than the magnetocaloric material itself and the heat exchange fluid. The major breakthrough, however, occurred in 1997 when the Ames Laboratory/Astronautics proof-of-principle refrigerator showed that magnetic refrigeration was competitive with conventional gas compression cooling. Since then, over 25 magnetic cooling units have been built and tested throughout the world. The current status of near room temperature magnetic coolingmore » is reviewed, including a discussion of the major problems facing commercialization and potential solutions thereof. The future outlook for this revolutionary technology is discussed.« less

Reactions of butadiyne. 1: The reaction with hydrogen atoms

NASA Technical Reports Server (NTRS)

Schwanebeck, W.; Warnatz, J.

1984-01-01

The reaction of hydrogen (H) atoms with butadiene (C4H2) was studied at room temperature in a pressure range between w mbar and 10 mbar. The primary step was an addition of H to C4H2 which is in its high pressure range at p 1 mbar. Under these conditions the following addition of a second H atom lies in the transition region between low and high pressure range. Vibrationally excited C4H4 can be deactivated to form buten-(1)-yne-(3)(C4H4) or decomposes into two C2H2 molecules. The rate constant at room temperature for primary step is given. The second order rate constant for the consumption of buten-(1)-yne-(3) is an H atom excess at room temperature is given.

High-quality RNA extracted from biopsied samples dehydrated and stored dried at room temperature without chemical preservation for up to 3 months as evidenced by RT-PCR results.

PubMed

Sadler, Theodore R; Khodavirdi, Ani C

2015-07-01

Handling and maintenance of biological tissues for nucleic acid and/or protein analysis has long been a challenge because of the perceived instability of these molecules at room temperature if not preserved or processed. Structural damage and compromised integrity of aforementioned biomolecules subsequent to preservation have also posed difficulties in their use in research. The development of technologies employing nonfixative methods with the capability to store at room temperature have been of growing interest. Our previous publication exploring preservation of proteins by desiccation challenged the convention of their unstable nature. Herein, we report the results of quantitative and qualitative analyses of RNA from tissue samples that were desiccated and stored at room temperature for up to 3 months. Our results indicate that viable RNA can be obtained from dehydrated ex vivo tissue samples that have been stored at room temperature.

Structure determination of an integral membrane protein at room temperature from crystals in situ

DOE Office of Scientific and Technical Information (OSTI.GOV)

Axford, Danny; Foadi, James; Imperial College London, London SW7 2AZ

2015-05-14

The X-ray structure determination of an integral membrane protein using synchrotron diffraction data measured in situ at room temperature is demonstrated. The structure determination of an integral membrane protein using synchrotron X-ray diffraction data collected at room temperature directly in vapour-diffusion crystallization plates (in situ) is demonstrated. Exposing the crystals in situ eliminates manual sample handling and, since it is performed at room temperature, removes the complication of cryoprotection and potential structural anomalies induced by sample cryocooling. Essential to the method is the ability to limit radiation damage by recording a small amount of data per sample from many samplesmore » and subsequently assembling the resulting data sets using specialized software. The validity of this procedure is established by the structure determination of Haemophilus influenza TehA at 2.3 Å resolution. The method presented offers an effective protocol for the fast and efficient determination of membrane-protein structures at room temperature using third-generation synchrotron beamlines.« less

Is the boundary layer of an ionic liquid equally lubricating at higher temperature?

PubMed

Hjalmarsson, Nicklas; Atkin, Rob; Rutland, Mark W

2016-04-07

Atomic force microscopy has been used to study the effect of temperature on normal forces and friction for the room temperature ionic liquid (IL) ethylammonium nitrate (EAN), confined between mica and a silica colloid probe at 25 °C, 50 °C, and 80 °C. Force curves revealed a strong fluid dynamic influence at room temperature, which was greatly reduced at elevated temperatures due to the reduced liquid viscosity. A fluid dynamic analysis reveals that bulk viscosity is manifested at large separation but that EAN displays a nonzero slip, indicating a region of different viscosity near the surface. At high temperatures, the reduction in fluid dynamic force reveals step-like force curves, similar to those found at room temperature using much lower scan rates. The ionic liquid boundary layer remains adsorbed to the solid surface even at high temperature, which provides a mechanism for lubrication when fluid dynamic lubrication is strongly reduced. The friction data reveals a decrease in absolute friction force with increasing temperature, which is associated with increased thermal motion and reduced viscosity of the near surface layers but, consistent with the normal force data, boundary layer lubrication was unaffected. The implications for ILs as lubricants are discussed in terms of the behaviour of this well characterised system.

Stability of alemtuzumab solutions at room temperature.

PubMed

Goldspiel, Justin T; Goldspiel, Barry R; Grimes, George J; Yuan, Peng; Potti, Gopal

2013-03-01

The 24-hour stability of alemtuzumab solutions prepared at concentrations not included in the product label and stored in glass or polyolefin containers at room temperature was evaluated. Triplicate solutions of alemtuzumab (6.67, 40, and 120 μg/mL) in 0.9% sodium chloride were prepared in either glass bottles or polyolefin containers and stored at room temperature under normal fluorescent lighting conditions. The solutions were analyzed by a validated stability-indicating high-performance liquid chromatography (HPLC) assay at time zero and 8, 14, and 24 hours after preparation; solution pH values were measured and the containers visually inspected at all time points. Stability was defined as the retention of ≥90% of the initial alemtuzumab concentration. HPLC analysis indicated that the percentage of the initial alemtuzumab concentration retained was >90% for all solutions evaluated, with no significant changes over the study period. The most dilute alemtuzumab solution (6.67 μg/mL) showed some degradation (91% of the initial concentration retained at hour 24), whereas the retained concentration was >99% for all other preparations throughout the study period. Solution pH values varied by drug concentration but did not change significantly over 24 hours. No evidence of particle formation was detected in any solution by visual inspection at any time during the study. Solutions of alemtuzumab 6.67 μg/mL stored in glass bottles and solutions of 40 and 120 μg/mL stored in polyolefin containers were stable for at least 24 hours at room temperature.

Broad-gain (Δλ/λ0

PubMed

Fujita, Kazuue; Furuta, Shinichi; Dougakiuchi, Tatsuo; Sugiyama, Atsushi; Edamura, Tadataka; Yamanishi, Masamichi

2011-01-31

Broad-gain operation of λ~8.7 μm quantum cascade lasers based on dual-upper-state to multiple-lower-state transition design is reported. The devices exhibit surprisingly wide (~500 cm(-1)) electroluminescence spectra which are very insensitive to voltage and temperature changes above room temperature. With recourse to the temperature-insensitivity of electroluminescence spectra, the lasers demonstrate an extremely-weak temperature-dependence of laser performances: T0-value of 510 K, associated with a room temperature threshold current density of 2.6 kA/cm2. In addition, despite such wide gain spectra, room temperature, continuous wave operation of the laser with buried hetero structure is achieved.

Ultra-Low-Cost Room Temperature SiC Thin Films

NASA Technical Reports Server (NTRS)

Faur, Maria

1997-01-01

The research group at CSU has conducted theoretical and experimental research on 'Ultra-Low-Cost Room Temperature SiC Thin Films. The effectiveness of a ultra-low-cost room temperature thin film SiC growth technique on Silicon and Germanium substrates and structures with applications to space solar sells, ThermoPhotoVoltaic (TPV) cells and microelectronic and optoelectronic devices was investigated and the main result of this effort are summarized.

Negative differential resistance in GaN nanocrystals above room temperature.

PubMed

Chitara, Basant; Ivan Jebakumar, D S; Rao, C N R; Krupanidhi, S B

2009-10-07

Negative differential resistance (NDR) has been observed for the first time above room temperature in gallium nitride nanocrystals synthesized by a simple chemical route. Current-voltage characteristics have been used to investigate this effect through a metal-semiconductor-metal (M-S-M) configuration on SiO2. The NDR effect is reversible and reproducible through many cycles. The threshold voltage is approximately 7 V above room temperature.

Neutron absorbing room temperature vulcanizable silicone rubber compositions

DOEpatents

Zoch, Harold L.

1979-11-27

A neutron absorbing composition comprising a one-component room temperature vulcanizable silicone rubber composition or a two-component room temperature vulcanizable silicone rubber composition in which the composition contains from 25 to 300 parts by weight based on the base silanol or vinyl containing diorganopolysiloxane polymer of a boron compound or boron powder as the neutron absorbing ingredient. An especially useful boron compound in this application is boron carbide.

Novel Nanocomposite Structures as Active and Passive Barrier Materials

DTIC Science & Technology

2010-06-01

during the course of this ARO-funded project. The development of a novel polymer material based on a diol-functionalized room-temperature ionic liquid ...material based on a diol-functionalized room- temperature ionic liquid (RTIL) monomer led to fabrication of membranes, which were tested for their...stimulant vapor. Technical Report A polymerizable room-temperature ionic liquid (4, Figure 1) was chosen as the starting material for making poly(RTIL

Penicillium populations in dry-cured ham manufacturing plants.

PubMed

Battilani, Paola; Pietri, V Amedeo; Giorni, Paola; Formenti, Silvia; Bertuzzi, Terenzio; Toscani, Tania; Virgili, Roberta; Kozakiewicz, Zofia

2007-04-01

Seven ham manufacturing plants were sampled for 1 year to assess the mycoflora present in the air and on hams, with special attention given to potential mycotoxin producers. Temperature and relative humidity were recorded in the ripening rooms. Maturing rooms held hams from 2 to 3 through 6 to 7 ripening months, and aging rooms held hams for the following 6 to 7 months, until the 14-month ripening point, when they were ready for the market. Mean temperatures and relative humidities registered during the study were 14.9 degrees C and 62.4%, respectively, in maturing rooms and 16.3 degrees C and 57.6% in aging rooms. Aspergilli and penicillia, potential mycotoxin producers, were isolated in all the plants from the air and the ham. Aspergilli represented 5% of the isolates, while penicillia were largely dominant, with Penicillium nalgiovense being the most represented species (around 60% of the penicillia), followed by Penicillium nordicum, with 10 and 26% of the penicillia isolated, respectively, from the air or the ham. Ochratoxin A production ability, checked in vitro at 250C, was observed in 50% of the P. nordicum isolates obtained both from the air and the ham. Air and ham surface contamination by penicillia was greater in the ripening rooms, where higher temperatures were registered. A certain correlation was also observed between air and ham surface contamination. On the basis of this study, P. nordicum, the ochratoxin A producer that is notable on proteinaceous substrates, is normally present in ham manufacturing plants in Italy, even though not a dominant species. Further studies are necessary to clarify and ensure if dry-curing conditions minimize the potential risk of ochratoxin A formation in the product.

Development of Pasteuria penetrans in Meloidogyne javanica females as affected by constantly high vs fluctuating temperature in an in-vivo system.

PubMed

Darban, D A; Gowen, S R; Pembroke, B; Mahar, A N

2005-03-01

Growth room and glasshouse experiment was conducted to investigate the effect of constant and fluctuating temperatures on the development of Pasteuria penetrans a hyperparasite of root-knot nematodes. Tomato plants (Lycopersicon esculentum Mill) were inoculated with Meloidogyne javanica second-stage juveniles attached with endospores of P. penetrans and were grown in growth room at 26-29 degrees C and in glasshouse at 20-32 degrees C. The tomato plants were sampled from the growth room after 600 degree-days based on 17 degrees C/d, accumulating each day above a base temperature of 10 degrees C and from the glasshouse after 36 calendar days. Temperature affected the development of P. penetrans directly. The rate of development at constant temperature in growth room was faster than that in the glasshouse at fluctuating temperatures.

Development of Pasteuria penetrans in Meloidogyne javanica females as affected by constantly high vs fluctuating temperature in an in-vivo system

PubMed Central

Darban, D.A.; Gowen, S.R.; Pembroke, B.; Mahar, A.N.

2005-01-01

Growth room and glasshouse experiment was conducted to investigate the effect of constant and fluctuating temperatures on the development of Pasteuria penetrans a hyperparasite of root-knot nematodes. Tomato plants (Lycopersicon esculentum Mill) were inoculated with Meloidogyne javanica second-stage juveniles attached with endospores of P. penetrans and were grown in growth room at 26–29 °C and in glasshouse at 20–32 °C. The tomato plants were sampled from the growth room after 600 degree-days based on 17 °C/d, accumulating each day above a base temperature of 10 °C and from the glasshouse after 36 calendar days. Temperature affected the development of P. penetrans directly. The rate of development at constant temperature in growth room was faster than that in the glasshouse at fluctuating temperatures. PMID:15682497

Mercuric iodine room temperature gamma-ray detectors

NASA Technical Reports Server (NTRS)

Patt, Bradley E.; Markakis, Jeffrey M.; Gerrish, Vernon M.; Haymes, Robert C.; Trombka, Jacob I.

1990-01-01

high resolution mercuric iodide room temperature gamma-ray detectors have excellent potential as an essential component of space instruments to be used for high energy astrophysics. Mercuric iodide detectors are being developed both as photodetectors used in combination with scintillation crystals to detect gamma-rays, and as direct gamma-ray detectors. These detectors are highly radiation damage resistant. The list of applications includes gamma-ray burst detection, gamma-ray line astronomy, solar flare studies, and elemental analysis.

Effects of reduced nocturnal temperature on pig performance and energy consumption in swine nursery rooms.

PubMed

Johnston, L J; Brumm, M C; Moeller, S J; Pohl, S; Shannon, M C; Thaler, R C

2013-07-01

The objective of this investigation was to determine the effect of a reduced nocturnal temperature (RNT) regimen on performance of weaned pigs and energy consumption during the nursery phase of production. The age of weaned pigs assigned to experiments ranged from 16 to 22 d. In Exp. 1, 3 stations conducted 2 trials under a common protocol that provided data from 6 control rooms (CON; 820 pigs) and 6 RNT rooms (818 pigs). Two mirror-image nursery rooms were used at each station. Temperature in the CON room was set to 30°C for the first 7 d, then reduced by 2°C per week through the remainder of the experiment. Room temperature settings were held constant throughout the day and night. The temperature setting in the RNT room was the same as CON during the first 7 d, but beginning on the night of d 7, the room temperature setting was reduced 6°C from the daytime temperature from 1900 to 0700 h. The use of heating fuel and electricity were measured weekly in each room. Overall, ADG (0.43 kg), ADFI (0.62 kg), and G:F (0.69) were identical for CON and RNT rooms. Consumption of heating fuel [9,658 vs. 7,958 British thermal units (Btu)·pig(-1)·d(-1)] and electricity (0.138 vs. 0.125 kilowatt-hour (kWh)·pig(-1)·d(-1)] were not statistically different for CON and RNT rooms, respectively. In Exp. 2, 4 stations conducted at least 2 trials that provided data from 9 CON rooms (2,122 pigs) and 10 RNT rooms (2,176 pigs). Experimental treatments and protocols were the same as Exp. 1, except that the RNT regimen was imposed on the night of d 5 and the targeted nighttime temperature reduction was 8.3°C. Neither final pig BW (21.8 vs. 21.5 kg; SE = 0.64), ADG (0.45 vs. 0.44 kg; SE = 0.016), ADFI (0.61 vs. 0.60 kg; SE = 0.019), nor G:F (0.75 vs. 0.75; SE = 0.012) were different for pigs housed in CON or RNT rooms, respectively. Consumption of heating fuel and electricity was consistently reduced in RNT rooms for all 4 stations. Consumption of heating fuel (10,019 vs. 7,061 Btu·pig(-1)·d(-1); SE = 1,467) and electricity (0.026 vs. 0.021 kWh·pig-1·d-1; SE = 0.004) were lower (P < 0.05) in the RNT rooms compared with CON rooms. This represents a 30% reduction in heating fuel use and a 20% reduction in electrical use with no differences in pig growth performance or health. From these experiments, we conclude that imposing a RNT regimen from 1900 to 0700 h is effective in reducing energy costs in the nursery without compromising pig performance, which will reduce production costs and decrease emissions of greenhouse gases.

Heterogeneity in a room-temperature ionic liquid: persistent local environments and the red-edge effect.

PubMed

Hu, Zhonghan; Margulis, Claudio J

2006-01-24

In this work, we investigate the slow dynamics of 1-butyl-3-methylimidazolium hexafluorophosphate, a very popular room-temperature ionic solvent. Our study predicts the existence of heterogeneity in the liquid and shows that this heterogeneity is the underlying microscopic cause for the recently reported "red-edge effect" (REE) observed in the study of fluorescence of the organic probe 2-amino-7-nitrofluorene. This theoretical work explains in microscopic terms the relation between REE and dynamic heterogeneity in a room-temperature ionic liquid (IL). The REE is typical of micellar or colloidal systems, which are characterized by microscopic environments that are structurally very different. In contrast, in the case of this room-temperature IL, the REE occurs because of the long period during which molecules are trapped in quasistatic local solvent cages. This trapping time, which is longer than the lifetime of the excited-state probe, together with the inability of the surroundings to adiabatically relax, induces a set of site-specific spectroscopic responses. Subensembles of fluorescent molecules associated with particular local environments absorb and emit at different frequencies. We describe in detail the absorption wavelength-dependent emission spectra of 2-amino-7-nitrofluorene and show that this dependence on lambda(ex) is characteristic of the IL and, as is to be expected, is absent in the case of a normal solvent such as methanol.

Room temperature ferromagnetism in transition metal-doped black phosphorous

NASA Astrophysics Data System (ADS)

Jiang, Xiaohong; Zhang, Xinwei; Xiong, Fang; Hua, Zhenghe; Wang, Zhihe; Yang, Shaoguang

2018-05-01

High pressure high temperature synthesis of transition metal (TM = V, Cr, Mn, Fe, Co, Ni, and Cu) doped black phosphorus (BP) was performed. Room temperature ferromagnetism was observed in Cr and Mn doped BP samples. X-ray diffraction and Raman measurements revealed pure phase BP without any impurity. Transport measurements showed us semiconducting character in 5 at. % doped BP samples Cr5%P95% and Mn5%P95%. The magnetoresistance (MR) studies presented positive MR in the relatively high temperature range and negative MR in the low temperature range. Compared to that of pure BP, the maximum MR was enhanced in Cr5%P95%. However, paramagnetism was observed in V, Fe, Co, Ni, and Cu doped BP samples.

Hyperfine Fields of 181Ta in UFe4Al8

NASA Astrophysics Data System (ADS)

Marques, J. G.; Barradas, N. P.; Alves, E.; Ramos, A. R.; Gonçalves, A. P.; da Silva, M. F.; Soares, J. C.

2001-11-01

The γ γ Perturbed Angular Correlation technique was used to study the hyperfine interaction of 181Ta at the Hf site(s) in UFe4Al8 at room temperature and 12 K. The data at room temperature are well described by two electric field gradients, while at low temperature two combined hyperfine interactions have to be considered, one with the magnetic hyperfine field collinear with the c-axis and another with the magnetic hyperfine field in the basal plane. The results are compared with previous Mössbauer and neutron diffraction experiments and the lattice site of Hf is discussed.

InN thin-film transistors fabricated on polymer sheets using pulsed sputtering deposition at room temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lye, Khe Shin; Kobayashi, Atsushi; Ueno, Kohei

Indium nitride (InN) is potentially suitable for the fabrication of high performance thin-film transistors (TFTs) because of its high electron mobility and peak electron velocity. However, InN is usually grown using a high temperature growth process, which is incompatible with large-area and lightweight TFT substrates. In this study, we report on the room temperature growth of InN films on flexible polyimide sheets using pulsed sputtering deposition. In addition, we report on the fabrication of InN-based TFTs on flexible polyimide sheets and the operation of these devices.

Practical and efficient magnetic heat pump

NASA Technical Reports Server (NTRS)

Brown, G. V.

1978-01-01

Method for pumping heat magnetically at room temperature is more economical than existing refrigeration systems. Method uses natural magneto-thermal effect of gadolinium metal to establish temperature gradient across length of tube. Regenerative cyclic process in which gadolinium sample is magnetized and gives off heat at one end of tube, and then is demagnetized at other end to absorb heat has established temperature gradients of 144 degrees F in experiments near room temperature. Other materials with large magnetothermal effects can be used below room temperature. Possible commercial applications include freeze-drying and food processing, cold storage, and heating and cooling of buildings, plants, and ships.

Stability of echogenic liposomes as a blood pool ultrasound contrast agent in a physiologic flow phantom.

PubMed

Radhakrishnan, Kirthi; Haworth, Kevin J; Huang, Shao-Ling; Klegerman, Melvin E; McPherson, David D; Holland, Christy K

2012-11-01

Echogenic liposomes (ELIP) are multifunctional ultrasound contrast agents (UCAs) with a lipid shell encapsulating both air and an aqueous core. ELIP are being developed for molecular imaging and image-guided therapeutic delivery. Stability of the echogenicity of ELIP in physiologic conditions is crucial to their successful translation to clinical use. In this study, we determined the effects of the surrounding media's dissolved air concentration, temperature transition and hydrodynamic pressure on the echogenicity of a chemically modified formulation of ELIP to promote stability and echogenicity. ELIP samples were diluted in porcine plasma or whole blood and pumped through a pulsatile flow system with adjustable hydrodynamic pressures and temperature. B-mode images were acquired using a clinical diagnostic scanner every 5 s for a total duration of 75 s. Echogenicity in porcine plasma was assessed as a function of total dissolved gas saturation. ELIP were added to plasma at room temperature (22 °C) or body temperature (37 °C) and pumped through a system maintained at 22 °C or 37 °C to study the effect of temperature transitions on ELIP echogenicity. Echogenicity at normotensive (120/80 mmHg) and hypertensive pressures (145/90 mmHg) was measured. ELIP were echogenic in plasma and whole blood at body temperature under normotensive to hypertensive pressures. Warming of samples from room temperature to body temperature did not alter echogenicity. However, in plasma cooled rapidly from body temperature to room temperature or in degassed plasma, ELIP lost echogenicity within 20 s at 120/80 mmHg. The stability of echogenicity of a modified ELIP formulation was determined in vitro at body temperature, physiologic gas concentration and throughout the physiologic pressure range. However, proper care should be taken to ensure that ELIP are not cooled rapidly from body temperature to room temperature as they will lose their echogenic properties. Further in vivo investigations will be needed to evaluate the optimal usage of ELIP as blood pool contrast agents. Copyright © 2012 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Low-temperature operation of a Buck DC/DC converter

NASA Technical Reports Server (NTRS)

Ray, Biswajit; Gerber, Scott S.; Patterson, Richard L.; Myers, Ira T.

1995-01-01

Low-temperature (77 K) operation of a 42/28 V, 175 W, 50 kHz PWM Buck DC/DC converter designed with commercially available components is reported. Overall, the converter losses decreased at 77 K compared to room temperature operation. A full-load efficiency of 97 percent was recorded at liquid-nitrogen temperature, compared to 95.8 percent at room temperature. Power MOSFET operation improved significantly where as the output rectifier operation deteriorated at low-temperature. The performance of the output filter inductor and capacitor did not change significantly at 77 K compared to room temperature performance. It is possible to achieve high-density and high efficiency power conversion at low-temperatures due to improved electronic, electrical and thermal properties of materials.

Epitaxial Ferroelectric Ba(0.5)Sr(0.5)TiO3 Thin Films for Room-Temperature High-Frequency Tunable Element Applications

NASA Technical Reports Server (NTRS)

Chen, C. L.; Feng, H. H.; Zhang, Z.; Brazdeikis, A.; Miranda, F. A.; VanKeuls, F. W.; Romanofsky, R. R.; Huang, Z. J.; Liou, Y.; Chu, W. K.;

Angle-resolved and core-level photoemission study of interfacing the topological insulator Bi1.5Sb0.5Te1.7Se1.3 with Ag, Nb, and Fe

NASA Astrophysics Data System (ADS)

de Jong, N.; Frantzeskakis, E.; Zwartsenberg, B.; Huang, Y. K.; Wu, D.; Hlawenka, P.; Sańchez-Barriga, J.; Varykhalov, A.; van Heumen, E.; Golden, M. S.

2015-08-01

Interfaces between a bulk-insulating topological insulator (TI) and metallic adatoms have been studied using high-resolution, angle-resolved, and core-level photoemission. Fe, Nb, and Ag were evaporated onto Bi1 .5Sb0 .5Te1 .7Se1 .3 (BSTS) surfaces both at room temperature and 38 K. The coverage and temperature dependence of the adsorption and interfacial formation process have been investigated, highlighting the effects of the overlayer growth on the occupied electronic structure of the TI. For all coverages at room temperature and for those equivalent to less than 0.2 monolayer at low temperature all three metals lead to a downward shift of the TI bands with respect to the Fermi level. At room temperature Ag appears to intercalate efficiently into the van der Waals gap of BSTS, accompanied by low-level substitution for the Te/Se atoms of the termination layer of the crystal. This Te/Se substitution with silver increases significantly for low temperature adsorption, and can even dominate the electrostatic environment of the Bi/Sb atoms in the BSTS near-surface region. On the other hand, Fe and Nb evaporants remain close to the termination layer of the crystal. On room temperature deposition, they initially substitute isoelectronically for Bi as a function of coverage, before substituting for Te/Se atoms. For low temperature deposition, Fe and Nb are too immobile for substitution processes and show a behavior consistent with clustering on the surface. For both Ag and Fe/Nb, these differing adsorption pathways still lead to the qualitatively similar and remarkable behavior for low temperature deposition that the chemical potential first moves downward (p -type dopant behavior) and then upward (n -type behavior) on increasing coverage.

Effect of Carbon Nanotube on High-Temperature Formability of AZ31 Magnesium Alloy

NASA Astrophysics Data System (ADS)

Hassan, S. Fida; Paramsothy, M.; Gasem, Z. M.; Patel, F.; Gupta, M.

2014-08-01

Room-temperature tensile properties of AZ31 alloy have significantly been improved when reinforced with carbon nanotube via ingot metallurgy process. However, high-temperature (up to 250 °C) elongation-to-failure tensile test of the developed nanocomposite revealed a considerable softening in the AZ31 alloy matrix accompanied by an incredible ductility increment (up to 132%). Microstructural characterization of the fractured samples revealed that the dynamic recrystallization process has induced a complete recrystallization in the AZ31 alloy at a lower temperature (150 °C) followed by substantial grain growth at a higher temperature used in this study. Fractography on the fractured surfaces revealed that the room-temperature mixed brittle-ductile modes of fracture behavior of AZ31 alloy have transformed into a complete ductile mode of fracture at high temperature.

Electric Field Dependence of Quantum Efficiencies of Ag/n-Si Composites in the Infrared at Room Temperature

DTIC Science & Technology

2009-09-10

Howard University 2300 6th Street NW, Room 1016 Washington, D.C. 20059 Air Force Office of Scientific Research 875 North Randolph Street Room 3112...Department of Electrical Engineering, Howard University , Washington, DC 20059 Room temperature quantum efficiencies of Ag/n-Si composite...at the Howard University CREST Center for Nanomaterials Characterization Science and Processing Technology were used in this investigation. The

46 CFR 111.01-15 - Temperature ratings.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS... assumed for all rotating electrical machinery in boiler rooms, engine rooms, auxiliary machinery rooms...-rotating electrical equipment in boiler rooms, in engine rooms, in auxiliary machinery rooms, and on...

46 CFR 111.01-15 - Temperature ratings.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS... assumed for all rotating electrical machinery in boiler rooms, engine rooms, auxiliary machinery rooms...-rotating electrical equipment in boiler rooms, in engine rooms, in auxiliary machinery rooms, and on...

Proinsulin is stable at room temperature for 24 hours in EDTA: A clinical laboratory analysis (adAPT 3)

PubMed Central

Davidson, Jane; McDonald, Timothy; Sutherland, Calum; Mostazir, Mohammod; VanAalten, Lidy

2017-01-01

Aims Reference laboratories advise immediate separation and freezing of samples for the assay of proinsulin, which limit its practicability for smaller centres. Following the demonstration that insulin and C-peptide are stable in EDTA at room temperature for at least 24hours, we undertook simple stability studies to establish whether the same might apply to proinsulin. Methods Venous blood samples were drawn from six adult women, some fasting, some not, aliquoted and assayed immediately and after storage at either 4°C or ambient temperature for periods from 2h to 24h. Results There was no significant variation or difference with storage time or storage condition in either individual or group analysis. Conclusion Proinsulin appears to be stable at room temperature in EDTA for at least 24h. Immediate separation and storage on ice of samples for proinsulin assay is not necessary, which will simplify sample transport, particularly for multicentre trials. PMID:28426711

Correlation between structural, electrical and magnetic properties of GdMnO3 bulk ceramics

NASA Astrophysics Data System (ADS)

Samantaray, S.; Mishra, D. K.; Pradhan, S. K.; Mishra, P.; Sekhar, B. R.; Behera, Debdhyan; Rout, P. P.; Das, S. K.; Sahu, D. R.; Roul, B. K.

2013-08-01

This paper reports the effect of sintering temperature on ferroelectric properties of GdMnO3 (GMO) bulk ceramics at room temperature prepared by the conventional solid state reaction route following slow step sintering schedule. Ferroelectric hysteresis loop as well as sharp dielectric anomaly in pure (99.999%) GMO sintered ceramics has been clearly observed. Samples sintered at 1350 °C become orthorhombic with Pbnm space group and showed frequency independent sharp dielectric anomalies at 373 K and a square type of novel ferroelectric hysteresis loop was observed at room temperature. Interestingly, dielectric anomalies and ferroelectric behavior were observed to be dependent upon sintering temperature of GdMnO3. Room temperature dielectric constant (ɛr) value at different frequencies is observed to be abnormally high. The magnetic field and temperature dependent magnetization show antiferromagnetic behavior at 40 K for both 1350 °C and 1700 °C sintered GMO. Present findings showed the possibility of application of GdMnO3 at room temperature as multifunctional materials.

Design of a Tunable, Room Temperature, Continuous-Wave Terahertz Source and Detector using Silicon Waveguides

DTIC Science & Technology

2008-01-30

that will use conventional diode- or hotomultiplier-tube-based optical detectors , which are xtremely sensitive . . HEATING AND FREE-CARRIER IMITATIONS...CONTRACT NUMBER IN-HOUSE Design of a tunable, room temperature, continuous-wave terahertz source and detector using silicon waveguides 5b. GRANT...B 261Design of a tunable, room temperature, continuous-wave terahertz source and detector using silicon waveguides T. Baehr-Jones,1,* M. Hochberg,1,3

Characterization of the magnetic properties of NdFeB thick films exposed to elevated temperatures

NASA Astrophysics Data System (ADS)

Fujiwara, Ryogen; Devillers, Thibaut; Givord, Dominique; Dempsey, Nora M.

2018-05-01

Hard magnetic films used in magnetic micro-systems may be exposed to elevated temperatures during film and system fabrication and also during use of the micro-system. In this work, we studied the influence of temperature on the magnetic properties of 10 μm thick out-of-plane textured NdFeB films fabricated by high rate triode sputtering. Out-of-plane hysteresis loops were measured in the range 300K - 650K to establish the temperature dependence of coercivity, magnetization at 7 T and remanent magnetization. Thermal demagnetization was measured and magnetization losses were recorded from 350K in films heated under zero or low (-0.1 T) external field and from 325 K for films heated under an external field of -0.5 T. The effect of thermal cycling under zero field on the remanent magnetization was also studied and it was found that cycling between room temperature and 323 K did not lead to any significant loss in remanence at room temperature, while a 4% drop is recorded when the sample is cycled between RT and 343K. Measurement of hysteresis loops at room temperature following exposure to elevated temperatures reveals that while remanent magnetisation is practically recovered in all cases, irreversible losses in coercivity occur (6.7 % following heating to 650K, and 1.3 % following heating to 343K). The relevance of these results is discussed in terms of system fabrication and use.

Stability of dronabinol capsules when stored frozen, refrigerated, or at room temperature.

PubMed

Wempe, Michael F; Oldland, Alan; Stolpman, Nancy; Kiser, Tyree H

2016-07-15

Results of a study to determine the 90-day stability of dronabinol capsules stored under various temperature conditions are reported. High-performance liquid chromatography (HPLC) with ultraviolet (UV) detection was used to assess the stability of dronabinol capsules (synthetic delta-9-tetrahydrocannabinol [Δ9-THC] mixed with high-grade sesame oil and other inactive ingredients and encapsulated as soft gelatin capsules) that were frozen, refrigerated, or kept at room temperature for three months. The dronabinol capsules remained in the original foil-sealed blister packs until preparation for HPLC-UV assessment. The primary endpoint was the percentage of the initial Δ9-THC concentration remaining at multiple designated time points. The secondary aim was to perform forced-degradation studies under acidic conditions to demonstrate that the HPLC-UV method used was stability indicating. The appearance of the dronabinol capsules remained unaltered during frozen, cold, or room-temperature storage. Regardless of storage condition, the percentage of the initial Δ9-THC content remaining was greater than 97% for all evaluated samples at all time points over the three-month study. These experimental data indicate that the product packaging and the sesame oil used to formulate dronabinol capsules efficiently protect Δ9-THC from oxidative degradation to cannabinol; this suggests that pharmacies can store dronabinol capsules in nonrefrigerated automated dispensing systems, with a capsule expiration date of 90 days after removal from the refrigerator. Dronabinol capsules may be stored at room temperature in their original packaging for up to three months without compromising capsule appearance and with minimal reduction in Δ9-THC concentration. Copyright © 2016 by the American Society of Health-System Pharmacists, Inc. All rights reserved.

Electron-Transfer Ion/Ion Reactions of Doubly Protonated Peptides: Effect of Elevated Bath Gas Temperature

PubMed Central

Pitteri, Sharon J.; Chrisman, Paul A.; McLuckey, Scott A.

2005-01-01

In this study, the electron-transfer dissociation (ETD) behavior of cations derived from 27 different peptides (22 of which are tryptic peptides) has been studied in a 3D quadrupole ion trap mass spectrometer. Ion/ion reactions between peptide cations and nitrobenzene anions have been examined at both room temperature and in an elevated temperature bath gas environment to form ETD product ions. From the peptides studied, the ETD sequence coverage tends to be inversely related to peptide size. At room temperature, very high sequence coverage (~100%) was observed for small peptides (≤7 amino acids). For medium-sized peptides composed of 8–11 amino acids, the average sequence coverage was 46%. Larger peptides with 14 or more amino acids yielded an average sequence coverage of 23%. Elevated-temperature ETD provided increased sequence coverage over room-temperature experiments for the peptides of greater than 7 residues, giving an average of 67% for medium-sized peptides and 63% for larger peptides. Percent ETD, a measure of the extent of electron transfer, has also been calculated for the peptides and also shows an inverse relation with peptide size. Bath gas temperature does not have a consistent effect on percent ETD, however. For the tryptic peptides, fragmentation is localized at the ends of the peptides suggesting that the distribution of charge within the peptide may play an important role in determining fragmentation sites. A triply protonated peptide has also been studied and shows behavior similar to the doubly charged peptides. These preliminary results suggest that for a given charge state there is a maximum size for which high sequence coverage is obtained and that increasing the bath gas temperature can increase this maximum. PMID:16131079

Evaluation of Energy Efficiency Performance of Heated Windows

NASA Astrophysics Data System (ADS)

Jammulamadaka, Hari Swarup

The study about the evaluation of the performance of the heated windows was funded by the WVU Research Office as a technical assistance award at the 2014 TransTech Energy Business Development Conference to the Green Heated Glass company/project owned by Frank Dlubak. The award supports a WVU researcher to conduct a project important for commercialization. This project was awarded to the WVU Industrial Assessment Center in 2015. The current study attempted to evaluate the performance of the heated windows by developing an experimental setup to test the window at various temperatures by varying the current input to the window. The heated double pane window was installed in an insulated box. A temperature gradient was developed across the window by cooling one side of the window using gel based ice packs. The other face of the window was heated by passing current at different wattages through the window. The temperature of the inside and outside panes, current and voltage input, room and box temperature were recorded, and used to calculate the apparent R-value of the window when not being heated vs when being heated. It has been concluded from the study that the heated double pane window is more effective in reducing heat losses by as much as 50% than a non-heated double pane window, if the window temperature is maintained close to the room temperature. If the temperature of the window is much higher than the room temperature, the losses through the window appear to increase beyond that of a non-heated counterpart. The issues encountered during the current round of experiments are noted, and recommendations provided for future studies.

Differences between the most used equations in BAT-human studies to estimate parameters of skin temperature in young lean men.

PubMed

Martinez-Tellez, Borja; Sanchez-Delgado, Guillermo; Acosta, Francisco M; Alcantara, Juan M A; Boon, Mariëtte R; Rensen, Patrick C N; Ruiz, Jonatan R

2017-09-05

Cold exposure is necessary to activate human brown adipose tissue (BAT), resulting in heat production. Skin temperature is an indirect measure to monitor the body's reaction to cold. The aim of this research was to study whether the most used equations to estimate parameters of skin temperature in BAT-human studies measure the same values of temperature in young lean men (n = 11: 23.4 ± 0.5 years, fat mass: 19.9 ± 1.2%). Skin temperature was measured with 26 ibuttons at 1-minute intervals in warm and cold room conditions. We used 12 equations to estimate parameters of mean, proximal, and distal skin temperature as well as skin temperature gradients. Data were analysed with Temperatus software. Significant differences were found across equations to measure the same parameters of skin temperature in warm and cold room conditions, hampering comparison across studies. Based on these findings, we suggest to use a set of 14 ibuttons at anatomical positions reported by ISO STANDARD 9886:2004 plus five ibuttons placed on the right supraclavicular fossa, right middle clavicular bone, right middle upper forearm, right top of forefinger, and right upper chest.

Magnetocaloric effect study of Pr0.67Ca0.33MnO3-La0.67Sr0.33MnO3 nanocomposite

NASA Astrophysics Data System (ADS)

Das, Kalipada; Roy Chowdhury, R.; Midda, S.; Sen, Pintu; Das, I.

2018-03-01

The present study involves investigaton of magnetocaloric effect of Pr0.67Ca0.33MnO3-La0.67Sr0.33MnO3 nanocomposite materials above room temperature. From application point of view in magnetic refrigeration our study highlights the enhancement of operating temperature region compared to the well known La0.67Sr0.33MnO3 refrigerant material above room temperature. Comparison has also been made with the magnetocaloric properties of La0.67Sr0.33MnO3 nanomaterials. The modification of the magnetocaloric entropy changes (broadening of the temperature dependent magnetic entropy change) is addressed due to the effect of the gradual melting of antiferromagnetic charge ordered state of the Pr0.67Ca0.33MnO3 nanoparticles in such nanocomposite materials.

Basic Studies Relative to the Syntheses of Unsymmetrical Dimethylhydrazine and Monomethylhydrazine by Chloramination

DTIC Science & Technology

1979-12-07

8217 changed to faint yellow. After the chloramination, the reaction mixture was allowed to stand at room temperature to allow volatile gases to ’escape. The...energy rocketI and space shuttle fuels. These compounds have large heats of combustion , relatively :,igh densities and high specific impulses. Until...a solution of KOH in n-butanol was carried out in the presence of NH3 at room temperature . The major products were 1,1-dimethylhydrazine, the

DOE Office of Scientific and Technical Information (OSTI.GOV)

Demidov, V. E.; Dzyapko, O.; Demokritov, S. O.

The room-temperature dynamics of a magnon gas driven by short microwave pumping pulses is studied. An overpopulation of the lowest energy level of the system following the pumping is observed. Using the sensitivity of the Brillouin light scattering technique to the coherence degree of the scattering magnons we demonstrate the spontaneous emergence of coherence of the magnons at the lowest level, if their density exceeds a critical value. This finding is clear proof of the quantum nature of the observed phenomenon and direct evidence of Bose-Einstein condensation of magnons at room temperature.

Analysis of Thickness and Quality factor of a Double Paddle Oscillator at Room Temperature.

PubMed

Shakeel, Hamza; Metcalf, Thomas H; Pomeroy, J M

2016-01-01

In this paper, we evaluate the quality (Q) factor and the resonance frequency of a double paddle oscillator (DPO) with different thickness using analytical, computational and experimental methods. The study is carried out for the 2 nd anti-symmetric resonance mode that provides extremely high experimental Q factors on the order of 10 5 . The results show that both the Q factor and the resonance frequency of a DPO increase with the thickness at room temperature.

Strength evaluation test of pressureless-sintered silicon nitride at room temperature

NASA Technical Reports Server (NTRS)

Matsusue, K.; Takahara, K.; Hashimoto, R.

1984-01-01

In order to study strength characteristics at room temperature and the strength evaluating method of ceramic materials, the following tests were conducted on pressureless sintered silicon nitride specimens: bending tests, the three tensile tests of rectangular plates, holed plates, and notched plates, and spin tests of centrally holed disks. The relationship between the mean strength of specimens and the effective volume of specimens are examined using Weibull's theory. The effect of surface grinding on the strength of specimens is discussed.

Polarization characteristic of a room-temperature Co:MgF2 laser.

PubMed

Zhang, Zengming M; Cui, Yiben B; Li, Fuli L; Zhang, Guobin B; Pu, Qirong R; Xu, Gaojie J

2002-02-20

A study of the polarization characteristic of a Co:MgF2 laser with a 1320-nm YAG pumping laser at room temperature is reported. The thresholds, output energies, and efficiencies of the laser are given at the various polarization states. The more intensive emission is in the pi-polarization pump laser and sigma-polarization laser operation. Performances of the Co:MgF2 lasers are similar for the polarized and unpolarized laser pumping along the optical axis of the crystal.

High-temperature mechanical properties of a solid oxide fuel cell glass sealant in sintered forms

NASA Astrophysics Data System (ADS)

Chang, Hsiu-Tao; Lin, Chih-Kuang; Liu, Chien-Kuo; Wu, Szu-Han

High-temperature mechanical properties of a silicate-based glass sealant (GC-9) for planar solid oxide fuel cell have been studied in sintered forms. Ring-on-ring biaxial flexural tests are carried out at room temperature to 800 °C for the sintered GC-9 glass. The results are also compared with those in cast bulk forms. From the force-displacement curves, the glass transition temperature (T g) of the non-aged, sintered GC-9 glass is estimated to be between 700 °C and 750 °C, while that of the aged one is between 750 °C and 800 °C. Due to a crack healing effect of the residual glass at high temperature, the flexural strength of the sintered GC-9 glass at temperature of 650 °C to T g point is greater than that at room temperature. At temperature above T g, the flexural strength and stiffness are considerably reduced to a level lower than the room-temperature one. The sintered GC-9 glass with pores and crystalline phases has a flexural strength lower than the cast bulk one at temperature of 650 °C and below. Due to a greater extent of crystallization, the flexural strength and stiffness of the sintered GC-9 glass are greater than those of the cast bulk one at 700-800 °C.

A randomised single blinded study of the administration of pre-warmed fluid vs active fluid warming on the incidence of peri-operative hypothermia in short surgical procedures.

PubMed

Andrzejowski, J C; Turnbull, D; Nandakumar, A; Gowthaman, S; Eapen, G

2010-09-01

We compared the effect of delivering fluid warmed using two methods in 76 adult patients having short duration surgery. All patients received a litre of crystalloid delivered either at room temperature, warmed using an in-line warming device or pre-warmed in a warming cabinet for at least 8 h. The tympanic temperature of those receiving fluid at room temperature was 0.4 °C lower on arrival in recovery when compared with those receiving fluid from a warming cabinet (p = 0.008). Core temperature was below the hypothermic threshold of 36.0 °C in seven (14%) patients receiving either type of warm fluid, compared to eight (32%) patients receiving fluid at room temperature (p = 0.03). The administration of 1 l warmed fluid to patients having short duration general anaesthesia results in higher postoperative temperatures. Pre-warmed fluid, administered within 30 min of its removal from a warming cabinet, is as efficient at preventing peri-operative hypothermia as that delivered through an in-line warming system. © 2010 The Authors. Journal compilation © 2010 The Association of Anaesthetists of Great Britain and Ireland.

Characterization and prediction of rate-dependent flexibility in lumbar spine biomechanics at room and body temperature.

PubMed

Stolworthy, Dean K; Zirbel, Shannon A; Howell, Larry L; Samuels, Marina; Bowden, Anton E

2014-05-01

The soft tissues of the spine exhibit sensitivity to strain-rate and temperature, yet current knowledge of spine biomechanics is derived from cadaveric testing conducted at room temperature at very slow, quasi-static rates. The primary objective of this study was to characterize the change in segmental flexibility of cadaveric lumbar spine segments with respect to multiple loading rates within the range of physiologic motion by using specimens at body or room temperature. The secondary objective was to develop a predictive model of spine flexibility across the voluntary range of loading rates. This in vitro study examines rate- and temperature-dependent viscoelasticity of the human lumbar cadaveric spine. Repeated flexibility tests were performed on 21 lumbar function spinal units (FSUs) in flexion-extension with the use of 11 distinct voluntary loading rates at body or room temperature. Furthermore, six lumbar FSUs were loaded in axial rotation, flexion-extension, and lateral bending at both body and room temperature via a stepwise, quasi-static loading protocol. All FSUs were also loaded using a control loading test with a continuous-speed loading-rate of 1-deg/sec. The viscoelastic torque-rotation response for each spinal segment was recorded. A predictive model was developed to accurately estimate spine segment flexibility at any voluntary loading rate based on measured flexibility at a single loading rate. Stepwise loading exhibited the greatest segmental range of motion (ROM) in all loading directions. As loading rate increased, segmental ROM decreased, whereas segmental stiffness and hysteresis both increased; however, the neutral zone remained constant. Continuous-speed tests showed that segmental stiffness and hysteresis are dependent variables to ROM at voluntary loading rates in flexion-extension. To predict the torque-rotation response at different loading rates, the model requires knowledge of the segmental flexibility at a single rate and specified temperature, and a scaling parameter. A Bland-Altman analysis showed high coefficients of determination for the predictive model. The present work demonstrates significant changes in spine segment flexibility as a result of loading rate and testing temperature. Loading rate effects can be accounted for using the predictive model, which accurately estimated ROM, neutral zone, stiffness, and hysteresis within the range of voluntary motion. Copyright © 2014 Elsevier Inc. All rights reserved.

Amorphization of nanocrystalline 3C-SiC irradiated with Si+ ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Weilin; Wang, Haiyan; Kim, Ickchan

2010-11-23

Irradiation induced amorphization in nanocrystalline and single crystal 3C-SiC has been studied using 1 MeV Si+ ions under the identical irradiation conditions at room temperature and 400 K. The disordering behavior has been characterized using in-situ ion channeling and ex-situ x-ray diffraction methods. The results show that, compared to single crystal 3C-SiC, full amorphization of small 3C-SiC grains (~3.8 nm in size) occurs at a slightly lower dose at room temperature. For grains with sizes of 3.0 - 3.8 nm, the amorphization dose is lower at room temperature than 400 K. A significantly lower dose for amorphization of smaller grainsmore » (2.0 nm in size) is observed at 400 K. The behavior has been interpreted based on the competition between the interface and interior amorphization.« less

The structural properties of InGaN alloys and the interdependence on the thermoelectric behavior

NASA Astrophysics Data System (ADS)

Kucukgok, Bahadir; Wu, Xuewang; Wang, Xiaojia; Liu, Zhiqiang; Ferguson, Ian T.; Lu, Na

2016-02-01

The III-Nitrides are promising candidate for high efficiency thermoelectric (TE) materials and devices due to their unique features which includes high thermal stability. A systematic study of the room temperature TE properties of metalorganic chemical vapor deposition grown InxGa1-xN were investigated for x = 0.07 to 0.24. This paper investigated the role of indium composition on the TE properties of InGaN alloys in particular the structural properties for homogenous material that did not show significant phase separation. The highest Seebeck and power factor values of 507 μV K-1 and 21.84 × 10-4 Wm-1K-1 were observed, respectively for In0.07Ga0.93N at room temperature. The highest value of figure-of-merit (ZT) was calculated to be 0.072 for In0.20Ga0.80N alloy at room temperature.

Entanglement and Bell's inequality violation above room temperature in metal carboxylates

NASA Astrophysics Data System (ADS)

Souza, A. M.; Soares-Pinto, D. O.; Sarthour, R. S.; Oliveira, I. S.; Reis, M. S.; Brandão, P.; Dos Santos, A. M.

2009-02-01

In the present work we show that a particular family of materials, the metal carboxylates, may have entangled states up to very high temperatures. From magnetic-susceptibility measurements, we have estimated the critical temperature below which entanglement exists in the copper carboxylate {Cu2(O2CH)4}{Cu(O2CH)2(2-methylpyridine)2} , and we have found this to be above room temperature (Te˜630K) . Furthermore, the results show that the system remains maximally entangled until close to ˜100K and the Bell’s inequality is violated up to nearly room temperature (˜290K) .

Entanglement and Bell's inequality violation above room temperature in metal carboxylates.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Souza, A M; Soares-Pinto, D O; Sarthour, R S

In the present work we show that a particular family of materials, the metal carboxylates, may have entangled states up to very high temperatures. From magnetic-susceptibility measurements, we have estimated the critical temperature below which entanglement exists in the copper carboxylate {Cu-2(O2CH)(4)}{Cu(O2CH)(2)(2-methylpyridine)(2)}, and we have found this to be above room temperature (T-e similar to 630 K). Furthermore, the results show that the system remains maximally entangled until close to similar to 100 K and the Bell's inequality is violated up to nearly room temperature (similar to 290 K).

Tailoring the magnetostructural transition and magnetocaloric properties around room temperature: In-doped Ni-Mn-Ga alloys

NASA Astrophysics Data System (ADS)

Zhang, Linfang; Wang, Jingmin; Hua, Hui; Jiang, Chengbao; Xu, Huibin

2014-09-01

Some off-stoichiometric Ni-Mn-Ga alloys undergo a coupled magnetostructural transition from ferromagnetic martensite to paramagnetic austenite, giving rise to the large magnetocaloric effect. However, the magnetostructural transitions of Ni-Mn-Ga alloys generally take place at temperatures higher than room temperature. Here, we report that by the partial substitution of In for Ga, the paramagnetic austenite phase is well stabilized, and the magnetostructural transition can be tailored around room temperature. Sizable magnetic entropy change and adiabatic temperature change were induced by magnetic field change in the vicinity of the magnetostructural transition of the In-doped Ni-Mn-Ga alloys.

The effect of high indoor temperatures on self-perceived health of elderly persons.

PubMed

van Loenhout, J A F; le Grand, A; Duijm, F; Greven, F; Vink, N M; Hoek, G; Zuurbier, M

2016-04-01

Exposure to high ambient temperatures leads to an increase in mortality and morbidity, especially in the elderly. This relationship is usually assessed with outdoor temperature, even though the elderly spend most of their time indoors. Our study investigated the relationship between indoor temperature and heat-related health problems of elderly individuals. The study was conducted in the Netherlands between April and August 2012. Temperature and relative humidity were measured continuously in the living rooms and bedrooms of 113 elderly individuals. Respondents were asked to fill out an hourly diary during three weeks with high temperature and one cold reference week, and a questionnaire at the end of these weeks, on health problems that they experienced due to heat. During the warmest week of the study period (14-20 August), average living room and bedroom temperatures were approximately 5°C higher than during the reference week. More than half of the respondents perceived their indoor climate as too warm during this week. The most reported symptoms were thirst (42.7%), sleep disturbance (40.6%) and excessive sweating (39.6%). There was a significant relationship between both indoor and outdoor temperatures with the number of hours that heat-related health problems were reported per day. For an increase of 1°C of indoor temperature, annoyance due to heat and sleep disturbance increased with 33% and 24% respectively. Outdoor temperature was associated with smaller increases: 13% and 11% for annoyance due to heat and sleep disturbance, respectively. The relationship between outdoor temperature and heat-related health problems disappeared when indoor and outdoor temperatures were included in one model. The relationship with heat-related health problems in the elderly is stronger with indoor (living room and bedroom) temperature than with outdoor temperature. This should be taken into account when looking for measures to reduce heat exposure in this vulnerable group. Copyright © 2015 Elsevier Inc. All rights reserved.

Evaluation of Ultra High Pressure (UHP) Firefighting in a Room-and-Contents Fire

DTIC Science & Technology

2017-03-15

Burn Room and Hangar Temperature Prior to Ignition ............................................... 18 Figure 12. Effect of Temperature on Normalized...Figure 20. Maximum Average Temperature and Heat Flux ......................................................... 22 Figure 21. Effect of Maximum Average...Aspirated Ceiling Temperature .................................... 23 Figure 22. Effect of Maximum Average Floor Heat Flux on Extinguishment Quantity

Enhanced O-2 Selectivity versus N-2 by Partial Metal Substitution in Cu-BTC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sava Gallis, Dorina F.; Parkes, Marie V.; Greathouse, Jeffery A.

2015-03-24

Here, we describe the homogeneous substitution of Mn, Fe, and Co at various levels into a prototypical metal organic framework (MOP), namely Cu-BTC (HKUST-1), and the effect of that substitution on preferential gas sorption. Using a combination of density functional theory (DFT) calculations, postsynthetic metal substitutions, materials characterization, and gas sorption testing, we demonstrate that the identity of the metal ion has a quantifiable effect on their oxygen and nitrogen sorption properties at cryogenic temperatures. An excellent correlation is found between O-2/N-2 selectivities determined experimentally at 77 K and the difference in O-2 and N-2 binding energies calculated from DFTmore » modeling data: Mn > Fe Co >> Cu. Room temperature gas sorption studies were also performed and correlated with metal substitution. The Fe-exchanged sample shows a significantly higher nitrogen isosteric heat of adsorption at temperatures close to ambient conditions (273-298 K) as compared to all other metals studied, indicative of favorable interactions between N-2 and coordinatively unsaturated Fe metal centers. Interestingly, differences in gas adsorption results at cryogenic and room temperatures are evident; they are explained by comparing experimental results with DFT binding energies (0 K) and room temperature Grand Canonical Monte Carlo simulations.« less

Enhanced O 2 selectivity versus N 2 by partial metal substitution in Cu-BTC

DOE PAGES

Sava Gallis, Dorina F.; Parkes, Marie V.; Greathouse, Jeffery A.; ...

2015-03-05

Here we describe the homogeneous substitution of Mn, Fe and Co at various levels into a prototypical metal-organic framework (MOF), namely Cu-BTC (HKUST-1), and the effect of that substitution on preferential gas sorption. Using a combination of density functional theory (DFT) calculations, postsynthetic metal substitutions, materials characterization, and gas sorption testing, we demonstrate that the identity of the metal ion has a quantifiable effect on their oxygen and nitrogen sorption properties at cryogenic temperatures. An excellent correlation is found between O 2/N 2 selectivities determined experimentally at 77 K and the difference in O 2 and N 2 binding energiesmore » calculated from DFT modeling data: Mn > Fe > Co > Cu. Room temperature gas sorption studies were also performed and correlated with metal substitution. The Fe-exchanged sample shows a significantly higher nitrogen isosteric heat of adsorption at temperatures close to ambient conditions (273 K - 298 K) as compared to all other metals studied, indicative of favorable interactions between N 2 and coordinatively unsaturated Fe metal centers. Furthermore, differences in gas adsorption results at cryogenic and room temperatures are evident; they are explained by comparing experimental results with DFT binding energies (0 K) and room temperature Grand Canonical Monte Carlo simulations.« less

Stability of procalcitonin at room temperature.

PubMed

Milcent, Karen; Poulalhon, Claire; Fellous, Christelle Vauloup; Petit, François; Bouyer, Jean; Gajdos, Vincent

2014-01-01

The aim was to assess procalcitonin (PCT) stability after two days of storage at room temperature. Samples were collected from febrile children aged 7 to 92 days and were rapidly frozen after sampling. PCT levels were measured twice after thawing: immediately (named y) and 48 hours later after storage at room temperature (named x). PCT values were described with medians and interquartile ranges or by categorizing them into classes with thresholds 0.25, 0.5, and 2 ng/mL. The relationship between x and y PCT levels was analyzed using fractional polynomials in order to predict the PCT value immediately after thawing (named y') from x. A significant decrease in PCT values was observed after 48 hours of storage at room temperature, either in median, 30% lowering (p < 0.001), or as categorical variable (p < 0.001). The relationship between x and y can be accurately modeled with a simple linear model: y = 1.37 x (R2 = 0.99). The median of the predicted PCT values y' was quantitatively very close to the median of y and the distributions of y and y' across categories were very similar and not statistically different. PCT levels noticeably decrease after 48 hours of storage at room temperature. It is possible to pre- dict accurately effective PCT values from the values after 48 hours of storage at room temperature with a simple statistical model.

Optimized postweld heat treatment procedures for 17-4 PH stainless steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bhaduri, A.K.; Sujith, S.; Srinivasan, G.

1995-05-01

The postweld heat treatment (PWHT) procedures for 17-4 PH stainless steel weldments of matching chemistry was optimized vis-a-vis its microstructure prior to welding based on microstructural studies and room-temperature mechanical properties. The 17-4 PH stainless steel was welded in two different prior microstructural conditions (condition A and condition H 1150) and then postweld heat treated to condition H900 or condition H1150, using different heat treatment procedures. Microstructural investigations and room-temperature tensile properties were determined to study the combined effects of prior microstructural and PWHT procedures.

A Chitosan Coating Containing Essential Oil from Origanum vulgare L. to Control Postharvest Mold Infections and Keep the Quality of Cherry Tomato Fruit

PubMed Central

Barreto, Tainá A.; Andrade, Sonalle C. A.; Maciel, Janeeyre F.; Arcanjo, Narciza M. O.; Madruga, Marta S.; Meireles, Bruno; Cordeiro, Ângela M. T.; Souza, Evandro L.; Magnani, Marciane

2016-01-01

The efficacy of an edible chitosan coating (CHI; 4 mg/mL) and Origanum vulgare L. essential oil (OVEO; 1.25 μL/mL) for maintaining the quality of cherry tomato fruit during storage at room (25°C; 12 days) and cold (12°C; 24 days) temperatures was assessed. CHI and OVEO in combination showed in vitro fungicidal effects against R. stolonifer and Aspergillus niger. CHI-OVEO coating reduced the incidence of black mold and soft rot caused by these fungi in artificially contaminated cherry tomato fruit during storage at both temperatures. CHI-OVEO coating delayed the appearance of the first visible signs of black mold and soft rot in artificially contaminated cherry tomato fruit stored at room temperature by 6 days and by more than 9 days in those stored at cold temperature. At the end of storage at room and cold temperature fruit coated with CHI-OVEO showed higher firmness (>2 N/mm) and lower weight loss (>2%) compared to uncoated tomato fruit. CHI-OVEO coating delayed the decrease of lycopene, ascorbic citric acid, glucose and fructose during the storage time assessed at room or cold temperatures. The increase of catechin, myricetin, caffeic and syringic acids was higher (1–9 mg/g) in cherry tomato fruit coated with CHI-OVEO compared to uncoated fruit during the storage at both temperatures studied. CHI-OVEO coating is a feasible treatment for maintaining the storage quality of cherry tomato fruit. PMID:27877156

Annealing effects on room temperature thermoelectric performance of p-type thermally evaporated Bi-Sb-Te thin films

NASA Astrophysics Data System (ADS)

Singh, Sukhdeep; Singh, Janpreet; Tripathi, S. K.

2018-05-01

Bismuth antimony telluride (Bi-Sb-Te) compounds have been investigated for the past many decades for thermoelectric (TE) power generation and cooling purpose. We synthesized this compound with a stoichiometry Bi1.2Sb0.8Te3 through melt cool technique and thin films of as synthesized material were deposited by thermal evaporation. The prime focus of the present work is to study the influence of annealing temperature on the room temperature (RT) power factor of thin films. Electrical conductivity and Seebeck coefficient were studied and power factors were calculated which showed a peak value at 323 K. The compounds performance is comparable to some very efficient Bi-Sb-Te reported stoichiometries at RT scale. The values observed show that material has an enormous potential for energy production at ambient temperature scales.

Graphene-based room-temperature implementation of a modified Deutsch-Jozsa quantum algorithm.

PubMed

Dragoman, Daniela; Dragoman, Mircea

2015-12-04

We present an implementation of a one-qubit and two-qubit modified Deutsch-Jozsa quantum algorithm based on graphene ballistic devices working at room temperature. The modified Deutsch-Jozsa algorithm decides whether a function, equivalent to the effect of an energy potential distribution on the wave function of ballistic charge carriers, is constant or not, without measuring the output wave function. The function need not be Boolean. Simulations confirm that the algorithm works properly, opening the way toward quantum computing at room temperature based on the same clean-room technologies as those used for fabrication of very-large-scale integrated circuits.

Numerical modeling of cold room's hinged door opening and closing processes

NASA Astrophysics Data System (ADS)

Carneiro, R.; Gaspar, P. D.; Silva, P. D.; Domingues, L. C.

2016-06-01

The need of rationalize energy consumption in agrifood industry has fasten the development of methodologies to improve the thermal and energy performances of cold rooms. This paper presents a three-dimensional (3D) transient Computational Fluid Dynamics (CFD) modelling of a cold room to evaluate the air infiltration rate through hinged doors. A species transport model is used for modelling the tracer gas concentration decay technique. Numerical predictions indicate that air temperature difference between spaces affects the air infiltration. For this case study, the infiltration rate increases 0.016 m3 s-1 per K of air temperature difference. The knowledge about the evolution of air infiltration during door opening/closing times allows to draw some conclusions about its influence on the air conditions inside the cold room, as well as to suggest best practices and simple technical improvements that can minimize air infiltration, and consequently improve thermal performance and energy consumption rationalization.

Ordering of Zn-centered porphyrin and phthalocyanine on TiO2(011): STM studies

PubMed Central

Godlewski, Szymon; Such, Bartosz; Pawlak, Rémy; Hinaut, Antoine; Jöhr, Res; Glatzel, Thilo; Meyer, Ernst; Szymonski, Marek

2017-01-01

Zn(II)phthalocyanine molecules (ZnPc) were thermally deposited on a rutile TiO2(011) surface and on Zn(II)meso-tetraphenylporphyrin (ZnTPP) wetting layers at room temperature and after elevated temperature thermal processing. The molecular homo- and heterostructures were characterized by high-resolution scanning tunneling microscopy (STM) at room temperature and their geometrical arrangement and degree of ordering are compared with the previously studied copper phthalocyanine (CuPc) and ZnTPP heterostructures. It was found that the central metal atom may play some role in ordering and growth of phthalocyanine/ZnTPP heterostructures, causing differences in stability of upright standing ZnPc versus CuPc molecular chains at given thermal annealing conditions. PMID:28144569

The Bulk Nanocrystalline zn Produced by Mechanical Attrition

NASA Astrophysics Data System (ADS)

Zhu, X. K.; Zhao, K. Y.; Li, C. J.; Tao, J. M.; Chan, T. L.; Koch, C. C.

The purpose of experiment was to produce bulk nanocrystalline Zn by mechanical attrition. The bulk nanocrystalline Zn produced by mechanical attrition was studied. The microstructural evolution during cryomilling and subsequent room temperature milling was characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). In this paper, Nanocrystalline Zn was produced by insitu consolidation of Zn elemental powder using mechanical attrition at liquid nitrogen and room temperature. For the samples studied, the longest elongation of 65% and highest stress of 200 MPa is obtained in nanocrystalline Zn during tensile testing at the condition of strain rate (10-3 sec-1) and 20°C which is equal to 0.43 Tm (Tm is the melting temperature of pure Zn).

Curious Case of Positive Current Collectors: Corrosion and Passivation at High Temperature.

PubMed

Sayed, Farheen N; Rodrigues, Marco-Tulio F; Kalaga, Kaushik; Gullapalli, Hemtej; Ajayan, P M

2017-12-20

In the evaluation of compatibility of different components of cell for high-energy and extreme-conditions applications, the highly focused are positive and negative electrodes and their interaction with electrolyte. However, for high-temperature application, the other components are also of significant influence and contribute toward the total health of battery. In present study, we have investigated the behavior of aluminum, the most common current collector for positive electrode materials for its electrochemical and temperature stability. For electrochemical stability, different electrolytes, organic and room temperature ionic liquids with varying Li salts (LiTFSI, LiFSI), are investigated. The combination of electrochemical and spectroscopic investigations reflects the varying mechanism of passivation at room and high temperature, as different compositions of decomposed complexes are found at the surface of metals.

Room-temperature nine-µm-wavelength photodetectors and GHz-frequency heterodyne receivers.

PubMed

Palaferri, Daniele; Todorov, Yanko; Bigioli, Azzurra; Mottaghizadeh, Alireza; Gacemi, Djamal; Calabrese, Allegra; Vasanelli, Angela; Li, Lianhe; Davies, A Giles; Linfield, Edmund H; Kapsalidis, Filippos; Beck, Mattias; Faist, Jérôme; Sirtori, Carlo

2018-04-05

Room-temperature operation is essential for any optoelectronics technology that aims to provide low-cost, compact systems for widespread applications. A recent technological advance in this direction is bolometric detection for thermal imaging, which has achieved relatively high sensitivity and video rates (about 60 hertz) at room temperature. However, owing to thermally induced dark current, room-temperature operation is still a great challenge for semiconductor photodetectors targeting the wavelength band between 8 and 12 micrometres, and all relevant applications, such as imaging, environmental remote sensing and laser-based free-space communication, have been realized at low temperatures. For these devices, high sensitivity and high speed have never been compatible with high-temperature operation. Here we show that a long-wavelength (nine micrometres) infrared quantum-well photodetector fabricated from a metamaterial made of sub-wavelength metallic resonators exhibits strongly enhanced performance with respect to the state of the art up to room temperature. This occurs because the photonic collection area of each resonator is much larger than its electrical area, thus substantially reducing the dark current of the device. Furthermore, we show that our photonic architecture overcomes intrinsic limitations of the material, such as the drop of the electronic drift velocity with temperature, which constrains conventional geometries at cryogenic operation. Finally, the reduced physical area of the device and its increased responsivity allow us to take advantage of the intrinsic high-frequency response of the quantum detector at room temperature. By mixing the frequencies of two quantum-cascade lasers on the detector, which acts as a heterodyne receiver, we have measured a high-frequency signal, above four gigahertz (GHz). Therefore, these wide-band uncooled detectors could benefit technologies such as high-speed (gigabits per second) multichannel coherent data transfer and high-precision molecular spectroscopy.

Room-temperature nine-µm-wavelength photodetectors and GHz-frequency heterodyne receivers

NASA Astrophysics Data System (ADS)

Palaferri, Daniele; Todorov, Yanko; Bigioli, Azzurra; Mottaghizadeh, Alireza; Gacemi, Djamal; Calabrese, Allegra; Vasanelli, Angela; Li, Lianhe; Davies, A. Giles; Linfield, Edmund H.; Kapsalidis, Filippos; Beck, Mattias; Faist, Jérôme; Sirtori, Carlo

2018-04-01

Room-temperature operation is essential for any optoelectronics technology that aims to provide low-cost, compact systems for widespread applications. A recent technological advance in this direction is bolometric detection for thermal imaging, which has achieved relatively high sensitivity and video rates (about 60 hertz) at room temperature. However, owing to thermally induced dark current, room-temperature operation is still a great challenge for semiconductor photodetectors targeting the wavelength band between 8 and 12 micrometres, and all relevant applications, such as imaging, environmental remote sensing and laser-based free-space communication, have been realized at low temperatures. For these devices, high sensitivity and high speed have never been compatible with high-temperature operation. Here we show that a long-wavelength (nine micrometres) infrared quantum-well photodetector fabricated from a metamaterial made of sub-wavelength metallic resonators exhibits strongly enhanced performance with respect to the state of the art up to room temperature. This occurs because the photonic collection area of each resonator is much larger than its electrical area, thus substantially reducing the dark current of the device. Furthermore, we show that our photonic architecture overcomes intrinsic limitations of the material, such as the drop of the electronic drift velocity with temperature, which constrains conventional geometries at cryogenic operation. Finally, the reduced physical area of the device and its increased responsivity allow us to take advantage of the intrinsic high-frequency response of the quantum detector at room temperature. By mixing the frequencies of two quantum-cascade lasers on the detector, which acts as a heterodyne receiver, we have measured a high-frequency signal, above four gigahertz (GHz). Therefore, these wide-band uncooled detectors could benefit technologies such as high-speed (gigabits per second) multichannel coherent data transfer and high-precision molecular spectroscopy.

Mechanical properties of ZrB2- and HfB2-based ultra-high temperature ceramics fabricated by spark plasma sintering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zapata-Solvas, E.; Jayaseelan, D.; Lin, Hua-Tay

2013-01-01

Flexural strengths at room temperature, at 1400 C in air and at room temperature after 1 h oxidation at 1400 C were determined for ZrB2- and HfB2-based ultra-high temperature ceramics (UHTCs). Defects caused by electrical discharge machining (EDM) lowered measured strengths significantly and were used to calculate fracture toughness via a fracture mechanics approach. ZrB2 with 20 vol.% SiC had room temperature strength of 700 90 MPa, fracture toughness of 6.4 0.6 MPa, Vickers hardness at 9.8 N load of 21.1 0.6 GPa, 1400 C strength of 400 30 MPa and room temperature strength after 1 h oxidation at 1400more » C of 678 15 MPa with an oxide layer thickness of 45 5 m. HfB2 with 20 vol.% SiC showed room temperature strength of 620 50 MPa, fracture toughness of 5.0 0.4 MPa, Vickers hardness at 9.8 N load of 27.0 0.6 GPa, 1400 C strength of 590 150 MPa and room temperature strength after 1 h oxidation at 1400 C of 660 25 MPa with an oxide layer thickness of 12 1 m. 2 wt.% La2O3 addition to UHTCs slightly reduced mechanical performance while increasing tolerance to property degradation after oxidation and effectively aided internal stress relaxation during spark plasma sintering (SPS) cooling, as quantified by X-ray diffraction (XRD). Slow crack growth was suggested as the failure mechanism at high temperatures as a consequence of sharp cracks formation during oxidation.« less

Room-temperature multiferroic and magnetocapacitance effects in M-type hexaferrite BaFe{sub 10.2}Sc{sub 1.8}O{sub 19}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, Rujun, E-mail: tangrj@suda.edu.cn, E-mail: yanghao@nuaa.edu.cn; Zhou, Hao; You, Wenlong

2016-08-22

The room-temperature multiferroic and magnetocapacitance (MC) effects of polycrystalline M-type hexaferrite BaFe{sub 10.2}Sc{sub 1.8}O{sub 19} have been investigated. The results show that the magnetic moments of insulating BaFe{sub 10.2}Sc{sub 1.8}O{sub 19} can be manipulated by the electric field at room temperature, indicating the existence of magnetoelectric coupling. Moreover, large MC effects are also observed around the room temperature. A frequency dependence analysis shows that the Maxwell-Wagner type magnetoresistance effect is the dominant mechanism for MC effects at low frequencies. Both the magnetoelectric-type and non-magnetoelectric-type spin-phonon couplings contribute to the MC effects at high frequencies with the former being the dominantmore » mechanism. The above results show that the hexaferrite BaFe{sub 10.2}Sc{sub 1.8}O{sub 19} is a room-temperature multiferroic material that can be potentially used in magnetoelectric devices.« less

Room temperature stretch forming of scale space shuttle external tank dome gores. Volume 1: Technical

NASA Technical Reports Server (NTRS)

Blunck, R. D.; Krantz, D. E.

1974-01-01

An account of activities and data gathered in the Room Temperature Stretch Forming of One-third Scale External Tank Bulkhead Gores for space shuttle study, and a tooling design and production cost study are reported. The following study phases are described: (1) the stretch forming of three approximately one-third scale external tank dome gores from single sheets of 2219-T37 aluminum alloy; (2) the designing of a full scale production die, including a determination of tooling requirements; and (3) the determination of cost per gore at the required production rates, including manufacturing, packaging, and shipping.

Quantitative Investigation of Room-Temperature Breakdown Effects in Pixelated TlBr Detectors

NASA Astrophysics Data System (ADS)

Koehler, Will; He, Zhong; Thrall, Crystal; O'Neal, Sean; Kim, Hadong; Cirignano, Leonard; Shah, Kanai

2014-10-01

Due to favorable material properties such as high atomic number (Tl: 81, Br: 35), high density ( 7.56 g/cm3), and a wide band gap (2.68 eV), thallium-bromide (TlBr) is currently under investigation for use as an alternative room-temperature semiconductor gamma-ray spectrometer. TlBr detectors can achieve less than 1% FWHM energy resolution at 662 keV, but these results are limited to stable operation at - 20°C. After days to months of room-temperature operation, ionic conduction causes these devices to fail. This work correlates the varying leakage current with alpha-particle and gamma-ray spectroscopic performances at various operating temperatures. Depth-dependent photopeak centroids exhibit time-dependent transient behavior, which indicates trapping sites form near the anode surface during room-temperature operation. After refabrication, similar performance and functionality of failed detectors returned.

Giant Room-Temperature Magnetodielectric Response in a MOF at 0.1 Tesla.

PubMed

Chen, Li-Hong; Guo, Jiang-Bin; Wang, Xuan; Dong, Xin-Wei; Zhao, Hai-Xia; Long, La-Sheng; Zheng, Lan-Sun

2017-11-01

A giant room-temperature magnetodielectric (MD) response upon the application of a small magnetic field is of fundamental importance for the practical application of a new generation of devices. Here, the giant room-temperature magnetodielectric response is demonstrated in the metal-organic framework (MOF) of [NH 2 (CH 3 ) 2 ] n [Fe III Fe II (1- x ) Ni II x (HCOO) 6 ] n (x ≈ 0.63-0.69) (1) with its MD coefficient remaining between -20% and -24% in the 300-410 K temperature range, even at 0.1 T. Because a room-temperature magnetodielectric response has never been observed in MOFs, the present work not only provides a new type of magnetodielectric material but also takes a solid step toward the practical application of MOFs in a new generation of devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Room-temperature creation and spin-orbit torque-induced manipulation of skyrmions in thin film

NASA Astrophysics Data System (ADS)

Yu, Guoqiang; Upadhyaya, Pramey; Li, Xiang; Li, Wenyuan; Im, Se Kwon K.; Fan, Yabin; Wong, Kin L.; Tserkovnyak, Yaroslav; Amiri, Pedram Khalili; Wang, Kang L.

Magnetic skyrmions, which are topologically protected spin texture, are promising candidates for ultra-low energy and ultra-high density magnetic data storage and computing applications1, 2. To date, most experiments on skyrmions have been carried out at low temperatures. The choice of materials available is limited and there is a lack of electrical means to control of skyrmions. Here, we experimentally demonstrate a method for creating skyrmion bubbles phase in the ferromagnetic thin film at room temperature. We further demonstrate that the created skyrmion bubbles can be manipulated by electric current. This room-temperature creation and manipulation of skyrmion in thin film is of particular interest for applications, being suitable for room-temperature operation and compatible with existing semiconductor manufacturing tools. 1. Nagaosa, N., Tokura, Y. Nature Nanotechnology 8, 899-911 (2013). 2. Fert, A., et al., Nature Nanotechnology 8, 152-156 (2013).

Room-temperature ferroelectricity of SrTiO{sub 3} films modulated by cation concentration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Fang; Zhang, Qinghua; Yang, Zhenzhong

2015-08-24

The room-temperature ferroelectricity of SrTiO{sub 3} is promising for oxide electronic devices controlled by multiple fields. An effective way to control the ferroelectricity is highly demanded. Here, we show that the off-centered antisite-like defects in SrTiO{sub 3} films epitaxially grown on Si (001) play the determinative role in the emergence of room-temperature ferroelectricity. The density of these defects changes with the film cation concentration sensitively, resulting in a varied coercive field of the ferroelectric behavior. Consequently, the room-temperature ferroelectricity of SrTiO{sub 3} films can be effectively modulated by tuning the temperature of metal sources during the molecular beam epitaxy growth.more » Such an easy and reliable modulation of the ferroelectricity enables the flexible engineering of multifunctional oxide electronic devices.« less

Room temperature structural and dielectric studies of Pb(Fe0.585Nb0.25W0.165)O3 solid solution

NASA Astrophysics Data System (ADS)

Nagaraja, T.; Dadami, Sunanda T.; Angadi, Basavaraj

2018-05-01

The perovskite A(B'B''B''')O3 structure Pb(Fe0.585Nb0.25W0.165)O3 (PFNW) multiferroic material was synthesized by single step solid state reaction method. The single phase was achieved at low temperature with optimized synthesis parameters as calcination (700°C/2hr) and sintering (800 °C /3hr). Single phase was confirmed by room temperature (RT) X-ray diffraction (XRD). The scanning electron microscopy (SEM) shows the uniform distribution of grains throughout the surface of PFNW and the energy dispersive X-ray spectroscopy (EDX) confirms the exact elemental composition as that of the experimental. Fourier transform infrared spectroscopy (FTIR) exhibits two absorption bands at 602 cm-1 and 1385 cm-1 corresponds to the bending and stretching vibrations of metal oxides. RT dielectric studies (dielectric constant, tanδ, AC conductivity) exhibits maximum values at lower frequency region and decreases as the frequency increases. Thesingle semicircular arc in RT impedance spectra (Nyquist plot)indicatesthe contribution to the conductivity is from grains only. Hence PFNW is a potential candidate for near room temperature applications.

Effects of storage conditions of Moringa oleifera seeds on its performance in coagulation.

PubMed

Katayon, S; Noor, M J Megat Mohd; Asma, M; Ghani, L A Abdul; Thamer, A M; Azni, I; Ahmad, J; Khor, B C; Suleyman, A M

2006-09-01

Moringa oleifera is a plant whose seeds have coagulation properties for treating water and wastewater. In this study the coagulation efficiency of Moringa oleifera kept in different storage conditions were studied. The Moringa oleifera seeds were stored at different conditions and durations; open container and closed container at room temperature (28 degrees C) and refrigerator (3 degrees C) for durations of 1, 3 and 5 months. Comparison between turbidity removal efficiency of Moringa oleifera kept in refrigerator and room temperature revealed that there was no significant difference between them. The Moringa oleifera kept in refrigerator and room temperature for one month showed higher turbidity removal efficiency, compared to those kept for 3 and 5 months, at both containers. The coagulation efficiency of Moringa oleifera was found to be dependent on initial turbidity of water samples. Highest turbidity removals were obtained for water with very high initial turbidity. In summary coagulation efficiency of Moringa oleifera was found independent of storage temperature and container, however coagulation efficiency of Moringa oleifera decreased as storage duration increased. In addition, Moringa oleifera can be used as a potential coagulant especially for very high turbidity water.

Influence of load and temperature on tribological behaviour of electroless Ni-P deposits

NASA Astrophysics Data System (ADS)

Kundu, S.; Das, S. K.; Sahoo, P.

2016-09-01

Electroless Ni-P coatings have shown tremendous potential as tribology material at room temperature. However, the performance of the same in high temperature field needs to be evaluated as investigation reveals the softening of most of the coating materials. In the current study, both as-deposited as well as heat treated samples are developed for the performance evaluation. Coatings are tested under different loads with a constant speed and at temperatures ranging from room temperature (R.T.) to 500°C. Tribological tests are carried out on a pin-on- disc tribotester by selecting a wear track diameter of 60 mm for 5 minutes. Wear is reported in the form of wear rate by following Archard's equation. The microstructure characterization of the coating is performed using SEM (Scanning Electron Microscopy), EDX (Energy Dispersive X-Ray Analysis) and XRD (X-Ray Diffraction Analysis). Coating is developed with phosphorous weight percentages around 9% on cylindrical mild steel samples and the deposition thickness is observed to be around 50 μm. The as-deposited coating is found to be amorphous in nature and hardness of the as-deposited coating is found to be around 585HV01. Friction coefficient increases initially with the increase in temperature from room temperature up to 100°C but thereafter gradually decrease with the increase in temperature. Initial increase in temperature (up to 100°C) provides higher rate of wear compared to room temperature but with further increase it drops in most of the cases. Wear rate increases with the increase in temperature but as it crosses or nears the phase transformation temperature (around 340°C), the scenario gets reversed. From X-ray diffraction analysis, it is found that coating is amorphous in as-deposited condition but transforms into a crystalline structure with heat treatment.

Fun and Interdisciplinary Daytime Astrophysical Activities

ERIC Educational Resources Information Center

Aroca, S. C.; Schiel, D.; Silva, C. C.

2008-01-01

The present article describes some activities performed with high-school students in the "Solar Physics" course developed in a Brazilian science centre. The topics of chemical composition, temperature and stellar evolution were taught in a room totally dedicated to study of the Sun, a solar room, designed with simple and inexpensive…

Study of NaI(Tl) scintillator cooled down to liquid nitrogen temperature

NASA Astrophysics Data System (ADS)

Sibczyński, P.; Moszyński, M.; Szczęśniak, T.; Czarnacki, W.

2012-11-01

Since early 50's NaI(Tl) scintillators have been commonly used in many branches of physics and industry due to their relatively low price, high light output and fair energy resolution. Through this period of time, both spectroscopic and luminescence properties of NaI(Tl) were measured at room temperature. In this work, the gamma spectrometry and the luminescence properties of the NaI(Tl) at LN2 temperature were studied. The gamma spectrometry was carried out with the light readout by avalanche photodiodes cooled down together with the crystal in the cryostat. It was observed that non-proportionality measured at LN2 temperature is significantly better than that at room temperature. The energy resolution of the NaI(Tl) at 662 keV measured at LN2 temperature was estimated to be 6.57%, comparable to that measured commonly at RT with photomultipliers. A decay time measurement of the NaI(Tl) at LN2 showed a slower decay of 736±10 ns.

A Stable Room-Temperature Luminescent Biphenylmethyl Radical.

PubMed

Ai, Xin; Chen, Yingxin; Feng, Yuting; Li, Feng

2018-03-05

There is only one family of room-temperature luminescent radicals, the triphenylmethyl radicals, to date. Herein, we synthesize a new stable room-temperature luminescent radical, (N-carbazolyl)bis(2,4,6-tirchlorophenyl)methyl radical (CzBTM), which has improved properties compared to the triphenylmethyl radicals. X-ray crystallography, electron paramagnetic resonance spectroscopy, and magnetic susceptibility measurements confirmed the radical structure. CzBTM shows room-temperature deep-red to near-infrared emission in various solutions. Both thermal and photo stability were significantly enhanced by the replacement of trichlorobenzene by the carbazole moiety. The electroluminescence results of CzBTM verify its potential application to circumvent the problem of triplet harvesting in traditional fluorescent OLEDs. A new family of stable luminescent radicals based on CzBTM is anticipated. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Collaborative Research: Polymeric Multiferroics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Shenqiang

2017-04-20

The goal of this project is to investigate room temperature magnetism and magnetoelectric coupling of polymeric multiferroics. A new family of molecular charge-transfer crystals has been emerged as a fascinating opportunity for the development of all-organic electrics and spintronics due to its weak hyperfine interaction and low spin-orbit coupling; nevertheless, direct observations of room temperature magnetic spin ordering have yet to be accomplished in organic charge-transfer solids. Furthermore, room temperature magnetoelectric coupling effect hitherto known multiferroics, is anticipated in organic donor-acceptor complexes because of magnetic field effects on charge-transfer dipoles, yet this is also unexplored. The PI seeks to fundamentalmore » understanding of the control of organic crystals to demonstrate and explore room temperature multiferroicity. The experimental results have been verified through the theoretical modeling.« less

Survival of Salmonella enterica serovar infantis on and within stored table eggs.

PubMed

Lublin, Avishai; Maler, Ilana; Mechani, Sara; Pinto, Riky; Sela-Saldinger, Shlomo

2015-02-01

Contaminated table eggs are considered a primary source of foodborne salmonellosis globally. Recently, a single clone of Salmonella enterica serovar Infantis emerged in Israel and became the predominant serovar isolated in poultry. This clone is currently the most prevalent strain in poultry and is the leading cause of salmonellosis in humans. Because little is known regarding the potential transmission of this strain from contaminated eggs to humans, the objective of this study was to evaluate the ability of Salmonella Infantis to survive on the eggshell or within the egg during cold storage or at room temperature. Salmonella cells (5.7 log CFU per egg) were inoculated on the surface of 120 intact eggs or injected into the egg yolk (3.7 log CFU per egg) of another 120 eggs. Half of the eggs were stored at 5.5 ± 0.3°C and half at room temperature (25.5 ± 0.1°C) for up to 10 weeks. At both temperatures, the number of Salmonella cells on the shell declined by 2 log up to 4 weeks and remained constant thereafter. Yolk-inoculated Salmonella counts at cold storage declined by 1 log up to 4 weeks and remained constant, while room-temperature storage supported the growth of the pathogen to a level of 8 log CFU/ml of total egg content, as early as 4 weeks postinoculation. Examination of egg content following surface inoculation revealed the presence of Salmonella in a portion of the eggs at both temperatures up to 10 weeks, suggesting that this strain can also penetrate through the shell and survive within the egg. These findings imply that Salmonella enterica serovar Infantis is capable of survival both on the exterior and interior of table eggs and even multiply inside the egg at room temperature. Our findings support the need for prompt refrigeration to prevent Salmonella multiplication during storage of eggs at room temperature.

Local observation of reverse-domain superconductivity in a superconductor-ferromagnet hybrid.

PubMed

Fritzsche, J; Moshchalkov, V V; Eitel, H; Koelle, D; Kleiner, R; Szymczak, R

2006-06-23

Nanoscale magnetic and superconducting properties of the superconductor-ferromagnet Nb/PbFe12O19 hybrid were studied as a function of applied magnetic fields. Low-temperature scanning laser microscopy (LTSLM) together with transport measurements were carried out in order to reveal local variations of superconductivity induced by the magnetic field template produced by the ferromagnetic substrate. Room temperature magnetic force microscopy (MFM) was performed and magnetization curves were taken at room and low temperature to investigate the magnetic properties of the hybrid. Comparative analysis of the LTSLM and the MFM images has convincingly demonstrated the presence of the reverse-domain superconductivity.

Aging of ceramic carbonized hydroxyapatite at room temperature

NASA Astrophysics Data System (ADS)

Tkachenko, M. V.; Kamzin, A. S.

2016-08-01

The process of aging of ceramic carbonized hydroxyapatite (CHA) produced in a dry carbon dioxide atmosphere at temperatures of 800-1200°C has been studied by chemical and X-ray structural analysis, infrared spectroscopy, and scanning electron microscopy methods. The phase composition and structure of initial prepared ceramics samples and those aged for a year have been compared. It has been shown that relaxation of internal stresses occurring during pressed sample sintering causes plastic deformation of crystallites at room temperature, accompanied by redistribution of carbonate ions between A1, A2, B1, and B2 sites and CHA decomposition with the formation of CaO separations.

Static high pressure studies on Nd and Sc

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akella, J.; Xu, J.; Smith, G.S.

1985-06-24

We have investigated the crystal structural transformations in neodymium and scandium up to 4.0 GPa pressure and at room temperature, in a diamond-anvil high pressure apparatus. Nd has a double hexagonal-close packed (dhcp) structure at ambient pressure and temperature. Then it transforms to a face-centered cubic (fcc) structure at 3.8 GPa, which further transforms to a triple hexagonal-close packed structure (thcp) at about 18.0 GPa. In scandium we observed only one transformation from the hexagonal-close packed (hcp) structure at room temperature to a tetragonal structure. This transformation occurs between 19.0 and 23.2 GPa pressure.

A multi-state synthetic ferrimagnet with controllable switching near room temperature

NASA Astrophysics Data System (ADS)

Franco, A. F.; Landeros, P.

2018-06-01

Ferrite composites with temperature-induced magnetization reversal, and synthetic ferrimagnets and antiferromagnets have been of great interest to the scientific community due to their uncommon thermal properties and potential applications in magnetic storage, spintronic devices, and several other fields. One of the advantages of these structures is the strong antiferromagnetic coupling, which stabilizes the magnetization state and gives access to interesting static and dynamical magnetic behaviors. Some of their drawbacks lie in that it is difficult to induce temperature-induced magnetization reversal at room temperature in composites, and that the strong interaction makes it difficult to induce a parallel magnetization state (and thus a high magnetic moment). In this work, we study numerically the magnetization behaviour of a Cu(1 0 0)/Ni/Pt/[Co/Pt]4 synthetic ferrimagnet and show that is possible to revert the sign of its magnetization by varying the temperature in ranges around room temperature. We also show that the four parallel and antiparallel magnetization states are stable at temperatures up to 360 K, and demonstrate that it is possible to change deterministically between these states by increasing the temperature of the device and/or applying a magnetic field, showcasing simultaneous non-hysteretic and hysteretic switching processes induced by temperature. Thus, this structure opens the possibility to have reconfigurable magnetic devices with multiple purposes based on the nature of the different switching events and the interplay between them.

Enhanced Hot Tensile Ductility of Mg-3Al-1Zn Alloy Thin-Walled Tubes Processed Via a Combined Severe Plastic Deformation

NASA Astrophysics Data System (ADS)

Fata, A.; Eftekhari, M.; Faraji, G.; Mosavi Mashhadi, M.

2018-04-01

In the current study, combined parallel tubular channel angular pressing (PTCAP) and tube backward extrusion (TBE), as a recently developed severe plastic deformation (SPD) method, were applied at 300 °C on a commercial Mg-3Al-1Zn alloy tubes to achieve an ultrafine grained structure. Then, the microstructure, hardness, tensile properties, and fractography evaluations were done at room temperature on the SPD-processed samples. Also, to study the hot tensile ductility of the SPD-processed samples, tensile testing was performed at an elevated temperature of 400 °C, and then, the fractured surface of the tensile samples was studied. It was observed that a bimodal microstructure, with large gains surrounded by many tiny ones, was created in the sample processed by PTCAP followed by TBE. This microstructure led to reach higher hardness and higher strength at room temperature and also led to reach very high elongation to failure ( 181%) at 400 °C. Also, the value of elongation to failure for this sample was 14.1% at room temperature. The fractographic SEM images showed the occurrence of predominately ductile fracture in the samples pulled at 400 °C. This was mostly due to the nucleation of microvoids and their subsequent growth and coalescence with each other.

Mössbauer and magnetic studies of surfactant mediated Ca-Mg doped ferrihydrite nanoparticles.

PubMed

Layek, Samar; Mohapatra, M; Anand, S; Verma, H C

2013-03-01

Ultrafine (2-5 nm) particles of amorphous Ca-Mg co-doped ferrihydrite have been synthesized by surfactant mediated co-precipitation method. The evolution of the amorphous ferrihydrite by Ca-Mg co-doping is quite different from our earlier investigations on individual doping of Ca and Mg. Amorphous phase of ferrihydrite for the present study has been confirmed by X-ray diffraction (XRD) and Mössbauer spectroscopy at room temperature and low temperatures (40 K and 20 K). Hematite nanoparticles with crystallite size about 8, 38 and 70 nm were obtained after annealing the as-prepared samples at 400, 600 and 800 degrees C respectively in air atmosphere. Superparamagnetism has been found in 8 nm sized hematite nanoparticles which has been confirmed from the magnetic hysteresis loop with zero remanent magnetization and coercive field and also from the superparamagnetic doublet of its room temperature Mössbauer spectrum. The magnetic properties of the 38 and 70 nm sized particles have been studied by room temperature magnetic hysteresis loop measurements and Mössbauer spectroscopy. The coercive field in these hematite nanoparticles increases with increasing particle size. Small amount of spinel MgFe2O4 phase has been detected in the 800 degrees C annealed sample.

Enhanced Hot Tensile Ductility of Mg-3Al-1Zn Alloy Thin-Walled Tubes Processed Via a Combined Severe Plastic Deformation

NASA Astrophysics Data System (ADS)

Fata, A.; Eftekhari, M.; Faraji, G.; Mosavi Mashhadi, M.

2018-05-01

In the current study, combined parallel tubular channel angular pressing (PTCAP) and tube backward extrusion (TBE), as a recently developed severe plastic deformation (SPD) method, were applied at 300 °C on a commercial Mg-3Al-1Zn alloy tubes to achieve an ultrafine grained structure. Then, the microstructure, hardness, tensile properties, and fractography evaluations were done at room temperature on the SPD-processed samples. Also, to study the hot tensile ductility of the SPD-processed samples, tensile testing was performed at an elevated temperature of 400 °C, and then, the fractured surface of the tensile samples was studied. It was observed that a bimodal microstructure, with large gains surrounded by many tiny ones, was created in the sample processed by PTCAP followed by TBE. This microstructure led to reach higher hardness and higher strength at room temperature and also led to reach very high elongation to failure ( 181%) at 400 °C. Also, the value of elongation to failure for this sample was 14.1% at room temperature. The fractographic SEM images showed the occurrence of predominately ductile fracture in the samples pulled at 400 °C. This was mostly due to the nucleation of microvoids and their subsequent growth and coalescence with each other.

Advanced Control Surface Seal Development for Future Space Vehicles

NASA Technical Reports Server (NTRS)

DeMange, J. J.; Dunlap, P. H., Jr.; Steinetz, B. M.

2004-01-01

NASA s Glenn Research Center (GRC) has been developing advanced high temperature structural seals since the late 1980's and is currently developing seals for future space vehicles as part of the Next Generation Launch Technology (NGLT) program. This includes control surface seals that seal the edges and hinge lines of movable flaps and elevons on future reentry vehicles. In these applications, the seals must operate at temperatures above 2000 F in an oxidizing environment, limit hot gas leakage to protect underlying structures, endure high temperature scrubbing against rough surfaces, and remain flexible and resilient enough to stay in contact with sealing surfaces for multiple heating and loading cycles. For this study, three seal designs were compared against the baseline spring tube seal through a series of compression tests at room temperature and 2000 F and flow tests at room temperature. In addition, canted coil springs were tested as preloaders behind the seals at room temperature to assess their potential for improving resiliency. Addition of these preloader elements resulted in significant increases in resiliency compared to the seals by themselves and surpassed the performance of the baseline seal at room temperature. Flow tests demonstrated that the seal candidates with engineered cores had lower leakage rates than the baseline spring tube design. However, when the seals were placed on the preloader elements, the flow rates were higher as the seals were not compressed as much and therefore were not able to fill the groove as well. High temperature tests were also conducted to asses the compatibility of seal fabrics against ceramic matrix composite (CMC) panels anticipated for use in next generation launch vehicles. These evaluations demonstrated potential bonding issues between the Nextel fabrics and CMC candidates.

Quality Detection of Litchi Stored in Different Environments Using an Electronic Nose

PubMed Central

Xu, Sai; Lü, Enli; Lu, Huazhong; Zhou, Zhiyan; Wang, Yu; Yang, Jing; Wang, Yajuan

2016-01-01

The purpose of this paper was to explore the utility of an electronic nose to detect the quality of litchi fruit stored in different environments. In this study, a PEN3 electronic nose was adopted to test the storage time and hardness of litchi that were stored in three different types of environment (room temperature, refrigerator and controlled-atmosphere). After acquiring data about the hardness of the sample and from the electronic nose, linear discriminant analysis (LDA), canonical correlation analysis (CCA), BP neural network (BPNN) and BP neural network-partial least squares regression (BPNN-PLSR), were employed for data processing. The experimental results showed that the hardness of litchi fruits stored in all three environments decreased during storage. The litchi stored at room temperature had the fastest rate of decrease in hardness, followed by those stored in a refrigerator environment and under a controlled-atmosphere. LDA has a poor ability to classify the storage time of the three environments in which litchi was stored. BPNN can effectively recognize the storage time of litchi stored in a refrigerator and a controlled-atmosphere environment. However, the BPNN classification of the effect of room temperature storage on litchi was poor. CCA results show a significant correlation between electronic nose data and hardness data under the room temperature, and the correlation is more obvious for those under the refrigerator environment and controlled-atmosphere environment. The BPNN-PLSR can effectively predict the hardness of litchi under refrigerator storage conditions and a controlled-atmosphere environment. However, the BPNN-PLSR prediction of the effect of room temperature storage on litchi and global environment storage on litchi were poor. Thus, this experiment proved that an electronic nose can detect the quality of litchi under refrigeratored storage and a controlled-atmosphere environment. These results provide a useful reference for future studies on nondestructive and intelligent monitoring of fruit quality. PMID:27338391

High temperature dielectric studies of indium-substituted NiCuZn nanoferrites

NASA Astrophysics Data System (ADS)

Hashim, Mohd.; Raghasudha, M.; Shah, Jyoti; Shirsath, Sagar E.; Ravinder, D.; Kumar, Shalendra; Meena, Sher Singh; Bhatt, Pramod; Alimuddin; Kumar, Ravi; Kotnala, R. K.

2018-01-01

In this study, indium (In3+)-substituted NiCuZn nanostructured ceramic ferrites with a chemical composition of Ni0.5Cu0.25Zn0.25Fe2-xInxO4 (0.0 ≤ x ≤ 0.5) were prepared by chemical synthesis involving sol-gel chemistry. Single phased cubic spinel structure materials were prepared successfully according to X-ray diffraction and transmission electron microscopy analyses. The dielectric properties of the prepared ferrites were measured using an LCR HiTester at temperatures ranging from room temperature to 300 °C at different frequencies from 102 Hz to 5 × 106 Hz. The variations in the dielectric parameters ε‧ and (tanδ) with temperature demonstrated the frequency- and temperature-dependent characteristics due to electron hopping between the ions. The materials had low dielectric loss values in the high frequency range at all temperatures, which makes them suitable for high frequency microwave applications. A qualitative explanation is provided for the dependences of the dielectric constant and dielectric loss tangent on the frequency, temperature, and composition. Mӧssbauer spectroscopy was employed at room temperature to characterize the magnetic behavior.

Direct synthesis of ultrafine tetragonal BaTiO3 nanoparticles at room temperature

PubMed Central

2011-01-01

A large quantity of ultrafine tetragonal barium titanate (BaTiO3) nanoparticles is directly synthesized at room temperature. The crystalline form and grain size are checked by both X-ray diffraction and transmission electron microscopy. The results revealed that the perovskite nanoparticles as fine as 7 nm have been synthesized. The phase transition of the as-prepared nanoparticles is investigated by the temperature-dependent Raman spectrum and shows the similar tendency to that of bulk BaTiO3 materials. It is confirmed that the nanoparticles have tetragonal phase at room temperature. PMID:21781339

Room-temperature magnetoelectric multiferroic thin films and applications thereof

DOEpatents

Katiyar, Ram S; Kuman, Ashok; Scott, James F.

2014-08-12

The invention provides a novel class of room-temperature, single-phase, magnetoelectric multiferroic (PbFe.sub.0.67W.sub.0.33O.sub.3).sub.x (PbZr.sub.0.53Ti.sub.0.47O.sub.3).sub.1-x (0.2.ltoreq.x.ltoreq.0.8) (PFW.sub.x-PZT.sub.1-x) thin films that exhibit high dielectric constants, high polarization, weak saturation magnetization, broad dielectric temperature peak, high-frequency dispersion, low dielectric loss and low leakage current. These properties render them to be suitable candidates for room-temperature multiferroic devices. Methods of preparation are also provided.

Room temperature ferromagnetic and semiconducting properties of graphene adsorbed with cobalt oxide using electrochemical method

NASA Astrophysics Data System (ADS)

Park, Chang-Soo; Lee, Kyung Su; Chu, Dongil; Lee, Juwon; Shon, Yoon; Kim, Eun Kyu

2017-12-01

We report the room temperature ferromagnetic properties of graphene adsorbed by cobalt oxide using electrochemical method. The cobalt oxide doping onto graphene was carried out in 0.1 M LiCoO2/DI-water solution. The doped graphene thin film was determined to be a single layer from Raman analysis. The CoO doped graphene has a clear ferromagnetic hysteresis at room temperature and showed a remnant magnetization, 128.2 emu/cm3. The temperature dependent conductivity of the adsorbed graphene showed the semiconducting behavior and a band gap opening of 0.12 eV.

Effect of short-term room temperature storage on the microbial community in infant fecal samples.

PubMed

Guo, Yong; Li, Sheng-Hui; Kuang, Ya-Shu; He, Jian-Rong; Lu, Jin-Hua; Luo, Bei-Jun; Jiang, Feng-Ju; Liu, Yao-Zhong; Papasian, Christopher J; Xia, Hui-Min; Deng, Hong-Wen; Qiu, Xiu

2016-05-26

Sample storage conditions are important for unbiased analysis of microbial communities in metagenomic studies. Specifically, for infant gut microbiota studies, stool specimens are often exposed to room temperature (RT) conditions prior to analysis. This could lead to variations in structural and quantitative assessment of bacterial communities. To estimate such effects of RT storage, we collected feces from 29 healthy infants (0-3 months) and partitioned each sample into 5 portions to be stored for different lengths of time at RT before freezing at -80 °C. Alpha diversity did not differ between samples with storage time from 0 to 2 hours. The UniFrac distances and microbial composition analysis showed significant differences by testing among individuals, but not by testing between different time points at RT. Changes in the relative abundance of some specific (less common, minor) taxa were still found during storage at room temperature. Our results support previous studies in children and adults, and provided useful information for accurate characterization of infant gut microbiomes. In particular, our study furnished a solid foundation and justification for using fecal samples exposed to RT for less than 2 hours for comparative analyses between various medical conditions.

46 CFR 111.01-15 - Temperature ratings.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS... is assumed for all rotating electrical machinery in boiler rooms, engine rooms, auxiliary machinery...-rotating electrical equipment in boiler rooms, in engine rooms, in auxiliary machinery rooms, and on...

46 CFR 111.01-15 - Temperature ratings.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS... is assumed for all rotating electrical machinery in boiler rooms, engine rooms, auxiliary machinery...-rotating electrical equipment in boiler rooms, in engine rooms, in auxiliary machinery rooms, and on...

46 CFR 111.01-15 - Temperature ratings.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS... is assumed for all rotating electrical machinery in boiler rooms, engine rooms, auxiliary machinery...-rotating electrical equipment in boiler rooms, in engine rooms, in auxiliary machinery rooms, and on...

The effect of temperature on the germination of Melocactus violaceus Pfeiff. (Cactaceae), a threatened species in restinga sandy coastal plain of Brazil.

PubMed

Zamith, Luiz R; Cruz, Denise D; Richers, Bárbara T T

2013-01-01

Melocactus violaceus is an endangered species due to habitat destruction and the overcollection of this species for ornamental use. The aim of this study was to test the effect of different temperatures on the germination of M. violaceus. Three treatments were conducted: a constant temperature of 25ºC, a 20-35ºC alternating temperature, both inside germination chamber, and an alternating temperature under room temperature (mean temperature ranged from 25-37ºC). The final seed germination rates at the alternating temperature treatments were not significantly different (65% in the seed germinator and 62.5% at room condition). However, both treatments with alternating temperatures had significantly higher germination rates compared to the treatment kept at the constant temperature (8%). Our study showed that alternating temperatures between 20 and 37ºC provides satisfactory conditions to induce a high percentage of seed germination of M. violaceus, without the passage of seeds through the digestive tract of its natural disperser, the lizard Tropidurus torquatus. This condition contributes to efficiently producing seedlings that can be reintroduced into conservation areas or used as ornamentals that may help reduce the overcollection of the remaining native populations.

Self-locking threaded fasteners

DOEpatents

Glovan, Ronald J.; Tierney, John C.; McLean, Leroy L.; Johnson, Lawrence L.

1996-01-01

A threaded fastener with a shape memory alloy (SMA) coatings on its threads is disclosed. The fastener has special usefulness in high temperature applications where high reliability is important. The SMA coated fastener is threaded into or onto a mating threaded part at room temperature to produce a fastened object. The SMA coating is distorted during the assembly. At elevated temperatures the coating tries to recover its original shape and thereby exerts locking forces on the threads. When the fastened object is returned to room temperature the locking forces dissipate. Consequently the threaded fasteners can be readily disassembled at room temperature but remains securely fastened at high temperatures. A spray technique is disclosed as a particularly useful method of coating of threads of a fastener with a shape memory alloy.

Correlation of mechanical properties with metallurgical structure for 18Ni 200 grade maraging steel at room and cryogenic temperatures

NASA Technical Reports Server (NTRS)

Wagner, J. A.

1991-01-01

An extensive metallurgical study is presented which is intended to explain variations in the mechanical properties of Ni18 200 grade maraging steel in various product forms and orientations. Fracture toughness and Charpy impact values are found to decrease with decreasing temperature and be dependent on product form, specimen orientation, and metallurgical condition. Fatigue crack growth rates are dependent on temperature only. Fractographic analysis reveals that the decrease in toughness at -170 C is not associated with cleavage-type fracture morphology. Those specimens exhibiting low fracture toughness at room temperature or -170 C are found to have a significantly larger number of titanium-rich particles associated with dimple formation on the fracture surface.

Synthesis of isoflavones by room-temperature nickel-catalyzed cross-couplings of 3-iodo(bromo)chromones with arylzincs.

PubMed

Zhang, Zunting; Qiao, Jinfeng; Wang, Ding; Han, Ling; Ding, Ru

2014-05-01

A new concise, facile method for synthesis of isoflavones was accomplished in moderate to good yields for 3-iodochromones or 3-bromochromones and arylzinc bromides via Negishi cross-coupling reaction catalyzed by NiCl(2)/PPh(3) or NiCl(2)(PPh(3))(2) at room temperature. The Isoflavone core was synthesized in four steps in good yield, starting from commercially available 2-hydroxyacetophenone and aromatic bromide. Three steps of the procedure were carried out at room temperature.

Temperature autocontrol system for the coud%eacute; room of the 1.2 m telescope

NASA Astrophysics Data System (ADS)

Zhang, Jian-Hua

The setting up of temperature autocontrol system for the coudé room of the 1.2 m telescope at Yunnan Observatory and realizing the airflow autocirculation, purified the air, keeping the temperature in the coudé room constantly by autocontrol the heater, and then keeping the optical system in the best condition are introduced in this paper. The autocontrol system is designed and developed at the basis of having only the air circulator and the heater controlled by hand.

Advancing the Capabilities of an Authentic Ex Vivo Model of Primary Human Prostate Cancer

DTIC Science & Technology

2014-10-01

maintained the PTEN expression of the native tissues after 5 days in culture. Prostate-specific membrane antigen ( PSMA ) was detected in benign and malignant...room temperature 1 h room temperature 30 min room temperature Abcam, Cambridge, MA, USA p63 SMA CD68 PSMA Mouse monoclonal Mouse monoclonal Mouse...Prostate-specific membrane antigen ( PSMA ) was detected in benign and malignant glands as expected in both native tissue and in TSCs after 5 days.47

Directionally Solidified NiAl-Based Alloys Studied for Improved Elevated-Temperature Strength and Room-Temperature Fracture Toughness

NASA Technical Reports Server (NTRS)

Whittenberger, J. Daniel; Raj, Sai V.; Locci, Ivan E.; Salem, Jonathan A.

2000-01-01

Efforts are underway to replace superalloys used in the hot sections of gas turbine engines with materials possessing better mechanical and physical properties. Alloys based on the intermetallic NiAl have demonstrated potential; however, they generally suffer from low fracture resistance (toughness) at room temperature and from poor strength at elevated temperatures. Directional solidification of NiAl alloyed with both Cr and Mo has yielded materials with useful toughness and elevated-temperature strength values. The intermetallic alloy NiAl has been proposed as an advanced material to extend the maximum operational temperature of gas turbine engines by several hundred degrees centigrade. This intermetallic alloy displays a lower density (approximately 30-percent less) and a higher thermal conductivity (4 to 8 times greater) than conventional superalloys as well as good high-temperature oxidation resistance. Unfortunately, unalloyed NiAl has poor elevated temperature strength (approximately 50 MPa at 1027 C) and low room-temperature fracture toughness (about 5 MPa). Directionally solidified NiAl eutectic alloys are known to possess a combination of high elevated-temperature strength and good room-temperature fracture toughness. Research has demonstrated that a NiAl matrix containing a uniform distribution of very thin Cr plates alloyed with Mo possessed both increased fracture toughness and elevated-temperature creep strength. Although attractive properties were obtained, these alloys were formed at low growth rates (greater than 19 mm/hr), which are considered to be economically unviable. Hence, an investigation was warranted of the strength and toughness behavior of NiAl-(Cr,Mo) directionally solidified at faster growth rates. If the mechanical properties did not deteriorate with increased growth rates, directional solidification could offer an economical means to produce NiAl-based alloys commercially for gas turbine engines. An investigation at the NASA Glenn Research Center at Lewis Field was undertaken to study the effect of the directional solidification growth rate on the microstructure, room temperature fracture toughness, and strength at 1027 C of a Ni-33Al-31Cr-3Mo eutectic alloy. The directionally solidified rates varied between 7.6 and 508 millimeters per hour Essentially fault-free, alternating (Cr, Mo)/NiAl lamellar plate microstructures (left photograph) were formed during growth at and below 12.7 mm/hr, whereas cellular microstructures (right photograph) with the (Cr, Mo) phase in a radial spokelike pattern were developed at faster growth rates. The compressive strength at 1027 C continuously increased with increasing growth rate and did not indicate a maxima as was reported for directionally solidified Ni-33Al-34Cr. Surprisingly, samples with the lamellar plate microstructure (left photograph) possessed a room-temperature fracture toughness of approximately 12 MPa(sup square root of m), whereas all the alloys with a cellular microstructure had a toughness of about 17 MPa(sup square root of m). These results are significant since they clearly demonstrate that Ni-33Al-31Cr-3Mo can be directionally solidified at much faster growth rates without any observable deterioration in its mechanical properties. Thus, the potential to produce strong, tough NiAl-based eutectics at commercially acceptable growth rates exists. Additional testing and alloy optimization studies are underway.

Weather conditions influence the number of psychiatric emergency room patients

NASA Astrophysics Data System (ADS)

Brandl, Eva Janina; Lett, Tristram A.; Bakanidze, George; Heinz, Andreas; Bermpohl, Felix; Schouler-Ocak, Meryam

2017-12-01

The specific impact of weather factors on psychiatric disorders has been investigated only in few studies with inconsistent results. We hypothesized that meteorological conditions influence the number of cases presenting in a psychiatric emergency room as a measure of mental health conditions. We analyzed the number of patients consulting the emergency room (ER) of a psychiatric hospital in Berlin, Germany, between January 1, 2008, and December 31, 2014. A total of N = 22,672 cases were treated in the ER over the study period. Meteorological data were obtained from a publicly available data base. Due to collinearity among the meteorological variables, we performed a principal component (PC) analysis. Association of PCs with the daily number of patients was analyzed with autoregressive integrated moving average model. Delayed effects were investigated using Granger causal modeling. Daily number of patients in the ER was significantly higher in spring and summer compared to fall and winter (p < 0.001). Three PCs explained 76.8% percent of the variance with PC1 loading mostly on temperature, PC2 on cloudiness and low pressure, and PC3 on windiness. PC1 and PC2 showed strong association with number of patients in the emergency room (p < 0.010) indicating higher patient numbers on warmer and on cloudy days. Further, PC1, PC2, and PC3 predicted the number of patients presenting in the emergency room for up to 7 days (p < 0.050). A secondary analysis revealed that the effect of temperature on number of patients was mostly due to lower patient numbers on cold days. Although replication of our findings is required, our results suggest that weather influences the number of psychiatric patients consulting the emergency room. In particular, our data indicate lower patient numbers during very cold temperatures.

Weather conditions influence the number of psychiatric emergency room patients

NASA Astrophysics Data System (ADS)

Brandl, Eva Janina; Lett, Tristram A.; Bakanidze, George; Heinz, Andreas; Bermpohl, Felix; Schouler-Ocak, Meryam

2018-05-01

The specific impact of weather factors on psychiatric disorders has been investigated only in few studies with inconsistent results. We hypothesized that meteorological conditions influence the number of cases presenting in a psychiatric emergency room as a measure of mental health conditions. We analyzed the number of patients consulting the emergency room (ER) of a psychiatric hospital in Berlin, Germany, between January 1, 2008, and December 31, 2014. A total of N = 22,672 cases were treated in the ER over the study period. Meteorological data were obtained from a publicly available data base. Due to collinearity among the meteorological variables, we performed a principal component (PC) analysis. Association of PCs with the daily number of patients was analyzed with autoregressive integrated moving average model. Delayed effects were investigated using Granger causal modeling. Daily number of patients in the ER was significantly higher in spring and summer compared to fall and winter ( p < 0.001). Three PCs explained 76.8% percent of the variance with PC1 loading mostly on temperature, PC2 on cloudiness and low pressure, and PC3 on windiness. PC1 and PC2 showed strong association with number of patients in the emergency room ( p < 0.010) indicating higher patient numbers on warmer and on cloudy days. Further, PC1, PC2, and PC3 predicted the number of patients presenting in the emergency room for up to 7 days ( p < 0.050). A secondary analysis revealed that the effect of temperature on number of patients was mostly due to lower patient numbers on cold days. Although replication of our findings is required, our results suggest that weather influences the number of psychiatric patients consulting the emergency room. In particular, our data indicate lower patient numbers during very cold temperatures.

Correlation between Temperature-dependent Fatigue Resistance and Differential Scanning Calorimetry Analysis for 2 Contemporary Rotary Instruments.

PubMed

Arias, Ana; Macorra, José C; Govindjee, Sanjay; Peters, Ove A

2018-04-01

The aim of this study was to assess differences in cyclic fatigue (CF) life of contemporary heat-treated nickel-titanium rotary instruments at room and body temperatures and to document corresponding phase transformations. Forty Hyflex EDM (H-EDM) files (Coltene, Cuyahoga Falls, OH [#25/.08, manufactured by electrical discharge machining]) and 40 TRUShape (TS) files (Dentsply Tulsa Dental Specialties, Tulsa, OK [#25/.06v, manufactured by grinding and shape setting]) were divided into 2 groups (n = 20) for CF resistance tests in a water bath either at room (22°C ± 0.5°C) or body temperature (37°C ± 0.5°C). Instruments were rotated in a simulated canal (angle = 60°, radius = 3 mm, and center of the curvature 5 mm from the tip) until fracture occurred. The motor was controlled by an electric circuit that was interrupted after instrument fracture. The mean half-life and beta and eta Weibull parameters were determined and compared. Two instruments of each brand were subjected to differential scanning calorimetry (DSC). While TS instruments lasted significantly longer at room temperature (mean life = 234.7 seconds; 95% confidence interval [CI], 209-263.6) than at body temperature (mean life = 83.2 seconds; 95% CI, 76-91.1), temperature did not affect H-EDM behavior (room temperature mean life = 725.4 seconds; 95% CI, 658.8-798.8 and body temperature mean life = 717.9 seconds; 95% CI, 636.8-809.3). H-EDM instruments significantly outlasted TS instruments at both temperatures. At body temperature, TS was predominantly austenitic, whereas H-EDM was martensitic or in R-phase. TS was in a mixed austenitic/martensitic phase at 22°C, whereas H-EDM was in the same state as at 37°C. H-EDM had a longer fatigue life than TS, which showed a marked decrease in fatigue life at body temperature; neither the life span nor the state of the microstructure in the DSC differed for H-EDM between room or body temperature. Copyright © 2017 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Low-Temperature Photochemically Activated Amorphous Indium-Gallium-Zinc Oxide for Highly Stable Room-Temperature Gas Sensors.

PubMed

Jaisutti, Rawat; Kim, Jaeyoung; Park, Sung Kyu; Kim, Yong-Hoon

2016-08-10

We report on highly stable amorphous indium-gallium-zinc oxide (IGZO) gas sensors for ultraviolet (UV)-activated room-temperature detection of volatile organic compounds (VOCs). The IGZO sensors fabricated by a low-temperature photochemical activation process and exhibiting two orders higher photocurrent compared to conventional zinc oxide sensors, allowed high gas sensitivity against various VOCs even at room temperature. From a systematic analysis, it was found that by increasing the UV intensity, the gas sensitivity, response time, and recovery behavior of an IGZO sensor were strongly enhanced. In particular, under an UV intensity of 30 mW cm(-2), the IGZO sensor exhibited gas sensitivity, response time and recovery time of 37%, 37 and 53 s, respectively, against 750 ppm concentration of acetone gas. Moreover, the IGZO gas sensor had an excellent long-term stability showing around 6% variation in gas sensitivity over 70 days. These results strongly support a conclusion that a low-temperature solution-processed amorphous IGZO film can serve as a good candidate for room-temperature VOCs sensors for emerging wearable electronics.

Room-Temperature Multiferroics and Thermal Conductivity of 0.85BiFe1-2xTixMgxO3-0.15CaTiO3 Epitaxial Thin Films (x = 0.1 and 0.2).

PubMed

Zhang, Ji; Sun, Wei; Zhao, Jiangtao; Sun, Lei; Li, Lei; Yan, Xue-Jun; Wang, Ke; Gu, Zheng-Bin; Luo, Zhen-Lin; Chen, Yanbin; Yuan, Guo-Liang; Lu, Ming-Hui; Zhang, Shan-Tao

2017-08-02

Thin films of 0.85BiFe 1-2x Ti x Mg x O 3 -0.15CaTiO 3 (x = 0.1 and 0.2, abbreviated to C-1 and C-2, respectively) have been fabricated on (001) SrTiO 3 substrate with and without a conductive La 0.7 Sr 0.3 MnO 3 buffer layer. The X-ray θ-2θ and ϕ scans, atomic force microscopy, and cross-sectional transmission electron microscopy confirm the (001) epitaxial nature of the thin films with very high growth quality. Both the C-1 and C-2 thin films show well-shaped magnetization-magnetic field hysteresis at room temperature, with enhanced switchable magnetization values of 145.3 and 42.5 emu/cm 3 , respectively. The polarization-electric loops and piezoresponse force microscopy measurements confirm the room-temperature ferroelectric nature of both films. However, the C-1 films illustrate a relatively weak ferroelectric behavior and the poled states are easy to relax, whereas the C-2 films show a relatively better ferroelectric behavior with stable poled states. More interestingly, the room-temperature thermal conductivity of C-1 and C-2 films are measured to be 1.10 and 0.77 W/(m·K), respectively. These self-consistent multiferroic properties and thermal conductivities are discussed by considering the composition-dependent content and migration of Fe-induced electrons and/or charged point defects. This study not only provides multifunctional materials with excellent room-temperature magnetic, ferroelectric, and thermal conductivity properties but may also stimulate further work to develop BiFeO 3 -based materials with unusual multifunctional properties.

Effect of deep cryogenic temperature on silicon-on-insulator CMOS mismatch: A circuit designer’s perspective

NASA Astrophysics Data System (ADS)

Das, Kushal; Lehmann, Torsten

2014-07-01

The effect of ultra low operating temperature on mismatch among identically designed Silicon-on-Sapphire CMOS devices is investigated in detail from a circuit design view point. The evolution of transistor matching properties for different operating conditions at both room and 4.2 K temperature are presented. The statistical analysis reveals that mismatch at low temperature is effectively unrelated to that at room temperature, which disagrees with previously published literature. The measurement data was used to extract key transistor parameters and the consequence of temperature lowering on their respective variance is estimated. We find that standard deviation of the threshold-voltage mismatch deteriorates by a factor ∼2 at 4.2 K temperature. Similar to room temperature operation, mismatch at 4.2 K is bias point dependent and the degradation of matching at very low temperature depends to some extent on how the bias point shifts upon cooling.

Logistics and quality control for DNA sampling in large multicenter studies.

PubMed

Nederhand, R J; Droog, S; Kluft, C; Simoons, M L; de Maat, M P M

2003-05-01

To study associations between genetic variation and disease, large bio-banks need to be created in multicenter studies. Therefore, we studied the effects of storage time and temperature on DNA quality and quantity in a simulation experiment with storage up to 28 days frozen, at 4 degrees C and at room temperature. In the simulation experiment, the conditions did not influence the amount or quality of DNA to an unsatisfactory level. However, the amount of extracted DNA was decreased in frozen samples and in samples that were stored for > 7 days at room temperature. In a sample of patients from 24 countries of the EUROPA trial obtained by mail with transport times up to 1 month DNA yield and quality were adequate. From these results we conclude that transport of non-frozen blood by ordinary mail is usable and practical for DNA isolation for polymerase chain reaction in clinical and epidemiological studies.

Protocols for dry DNA storage and shipment at room temperature

PubMed Central

Ivanova, Natalia V; Kuzmina, Masha L

2013-01-01

The globalization of DNA barcoding will require core analytical facilities to develop cost-effective, efficient protocols for the shipment and archival storage of DNA extracts and PCR products. We evaluated three dry-state DNA stabilization systems: commercial Biomatrica® DNAstable® plates, home-made trehalose and polyvinyl alcohol (PVA) plates on 96-well panels of insect DNA stored at 56 °C and at room temperature. Controls included unprotected samples that were stored dry at room temperature and at 56 °C, and diluted samples held at 4 °C and at −20 °C. PCR and selective sequencing were performed over a 4-year interval to test the condition of DNA extracts. Biomatrica® provided better protection of DNA at 56 °C and at room temperature than trehalose and PVA, especially for diluted samples. PVA was the second best protectant after Biomatrica® at room temperature, whereas trehalose was the second best protectant at 56 °C. In spite of lower PCR success, the DNA stored at −20 °C yielded longer sequence reads and stronger signal, indicating that temperature is a crucial factor for DNA quality which has to be considered especially for long-term storage. Although it is premature to advocate a transition to DNA storage at room temperature, dry storage provides an additional layer of security for frozen samples, protecting them from degradation in the event of freezer failure. All three forms of DNA preservation enable shipment of dry DNA and PCR products between barcoding facilities. PMID:23789643

Acute impacts of extreme temperature exposure on emergency room admissions related to mental and behavior disorders in Toronto, Canada.

PubMed

Wang, Xiang; Lavigne, Eric; Ouellette-kuntz, Hélène; Chen, Bingshu E

2014-02-01

The purpose of this study was to assess the effects of extreme ambient temperature on hospital emergency room visits (ER) related to mental and behavioral illnesses in Toronto, Canada. A time series study was conducted using health and climatic data from 2002 to 2010 in Toronto, Canada. Relative risks (RRs) for increases in emergency room (ER) visits were estimated for specific mental and behavioral diseases (MBD) after exposure to hot and cold temperatures while using the 50th percentile of the daily mean temperature as reference. Poisson regression models using a distributed lag non-linear model (DLNM) were used. We adjusted for the effects of seasonality, humidity, day-of-the-week and outdoor air pollutants. We found a strong association between MBD ER visits and mean daily temperature at 28°C. The association was strongest within a period of 0-4 days for exposure to hot temperatures. A 29% (RR=1.29, 95% CI 1.09-1.53) increase in MBD ER vists was observed over a cumulative period of 7 days after exposure to high ambient temperature (99th percentile vs. 50th percentile). Similar associations were reported for schizophrenia, mood, and neurotic disorers. No significant associations with cold temperatures were reported. The ecological nature and the fact that only one city was investigated. Our findings suggest that extreme temperature poses a risk to the health and wellbeing for individuals with mental and behavior illnesses. Patient management and education may need to be improved as extreme temperatures may become more prevalent with climate change. © 2013 Elsevier B.V. All rights reserved.

Reversible photoinduced spectral change in Eu2O3 at room temperature

NASA Astrophysics Data System (ADS)

Mochizuki, Shosuke; Nakanishi, Tauto; Suzuki, Yuya; Ishi, Kimihiro

2001-12-01

When Eu2O3 powder compact and film are irradiated with ultraviolet (UV) laser light in a vacuum, their photoluminescence (PL) spectra change from a red sharp-line structure to a white broad band, which can be clearly seen with the naked eye. After removing the UV laser light, the white PL continues for more than several months at room temperature under room light, in spite of any changes of atmosphere. By irradiating with the same UV laser light at room temperature under O2 gas atmosphere, the original red PL state reappears. Such a reversible phenomenon may well yield materials for white-light-emitting devices and erasable optical storage.

Overnight storage of whole blood: a comparison of two designs of butane-1,4-diol cooling plates.

PubMed

van der Meer, Pieter F; Pietersz, Ruby N I

2007-11-01

Whole blood (WB) can be stored overnight before processing, provided that it is quickly cooled to room temperature (20-25 degrees C), for example, with butane-1,4-diol plates. A new design of cooling plates became available (CompoCool-WB, Fresenius HemoCare), where WB must be placed vertically against the plates, versus placing of WB under plates in the current version (Compocool). This study compared cooling efficiency and in vitro quality of plasma and of stored white cell (WBC)-reduced red cells (RBCs) from overnight-stored WB, cooled with either of the systems. Temperature curves following cooling with Compocool or CompoCool-WB were studied with a 25 percent glycerol solution as simulated WB. WB from voluntary donors was cooled with Compocool or CompoCool-WB, stored overnight at room temperature, centrifuged, and separated into components. WBC-reduced RBCs in SAGM were stored until Day 42 with measurement of in vitro parameters (n=23/group). Simulated WB reached a temperature of less than 25 degrees C after 2:15+/-1:04 hours for Compocool versus 1:39+/-0:38 hours for CompoCool-WB (p=0.02). On Day 35, RBCs had a hemolysis of 0.3+/-0.2 percent in both groups, and ATP levels were 3.3+/-0.5 and 3.6+/-0.5 micromol per g hemoglobin for Compocool and CompoCool-WB, respectively (not significant). Factor VIII content in plasma was 1.05+/-0.25 and 0.97+/-0.18 IU per mL for Compocool and CompoCool-WB, respectively. WB can be cooled to room temperature within 2 hours with both Compocool and CompoCool-WB butane-1,4-diol plates, improving temperature uniformity in WB donations. Application of either design for overnight storage of WB at room temperature had no adverse effects on the composition of subsequently prepared blood components.

The reduction and oxidation of ceria: A natural abundance triple oxygen isotope perspective

NASA Astrophysics Data System (ADS)

Hayles, Justin; Bao, Huiming

2015-06-01

Ceria (CeO2) is a heavily studied material in catalytic chemistry for use as an oxygen storage medium, oxygen partial pressure regulator, fuel additive, and for the production of syngas, among other applications. Ceria powders are readily reduced and lose structural oxygen when subjected to low pO2 and/or high temperature conditions. Such dis-stoichiometric ceria can then re-oxidize under higher pO2 and/or lower temperature by incorporating new oxygen into the previously formed oxygen site vacancies. Despite extensive studies on ceria, the mechanisms for oxygen adsorption-desorption, dissociation-association, and diffusion of oxygen species on ceria surface and within the crystal structure are not well known. We predict that a large kinetic oxygen isotope effect should accompany the release and incorporation of ceria oxygen. As the first attempt to determine the existence and the degree of the isotope effect, this study focuses on a set of simple room-temperature re-oxidation experiments that are also relevant to a laboratory procedure using ceria to measure the triple oxygen isotope composition of CO2. Triple-oxygen-isotope labeled ceria powders are heated at 700 °C and cooled under vacuum prior to exposure to air. By combining results from independent experimental sets with different initial oxygen isotope labels and using a combined mass-balance and triangulation approach, we have determined the isotope fractionation factors for both high temperature reduction in vacuum (⩽10-4 mbar) and room temperature re-oxidation in air. Results indicate that there is a 1.5‰ ± 0.8‰ increase in the δ18O value of ceria after being heated in vacuum at 700 °C for 1 h. When the vacuum is broken at room temperature, the previously heated ceria incorporates 3-19% of its final structural oxygen from air, with a δ18O value of 2.1-4.1+7.7 ‰ for the incorporated oxygen. The substantial incorporation of oxygen from air supports that oxygen mobility is high in vacancy-rich ceria during re-oxidation at room temperature. The quantified oxygen isotope fractionation factors are consistent with the direct involvement of O2 in the rate limiting step for ceria reoxidation in air at room temperature. While additional parameters may reduce some of the uncertainties in our approach, this study demonstrates that isotope effects can be an encouraging tool for studying oxygen transport kinetics in ceria and other oxides. In addition, our finding warns of the special cares and limits in using ceria as an exchange medium for laboratory triple oxygen isotope analysis of CO2 or other oxygen-bearing gases.

Method of solution preparation of polyolefin class polymers for electrospinning processing included

NASA Technical Reports Server (NTRS)

Rabolt, John F. (Inventor); Givens, Steven R. (Inventor); Lee, Keun-Hyung (Inventor)

2011-01-01

A process to make a polyolefin fiber which has the following steps: mixing at least one polyolefin into a solution at room temperature or a slightly elevated temperature to form a polymer solution and electrospinning at room temperature said polymer solution to form a fiber.

Room temperature synthesis of biodiesel using sulfonated graphitic carbon nitride

EPA Science Inventory

Sulfonation of graphitic carbon nitride (g-CN) affords a polar and strongly acidic catalyst, Sg-CN, which displays unprecedented reactivity and selectivity in biodiesel synthesis and esterification reactions at room temperature.

Room temperature synthesis of biodiesel using sulfonated graphitic carbon nitride

DOE PAGES

Baig, R. B. Nasir; Verma, Sanny; Nadagouda, Mallikarjuna N.; ...

2016-12-19

Sulfonation of graphitic carbon nitride (g-CN) affords a polar and strongly acidic catalyst, Sg-CN, which displays unprecedented reactivity and selectivity in biodiesel synthesis and esterification reactions at room temperature.

Low temperature electrical properties of some Pb-free solders

NASA Astrophysics Data System (ADS)

Kisiel, Ryszard; Pekala, Marek

2006-03-01

The electronic industry is engaged in developing Pb-free technologies for more than ten years. However till now not all properties of new solders are described. The aim of the paper is to present some electrical properties of new series of Pb-free solders (eutectic SnAg, near eutectic SnAgCu with and without Bi) in low temperature ranges 10 K to 273K. The following parameters were analyzed: electrical resistivity, temperature coefficient of resistance and thermoelectric power. The electrical resistivity at temperatures above 50 K is a monotonically rising function of temperature for Pb-free solders studied. The electrical resistivity of the Bi containing alloys is higher as compared to the remaining ones. The thermoelectric power values at room temperature are about -8 μV/K to -6 μV/K for Pb-free solders studied, being higher as compared to typical values -3 μVK of SnPb solder. The relatively low absolute values as well as the smooth and weak temperature variation of electrical resistivity in lead free solders enable the possible low temperature application. The moderate values of thermoelectric power around and above the room temperature show that when applying the solders studied the temperature should be kept as uniform as possible, in order to avoid spurious or noise voltages.

Simulation of effects of direction and air flow speed on temperature distribution in the room covered by various roof materials

NASA Astrophysics Data System (ADS)

Sukanto, H.; Budiana, E. P.; Putra, B. H. H.

2016-03-01

The objective of this research is to get a comparison of the distribution of the room temperature by using three materials, namely plastic-rubber composite, clay, and asbestos. The simulation used Ansys Fluent to get the temperature distribution. There were two conditions in this simulations, first the air passing beside the room and second the air passing in front of the room. Each condition will be varied with the air speed of 1 m/s, 2 m/s, 3 m/s, 4 m/s, 5 m/s for each material used. There are three heat transfers in this simulation, namely radiation, convection, and conduction. Based on the ANSI/ ASHRAE Standard 55-2004, the results of the simulation showed that the best temperature distribution was the roof of plastic-rubber composites.

Aspects of fracture mechanics in cryogenic model design. Part 2: NTF materials

NASA Technical Reports Server (NTRS)

Newman, J. C., Jr.; Lisagor, W. B.

1983-01-01

Results of fatigue crack growth and fracture toughness tests conducted on three candidate materials are presented. Fatigue crack growth and fracture toughness tests were conducted on NITRONIC 40 at room temperature and -275 F. Fracture toughness tests were also conducted on Vascomax 200 and 250 maraging steel from room temperature to -320 F. NITRONIC 40 was used to make the Pathfinder 1 model. The fatigue crack growth rate tests were conducted at room temperature and -275 F on three-point notch bend specimens. The fracture toughness tests on the as received and stress relieved materials at -275 F were conducted on the center crack tension specimens. Toughness tests were also conducted on Vascomax CVM-200 and CVM-250 maraging steel from room temperature to -320 F using round and rectangular compact specimens.

Room temperature synthesis of agarose/sol-gel glass pieces with tailored interconnected porosity.

PubMed

Cabañas, M V; Peña, J; Román, J; Vallet-Regí, M

2006-09-01

An original shaping technique has been applied to prepare porous bodies at room temperature. Agarose, a biodegradable polysaccharide, was added as binder of a sol-gel glass in powder form, yielding an easy to mold paste. Interconnected tailored porous bodies can be straightforwardly prepared by pouring the slurry into a polymeric scaffold, previously designed by stereolitography, which is subsequently eliminated by alkaline dissolution at room temperature. The so obtained pieces behave like a hydrogel with an enhanced consistency that makes them machinable and easy to manipulate. These materials generate an apatite-like layer when immersed in a simulated body fluid, indicating a potential in vivo bioactivity. The proposed method can be applied to different powdered materials to produce pieces, at room temperature, with various shapes and sizes and with tailored interconnected porosity.

Statistical study of the reliability of oxide-defined stripe cw lasers of (AlGa)As

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ettenberg, M.

1979-03-01

In this report, we describe a statistical study of the reliability of oxide-defined stripe-contact cw injection lasers of (AlGa)As. These devices have one facet coated with Al/sub 2/O/sub 3/ and one facet coated with an Al/sub 2/O/sub 3//Si dichroic reflector; the lasers are optimized for cw low-threshold currents at room temperature, with values typically about 50 mA. Lifetests were carried out at 70 /sup 0/C ambient, in the cw mode of operation with about 5 mW output. Previous lifetests showed that the degradation rate followed a 0.95-eV activation energy so the 70 /sup 0/C environment provides a degradation acceleration factormore » of 190 over that at room temperature. We have found that the device failures follow a log-normal distribution, characterized by a mean time before failure of 4200 h and a standard deviation of 1.3. This corresponds to a mean time to failure (MTTF) of 10/sup 6/ h at room temperature. Failure is defined here as the inability of the device to emit 1 mW of stimulated cw output at 70 /sup 0/C, and assumes that optical feedback will be employed to adjust the laser current during operation. If a constant-current drive is envisioned, the failures for a 3-dB drop in light output also follow a log-normal distribution with a similar slope (standard deviation=1.1) and a MTTF of 2000 h at 70 /sup 0/C (500 000 h at room temperature). The failures were found to be mainly due to bulk gradual degradation and not facet or contact failure. Careful study of lasers before and after lifetest showed a significant increase in contact thermal resistance. However, this increase accounts for only a small portion of the nearly 70% increase in room-temperature cw threshold after failure at 70 /sup 0/C. After failure at 70 /sup 0/C, we also noted a degradation in the near-field and associated far-field pattern of the laser.« less

Substrate effects on photoluminescence and low temperature phase transition of methylammonium lead iodide hybrid perovskite thin films

NASA Astrophysics Data System (ADS)

Shojaee, S. A.; Harriman, T. A.; Han, G. S.; Lee, J.-K.; Lucca, D. A.

2017-07-01

We examine the effects of substrates on the low temperature photoluminescence (PL) spectra and phase transition in methylammonium lead iodide hybrid perovskite (CH3NH3PbI3) thin films. Structural characterization at room temperature with X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy indicated that while the chemical structure of films deposited on glass and quartz was similar, the glass substrate induced strain in the perovskite films and suppressed the grain growth. The luminescence response and phase transition of the perovskite thin films were studied by PL spectroscopy. The induced strain was found to affect both the room temperature and low temperature PL spectra of the hybrid perovskite films. In addition, it was found that the effects of the glass substrate inhibited a tetragonal to orthorhombic phase transition such that it occurred at lower temperatures.

Recommendations to Improve Employee Thermal Comfort When Working in 40°F Refrigerated Cold Rooms.

PubMed

Ceballos, Diana; Mead, Kenneth; Ramsey, Jessica

2015-01-01

Cold rooms are commonly used for food storage and preparation, and are usually kept around 40°F following food safety guidelines. Some food preparation employees may spend 8 or more hours inside cold rooms. These employees may not be aware of the risks associated with mildly cold temperatures, dampness, and limited ventilation. We performed an evaluation of cold rooms at an airline catering facility because of concerns with exposure to cold temperatures. We spoke with and observed employees in two cold rooms, reviewed daily temperature logs, evaluated employee's physical activity, work/rest schedule, and protective clothing. We measured temperature, percent relative humidity, and air velocities at different work stations inside the cold rooms. We concluded that thermal comfort concerns perceived by cold room employees may have been the result of air drafts at their workstations, insufficient use of personal protective equipment due to dexterity concerns, work practices, and lack of knowledge about good health and safety practices in cold rooms. These moderately cold work conditions with low air velocities are not well covered in current occupational health and safety guidelines, and wind chill calculations do not apply. We provide practical recommendations to improve thermal comfort of cold room employees. Engineering control recommendations include the redesigning of air deflectors and installing of suspended baffles. Administrative controls include the changing out of wet clothing, providing hand warmers outside of cold rooms, and educating employees on cold stress. We also recommended providing more options on personal protective equipment. However, there is a need for guidelines and educational materials tailored to employees in moderately cold environments to improve thermal comfort and minimize health and safety problems.

Recommendations to Improve Employee Thermal Comfort When Working in 40°F Refrigerated Cold Rooms

PubMed Central

Ceballos, Diana; Mead, Kenneth; Ramsey, Jessica

2015-01-01

Cold rooms are commonly used for food storage and preparation, and are usually kept around 40°F following food safety guidelines. Some food preparation employees may spend 8 or more hours inside cold rooms. These employees may not be aware of the risks associated with mildly cold temperatures, dampness, and limited ventilation. We performed an evaluation of cold rooms at an airline catering facility because of concerns with exposure to cold temperatures. We spoke with and observed employees in two cold rooms, reviewed daily temperature logs, evaluated employee’s physical activity, work/rest schedule, and protective clothing. We measured temperature, percent relative humidity, and air velocities at different work stations inside the cold rooms. We concluded that thermal comfort concerns perceived by cold room employees may have been the result of air drafts at their workstations, insufficient use of personal protective equipment due to dexterity concerns, work practices, and lack of knowledge about good health and safety practices in cold rooms. These moderately cold work conditions with low air velocities are not well covered in current occupational health and safety guidelines, and wind chill calculations do not apply. We provide practical recommendations to improve thermal comfort of cold room employees. Engineering control recommendations include the redesigning of air deflectors and installing of suspended baffles. Administrative controls include the changing out of wet clothing, providing hand warmers outside of cold rooms, and educating employees on cold stress. We also recommended providing more options on personal protective equipment. However, there is a need for guidelines and educational materials tailored to employees in moderately cold environments to improve thermal comfort and minimize health and safety problems. PMID:25961447

Fracture Sustainability Pressure, Temperature, Differential Pressure, and Aperture Closure Data

DOE Data Explorer

Tim Kneafsey

2016-09-30

In these data sets, the experiment time, actual date and time, room temperature, sample temperature, upstream and downstream pressures (measured independently), corrected differential pressure (measured independently and corrected for offset and room temperature) indication of aperture closure by linear variable differential transformer are presented. An indication of the sample is in the file name and in the first line of data.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pawar, C. S., E-mail: charudutta-p@yahoo.com; Gujar, M. P.; Mathe, V. L.

Nano crystalline Nickel Zinc ferrite (Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4}) thin films were synthesized by Sol Gel method for gas response. The phase and microstructure of the obtained Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4} thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM). The nanostructured Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4} thin film shows single spinel phase. Magnetic study was obtained with the help of VSM. The effects of working temperature on the gas response were studied. The results reveal that the Ni{sub 0.25}Zn{sub 0.75}Fe{sub 2}O{sub 4} thin film gas sensor shows good selectivity to chlorine gas at roommore » temperature. The sensor shows highest sensitivity (∼50%) at room temperature, indicating its application in detecting chlorine gas at room temperature in the future.« less

Optical and application study of gas-liquid discharge excited by bipolar nanosecond pulse in atmospheric air.

PubMed

Wang, Sen; Wang, Wen-chun; Yang, De-zheng; Liu, Zhi-jie; Zhang, Shuai

2014-10-15

In this study, a bipolar nanosecond pulse with 20ns rising time is employed to generate air gas-liquid diffuse discharge plasma with room gas temperature in quartz tube at atmospheric pressure. The image of the discharge and optical emission spectra of active species in the plasma are recorded. The plasma gas temperature is determined to be approximately 390K by compared the experimental spectra with the simulated spectra, which is slightly higher than the room temperature. The result indicated that the gas temperature rises gradually with pulse peak voltage increasing, while decreases slightly with the electrode gap distance increasing. As an important application, bipolar nanosecond pulse discharge is used to sterilize the common microorganisms (Actinomycetes, Candida albicans and Escherichia coli) existing in drinking water, which performs high sterilization efficiency. Copyright © 2014 Elsevier B.V. All rights reserved.

Evolution of Ge nanoislands on Si(110)-'16 × 2' surface under thermal annealing studied using STM

NASA Astrophysics Data System (ADS)

Gangopadhyay, Subhashis; Yoshimura, Masamichi; Ueda, Kazuyuki

2009-11-01

The initial nucleation of Ge nanoclusters on Si(110) at room temperature (RT), annealing-induced surface roughening and the evolution of three-dimensional Ge nanoislands have been investigated using scanning tunneling microscopy (STM). A few monolayers (ML) of Ge deposited at room temperature lead to the formation of Ge clusters which are homogeneously distributed across the surface. The stripe-like patterns, characteristic of the Si(110)-'16 × 2' surface reconstruction are also retained. Increasing annealing temperatures, however, lead to significant surface diffusion and thus, disruption of the underlying '16 × 2' reconstruction. The annealing-induced removal of the stripe structures (originated from '16 × 2' reconstruction) starts at approximately 300 °C, whereas the terrace structures of Si(110) are thermally stable up to 500 °C. At approximately 650 °C, shallow Ge islands of pyramidal shape with (15,17,1) side facets start to form. Annealing at even higher temperatures enhances Ge island formation. Our findings are explained in terms of partial dewetting of the metastable Ge wetting layer (WL) (formed at room temperature) as well as partial relaxation of lattice strain through three-dimensional (3D) island growth.

Room-temperature storage of medications labeled for refrigeration.

PubMed

Cohen, Victor; Jellinek, Samantha P; Teperikidis, Leftherios; Berkovits, Elliot; Goldman, William M

2007-08-15

Data regarding the recommended maximum duration that refrigerated medications available in hospital pharmacies may be stored safely at room temperature were collected and compiled in a tabular format. During May and June of 2006, the prescribing information for medications labeled for refrigeration as obtained from the supplier were reviewed for data addressing room-temperature storage. Telephone surveys of the products' manufacturers were conducted when this information was not available in the prescribing information. Medications were included in the review if they were labeled to be stored at 2-8 degrees C and purchased by the pharmacy department for uses indicated on the hospital formulary. Frozen antibiotics thawed in the refrigerator and extemporaneously compounded medications were excluded. Information was compiled and arranged in tabular format. The U.S. Pharmacopeia's definition of room temperature (20-25 degrees C [68-77 degrees F]) was used for this review. Of the 189 medications listed in AHFS Drug Information 2006 for storage in a refrigerator, 89 were present in the pharmacy department's refrigerator. Since six manufacturers were unable to provide information for 10 medications, only 79 medications were included in the review. This table may help to avoid unnecessary drug loss and expenditures due to improper storage temperatures. Information regarding the room-temperature storage of 79 medications labeled for refrigerated storage was compiled.

Three-dimensional thermal analysis of a high-level waste repository

DOE Office of Scientific and Technical Information (OSTI.GOV)

Altenbach, T.J.

1979-04-01

The analysis used the TRUMP computer code to evaluate the thermal fields for six repository scenarios that studied the effects of room ventilation, room backfill, and repository thermal diffusivity. The results for selected nodes are presented as plots showing the effect of temperature as a function of time. 15 figures, 6 tables.

Observations on the relationship of structure to the mechanical properties of thin TD-NiCr sheet

NASA Technical Reports Server (NTRS)

Whittenberger, J. D.

1976-01-01

A study of the relationship between structure and mechanical properties of thin TD-NiCr sheet indicated that the elevated temperature tensile, stress-rupture, and creep strength properties are dependent on grain aspect ratio and sheet thickness. In general, the strength properties increase with increasing grain aspect ratio and sheet thickness. Tensile testing revealed an absence of ductility at elevated temperatures (not less than 1144 K). Significant creep damage as determined by subsequent tensile testing at room temperature occurs after very small amounts (less than 0.1%) of prior creep deformation over the temperature range 1144-1477 K. A threshold stress for creep appears to exist. Creep exposure below the threshold stress at T not less than 1366 K results in almost full retention of room temperature tensile properties.

Mobile Neel skyrmions at room temperature: Status and future

DOE PAGES

Jiang, Wanjun; Zhang, Wei; Yu, Guoqiang; ...

2016-03-07

Magnetic skyrmions are topologically protected spin textures that exhibit many fascinating features. As compared to the well-studied cryogenic Bloch skyrmions in bulk materials, we focus on the room- temperature Néel skyrmions in thin-film systems with an interfacial broken inversion symmetry in this article. Specifically, we show the stabilization, the creation, and the implementation of Néel skyrmions that are enabled by the electrical current-induced spin-orbit torques. As a result, towards the nanoscale Néel skyrmions, we further discuss the challenges from both material optimization and imaging characterization perspectives.

Cu/Nitroxyl Catalyzed Aerobic Oxidation of Primary Amines into Nitriles at Room Temperature

PubMed Central

Kim, Jinho; Stahl, Shannon S.

2013-01-01

An efficient catalytic method has been developed for aerobic oxidation of primary amines to the corresponding nitriles. The reactions proceed at room temperature and employ a catalyst consisting of (4,4′-tBu2bpy)CuI/ABNO (ABNO = 9-azabicyclo[3.3.1]nonan-3-one N-oxyl). The reactions exhibit excellent functional group compatibility and substrate scope, and are effective with benzylic, allylic and aliphatic amines. Preliminary mechanistic studies suggest that aerobic oxidation of the Cu catalyst is the turnover-limiting step of the reaction. PMID:24015373

Optical characterization of semiconductor materials by using FTIR-PAS

NASA Astrophysics Data System (ADS)

Arévalo, Fabiola; Saavedra, Renato; Paulraj, M.

2008-11-01

In this paper we discuss the procedures for photoacoustic measurements for semiconducting materials, including bulk samples like Gallium Antimonide (GaSb). The optical absorption at photon energies near the band gap was measured at room temperature using Fourier Transform Infrared Photoacoustic spectroscopy (FTIR-PAS). Measurements were performed using a NEXUS 670 FTIR-spectrometer (from Thermo Nicolet) with a MTEC model 300 PA cell (MTEC Photoacoustics, Inc.). Optical properties of the studied samples were determined from their room temperature PA spectra and band gaps were calculated directly from absorption spectra

Cu/Nitroxyl Catalyzed Aerobic Oxidation of Primary Amines into Nitriles at Room Temperature.

PubMed

Kim, Jinho; Stahl, Shannon S

2013-07-05

An efficient catalytic method has been developed for aerobic oxidation of primary amines to the corresponding nitriles. The reactions proceed at room temperature and employ a catalyst consisting of (4,4'- t Bu 2 bpy)CuI/ABNO (ABNO = 9-azabicyclo[3.3.1]nonan-3-one N -oxyl). The reactions exhibit excellent functional group compatibility and substrate scope, and are effective with benzylic, allylic and aliphatic amines. Preliminary mechanistic studies suggest that aerobic oxidation of the Cu catalyst is the turnover-limiting step of the reaction.

An acoustic on-chip goniometer for room temperature macromolecular crystallography.

PubMed

Burton, C G; Axford, D; Edwards, A M J; Gildea, R J; Morris, R H; Newton, M I; Orville, A M; Prince, M; Topham, P D; Docker, P T

2017-12-05

This paper describes the design, development and successful use of an on-chip goniometer for room-temperature macromolecular crystallography via acoustically induced rotations. We present for the first time a low cost, rate-tunable, acoustic actuator for gradual in-fluid sample reorientation about varying axes and its utilisation for protein structure determination on a synchrotron beamline. The device enables the efficient collection of diffraction data via a rotation method from a sample within a surface confined droplet. This method facilitates efficient macromolecular structural data acquisition in fluid environments for dynamical studies.

Giant volume magnetostriction in the Y{sub 2}Fe{sub 17} single crystal at room temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nikitin, S. A., E-mail: nikitin@phys.msu.ru; Pankratov, N. Yu.; Smarzhevskaya, A. I.

2015-05-21

An investigation of the Y{sub 2}Fe{sub 17} compound belonging to the class of intermetallic alloys of rare-earth and 3d-transition metals is presented. The magnetization, magnetostriction, and thermal expansion of the Y{sub 2}Fe{sub 17} single crystal were studied. The forced magnetostriction and magnetostriction constants were investigated in the temperature range of the magnetic ordering close to the room temperature. The giant field induced volume magnetostriction was discovered in the room temperature region in the magnetic field up to 1.2 T. The contributions of both anisotropic single-ion and isotropic pair exchange interactions to the volume magnetostriction and magnetostriction constants were determined. The experimentalmore » results were interpreted within the framework of the Standard Theory of Magnetostriction and the Landau thermodynamic theory. It was found out that the giant values of the volume magnetostriction were caused by the strong dependence of the 3d-electron Coulomb charge repulsion on the deformations and width of the 3d-electron energy band.« less

Near-infrared localized surface plasmon resonance of self-growing W-doped VO2 nanoparticles at room temperature

NASA Astrophysics Data System (ADS)

Nishikawa, Kazutaka; Kishida, Yoshihiro; Ito, Kota; Tamura, Shin-ichi; Takeda, Yasuhiko

2017-11-01

Nanoparticles (NPs) of vanadium dioxide (VO2) in the metal state exhibit localized surface plasmon resonance (LSPR) at 1200-1600 nm, which fills the gap between the absorption ranges of silicon and the LSPR of conventional transparent conductor NPs (ZnO:Al, In2O3:Sn, etc.). However, two issues of the lithographic process for NP formation and the metal-insulator transition temperature (69 °C) higher than room temperature have made it difficult to use VO2 NPs for applications such as energy conversion devices, near infrared (NIR) light detectors, and bio-therapy. In this study, we developed a self-growing process for tungsten (W)-doped VO2 NPs that are in the metal state at room temperature, using sputter deposition and post-lamp annealing. The changes in the LSPR peak wavelengths with the NP size were well controlled by changing the deposited film thickness and oxygen pressure during the post-annealing treatment. The presented results resolve the difficulties of using the metal-insulator transition material VO2 for practical NIR utilization.

Anisotropy influence on the failure of Ti6Al4V sheets deformed at room and elevated temperature

NASA Astrophysics Data System (ADS)

Wang, Q. L.; Ghiotti, A.; Bruschi, S.

2018-05-01

Ti6Al4V sheets are usually difficult-to-form at room temperature as a consequence of their strong basal texture and hcp crystal lattice. The heating of the alloy below the beta transus temperature is recognized to enhance its formability, reducing the flow stress and increasing the ductility. However, the influence of the sheet anisotropy on the material failure hasn't been studied yet. To this aim, the paper presents the anisotropy influence on the failure characteristics of Ti6Al4V titanium alloy sheets making use of tensile tests carried out at room temperature and 600°C on smooth, notched and shear samples in order to have various stress states. The fracture strain is measured and the effect of the sample orientation and stress state is identified. To determine the actual stress state for each sample geometry, a numerical model is set up and calibrated using elasto-plastic data from uni-axial tensile tests on smooth samples. Finally, the fracture surfaces are observed through SEM analysis to explain the failure characteristics.

Effects of air annealing on CdS quantum dots thin film grown at room temperature by CBD technique intended for photosensor applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaikh, Shaheed U.; Desale, Dipalee J.; Siddiqui, Farha Y.

2012-11-15

Graphical abstract: The effect of different intensities (40, 60 100 and 200 W) of light on CdS quantum dots thin film annealed at 350 °C indicating enhancement in (a) photo-current and (b) photosensitivity. Highlights: ► The preparation of CdS nanodot thin film at room temperature by M-CBD technique. ► Study of air annealing on prepared CdS nanodots thin film. ► The optimized annealing temperature for CdS nanodot thin film is 350 °C. ► Modified CdS thin films can be used in photosensor application. -- Abstract: CdS quantum dots thin-films have been deposited onto the glass substrate at room temperature usingmore » modified chemical bath deposition technique. The prepared thin films were further annealed in air atmosphere at 150, 250 and 350 °C for 1 h and subsequently characterized by scanning electron microscopy, ultraviolet–visible spectroscopy, electrical resistivity and I–V system. The modifications observed in morphology and opto-electrical properties of the thin films are presented.« less

Extremely elevated room-temperature kinetic isotope effects quantify the critical role of barrier width in enzymatic C-H activation.

PubMed

Hu, Shenshen; Sharma, Sudhir C; Scouras, Alexander D; Soudackov, Alexander V; Carr, Cody A Marcus; Hammes-Schiffer, Sharon; Alber, Tom; Klinman, Judith P

2014-06-11

The enzyme soybean lipoxygenase (SLO) has served as a prototype for hydrogen-tunneling reactions, as a result of its unusual kinetic isotope effects (KIEs) and their temperature dependencies. Using a synergy of kinetic, structural, and theoretical studies, we show how the interplay between donor-acceptor distance and active-site flexibility leads to catalytic behavior previously predicted by quantum tunneling theory. Modification of the size of two hydrophobic residues by site-specific mutagenesis in SLO reduces the reaction rate 10(4)-fold and is accompanied by an enormous and unprecedented room-temperature KIE. Fitting of the kinetic data to a non-adiabatic model implicates an expansion of the active site that cannot be compensated by donor-acceptor distance sampling. A 1.7 Å resolution X-ray structure of the double mutant further indicates an unaltered backbone conformation, almost identical side-chain conformations, and a significantly enlarged active-site cavity. These findings show the compelling property of room-temperature hydrogen tunneling within a biological context and demonstrate the very high sensitivity of such tunneling to barrier width.

Red-emission phosphor's brightness deterioration by x-ray and brightness recovery phenomenon by heating.

PubMed

Nakamura, Masaaki; Chida, Koichi; Inaba, Yohei; Kobayashi, Ryota; Zuguchi, Masayuki

2017-06-26

There are no feasible real-time and direct skin dosimeters for interventional radiology. One would be available if there were x-ray phosphors that had no brightness change caused by x-ray irradiation, but the emission of the Y 2 O 3 :Eu, (Y, Gd, Eu)BO 3 , and YVO 4 :Eu phosphors investigated in our previous study was reduced by x-ray irradiation. We found that the brightness of those phosphors recovered, and the purpose of this study is to investigate their recovery phenomena. It is expected that more kinds of phosphors could be used in x-ray dosimeters if the brightness changes caused by x-rays are elucidated and prevented. Three kinds of phosphors-Y 2 O 3 :Eu, (Y, Gd, Eu)BO 3 , and YVO 4 :Eu-were irradiated by x-rays (2 Gy) to reduce their brightness. After the irradiation, brightness changes occurring at room temperature and at 80 °C were investigated. The irradiation reduced the brightness of all the phosphors by 5%-10%, but the brightness of each recovered immediately both at room temperature and at 80 °C. The recovery at 80 °C was faster than that at room temperature, and at both temperatures the recovered brightness remained at 95%-98% of the brightness before the x-ray irradiation. The brightness recovery phenomena of Y 2 O 3 :Eu, (Y, Gd, Eu)BO 3 , and YVO 4 :Eu phosphors occurring after brightness deterioration due to x-ray irradiation were found to be more significant at 80 °C than at room temperature. More kinds of phosphors could be used in x-ray scintillation dosimeters if the reasons for the brightness changes caused by x-rays were elucidated.

Nonlinear Vibrational Spectroscopy: a Method to Study Vibrational Self-Trapping

NASA Astrophysics Data System (ADS)

Hamm, Peter; Edler, Julian

We review the capability of nonlinear vibrational spectroscopy to study vibrational self-trapping in hydrogen-bonded molecular crystals. For that purpose, the two relevant coupling mechanisms, excitonic coupling and nonlinear exciton-phonon coupling, are first introduced separately using appropriately chosen molecular systems as examples. Both coupling mechanisms are subsequently combined, yielding vibrational selftrapping. The experiments unambiguously prove that both the N-H and the C=O band of crystalline acetanilide (ACN), a model system for proteins, show vibrational self-trapping. The C=O band is self-trapped only at low enough temperature, while thermally induced disorder destroys the mechanism at room temperature. The binding energy of the N-H band, on the other hand, is considerably larger and self-trapping survives thermal fluctuations even at room temperature.

High-Temperature Dielectric Properties of Aluminum Nitride Ceramic for Wireless Passive Sensing Applications

PubMed Central

Liu, Jun; Yuan, Yukun; Ren, Zhong; Tan, Qiulin; Xiong, Jijun

2015-01-01

The accurate characterization of the temperature-dependent permittivity of aluminum nitride (AlN) ceramic is quite critical to the application of wireless passive sensors for harsh environments. Since the change of the temperature-dependent permittivity will vary the ceramic-based capacitance, which can be converted into the change of the resonant frequency, an LC resonator, based on AlN ceramic, is prepared by the thick film technology. The dielectric properties of AlN ceramic are measured by the wireless coupling method, and discussed within the temperature range of 12 °C (room temperature) to 600 °C. The results show that the extracted relative permittivity of ceramic at room temperature is 2.3% higher than the nominal value of 9, and increases from 9.21 to 10.79, and the quality factor Q is decreased from 29.77 at room temperature to 3.61 at 600 °C within the temperature range. PMID:26370999

Self-locking threaded fasteners

DOEpatents

Glovan, R.J.; Tierney, J.C.; McLean, L.L.; Johnson, L.L.

1996-01-16

A threaded fastener with a shape memory alloy (SMA) coatings on its threads is disclosed. The fastener has special usefulness in high temperature applications where high reliability is important. The SMA coated fastener is threaded into or onto a mating threaded part at room temperature to produce a fastened object. The SMA coating is distorted during the assembly. At elevated temperatures the coating tries to recover its original shape and thereby exerts locking forces on the threads. When the fastened object is returned to room temperature the locking forces dissipate. Consequently the threaded fasteners can be readily disassembled at room temperature but remains securely fastened at high temperatures. A spray technique is disclosed as a particularly useful method of coating of threads of a fastener with a shape memory alloy. 13 figs.

Room temperature, air crystallized perovskite film for high performance solar cells

DOE PAGES

Dubey, Ashish; Kantack, Nicholas; Adhikari, Nirmal; ...

2016-05-31

For the first time, room temperature heating free growth and crystallization of perovskite films in ambient air without the use of thermal annealing is reported. Highly efficient perovskite nanorod-based solar cells were made using ITO/PEDOT:PSS/CH 3NH 3PbI 3 nanorods/PC 60BM/rhodamine/Ag. All the layers except PEDOT:PSS were processed at room temperature thereby eliminating the need for thermal treatment. Perovskite films were spin coated inside a N-2 filled glovebox and immediately were taken outside in air having 40% relative humidity (RH). Exposure to humid air was observed to promote the crystallization process in perovskite films even at room temperature. Perovskite films keptmore » for 5 hours in ambient air showed nanorod-like morphology having high crystallinity, with devices exhibiting the highest PCE of 16.83%, which is much higher than the PCE of 11.94% for traditional thermally annealed perovskite film based devices. Finally, it was concluded that moisture plays an important role in room temperature crystallization of pure perovskite nanorods, showing improved optical and charge transport properties, which resulted in high performance solar cells.« less

Non-local electrical spin injection and detection in germanium at room temperature

NASA Astrophysics Data System (ADS)

Rortais, F.; Vergnaud, C.; Marty, A.; Vila, L.; Attané, J.-P.; Widiez, J.; Zucchetti, C.; Bottegoni, F.; Jaffrès, H.; George, J.-M.; Jamet, M.

2017-10-01

Non-local carrier injection/detection schemes lie at the very foundation of information manipulation in integrated systems. This paradigm consists in controlling with an external signal the channel where charge carriers flow between a "source" and a well separated "drain." The next generation electronics may operate on the spin of carriers in addition to their charge and germanium appears as the best hosting material to develop such a platform for its compatibility with mainstream silicon technology and the predicted long electron spin lifetime at room temperature. In this letter, we demonstrate injection of pure spin currents (i.e., with no associated transport of electric charges) in germanium, combined with non-local spin detection at 10 K and room temperature. For this purpose, we used a lateral spin valve with epitaxially grown magnetic tunnel junctions as spin injector and spin detector. The non-local magnetoresistance signal is clearly visible and reaches ≈15 mΩ at room temperature. The electron spin lifetime and diffusion length are 500 ps and 1 μm, respectively, the spin injection efficiency being as high as 27%. This result paves the way for the realization of full germanium spintronic devices at room temperature.

High-resolution ionization detector and array of such detectors

DOEpatents

McGregor, Douglas S [Ypsilanti, MI; Rojeski, Ronald A [Pleasanton, CA

2001-01-16

A high-resolution ionization detector and an array of such detectors are described which utilize a reference pattern of conductive or semiconductive material to form interaction, pervious and measurement regions in an ionization substrate of, for example, CdZnTe material. The ionization detector is a room temperature semiconductor radiation detector. Various geometries of such a detector and an array of such detectors produce room temperature operated gamma ray spectrometers with relatively high resolution. For example, a 1 cm.sup.3 detector is capable of measuring .sup.137 Cs 662 keV gamma rays with room temperature energy resolution approaching 2% at FWHM. Two major types of such detectors include a parallel strip semiconductor Frisch grid detector and the geometrically weighted trapezoid prism semiconductor Frisch grid detector. The geometrically weighted detector records room temperature (24.degree. C.) energy resolutions of 2.68% FWHM for .sup.137 Cs 662 keV gamma rays and 2.45% FWHM for .sup.60 Co 1.332 MeV gamma rays. The detectors perform well without any electronic pulse rejection, correction or compensation techniques. The devices operate at room temperature with simple commercially available NIM bin electronics and do not require special preamplifiers or cooling stages for good spectroscopic results.

Microstructure development during equal channel angular drawing of Al at room temperature

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakkingal, U.; Suriadi, A.B.; Thomson, P.F.

1998-08-11

In this study 3004 aluminum alloy can-stock remelt (composition 99.9% Al) was subjected to Equal Channel Angular Drawing (ECAD) at room temperature. Tests were conducted to an applied true strain of 2.95. Mechanical properties like tensile strength, ductility at fracture, and microhardness were measured. The development of the substructure was studied using optical and transmission electron microscopy. Subgrain sizes and their angular misorientations were measured as a function of the applied strain. In general, a substructure that consists of cells and subgrains was seen to evolve, as is expected for the case of high SFE fcc metals.

Preliminary metallographic studies of ball fatigue under rolling-contact conditions

NASA Technical Reports Server (NTRS)

Bear, H Robert; Butler, Robert H

1957-01-01

The metallurgical results produced on balls tested in the rolling-contact fatigue spin rig were studied by metallographic examination. Origin and progression of fatigue failures were observed. These evaluations were made on SAE 52100 and AISI M-1 balls fatigue tested at room temperature (80 F) and 200 to 250 F. Most failures originated subsurface in shear; inclusions, structure changes, and directionalism adversely affected ball fatigue life. Structures in the maximum-shear-stress region of the balls of both materials were stable at room temperature and unstable at 200 to 250 F. Failures were of the same type as those found in full-scale bearings.

First-Principles Study of Native Defects in TlBr: Carrier Trapping, Compensation, and Polarization Phemomenon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Mao-Hua

2010-01-01

First-principles calculations are carried out to study the native defect properties in TlBr. Three important results emerge: (1) the native defects are benign in terms of electron trapping because the low-energy defects do not induce electron traps; (2) the dominant defects in nearly stoichiometric TlBr are Schottky defects that pin the Fermi level near the midgap, leading to high resistivity; and (3) the calculated low diffusion barriers for several native defects show that ionic conductivity can occur at room temperature. The important impacts of these material properties on the room-temperature radiation detection using TlBr are discussed.

First-principles study of native defects in TlBr: Carrier trapping, compensation, and polarization phemomenon

NASA Astrophysics Data System (ADS)

Du, Mao-Hua

2010-09-01

First-principles calculations are carried out to study the native defect properties in TlBr. Three important results emerge: (1) the native defects are benign in terms of electron trapping because the low-energy defects do not induce electron traps; (2) the dominant defects in nearly stoichiometric TlBr are Schottky defects that pin the Fermi level near the midgap, leading to high resistivity; and (3) the calculated low diffusion barriers for several native defects show that ionic conductivity can occur at room temperature. The important impacts of these material properties on the room-temperature radiation detection using TlBr are discussed.

Serial femtosecond X-ray diffraction of enveloped virus microcrystals

DOE PAGES

Lawrence, Robert M.; Conrad, Chelsie E.; Zatsepin, Nadia A.; ...

2015-08-20

Serial femtosecond crystallography (SFX) using X-ray free-electron lasers has produced high-resolution, room temperature, time-resolved protein structures. We report preliminary SFX of Sindbis virus, an enveloped icosahedral RNA virus with ~700 Å diameter. Microcrystals delivered in viscous agarose medium diffracted to ~40 Å resolution. Small-angle diffuse X-ray scattering overlaid Bragg peaks and analysis suggests this results from molecular transforms of individual particles. Viral proteins undergo structural changes during entry and infection, which could, in principle, be studied with SFX. This is a pertinent step toward determining room temperature structures from virus microcrystals that may enable time-resolved studies of enveloped viruses.

Room temperature synthesis of biodiesel using sulfonated graphitic carbon nitride

PubMed Central

Baig, R. B. Nasir; Verma, Sanny; Nadagouda, Mallikarjuna N.; Varma, Rajender S.

2016-01-01

Sulfonation of graphitic carbon nitride (g-CN) affords a polar and strongly acidic catalyst, Sg-CN, which displays unprecedented reactivity and selectivity in biodiesel synthesis and esterification reactions at room temperature. PMID:27991593

An Evaluation of High Temperature Airframe Seals for Advanced Hypersonic Vehicles

NASA Technical Reports Server (NTRS)

DeMange, Jeffrey J.; Dunlap, Patrick H.; Steinetz, Bruce M.; Drlik, Gary J.

2007-01-01

High temperature seals are required for advanced hypersonic airframe applications. In this study, both spring tube thermal barriers and innovative wafer seal systems were evaluated under relevant hypersonic test conditions (temperatures, pressures, etc.) via high temperature compression testing and room temperature flow assessments. Thermal barriers composed of a Rene 41 spring tube filled with Saffil insulation and overbraided with a Nextel 312 sheath showed acceptable performance at 1500 F in both short term and longer term compression testing. Nextel 440 thermal barriers with Rene 41 spring tubes and Saffil insulation demonstrated good compression performance up to 1750 F. A silicon nitride wafer seal/compression spring system displayed excellent load performance at temperatures as high as 2200 F and exhibited room temperature leakage values that were only 1/3 those for the spring tube rope seals. For all seal candidates evaluated, no significant degradation in leakage resistance was noted after high temperature compression testing. In addition to these tests, a superalloy seal suitable for dynamic seal applications was optimized through finite element techniques.

Highly responsive ground state of PbTaSe 2 : Structural phase transition and evolution of superconductivity under pressure

DOE PAGES

Kaluarachchi, Udhara S.; Deng, Yuhang; Besser, Matthew F.; ...

2017-06-09

Transport and magnetic studies of PbTaSe 2 under pressure suggest the existence of two superconducting phases with the low temperature phase boundary at ~ 0.25 GPa that is defined by a very sharp, first order, phase transition. The first order phase transition line can be followed via pressure dependent resistivity measurements, and is found to be near 0.12 GPa near room temperature. Transmission electron microscopy and x-ray diffraction at elevated temperatures confirm that this first order phase transition is structural and occurs at ambient pressure near ~ 425 K. The new, high temperature/high pressure phase has a similar crystal structuremore » and slightly lower unit cell volume relative to the ambient pressure, room temperature structure. Based on first-principles calculations this structure is suggested to be obtained by shifting the Pb atoms from the 1 a to 1 e Wyckoff position without changing the positions of Ta and Se atoms. PbTaSe 2 has an exceptionally pressure sensitive, structural phase transition with Δ T s / Δ P ≈ -1400 K/GPa near room temperature, and ≈ -1700 K/GPa near 4 K. This first order transition causes a ~ 1 K (~ 25 % ) steplike decrease in T c as pressure is increased through 0.25 GPa.« less

Analysis of temperature difference on the total of energy expenditure during static bicycle exercise

NASA Astrophysics Data System (ADS)

Sugiono

2016-04-01

How to manage energy expenditure for cyclist is very crucial part to achieve a good performance. As the tropical situation, the differences of temperature level might be contributed in energy expenditure and durability. The aim of the paper is to estimate and to analysis the configuration of energy expenditure for static cycling activity based on heart rate value in room with air conditioning (AC)/no AC treatment. The research is started with study literatures of climate factors, temperature impact on human body, and definition of energy expenditure. The next step is design the experiment for 5 participants in 2 difference models for 26.80C - 74% relative humidity (room no AC) and 23,80C - 54.8% relative humidity (room with AC). The participants’ heart rate and blood pressure are measured in rest condition and in cycling condition to know the impact of difference temperature in energy expenditure profile. According to the experiment results, the reducing of the temperature has significantly impact on the decreasing of energy expenditure at average 0.3 Kcal/minute for all 5 performers. Finally, the research shows that climate condition (temperature and relative humidity) are very important factors to manage and to reach a higher performance of cycling sport.

Comparison studies of rheological and thermal behaviors of ionic liquids and nanoparticle ionic liquids.

PubMed

Xu, Yiting; Zheng, Qiang; Song, Yihu

2015-08-14

Novel nanoparticle ionic liquids (NILs) are prepared by grafting modified nanoparticles with long-chain ionic liquids (ILs). The NIL behaves like a liquid at ambient temperature. We studied the rheological behavior of the IL and NIL over the range of 10-55 °C and found an extraordinary difference between the IL and NIL: a small content of nanosilica (7%) moderately improves the crystallinity by 7% of the poly(ethylene glycol) (PEG) segment in the IL, and it improves the dynamic moduli significantly (by 5 times at room temperature). It retards the decay temperature (by 10 °C) of the dynamic moduli during heating as well. The thermal rheological hysteresis observed during heating-cooling temperature sweeps is ascribed to the melting-recrystallization of the PEG segments. Meanwhile, the IL and NIL express accelerated crystallization behavior in comparison with the oligomeric anion. For the first time, we find that ILs and NILs are able to form nanoparticle-containing spherulites at room temperature after long time aging.

A study on tensile deformation at room temperature and 650 °C in the directional solidified Ni-base superalloy GTD-111

NASA Astrophysics Data System (ADS)

Pauzi, AA; Ghaffar, MH Abdul; Chang, SY; Ng, GP; Husin, S.

2017-10-01

GTD-111 DS generally used for gas turbine blades is a high performance Ni-base superalloy. This alloy, with high volume of γ’ phase, has excellent tensile properties at high temperature. The effect of temperature on the tensile deformation of GTD-111 DS was investigated by using tensile test and microstructure evaluation of the fractured specimens. The tensile behaviour of GTD-111 DS was studied in the room temperature (RT) and 650 °C. From the yield strength results, the yield strength decreases from the average of 702.72 MPa to the average of 645.62 MPa with the increase of temperature from RT to 650 °C. The scanning electron microscope (SEM) results on fractured specimens confirmed that the tensile behaviour affected by deformation of the surface at 650 °C compared to fractured surface at RT. Based on the laboratory testing results, the correlation between tensile deformation of fractured surface and yield strength were discussed.

Microstructural effects on the deformation and fracture of the alloy Ti-25Al-10Nb-3B-1Mo. Final report, 1 July 1988-15 December 1992

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ward, C.H.

1992-12-01

The effects of microstructure and temperature on tensile and fracture behavior were explored for the titanium aluminide alloy Ti-25Al-lONb-3V-lMo (atomic percent). Three microstructures were selected for this study in an attempt to determine the role of the individual microstructural constituents. the three microstructures studied were an alpha-2 + beta processed microstructure with a fine Widmanstaetten microstructure, a beta processed microstructure with a fine Widmanstaetten microstructure, and a beta processed microstructure with a coarse Widmanstaetten microstructure. Tensile testing of both round and flat specimens was conducted in vacuum at elevated temperature and in air at room and elevated temperatures. Extensive fractographymore » and specimen sectioning were used to study tensile deformation and the effects of environment on this alloy. Room temperature fracture toughness testing using compact tension specimens was conducted. Elevated temperature toughness testing was performed using J-bend bar specimens in an air environment. Again, extensive fractography and specimen sectioning were used to study the elevated temperature toughening mechanisms of this alloy.... Titanium, Titanium aluminide, Intermetallic, Fracture toughness, Tensile behavior, Fractography environmental interaction.« less

The room-temperature synthesis of anisotropic CdHgTe quantum dot alloys: a "molecular welding" effect.

PubMed

Taniguchi, Shohei; Green, Mark; Lim, Teck

2011-03-16

The room-temperature chemical transformation of spherical CdTe nanoparticles into anisotropic alloyed CdHgTe particles using mercury bromide in a toluene/methanol system at room temperature has been investigated. The resulting materials readily dissolved in toluene and exhibited a significant red-shift in the optical properties toward the infrared region. Structural transformations were observed, with electron microscopy showing that the CdTe nanoparticles were chemically attached ('welded') to other CdTe nanoparticles, creating highly complex anisotropic heterostructures which also incorporated mercury.

Bend strengths of reaction bonded silicon nitride prepared from dry attrition milled silicon powder

NASA Technical Reports Server (NTRS)

Herbell, T. P.; Glasgow, T. K.

1979-01-01

Dry attrition milled silicon powder was compacted, sintered in helium, and reaction bonded in nitrogen-4 volume percent hydrogen. Bend strengths of bars with as-nitrided surfaces averaged as high as 210 MPa at room temperature and 220 MPa at 1400 C. Bars prepared from the milled powder were stronger than those prepared from as-received powder at both room temperature and at 1400 C. Room temperature strength decreased with increased milling time and 1400 C strength increased with increased milling time.

Synthesis and characterization of CoPt nanoparticles prepared by room temperature chemical reduction with PAMAM dendrimer as template.

PubMed

Wan, Haiying; Shi, Shifan; Bai, Litao; Shamsuzzoha, Mohammad; Harrell, J W; Street, Shane C

2010-08-01

We describe an approach to synthesize monodisperse CoPt nanoparticles with dendrimer as template by a simple chemical reduction method in aqueous solution using NaBH4 as reducing agent at room temperature. The as-made CoPt nanoparticles buried in the dendrimer matrix have the chemically disordered fcc structure and can be transformed to the fct phase after annealing at 700 degrees C. This is the first report of dendrimer-mediated room temperature synthesis of monodisperse magnetic nanoparticles in aqueous solution.

INNOVATIVE INSTRUMENTATION AND ANALYSIS OF THE TEMPERATURE MEASUREMENT FOR HIGH TEMPERATURE GASIFICATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seong W. Lee

During this reporting period, the literature survey including the gasifier temperature measurement literature, the ultrasonic application and its background study in cleaning application, and spray coating process are completed. The gasifier simulator (cold model) testing has been successfully conducted. Four factors (blower voltage, ultrasonic application, injection time intervals, particle weight) were considered as significant factors that affect the temperature measurement. The Analysis of Variance (ANOVA) was applied to analyze the test data. The analysis shows that all four factors are significant to the temperature measurements in the gasifier simulator (cold model). The regression analysis for the case with the normalizedmore » room temperature shows that linear model fits the temperature data with 82% accuracy (18% error). The regression analysis for the case without the normalized room temperature shows 72.5% accuracy (27.5% error). The nonlinear regression analysis indicates a better fit than that of the linear regression. The nonlinear regression model's accuracy is 88.7% (11.3% error) for normalized room temperature case, which is better than the linear regression analysis. The hot model thermocouple sleeve design and fabrication are completed. The gasifier simulator (hot model) design and the fabrication are completed. The system tests of the gasifier simulator (hot model) have been conducted and some modifications have been made. Based on the system tests and results analysis, the gasifier simulator (hot model) has met the proposed design requirement and the ready for system test. The ultrasonic cleaning method is under evaluation and will be further studied for the gasifier simulator (hot model) application. The progress of this project has been on schedule.« less

Effect of Storage Time and Temperature on Dimensional Stability of Impressions Made with Zinc Oxide Impression Paste

PubMed Central

Habibzadeh, Sareh; Safaeian, Shima; Behruzibakhsh, Marjan; Kaviyani, Parisa; Kharazifard, Mohamadjavad

2016-01-01

Objectives: This study aimed to assess the effect of storage time and temperature on dimensional stability of impressions made with Cavex Outline zinc oxide impression paste. Materials and Methods: A round stainless steel mold with five grooves (three horizontal and two vertical) was used in this in-vitro experimental study. Cavex Outline impression paste was prepared according to the manufacturer’s instructions and applied to the mold. The mold was placed on a block and stored at 35°C and 100% humidity for setting. The impressions were poured with stone immediately and also after 30, 120, 240 and 420 minutes and 24 hours. The distance between the vertical lines on the casts was measured and compared with that in the immediately poured cast. Results: Storage in a refrigerator and at room temperature for zero to seven hours had no significant effect on dimensional stability of the impressions; however, 24 hours of storage in a refrigerator or at room temperature decreased the dimensional stability of Cavex Outline (P=0.001). Also, a significant association was found between dimensional changes following 24 hours of storage in a refrigerator (4°C) and at room temperature (23°C; P<0.01). Conclusions: The optimal pouring time of Cavex Outline impressions with stone is between zero to seven hours, and 24 hours of storage significantly decreases the dimensional stability. PMID:28392816

Ultrahigh-sensitive sensing platform based on p-type dumbbell-like Co3O4 network

NASA Astrophysics Data System (ADS)

Zhou, Tingting; Zhang, Tong; Zhang, Rui; Lou, Zheng; Deng, Jianan; Wang, Lili

2017-12-01

Development of high performance room temperature sensors remains a grand challenge for high demand of practical application. Metal oxide semiconductors (MOSs) have many advantages over others due to their easy functionalization, high surface area, and low cost. However, they typically need a high work temperature during sensing process. Here, p-type sensing layer is reported, consisting of pore-rich dumbbell-like Co3O4 particles (DP-Co3O4) with intrinsic high catalytic activity. The gas sensor (GS) based DP-Co3O4 catalyst exhibits ultrahigh NH3 sensing activity along with excellent stability over other structure based NH3 GSs in room temperature work environment. In addition, the unique structure of DP-Co3O4 with pore-rich and high catalytic activity endows fast gas diffusion rate and high sensitivity at room temperature. Taken together, the findings in this work highlight the merit of integrating highly active materials in p-type materials, offering a framework to develop high-sensitivity room temperature sensing platforms.

Storage stability and composition changes of three cold-pressed nut oils under refrigeration and room temperature conditions.

PubMed

Rabadán, Adrián; Álvarez-Ortí, Manuel; Pardo, José Emilio; Alvarruiz, Andrés

2018-09-01

Chemical composition and stability parameters of three cold-pressed nut oils (almond, walnut and pistachio) were monitored for up to 16 months of storage at 5 °C, 10 °C, 20 °C and room temperature. Freshly pressed pistachio oil had lower peroxide value than almond oil and higher induction period than almond and walnut oils, indicating a higher stability. The peroxide values increased faster at room temperature than at lower temperatures during the storage time, and the highest increase was for pistachio oil stored at room temperature exposed to daylight. The induction period decreased for all three nut oils during the storage time, regardless of the storage conditions. Pistachio oil remained the most stable oil at the end of the storage time, followed by almond oil. The percentage of polyunsaturated fatty acids decreased slightly throughout the storage. Copyright © 2018 Elsevier Ltd. All rights reserved.

Mechanical properties of amorphous and devitrified Ni-Zr alloy thin films: A cyclic nanoindentation study

NASA Astrophysics Data System (ADS)

Bhattacharya, Debarati; Chatterjee, Arnomitra; Jana, Swapan

2018-04-01

Thin films of Ni-Zr glassy alloy were deposited at room temperature by magnetron co-sputtering. The alloy films were vacuum annealed in steps of 200°C from room temperature up to 800 °C, where devitrification finally occurred. Mechanical properties of the films were measured after each thermal anneal, through (cyclic) nanoindentation technique. The hardness values were observed to steadily increase with annealing temperature, as the alloy films underwent an amorphous to crystalline transformation. Grazing incidence X-ray diffraction measurements were performed on the as-deposited and annealed films both before and after nanoindentation. The resistance to plastic deformation was strongly linked to the (nano)structure of the material.

High Temperature Tensile Properties of Unidirectional Hi-Nicalon/Celsian Composites In Air

NASA Technical Reports Server (NTRS)

Gyekenyesi, John Z.; Bansal, Narottam P.

2000-01-01

High temperature tensile properties of unidirectional BN/SiC-coated Hi-Nicalon SiC fiber reinforced celsian matrix composites have been measured from room temperature to 1200 C (2190 F) in air. Young's modulus, the first matrix cracking stress, and the ultimate strength decreased from room temperature to 1200 C (2190 F). The applicability of various micromechanical models, in predicting room temperature values of various mechanical properties for this CMC, has also been investigated. The simple rule of mixtures produced an accurate estimate of the primary composite modulus. The first matrix cracking stress estimated from ACK theory was in good agreement with the experimental value. The modified fiber bundle failure theory of Evans gave a good estimate of the ultimate strength.

Effect of strain on the Curie temperature and band structure of low-dimensional SbSI

NASA Astrophysics Data System (ADS)

Wang, Yiping; Hu, Yang; Chen, Zhizhong; Guo, Yuwei; Wang, Dong; Wertz, Esther A.; Shi, Jian

2018-04-01

Photoferroelectric materials show great promise for developing alternative photovoltaics and photovoltaic-type non-volatile memories. However, the localized nature of the d orbital and large bandgap of most natural photoferroelectric materials lead to low electron/hole mobility and limit the realization of technologically practical devices. Antimony sulpho-iodide (SbSI) is a photoferroelectric material which is expected to have high electron/hole mobility in the ferroelectric state due to its non-local band dispersion and narrow bandgap. However, SbSI exhibits the paraelectric state close to room temperature. In this report, as a proof of concept, we explore the possibility to stabilize the SbSI ferroelectric phase above room temperature via mechanical strain engineering. We synthesized thin low-dimensional crystals of SbSI by chemical vapor deposition, confirmed its crystal structure with electron diffraction, studied its optical properties via photoluminescence spectroscopy and time-resolved photoluminescence spectroscopy, and probed its phase transition using temperature-dependent steady-state photoluminescence spectroscopy. We found that introducing external mechanical strain to these low-dimensional crystals may lead to an increase in their Curie temperature (by ˜60 K), derived by the strain-modified optical phase transition in SbSI and quantified by Kern formulation and Landau theory. The study suggests that strain engineering could be an effective way to stabilize the ferroelectric phase of SbSI at above room temperature, providing a solution enabling its application for technologically useful photoferroelectric devices.

BURNER RIG TESTING OF A500 C/SiC

DTIC Science & Technology

2018-03-17

test program characterized the durability behavior of A500® C/SiC ceramic matrix composite material at room and elevated temperature . Specimens were...7 Figure 6. Typical Room- Temperature Tensile Stress-Versus-Strain Trace for As-Manufactured A500...Operation ......................................... 18 Figure 17. Example of the Burner Rig Temperature Profiles Used

[Distribution of environmental temperature and relative humidity according to the number of conditioned air changes in laboratory animals rooms].

PubMed

Fujita, S; Obara, T; Tanaka, I; Yamauchi, C

1981-01-01

The relation of the rate of circulating air change to room temperature and relative humidity in animal quarters with a central air-conditioning system during heating and cooling seasons was investigated, with the results as follows: During the period of heating, the ambient temperature generally rose with a fall of relative humidity as the number of conditioned air changes per hour was increased. Vertical differences in temperature and humidity between levels of 0.5 and 1.5 m above the floor also diminished with increasing air change rate. This tendency was more conspicuous in small animals rooms with outer walls facing north and west. With increasing rate of air changes, the room temperature was prone to decline and the relative humidity to rise during the period of cooling. There were less vertical differences in temperature and humidity during this period. The velocity of air circulation within the animal quarters and its variations tended to increase progressively with increasing rate of ventilation, though the changes were modest.

Room temperature CO and H2 sensing with carbon nanoparticles.

PubMed

Kim, Daegyu; Pikhitsa, Peter V; Yang, Hongjoo; Choi, Mansoo

2011-12-02

We report on a shell-shaped carbon nanoparticle (SCNP)-based gas sensor that reversibly detects reducing gas molecules such as CO and H(2) at room temperature both in air and inert atmosphere. Crystalline SCNPs were synthesized by laser-assisted reactions in pure acetylene gas flow, chemically treated to obtain well-dispersed SCNPs and then patterned on a substrate by the ion-induced focusing method. Our chemically functionalized SCNP-based gas sensor works for low concentrations of CO and H(2) at room temperature even without Pd or Pt catalysts commonly used for splitting H(2) molecules into reactive H atoms, while metal oxide gas sensors and bare carbon-nanotube-based gas sensors for sensing CO and H(2) molecules can operate only at elevated temperatures. A pristine SCNP-based gas sensor was also examined to prove the role of functional groups formed on the surface of functionalized SCNPs. A pristine SCNP gas sensor showed no response to reducing gases at room temperature but a significant response at elevated temperature, indicating a different sensing mechanism from a chemically functionalized SCNP sensor.

Improvement of Superplasticity in High-Mg Aluminum Alloys by Sacrifice of Some Room Temperature Formability

NASA Astrophysics Data System (ADS)

Jin, H.; Amirkhiz, B. Shalchi; Lloyd, D. J.

2018-03-01

The mechanical properties of fully annealed Al-4.6 wt pct Mg alloys with different levels of Mn and Fe have been characterized at room and superplastic forming (SPF) temperatures. The effects of Mn and Fe on the intermetallic phase, grain structure, and cavitation were investigated and correlated to the formability at different temperatures. Although both Mn and Fe contribute to the formation of Al6(Mn,Fe) phase, which refines the grain structure by particle-stimulated nucleation and Zener pinning, their effects are different. An increasing Mn reduces the room temperature formability due to the increasing number of intermetallic particles, but significantly improves the superplasticity by fine grain size-induced grain boundary sliding. Meanwhile, the Fe makes the constituent particles very coarse, resulting in reduced formability at all temperatures due to extensive cavitation. A combination of high Mn and low Fe is therefore beneficial to SPF, while low levels of both elements are good for cold forming. Consequently, the superplasticity of high-Mg aluminum alloys can be significantly improved by modifying the chemical composition with sacrifice of some room temperature formability.

Storage of breast milk: effect of temperature and storage duration on microbial growth.

PubMed

Igumbor, E O; Mukura, R D; Makandiramba, B; Chihota, V

2000-09-01

To study the effect of storage duration at varying temperature ranges, the pattern of microbial isolates and the quantity of colony-forming units (CFU) on expressed breast milk. Cross sectional study. Bacteriology laboratory, University of Zimbabwe in Parirenyatwa Hospital, Harare. The temperature, storage duration and types of micro-organisms in freshly expressed breast milk. Freshly expressed human breast milk contained microbial non-pathogens of skin flora. There was no growth of organisms in stored breast milk after four hours, eight hours, 24 hours and 72 hours storage duration at temperature ranges 0 to 4 degrees C (freezing temperature), 4 to 10 degrees C (refrigerator temperature), 15 to 27 degrees C (room temperature) and 30 to 38 degrees C (high temperature) respectively. Growth was detected after the storage durations and organisms isolated were both pathogens and non-pathogens with low counts. Average colony counts was (CFU < 200). The study revealed that storage duration for expressed breast milk should not exceed 24 hours in refrigerator temperature (4 to 10 degrees C), eight hours at room temperature (15 to 27 degrees C) and four hours at high temperature (30 to 38 degrees C). Although freezing temperature (0 to 4 degrees C) seemed safest for breast milk storage, short-term storage in a freezer is not recommended due to likely the hazards of the thawing process.

Study of 57Fe Mössbauer effect in RFe 2Zn 20 ( R = Lu, Yb, Gd)

DOE PAGES

Bud’ko, Sergey L.; Kong, Tai; Ma, Xiaoming; ...

2015-08-04

In this document we report measurements of 57Fe Mössbauer spectra for RFe 2Zn 20 ( R = Lu, Yb, Gd) from ~ 4.5 K to room temperature. The obtained isomer shift values are very similar for all three compounds, their temperature dependence was analyzed within the Debye model and resulted in an estimate of the Debye temperatures of 450-500 K. The values of quadrupole splitting at room temperature change with the cubic lattice constant a in a linear fashion. For GdFe 2Zn 20, ferromagnetic order is seen as an appearance of a sextet in the spectra. The 57Fe site hyperfinemore » field for T → 0 was evaluated to be ~ 2.4 T.« less

Effect of water temperature and air stream velocity on performance of direct evaporative air cooler for thermal comfort

NASA Astrophysics Data System (ADS)

Aziz, Azridjal; Mainil, Rahmat Iman; Mainil, Afdhal Kurniawan; Listiono, Hendra

2017-01-01

The aim of this work was to determine the effects of water temperature and air stream velocity on the performance of direct evaporative air cooler (DEAC) for thermal comfort. DEAC system requires the lower cost than using vapor compression refrigeration system (VCRS), because VCRS use a compressor to circulate refrigerant while DEAC uses a pump for circulating water in the cooling process to achieve thermal comfort. The study was conducted by varying the water temperature (10°C, 20°C, 30°C, 40°C, and 50°C) at different air stream velocity (2,93 m/s, 3.9 m/s and 4,57 m/s). The results show that the relative humidity (RH) in test room tends to increase with the increasing of water temperature, while on the variation of air stream velocity, RH remains constant at the same water temperature, because the amount of water that evaporates increase with the increasing water temperature. The cooling effectiveness (CE) increase with the increasing of air stream velocity where the higher CE was obtained at lower water temperature (10°C) with high air velocity (4,57m/s). The lower room temperature (26°C) was achieved at water temperature 10°C and air stream velocity 4.57 m/s with the relative humidity 85,87%. DEAC can be successfully used in rooms that have smoothly air circulation to fulfill the indoor thermal comfort.

Cardiac peptide stability, aprotinin and room temperature: importance for assessing cardiac function in clinical practice.

PubMed

Buckley, M G; Marcus, N J; Yacoub, M H

1999-12-01

Brain natriuretic peptide (BNP), atrial natriuretic peptide (ANP) and N-terminal ANP are good research indices of the severity of heart failure. The stability of these peptides at room temperature has become an important factor in assessing their use as indicators of cardiac function in routine clinical practice. Inhibitors such as aprotinin are routinely added in the blood collection process, but may provide no benefit in sample collection and routine clinical practice. We assessed the stability of BNP, ANP and N-terminal ANP in blood samples collected in either the presence or the absence of the protease inhibitor aprotinin. Blood, either with or without aprotinin, was processed immediately (initial; 0 h) and after blood samples had been left for 3 h, 2 days or 3 days at room temperature. These times were chosen to reflect processing in a hospital outpatient clinic (2-3 h), or when posted from general practice (2-3 days). Initial plasma BNP, ANP and N-terminal ANP levels in the absence of aprotinin were 28.2+/-5.4, 44.2+/-7.9 and 1997+/-608 pg/ml respectively, and were not significantly different from initial values in the presence of aprotinin (29.0+/-5.9, 45.2+/-8.0 and 2009+/-579 pg/ml respectively). After 3 h at room temperature, there was a significant fall in ANP in the absence of aprotinin (36. 7+/-7.9 pg/ml; P<0.005), but not in the presence of aprotinin (41. 2+/-7.6 pg/ml). Both BNP and N-terminal ANP were unchanged in either the absence (BNP, 27.6+/-5.5 pg/ml; N-terminal ANP, 2099+/-613 pg/ml) or the presence (BNP, 29.4+/-5.6 pg/ml; N-terminal ANP, 1988+/-600 pg/ml) of aprotinin. After 2 days at room temperature, ANP had fallen significantly in both the absence (16.9+/-3.4 pg/ml) and the presence (24.0+/-5.0 pg/ml) of aprotinin compared with initial values, and there was a significant difference in ANP levels in the absence and presence of aprotinin (P<0.001). ANP levels had decreased further after 3 days at room temperature, to 11.9+/-3.4 pg/ml (no aprotinin) and 20.3+/-5.0 pg/ml (aprotinin added); these values were significantly different (P=0.002). In contrast, there was no change in the levels of BNP or N-terminal ANP after 2 or 3 days at room temperature, in either the absence or the presence of aprotinin. These studies indicate that aprotinin adds little benefit to the stability of cardiac peptides at room temperature. Blood samples for BNP and N-terminal ANP measurement used as a test of heart function in hospital clinics and by general practitioners in the community could be taken into blood tubes containing only EDTA as anticoagulant and without the additional step of adding the routinely used inhibitor aprotinin.

Evaluation of microRNA Stability in Plasma and Serum from Healthy Dogs.

PubMed

Enelund, Lars; Nielsen, Lise N; Cirera, Susanna

2017-01-01

Early and specific detection of cancer is of great importance for successful treatment of the disease. New biomarkers, such as microRNAs, could improve treatment efficiency and survival ratio. In human medicine, deregulation of microRNA profiles in circulation has shown great potential as a new type of biomarker for cancer diagnostics. There are, however, few studies of circulating microRNAs in dogs. Extracellular circulating microRNAs have shown a high level of stability in human blood and other body fluids. Nevertheless, there are still important issues to be solved before microRNAs can be applied routinely as a clinical tool, one of them being their stability over time in media commonly used for blood sampling. Evaluation of the stability of microRNA levels in plasma and serum from healthy dogs after storage at room temperature for different time points before being processed. The levels of four microRNAs (cfa-let-7a, cfa-miR-16, cfa-miR-23a and cfa-miR-26a) known to be stably expressed from other canine studies, have been measured by quantitative real-time PCR (qPCR). MicroRNA levels were found sufficiently stable for gene profiling in serum- and plasma stored at room temperature for 1 hour but not for samples stored at room temperature for 24 hours. Storage at room temperature of serum and plasma samples intended for microRNA profiling should be kept for a minimum period of time before proceeding with RNA isolation. For the four microRNAs investigated in the present study, we did not find significant differences in microRNA levels between serum and plasma samples from the same time point. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

IMPROVED SYNTHESIS OF ROOM TEMPERATURE IONIC LIQUIDS

EPA Science Inventory

Room temperature ionic liquids (RTILs), molten salts comprised of N-alkylimidazolium cations and various anions, have received significant attention due to their commercial potential in a variety of chemical applications especially as substitutes for conventional volatile organic...

Nickel-catalyzed synthesis of aryl trifluoromethyl sulfides at room temperature.

PubMed

Zhang, Cheng-Pan; Vicic, David A

2012-01-11

Inexpensive nickel-bipyridine complexes were found to be active for the trifluoromethylthiolation of aryl iodides and aryl bromides at room temperature using the convenient [NMe(4)][SCF(3)] reagent. © 2011 American Chemical Society

Simulation of effects of direction and air flow speed on temperature distribution in the room covered by various roof materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sukanto, H., E-mail: masheher@uns.ac.id; Budiana, E. P., E-mail: budiana.e@gmail.com; Putra, B. H. H., E-mail: benedictus.hendy@gmail.com

The objective of this research is to get a comparison of the distribution of the room temperature by using three materials, namely plastic-rubber composite, clay, and asbestos. The simulation used Ansys Fluent to get the temperature distribution. There were two conditions in this simulations, first the air passing beside the room and second the air passing in front of the room. Each condition will be varied with the air speed of 1 m/s, 2 m/s, 3 m/s, 4 m/s, 5 m/s for each material used. There are three heat transfers in this simulation, namely radiation, convection, and conduction. Based on the ANSI/ ASHRAE Standard 55-2004,more » the results of the simulation showed that the best temperature distribution was the roof of plastic-rubber composites.« less

Electric field modulated ferromagnetism in ZnO films deposited at room temperature

NASA Astrophysics Data System (ADS)

Bu, Jianpei; Liu, Xinran; Hao, Yanming; Zhou, Guangjun; Cheng, Bin; Huang, Wei; Xie, Jihao; Zhang, Heng; Qin, Hongwei; Hu, Jifan

2018-04-01

The ZnO film deposited at room temperature, which is composed of the amorphous-phase background plus a few nanograins or nanoclusters (about 1-2 nm), exhibits room temperature ferromagnetism (FM). Such FM is found to be connected with oxygen vacancies. For the Ta/ZnO/Pt device based on the medium layer ZnO deposited at room temperature, the saturation magnetization not only is modulated between high and low resistive states by electric voltage with DC loop electric current but also increases/decreases through adjusting the magnitudes of positive/negative DC sweeping voltage. Meanwhile, the voltage-controlled conductance quantization is observed in Ta/ZnO/Pt, accompanying the voltage-controlled magnetization. However, the saturation magnetization of the Ta/ZnO/Pt device becomes smaller under positive electric voltage and returns in some extent under negative electric voltage, when the DC loop electric current is not applied.

Room Temperature Memory for Few Photon Polarization Qubits

NASA Astrophysics Data System (ADS)

Kupchak, Connor; Mittiga, Thomas; Jordan, Bertus; Nazami, Mehdi; Nolleke, Christian; Figueroa, Eden

2014-05-01

We have developed a room temperature quantum memory device based on Electromagnetically Induced Transparency capable of reliably storing and retrieving polarization qubits on the few photon level. Our system is realized in a vapor of 87Rb atoms utilizing a Λ-type energy level scheme. We create a dual-rail storage scheme mediated by an intense control field to allow storage and retrieval of any arbitrary polarization state. Upon retrieval, we employ a filtering system to sufficiently remove the strong pump field, and subject retrieved light states to polarization tomography. To date, our system has produced signal-to-noise ratios near unity with a memory fidelity of >80 % using coherent state qubits containing four photons on average. Our results thus demonstrate the feasibility of room temperature systems for the storage of single-photon-level photonic qubits. Such room temperature systems will be attractive for future long distance quantum communication schemes.

Transition from poor ductility to room-temperature superplasticity in a nanostructured aluminum alloy.

PubMed

Edalati, Kaveh; Horita, Zenji; Valiev, Ruslan Z

2018-04-30

Recent developments of nanostructured materials with grain sizes in the nanometer to submicrometer range have provided ground for numerous functional properties and new applications. However, in terms of mechanical properties, bulk nanostructured materials typically show poor ductility despite their high strength, which limits their use for structural applications. The present article shows that the poor ductility of nanostructured alloys can be changed to room-temperature superplastisity by a transition in the deformation mechanism from dislocation activity to grain-boundary sliding. We report the first observation of room-temperature superplasticity (over 400% tensile elongations) in a nanostructured Al alloy by enhanced grain-boundary sliding. The room-temperature grain-boundary sliding and superplasticity was realized by engineering the Zn segregation along the Al/Al boundaries through severe plastic deformation. This work introduces a new boundary-based strategy to improve the mechanical properties of nanostructured materials for structural applications, where high deformability is a requirement.

Protocols for dry DNA storage and shipment at room temperature.

PubMed

Ivanova, Natalia V; Kuzmina, Masha L

2013-09-01

The globalization of DNA barcoding will require core analytical facilities to develop cost-effective, efficient protocols for the shipment and archival storage of DNA extracts and PCR products. We evaluated three dry-state DNA stabilization systems: commercial Biomatrica(®) DNAstable(®) plates, home-made trehalose and polyvinyl alcohol (PVA) plates on 96-well panels of insect DNA stored at 56 °C and at room temperature. Controls included unprotected samples that were stored dry at room temperature and at 56 °C, and diluted samples held at 4 °C and at -20 °C. PCR and selective sequencing were performed over a 4-year interval to test the condition of DNA extracts. Biomatrica(®) provided better protection of DNA at 56 °C and at room temperature than trehalose and PVA, especially for diluted samples. PVA was the second best protectant after Biomatrica(®) at room temperature, whereas trehalose was the second best protectant at 56 °C. In spite of lower PCR success, the DNA stored at -20 °C yielded longer sequence reads and stronger signal, indicating that temperature is a crucial factor for DNA quality which has to be considered especially for long-term storage. Although it is premature to advocate a transition to DNA storage at room temperature, dry storage provides an additional layer of security for frozen samples, protecting them from degradation in the event of freezer failure. All three forms of DNA preservation enable shipment of dry DNA and PCR products between barcoding facilities. © 2013 The Authors. Molecular Ecology Resources published by John Wiley & Sons Ltd.

Comparisons of Damage Evolution between 2D C/SiC and SiC/SiC Ceramic-Matrix Composites under Tension-Tension Cyclic Fatigue Loading at Room and Elevated Temperatures

PubMed Central

Li, Longbiao

2016-01-01

In this paper, comparisons of damage evolution between 2D C/SiC and SiC/SiC ceramic-matrix composites (CMCs) under tension–tension cyclic fatigue loading at room and elevated temperatures have been investigated. Fatigue hysteresis loops models considering multiple matrix cracking modes in 2D CMCs have been developed based on the damage mechanism of fiber sliding relative to the matrix in the interface debonded region. The relationships between the fatigue hysteresis loops, fatigue hysteresis dissipated energy, fatigue peak stress, matrix multiple cracking modes, and interface shear stress have been established. The effects of fiber volume fraction, fatigue peak stress and matrix cracking mode proportion on fatigue hysteresis dissipated energy and interface debonding and sliding have been analyzed. The experimental fatigue hysteresis dissipated energy of 2D C/SiC and SiC/SiC composites at room temperature, 550 °C, 800 °C, and 1100 °C in air, and 1200 °C in vacuum corresponding to different fatigue peak stresses and cycle numbers have been analyzed. The interface shear stress degradation rate has been obtained through comparing the experimental fatigue hysteresis dissipated energy with theoretical values. Fatigue damage evolution in C/SiC and SiC/SiC composites has been compared using damage parameters of fatigue hysteresis dissipated energy and interface shear stress degradation rate. It was found that the interface shear stress degradation rate increases at elevated temperature in air compared with that at room temperature, decreases with increasing loading frequency at room temperature, and increases with increasing fatigue peak stress at room and elevated temperatures. PMID:28773966

Data mining of space heating system performance in affordable housing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Xiaoxin; Yan, Da; Hong, Tianzhen

The space heating in residential buildings accounts for a considerable amount of the primary energy use. Therefore, understanding the operation and performance of space heating systems becomes crucial in improving occupant comfort while reducing energy use. This study investigated the behavior of occupants adjusting their thermostat settings and heating system operations in a 62-unit affordable housing complex in Revere, Massachusetts, USA. The data mining methods, including clustering approach and decision trees, were used to ascertain occupant behavior patterns. Data tabulating ON/OFF space heating states was assessed, to provide a better understanding of the intermittent operation of space heating systems inmore » terms of system cycling frequency and the duration of each operation. The decision tree was used to verify the link between room temperature settings, house and heating system characteristics and the heating energy use. The results suggest that the majority of apartments show fairly constant room temperature profiles with limited variations during a day or between weekday and weekend. Data clustering results revealed six typical patterns of room temperature profiles during the heating season. Space heating systems cycled more frequently than anticipated due to a tight range of room thermostat settings and potentially oversized heating capacities. In conclusion, from this study affirm data mining techniques are an effective method to analyze large datasets and extract hidden patterns to inform design and improve operations.« less

Data mining of space heating system performance in affordable housing

DOE PAGES

Ren, Xiaoxin; Yan, Da; Hong, Tianzhen

2015-02-16

The space heating in residential buildings accounts for a considerable amount of the primary energy use. Therefore, understanding the operation and performance of space heating systems becomes crucial in improving occupant comfort while reducing energy use. This study investigated the behavior of occupants adjusting their thermostat settings and heating system operations in a 62-unit affordable housing complex in Revere, Massachusetts, USA. The data mining methods, including clustering approach and decision trees, were used to ascertain occupant behavior patterns. Data tabulating ON/OFF space heating states was assessed, to provide a better understanding of the intermittent operation of space heating systems inmore » terms of system cycling frequency and the duration of each operation. The decision tree was used to verify the link between room temperature settings, house and heating system characteristics and the heating energy use. The results suggest that the majority of apartments show fairly constant room temperature profiles with limited variations during a day or between weekday and weekend. Data clustering results revealed six typical patterns of room temperature profiles during the heating season. Space heating systems cycled more frequently than anticipated due to a tight range of room thermostat settings and potentially oversized heating capacities. In conclusion, from this study affirm data mining techniques are an effective method to analyze large datasets and extract hidden patterns to inform design and improve operations.« less

Conductivity, dielectric and modulus study of chitosan-methyl cellulose - BMIMTFSI polymer electrolyte doped with cellulose nano crystal

NASA Astrophysics Data System (ADS)

Misenan, Muhammad Syukri Mohamad; Ali, Ernie Suzana; Khiar, Azwani Sofia Ahmad

2018-06-01

In this study, the effect of adding cellulose nanocrystal (CNC) on the conductivity of biopolymer electrolyte (BPE) based on chitosan-methylcellulose-BMIMTFSI has been studied. The samples were prepared via solution casting technique. The film was characterized by impedance spectroscopy HIOKI 3531- 01 LCR Hi-Tester to measure its ionic conductivity at room temperatures over a wide range of frequency between 50Hz-5MHz. Sample with 15 wt% of CNC shows the highest conductivity of 4.82 x 10-6 Scm-1 at room temperature. Dielectric and modulus studies were carried out to further understands the conductivity behavior of the samples. The increase in conductivity is mainly due to the increase in number of charge carriers.

15N NMR study of nitrate ion structure and dynamics in hydrotalcite-like compounds

USGS Publications Warehouse

Hou, X.; James, Kirkpatrick R.; Yu, P.; Moore, D.; Kim, Y.

2000-01-01

We report here the first nuclear magnetic resonance (NMR) spectroscopic study of the dynamical and structural behavior of nitrate on the surface and in the interlayer of hydrotalcite-like compounds (15NO3--HT). Spectroscopically resolvable surface-absorbed and interlayer NO3- have dramatically different dynamical characteristics. The interlayer nitrate shows a well defined, temperature independent uniaxial chemical shift anisotropy (CS A) powder pattern. It is rigidly held or perhaps undergoes rotation about its threefold axis at all temperatures between -100 ??C and +80 ??C and relative humidities (R.H.) from 0 to 100% at room temperature. For surface nitrate, however, the dynamical behavior depends substantially on temperature and relative humidity. Analysis of the temperature and R.H. dependences of the peak width yields reorieritational frequencies which increase from essentially 0 at -100 ??C to 2.6 ?? 105 Hz at 60 ??C and an activation energy of 12.6 kJ/mol. For example, for samples at R.H. = 33%, the surface nitrate is isotropically mobile at frequencies greater than 105 Hz at room temperature, but it becomes rigid or only rotates on its threefold axis at -100 ??C. For dry samples and samples heated at 200 ??C (R.H. near 0%), the surface nitrate is not isotropically averaged at room temperature. In contrast to our previous results for 35Cl--containing hydrotalcite (35Cl--HT), no NMR detectable structural phase transition is observed for 15NO3--HT. The mobility of interlayer nitrate in HT is intermediate between that of carbonate and chloride.

Room temperature magnetism and metal to semiconducting transition in dilute Fe doped Sb1-xSex semiconducting alloy thin films

NASA Astrophysics Data System (ADS)

Agrawal, Naveen; Sarkar, Mitesh; Chawda, Mukesh; Ganesan, V.; Bodas, Dhananjay

2015-02-01

The magnetism was observed in very dilute Fe doped alloy thin film Fe0.008Sb1-xSex, for x = 0.01 to 0.10. These thin films were grown on silicon substrate using thermal evaporation technique. Structural, electrical, optical, charge carrier concentration measurement, surface morphology and magnetic properties were observed using glancing incidence x-ray diffraction (GIXRD), four probe resistivity, photoluminescence, Hall measurement, atomic force microscopy (AFM) and magnetic force microscopy (MFM) techniques, respectively. No peaks of iron were seen in GIXRD. The resistivity results show that activation energy increases with increase in selenium (Se) concentration. The Arrhenius plot reveals metallic behavior below room temperature. The low temperature conduction is explained by variable range-hopping mechanism, which fits very well in the temperature range 150-300 K. The decrease in density of states has been observed with increasing selenium concentration (x = 0.01 to 0.10). There is a metal-to-semiconductor phase transition observed above room temperature. This transition temperature is Se concentration dependent. The particle size distribution ˜47-61 nm is evaluated using AFM images. These thin films exhibit ferromagnetic interactions at room temperature.

Isotropic Elastic Stress Induced Large Temperature Range Liquid Crystal Blue Phase at Room Temperature.

PubMed

Manna, Suman K; Dupont, Laurent; Li, Guoqiang

2016-08-11

A thermodynamically stable blue phase (BP) based on the conventional rod like nematogen is demonstrated for the first time at room temperature by only diluting a chiral-nematic mixture with the help of some nonmesogenic isotropic liquid. It is observed that addition of this isotropic liquid does not only stabilize the BPs at room temperature, but also significantly improves the temperature range (reversible during heating and cooling) of the BPs to the level of more than 28 °C. Apart from that, we have observed its microsecond electro-optic response time and, external electric field induced wavelength tuning, which are the two indispensable requirements for next generation optical devices, photonic displays, lasers, and many more. Here we propose that the isotropic liquid plays two crucial roles simultaneously. On one hand, it reduces the effective elastic moduli (EEM) of the BP mixtures and stabilizes the BPs at room temperature, and on the other hand, it increases the symmetry of the mutual orientation ordering among the neighboring unit cells of the BP. Hence, the resultant mixture becomes better resistive to some microscopic change due to the change in temperature, even over a large range.

Optical detection of electron paramagnetic resonance in room-temperature electron-irradiated ZnO

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vlasenko, L.S.; Watkins, G.D.

The dominant defect observed in the photoluminescence (PL) of room-temperature electron-irradiated ZnO by optical detection of electron paramagnetic resonance (ODEPR) is determined to be the positively charged oxygen vacancy (V{sub O}{sup +}). Its spectrum, labeled L3, was previously observed in a 4.2 K in situ irradiation study [Yu. V. Gorelkinskii and G. D. Watkins, Phys. Rev. B 69, 115212 (2004)], but it was thought there not to be stable at room temperature and was not identified. Here it is found to be stable to 400 deg. C, where it disappears. It is observed as a competing process (negative signal) tomore » the dominant PL band produced by the irradiation at {approx}700 nm, but is positive in a weaker band at {approx}600 nm. Models are presented for its electrical level position in the gap to explain the results. Two other ODEPR signals are also detected, one of which is tentatively identified as also associated with the oxygen vacancy.« less

Influence of testing environment on the room temperature ductility of FeAl alloys

NASA Technical Reports Server (NTRS)

Gaydosh, D. J.; Nathal, M. V.

1990-01-01

The effects of testing atmospheres (air, O2, N2, and vacuum) on the room-temperature ductility of Fe-40Al, Fe-40Al-0.5B, and Fe-50Al alloys were investigated. The results confirmed the decrease in room-temperature ductility of Fe-rich FeAl alloys by the interaction of the aluminide with water vapor, reported previously by Liu et al. (1989). The highest ductilities were measured in the atmosphere with the lowest moisture levels, i.e., in vacuum. It was found that significant ductility is still restricted to Fe-rich alloys (Fe-40Al), as the Fe-50Al alloy remained brittle under all testing conditions. It was also found that slow cooling after annealing was beneficial, and the effect was additive to the environmental effect. The highest ductility measurements in this study were 9 percent elongation in furnace-cooled Fe-40Al and in Fe-40Al-0.5B, when tested in vacuum.

Investigation of room temperature UV emission of ZnO films with different defect densities induced by laser irradiation.

PubMed

Zhao, Yan; Jiang, Yijian

2010-08-01

We studied the room temperature UV emission of ZnO films with different defect densities which is fabricated by KrF laser irradiation process. It is shown room temperature UV photoluminescence of ZnO film is composed of contribution from free-exciton (FX) recombination and its longitudinal-optical phonon replica (FX-LO) (1LO, 2LO). With increase of the defect density, the FX emission decreased and FX-LO emission increased dramatically; and the relative strengths of FX to FX-LO emission intensities determine the peak position and intensity of UV emission. What is more, laser irradiation with moderate energy density could induce the crystalline ZnO film with very flat and smooth surface. This investigation indicates that KrF laser irradiation could effectively modulate the exciton emission and surface morphology, which is important for the application of high performance of UV emitting optoelectronic devices. Copyright 2010 Elsevier B.V. All rights reserved.

Amorphization of nanocrystalline 3C-SiC irradiated with Si+ ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, Weilin; Wang, H.; Zhang, Yanwen

2010-01-01

Irradiation induced amorphization in nanocrystalline and single crystal 3C-SiC has been studied using 1 MeV Si+ ions under identical irradiation conditions at room temperature and 400 K. The disordering behavior has been characterized using in-situ ion channeling and ex-situ x-ray diffraction methods. The results show that, compared to single crystal 3C-SiC, full amorphization of small 3C-SiC grains (~3.8 nm in size) at room temperature occurs at a slightly lower dose. Grain size decreases with increasing dose until a fully amorphized state is attained. The amorphization dose increases at 400 K relative to room temperature. However, at 400 K, the dosemore » for amorphization for 2.0 nm grains is about a factor of 4 and 8 smaller than for 3.0 nm grains and bulk single crystal 3C-SiC, respectively. The behavior is attributed to the dominance of defect-stimulated interfacial amorphization.« less

Cooling a Mechanical Resonator with Nitrogen-Vacancy Centres Using a Room Temperature Excited State Spin-Strain Interaction

DOE PAGES

MacQuarrie, E. R.; Otten, M.; Gray, S. K.; ...

2017-02-06

Cooling a mechanical resonator mode to a sub-thermal state has been a long-standing challenge in physics. This pursuit has recently found traction in the field of optomechanics in which a mechanical mode is coupled to an optical cavity. An alternate method is to couple the resonator to a well-controlled two-level system. Here we propose a protocol to dissipatively cool a room temperature mechanical resonator using a nitrogen-vacancy centre ensemble. The spin ensemble is coupled to the resonator through its orbitally-averaged excited state, which has a spin-strain interaction that has not been previously studied. We experimentally demonstrate that the spin-strain couplingmore » in the excited state is 13.5 ± 0.5 times stronger than the ground state spin-strain coupling. Lastly, we then theoretically show that this interaction, combined with a high-density spin ensemble, enables the cooling of a mechanical resonator from room temperature to a fraction of its thermal phonon occupancy.« less

Room temperature solution processed low dimensional CH3NH3PbI3 NIR detector

NASA Astrophysics Data System (ADS)

Besra, N.; Paul, T.; Sarkar, P. K.; Thakur, S.; Sarkar, S.; Das, A.; Chanda, K.; Sardar, K.; Chattopadhyay, K. K.

2018-05-01

Metal halide perovskites have recently drawn immense research interests among the worldwide scientific community due to their excellent light harvesting capabilities and above all, cost effectiveness. These new class of materials have already been used as efficient optoelectronic devices e.g. solar cells, photo detectors, etc. Here in this work, room temperature NIR (near infra red) response of organic-inorganic lead halide perovskite CH3NH3PbI3 (Methylammonium lead tri iodide) nanorods has been studied. A very simple solution process technique has been adopted to synthesize CH3NH3PbI3 nanostructures at room temperature. The NIR exposure upon the sample resulted in a considerable hike in its dark current with very good responsivity (0.37 mA/W). Along with that, a good on-off ratio (41.8) was also obtained when the sample was treated under a pulsed NIR exposure with operating voltage of 2 V. The specific detectivity of the device came in the order of 1010 Jone.

Highly reliable contacts for lead-salt diode lasers

NASA Astrophysics Data System (ADS)

Lo, W.

1981-02-01

In order to improve the long term reliability of lead-salt diode lasers, ohmic contacts of multilayer, thin-film structures consisting of In plus Au, Pt, Ni, and Pd have been studied. Diode lasers of PbSnTe fabricated with a variety of contacts were tested during room-temperature storage and during accelerated aging tests. The results show that contact reliability can be improved when multiple overlapping films are used. After 4500 h of baking at 60 C, lasers with In-Au-Pd-Au contacts on both sides showed the least resistance increase (10%). For lasers with In-Au-Pt-Au contacts, 1 h of baking at 60 C is equivalent to 2 d storage at room temperature. Extrapolating these results, a 70% increase in contact resistance is expected for this type of laser after 9000 d of storage at room temperature. The data also suggests that a smaller increase in contact resistance can be expected for lasers fabricated with In-Au-Ni and In-Au-Pd-Au contacts.

Cooling a Mechanical Resonator with Nitrogen-Vacancy Centres Using a Room Temperature Excited State Spin-Strain Interaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacQuarrie, E. R.; Otten, M.; Gray, S. K.

Cooling a mechanical resonator mode to a sub-thermal state has been a long-standing challenge in physics. This pursuit has recently found traction in the field of optomechanics in which a mechanical mode is coupled to an optical cavity. An alternate method is to couple the resonator to a well-controlled two-level system. Here we propose a protocol to dissipatively cool a room temperature mechanical resonator using a nitrogen-vacancy centre ensemble. The spin ensemble is coupled to the resonator through its orbitally-averaged excited state, which has a spin-strain interaction that has not been previously studied. We experimentally demonstrate that the spin-strain couplingmore » in the excited state is 13.5 ± 0.5 times stronger than the ground state spin-strain coupling. Lastly, we then theoretically show that this interaction, combined with a high-density spin ensemble, enables the cooling of a mechanical resonator from room temperature to a fraction of its thermal phonon occupancy.« less

Room-Temperature and Aqueous Solution-Processed Two-Dimensional TiS2 as an Electron Transport Layer for Highly Efficient and Stable Planar n-i-p Perovskite Solar Cells.

PubMed

Huang, Peng; Yuan, Ligang; Zhang, Kaicheng; Chen, Qiaoyun; Zhou, Yi; Song, Bo; Li, Yongfang

2018-05-02

In this study, a room-temperature and aqueous solution-processed two-dimensional (2D) transition-metal dichalcogenide TiS 2 was applied as an electron transport layer (ETL) in planar n-i-p perovskite solar cells (Pero-SCs). Upon insertion of the 2D TiS 2 ETL with UV-ozone (UVO) treatment, the power conversion efficiency (PCE) of the planar Pero-SCs was optimized to 18.79%. To the best of our knowledge, this value should be the highest efficiency to date among those PCEs of the n-i-p Pero-SCs with room-temperature-processed metal compound ETLs. More importantly, the n-i-p Pero-SCs with the UVO-treated 2D TiS 2 as an ETL also show extremely high stability, where the average PCE remained over 95% of its initial value after 816 h storage without encapsulation.

An evaluation of the transition temperature range of super-elastic orthodontic NiTi springs using differential scanning calorimetry.

PubMed

Barwart, O; Rollinger, J M; Burger, A

1999-10-01

Differential scanning calorimetry (DSC) was used to determine the transition temperature ranges (TTR) of four types of super-elastic orthodontic nickel-titanium coil springs (Sentalloy). A knowledge of the TTR provides information on the temperature at which a NiTi wire or spring can assume superelastic properties and when this quality disappears. The spring types in this study can be distinguished from each other by their characteristic TTR during cooling and heating. For each tested spring type a characteristic TTR during heating (austenite transformation) and cooling (martensite transformation) was evaluated. The hysteresis of the transition temperature, found between cooling and heating, was 3.4-5.2 K. Depending on the spring type the austenite transformation started (As) at 9.7-17.1 degrees C and finished (Af) at 29.2-37 degrees C. The martensite transformation starting temperature (Ms) was evaluated at 32.6-25.4 degrees C, while Mf (martensite transformation finishing temperature) was 12.7-6.5 degrees C. The results show that the springs become super-elastic when the temperature increases and As is reached. They undergo a loss of super-elastic properties and a rapid decrease in force delivery when they are cooled to Mf. For the tested springs, Mf and As were found to be below room temperature. Thus, at room temperature and some degrees lower, all the tested springs exert super-elastic properties. For orthodontic treatment this means the maintenance of super-elastic behaviour, even when mouth temperature decreases to about room temperature as can occur, for example, during meals.

An XPS study of the stability of Fomblin Z25 on the native oxide of aluminum. [x ray photoelectron spectroscopy

NASA Technical Reports Server (NTRS)

Herrera-Fierro, Pilar; Pepper, Stephen V.; Jones, William R.

1991-01-01

Thin films of Fomblin Z25, a perfluoropolyalkylether lubricant, were vapor deposited onto clean, oxidized aluminum and sapphire surfaces, and their behavior at different temperatures was studied using x ray photoelectron spectroscopy (XPS) and thermal desorption spectroscopy (TDS). It was found that the interfacial fluid molecules decompose on the native oxide at room temperature, and continue to decompose at elevated temperatures, as previous studies had shown to occur on clean metal. TDS indicated that different degradation mechanisms were operative for clean and oxidized aluminum. On sapphire substrates, no reaction was observed at room temperature. Our conclusion is that the native oxide of aluminum is neither passive nor protective towards Fomblin Z25. At high temperatures (150 C) degradation of the polymer on sapphire produced a debris layer at the interface with a chemical composition similar to the one formed on aluminum oxide. Rubbing a Fomblin film on a single crystal sapphire also induced the decomposition of the lubricant in contact with the interface and the formulation of a debris layer.

Advances in processing of NiAl intermetallic alloys and composites for high temperature aerospace applications

NASA Astrophysics Data System (ADS)

Bochenek, Kamil; Basista, Michal

2015-11-01

Over the last few decades intermetallic compounds such as NiAl have been considered as potential high temperature structural materials for aerospace industry. A large number of investigations have been reported describing complex fabrication routes, introducing various reinforcing/alloying elements along with theoretical analyses. These research works were mainly focused on the overcoming of main disadvantage of nickel aluminides that still restricts their application range, i.e. brittleness at room temperature. In this paper we present an overview of research on NiAl processing and indicate methods that are promising in solving the low fracture toughness issue at room temperature. Other material properties relevant for high temperature applications are also addressed. The analysis is primarily done from the perspective of NiAl application in aero engines in temperature regimes from room up to the operating temperature (over 1150 °C) of turbine blades.

Novel room temperature ferromagnetic semiconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Amita

2004-06-01

Today's information world, bits of data are processed by semiconductor chips, and stored in the magnetic disk drives. But tomorrow's information technology may see magnetism (spin) and semiconductivity (charge) combined in one 'spintronic' device that exploits both charge and 'spin' to carry data (the best of two worlds). Spintronic devices such as spin valve transistors, spin light emitting diodes, non-volatile memory, logic devices, optical isolators and ultra-fast optical switches are some of the areas of interest for introducing the ferromagnetic properties at room temperature in a semiconductor to make it multifunctional. The potential advantages of such spintronic devices will bemore » higher speed, greater efficiency, and better stability at a reduced power consumption. This Thesis contains two main topics: In-depth understanding of magnetism in Mn doped ZnO, and our search and identification of at least six new above room temperature ferromagnetic semiconductors. Both complex doped ZnO based new materials, as well as a number of nonoxides like phosphides, and sulfides suitably doped with Mn or Cu are shown to give rise to ferromagnetism above room temperature. Some of the highlights of this work are discovery of room temperature ferromagnetism in: (1) ZnO:Mn (paper in Nature Materials, Oct issue, 2003); (2) ZnO doped with Cu (containing no magnetic elements in it); (3) GaP doped with Cu (again containing no magnetic elements in it); (4) Enhancement of Magnetization by Cu co-doping in ZnO:Mn; (5) CdS doped with Mn, and a few others not reported in this thesis. We discuss in detail the first observation of ferromagnetism above room temperature in the form of powder, bulk pellets, in 2-3 mu-m thick transparent pulsed laser deposited films of the Mn (<4 at. percent) doped ZnO. High-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) spectra recorded from 2 to 200nm areas showed homogeneous distribution of Mn substituting for Zn a 2 + state in the ZnO lattice. Ferromagnetic Resonance (FMR) technique is used to confirm the existence of ferromagnetic ordering at temperatures as high as 425K. The ab initio calculations were found to be consistent with the observation of ferromagnetism arising from fully polarized Mn 2 + state. The key to observed room temperature ferromagnetism in this system is the low temperature processing, which prevents formation of clusters, secondary phases and the host ZnO from becoming n-type. The electronic structure of the same Mn doped ZnO thin films studied using XAS, XES and RIXS, revealed a strong hybridization between Mn 3d and O 2p states, which is an important characteristic of a Dilute magnetic Semiconductor (DMS). It is shown that the various processing conditions like sintering temperature, dopant concentration and the properties of precursors used for making of DMS have a great influence on the final properties. Use of various experimental techniques to verify the physical properties, and to understand the mechanism involved to give rise to ferromagnetism is presented. Methods to improve the magnetic moment in Mn doped ZnO are also described. New promising DMS materials (such as Cu doped ZnO are explored). The demonstrated new capability to fabricate powder, pellets, and thin films of room temperature ferromagnetic semiconductors thus makes possible the realization of a wide range of complex elements for a variety of new multifunctional phenomena related to Spintronic devices as well as magneto-optic components.« less

Room-Temperature-Cured Copolymers for Lithium Battery Gel Electrolytes

NASA Technical Reports Server (NTRS)

Meador, Mary Ann B.; Tigelaar, Dean M.

2009-01-01

Polyimide-PEO copolymers (PEO signifies polyethylene oxide) that have branched rod-coil molecular structures and that can be cured into film form at room temperature have been invented for use as gel electrolytes for lithium-ion electric-power cells. These copolymers offer an alternative to previously patented branched rod-coil polyimides that have been considered for use as polymer electrolytes and that must be cured at a temperature of 200 C. In order to obtain sufficient conductivity for lithium ions in practical applications at and below room temperature, it is necessary to imbibe such a polymer with a suitable carbonate solvent or ionic liquid, but the high-temperature cure makes it impossible to incorporate and retain such a liquid within the polymer molecular framework. By eliminating the high-temperature cure, the present invention makes it possible to incorporate the required liquid.

Temperature dependent GaAs MMIC radiation effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, W.T.; Roussos, J.A.; Gerdes, J.

1993-12-01

The temperature dependence of pulsed neutron and flash x-ray radiation effects was studied in GaAs MMICs. Above room temperature the long term current transients are dominated by electron trapping in previously existing defects. At low temperature in the range 126 to 259 K neutron induced lattice damage appears to play an increasingly important role in producing long term current transients.

Influence of low ambient temperature on epitympanic temperature measurement: a prospective randomized clinical study.

PubMed

Strapazzon, Giacomo; Procter, Emily; Putzer, Gabriel; Avancini, Giovanni; Dal Cappello, Tomas; Überbacher, Norbert; Hofer, Georg; Rainer, Bernhard; Rammlmair, Georg; Brugger, Hermann

2015-11-05

Epitympanic temperature (Tty) measured with thermistor probes correlates with core body temperature (Tcore), but the reliability of measurements at low ambient temperature is unknown. The aim of this study was to determine if commercially-available thermistor-based Tty reflects Tcore in low ambient temperature and if Tty is influenced by insulation of the ear. Thirty-one participants (two females) were exposed to room (23.2 ± 0.4 °C) and low (-18.7 ± 1.0 °C) ambient temperature for 10 min using a randomized cross-over design. Tty was measured using an epitympanic probe (M1024233, GE Healthcare Finland Oy) and oesophageal temperature (Tes) with an oesophageal probe (M1024229, GE Healthcare Finland Oy) inserted into the lower third of the oesophagus. Ten participants wore ear protectors (Arton 2200, Emil Lux GmbH & Co. KG, Wermelskirchen, Switzerland) to insulate the ear from ambient air. During exposure to room temperature, mean Tty increased from 33.4 ± 1.5 to 34.2 ± 0.8 °C without insulation of the ear and from 35.0 ± 0.8 to 35.5 ± 0.7 °C with insulation. During exposure to low ambient temperature, mean Tty decreased from 32.4 ± 1.6 to 28.5 ± 2.0 °C without insulation and from 35.6 ± 0.6 to 35.2 ± 0.9 °C with insulation. The difference between Tty and Tes at low ambient temperature was reduced by 82% (from 7.2 to 1.3 °C) with insulation of the ear. Epitympanic temperature measurements are influenced by ambient temperature and deviate from Tes at room and low ambient temperature. Insulating the ear with ear protectors markedly reduced the difference between Tty and Tes and improved the stability of measurements. The use of models to correct Tty may be possible, but results should be validated in larger studies.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Emre, Baris; Bruno, Nickolaus M.; Yuce Emre, Suheyla

The effect of Nb substitution for Ni in Ni{sub 45}Co{sub 5}Mn{sub 40}Sn{sub 10} magnetic shape memory alloys on their magnetic properties, martensitic transformation characteristics, transformation hysteresis, and magnetocaloric properties was studied using wavelength-dispersive X-ray spectroscopy, differential scanning calorimetry, and the temperature and field dependence of the magnetization. Ni{sub 45}Co{sub 5}Mn{sub 40}Sn{sub 10} alloy has a very low transformation hysteresis; however, the martensitic transformation temperatures are notably above room temperature, which is not desirable for magnetic refrigeration applications. In this study, small quantities of Nb substitution were shown to drastically shift the transformation temperatures to lower temperatures, at a rate ofmore » 68 K/at. % Nb, which is needed for household refrigeration. The austenite Curie temperature also decreased with increasing Nb content. However, a decrease in the latent heat of the martensitic transition was observed, which negatively affects the magnetic field-induced adiabatic temperature change capability. Still, the relatively large transformation entropy and the low transformation hysteresis make the Nb-doped Ni{sub 45}Co{sub 5}Mn{sub 40}Sn{sub 10} alloys potential candidates for solid state refrigeration near room temperature.« less

Zinc coated sheet steel for press hardening

NASA Astrophysics Data System (ADS)

Ghanbari, Zahra N.

Galvanized steels are of interest to enhance corrosion resistance of press-hardened steels, but concerns related to liquid metal embrittlement have been raised. The objective of this study was to assess the soak time and temperature conditions relevant to the hot-stamping process during which Zn penetration did or did not occur in galvanized 22MnB5 press-hardening steel. A GleebleRTM 3500 was used to heat treat samples using hold times and temperatures similar to those used in industrial hot-stamping. Deformation at both elevated temperature and room temperature were conducted to assess the coating and substrate behavior related to forming (at high temperature) and service (at room temperature). The extent of alloying between the coating and substrate was assessed on undeformed samples heat treated under similar conditions to the deformed samples. The coating transitioned from an α + Gamma1 composition to an α (bcc Fe-Zn) phase with increased soak time. This transition likely corresponded to a decrease in availability of Zn-rich liquid in the coating during elevated temperature deformation. Penetration of Zn into the substrate sheet in the undeformed condition was not observed for any of the processing conditions examined. The number and depth of cracks in the coating and substrate steel was also measured in the hot-ductility samples. The number of cracks appeared to increase, while the depth of cracks appeared to decrease, with increasing soak time and increasing soak temperature. The crack depth appeared to be minimized in the sample soaked at the highest soak temperature (900 °C) for intermediate and extended soak times (300 s or 600 s). Zn penetration into the substrate steel was observed in the hot-ductility samples soaked at each hold temperature for the shortest soak time (10 s) before being deformed at elevated temperature. Reduction of area and elongation measurements showed that the coated sample soaked at the highest temperature and longest soak time maintained the highest ductility when compared to the uncoated sample processed under the sample conditions. Fractography of the hot-ductility samples showed features associated with increased ductility with increased soak time for all soak temperatures. Heat treatments (without elevated temperature deformation) and subsequent room temperature deformation were conducted to investigate the "in-service" behavior of 22MnB5. The uncoated and coated specimens deformed at room temperature showed similar ultimate tensile strength and ductility values. The only notable differences in the room temperature mechanical behavior of uncoated and coated samples processed under the same conditions were a result of differences in the substrate microstructure. All samples appeared to have ductile fracture features; features characteristic of liquid metal embrittlement were not observed.

High-capacity NO2 denuder systems operated at various temperatures (298-473 K).

PubMed

Wolf, Jan-Christoph; Niessner, Reinhard

2012-12-01

In this study, we investigated several coatings for high-temperature, high-capacity, and high-efficiency denuder-based NO(2) removal, with the scope to face the harsh conditions and requirements of automotive exhaust gas sampling. As first coating, we propose a potassium iodide (KI)/polyethylene glycol coating with a high removal efficiency (ε > 98%) for about 2 h and 50 ppm NO(2) at room temperature (298 K). At elevated temperatures (423 K), the initial capacity (100 ppmh) is decreased to 15 ppmh. Furthermore, this is the first proposal of the ionic liquid methyl-butyl-imidazolium iodide ([BMIm(+)][I(-)]) as denuder coating material. At room temperature, this ionic liquid exhibits far greater capacity (300 ppmh) and NO(2) removal efficiency (ε > 99.9%) than KI. Nevertheless, KI exhibits a slightly (~10%) higher capacity at elevated temperatures than [BMIm(+)][I(-)]. Both coatings presented are suitable for applications requiring selective denuding of NO(2) at temperatures up to 423 K.

The effects of temperature on the crystalline properties and resistant starch during storage of white bread.

PubMed

Sullivan, William R; Hughes, Jeff G; Cockman, Russell W; Small, Darryl M

2017-08-01

Resistant starch (RS) can form during storage of foods, thereby bestowing a variety of potential health benefits. The purpose of the current study has been to determine the influence of storage temperature and time on the crystallinity and RS content of bread. Loaves of white bread were baked and stored at refrigeration, frozen and room temperatures with analysis over a period of zero to seven days. RS determination and X-ray diffraction (XRD) were used to evaluate the influence of storage temperature and time on total crystallinity and RS content. The rate of starch recrystallisation was affected by storage temperature and time, where refrigeration temperatures accelerated RS formation and total crystallinity more than storage time at both frozen and room temperature. A strong statistical model has been established between RS formation in bread and XRD patterns, having a 96.7% fit indicating the potential of XRD to measure RS concentrations. Copyright © 2017 Elsevier Ltd. All rights reserved.

High pressure–low temperature phase diagram of barium: Simplicity versus complexity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Desgreniers, Serge; Tse, John S., E-mail: John.Tse@usask.ca; State Key Laboratory of Superhard Materials, Jilin University, 130012 Changchun

2015-11-30

Barium holds a distinctive position among all elements studied upon densification. Indeed, it was the first example shown to violate the long-standing notion that high compression of simple metals should preserve or yield close-packed structures. From modest pressure conditions at room temperature, barium transforms at higher pressures from its simple structures to the extraordinarily complex atomic arrangements of the incommensurate and self-hosting Ba-IV phases. By a detailed mapping of the pressure/temperature structures of barium, we demonstrate the existence of another crystalline arrangement of barium, Ba-VI, at low temperature and high pressure. The simple structure of Ba-VI is unlike that ofmore » complex Ba-IV, the phase encountered in a similar pressure range at room temperature. First-principles calculations predict Ba-VI to be stable at high pressure and superconductive. The results illustrate the complexity of the low temperature-high pressure phase diagram of barium and the significant effect of temperature on structural phase transformations.« less

A novel coupled VM-PT cryocooler operating at liquid helium temperature

NASA Astrophysics Data System (ADS)

Pan, Changzhao; Zhang, Tong; Zhou, Yuan; Wang, Junjie

2016-07-01

This paper presents experimental results on a novel two-stage gas-coupled VM-PT cryocooler, which is a one-stage VM cooler coupled a pulse tube cooler. In order to reach temperatures below the critical point of helium-4, a one-stage coaxial pulse tube cryocooler was gas-coupled on the cold end of the former VM cryocooler. The low temperature inertance tube and room temperature gas reservoir were used as phase shifters. The influence of room temperature double-inlet was first investigated, and the results showed that it added excessive heat loss. Then the inertance tube, regenerator and the length of the pulse tube were researched experimentally. Especially, the DC flow, whose function is similar to the double-orifice, was experimentally studied, and shown to contribute about 0.2 K for the no-load temperature. The minimum no-load temperature of 4.4 K was obtained with a pressure ratio near 1.5, working frequency of 2.2 Hz, and average pressure of 1.73 MPa.

Mechanical Behavior of AZ31B Mg Alloy Sheets under Monotonic and Cyclic Loadings at Room and Moderately Elevated Temperatures

PubMed Central

Nguyen, Ngoc-Trung; Seo, Oh Suk; Lee, Chung An; Lee, Myoung-Gyu; Kim, Ji-hoon; Kim, Heon Young

2014-01-01

Large-strain monotonic and cyclic loading tests of AZ31B magnesium alloy sheets were performed with a newly developed testing system, at different temperatures, ranging from room temperature to 250 °C. Behaviors showing significant twinning during initial in-plane compression and untwinning in subsequent tension at and slightly above room temperature were recorded. Strong yielding asymmetry and nonlinear hardening behavior were also revealed. Considerable Bauschinger effects, transient behavior, and variable permanent softening responses were observed near room temperature, but these were reduced and almost disappeared as the temperature increased. Different stress–strain responses were inherent to the activation of twinning at lower temperatures and non-basal slip systems at elevated temperatures. A critical temperature was identified to account for the transition between the twinning-dominant and slip-dominant deformation mechanisms. Accordingly, below the transition point, stress–strain curves of cyclic loading tests exhibited concave-up shapes for compression or compression following tension, and an unusual S-shape for tension following compression. This unusual shape disappeared when the temperature was above the transition point. Shrinkage of the elastic range and variation in Young’s modulus due to plastic strain deformation during stress reversals were also observed. The texture-induced anisotropy of both the elastic and plastic behaviors was characterized experimentally. PMID:28788514

Raman and dielectric studies of GdMnO3 bulk ceramics synthesized from nano powders

NASA Astrophysics Data System (ADS)

Samantaray, S.; Mishra, D. K.; Roul, B. K.

2017-05-01

Nanocrystalline GdMnO3 (GMO) powders has been synthesized by a simple chemical route i. e. pyrophoric reaction technique and then sintered in the form of bulk pellet at 850°C for 24 hours by adopting slow step sintering schedule. It is observed that by reducing the particles size, chemical route enhances the mixing process as well as decreasing the sintering temperature to get single phase material system in compared to the polycrystalline sample prepared directly from the micron sized commercial powder. Raman spectroscopic studies confirm that the sample is in single phase without any detectable impurity. Frequency dependent dielectric properties i.e., dielectric constant (K) and dielectric loss (tanδ) of GMO ceramics sintered at 850°C for 24 hours were studied at room temperature. The sample showed high K value (˜2736) in the frequency of 100 Hz at room temperature.

Room temperature spin valve effect in NiFe/WS2/Co junctions

PubMed Central

Iqbal, Muhammad Zahir; Iqbal, Muhammad Waqas; Siddique, Salma; Khan, Muhammad Farooq; Ramay, Shahid Mahmood

2016-01-01

The two-dimensional (2D) layered electronic materials of transition metal dichalcogenides (TMDCs) have been recently proposed as an emerging canddiate for spintronic applications. Here, we report the exfoliated single layer WS2-intelayer based spin valve effect in NiFe/WS2/Co junction from room temperature to 4.2 K. The ratio of relative magnetoresistance in spin valve effect increases from 0.18% at room temperature to 0.47% at 4.2 K. We observed that the junction resistance decreases monotonically as temperature is lowered. These results revealed that semiconducting WS2 thin film works as a metallic conducting interlayer between NiFe and Co electrodes. PMID:26868638

Room temperature spin valve effect in NiFe/WS₂/Co junctions.

PubMed

Iqbal, Muhammad Zahir; Iqbal, Muhammad Waqas; Siddique, Salma; Khan, Muhammad Farooq; Ramay, Shahid Mahmood

2016-02-12

The two-dimensional (2D) layered electronic materials of transition metal dichalcogenides (TMDCs) have been recently proposed as an emerging canddiate for spintronic applications. Here, we report the exfoliated single layer WS2-intelayer based spin valve effect in NiFe/WS2/Co junction from room temperature to 4.2 K. The ratio of relative magnetoresistance in spin valve effect increases from 0.18% at room temperature to 0.47% at 4.2 K. We observed that the junction resistance decreases monotonically as temperature is lowered. These results revealed that semiconducting WS2 thin film works as a metallic conducting interlayer between NiFe and Co electrodes.

Room temperature, single mode emission from two-section coupled cavity InGaAs/AlGaAs/GaAs quantum cascade laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pierściński, K., E-mail: kamil.pierscinski@ite.waw.pl; Pierścińska, D.; Pluska, M.

2015-10-07

Room temperature, single mode, pulsed emission from two-section coupled cavity InGaAs/AlGaAs/GaAs quantum cascade laser fabricated by focused ion beam processing is demonstrated and analyzed. The single mode emission is centered at 1059.4 cm{sup −1} (9.44 μm). A side mode suppression ratio of 43 dB was achieved. The laser exhibits a peak output power of 15 mW per facet at room temperature. The stable, single mode emission is observed within temperature tuning range, exhibiting shift at rate of 0.59 nm/K.

Temperature-dependent spectroscopic evidences of curcumin in aqueous medium: a mechanistic study of its solubility and stability.

PubMed

Jagannathan, Ramya; Abraham, Priya Mary; Poddar, Pankaj

2012-12-20

In curcumin, keto-enol-enolate equilibrium of the heptadiene-dione moiety determines its physiochemical and antioxidant properties. However, its poor solubility in water at neutral pH and room temperature decreases its bioavailability. Potential therapeutic applications have triggered an interest in manipulating the solubility of curcumin in water as its stability and solubility in water remains poorly understood. Here, the mechanism behind its solubility at various temperatures and the influence of interplay of temperature, intramolecular H-bonding, and intermolecular forces is reported, which leads to aggregation-disaggregation at various temperatures. Remarkable change is observed in temperature-dependent electronic transition behavior of curcumin, however, the absorption spectra after cooling and heating cycles remain unchanged, hinting much better thermal stability of curcumin in water than previously thought. This study indicates that it is perhaps the breaking of intramolecular hydrogen bonding which leads to exposure of polar groups and hence responsible for the dissolution of curcumin at higher temperature. The formation of intermolecular aggregates might be responsible behind a better room temperature stability of the molecules after cooling its aqueous suspension from 90 to 25 °C. These curcumin solubility studies have great application in biological research with reference to bioavailability and to understand target oriented mode of action of curcumin.

Giant room-temperature electrostrictive coefficients in lead-free relaxor ferroelectric ceramics by compositional tuning

NASA Astrophysics Data System (ADS)

Ullah, Aman; Gul, Hafiza Bushra; Ullah, Amir; Sheeraz, Muhammad; Bae, Jong-Seong; Jo, Wook; Ahn, Chang Won; Kim, Ill Won; Kim, Tae Heon

2018-01-01

A thermotropic phase boundary between non-ergodic and ergodic relaxor phases is tuned in lead-free Bi1/2Na1/2TiO3-based ceramics through a structural transition driven by compositional modification (usually named as "morphotropic approach"). The substitution of Bi(Ni1/2Ti1/2)O3 for Bi1/2(Na0.78K0.22)1/2TiO3 induces a transition from tetragonal to "metrically" cubic phase and thereby, the ergodic relaxor ferroelectric phase becomes predominant at room temperature. A shift of the transition temperature (denoted as TF-R) in the non-ergodic-to-ergodic phase transition is corroborated via temperature-dependent dielectric permittivity and loss measurements. By monitoring the chemical composition dependence of polarization-electric field and strain-electric field hysteresis loops, it is possible to track the critical concentration of Bi(Ni1/2Ti1/2)O3 where the (1 - x)Bi0.5(Na0.78K0.22)0.5TiO3-xBi(Ni0.5Ti0.5)O3 ceramic undergoes the phase transition around room temperature. At the Bi(Ni0.5Ti0.5)O3 content of x = 0.050, the highest room-temperature electrostrictive coefficient of 0.030 m4/C2 is achieved with no hysteretic characteristic, which can foster the realization of actual electrostrictive devices with high operational efficiency at room temperature.

Thermal generation of spin current in epitaxial CoFe{sub 2}O{sub 4} thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Er-Jia, E-mail: ejguophysics@gmail.com, E-mail: klaeui@uni-mainz.de; Quantum Condensed Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830; Herklotz, Andreas

2016-01-11

The longitudinal spin Seebeck effect (LSSE) has been investigated in high-quality epitaxial CoFe{sub 2}O{sub 4} (CFO) thin films. The thermally excited spin currents in the CFO films are electrically detected in adjacent Pt layers due to the inverse spin Hall effect. The LSSE signal exhibits a linear increase with increasing temperature gradient, yielding a LSSE coefficient of ∼100 nV/K at room temperature. The temperature dependence of the LSSE is investigated from room temperature down to 30 K, showing a significant reduction at low temperatures, revealing that the total amount of thermally generated magnons decreases. Furthermore, we demonstrate that the spin Seebeck effectmore » is an effective tool to study the magnetic anisotropy induced by epitaxial strain, especially in ultrathin films with low magnetic moments.« less

Performance characteristics of supercapacitor electrodes made of silicon carbide nanowires grown on carbon fabric

NASA Astrophysics Data System (ADS)

Gu, Lin; Wang, Yewu; Fang, Yanjun; Lu, Ren; Sha, Jian

2013-12-01

In this paper, we report the supercapacitor electrodes with excellent cycle stability, which are made of silicon carbide nanowires (SiC NWs) grown on flexible carbon fabric. A high areal capacitance of 23 mF cm-2 is achieved at a scan rate of 50 mV s-1 at room temperature and capacitances increase with the rise of the working temperature. Owing to the excellent thermal stability of SiC NWs and carbon fabric, no observable decrease of capacitance occurs at room temperature (20 °C) after 105 cycles, which satisfies the demands of the commercial applications. Further increasing the measurement temperature to 60 °C, 90% of the initial capacitance is still retained after 105 cycles. This study shows that silicon carbide nanowires on carbon fabric are a promising electrode material for high temperature and stable micro-supercapacitors.

Investigation on the effect of THF on Nitrogen Hydrate formation under isobaric condition

NASA Astrophysics Data System (ADS)

Jamil, N.; Husin, H.; Aman, Z.; Hassan, Z.

2018-03-01

In this paper, we studied nitrogen (N2) hydrate formation in the presence of tetrahydrofuran (THF) under 3 different conditions; different concentration of THF (0, 3 and 30 %(v/v), different temperature setting (room temperature and induced temperature) and different water content (15, 35 and 55 mL) in an isobaric condition. We found that in the presence of THF which acting as an enhancer, hydrate formation kinetic is highly influenced by these parameters. We observed a striking contrast in hydrate formation behaviour observed at room temperature (RT) and induced temperature (IT) with and without the presence of THF under similar operating conditions. At the presence of 30 %(v/v) of THF in 15 mL water, it can be seen that, hydrate tend to form faster than other samples. Visual observation of N2hydrates are also conducted at 30 %(v/v) of THF in 15 mL water.

Room-temperature antiferromagnetic memory resistor.

PubMed

Marti, X; Fina, I; Frontera, C; Liu, Jian; Wadley, P; He, Q; Paull, R J; Clarkson, J D; Kudrnovský, J; Turek, I; Kuneš, J; Yi, D; Chu, J-H; Nelson, C T; You, L; Arenholz, E; Salahuddin, S; Fontcuberta, J; Jungwirth, T; Ramesh, R

2014-04-01

The bistability of ordered spin states in ferromagnets provides the basis for magnetic memory functionality. The latest generation of magnetic random access memories rely on an efficient approach in which magnetic fields are replaced by electrical means for writing and reading the information in ferromagnets. This concept may eventually reduce the sensitivity of ferromagnets to magnetic field perturbations to being a weakness for data retention and the ferromagnetic stray fields to an obstacle for high-density memory integration. Here we report a room-temperature bistable antiferromagnetic (AFM) memory that produces negligible stray fields and is insensitive to strong magnetic fields. We use a resistor made of a FeRh AFM, which orders ferromagnetically roughly 100 K above room temperature, and therefore allows us to set different collective directions for the Fe moments by applied magnetic field. On cooling to room temperature, AFM order sets in with the direction of the AFM moments predetermined by the field and moment direction in the high-temperature ferromagnetic state. For electrical reading, we use an AFM analogue of the anisotropic magnetoresistance. Our microscopic theory modelling confirms that this archetypical spintronic effect, discovered more than 150 years ago in ferromagnets, is also present in AFMs. Our work demonstrates the feasibility of fabricating room-temperature spintronic memories with AFMs, which in turn expands the base of available magnetic materials for devices with properties that cannot be achieved with ferromagnets.

Charge-carrier mobilities in Cd(0.8)Zn(0.2)Te single crystals used as nuclear radiation detectors

NASA Technical Reports Server (NTRS)

Burshtein, Z.; Jayatirtha, H. N.; Burger, A.; Butler, J. F.; Apotovsky, B.; Doty, F. P.

1993-01-01

Charge-carrier mobilities were measured for the first time in Cd(0.8)Zn(0.2)Te single crystals using time-of-flight measurements of charge carriers produced by short (10 ns) light pulses from a frequency-doubled Nd:YAG laser (532 nm). The electron mobility displayed a T exp -1.1 dependence on the absolute temperature T in the range 200-320 K, with a room-temperature mobility of 1350 sq cm/V s. The hole mobility displayed a T exp -2.0 dependence in the same temperature range, with a room-temperature mobility of 120 sq cm/V s. Cd(0.8)Zn(0.2)Te appears to be a very favorable material for a room-temperature electronic nuclear radiation detector.

Heat resistance study of basalt fiber material via mechanical tests

NASA Astrophysics Data System (ADS)

Gao, Y. Q.; Jia, C.; Meng, L.; Li, X. H.

2017-12-01

This paper focuses on the study of the relationship between the fracture strength of basalt rovings and temperature. Strong stretching performance of the rovings has been tested after the treatment at fixed temperatures but different heating time and then the fracture strength of the rovings exposed to the heating at different temperatures and cooled in different modes investigated. Finally, the fracture strength of the basalt material after the heat treatment was studied. The results showed that the room-temperature strength tends to decrease with an increase of the heat treatment time at 250 °C, but it has the local maximum after 2h heating. And the basalt rovings strength increased after the heat treatment up to 200 °C. It was 16.7 percent higher than the original strength. The strength depends not only on the temperature and duration of the heating, but also on the cooling mode. The value of the strength measured after cold water cooling was less by 6.3% compared with an ambient air cooling mode. The room-temperature breaking strength of the rovings heated at 200 °C and 100 °C for 2 hours each increased by about 14.6% with respect to unpretreated basalt rovings.

The Effect of Inorganic Nanoparticles on the Luminescence Properties of the 5CB Liquid Crystal

NASA Astrophysics Data System (ADS)

Bezrodna, T. V.; Klishevich, G. V.; Curmei, N. D.; Melnyk, V. I.; Nesprava, V. V.

2017-09-01

The luminescence spectral characteristics of nanocomposites based on the 5CB liquid crystal with dispersions of inorganic particles of carbon nanotubes (CNTs), the mineral montmorillonite (MMT), and nanotubes of titanium dioxide TiO2 (TNT) were investigated in the temperature range of 4.3-300 K. The IR absorption spectra of the composites at room temperature in the region of 390-4000 cm-1 were studied. The dependence of the luminescent properties of the composites on the physical properties and parameters of the nanoparticles was studied. It was established that the longwave shift of the luminescence spectra of the composites in relation to the spectra of the pure liquid crystal is related to the specific surface area of the nanoparticles. The longwave shifts of the spectra at room and low temperatures are analyzed.

Characterisation of an Al-BN nanocomposite prepared by ball milling and hot extrusion

NASA Astrophysics Data System (ADS)

Arlic, U.; Drozd, Z.; Trojanová, Z.; Molnárová, O.; Kasakewitsch, A.

2017-07-01

Aluminium-matrix-nanocomposites were manufactured by ball milling of microscale aluminium powder with BN nanoparticles in air, followed by subsequent consolidation by hot extrusion. The microstructure of the samples was studied using scanning electron microscopy. Vickers microhardness measurements were used to probe the mechanical properties of the samples. The amplitude dependent damping of the nanocomposites was measured at room temperature after thermal treatment of samples, and the linear thermal expansion was measured over a wide temperature range from room temperature up to 670K in the as-extruded state. The experimental results give a comprehensive picture of the behaviour of this nanocomposite system over the range of thermomechanical treatment conditions examined in this study. Based on these experimental data some possible influences of BN nanoparticles on the anelastic, plastic and thermal properties of microcrystalline aluminium are discussed.

Designing asymmetric multiferroics with strong magnetoelectric coupling

NASA Astrophysics Data System (ADS)

Lu, Xuezeng; Xiang, Hongjun; Rondinelli, James; Materials Theory; Design Group Team

2015-03-01

Multiferroics offer exciting opportunities for electric-field control of magnetism. Single-phase multiferroics suitable for such applications at room temperature need much more study. Here, we propose the concept of an alternative type of multiferroics, namely, the ``asymmetric multiferroic.'' In asymmetric multiferroics, two locally stable ferroelectric states are not symmetrically equivalent, leading to different magnetic properties between these two states. Furthermore, we predict from first principles that a Fe-Cr-Mo superlattice with the LiNbO3-type structure is such an asymmetric multiferroic. The strong ferrimagnetism, high ferroelectric polarization, and significant dependence of the magnetic transition temperature on polarization make this asymmetric multiferroic an ideal candidate for realizing electric-field control of magnetism at room temperature. Our study suggests that the asymmetric multiferroic may provide an alternative playground for voltage control of magnetism and find its applications in spintronics and quantum computing.

Designing asymmetric multiferroics with strong magnetoelectric coupling

NASA Astrophysics Data System (ADS)

Lu, X. Z.; Xiang, H. J.

2014-09-01

Multiferroics offer exciting opportunities for electric-field control of magnetism. Single-phase multiferroics suitable for such applications at room temperature need much more study. Here, we propose the concept of an alternative type of multiferroics, namely, the "asymmetric multiferroic." In asymmetric multiferroics, two locally stable ferroelectric states are not symmetrically equivalent, leading to different magnetic properties between these two states. Furthermore, we predict from first principles that a Fe-Cr-Mo superlattice with the LiNbO3-type structure is such an asymmetric multiferroic. The strong ferrimagnetism, high ferroelectric polarization, and significant dependence of the magnetic transition temperature on polarization make this asymmetric multiferroic an ideal candidate for realizing electric-field control of magnetism at room temperature. Our study suggests that the asymmetric multiferroic may provide an alternative playground for voltage control of magnetism and find its applications in spintronics and quantum computing.

Influence of time, temperature and coagulation on the measurement of C3, C3 split products and C4.

PubMed

Sinosich, M J; Teisner, B; Brandslund, I; Fisher, M; Grudzinskas, J G

1982-11-26

Quantitative and qualitative immunoelectrophoretic analyses of circulating C3, C3 split products and C4 were performed in matched EDTA plasma and serum obtained from 5 normal subjects and stored for up to 48 h at room temperature (18 degrees C-22 degrees C) and 4 degrees C. Fluctuations in apparent levels of C3 were greater in serum than plasma stored at room temperature, a fall in levels seen by 24 h being followed by a significant increase. By contrast, levels of C3 did not alter if stored at 4 degrees C. C4 levels in both EDTA plasma and serum remained unchanged for 24 h, a slight decrease being seen at 48 h. Levels of C4 remained constant if samples were stored at 4 degrees C. Crossed immunoelectrophoresis revealed a significant progressive decrease in C3 levels and a simultaneous increase in C3c occurring after 4 h in serum and 8 h in EDTA plasma, stored at room temperature. In studies conducted at 4 degrees C, similar but delayed fluctuations were seen. A progressive and significant increase in C3d levels was seen in both plasma and serum samples stored at room temperature, levels rising to 276% (plasma) and 308% (serum) of levels seen at zero time. At 4 degrees C marginal increases in C3d levels only were observed. These results suggest that in vitro degradation of C3 and C4 are readily facilitated by temperature, time and coagulation, and that conditions of collection and storage of samples must be optimized for the accurate definition of activation of the complement cascade.

Incubation at room temperature may be an independent factor that induces chlamydospore production in Candida dubliniensis.

PubMed

Sancak, Banu; Colakoglu, Sule; Acikgoz, Ziya Cibali; Arikan, Sevtap

2005-08-01

Production of chlamydospores is one of the phenotypic features used to differentiate Candida albicans and Candida dubliniensis. C. albicans produces few chlamydospores on only cornmeal/rice-Tween agar at room temperature, whereas C. dubliniensis produces abundant chlamydospores at this temperature both on cornmeal agar and some other commonly used media. We tried to determine whether the room temperature is the main factor that induces chlamydospore production of C. dubliniensis, regardless of the medium used. For this purpose, 100 C. albicans and 24 C. dubliniensis isolates were tested for chlamydospore production at room temperature and at 37 degrees C on some routinely used media, including eosin-methylene blue agar (EMB), nutrient agar (NA), nutrient broth (NB), and also on an investigational medium, phenol red agar (PR). At 37 degrees C, none of the isolates produced chlamydospores on any of the tested media. At 26 degrees C, all C. dubliniensis isolates produced abundant chlamydospores and pseudohyphae after 24-48 h on all tested media. At this incubation temperature, all C. albicans isolates failed to produce chlamydospores and pseudohyphae on EMB, NA, and NB, whereas 2 of the C. albicans isolates produced a few chlamydospores on PR. We also observed that all C. dubliniensis isolates tested on EMB and PR produced rough colonies with a hyphal fringe around the colonies, whereas none of the C. albicans isolates showed this property. In conclusion, incubation at 26 degrees C may play the key role for production of abundant chlamydospores and pseudohyphae by C. dubliniensis. Comprehensive molecular studies are needed to clarify the genetic basis of this observation. Using EMB and PR may be an inexpensive, a time-saving, and a simple way of presumptive identification of C. dubliniensis based on chlamydospore formation and colony morphology.

A 2.5-2.7 THz Room Temperature Electronic Source

NASA Technical Reports Server (NTRS)

Maestrini, Alain; Mehdi, Imran; Lin, Robert; Siles, Jose Vicente; Lee, Choonsup; Gill, John; Chattopadhyay, Goutam; Schlecht, Erich; Bertrand, Thomas; Ward, John

2011-01-01

We report on a room temperature 2.5 to 2.7 THz electronic source based on frequency multipliers. The source utilizes a cascade of three frequency multipliers with W-band power amplifiers driving the first stage multiplier. Multiple-chip multipliers are utilized for the two initial stages to improve the power handling capability and a sub-micron anode is utilized for the final stage tripler. Room temperature measurements indicate that the source can put out a peak power of about 14 microwatts with more than 4 microwatts in the 2.5 to 2.7 THz range.

Room temperature ferromagnetism in non-magnetic doped TiO2 nanoparticles

NASA Astrophysics Data System (ADS)

Gómez-Polo, C.; Larumbe, S.; Pastor, J. M.

2013-05-01

Room-temperature ferromagnetism in non-magnetic doped TiO2 semiconductor nanoparticles is analyzed in the present work. Undoped and N-doped TiO2 nanoparticles were obtained employing sol-gel procedure using urea as the nitrogen source. The obtained gels were first dried at 70 °C and afterwards calcined in air at 300 °C. A residual carbon concentration was retained in the samples as a consequence of the organic decomposition process. Post-annealing treatments at 300 °C under air and vacuum conditions were also performed. The crystallographic structure of nanoparticles was analyzed by X-ray diffraction, obtaining a single anatase crystalline phase after the calcinations (mean nanoparticle diameters around 5-8 nm). SQUID magnetometry was employed to analyze the magnetic response of the samples. Whereas for the undoped samples synthesized with hydrolysis rate h = 6, paramagnetic like behavior is observed at room temperature, the N-doped nanoparticles (h = 3) show a weak ferromagnetic response (saturation magnetization ≈10-3 emu/g). Moreover, a clear reinforcement of the room-temperature ferromagnetism response is found with the post-annealing treatments, in particular that performed in vacuum. Thus, the results indicate the dominant role of the oxygen stoichiometry and the oxygen vacancies in the room temperature ferromagnetic response of these TiO2 nanoparticles.

Hydrothermal deformation of granular quartz sand

NASA Astrophysics Data System (ADS)

Karner, Stephen L.; Kronenberg, Andreas K.; Chester, Frederick M.; Chester, Judith S.; Hajash, Andrew

2008-05-01

Isotropic and triaxial compression experiments were performed on porous aggregates of St Peter quartz sand to explore the influence of temperature (to 225°C). During isotropic stressing, samples loaded at elevated temperature exhibit the same sigmoidal stress-strain curves and non-linear acoustic emission rates as have previously been observed from room temperature studies on sands, sandstones, and soils. However, results from our hydrothermal experiments show that the critical effective pressure (P*) associated with the onset of significant pore collapse and pervasive cataclastic flow is lower at increased temperature. Samples subjected to triaxial loading at elevated temperature show yield behavior resembling that observed from room temperature studies on granular rocks and soils. When considered in terms of distortional and mean stresses, the yield strength data for a given temperature define an elliptical envelope consistent with critical state and CAP models from soil mechanics. For the conditions we tested, triaxial yield data at low effective pressure are essentially temperature-insensitive whereas yield levels at high effective pressure are lowered as a function of elevated temperature. We interpret our yield data in a manner consistent with Arrhenius behavior expected for thermally assisted subcritical crack growth. Taken together, our results indicate that increased stresses and temperatures associated with subsurface burial will significantly alter the yield strength of deforming granular media in systematic and predictable ways.

The Effect of Prestrain Temperature on Kinetics of Static Recrystallization, Microstructure Evolution, and Mechanical Properties of Low Carbon Steel

NASA Astrophysics Data System (ADS)

Akbari, Edris; Karimi Taheri, Kourosh; Karimi Taheri, Ali

2018-05-01

In this research, the samples of a low carbon steel sheet were rolled up to a thickness prestrain of 67% at three different temperatures consisted of room, blue brittleness, and subzero temperature. Microhardness, SEM, and tensile tests were carried out to evaluate the static recrystallization kinetics defined by the Avrami equation, microstructural evolution, and mechanical properties. It was found that the Avrami exponent is altered with change in prestrain temperature and it achieves the value of 1 to 1. 5. Moreover, it was indicated that prestraining at subzero temperature followed by annealing at 600 °C leads to considerable enhancement in tensile properties and kinetics of static recrystallization compared to room and blue brittleness temperatures. The prestraining at blue brittleness temperature followed by annealing treatment caused, however, a higher strength and faster kinetics compared with that at room temperature. It was concluded that although from the steel ductility point of view, the blue brittleness temperature is called an unsuitable temperature, but it can be used as prestraining temperature to develop noticeable combination of strength and ductility in low carbon steel.

Wurtzite Spin-Lasers

NASA Astrophysics Data System (ADS)

Xu, Gaofeng; Faria Junior, Paulo E.; Sipahi, Guilherme M.; Zutic, Igor

Lasers in which spin-polarized carriers are injected provide paths to different practical room temperature spintronic devices, not limited to magnetoresistive effects. While theoretical studies of such spin-lasers have focused on zinc-blende semiconductors as their active regions, the first electrically injected carriers at room temperature were recently demonstrated in GaN-based wurtzite semiconductors, recognized also for the key role as highly-efficient light emitting diodes. By focusing on a wurtzite quantum well-based spin-laser, we use accurate electronic structure calculations to develop a microscopic description for its lasing properties. We discuss important differences between wurtzite and zinc-blende spin-lasers.

Conductance bistability of gold nanowires at room temperature

NASA Astrophysics Data System (ADS)

Kiguchi, Manabu; Konishi, Tatsuya; Murakoshi, Kei

2006-03-01

Quantized conductance behavior of gold nanowires was studied under electrochemical potential control. We fabricated 1-nm -long monoatomic wires in solution at room temperature. Electrochemical potential significantly affected the stability of the monoatomic wire and fractional conductance peak occurrence in the conductance histogram. We revealed that the hydrogen adsorption on gold monoatomic wires was a decisive factor of the fractional peak, which was originated from the dynamic structural transition between two bistable states of the monoatomic wire showing the unit and the fractional values of the conductance. We could tune the stability of these bistable states to make the fractional conductance state preferable.

Effect of magnetic field on the electrodeposition of nickel

NASA Astrophysics Data System (ADS)

Subhachandhar, S.; Krishnan, A. Yaadhav; Sivabalan, S.; Narayanan, R.

2012-07-01

This paper investigates the effect of an external magnetic field in the electroplating of Ni, one of the four ferromagnetic materials at the room temperature. Nickel plating is done using Watts bath with a composition of 250g/L of Nickel sulphate, 35g/L of Nickel Chloride, 25g/L of Boric acid with pH between 5 and 6 at room temperature under a current density of 0.05-0.1 A/dm2 under the presence of an external magnetic field to obtain a coherent coating. The arrangement of the coated particles is studied by SEM analysis.

Long-term storage of salivary cortisol samples at room temperature

NASA Technical Reports Server (NTRS)

Chen, Yu-Ming; Cintron, Nitza M.; Whitson, Peggy A.

1992-01-01

Collection of saliva samples for the measurement of cortisol during space flights provides a simple technique for studying changes in adrenal function due microgravity. In the present work, several methods for preserving saliva cortisol at room temperature were investigated using radioimmunoassays for determining cortisol in saliva samples collected on a saliva-collection device called Salivettes. It was found that a pretreatment of Salivettes with citric acid resulted in preserving more than 85 percent of the salivary cortisol for as long as six weeks. The results correlated well with those for a sample stored in a freezer on an untreated Salivette.

Process Studies on Laser Welding of Copper with Brilliant Green and Infrared Lasers

NASA Astrophysics Data System (ADS)

Engler, Sebastian; Ramsayer, Reiner; Poprawe, Reinhart

Copper materials are classified as difficult to weld with state-of-the-art lasers. High thermal conductivity in combination with low absorption at room temperature require high intensities for reaching a deep penetration welding process. The low absorption also causes high sensitivity to variations in surface conditions. Green laser radiation shows a considerable higher absorption at room temperature. This reduces the threshold intensity for deep penetration welding significantly. The influence of the green wavelength on energy coupling during heat conduction welding and deep penetration welding as well as the influence on the weld shape has been investigated.

Room temperature deposition of silicon nanodot clusters by plasma-enhanced chemical vapor deposition.

PubMed

Kim, Jae-Kwan; Kim, Jun Young; Yoon, Jae-Sik; Lee, Ji-Myon

2013-10-01

The formation of nanometer-scale (ns)-Si dots and clusters on p-GaN layers has been studied by controlling the early stage of growth during plasma-enhanced chemical vapor deposition (PECVD) at room temperature. We found that ns-Si dots and clusters formed on the p-GaN surface, indicating that growth was the Volmer-Weber mode. The deposition parameters such as radio frequency (RF) power and processing time mainly influenced the size of the ns-Si dots (40 nm-160 nm) and the density of the ns-Si dot clusters.

Gas Sensitivity Study of Polypyrrole Decorated Graphene Oxide Thick Film

NASA Astrophysics Data System (ADS)

Patil, Pritam; Gaikwad, Ganesh; Patil, Devidas Ramrao; Naik, Jitendra

2016-04-01

Polypyrrole (PPy) and graphene oxide (GO) nanocomposites were prepared by in situ polymerization method. The synthesized nanocomposites were characterized for current-voltage characteristic, Fourier transform infrared spectroscopy, X-ray diffraction and field emission scanning electron microscopy, which gave the evidence of the strong interaction between PPy nanofibers and GO nanosheets. The PPy/GO nanocomposites were used for the sensing of H2S, LPG, CO2 and NH3 gases respectively at room temperature. It was observed that PPy/GO nanocomposites with different GO weight ratios (5, 10 and 20 %) had better selectivity and sensitivity towards NH3 at room temperature.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oda, H., E-mail: h-oda@photon.chitose.ac.jp; Yamanaka, A.; Ozaki, N.

The development of small sized laser operating above room temperature is important in the realization of optical integrated circuits. Recently, micro-lasers consisting of photonic crystals (PhCs) and whispering gallery mode cavities have been demonstrated. Optically pumped laser devices could be easily designed using photonic crystal-slab waveguides (PhC-WGs) with an air-bridge type structure. In this study, we observe lasing at 1.3μm from two-photon pumped InAs-quantum-dots embedded GaAs PhC-WGs above room temperature. This type of compact laser shows promise as a new light source in ultra-compact photonics integrated circuits.

Alternating current conduction studies on polypyrrole-iron nanocomposite at room temperature

NASA Astrophysics Data System (ADS)

Kumar, T. G. Naveen; Megha, R.; Revanasiddappa, M.; Ravikiran, Y. T.; Kumari, S. C. Vijaya

2018-05-01

In the present work, Polypyrrole (PPy) and Polypyrrole-Iron (PPy-Fe) nanocomposite were synthesized separately by chemical polymerisation method and then they were structurally characterised by Fourier transform infrared spectroscopy (FTIR) and Transmission electron microscopy (TEM) techniques. The alternate current (AC) response characteristics at room temperature of PPy and the composite were comparatively studied in the frequency range 100Hz-1MHz. The real part of conductivities of both PPy and the composite were interpreted as power law of frequency and the frequency exponent s was found to lie in the range 0< s<1 in both the cases. The nanocomposite has shown significant improvement in conductivity as compared to PPy.

Effect of high-dose irradiation on quality characteristics of ready-to-eat broiler breast fillets stored at room temperature.

PubMed

Baptista, R F; Teixeira, C E; Lemos, M; Monteiro, M L G; Vital, H C; Mársico, E T; Júnior, C A Conte; Mano, S B

2014-10-01

The effect of high-dose irradiation on the physical, chemical, and bacteriological parameters of ready-to-eat vacuum-packed broiler breast meat after 430 d of storage at room temperature was investigated. Ready-to-eat broiler breast fillets were immersed in brine with garlic powder and then drained, grilled, and vacuum-packed (primary packaging). The high-dose irradiation used was approximately 48 kGy. The treatments were designated as A (irradiated samples stored at room temperature), B (irradiated samples stored at -25°C), and C (nonirradiated samples stored at -25°C). All samples were packaged in polyethylene bags containing aluminum to exclude light (secondary packaging). Proximate composition, pH, 2-thiobarbituric acid reactive substance (TBARS), and heterotrophic aerobic mesophilic bacteria were analyzed during 430 d of storage. Results were analyzed using 1-way ANOVA and the Tukey test. Linear regression was used to analyze the correlation between the results for each parameter and storage time of the different treatments. The gamma radiation caused slight changes (P < 0.05) in the moisture and fat content, regardless of storage temperature. After storage d 110, TBARS values remained stable (P > 0.05) in all the treatments. The preservation methods used were effective in maintaining the mesophilic counts below the detection level during the entire storage period. We concluded that, among the treatments studied, high-dose irradiation with storage at room temperature showed potential for the preservation of ready-to-eat products made from poultry meat, to provide foods safe for consumption. ©2014 Poultry Science Association Inc.

The Impact of Repeated Freeze-Thaw Cycles on the Quality of Biomolecules in Four Different Tissues.

PubMed

Ji, Xiaoli; Wang, Min; Li, Lingling; Chen, Fang; Zhang, Yanyang; Li, Qian; Zhou, Junmei

2017-10-01

High-quality biosamples are valuable resources for biomedical research. However, some tissues are stored without being sectioned into small aliquots and have to undergo repeated freeze-thaw cycles throughout prolonged experimentation. Little is known regarding the effects of repeated freeze-thaw cycles on the quality of biomolecules in tissues. The aim of this study was to evaluate the impact of repeated freeze-thaw (at room temperature or on ice) cycles on biomolecules and gene expression in four different types of tissues. Each fresh tissue was sectioned into seven aliquots and snap-frozen before undergoing repeated freeze-thaw cycles at room temperature or on ice. Biomolecules were extracted and analyzed. Both relative and absolute quantification were used to detect the changes in gene expression. The results indicated that the impact of repeated freeze-thaw cycles on RNA integrity varied by tissue type. Gene expression, including the housekeeping gene, was affected in RNA-degraded samples according to absolute quantification rather than relative quantification. Furthermore, our results suggest that thawing on ice could protect RNA integrity compared with thawing at room temperature. No obvious degradation of protein or DNA was observed with repeated freeze-thaw cycles either at room temperature or on ice. This research provides ample evidence for the necessity of sectioning fresh tissues into small aliquots before snap-freezing, thus avoiding degradation of RNA and alteration of gene expression resulting from repeated freeze-thaw cycles. For frozen tissue samples that were already in storage and had to be used repeatedly during their lifecycle, thawing on ice or sectioned at ultralow temperature is recommended.

Effect of Te inclusions in CdZnTe crystals at different temperatures

NASA Astrophysics Data System (ADS)

Hossain, A.; Bolotnikov, A. E.; Camarda, G. S.; Gul, R.; Kim, K.-H.; Cui, Y.; Yang, G.; Xu, L.; James, R. B.

2011-02-01

CdZnTe crystals often exhibit nonuniformities due to the presence of Te inclusions and dislocations. High concentrations of such defects in these crystals generally entail severe charge-trapping, a major problem in ensuring the device's satisfactory performance. In this study, we employed a high-intensity, high-spatial-resolution synchrotron x-ray beam as the ideal tool to generate charges by focusing it over the large Te inclusions, and then observing the carrier's response at room- and at low-temperatures. A high spatial 5-μm resolution raster scan revealed the fine details of the presence of extended defects, like Te inclusions and dislocations in the CdZnTe crystals. A noticeable change was observed in the efficiency of electron charge collection at low temperature (1 °C), but it was hardly altered at room-temperature.

Room temperature ferromagnetism and luminescent behavior of Ni doped ZnO nanoparticles prepared by coprecipitation method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arora, Deepawali; Mahajan, Aman; Kaur, Parvinder

2016-05-23

The samples of Zn{sub 1-x}Ni{sub x}O (x= 0.00 and 0.05) were prepared using coprecipitation method and annealed at different temperatures. The effect of Ni ion substitution on the structural and optical properties has been studied using X-ray Diffraction, UV-Visible, Photoluminescence and Magnetic measurements. XRD measurements demonstrate that all the prepared samples are wurtzite polycrystalline single phase in nature, ruling out the presence of any secondary phase formation. Ultraviolet visible measurements showed a decrease in band gap with the increase in annealing temperature and doping concentration. The PL data shows the red shift in all the samples and luminescence quenching withmore » Ni doping. Compared to undoped ZnO, Ni doped ZnO showed room temperature ferromagnetism.« less

Controllable deposition of regular lead iodide nanoplatelets and their photoluminescence at room temperature

NASA Astrophysics Data System (ADS)

Kong, Weimin; Li, Guohui; Liang, Qiangbing; Ji, Xingqi; Li, Gang; Ji, Ting; Che, Tao; Hao, Yuying; Cui, Yanxia

2018-03-01

In this work, the synthesis of regular single crystalline lead iodide nanoplatelets are carried out based on the physical vapor phase deposition method. Different lead iodide nanoplatelets are obtained by tuning the location of the mica substrate along with the temperature of the tube furnace. The rules of size, thickness, density of the lead iodide nanoplatelets at varied deposition conditions are analyzed according to the crystal growth principles. It was claimed in literature that the photoluminescence of lead iodide could be obtained only at a low temperature (lower than 200 K). Here, at room temperature, we successfully obtained the photoluminescence spectra of the prepared lead iodide nanoplatelets, which possess two apparent peaks due to the biexcitons and the inelastic scattering of excitons, respectively. Our present study contributes to the development of nanoscaled high performance optoelectronic devices.

Delayed elasticity in Zerodur® at room temperature

NASA Astrophysics Data System (ADS)

Pepi, John W.; Golini, Donald

1991-12-01

Much has been written about structural relaxation, viscous flow, delayed elasticity, hysteresis, and other dimensional stability phenomena of glass and ceramics at elevated temperatures. Less has been documented about similar effects at room temperature. The time dependent phenomenon of delayed elasticity exhibited by Zerodur has been studied at room temperature and is presented here. Using a high-performance mechanical profilometer, a delayed strain on the order of 1 percent is realized over a period of a few weeks, under low stress levels. An independent test using optical interferometry validates the results. A comparison of Corning ULE silica glass is also made. The effect is believed to be related to the alkali oxide content of the glass ceramic and rearrangement of the ion groups within the structure during stress. The effect, apparent under externally applied load, is elastic and repeatable, that is, no hysteresis of permanent set, as measured at elevated temperature, is evidenced within measurement capabilities. Nonetheless, it must be accounted for in determining the magnitude of distortion under load (delayed elastic creep) and upon load removal (delayed elastic recovery). This is particularly important for large lightweight optics which might undergo large strain during fabrication and environmental loading, such as experienced in gravity release or in dynamic control of active optics.

Room Temperature Antiferromagnetic Ordering of Nanocrystalline Tb1.90Ni0.10O3

NASA Astrophysics Data System (ADS)

Mandal, J.; Dalal, M.; Sarkar, B. J.; Chakrabarti, P. K.

2017-02-01

Nanocrystalline Ni-doped terbium oxide (Tb1.90Ni0.10O3) has been synthesized by the co-precipitation method followed by annealing at 700°C for 6 h in vacuum. The crystallographic phase and the substitution of Ni2+ ions in the lattice of Tb2O3 are confirmed by Rietveld analysis of the x-ray diffraction pattern using the software MAUD. High-resolution transmission electron microscopy is also carried out to study the morphology of the sample. Magnetic measurements are carried out at different temperatures from 5 K to 300 K using a superconducting quantum interference device (SQUID) magnetometer. The dependence of the magnetization of Tb1.90Ni0.10O3 as a function of temperature ( M- T) and magnetic field ( M- H) suggests the presence of both paramagnetic and antiferromagnetic phase at room temperature, but antiferromagnetic phase dominates below ˜120 K. The lack of saturation in the M- H curve and good fitting of the M- T curve by the Johnston formula also indicate the presence of both paramagnetic and antiferromagnetic phase at room temperature. Interestingly, an antiferromagnetic to ferromagnetic phase transition is observed below ˜40 K. The result also shows a high value of magnetization at 5 K.

Chemistry of the metal-polymer interfacial region.

PubMed

Leidheiser, H; Deck, P D

1988-09-02

In many polymer-metal systems, chemical bonds are formed that involve metal-oxygen-carbon complexes. Infrared and Mössbauer spectroscopic studies indicate that carboxylate groups play an important role in some systems. The oxygen sources may be the polymer, the oxygen present in the oxide on the metal surface, or atmospheric oxygen. Diffusion of metal ions from the substrate into the polymer interphase may occur in some systems that are cured at elevated temperatures. It is unclear whether a similar, less extensive diffusion occurs over long time periods in systems maintained at room temperature. The interfacial region is dynamic, and chemical changes occur with aging at room temperature. Positron annihilation spectroscopy may have application to characterizing the voids at the metal-polymer interface.

Influence of deformation ageing treatment on microstructure and properties of aluminum alloy 2618

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang Jianhua; Yi Danqing; Su Xuping

2008-07-15

The effects of deformation ageing treatment (DAT) on the microstructure and properties of aluminum alloy 2618 were investigated. The alloy was subjected to deformation ageing treatment which included solution treating at 535 deg. C quenching into water at room-temperature, cold rolling (10%) and further ageing to peak hardness level at 200 deg. C. The electron microscopic studies revealed that the treatment affects the ageing characteristics and the coarsening of ageing phase (S') at elevated-temperature. The dislocation-precipitate tangles substructure couldn't be found in alloy 2618. The tensile and hardness tests showed that deformation-ageing treatment causes a significant improvement in tensile strengthmore » and hardness to alloy 2618 at room- and elevated-temperature.« less

Evaluation of corrective measures implemented for the preventive conservation of fresco paintings in Ariadne’s house (Pompeii, Italy)

PubMed Central

2013-01-01

Background A microclimate monitoring study was conducted in 2008 aimed at assessing the conservation risks affecting the valuable wall paintings decorating Ariadne’s House (Pompeii, Italy). It was found that thermohygrometric conditions were very unfavorable for the conservation of frescoes. As a result, it was decided to implement corrective measures, and the transparent polycarbonate sheets covering three rooms (one of them delimited by four walls and the others composed of three walls) were replaced by opaque roofs. In order to examine the effectiveness of this measure, the same monitoring system comprised by 26 thermohygrometric probes was installed again in summer 2010. Data recorded in 2008 and 2010 were compared. Results Microclimate conditions were also monitored in a control room with the same roof in both years. The average temperature in this room was lower in 2010, and it was decided to consider a time frame of 18 summer days with the same mean temperature in both years. In the rooms with three walls, the statistical analysis revealed that the diurnal maximum temperature decreased about 3.5°C due to the roof change, and the minimum temperature increased 0.5°C. As a result, the daily thermohygrometric variations resulted less pronounced in 2010, with a reduction of approximately 4°C, which is favorable for the preservation of mural paintings. In the room with four walls, the daily fluctuations also decreased about 4°C. Based on the results, other alternative actions are discussed aimed at improving the conservation conditions of wall paintings. Conclusions The roof change has reduced the most unfavorable thermohygrometric conditions affecting the mural paintings, but additional actions should be adopted for a long term preservation of Pompeian frescoes. PMID:23683173

Evaluation of corrective measures implemented for the preventive conservation of fresco paintings in Ariadne's house (Pompeii, Italy).

PubMed

Merello, Paloma; García-Diego, Fernando-Juan; Zarzo, Manuel

2013-05-17

A microclimate monitoring study was conducted in 2008 aimed at assessing the conservation risks affecting the valuable wall paintings decorating Ariadne's House (Pompeii, Italy). It was found that thermohygrometric conditions were very unfavorable for the conservation of frescoes. As a result, it was decided to implement corrective measures, and the transparent polycarbonate sheets covering three rooms (one of them delimited by four walls and the others composed of three walls) were replaced by opaque roofs. In order to examine the effectiveness of this measure, the same monitoring system comprised by 26 thermohygrometric probes was installed again in summer 2010. Data recorded in 2008 and 2010 were compared. Microclimate conditions were also monitored in a control room with the same roof in both years. The average temperature in this room was lower in 2010, and it was decided to consider a time frame of 18 summer days with the same mean temperature in both years. In the rooms with three walls, the statistical analysis revealed that the diurnal maximum temperature decreased about 3.5°C due to the roof change, and the minimum temperature increased 0.5°C. As a result, the daily thermohygrometric variations resulted less pronounced in 2010, with a reduction of approximately 4°C, which is favorable for the preservation of mural paintings. In the room with four walls, the daily fluctuations also decreased about 4°C. Based on the results, other alternative actions are discussed aimed at improving the conservation conditions of wall paintings. The roof change has reduced the most unfavorable thermohygrometric conditions affecting the mural paintings, but additional actions should be adopted for a long term preservation of Pompeian frescoes.

Resetting of circadian melatonin and cortisol rhythms in humans by ordinary room light

NASA Technical Reports Server (NTRS)

Boivin, D. B.; Czeisler, C. A.

1998-01-01

The present study was designed to investigate whether a weak photic stimulus can reset the endogenous circadian rhythms of plasma melatonin and plasma cortisol in human subjects. A stimulus consisting of three cycles of 5 h exposures to ordinary room light (approximately 180 lux), centered 1.5 h after the endogenous temperature nadir, significantly phase-advanced the plasma melatonin rhythm in eight healthy young men compared with the phase delays observed in eight control subjects who underwent the same protocol but were exposed to darkness (p < or = 0.003). After light-induced phase advances, the circadian rhythms of plasma melatonin and plasma cortisol maintained stable temporal relationships with the endogenous core body temperature cycle, consistent with the conclusion that exposure to ordinary indoor room light had shifted a master circadian pacemaker.

Structure of Room Temperature Ionic Liquids on Charged Graphene: An integrated experimental and computational study

NASA Astrophysics Data System (ADS)

Uysal, Ahmet; Zhou, Hua; Lee, Sang Soo; Fenter, Paul; Feng, Guang; Li, Song; Cummings, Peter; Fulvio, Pasquale; Dai, Sheng; McDonough, Jake; Gogotsi, Yury

2014-03-01

Electrical double layer capacitors (EDLCs) with room temperature ionic liquid (RTIL) electrolytes and carbon electrodes are promising candidates for energy storage devices with high power density and long cycle life. We studied the potential and time dependent changes in the electric double layer (EDL) structure of an imidazolium-based room temperature ionic liquid (RTIL) electrolyte at an epitaxial graphene (EG) surface. We used in situ x-ray reflectivity (XR) to determine the EDL structure at static potentials, during cyclic voltammetry (CV) and potential step measurements. The static potential structures were also investigated with fully atomistic molecular dynamics (MD) simulations. Combined XR and MD results show that the EDL structure has alternating anion/cation layers within the first nanometer of the interface. The dynamical response of the EDL to potential steps has a slow component (>10 s) and the RTIL structure shows hysteresis during CV scans. We propose a conceptual model that connects nanoscale interfacial structure to the macroscopic measurements. This material is based upon work supported as part of the Fluid Interface Reactions, Structures and Transport (FIRST) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science (SC), Office of Basic Energy

ROOM TEMPERATURE BULK AND TEMPLATE-FREE SYNTHESIS OF LEUCOEMARLDINE POLYANILINE NANOFIBERS

EPA Science Inventory

Herein, we describe a simple strategy for the bulk and template-free synthesis of reduced leucoemarldine polyaniline nanofibers size ranging from as low as 10 nm to 50 nm without the use of any reducing agents at room temperature.

Heat Capacity of Room-Temperature Ionic Liquids: A Critical Review

NASA Astrophysics Data System (ADS)

Paulechka, Yauheni U.

2010-09-01

Experimental data on heat capacity of room-temperature ionic liquids in the liquid state were compiled and critically evaluated. The compilation contains data for 102 aprotic ionic liquids from 63 literature references and covers the period of time from 1998 through the end of February 2010. Parameters of correlating equations for temperature dependence of the heat capacities were developed.

Fractography handbook of spaceflight metals

NASA Technical Reports Server (NTRS)

Derro, Rebecca J.

1993-01-01

This handbook was produced with the intention of providing failure analysts who work with space flight metals a reference of scanning electron microscope (SEM) fractographs of fracture surfaces produced under known condition. The metals and the fracture conditions were chosen to simulate situations that are encountered in spaceflight applications. This includes tensile overload at both room temperature and liquid nitrogen temperature, and fatigue at room temperature.

In-Plane Shear Testing of Medium and High Modulus Woven Graphite Fiber Reinforced/Polyimide Composites

NASA Technical Reports Server (NTRS)

Gentz, M.; Armentrout, D.; Rupnowski, P.; Kumosa, L.; Shin, E.; Sutter, J. K.; Kumosa, M.

2004-01-01

Iosipescu shear tests were performed at room temperature and at 316 C (600 F) o woven composites with either M40J or M60J graphite fibers and PMR-II-50 polyimide resin matrix. The composites were tested as supplied and after thermo-cycling, with the thermo-cycled composites being tested under dry and wet conditions. Acoustic emission (AE) was monitored during the room and high temperature Iosipescu experiments. The shear stresses at the maximum loads and the shear stresses at the significant onset of AE were determined for the composites as function of temperature and conditioning. The combined effects of thermo-cycling and moisture on the strength and stiffness properties of the composites were evaluated. It was determined that the room and high temperature shear stresses at the maximum loads were unaffected by conditioning. However, at room temperature the significant onset of AE was affected by conditioning; the thermal conditioned wet specimens showed the highest shear stress at the onset of AE followed by thermal-conditioned and then as received specimens. Also, at igh temperature the significant onset of AE occurred in some specimens after the maximum load due to the viscoelastoplastic nature of the matrix material.

A Designed Room Temperature Multilayered Magnetic Semiconductor

NASA Astrophysics Data System (ADS)

Bouma, Dinah Simone; Charilaou, Michalis; Bordel, Catherine; Duchin, Ryan; Barriga, Alexander; Farmer, Adam; Hellman, Frances; Materials Science Division, Lawrence Berkeley National Lab Team

2015-03-01

A room temperature magnetic semiconductor has been designed and fabricated by using an epitaxial antiferromagnet (NiO) grown in the (111) orientation, which gives surface uncompensated magnetism for an odd number of planes, layered with the lightly doped semiconductor Al-doped ZnO (AZO). Magnetization and Hall effect measurements of multilayers of NiO and AZO are presented for varying thickness of each. The magnetic properties vary as a function of the number of Ni planes in each NiO layer; an odd number of Ni planes yields on each NiO layer an uncompensated moment which is RKKY-coupled to the moments on adjacent NiO layers via the carriers in the AZO. This RKKY coupling oscillates with the AZO layer thickness, and it disappears entirely in samples where the AZO is replaced with undoped ZnO. The anomalous Hall effect data indicate that the carriers in the AZO are spin-polarized according to the direction of the applied field at both low temperature and room temperature. NiO/AZO multilayers are therefore a promising candidate for spintronic applications demanding a room-temperature semiconductor.

Super-formable pure magnesium at room temperature.

PubMed

Zeng, Zhuoran; Nie, Jian-Feng; Xu, Shi-Wei; H J Davies, Chris; Birbilis, Nick

2017-10-17

Magnesium, the lightest structural metal, is difficult to form at room temperature due to an insufficient number of deformation modes imposed by its hexagonal structure and a strong texture developed during thermomechanical processes. Although appropriate alloying additions can weaken the texture, formability improvement is limited because alloying additions do not fundamentally alter deformation modes. Here we show that magnesium can become super-formable at room temperature without alloying. Despite possessing a strong texture, magnesium can be cold rolled to a strain at least eight times that possible in conventional processing. The resultant cold-rolled sheet can be further formed without cracking due to grain size reduction to the order of one micron and inter-granular mechanisms becoming dominant, rather than the usual slip and twinning. These findings provide a pathway for developing highly formable products from magnesium and other hexagonal metals that are traditionally difficult to form at room temperature.Replacing steel or aluminium vehicle parts with magnesium would result in reduced emissions, but shaping magnesium without cracking remains challenging. Here, the authors successfully extrude and roll textured magnesium into ductile foil at low temperatures by activating intra-granular mechanisms.

Ultrasensitive Room-Temperature Operable Gas Sensors Using p-Type Na:ZnO Nanoflowers for Diabetes Detection.

PubMed

Jaisutti, Rawat; Lee, Minkyung; Kim, Jaeyoung; Choi, Seungbeom; Ha, Tae-Jun; Kim, Jaekyun; Kim, Hyoungsub; Park, Sung Kyu; Kim, Yong-Hoon

2017-03-15

Ultrasensitive room-temperature operable gas sensors utilizing the photocatalytic activity of Na-doped p-type ZnO (Na:ZnO) nanoflowers (NFs) are demonstrated as a promising candidate for diabetes detection. The flowerlike Na:ZnO nanoparticles possessing ultrathin hierarchical nanosheets were synthesized by a facile solution route at a low processing temperature of 40 °C. It was found that the Na element acting as a p-type dopant was successfully incorporated in the ZnO lattice. On the basis of the synthesized p-type Na:ZnO NFs, room-temperature operable chemiresistive-type gas sensors were realized, activated by ultraviolet (UV) illumination. The Na:ZnO NF gas sensors exhibited high gas response (S of 3.35) and fast response time (∼18 s) and recovery time (∼63 s) to acetone gas (100 ppm, UV intensity of 5 mW cm -2 ), and furthermore, subppm level (0.2 ppm) detection was achieved at room temperature, which enables the diagnosis of various diseases including diabetes from exhaled breath.

Uncertainty in a Markov state model with missing states and rates: Application to a room temperature kinetic model obtained using high temperature molecular dynamics.

PubMed

Chatterjee, Abhijit; Bhattacharya, Swati

2015-09-21

Several studies in the past have generated Markov State Models (MSMs), i.e., kinetic models, of biomolecular systems by post-analyzing long standard molecular dynamics (MD) calculations at the temperature of interest and focusing on the maximally ergodic subset of states. Questions related to goodness of these models, namely, importance of the missing states and kinetic pathways, and the time for which the kinetic model is valid, are generally left unanswered. We show that similar questions arise when we generate a room-temperature MSM (denoted MSM-A) for solvated alanine dipeptide using state-constrained MD calculations at higher temperatures and Arrhenius relation — the main advantage of such a procedure being a speed-up of several thousand times over standard MD-based MSM building procedures. Bounds for rate constants calculated using probability theory from state-constrained MD at room temperature help validate MSM-A. However, bounds for pathways possibly missing in MSM-A show that alternate kinetic models exist that produce the same dynamical behaviour at short time scales as MSM-A but diverge later. Even in the worst case scenario, MSM-A is found to be valid longer than the time required to generate it. Concepts introduced here can be straightforwardly extended to other MSM building techniques.

Low-temperature magnetic properties of greigite (Fe3S4)

NASA Astrophysics Data System (ADS)

Chang, Liao; Roberts, Andrew P.; Rowan, Christopher J.; Tang, Yan; Pruner, Petr; Chen, Qianwang; Horng, Chorng-Shern

2009-01-01

We provide comprehensive low-temperature magnetic results for greigite (Fe3S4) across the spectrum from superparamagnetic (SP) to multidomain (MD) behavior. It is well known that greigite has no low-temperature magnetic transitions, but we also document that it has strong domain-state dependence of magnetic properties at low temperatures. Blocking of SP grains and increasing thermal stability with decreasing temperature is apparent in many magnetic measurements. Thermally stable single-domain greigite undergoes little change in magnetic properties below room temperature. For pseudo-single-domain (PSD)/MD greigite, hysteresis properties and first-order reversal curve diagrams exhibit minor changes at low temperatures, while remanence continuously demagnetizes because of progressive domain wall unpinning. The low-temperature demagnetization is grain size dependent for PSD/MD greigite, with coarser grains undergoing larger remanence loss. AC susceptibility measurements indicate consistent blocking temperatures (TB) for all synthetic and natural greigite samples, which are probably associated with surficial oxidation. Low-temperature magnetic analysis provides much more information about magnetic mineralogy and domain state than room temperature measurements and enables discrimination of individual components within mixed magnetic mineral assemblages. Low-temperature rock magnetometry is therefore a useful tool for studying magnetic mineralogy and granulometry of greigite-bearing sediments.