Synthesis, growth, structural, spectroscopic and optical studies of a new semiorganic nonlinear optical crystal: L-valine hydrochloride.

PubMed

Kirubavathi, K; Selvaraju, K; Valluvan, R; Vijayan, N; Kumararaman, S

2008-04-01

Single crystals of a new semiorganic nonlinear optical (NLO) material, L-valine hydrochloride (LVHCl), having dimensions up to 20 mm x 6 mm x 4 mm have been grown by slow evaporation solution growth technique. Single crystal X-ray diffraction studies confirm that the grown crystal belongs to the monoclinic system. The functional groups presented in the crystal were confirmed by Fourier transform infrared (FTIR) technique. Optical transmission spectrum shows very low absorption in the entire visible region. Differential thermal and thermogravimetric analyses confirmed that the crystal is stable up to 211 degrees C. The powder second harmonic generation (SHG) efficiency of LVHCl is 1.7 times efficient as potassium dihydrogen phosphate (KDP).

Crystal growth and characterization of semi organic nonlinear optical (NLO) piperazinium tetrachlorozincate monohydrate (PTCZ) single crystal

NASA Astrophysics Data System (ADS)

Karuppasamy, P.; Pandian, Muthu Senthil; Ramasamy, P.

2018-04-01

The semi-organic single crystal of piperazinium tetrachlorozincate monohydrate (PTCZ) was successfully grown by slow evaporation solution technique (SEST). The grown crystal was subjected to the single crystal XRD studies for confirming the unit cell parameters. The optical quality of the grown crystal was identified by the UV-Vis NIR spectrum analysis and the optical band gap energy was calculated. The photoconductivity study reveals that the grown crystal has positive photoconductive nature. The mechanical stability of the grown crystal was analyzed using Vickers microhardness analyzer. The third-order nonlinear optical properties such as nonlinear refractive index (n2), absorption co-efficient (β) and susceptibility (χ(3)) were studied by Z-scan technique at 640 nm using solid state laser.

Crystalline perfection and optical studies of L-Histidinium dihydrogen phosphate orthophosphoric acid (LHDP) single crystals

NASA Astrophysics Data System (ADS)

Ittyachan, Reena; Arunkumar, A.; Bhagavannarayana, G.

2015-10-01

Single crystals of L-Histidinium dihydrogenphosphate orthophosphoric acid (LHDP) were grown by slow evaporation solution growth technique. The grown crystals were confirmed by single crystal X-ray diffraction techniques. The HRXRD rocking curve measurements revealed the crystalline perfection of grown crystal and the absence of structural grain boundaries. The lower optical cut-off wavelength for this crystal was observed at 240 nm. The third order nonlinear refractive index (n2), nonlinear absorption coefficient (β) and susceptibility (χ(3)) were calculated by Z-scan studies using Nd: YAG laser as a source. The single shot laser damage threshold of grown crystal was measured to be 6.286 GW/cm2 using Nd: YAG laser.

Growth and characterization of organic NLO material: Clobetasol propionate

NASA Astrophysics Data System (ADS)

Purusothaman, R.; Rajesh, P.; Ramasamy, P.

2015-06-01

Single crystals of clobetasol propionate (CP) have been grown by slow evaporation solution technique using mixed solvent of methanol-acetone. The grown crystals were subjected to single crystal X-ray diffraction analysis to confirm their lattice parameter and space group. The powder X-ray diffraction pattern of the grown CP has been indexed. Thermal analysis was performed to study the thermal stability of the grown crystals. Photoluminescence spectrum shows broad emission peak observed at 421 nm. Nonlinear optical studies were carried out for the grown crystal and second harmonic generation (SHG) efficiency was found in the crystal.

Growth and characterization of new semiorganic nonlinear optical and piezoelectric lithium sulfate monohydrate oxalate single crystals

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

Yadav, Harsh; Sinha, Nidhi; Kumar, Binay, E-mail: b3kumar69@yahoo.co.in

2015-04-15

Highlights: • A new semiorganic single crystal of LSO grown by slow evaporation technique. • Morphological studies of the LSO crystal deduced by BFDH law. • In the UV–vis spectrum wide transparent region and large band gap were found. • SHG is equal to KDP crystal and d{sub 33} was found to be equal to 6pC/N. • Grown crystal belongs to softer category. - Abstract: New semiorganic crystal of lithium sulfate monohydrate oxalate (LSO) for nonlinear application was synthesized by controlled slow evaporation method. The growth rate of various planes of the grown crystal was estimated by morphological study. Singlemore » crystal XRD analysis confirmed that the crystal belongs to triclinic lattice with space group P1. High transparency (∼95%) with large band gap (4.57 eV) was analyzed by UV–vis studies. FTIR and Raman spectroscopy were used to identify various functional groups present in the LSO crystal. SHG efficiency was found to be equal to the KDP crystal. Thermal stability (up to 117.54 °C) and melting point (242 °C) of the crystal were studied by TG-DTA. In dielectric measurements, the value of dielectric constant decreases with increase in frequency. Hardness studies confirmed soft nature of crystals. The piezoelectric coefficient was found to be 6pC/N along [0 0 1].« less

Evaporation of inclined water droplets.

PubMed

Kim, Jin Young; Hwang, In Gyu; Weon, Byung Mook

2017-02-16

When a drop is placed on a flat substrate tilted at an inclined angle, it can be deformed by gravity and its initial contact angle divides into front and rear contact angles by inclination. Here we study on evaporation dynamics of a pure water droplet on a flat solid substrate by controlling substrate inclination and measuring mass and volume changes of an evaporating droplet with time. We find that complete evaporation time of an inclined droplet becomes longer as gravitational influence by inclination becomes stronger. The gravity itself does not change the evaporation dynamics directly, whereas the gravity-induced droplet deformation increases the difference between front and rear angles, which quickens the onset of depinning and consequently reduces the contact radius. This result makes the evaporation rate of an inclined droplet to be slow. This finding would be important to improve understanding on evaporation dynamics of inclined droplets.

Evaporation of inclined water droplets

PubMed Central

Kim, Jin Young; Hwang, In Gyu; Weon, Byung Mook

2017-01-01

When a drop is placed on a flat substrate tilted at an inclined angle, it can be deformed by gravity and its initial contact angle divides into front and rear contact angles by inclination. Here we study on evaporation dynamics of a pure water droplet on a flat solid substrate by controlling substrate inclination and measuring mass and volume changes of an evaporating droplet with time. We find that complete evaporation time of an inclined droplet becomes longer as gravitational influence by inclination becomes stronger. The gravity itself does not change the evaporation dynamics directly, whereas the gravity-induced droplet deformation increases the difference between front and rear angles, which quickens the onset of depinning and consequently reduces the contact radius. This result makes the evaporation rate of an inclined droplet to be slow. This finding would be important to improve understanding on evaporation dynamics of inclined droplets. PMID:28205642

A novel organic nonlinear optical crystal: Creatininium succinate

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

Thirumurugan, R.; Anitha, K., E-mail: singlecerystalxrd@gmail.ciom

2015-06-24

A novel organic material complex of creatininium succinate (CS) has been synthesized and single crystals were grown by the reaction of creatinine and succinic acid from aqueous solution by employing the technique of slow evaporation at room temperature. The structure of the grown crystal has been elucidated using single crystal X-ray diffraction analysis and the structure was refined by least-squares method to R = 0.027 for 1840 reflections. FT-IR spectral investigation has been carried out to identify the various functional groups in the title compound. UV–Vis transmission was carried out which shows the crystal has a good optical transmittance inmore » the visible region with lower cutoff wavelength around 220 nm. Nonlinear optical property of the crystal was confirmed by Kurtz-Perry powder technique.« less

Crystal growth of triphenylphosphine oxide 4-nitrophenol (TP4N) for nonlinear optical (NLO) applications

NASA Astrophysics Data System (ADS)

Pandian, Muthu Senthil; Karuppasamy, P.; Kamalesh, T.; Ramasamy, P.; Verma, Sunil

2018-04-01

The optically good quality organic single crystals of triphenylphosphine oxide 4-nitrophenol (TP4N) were successfully grown by slow evaporation solution technique (SEST) using methanol as solvent. The lattice parameters of the grown crystal were confirmed by single crystal X-ray diffraction analysis. The optical transmittance, cut-off wavelength and band gap of the TP4N crystal were obtained by UV-Vis NIR spectrum analysis. The photoluminescence studies were carried out to find out the luminesce properties of TP4N single crystal. The photoconductivity studies reveal that the TP4N crystal has negative photoconductive nature. The third order nonlinear susceptibility (χ(3)) of TP4N crystal was evaluated using the Z-scan technique at 640 nm.

Growth and characterization of organic material 4-dimethylaminobenzaldehyde single crystal.

PubMed

Jebin, R P; Suthan, T; Rajesh, N P; Vinitha, G; Madhusoodhanan, U

2015-01-25

The organic material 4-dimethylaminobenzaldehyde single crystals were grown by slow evaporation technique. The grown crystal was confirmed by the single crystal and powder X-ray diffraction analyses. The functional groups of the crystal have been identified from the Fourier Transform Infrared (FTIR) and FT-Raman studies. The optical property of the grown crystal was analyzed by UV-Vis-NIR and photoluminescence (PL) spectral measurements. The thermal behavior of the grown crystal was analyzed by thermogravimetric (TG) and differential thermal analyses (DTA). Dielectric measurements were carried out with different frequencies by using parallel plate capacitor method. The third order nonlinear optical properties of 4-dimethylaminobenzaldehyde was measured by the Z-scan technique using 532 nm diode pumped continuous wave (CW) Nd:YAG laser. Copyright © 2014 Elsevier B.V. All rights reserved.

Growth, optical, ICP and thermal studies of nonlinear optical single crystal: Sodium acid phthalate (NaAP)

NASA Astrophysics Data System (ADS)

Mahadevan, M.; Arivanandhan, M.; Elangovan, K.; Anandan, P.; Ramachandran, K.

2017-07-01

Good quality single crystals of sodium acid phthalate (NaAP) were grown by slow evaporation technique. Single crystal X-ray diffraction study of the grown crystal reveals that the crystal belongs to orthorhombic system with space group B2ab. Fourier transform infrared spectrum confirms the presence of the functional groups of the grown material. Inductively coupled plasma emission spectroscopy analysis is used to confirm the presence of Na element in the sample. Thermal analysis of the NaAP crystal shows that the crystal is stable up to 140°C. Optical transmittance of the grown crystal was recorded in the wavelength range from 200 and 800 nm using UV-Vis-NIR spectrophotometer. The second harmonic generation of NaAP was analysed using Kurtz powder technique.

Growth and characterization of Cadmium Thiosemicarbazide Bromide crystals for antibacterial and nonlinear optical applications

NASA Astrophysics Data System (ADS)

Thomas Joseph Prakash, J.; Martin Sam Gnanaraj, J.

2015-01-01

Semiorganic nonlinear optical crystals of Cadmium Thiosemicarbazide Bromide was grown by slow evaporation solution growth technique. The unit cell parameters were estimated by subjecting the crystals to single crystal X-ray diffraction. The grown crystals were subjected to Powder X-ray diffraction for analyzing the crystalline nature of the sample. FTIR studies reveal the functional groups and the optical characters were analyzed by UV-Vis spectral studies. Mechanical stability of the sample was assessed by Vicker's micro hardness test. The presence of surface dislocations was identified by chemical etching technique. Antibacterial study was carried out against ACDP declared harmful pathogens. SHG efficiency of CTSB crystal was tested using Nd: YAG laser and it was found to be ∼1.8 times that of potassium dihydrogen phosphate.

Effect of amaranth dye on the growth and properties of conventional and SR method grown KAP single crystals

NASA Astrophysics Data System (ADS)

Babu Rao, G.; P., Rajesh; Ramasamy, P.

2018-04-01

The 0.1 mol% amaranth added KAP single crystals were grown from aqueous solutions by both slow evaporation solution technique and Sankaranarayanan-Ramasamy method. The single crystal having dimension of 45 mm length and 12 mm diameter was grown with growth rate of 1.5 mm/day using SR method. 87 % transmittance is obtained for SR method grown amaranth added KAP single crystal. The high intense luminescence at 661 nm is obtained from amaranth added conventional and SR method grown KAP single crystal. The amaranth added KAP single crystal possesses good mechanical and laser damage threshold stability.

Improved ferroelectric and pyroelectric parameters in iminodiacetic acid doped TGS crystal

NASA Astrophysics Data System (ADS)

Rai, Chitharanjan; Sreenivas, K.; Dharmaprakash, S. M.

2010-01-01

Single crystals of Iminodiacetic acid (HN(CH 2COOH) 2) doped Triglycine sulphate (IDATGS) has been grown from aqueous solution at constant temperature by slow evaporation technique. The concentration of the dopant in the TGS solution was 2 mol%. The X-ray diffraction analysis indicates that there is significant change in the lattice parameters compared to pure TGS crystal. The IDATGS crystal has larger transition temperature and observed higher and uniform figure of merit over most part of the ferroelectric phase. These crystals also exhibit higher internal bias field and micro-hardness number compared to pure TGS. Therefore IDATGS may be a potential material for IR detectors.

Crystal growth, structural, optical, dielectric and thermal studies of an amino acid based organic NLO material: L-Phenylalanine L-phenylalaninium malonate

NASA Astrophysics Data System (ADS)

Prakash, M.; Geetha, D.; Lydia Caroline, M.; Ramesh, P. S.

2011-12-01

Good transparent single crystals of L-phenylalanine L-phenylalaninium malonate (LPPMA) have been grown successfully by slow evaporation technique from aqueous solution. Single crystal X-ray diffractometer was utilized to measure unit cell parameter and to confirm the crystal structure. The chemical structure of compound was established by FT-NMR technique. The vibrational modes of the molecules of elucidated from FTIR spectra. Its optical behaviour has been examined by UV-vis spectral analysis, which shows the absence of absorbance in the visible region. Thermal properties of the LPPMA crystal were carried out by thermo gravimetric analysis (TGA) and differential thermal analysis (DTA) techniques, which indicate that the material does not decompose before melting. The melting point of grown crystal was observed as 180 °C by melting point apparatus. The NLO property was confirmed by the powder technique of Kurtz and Perry. The dielectric behaviour of the sample was also studied for the first time.

Evaporation of nanoscale water on a uniformly complete wetting surface at different temperatures.

PubMed

Guo, Yuwei; Wan, Rongzheng

2018-05-03

The evaporation of nanoscale water films on surfaces affects many processes in nature and industry. Using molecular dynamics (MD) simulations, we show the evaporation of a nanoscale water film on a uniformly complete wetting surface at different temperatures. With the increase in temperature, the growth of the water evaporation rate becomes slow. Analyses show that the hydrogen bond (H-bond) lifetimes and orientational autocorrelation times of the outermost water film decrease slowly with the increase in temperature. Compared to a thicker water film, the H-bond lifetimes and orientational autocorrelation times of a monolayer water film are much slower. This suggests that the lower evaporation rate of the monolayer water film on a uniformly complete wetting surface may be caused by the constriction of the water rotation due to the substrate. This finding may be helpful for controlling nanoscale water evaporation within a certain range of temperatures.

Numerical simulation and stability analysis of solutocapillary effect in ultrathin films

NASA Astrophysics Data System (ADS)

Gordeeva, V. Yu.; Lyushnin, A. V.

2017-04-01

Polar fluids, like water or polydimethylsiloxane, are widely used in technical and medical applications. Capillary effects arising from surface tension gradients can be significant in thin liquid films. The present paper is dedicated to investigation of capillary flow due to a surfactant added to a polar liquid under conditions when intermolecular forces and disjoining pressure play an important role. Evolution equations are formulated for a film profile and the surfactant concentration. Stability analysis shows that the Marangoni effect destabilizes the film, and oscillatory modes appear at slow evaporation rates. We find that the film has four stability modes of at slow evaporation: monotonic stable, monotonic unstable, oscillatory stable, and oscillatory unstable, depending on the wave number of disturbances.

Passivation of surface states in the ZnO nanowire with thermally evaporated copper phthalocyanine for hybrid photodetectors.

PubMed

Chen, Qi; Ding, Huaiyi; Wu, Yukun; Sui, Mengqiao; Lu, Wei; Wang, Bing; Su, Wenming; Cui, Zheng; Chen, Liwei

2013-05-21

The adsorption of O2/H2O molecules on the ZnO nanowire (NW) surface results in the long lifetime of photo-generated carriers and thus benefits ZnO NW-based ultraviolet photodetectors by suppressing the dark current and improving the photocurrent gain, but the slow adsorption process also leads to slow detector response time. Here we show that a thermally evaporated copper phthalocyanine film is effective in passivating surface trap states of ZnO NWs. As a result, the organic/inorganic hybrid photodetector devices exhibit simultaneously improved photosensitivity and response time. This work suggests that it could be an effective way in interfacial passivation using organic/inorganic hybrid structures.

Thermal, Dielectric Studies on Pure and Amino Acid L-Glutamic Acid, L-Histidine L-Valine Doped Potassium Dihydrogen Phosphate Single Crystals

NASA Astrophysics Data System (ADS)

Kumaresan, P.; Babu, S. Moorthy; Anbarasan, P. M.

Amino acids (L-Glutamic acid, L-Histidine, L-Valine) doped potassium dihydrogen phosphate crystals were grown by the solution growth technique. Slow cooling as well as slow evaporation methods were employed to grow these crystals. The concentration of dopants in the mother solution was varied from 0.1 mole % to 10 mole %. The solubility data for all dopant concentrations were determined. The variation in pH and the corresponding habit modification of the grown crystals were characterized with UV - VIS, FT-IR and SHG trace elements, and dielectric studies reveal slight distortion of lattice parameter for the heavily doped KDP crystals. TGA-DTA studies reveal good thermal stability. The dopants increase the hardness value of the material, which also depends on the concentration of the dopants. Amino acids doping improved the NLO properties. The detailed results on the spectral parameters, habit modifications and constant values will be presented.

Investigations on nucleation, HRXRD, optical, piezoelectric, polarizability and Z-scan analysis of L-arginine maleate dihydrate single crystals

NASA Astrophysics Data System (ADS)

Sakthy Priya, S.; Alexandar, A.; Surendran, P.; Lakshmanan, A.; Rameshkumar, P.; Sagayaraj, P.

2017-04-01

An efficient organic nonlinear optical single crystal of L-arginine maleate dihydrate (LAMD) has been grown by slow evaporation solution technique (SEST) and slow cooling technique (SCT). The crystalline perfection of the crystal was examined using high-resolution X-ray diffractometry (HRXRD) analysis. Photoluminescence study confirmed the optical properties and defects level in the crystal lattice. Electromechanical behaviour was observed using piezoelectric co-efficient (d33) analysis. The photoconductivity analysis confirmed the negative photoconducting nature of the material. The dielectric constant and loss were measured as a function of frequency with varying temperature and vice-versa. The laser damage threshold (LDT) measurement was carried out using Nd:YAG Laser with a wavelength of 1064 nm (Focal length is 35 cm) and the obtained results showed that LDT value of the crystal is high compared to KDP crystal. The high laser damage threshold of the grown crystal makes it a potential candidate for second and higher order nonlinear optical device application. The third order nonlinear optical parameters of LAMD crystal is determined by open-aperture and closed-aperture studies using Z-scan technique. The third order linear and nonlinear optical parameters such as the nonlinear refractive index (n2), two photon absorption coefficient (β), Real part (Reχ3) and imaginary part (Imχ3) of third-order nonlinear optical susceptibility are calculated.

Crystal growth, structural, optical, mechanical and thermal properties of a new nonlinear optical single crystal: L-Ornithine monohydrochloride.

PubMed

Balakrishnan, T; Ramamurthi, K

2009-03-01

Amino acid family crystals exhibit excellent nonlinear optical and electro optical properties. l-Ornithine monohydrochloride single crystal, belongs to the amino acid group, was grown by the slow evaporation solution growth technique at room temperature. The grown crystals were characterized by single crystal and powder X-ray diffraction analysis, Fourier transform infrared (FTIR) spectroscopy, TGA, DTA and DSC analyses. UV-vis-NIR spectrum shows excellent transmission in the UV, visible and NIR region (300-1600nm). The mechanical properties of grown crystals were studied using Vickers microhardness tester. Its second harmonic generation efficiency was tested using Nd:YAG laser and is 1.25 times that of KDP.

Synthesis, growth, structural and optical studies of a novel organic Piperazine (bis) p-toluenesulfonate single crystal.

PubMed

Rekha, P; Peramaiyan, G; NizamMohideen, M; Kumar, R Mohan; Kanagadurai, R

2015-03-15

A novel organic single crystal of Piperazinium (bis) p-toluenesulfonate (PPTS) was grown by a slow evaporation solution growth technique. The structure of the grown crystal was determined using single crystal X-ray diffraction analysis. The PPTS crystal belongs to the triclinic crystal system with space group of P1¯. The presence of functional groups was confirmed by FTIR spectral analysis. The optical transmittance range and cut-off wavelength were identified by UV-vis-NIR spectral studies. The luminescent properties of PPTS crystal were investigated. The thermal behavior of PPTS crystal was studied by TG-DT analyses. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis, crystal structure, thermal and nonlinear optical properties of new metal-organic single crystal: Tetrabromo (piperazinium) zincate (II) (TBPZ)

NASA Astrophysics Data System (ADS)

Boopathi, K.; Babu, S. Moorthy; Ramasamy, P.

2018-04-01

Tetrabromo (piperazinium) zincate, a new metal-organic crystal has been synthesized and its single crystal grown by slow evaporation method. The grown crystal has characterized by structural, spectral, thermal, linear and nonlinear optical properties. Single crystal X-ray diffractions study reveals that grown crystal belongs to orthorhombic crystal system with space group P212121. The presence of functional groups is identified by FT-IR spectral analysis. Thermal stability of the crystal was ascertained by TG-DTA measurement. The second order harmonic generation efficiency was measured using Kurtz and Perry technique and it was found to be 1.5 times that of KDP.

Linear, non-linear and thermal properties of single crystal of LHMHCl

NASA Astrophysics Data System (ADS)

Kulshrestha, Shobha; Shrivastava, A. K.

2018-05-01

The single crystal of amino acid of L-histidine monohydrochloride was grown by slow evaporation technique at room temperature. High optical quality and appropriate size of crystals were grown under optimized growth conditions. The grown crystals were transparent. Crystals are characterized with different characterizations such as Solubility test, UV-Visible, optical band gap (Eg). With the help of optical data to be calculate absorption coefficient (α), extinction coefficient (k), refractive index (n), dielectric constant (ɛ). These optical constants are shows favorable conditions for photonics devices. Second harmonic generation (NLO) test show the green light emission which is confirm that crystal have properties for laser application. Thermal stability of grown crystal is confirmed by TG/DTA.

Structural, spectral and birefringence studies of semiorganic nonlinear optical single crystal: Calcium5-sulfosalicylate

NASA Astrophysics Data System (ADS)

Shalini, D.; Kalainathan, S.; Ambika, V. Revathi; Hema, N.; Jayalakshmi, D.

2017-11-01

Semi-organic nonlinear optical crystal Calcium5-Sulfosalicylate (CA5SS) was grown by slow evaporation solution growth technique. The cell parameters and molecular structure of the grown crystal were studied by single crystal x-ray diffraction analysis. The presence of various functional groups of the grown crystal was confirmed using Fourier transform infrared (FT-IR), Fourier transform Raman (FT-Raman) analysis. UV-Visible spectrum shows that CA5SS crystals have high transmittance in the range of 330-900 nm. The refractive index, birefringence and transient photoluminescence properties of the grown crystal were analyzed. The frequency doubling of the grown crystal (CA5SS) were studied and compared with that of KDP.

Thermal, mechanical, optical and dielectric properties of piperazinium hydrogen phosphite monohydrate NLO single crystal

NASA Astrophysics Data System (ADS)

Rajkumar, R.; Praveen Kumar, P.

2018-05-01

Optical transparent crystal of piperazinium hydrogen phosphite monohydrate (PHPM) was grown by slow evaporation method. The grown crystal was characterized by single crystal X-ray diffraction analysis and the crystal belongs to monoclinic system. The functional groups present in PHPM crystal were confirmed by FTIR analysis. UV-Visible spectrum shows that the PHPM crystal is transparent in the visible region. The mechanical behavior of PHPM crystal was characterized by Vickers hardness test. Thermal stability of PHPM crystal was analyzed by thermogravimetric analysis. Dielectric studies were also carried out for the grown crystal. The third-order nonlinear parameters such as nonlinear refractive index and nonlinear absorption coefficient have been calculated using Z scan technique.

Issues Related to Cleaning Complex Geometry Surfaces with ODC-Free Solvents

NASA Technical Reports Server (NTRS)

Bradford, Blake F.; Wurth, Laura A.; Nayate, Pramod D.; McCool, Alex (Technical Monitor)

2001-01-01

Implementing ozone depleting chemicals (ODC)-free solvents into full-scale reusable solid rocket motor cleaning operations has presented problems due to the low vapor pressures of the solvents. Because of slow evaporation, solvent retention is a problem on porous substrates or on surfaces with irregular geometry, such as threaded boltholes, leak check ports, and nozzle backfill joints. The new solvents are being evaluated to replace 1,1,1-trichloroethane, which readily evaporates from these surfaces. Selection of the solvents to be evaluated on full-scale hardware was made based on results of subscale tests performed with flat surface coupons, which did not manifest the problem. Test efforts have been undertaken to address concerns with the slow-evaporating solvents. These concerns include effects on materials due to long-term exposure to solvent, potential migration from bolthole threads to seal surfaces, and effects on bolt loading due to solvent retention in threads. Tests performed to date have verified that retained solvent does not affect materials or hardware performance. Process modifications have also been developed to assist drying, and these can be implemented if additional drying becomes necessary.

Method for improving accuracy in full evaporation headspace analysis.

PubMed

Xie, Wei-Qi; Chai, Xin-Sheng

2017-05-01

We report a new headspace analytical method in which multiple headspace extraction is incorporated with the full evaporation technique. The pressure uncertainty caused by the solid content change in the samples has a great impact to the measurement accuracy in the conventional full evaporation headspace analysis. The results (using ethanol solution as the model sample) showed that the present technique is effective to minimize such a problem. The proposed full evaporation multiple headspace extraction analysis technique is also automated and practical, and which could greatly broaden the applications of the full-evaporation-based headspace analysis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis, crystal growth and characterization of a phase matchable nonlinear optical single crystal: p-chloro dibenzylideneacetone

NASA Astrophysics Data System (ADS)

Ravindra, H. J.; John Kiran, A.; Nooji, Satheesha Rai; Dharmaprakash, S. M.; Chandrasekharan, K.; Kalluraya, Balakrishna; Rotermund, Fabian

2008-05-01

Good quality single crystals of p-chloro dibenzylideneacetone (CDBA) of size 13 mm×8 mm×2 mm were grown by slow evaporation solution growth technique. The grown crystals were confirmed by elemental analysis, Fourier transform infrared (FTIR) analysis and single crystal X-ray diffraction techniques. From the thermo gravimetric/differential thermal (TG/DT) analysis, the CDBA was found to be thermally stable up to 250 °C. The mechanical stability of the crystal is comparable with that of the other reported chalcones. The lower optical cut-off wavelength for this crystal was observed at 440 nm. The laser damage threshold of the crystal was 0.6 GW/cm 2 at 532 nm. The second harmonic generation conversion efficiency of the powder sample of CDBA was found to be 4.5 times greater than that of urea. We also demonstrate the existence of the phase matching property in this crystal using Kurtz powder technique.

Evaporation of Sunscreen Films: How the UV Protection Properties Change.

PubMed

Binks, Bernard P; Brown, Jonathan; Fletcher, Paul D I; Johnson, Andrew J; Marinopoulos, Ioannis; Crowther, Jonathan M; Thompson, Michael A

2016-06-01

We have investigated the evaporation of thin sunscreen films and how the light absorption and the derived sun protection factor (SPF) change. For films consisting of solutions of common UV filters in propylene glycol (PG) as solvent, we show how evaporation generally causes three effects. First, the film area can decrease by dewetting leading to a transient increase in the average film thickness. Second, the film thins by evaporative loss of the solvent. Third, precipitation of the UV filter occurs when solvent loss causes the solubility limit to be reached. These evaporation-induced changes cause the UV absorbance of the film to decrease with resultant loss of SPF over the time scale of the evaporation. We derive an approximate model which accounts semiquantitatively for the variation of SPF with evaporation. Experimental results for solutions of different UV filters on quartz, different skin mimicking substrates, films with added nanoparticles, films with an added polymer and films with fast-evaporating decane as solvent (instead of slow evaporating PG) are discussed and compared with model calculations. Addition of either nanoparticles or polymer suppress film dewetting. Overall, it is hoped that the understanding gained about the mechanisms whereby film evaporation affects the SPF will provide useful guidance for the formulation of more effective sunscreens.

Synthesis, crystal growth and studies on non-linear optical property of new chalcones

NASA Astrophysics Data System (ADS)

Sarojini, B. K.; Narayana, B.; Ashalatha, B. V.; Indira, J.; Lobo, K. G.

2006-09-01

The synthesis, crystal growth and non-linear optical (NLO) property of new chalcone derivatives are reported. 4-Propyloxy and 4-butoxy benzaldehydes were made to under go Claisen-Schmidt condensation with 4-methoxy, 4-nitro and 4-phenoxy acetophenones to form corresponding chalcones. The newly synthesized compounds were characterized by analytical and spectral data. The Second harmonic generation (SHG) efficiency of these compounds was measured by powder technique using Nd:YAG laser. Among tested compounds three chalcones showed NLO property. The chalcone 1-(4-methoxyphenyl)-3-(4-propyloxy phenyl)-2-propen-1-one exhibited SHG conversion efficiency 2.7 times that of urea. The bulk crystal of 1-(4-methoxyphenyl)-3-(4-butoxyphenyl)-2-propen-1-one (crystal size 65×28×15 mm 3) was grown by slow-evaporation technique from acetone. Microhardness of the crystal was tested by Vicker's microhardness method.

Crystal structure, thermal and optical properties of Benzimidazole benzimidazolium picrate crystal

NASA Astrophysics Data System (ADS)

Jagadesan, A.; Peramaiyan, G.; Srinivasan, T.; Kumar, R. Mohan; Arjunan, S.

2016-02-01

A new organic framework of benzimidazole with picric acid has been synthesized. A single crystal with a size of 38×10×4 mm3 was grown by a slow evaporation solution growth technique. X-ray diffraction study revealed that the BZP crystal belongs to triclinic system with space group P-1. High resolution X-ray diffraction study shows the absence of grain boundaries without any defects. The thermal stability and specific heat capacity of BZP were investigated by TG/DT and TG/DSC analyses. From the UV-vis-NIR spectral study, optical transmission window and band gap of BZP were found out. The nonlinear refractive index (n2) and third order susceptibility Re(χ(3)) values of BZP crystal are estimated to be 1.73×10-7 cm2/W and 1.26×10-5 esu, respectively using a Z-scan technique.

Effects of Evaporation/Condensation on Spreading and Contact Angle of a Volatile Liquid Drop

NASA Technical Reports Server (NTRS)

Zhang, Nengli; Chao, David F.; Singh, Bhim S. (Technical Monitor)

2000-01-01

Effects of evaporation/condensation on spreading and contact angle were experimentally studied. A sessile drop of R-113 was tested at different vapor environments to determine the effects of evaporation/condensation on the evolution of contact diameter and contact angle of the drop. Condensation on the drop surface occurs at both the saturated and a nonsaturated vapor environments and promotes the spreading. When the drop is placed in the saturated vapor environment it tends to completely wetting and spreads rapidly. In a nonsaturated vapor environment, the evolution of the sessile drop is divided three stages: condensation-spreading stage, evaporation-retracting stage and rapid contracting stage. In the first stage the drop behaves as in the saturated environment. In the evaporation -retracting stage, the competition between spreading and evaporation of the drop determines the evolution characteristics of the contact diameter and the contact angle. A lower evaporation rate struggles against the spreading power to turn the drop from spreading to retracting with a continuous increase of the contact angle. The drop placed in open air has a much higher evaporation rate. The strong evaporation suppresses the spreading and accelerates the retraction of the drop with a linear decrease of the contact diameter. The contraction of the evaporating drops is gradually accelerated when the contact diameter decreases to 3 min and less till drying up, though the evaporation rate is gradually slowing down.

Synthesis, growth, structural characterization, Hirshfeld analysis and nonlinear optical studies of a methyl substituted chalcone

NASA Astrophysics Data System (ADS)

Prabhu, Shobha R.; Jayarama, A.; Chandrasekharan, K.; Upadhyaya, V.; Ng, Seik Weng

2017-05-01

A new chalcone compound (2E)-3-(3-methylphenyl)-1-(4-nitrophenyl)prop-2-en-1-one (3MPNP) with molecular formula C16H13NO3 has been synthesized and crystallized by slow solvent evaporation technique. The Fourier transform infrared, Fourier transform Raman and nuclear magnetic resonance techniques were used for structural characterization. UV-visible absorption studies were carried out to study the transparency of the crystal in the visible region. Differential scanning calorimetry study shows thermal stability of crystals up to temperature 122 °C. Single crystal X-ray diffraction and powder X-ray diffraction techniques were used to study crystal structure and cell parameters. The Hirshfeld surface and 2-D fingerprint analysis were performed to study the nature of interactions and their quantitative contributions towards the crystal packing. The third order non-linear optical properties have been studied using single beam Z-scan technique and the results show that the material is a potential candidate for optical device applications such as optical limiters and optical switches.

Crystal growth, structural, optical, dielectric and thermal studies of an amino acid based organic NLO material: L-phenylalanine L-phenylalaninium malonate.

PubMed

Prakash, M; Geetha, D; Caroline, M Lydia; Ramesh, P S

2011-12-01

Good transparent single crystals of L-phenylalanine L-phenylalaninium malonate (LPPMA) have been grown successfully by slow evaporation technique from aqueous solution. Single crystal X-ray diffractometer was utilized to measure unit cell parameter and to confirm the crystal structure. The chemical structure of compound was established by FT-NMR technique. The vibrational modes of the molecules of elucidated from FTIR spectra. Its optical behaviour has been examined by UV-vis spectral analysis, which shows the absence of absorbance in the visible region. Thermal properties of the LPPMA crystal were carried out by thermo gravimetric analysis (TGA) and differential thermal analysis (DTA) techniques, which indicate that the material does not decompose before melting. The melting point of grown crystal was observed as 180°C by melting point apparatus. The NLO property was confirmed by the powder technique of Kurtz and Perry. The dielectric behaviour of the sample was also studied for the first time. Copyright © 2011 Elsevier B.V. All rights reserved.

Real-time direct measurement of liquid (water) evaporation by simple disturbance inhibited interfometry technique

NASA Astrophysics Data System (ADS)

Kim, Yong Gi

2017-11-01

A real-time in-situ interferometry method was proposed to measure water (liquid) evaporation directly over the liquid surface inside the reservoir. The direct evaporation measurement relied on the counting the number of sinusoidal fringes. As the water inside reservoir evaporated, the depth of the water decreases a little thus the optical path length changes. Evaporation signals have been determined as a function of the focusing beam position of the signal beam over the liquid surface. In interferometry technique, the most limiting factors are surface disturbances and vibrations over the liquid surface. This limiting factor was simply inhibited by placing a long cylindrical aluminum tube around the signal beam of the interferometer over the liquid surface. A small diameter cylindrical Al tube diminished vibrations and wind induced surface ripples more effectively than that of the larger one. Water evaporation was successfully measured in real-time with a warm water and cold water even under windy condition with an electric fan. The experimental results demonstrated that the interferometry technique allows determining of liquid evaporation in real-time. Interferometric technique opens up a new possibility of methodology for liquid evaporation measurement even in several environmental disturbances, such as, vibration, surface disturbance, temperature change and windy environments.

Growth, structural, spectral, optical, and thermal studies on amino acid based new NLO single crystal: L-phenylalanine-4-nitrophenol.

PubMed

Prakash, M; Lydia Caroline, M; Geetha, D

2013-05-01

A new organic nonlinear optical single crystal, L-phenylalanine-4-nitrophenol (LPAPN) belonging to the amino acid group has been successfully grown by slow evaporation technique. The lattice parameters of the grown crystal have been determined by X-ray diffraction studies. FT-IR spectrum was recorded to identify the presence of functional group and molecular structure was confirmed by NMR spectrum. Thermal strength of the grown crystal has been studied using TG-DTA analyses. The grown crystals were found to be transparent in the entire visible region. The existence of second harmonic generation signals was observed using Nd:YAG laser with fundamental wavelength of 1064 nm. Copyright © 2013 Elsevier B.V. All rights reserved.

Crystalline perfection, optical and piezoelectric properties of a novel semi-organic single crystal: Zinc guanidinium sulphate

NASA Astrophysics Data System (ADS)

Nandhini, S.; Murugakoothan, P.

2018-04-01

Zinc Guanidinium Sulfate (ZGuS), a semi-organic single crystal, was synthesized using slow evaporation solution growth technique. It is a non-centrosymmetric crystal with space group I4 ¯2d . The crystalline nature of the crystal and the strain were determined using powder X-ray diffraction analysis. The crystalline perfection of the grown crystal was revealed using HR-XRD analysis. The UV-vis-NIR transmittance spectrum depicts 60% transparency with lower-cut off wavelength of 210 nm. The emission spectrum of the crystal was determined using photoluminescence study. Piezoelectricity was confirmed by determining the piezoelectric charge coefficient (d33). These findings shows that the title compound can be employed for photonic and transducer applications.

Growth, piezoelectric study and particle size dependent SHG of an 80 mm long SR grown imidazolium l-tartrate single crystals

NASA Astrophysics Data System (ADS)

Jauhar, RO MU; Era, Paavai; Murugakoothan, P.

2018-05-01

Single crystal of imidazolium l-tartrate (IMLT), an organic nonlinear optical material, was successfully grown by slow evaporation solution growth technique (SEST) and Sankaranarayanan - Ramasamy (SR) method. The crystal structure and its lattice parameters were confirmed by single crystal X-ray diffraction study. The IMLT crystal belongs to monoclinic crystal system having a = 7.579(6) Å, b = 6.911(4) Å, c = 8.9281(5) Å, β = 101.45(8)°, volume, V = 458.33 Å3. The d33 coefficient found from the the piezoelectric study is 23 pC/N. The relative second harmonic generation efficiency of IMLT was found to be 3.16 times that of reference KDP material.

Supramolecular assembly in the epiisopiloturine hydrochloride salt

NASA Astrophysics Data System (ADS)

Mafud, Ana Carolina; Reinheimer, Eric W.; Lima, Filipe Camargo Dalmatti Alves; Batista, Larissa Fernandes; de Paula, Karina; Véras, Leiz Maria Costa; de Souza de Almeida Leite, José Roberto; Venancio, Tiago; Mascarenhas, Yvonne Primerano

2017-05-01

Epiisopiloturine hydrochloride (Epi-HCl) salt was synthetized from epiisopiloturine, an in vivo anthelmintic compound against Schistosoma mansoni worms. Despite there being no acute toxicity in mammalian cells, the compound's water insolubility makes its administration difficult. In this communication, we report the characterization of Epi-HCl its features by spectroscopy, thermal analysis, and PXRD. The single crystals suitable to X-ray diffraction were grown by slow evaporation technique. To better understand the nature of Epi-HCl' solid state, SS-NMR was also used. The salt's intramolecular structure was maintained via cation-pi intramolecular interactions, which in conjunction with hydrogen bonding, gives rise to an extended supramolecular assembly. The interatomic distances within the cations and environment around the chloride anion vary as function of temperature, suggesting a packing relaxation.

Effect of amino acid dopants on the spectral, optical, mechanical and thermal properties of potassium acid phthalate crystals for possible optoelectronic and frequency doubling applications

NASA Astrophysics Data System (ADS)

Prakash, J. Thomas Joseph; Gnanaraj, J. Martin Sam; Dhavud, S. Shek; Ekadevasena, S.

2015-09-01

Undoped and amino acid (L-Arginine and L-Valine) doped KAP crystals were grown by slow evaporation solution growth technique. The changes in the structural, spectral, optical, mechanical and thermal properties were observed. The sharp prominent peaks in the indexed powder XRD pattern confirms the crystalline nature of the sample. Optical studies reveal that the crystal is transparent in the entire visible light region. Thermal stability was checked by TG/DTA analysis. The mechanical stability was evaluated from Vicker's microhardness test. The SHG efficiency for the title materials was tested with different particle sizes by the Kurtz and Perry powder method, which established the existence of phase matching.

Optimized evaporation technique for leachate treatment: Small scale implementation.

PubMed

Benyoucef, Fatima; Makan, Abdelhadi; El Ghmari, Abderrahman; Ouatmane, Aziz

2016-04-01

This paper introduces an optimized evaporation technique for leachate treatment. For this purpose and in order to study the feasibility and measure the effectiveness of the forced evaporation, three cuboidal steel tubs were designed and implemented. The first control-tub was installed at the ground level to monitor natural evaporation. Similarly, the second and the third tub, models under investigation, were installed respectively at the ground level (equipped-tub 1) and out of the ground level (equipped-tub 2), and provided with special equipment to accelerate the evaporation process. The obtained results showed that the evaporation rate at the equipped-tubs was much accelerated with respect to the control-tub. It was accelerated five times in the winter period, where the evaporation rate was increased from a value of 0.37 mm/day to reach a value of 1.50 mm/day. In the summer period, the evaporation rate was accelerated more than three times and it increased from a value of 3.06 mm/day to reach a value of 10.25 mm/day. Overall, the optimized evaporation technique can be applied effectively either under electric or solar energy supply, and will accelerate the evaporation rate from three to five times whatever the season temperature. Copyright © 2016. Published by Elsevier Ltd.

L-Nitroargininium picrate

NASA Astrophysics Data System (ADS)

Apreyan, R. A.; Fleck, M.; Atanesyan, A. K.; Sukiasyan, R. P.; Petrosyan, A. M.

2015-12-01

L-Nitroargininium picrate has been obtained from an aqueous solution containing equimolar quantities of L-nitroarginine and picric acid by slow evaporation. Single crystal was grown by evaporation method. Crystal structure was determined at room temperature. The salt crystallizes in monoclinic crystal system (space group P21). Vibrational spectra and thermal properties were studied. Second harmonic generation efficiency measured by powder method is found to be four times higher than in L-nitroarginine, which in turn is ten times more efficient than KDP (KH2PO4).

Microfabricated valveless devices for thermal bioreactions based on diffusion-limited evaporation.

PubMed

Wang, Fang; Yang, Ming; Burns, Mark A

2008-01-01

Microfluidic devices that reduce evaporative loss during thermal bioreactions such as PCR without microvalves have been developed by relying on the principle of diffusion-limited evaporation. Both theoretical and experimental results demonstrate that the sample evaporative loss can be reduced by more than 20 times using long narrow diffusion channels on both sides of the reaction region. In order to further suppress the evaporation, the driving force for liquid evaporation is reduced by two additional techniques: decreasing the interfacial temperature using thermal isolation and reducing the vapor concentration gradient by replenishing water vapor in the diffusion channels. Both thermal isolation and vapor replenishment techniques can limit the sample evaporative loss to approximately 1% of the reaction content.

Evaluating evaporation from field crops using airborne radiometry and ground-based meteorological data

USGS Publications Warehouse

Jackson, R. D.; Moran, M.S.; Gay, L.W.; Raymond, L.H.

1987-01-01

Airborne measurements of reflected solar and emitted thermal radiation were combined with ground-based measurements of incoming solar radiation, air temperature, windspeed, and vapor pressure to calculate instantaneous evaporation (LE) rates using a form of the Penman equation. Estimates of evaporation over cotton, wheat, and alfalfa fields were obtained on 5 days during a one-year period. A Bowen ratio apparatus, employed simultaneously, provided ground-based measurements of evaporation. Comparison of the airborne and ground techniques showed good agreement, with the greatest difference being about 12% for the instantaneous values. Estimates of daily (24 h) evaporation were made from the instantaneous data. On three of the five days, the difference between the two techniques was less than 8%, with the greatest difference being 25%. The results demonstrate that airborne remote sensing techniques can be used to obtain spatially distributed values of evaporation over agricultural fields. ?? 1987 Springer-Verlag.

Humidity-insensitive water evaporation from molecular complex fluids.

PubMed

Salmon, Jean-Baptiste; Doumenc, Frédéric; Guerrier, Béatrice

2017-09-01

We investigated theoretically water evaporation from concentrated supramolecular mixtures, such as solutions of polymers or amphiphilic molecules, using numerical resolutions of a one-dimensional model based on mass transport equations. Solvent evaporation leads to the formation of a concentrated solute layer at the drying interface, which slows down evaporation in a long-time-scale regime. In this regime, often referred to as the falling rate period, evaporation is dominated by diffusive mass transport within the solution, as already known. However, we demonstrate that, in this regime, the rate of evaporation does not also depend on the ambient humidity for many molecular complex fluids. Using analytical solutions in some limiting cases, we first demonstrate that a sharp decrease of the water chemical activity at high solute concentration leads to evaporation rates which depend weakly on the humidity, as the solute concentration at the drying interface slightly depends on the humidity. However, we also show that a strong decrease of the mutual diffusion coefficient of the solution enhances considerably this effect, leading to nearly independent evaporation rates over a wide range of humidity. The decrease of the mutual diffusion coefficient indeed induces strong concentration gradients at the drying interface, which shield the concentration profiles from humidity variations, except in a very thin region close to the drying interface.

Realization of PbS thin films by reactive evaporation technique for possible opto-electronic applications

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

A, Abhilash, E-mail: abhiltp@cusat.ac.in; Nair, Aparna S.; S, Rajasree

2015-06-24

Stoichiometric Lead sulphide (PbS) thin films were successfully prepared on glass substrates by reactive evaporation technique. Elemental evaporation of lead and sulphur taken in different sources onto substrates held at temperature of 400±5K employed in the present study. The structural as well as compositional studies compromises compound formation. Electrical transport properties and optical co-efficient were evaluated from appropriate characterization techniques.

Streamer Evaporation

NASA Technical Reports Server (NTRS)

Suess, Steven T.; Wang, A. H.; Wu, Shi T.; Nerney, S.

1998-01-01

Evaporation is the consequence of slow plasma heating near the tops of streamers where the plasma is only weakly contained by the magnetic field. The form it takes is the slow opening of field lines at the top of the streamer and transient formation of new solar wind. It was discovered in polytropic model calculations, where due to the absence of other energy loss mechanisms in magnetostatic streamers, its ultimate endpoint is the complete evaporation of the streamer. This takes, for plausible heating rates, weeks to months in these models. Of course streamers do not behave this way, for more than one reason. One is that there are losses due to thermal conduction to the base of the streamer and radiation from the transition region. Another is that streamer heating must have a characteristic time constant and depend on the ambient physical conditions. We use our global Magnetohydrodynamics (MHD) model with thermal conduction to examine a few examples of the effect of changing the heating scale height and of making ad hoc choices for how the heating depends on ambient conditions. At the same time, we apply and extend the analytic model of streamers, which showed that streamers will be unable to contain plasma for temperatures near the cusp greater than about 2xl0(exp 6) K. Slow solar wind is observed to come from streamers through transient releases. A scenario for this that is consistent with the above physical process is that heating increases the near-cusp temperature until field lines there are forced open. The subsequent evacuation of the flux tubes by the newly forming slow wind decreases the temperature and heating until the flux tubes are able to reclose. Then, over a longer time scale, heating begins to again refill the flux tubes with plasma and increase the temperature until the cycle repeats itself. The calculations we report here are first steps towards quantitative evaluation of this scenario.

Study on optical properties of L-valine doped ADP crystal

NASA Astrophysics Data System (ADS)

Shaikh, R. N.; Anis, Mohd.; Shirsat, M. D.; Hussaini, S. S.

2015-02-01

Single crystal of L-valine doped ammonium dihydrogen phosphate has been grown by slow evaporation method at room temperature. The crystalline nature of the grown crystal was confirmed using powder X-ray diffraction technique. The different functional groups of the grown crystal were identified using Fourier transform infrared analysis. The UV-visible studies were employed to examine the high optical transparency and influential optical constants for tailoring materials suitability for optoelectronics applications. The cutoff wavelength of the title crystal was found to be 280 nm with wide optical band gap of 4.7 eV. The dielectric measurements were carried to determine the dielectric constant and dielectric loss at room temperature. The grown crystal has been characterized by thermogravimetric analysis. The second harmonic generation efficiency of the grown crystal was determined by the classical Kurtz powder technique and it is found to be 1.92 times that of potassium dihydrogen phosphate. The grown crystal was identified as third order nonlinear optical material employing Z-scan technique using He-Ne laser operating at 632.8 nm.

The growth and perfection of β-cyclotetramethylene-tetranitramine (HMX) studied by laboratory and synchrotron X-ray topography

NASA Astrophysics Data System (ADS)

Gallagher, H. G.; Sherwood, J. N.; Vrcelj, R. M.

2017-10-01

An examination has been made of the defect structure of crystals of the energetic material β-cyclotetramethylene-tetranitramine (HMX) using both Laboratory (Lang method) and Synchrotron (Bragg Reflection and Laue method) techniques. The results of the three methods are compared with particular attention to the influence of potential radiation damage caused to the samples by the latter, more energetic, technique. The comparison shows that both techniques can be confidently used to evaluate the defect structures yielding closely similar results. The results show that, even under the relatively casual preparative methods used (slow evaporation of unstirred solutions at constant temperature), HMX crystals of high perfection can be produced. The crystals show well defined bulk defect structures characteristic of organic materials in general: growth dislocations, twins, growth sector boundaries, growth banding and solvent inclusions. The distribution of the defects in specific samples is correlated with the morphological variation of the grown crystals. The results show promise for the further evaluation and characterisation of the structure and properties of dislocations and other defects and their involvement in mechanical and energetic processes in this material.

Quantitative comparison of organic photovoltaic bulk heterojunction photostability under laser illumination

DOE PAGES

Lesoine, Michael D.; Bobbitt, Jonathan M.; Carr, John A.; ...

2014-11-20

The photostability of bulk heterojunction organic photovoltaic films containing a polymer donor and a fullerene-derivative acceptor was examined using resonance Raman spectroscopy and controlled laser power densities. The polymer donors were poly(3-hexylthiophene-2,5-diyl) (P3HT), poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl] (PCDTBT), or poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}) (PTB7). Four sample preparation methods were studied: (i) thin or (ii) thick films with fast solvent evaporation under nitrogen, (iii) thick films with slow solvent evaporation under nitrogen, and (iv) thin films dried under nitrogen followed by thermal annealing. Polymer order was assessed by monitoring a Raman peak’s full width at half-maximum and location as a function of illumination time and laser powermore » densities from 2.5 × 10 3 to 2.5 × 10 5 W cm –2. Resonance Raman spectroscopy measurements show that before prolonged illumination, PCDTBT and PTB7 have the same initial order for all preparation conditions, while P3HT order improves with slow solvent drying or thermal annealing. All films exhibited changes to bulk heterojunction structure with 2.5 × 10 5 Wcm –2 laser illumination as measured by resonance Raman spectroscopy, and atomic force microscopy images show evidence of sample heating that affects the polymer over an area greater than the illumination profile. Furthermore, photostability data are important for proper characterization by techniques involving illumination and the development of devices suitable for real-world applications.« less

Synthesis, structural, thermal and Hirshfeld surface analysis of novel [1,2,4]triazolo[3,4-b][1,3,4] thiadiazine carrying 1,4-benzothiazine-3-one moiety

NASA Astrophysics Data System (ADS)

Shruthi, C.; Ravindrachary, V.; Guruswamy, B.; Lokanath, N. K.; Kumara, Karthik; Goveas, Janet

2018-05-01

Needle shaped single crystal of the title compound was grown by slow evaporation solution growth technique using ethanol as solvent. The grown single crystal was characterized using FT-IR, Single crystal XRD and Thermal analysis. The FT-IR spectrum confirms the molecular structure and identifies the different functional groups present in the compound. Single crystal XRD study reveals that the crystallized compound belongs to the monoclinic crystal system with P21/c space group and the corresponding cell parameters were identified. The thermal stability of the material was determined using both TGA and DTA analysis. The intermolecular interaction of each individual atom in the crystal lattice was estimated using Hirshfeld surface and finger print analysis.

Studies on the growth aspects, structural, thermal, dielectric and third order nonlinear optical properties of solution grown 4-methylpyridinium p-nitrophenolate single crystal

NASA Astrophysics Data System (ADS)

Devi, S. Reena; Kalaiyarasi, S.; Zahid, I. MD.; Kumar, R. Mohan

2016-11-01

An ionic organic optical crystal of 4-methylpyridinium p-nitrophenolate was grown from methanol by slow evaporation method at ambient temperature. Powder and single crystal X-ray diffraction studies revealed the crystal system and its crystalline perfection. The rocking curve recorded from HRXRD study confirmed the crystal quality. FTIR spectral analysis confirmed the functional groups present in the title compound. UV-visible spectral study revealed the optical window and band gap of grown crystal. The thermal, electrical and surface laser damage threshold properties of harvested crystal were examined by using TGA/DTA, LCR/Impedance Analyzer and Nd:YAG laser system respectively. The third order nonlinear optical property of grown crystal was elucidated by Z-scan technique.

Structural, chemical and physical properties of pure and La3+ doped L-Threonine acetate crystals

NASA Astrophysics Data System (ADS)

Senthamizhan, A.; Sambathkumar, K.; Nithiyanantham, S.; Venkatachalapathy, M.; Rajkamal, N.

2017-12-01

The pure and La3+ doped L- Threonine crystals can be grown by slow evaporation techniques. The crystal structure were examined through X-Ray diffraction (XRD) analysis, confirmed the P212121 system. The quantitative nature of dopant can be analyzed with Inductively Coupled Plasma (ICP) study. The Fourier Transform Infra-Red (FTIR) and Fourier Transform (FT- Raman) investigations yields the possible stretching/bonding with their functional groups and the qualitative/quantitative nature of both crystals is analyzed. The optical behavior of crystals can be studied through Ultra Violet (UV) - Visible spectrometer. The mechanical, thermal and decomposition studies can be carried out through Vickers hardness test, Thermo Gravometric Analysis (TGA) and Differential Thermal Analysis (DTA). The Non Linear Optical (NLO) properties are found more than Potassium Phosphate (KDP) through Kurtz powders technique. The dielectric and optical absorption studies for both pure and L-doped crystals were studied and interpreted all the properties. The La3+ dopant increases the properties are investigated.

Studies on synthesis, growth, structural, thermal, linear and nonlinear optical properties of organic picolinium maleate single crystals.

PubMed

Pandi, P; Peramaiyan, G; Sudhahar, S; Chakkaravarthi, G; Mohan Kumar, R; Bhagavannarayana, G; Jayavel, R

2012-12-01

Picolinium maleate (PM), an organic material has been synthesised and single crystals were grown by slow evaporation technique. The structure of the grown crystal was elucidated by using single crystal X-ray diffraction analysis. PM crystal belongs to the monoclinic crystallographic system with space group P2(1)/c. The crystalline perfection of the grown crystals was analyzed by high-resolution X-ray diffraction rocking curve measurements. The presence of functional groups in PM was identified by FTIR and FT-NMR spectral analyses. Thermal behaviour and stability of picolinium maleate were studied by TGA/DTA analyses. UV-Vis spectral studies reveal that PM crystals are transparent in the wavelength region 327-1100 nm. The laser damage threshold value of PM crystal was found to be 4.3 GW/cm(2) using Nd:YAG laser. The Kurtz and Perry powder second harmonic generation technique confirms the nonlinear optical property of the grown crystal. Copyright © 2012 Elsevier B.V. All rights reserved.

Optical, mechanical and thermal behaviors of Nitrilotriacetic acid single crystal

NASA Astrophysics Data System (ADS)

Deepa, B.; Philominathan, P.

2017-11-01

An organic nonlinear single crystal of Nitrilotriacetic acid (NTAA) was grown for the first time by employing a simple slow evaporation technique. Single crystal X-ray diffraction (XRD) analysis reveals that the grown crystal belongs to the monoclinic system with noncentrosymmetric space group CC. Fourier transform infrared (FTIR) spectral study ascertains the presence of functional groups in NTAA. The molecular structure of the grown crystal was confirmed by Nuclear Magnetic Resonance (NMR) spectral analysis. The optical parameters such as transmittance, absorption coefficient and band gap were calculated from UV-Visible and fluorescence studies. Dielectric measurements were carried out for different frequency and temperature. The mechanical strength of the grown crystal was measured using Vickers microhardness test. The high thermal stability and the melting point of the grown crystal were also estimated using thermogravimetric (TGA) and differential thermal analyses (DTA). The confirmation of the grown crystals belonging to nonlinear optical crystals was performed by Kurtz-Perry technique and found as suitable candidate for optoelectronics applications.

Synthesis, growth, structure and nonlinear optical properties of a semiorganic 2-carboxy pyridinium dihydrogen phosphate single crystal

NASA Astrophysics Data System (ADS)

Nagapandiselvi, P.; Baby, C.; Gopalakrishnan, R.

2015-09-01

A new semiorganic compound namely, 2-carboxy pyridinium dihydrogen phosphate (2CPDP) was synthesised and grown as single crystals by slow evaporation solution growth technique. Single crystal XRD showed that 2CPDP belongs to monoclinic crystal system with space group P21/n. The molecular structure was further confirmed by modern spectroscopic techniques like FT-NMR (1H, 13C &31P), FT-IR, UV-Vis-NIR and Fluorescence. The UV-Vis-NIR analysis revealed suitability of the crystal for nonlinear optical applications. The photo active nature of the material is established from fluorescence studies. TG-DSC analysis showed that 2CPDP was thermally stable up to 170 °C. The dependence of dielectric properties on frequency and temperature were also studied. Nonlinear optical absorption determined from open aperture Z-Scan analysis by employing picosecond Nd-YAG laser, revealed that 2CPDP can serve as a promising candidate for optical limiting applications.

Formation of 2D and 3D superlattices of silver nanoparticles inside an emulsion droplet

NASA Astrophysics Data System (ADS)

Hussain Shaik, Aabid; Srinivasa Reddy, D.

2017-03-01

This work is aimed at the formation of 2D and 3D superlattices (SL) of silver nanoparticles inside an emulsion droplet. The monodisperse nanoparticles required for SL formation were prepared by a digestive ripening technique. Digestive ripening is a post processing technique where polydisperse colloids are refluxed with excess surface-active ligands to prepare a monodisperse colloid. More uniform silver nanoparticles (~3.6  ±  0.5 nm) were formed by slow evaporation of organosols on a carbon-coated copper grid. The best 3D silver superlattices have been formed using an oil in water (o/w) emulsion method by aging the monodisperse particles in a confined environment like o/w emulsion at different temperatures ranging from 5 °C-4 °C. The kinetics of the formation of superlattices inside an emulsion droplet were investigated by controlling various parameters. The kinetics were found to be dependent on the emulsion aging period (30 d) and storage temperature of the emulsion (-4 °C).

Daily pan evaporation modelling using a neuro-fuzzy computing technique

NASA Astrophysics Data System (ADS)

Kişi, Özgür

2006-10-01

SummaryEvaporation, as a major component of the hydrologic cycle, is important in water resources development and management. This paper investigates the abilities of neuro-fuzzy (NF) technique to improve the accuracy of daily evaporation estimation. Five different NF models comprising various combinations of daily climatic variables, that is, air temperature, solar radiation, wind speed, pressure and humidity are developed to evaluate degree of effect of each of these variables on evaporation. A comparison is made between the estimates provided by the NF model and the artificial neural networks (ANNs). The Stephens-Stewart (SS) method is also considered for the comparison. Various statistic measures are used to evaluate the performance of the models. Based on the comparisons, it was found that the NF computing technique could be employed successfully in modelling evaporation process from the available climatic data. The ANN also found to perform better than the SS method.

Influence of three different concentration techniques on evaporation rate, color and phenolics content of blueberry juice.

PubMed

Elik, Aysel; Yanık, Derya Koçak; Maskan, Medeni; Göğüş, Fahrettin

2016-05-01

The present study was undertaken to assess the effects of three different concentration processes open-pan, rotary vacuum evaporator and microwave heating on evaporation rate, the color and phenolics content of blueberry juice. Kinetics model study for changes in soluble solids content (°Brix), color parameters and phenolics content during evaporation was also performed. The final juice concentration of 65° Brix was achieved in 12, 15, 45 and 77 min, for microwave at 250 and 200 W, rotary vacuum and open-pan evaporation processes, respectively. Color changes associated with heat treatment were monitored using Hunter colorimeter (L*, a* and b*). All Hunter color parameters decreased with time and dependently studied concentration techniques caused color degradation. It was observed that the severity of color loss was higher in open-pan technique than the others. Evaporation also affected total phenolics content in blueberry juice. Total phenolics loss during concentration was highest in open-pan technique (36.54 %) and lowest in microwave heating at 200 W (34.20 %). So, the use of microwave technique could be advantageous in food industry because of production of blueberry juice concentrate with a better quality and short time of operation. A first-order kinetics model was applied to modeling changes in soluble solids content. A zero-order kinetics model was used to modeling changes in color parameters and phenolics content.

Inventory Control.

ERIC Educational Resources Information Center

Sievers, Dennis, Ed.

1986-01-01

Describes apparatus for use in high school chemistry instruction. Provides instructions and lists of materials needed for building a homemade sand bath for use in experiments that demonstrate the slow evaporation of a solvent. Plans for the construction of a low-cost conductivity apparatus are also included. (TW)

Moving-Boundary Problems Associated with Lyopreservation

NASA Astrophysics Data System (ADS)

Gruber, Christopher Andrew

The work presented in this Dissertation is motivated by research into the preservation of biological specimens by way of vitrification, a technique known as lyopreservation. The operative principle behind lyopreservation is that a glassy material forms as a solution of sugar and water is desiccated. The microstructure of this glass impedes transport within the material, thereby slowing metabolism and effectively halting the aging processes in a biospecimen. This Dissertation is divided into two segments. The first concerns the nature of diffusive transport within a glassy state. Experimental studies suggest that diffusion within a glass is anomalously slow. Scaled Brownian motion (SBM) is proposed as a mathematical model which captures the qualitative features of anomalously slow diffusion while minimizing computational expense. This model is applied to several moving-boundary problems and the results are compared to a more well-established model, fractional anomalous diffusion (FAD). The virtues of SBM are based on the model's relative mathematical simplicity: the governing equation under FAD dynamics involves a fractional derivative operator, which precludes the use of analytical methods in almost all circumstances and also entails great computational expense. In some geometries, SBM allows similarity solutions, though computational methods are generally required. The use of SBM as an approximation to FAD when a system is "nearly classical'' is also explored. The second portion of this Dissertation concerns spin-drying, which is an experimental approach to biopreservation in a laboratory setting. A biospecimen is adhered to a glass wafer and this substrate is covered with sugar solution and rapidly spun on a turntable while water is evaporated from the film surface. The mathematical model for the spin-drying process includes diffusion, viscous fluid flow, and evaporation, among other contributions to the dynamics. Lubrication theory is applied to the model and an expansion in orthogonal polynomials is applied. The resulting system of equations is solved computationally. The influence of various experimental parameters upon the system dynamics is investigated, particularly the role of the spin rate. A convergence study of the solution verifies that the polynomial expansion method yields accurate results.

Piezoelectric Polymer Tactile Sensor Arrays for Robotics.

DTIC Science & Technology

1987-12-01

response to slow and fast stimuli (Dario and others, 1984:2). The touch receptors relate tactile information through a variety of tactile sensory...flexure. The only occurrence when an evaporated electrode broke (and became intermit - tently open circuited) was during the measurement of the PPTSA *4

Thermal, dielectric studies on pure and amino acid ( L-glutamic acid, L-histidine, L-valine) doped KDP single crystals

NASA Astrophysics Data System (ADS)

Kumaresan, P.; Moorthy Babu, S.; Anbarasan, P. M.

2008-05-01

Amino acids ( L-glutamic acid, L-histidine, L-valine) doped potassium dihydrogen phospate crystals are grown by solution growth technique. Slow cooling as well as slow evaporation methods were employed to grow these crystals. The concentration of dopants in the mother solution was varied from 0.1 mol% to 10 mol%. The solubility data for all dopants concentration were determined. There is variation in pH value and hence, there is habit modification of the grown crystals were characterized with UV-VIS, FT-IR studies, SHG trace elements and dielectric studies reveal slight distortion of lattice parameter for the heavily doped KDP crystals. UV-Visible spectra confirm the improvement in the transparency of these crystals on doping metal ions. FT-IR spectra reveal strong absorption band between 1400 and 1600 cm -1 for metal ion doped crystals. TGA-DTA studies reveal good thermal stability. The dopants increase the hardness value of the material and it also depends on the concentration of the dopants. Amino acids doping improved the NLO properties. The detailed results on the spectral parameters, habit modifications and constant values will be presented.

Gold and Iron Oxide Nanoparticle-Based Ethylcellulose Nanocapsules for Cisplatin Drug Delivery

PubMed Central

Sathish Kumar, Kannaiyan; Jaikumar, Vasudevan

2011-01-01

The present study is aimed at the overall improvement in the efficacy, reduced toxicity and enhancement of therapeutic index of cisplatin. Nanocapsules of cisplatin containing ethylcellulose have been prepared using solvent evaporation technique under ambient conditions. The prepared nanocapsules were used for controlled drug release of anticancer agents with gold and iron oxide nanoparticles. The drug-entrapped nanocapsules were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fourier transform infrared (FTIR) studies indicated the absence of chemical interactions between the drug, polymer and metal nanoparticles. The drug loaded nanoparticles are spherical in shape and had average diameter in the range of 100-300 nm. Drug release study showed that the acidic media provided a faster release than the phosphate buffer media. These findings were also compared statistically through calculating mean, standard deviation and coefficient of variation for various polymer nanocapsules. However, the drug release for gold nanoparticles/anticancer drug (Au-cis) incorporated ethylcellulose nanocapsules was controlled and slow compared to iron oxide nanoparticles-cisplatin incorporated ethylcellulose nanocapsules. Hence, gold nanoparticles act as good trapping agents which slow down the rate of drug release from nanocapsules. PMID:24250373

Method for controlling protein crystallization

NASA Technical Reports Server (NTRS)

Noever, David A. (Inventor)

1993-01-01

A method and apparatus for controlling the crystallization of protein by solvent evaporation including placing a drop of protein solution between and in contact with a pair of parallel plates and driving one of the plates toward and away from the other plate in a controlled manner to adjust the spacing between the plates is presented. The drop of solution forms a liquid cylinder having a height dependent upon the plate spacing thereby effecting the surface area available for solvent evaporation. When the spacing is close, evaporation is slow. Evaporation is increased by increasing the spacing between the plates until the breaking point of the liquid cylinder. One plate is mounted upon a fixed post while the other plate is carried by a receptacle movable relative to the post and driven by a belt driven screw drive. The temperature and humidity of the drop of protein solution are controlled by sealing the drop within the receptacle and mounting a heater and dessicant within the receptacle.

Nanoparticle agglomeration in an evaporating levitated droplet for different acoustic amplitudes

NASA Astrophysics Data System (ADS)

Tijerino, Erick; Basu, Saptarshi; Kumar, Ranganathan

2013-01-01

Radiatively heated levitated functional droplets with nanosilica suspensions exhibit three distinct stages namely pure evaporation, agglomeration, and finally structure formation. The temporal history of the droplet surface temperature shows two inflection points. One inflection point corresponds to a local maximum and demarcates the end of transient heating of the droplet and domination of vaporization. The second inflection point is a local minimum and indicates slowing down of the evaporation rate due to surface accumulation of nanoparticles. Morphology and final precipitation structures of levitated droplets are due to competing mechanisms of particle agglomeration, evaporation, and shape deformation. In this work, we provide a detailed analysis for each process and propose two important timescales for evaporation and agglomeration that determine the final diameter of the structure formed. It is seen that both agglomeration and evaporation timescales are similar functions of acoustic amplitude (sound pressure level), droplet size, viscosity, and density. However, we show that while the agglomeration timescale decreases with initial particle concentration, the evaporation timescale shows the opposite trend. The final normalized diameter can be shown to be dependent solely on the ratio of agglomeration to evaporation timescales for all concentrations and acoustic amplitudes. The structures also exhibit various aspect ratios (bowls, rings, spheroids) which depend on the ratio of the deformation timescale (tdef) and the agglomeration timescale (tg). For tdef

[Measurement and estimation methods and research progress of snow evaporation in forests].

PubMed

Li, Hui-Dong; Guan, De-Xin; Jin, Chang-Jie; Wang, An-Zhi; Yuan, Feng-Hui; Wu, Jia-Bing

2013-12-01

Accurate measurement and estimation of snow evaporation (sublimation) in forests is one of the important issues to the understanding of snow surface energy and water balance, and it is also an essential part of regional hydrological and climate models. This paper summarized the measurement and estimation methods of snow evaporation in forests, and made a comprehensive applicability evaluation, including mass-balance methods (snow water equivalent method, comparative measurements of snowfall and through-snowfall, snow evaporation pan, lysimeter, weighing of cut tree, weighing interception on crown, and gamma-ray attenuation technique) and micrometeorological methods (Bowen-ratio energy-balance method, Penman combination equation, aerodynamics method, surface temperature technique and eddy covariance method). Also this paper reviewed the progress of snow evaporation in different forests and its influencal factors. At last, combining the deficiency of past research, an outlook for snow evaporation rearch in forests was presented, hoping to provide a reference for related research in the future.

Streamer Evaporation

NASA Technical Reports Server (NTRS)

Suess, S. T.; Wang, A.-H.; Wu, S. T.; Nerney, S. F.

1998-01-01

Evaporation is the consequence of heating near the top of streamers in ideal Magnetohydrodynamics (MHD) models, where the plasma is weakly contained by the magnetic field. Heating causes slow opening of field lines and release of new solar wind. It was discovered in simulations and, due to the absence of loss mechanisms, the ultimate end point is the complete evaporation of the streamer. Of course streamers do not behave in this way because there are losses by thermal conduction and radiation. Physically, heating is also expected to depend on ambient conditions. We use our global MHD model with thermal conduction to examine the effect of changing the heating scale height. We also apply and extend an analytic model of streamers developed by Pneuman (1968) to show that steady streamers are unable to contain plasma for temperatures near the cusp greater than approximately 2 x 10(exp 6) K.

The Crystal and Molecular Structure of Dianhydrogossypol

USDA-ARS?s Scientific Manuscript database

Dianhydrogossypol (4,4'-dihydroxy-5,5'-diisopropyl-7,7'-dimethyl-bis(3H-naphtho[1,8-bc]furan-3-one)) was made by refluxing gossypol in m-xylene. Proton NMR confirmed that complete conversion was achieved over several hours. Single crystals were obtained by slow evaporation of the product from dichl...

Selecting the spin crossover profile with controlled crystallization of mononuclear Fe(iii) polymorphs.

PubMed

Vicente, Ana I; Ferreira, Liliana P; Carvalho, Maria de Deus; Rodrigues, Vítor H N; Dîrtu, Marinela M; Garcia, Yann; Calhorda, Maria José; Martinho, Paulo N

2018-05-08

Two polymorphic species of the [Fe(5-Br-salEen)2]ClO4 compound were obtained, each of them being selectively recovered after evaporation of the solvent at a controlled rate. While polymorph 1a is formed during slow evaporation, fast evaporation favors polymorph 1b. The importance of the evaporation rate was recognized after detailed studies of the reaction temperature, solvent evaporation rate and crystallization temperature effects. The complex in the new polymorphic form 1a showed an abrupt spin crossover at 172 K with a small 1 K hysteresis window and over a narrow 10 K range. 57Fe Mössbauer spectroscopy and differential scanning calorimetry, complemented by X-ray studies for both the high-spin and low-spin forms, were used to further characterize the new polymorphic phase 1a. Both polymorphs are based on the same Fe(iii) complex cation hydrogen bonded to the perchlorate anion. These units are loosely bound in the crystals via weak interactions. In the new polymorph 1a, the hydrogen bonds are stronger, while the weak hydrogen and halogen bonds, as well as π-π stacking, create a cooperative network, not present in 1b, responsible for the spin transition profile.

Leidenfrost Phenomenon-assisted Thermal Desorption (LPTD) and Its Application to Open Ion Sources at Atmospheric Pressure Mass Spectrometry

NASA Astrophysics Data System (ADS)

Saha, Subhrakanti; Chen, Lee Chuin; Mandal, Mridul Kanti; Hiraoka, Kenzo

2013-03-01

This work describes the development and application of a new thermal desorption technique that makes use of the Leidenfrost phenomenon in open ion sources at atmospheric pressure for direct mass spectrometric detection of ultratrace levels of illicit, therapeutic, and stimulant drugs, toxicants, and peptides (molecular weight above 1 kDa) in their unaltered state from complex real world samples without or with minor sample pretreatment. A low temperature dielectric barrier discharge ion source was used throughout the experiments and the analytical figures of merit of this technique were investigated. Further, this desorption technique coupled with other ionization sources such as electrospray ionization (ESI) and dc corona discharge atmospheric pressure chemical ionization (APCI) in open atmosphere was also investigated. The use of the high-resolution `Exactive Orbitrap' mass spectrometer provided unambiguous identification of trace levels of the targeted compounds from complex mixtures and background noise; the limits of detection for various small organic molecules and peptides treated with this technique were at the level of parts per trillion and 10-9 M, respectively. The high sensitivity of the present technique is attributed to the spontaneous enrichment of analyte molecules during the slow evaporation of the solvent, as well as to the sequential desorption of molecules from complex mixtures based on their volatilities. This newly developed desorption technique is simple and fast, while molecular ions are observed as the major ions.

Synthesis, crystal growth, optical, thermal, and mechanical properties of a nonlinear optical single crystal: ammonium sulfate hydrogen sulphamate (ASHS)

NASA Astrophysics Data System (ADS)

Sudhakar, K.; Nandhini, S.; Muniyappan, S.; Arumanayagam, T.; Vivek, P.; Murugakoothan, P.

2018-04-01

Ammonium sulfate hydrogen sulphamate (ASHS), an inorganic nonlinear optical crystal, was grown from the aqueous solution by slow evaporation solution growth technique. The single-crystal XRD confirms that the grown single crystal belongs to the orthorhombic system with the space group of Pna21. Powder XRD confirms the crystalline nature and the diffraction planes were indexed. Crystalline perfection of grown crystal was analysed by high-resolution X-ray diffraction rocking curve technique. UV-Vis-NIR studies revealed that ASHS crystal has optical transparency 65% and lower cut-off wavelength at 218 nm. The violet light emission of the crystal was identified by photoluminescence studies. The particle size-dependent second-harmonic generation efficiency for ASHS crystal was evaluated by Kurtz-Perry powder technique using Nd:YAG laser which established the existence of phase matching. Surface laser damage threshold value was evaluated using Nd:YAG laser. Optical homogeneity of the crystal was evaluated using modified channel spectrum method through birefringence study. Thermal analysis reveals that ASHS crystal is stable up to 213 °C. The mechanical behaviour of the ASHS crystal was analysed using Vickers microhardness study.

Crystal growth and DFT insight on sodium para-nitrophenolate para-nitrophenol dihydrate single crystal for NLO applications

NASA Astrophysics Data System (ADS)

Selvakumar, S.; Boobalan, Maria Susai; Anthuvan Babu, S.; Ramalingam, S.; Leo Rajesh, A.

2016-12-01

Single crystals of sodium para-nitrophenolate para-nitrophenol dihydrate (SPPD) were grown by slow evaporation technique and its structure has been studied by FT-IR, FT-Raman and single crystal X-ray diffraction techniques. The optical and electrical properties were characterized by UV-Vis spectrum, and dielectric studies respectively. SPPD was thermally stable up to 128 °C as determined by TG-DTA curves. Using the Kurtz-Perry powder method, the second-harmonic generation efficiency was found to be five times to that of KDP. Third-order nonlinear response was studied using Z-scan technique with a He-Ne laser (632.8 nm) and NLO parameters such as intensity dependent refractive index, nonlinear absorption coefficient and third-order susceptibility were also estimated. The molecular geometry from X-ray experiment in the ground state has been compared using density functional theory (DFT) with appropriate basis set. The first-order hyperpolarizability also calculated using DFT approaches. Stability of the molecule arising from hyperconjugative interactions leading to its nonlinear optical activity and charge delocalization were analyzed using natural bond orbital technique. HOMO-LUMO energy gap value suggests the possibility of charge transfer within the molecule. Based on optimized ground state geometries, Natural bond orbital (NBO) analysis was performed to study donor-acceptor interactions.

Purification of Drug Loaded PLGA Nanoparticles Prepared by Emulsification Solvent Evaporation Using Stirred Cell Ultrafiltration Technique.

PubMed

Paswan, Suresh K; Saini, T R

2017-12-01

The emulsifiers in an exceedingly higher level are used in the preparation of drug loaded polymeric nanoparticles prepared by emulsification solvent evaporation method. This creates great problem to the formulator due to their serious toxicities when it is to be administered by parenteral route. The final product is therefore required to be freed from the used surfactants by the conventional purification techniques which is a cumbersome job. The solvent resistant stirred cell ultrafiltration unit (Millipore) was used in this study using polyethersulfone ultrafiltration membrane (Biomax®) having pore size of NMWL 300 KDa as the membrane filter. The purification efficiency of this technique was compared with the conventional centrifugation technique. The flow rate of ultrafiltration was optimized for removal of surfactant (polyvinyl alcohol) impurities to the acceptable levels in 1-3.5 h from the nanoparticle dispersion of tamoxifen prepared by emulsification solvent evaporation method. The present investigations demonstrate the application of solvent resistant stirred cell ultrafiltration technique for removal of toxic impurities of surfactant (PVA) from the polymeric drug nanoparticles (tamoxifen) prepared by emulsification solvent evaporation method. This technique offers added benefit of producing more concentrated nanoparticles dispersion without causing significant particle size growth which is observed in other purification techniques, e.g., centrifugation and ultracentrifugation.

Simultaneous measurement of monocomponent droplet temperature/refractive index, size and evaporation rate with phase rainbow refractometry

NASA Astrophysics Data System (ADS)

Wu, Yingchun; Crua, Cyril; Li, Haipeng; Saengkaew, Sawitree; Mädler, Lutz; Wu, Xuecheng; Gréhan, Gérard

2018-07-01

The accurate measurements of droplet temperature, size and evaporation rate are of great importance to characterize the heat and mass transfer during evaporation/condensation processes. The nanoscale size change of a micron-sized droplet exactly describes its transient mass transfer, but is difficult to measure because it is smaller than the resolutions of current size measurement techniques. The Phase Rainbow Refractometry (PRR) technique is developed and applied to measure droplet temperature, size and transient size changes and thereafter evaporation rate simultaneously. The measurement principle of PRR is theoretically derived, and it reveals that the phase shift of the time-resolved ripple structures linearly depends on, and can directly yield, nano-scale size changes of droplets. The PRR technique is first verified through the simulation of rainbows of droplets with changing size, and results show that PRR can precisely measure droplet refractive index, absolute size, as well as size change with absolute and relative errors within several nanometers and 0.6%, respectively, and thus PRR permits accurate measurements of transient droplet evaporation rates. The evaporations of flowing single n-nonane droplet and mono-dispersed n-heptane droplet stream are investigated by two PRR systems with a high speed linear CCD and a low speed array CCD, respectively. Their transient evaporation rates are experimentally determined and quantitatively agree well with the theoretical values predicted by classical Maxwell and Stefan-Fuchs models. With the demonstration of evaporation rate measurement of monocomponent droplet in this work, PRR is an ideal tool for measurements of transient droplet evaporation/condensation processes, and can be extended to multicomponent droplets in a wide range of industrially-relevant applications.

Synthesis of calcium vanadate minerals and related compounds

USGS Publications Warehouse

Marvin, Richard F.

1956-01-01

Synthesis of natural vanadates shows that most of them are stable in an acid environment. Phase studies of a portion of the system CaO-V2O5-H2O indicate that calcium vanadates are an indicator of environmental pH conditions. Some minerals, such as pascoute, indicate rapid evaporation of vanadite solutions; other minerals, such as hewettite, show that slow evaporation took place. Cursory examination of systems K2O-UO2-(NO3)2-V2O5 and CaO-UO2(NO3)2-V2O5, both in aqueous solution, has yielded information on the relationships among carnotite, tyuyamunite, and rauvite.

Steady Method for the Analysis of Evaporation Dynamics.

PubMed

Günay, A Alperen; Sett, Soumyadip; Oh, Junho; Miljkovic, Nenad

2017-10-31

Droplet evaporation is an important phenomenon governing many man-made and natural processes. Characterizing the rate of evaporation with high accuracy has attracted the attention of numerous scientists over the past century. Traditionally, researchers have studied evaporation by observing the change in the droplet size in a given time interval. However, the transient nature coupled with the significant mass-transfer-governed gas dynamics occurring at the droplet three-phase contact line makes the classical method crude. Furthermore, the intricate balance played by the internal and external flows, evaporation kinetics, thermocapillarity, binary-mixture dynamics, curvature, and moving contact lines makes the decoupling of these processes impossible with classical transient methods. Here, we present a method to measure the rate of evaporation of spatially and temporally steady droplets. By utilizing a piezoelectric dispenser to feed microscale droplets (R ≈ 9 μm) to a larger evaporating droplet at a prescribed frequency, we can both create variable-sized droplets on any surface and study their evaporation rate by modulating the piezoelectric droplet addition frequency. Using our steady technique, we studied water evaporation of droplets having base radii ranging from 20 to 250 μm on surfaces of different functionalities (45° ≤ θ a,app ≤ 162°, where θ a,app is the apparent advancing contact angle). We benchmarked our technique with the classical unsteady method, showing an improvement of 140% in evaporation rate measurement accuracy. Our work not only characterizes the evaporation dynamics on functional surfaces but also provides an experimental platform to finally enable the decoupling of the complex physics governing the ubiquitous droplet evaporation process.

Synthesis, X-Ray diffraction, theoretical and anti-bacterial studies of bis-thiourea secondary amine

NASA Astrophysics Data System (ADS)

Fakhar, Imran; Hussien, Nasry Jassim; Sapari, Suhaila; Bloh, Anmar Hameed; Yusoff, Siti Fairus Mohd; Hasbullah, Siti Aishah; Yamin, Bohari Mohammad; Mutalib, Sahilah Abdul; Shihab, Mehdi Salih; Yousif, Emad

2018-05-01

N1,N4-Bis{(2-hydroxyethyl)(methyl)carbamothioyl}terephthalamide (1A) was synthesized by reacting terephthaloyl chloride and ammonium thiocyanate and the product was reacted with 2-Methyl amino ethanol to afford the final product. The product was characterized by Infra Red, Nuclear Magnetic Resonance and Electrospray Ionization mass Spectrometric techniques. The crystal was obtained by recrystallization from DMSO by slow evaporation technique. The X-ray studies reveal that (1A) is crystallized in monoclinic system with space group P 21/n, a = 6.9727(9), b = 17.649(2), c = 8.2629(11), α = 90, β = 112.329(4), γ = 90. Z = 2 and V = 940.6(2). In the crystal structure, the molecules are linked by O(1) … H(1) … S(1), and O(1) … H(1) … O(2) intermolecular H-bonds forming a 3-D network. In addition, the antibacterial activities against four different strains of bacteria and theoretical evaluation for the stable geometries for (1A) has been performed using semi-empirical calculations of PM3 method.

Synthesis, structural and spectral characterization of a novel NLO crystal N,N‧-diphenylguanidinium picrate: diacetone solvate

NASA Astrophysics Data System (ADS)

Shanmugavadivu, T.; Dhandapani, M.; Naveen, S.; Lokanath, N. K.

2017-09-01

An organic NLO active material N,N‧-diphenylguanidinium picrate: diacetone solvate (C13H14N3+. C6H2N3O7-. 2C3H6O) (DPGPD) was synthesized and single crystals were grown by slow evaporation-solution growth technique at room temperature. DPGPD crystallizes in monoclinic crystal system with noncentrosymmetric space group, Cc confirmed by single crystal X-ray diffraction analysis. The presence of various functional groups was identified from FT-IR spectral analysis and the proton transfer during the formation of compound was confirmed by NMR spectroscopic techniques. The thermal stability was investigated by TG/DTA analyses. Optical transmittance was measured by UV-Vis-NIR spectroscopy and band gap energy was calculated. Photoluminescence spectrum was used to explore its applicability towards laser diodes. Dielectric property of the material was ascertained at different temperatures and it is found that the grown crystal has higher dielectric constant in low frequencies. Photoconductivity study revealed that DPGPD exhibits positive photoconductivity. SHG property was found to be 0.6 times higher than that of KDP.

Crystal growth, structural, thermal and mechanical behavior of l-arginine 4-nitrophenolate 4-nitrophenol dihydrate (LAPP) single crystals.

PubMed

Mahadevan, M; Ramachandran, K; Anandan, P; Arivanandhan, M; Bhagavannarayana, G; Hayakawa, Y

2014-12-10

Single crystals of l-arginine 4-nitrophenolate 4-nitrophenol dihydrate (LAPP) have been grown successfully from the solution of l-arginine and 4-nitrophenol. Slow evaporation of solvent technique was adopted to grow the bulk single crystals. Single crystal X-ray diffraction analysis confirms the grown crystal has monoclinic crystal system with space group of P21. Powder X-ray diffraction analysis shows the good crystalline nature. The crystalline perfection of the grown single crystals was analyzed by HRXRD by employing a multicrystal X-ray diffractometer. The functional groups were identified from proton NMR spectroscopic analysis. Linear and nonlinear optical properties were determined by UV-Vis spectrophotometer and Kurtz powder technique respectively. It is found that the grown crystal has no absorption in the green wavelength region and the SHG efficiency was found to be 2.66 times that of the standard KDP. The Thermal stability of the crystal was found by obtaining TG/DTA curve. The mechanical behavior of the grown crystal has been studied by Vicker's microhardness method. Copyright © 2014 Elsevier B.V. All rights reserved.

Structural, thermal and optical characterization of an organic NLO material--benzaldehyde thiosemicarbazone monohydrate single crystals.

PubMed

Santhakumari, R; Ramamurthi, K

2011-02-01

Single crystals of the organic NLO material, benzaldehyde thiosemicarbazone (BTSC) monohydrate, were grown by slow evaporation method. Solubility of BTSC monohydrate was determined in ethanol at different temperatures. The grown crystals were characterized by single crystal X-ray diffraction analysis to determine the cell parameters and by FT-IR technique to study the presence of the functional groups. Thermogravimetric and differential thermal analyses reveal the thermal stability of the crystal. UV-vis-NIR spectrum shows excellent transmission in the region of 200-1100 nm. Theoretical calculations were carried out to determine the linear optical constants such as extinction coefficient and refractive index. Further the optical nonlinearities of BTSC have been investigated by Z-scan technique with He-Ne laser radiation of wavelength 632.8 nm. Mechanical properties of the grown crystal were studied using Vickers microhardness tester. Second harmonic generation efficiency of the powdered BTSC monohydrate was tested using Nd:YAG laser and it is found to be ∼5.3 times that of potassium dihydrogen orthophosphate. Copyright © 2010 Elsevier B.V. All rights reserved.

Synthesis, growth, crystal structure, optical and third order nonlinear optical properties of quinolinium derivative single crystal: PNQI

NASA Astrophysics Data System (ADS)

Karthigha, S.; Krishnamoorthi, C.

2018-03-01

An organic quinolinium derivative nonlinear optical (NLO) crystal, 1-ethyl-2-[2-(4-nitro-phenyl)-vinyl]-quinolinium iodide (PNQI) was synthesized and successfully grown by slow evaporation solution growth technique. Formation of a crystalline compound was confirmed by single crystal X-ray diffraction. The quinolinium compound PNQI crystallizes in the triclinic crystal system with a centrosymmetric space group of P-1 symmetry. The molecular structure of PNQI was confirmed by 1H NMR and 13C NMR spectral studies. The thermal properties of the crystal have been investigated by thermogravimetric (TG) and differential scanning calorimetry (DSC) studies. The optical characteristics obtained from UV-Vis-NIR spectral data were described and the cut-off wavelength observed at 506 nm. The etching study was performed to analyse the growth features of PNQI single crystal. The third order NLO properties such as nonlinear refractive index (n2), nonlinear absorption coefficient (β) and nonlinear susceptibility (χ (3)) of the crystal were investigated using Z-scan technique at 632.8 nm of Hesbnd Ne laser.

Synthesis, growth, structural, spectroscopic and optical studies of a semiorganic NLO crystal: zinc guanidinium phosphate.

PubMed

Suvitha, A; Murugakoothan, P

2012-02-01

The semi-organic nonlinear optical (NLO) crystal, zinc guanidinium phosphate (ZGuP) has been grown through synthesis between zinc sulphate, guanidine carbonate and orthophosphoric acid from its aqueous solution by slow solvent evaporation technique. Solubility of the synthesized material has been determined for various temperatures using water as solvent. The grown crystal has been characterized by powder X-ray diffraction to confirm the crystal structure. Investigation has been carried out to assign the vibrational frequencies of the grown crystals by Fourier transform infrared spectroscopy technique. (1)H and (13)C FT-NMR have been recorded to elucidate the molecular structure. The optical absorption study confirms the suitability of the crystal for device applications. The second harmonic generation (SHG) efficiency of ZGuP is found to be 1.825 times that of potassium dihydrogen phosphate (KDP). Thermal behavior of the grown crystals has been studied by thermogravimetric and differential thermal analysis. The mechanical properties of the grown crystals have been studied using Vickers microhardness tester. Copyright © 2011 Elsevier B.V. All rights reserved.

High-Rate Assembly of Nanomaterials on Insulating Surfaces Using Electro-Fluidic Directed Assembly.

PubMed

Yilmaz, Cihan; Sirman, Asli; Halder, Aditi; Busnaina, Ahmed

2017-08-22

Conductive or semiconducting nanomaterials-based applications such as electronics and sensors often require direct placement of such nanomaterials on insulating surfaces. Most fluidic-based directed assembly techniques on insulating surfaces utilize capillary force and evaporation but are diffusion limited and slow. Electrophoretic-based assembly, on the other hand, is fast but can only be utilized for assembly on a conductive surface. Here, we present a directed assembly technique that enables rapid assembly of nanomaterials on insulating surfaces. The approach leverages and combines fluidic and electrophoretic assembly by applying the electric field through an insulating surface via a conductive film underneath. The approach (called electro-fluidic) yields an assembly process that is 2 orders of magnitude faster compared to fluidic assembly. By understanding the forces on the assembly process, we have demonstrated the controlled assembly of various types of nanomaterials that are conducting, semiconducting, and insulating including nanoparticles and single-walled carbon nanotubes on insulating rigid and flexible substrates. The presented approach shows great promise for making practical devices in miniaturized sensors and flexible electronics.

Spectroscopic investigations using density functional theory on 2-methoxy- 4(phenyliminomethyl)phenol: A non linear optical material

NASA Astrophysics Data System (ADS)

Hijas, K. M.; Madan Kumar, S.; Byrappa, K.; Geethakrishnan, T.; Jeyaram, S.; Nagalakshmi, R.

2018-03-01

Single crystals of 2-methoxy-4(phenyliminomethyl)phenol were grown from ethanol by slow evaporation solution growth technique. Single crystal X-ray diffraction experiment reveals the crystallization in orthorhombic system having non-centrosymmetric space group C2221. Geometrical optimization by density functional theory method was carried out using Gaussian program and compared with experimental results. Detailed experimental and theoretical vibrational analyses were carried out and the results were correlated to find close agreement. Thermal analyses show the material is thermally stable with a melting point of 159 °C. Natural bond orbital analysis was carried out to explain charge transfer interactions through hydrogen bonding. Relatively smaller HOMO-LUMO band gap favors the non linear optical activity of the molecule. Natural population analysis and molecular electrostatic potential calculations visualize the charge distribution in an isolated molecule. Calculated first-order molecular hyperpolarizability and preliminary second harmonic generation test carried out using Kurtz-Perry technique establish 2-methoxy-4(phenyliminomethyl)phenol crystal as a good non linear optical material. Z-scan proposes the material for reverse saturable absorption.

Thermal, mechanical, optical and conductivity studies of a novel NLO active L-phenylalanine L-phenylalaninium dihydrogenphosphate single crystal

NASA Astrophysics Data System (ADS)

Sujatha, T.; Cyrac Peter, A.; Vimalan, M.; Merline Shyla, J.; Madhavan, J.

2010-08-01

An efficient, novel, semi-organic, nonlinear optical (NLO) material L-phenylalanine L-phenylalaninium dihydrogenphosphate (LPADHP), single crystal of dimension 11×5×2 mm 3, has been grown by the slow evaporation solution growth technique. Single crystal X-ray diffraction studies confirm that the grown crystal belongs to monoclinic system with the space group P2 1. The functional groups present in the crystal were confirmed by the Fourier transform infrared technique. Optical absorption spectrum shows that the material possesses very low absorption in the entire visible region. Thermal analysis confirmed that the crystal is thermally stable up to 161 °C. The frequency dependent dielectric properties of the grown crystal were studied for various temperatures. The second harmonic generation (SHG) efficiency of the grown crystal is 1.2 times greater than that of the potassium dihydrogenphosphate (KDP) single crystal. The laser induced surface damage threshold for the grown crystal was found to be 6.3 GW cm -2 with Nd:YAG laser assembly AC and DC conductivity and photoconductivity experiments are also carried out and the results are discussed.

Growth and physicochemical properties of second-order nonlinear optical 2-amino-5-chloropyridinium trichloroacetate single crystals

NASA Astrophysics Data System (ADS)

Renugadevi, R.; Kesavasamy, R.

2015-09-01

The growth of organic nonlinear optical (NLO) crystal 2-amino-5-chloropyridinium trichloroacetate (2A5CPTCA) has been synthesized and single crystals have been grown from methanol solvent by slow evaporation technique. The grown crystals were subjected to various characterization analyses in order to find out the suitability for device fabrication. Single crystal X-ray diffraction analysis reveals that 2A5CPTCA crystallizes in monoclinic system with the space group Cc. The grown crystal was further characterized by Fourier transform infrared spectral analysis to find out the functional groups. The nuclear magnetic resonance spectroscopy is a research technique that exploits the magnetic properties of certain atomic nuclei. The optical transparency window in the visible and near-IR (200--1100 nm) regions was found to be good for NLO applications. Thermogravimetric analysis and differential thermal analysis were used to study its thermal properties. The powder second harmonic generation efficiency measurement with Nd:YAG laser (1064 nm) radiation shows that the highest value when compared with the standard potassium dihydrogen phosphate crystal.

The microstructure and composition of equilibrium phases formed in hypoeutectic Te-In alloy during solidification

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

Wang, Baoguang

As a key tellurium atoms evaporation source for ultraviolet detection photocathode, the hypoeutectic Te{sub 75}In{sub 25} alloy was prepared by employing a slow solidification speed of about 10{sup −2} K/s. The microstructure and chemical composition of the equilibrium phases formed in the as-prepared alloy were studied in this research work. The experimental results show that the as-prepared Te-In alloy was constituted by primary In{sub 2}Te{sub 5} phase and eutectic In{sub 2}Te{sub 5}/Te phases. The eutectic In{sub 2}Te{sub 5}/Te phases are distributed in the grain boundaries of primary In{sub 2}Te{sub 5} phase. With the slow solidification speed, a pure eutectic Temore » phase without any excessive indium solute was obtained, where Te content of eutectic Te phase is 100 mass%. Moreover, it can be considered that the stress between the In{sub 2}Te{sub 5} and Te phases plays an important role in reducing the tellurium vapor pressure in Te{sub 75}In{sub 25} alloy. - Highlights: • The microstructure of Te-In alloy as an evaporation source was analyzed. • A pure eutectic Te phase was obtained by using a slow solidification speed method. • The relation between vapor pressure and inner-stress in the alloy was discussed.« less

Investigation of inorganic nonlinear optical potassium penta borate tetra hydrate (PPBTH) single crystals grown by slow evaporation method

NASA Astrophysics Data System (ADS)

Arivuselvi, R.; Babu, P. Ramesh

2018-03-01

Borates family crystals were plays vital role in the field of non linear optics (NLO) due to needs of wide range of applications. In this report, NLO crystals (potassium penta borate tetra hydrate (KB5H8O12) are grown by slow evaporation method at room temperature (28° C) and studied their physical properties. The harvested single crystals are transparent with the dimension of 12 × 10 × 6 mm3 and colourless. X-ray diffraction of single crystals reveals that the grown crystal belongs to orthorhombic system with non-centrosymmetric space group Pba2. All the absorbed functional groups are present in the order of inorganic compounds expect 1688 cm-1 because of water (Osbnd H sbnd O blending) molecule present in the pristine. Crystals show transparent in the entire visible region with 5.9 eV optical band gap and also it shows excellence in both second and third order nonlinear optical properties. Crystals can withstand upto 154 °C without any phase changes which is observed using thermal (TGA/DTA) analysis.

Active layer hydrology in an arctic tundra ecosystem: quantifying water sources and cycling using water stable isotopes

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

Throckmorton, Heather M.; Newman, Brent D.; Heikoop, Jeffrey M.

Climate change and thawing permafrost in the Arctic will significantly alter landscape hydro-geomorphology and the distribution of soil moisture, which will have cascading effects on climate feedbacks (CO 2 and CH 4) and plant and microbial communities. Fundamental processes critical to predicting active layer hydrology are not well understood. This study applied water stable isotope techniques (δ 2H and δ 18O) to infer sources and mixing of active layer waters in a polygonal tundra landscape in Barrow, Alaska (USA), in August and September of 2012. Results suggested that winter precipitation did not contribute substantially to surface waters or subsurface activemore » layer pore waters measured in August and September. Summer rain was the main source of water to the active layer, with seasonal ice melt contributing to deeper pore waters later in the season. Surface water evaporation was evident in August from a characteristic isotopic fractionation slope (δ 2H vs δ 18O). Freeze-out isotopic fractionation effects in frozen active layer samples and textural permafrost were indistinguishable from evaporation fractionation, emphasizing the importance of considering the most likely processes in water isotope studies, in systems where both evaporation and freeze-out occur in close proximity. The fractionation observed in frozen active layer ice was not observed in liquid active layer pore waters. Such a discrepancy between frozen and liquid active layer samples suggests mixing of meltwater, likely due to slow melting of seasonal ice. In conclusion, this research provides insight into fundamental processes relating to sources and mixing of active layer waters, which should be considered in process-based fine-scale and intermediate-scale hydrologic models.« less

Active layer hydrology in an arctic tundra ecosystem: quantifying water sources and cycling using water stable isotopes

DOE PAGES

Throckmorton, Heather M.; Newman, Brent D.; Heikoop, Jeffrey M.; ...

2016-04-16

Climate change and thawing permafrost in the Arctic will significantly alter landscape hydro-geomorphology and the distribution of soil moisture, which will have cascading effects on climate feedbacks (CO 2 and CH 4) and plant and microbial communities. Fundamental processes critical to predicting active layer hydrology are not well understood. This study applied water stable isotope techniques (δ 2H and δ 18O) to infer sources and mixing of active layer waters in a polygonal tundra landscape in Barrow, Alaska (USA), in August and September of 2012. Results suggested that winter precipitation did not contribute substantially to surface waters or subsurface activemore » layer pore waters measured in August and September. Summer rain was the main source of water to the active layer, with seasonal ice melt contributing to deeper pore waters later in the season. Surface water evaporation was evident in August from a characteristic isotopic fractionation slope (δ 2H vs δ 18O). Freeze-out isotopic fractionation effects in frozen active layer samples and textural permafrost were indistinguishable from evaporation fractionation, emphasizing the importance of considering the most likely processes in water isotope studies, in systems where both evaporation and freeze-out occur in close proximity. The fractionation observed in frozen active layer ice was not observed in liquid active layer pore waters. Such a discrepancy between frozen and liquid active layer samples suggests mixing of meltwater, likely due to slow melting of seasonal ice. In conclusion, this research provides insight into fundamental processes relating to sources and mixing of active layer waters, which should be considered in process-based fine-scale and intermediate-scale hydrologic models.« less

Electron irradiation induced effects on the physico-chemical properties of L-Arginine Maleate Dihydrate (LAMD) single crystals

NASA Astrophysics Data System (ADS)

Thomas, Prince; Dhole, S. D.; Joseph, Ginson P.

2018-07-01

Single crystals of L-Arginine Maleate Dihydrate (LAMD) have been synthesized by slow solvent evaporation technique and irradiated with 6 MeV electrons at fluences of 0.5 ×1015e /cm2 , 1.0 ×1015e /cm2 and 1.5 ×1015e /cm2 . The Powder X-ray Diffraction (PXRD) studies showed that the intensity of the diffraction peaks of the Electron Beam (EB) irradiated crystals decreases with irradiation fluence. The electron irradiation induced effects on the optical parameters such as cut-off wavelength, band gap, Urbach energy and refractive index have been studied and the results are tabulated. The electronic parameters such as valence electron plasma energy, ℏωp , Penn gap, Ep , Fermi energy, EF and Electronic polarizability, α for pure and irradiated LAMD crystals are calculated. The electrical and thermal properties of the pure and irradiated LAMD crystals are also investigated.

Studies on 2-amino-5-nitropyridinium nitrate (2A5NPN): A semi-organic third order nonlinear optical single crystal

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

Sivasubramani, V.; Pandian, Muthu Senthil, E-mail: senthilpandianm@ssn.edu.in; Ramasamy, P.

2016-05-23

2-amino-5-nitropyridinium nitrate (2A5NPN) is a semi-organic nonlinear optical crystal and optically good quality 2A5NPN single crystals were successfully grown by slow evaporation solution growth technique (SEST) at ambient temperature. The crystallographic structure of the grown crystal was determined by single crystal X-Ray diffraction analysis and it belongs to Monoclinic crystal system with centro symmetric crystalline nature. The crystallinity of the grown crystal was confirmed by powder X-ray diffraction analysis. The other physical properties of grown crystals are also characterized using TG-DTA, UV-Visible NIR, chemical etching, photoconductivity and Z-scan measurements. The Z-scan method reveals that the 2A5NPN crystal possesses multi photonmore » absorption behaviour and the significantly higher third order susceptibility and it is a promising potential NLO material.« less

Synthesis, crystal growth, structural, thermal, optical and mechanical properties of solution grown 4-methylpyridinium 4-hydroxybenzoate single crystal.

PubMed

Sudhahar, S; Krishna Kumar, M; Sornamurthy, B M; Mohan Kumar, R

2014-01-24

Organic nonlinear optical material, 4-methylpyridinium 4-hydroxybenzoate (4MPHB) was synthesized and single crystal was grown by slow evaporation solution growth method. Single crystal and powder X-ray diffraction analyses confirm the structure and crystalline perfection of 4MPHB crystal. Infrared, Raman and NMR spectroscopy techniques were used to elucidate the functional groups present in the compound. TG-DTA analysis was carried out in nitrogen atmosphere to study the decomposition stages, endothermic and exothermic reactions. UV-visible and Photoluminescence spectra were recorded for the grown crystal to estimate the transmittance and band gap energy respectively. Linear refractive index, birefringence, and SHG efficiency of the grown crystal were studied. Laser induced surface damage threshold and mechanical properties of grown crystal were studied to assess the suitability of the grown crystals for device applications. Copyright © 2013 Elsevier B.V. All rights reserved.

Solid state parameters, structure elucidation, High Resolution X-Ray Diffraction (HRXRD), phase matching, thermal and impedance analysis on L-Proline trichloroacetate (L-PTCA) NLO single crystals.

PubMed

Kalaiselvi, P; Raj, S Alfred Cecil; Jagannathan, K; Vijayan, N; Bhagavannarayana, G; Kalainathan, S

2014-11-11

Nonlinear optical single crystal of L-Proline trichloroacetate (L-PTCA) was successfully grown by Slow Evaporation Solution Technique (SEST). The grown crystals were subjected to single crystal X-ray diffraction analysis to confirm the structure. From the single crystal XRD data, solid state parameters were determined for the grown crystal. The crystalline perfection has been evaluated using high resolution X-ray diffractometer. The frequencies of various functional groups were identified from FTIR spectral analysis. The percentage of transmittance was obtained from UV Visible spectral analysis. TGA-DSC measurements indicate the thermal stability of the crystal. The dielectric constant, dielectric loss and ac conductivity were measured by the impedance analyzer. The DC conductivity was calculated by the cole-cole plot method. Copyright © 2014 Elsevier B.V. All rights reserved.

Bulk growth of <001> organic nonlinear optical (NLO) L-arginine 4-nitrophenolate 4-nitrophenol dihydrate (LAPP) single crystals by SR method

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

Pandian, Muthu Senthil, E-mail: senthilpandianm@ssn.edu.in; Sivasubramani, V.; Ramasamy, P.

2015-06-24

A transparent uniaxial L-arginine 4-nitrophenolate 4-nitrophenol dehydrate (LAPP) single crystal having dimension of 20 mm diameter and 45 mm length was grown by Sankaranarayanan-Ramasamy (SR) method with a growth rate of 1 mm per day. Using an identical solution the conventional crystal grown to a dimension of 8×5×5 mm{sup 3} was obtained over a period of 30 days. The crystal structure has been confirmed by single crystal X-ray diffraction measurement. The crystalline perfection of LAPP crystals grown by slow evaporation solution technique (SEST) and SR method were characterized using Vickers microhardness, UV-Vis NIR, chemical etching, dark and photo current measurements. The above study indicatesmore » that the crystal quality of the Sankaranarayanan-Ramasamy (SR) method grown LAPP is good compared to the conventional method grown crystal.« less

Synthesis, crystal structure and antitumor activities of water soluble protonated salt of 20(S)-camptothecin

NASA Astrophysics Data System (ADS)

Lu, Wen; Wang, Yong; Wang, Luna; Zhao, Fengyi; Yang, Shilong; Xi, Chengjie; Yang, Yu; Xu, Li; Chi, Xingwei

2018-03-01

A water soluble camptothecin protonated salt has been synthesized; single crystals were grown by slow evaporation solution growth technique at room temperature and characterized by single crystal X-ray diffraction, FT-IR and 1H NMR. The CPT was protonated as (CPT+H+) cations, the cationic protonation occurred on the N position at pyridine group, which fromed a cation-anion compound with perchlorate ion that determined by X-Ray diffraction. Its activities against Hela (cervix), MCF-7 (breast), A549 (lung), HepG2 (liver) and HUVEC (umbilical vein, normal cell) were investigated. The toxicity of the protonated salt was slightly lower than camptothecin. IC50 values of 7.01 μM against HepG-2 cell, 8.61 μM against A549 cell, 17.82 μM against McF-7 cell, all of them are lower than the IC50 values of CPT against these cells except Hela cell.

Enhancement in ferroelectric, pyroelectric and photoluminescence properties in dye doped TGS crystals

NASA Astrophysics Data System (ADS)

Sinha, Nidhi; Goel, Neeti; Singh, B. K.; Gupta, M. K.; Kumar, Binay

2012-06-01

Pure and dye doped (0.1 and 0.2 mol%) Triglycine Sulfate (TGS) single crystals were grown by slow evaporation technique. A pyramidal coloring pattern, along with XRD and FT-IR studies confirmed the dye doping. Decrease in dielectric constant and increase in Curie temperature (Tc) were observed with increasing doping concentration. Low absorption cut off (231 nm) and high optical transparency (>90%) resulting in large band gap was observed in UV-VIS studies. In addition, strong hyper-luminescent emission bands at 350 and 375 nm were observed in which the relative intensity were found to be reversed as a result of doping. In P-E hysteresis loop studies, a higher curie temperature and an improved and more uniform figure of merit over a large region of the ferroelectric phase were observed. The improved dielectric, optical and ferroelectric/pyroelectric properties make the dye doped TGS crystals better candidate for various opto- and piezo-electronics applications.

Synthesis and structure identification of 2-amino-4, 6- dimethyl pyrimidine with gallic acid and pimelic acid

NASA Astrophysics Data System (ADS)

Mekala, R.; Jagdish, P.; Mathammal, R.

2018-07-01

Reaction of 2-amino-4, 6- dimethyl pyrimidine with carboxylic acid such as gallic acid and pimelic acid, yielded a salt and co-crystal, respectively. The new crystal forms were obtained from slow evaporation technique. The crystal structure and hydrogen bond interaction of the two crystals were determined by single X-ray diffraction analysis. Inter molecular interactions of the compounds were investigated using the 3D Hirshfeld surfaces and the associated 2D fingerprint plots. The functional groups were identified by the FTIR, FT-Raman spectral studies. The presence of carbon and hydrogen in the two samples were identified by the 1H and 13C NMR analysis. The excited energy was observed using UV-Visible spectral analysis. The fluorescence spectra revealed the emission state of the two samples. The thermal behaviour and stability of the two compounds were evaluated by the TGA-DSC analysis.

Nucleation kinetics, crystal growth and optical studies on lithium hydrogen oxalate monohydrate single crystal

NASA Astrophysics Data System (ADS)

Chandran, Senthilkumar; Paulraj, Rajesh; Ramasamy, P.

2017-06-01

Semi-organic lithium hydrogen oxalate monohydrate non-linear optical single crystals have been grown by slow evaporation solution technique at 40 °C. The nucleation parameters such as critical radius, interfacial tension, and critical free energy change have been evaluated using the experimental data. The solubility and the nucleation curve of the crystal at different temperatures have been analyzed. The crystal has a positive temperature coefficient of solubility. The metastable zone width and induction period have been determined for the aqueous solution growth of lithium hydrogen oxalate monohydrate. The UV-vis-NIR spectrum showed this crystal has high transparency. The photoconductivity studies indicate lithium hydrogen oxalate monohydrate has positive photoconductivity behaviour. The low etch pit density observed on (0 0 1) crystal surface and the high resolution x-ray difraction analysis indicate the good quality of the grown crystals

Comparative study of glycine single crystals with additive of potassium nitrate in different concentration ratios

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

Gujarati, Vivek P., E-mail: vivekgujarati@gmail.com; Deshpande, M. P., E-mail: vishwadeshpande@yahoo.co.in; Patel, Kamakshi R.

2016-05-06

Semi-organic crystals of Glycine Potassium Nitrate (GPN) with potential applications in Non linear optics (NLO) were grown using slow evaporation technique. Glycine and Potassium Nitrate were taken in three different concentration ratios of 3:1, 2:1 and 1:1 respectively. We checked the solubility of the material in distilled water at different temperatures and could observe the growth of crystals in 7 weeks time. Purity of the grown crystals was confirmed by Energy Dispersive X-ray Analysis (EDAX) and CHN analysis. GSN Powder X-ray diffraction pattern was recorded to confirm the crystalline nature. To confirm the applications of grown crystals in opto-electronics field,more » UV-Vis-NIR study was carried out. Dielectric properties of the samples were studied in between the frequency range 1Hz to 100 KHz.« less

Synthesis and structural study of 4-(2-chlorophenyl)-2-ethoxy-5,6,7,8,9,10-hexahydrocycloocta[B]pyridine-3-carbonitrile

NASA Astrophysics Data System (ADS)

Fathima, K. Saiadali; Vasumathi, M.; Anitha, K.

2016-05-01

The novel organic material C20H21ClN2O was synthesized by One-Pot synthesis method and the single crystals were grown by slow evaporation solution growth technique. The crystal structure was elucidated by subjecting the grown crystals to the single crystal x-ray diffraction analysis and was refined by full matrix least-squares method to R=0.039 for 2746 reflections. Crystal system of the grown crystal was found to be monoclinic with the space group P21/a and a=9.196(4) Å, b=13.449(4) Å, c=14.818(4) Å, β= 101.542(3)°, V=1795.6(11) Å3 and Z=4. In this crystal structure, cyclooctanone prefers to reside in a chair-boat conformation. The structure is stabilized by attractive molecular force such as CH/π interaction called hydrophobic interaction.

Synthesis, crystal structure, NLO and Hirshfeld surface analysis of 1,2,3-triazolyl chalcone single crystal

NASA Astrophysics Data System (ADS)

Shruthi, C.; Ravindrachary, V.; Guruswamy, B.; Lokanath, N. K.; Kumara, Karthik; Goveas, Janet

2018-05-01

Needle shaped brown coloured single crystal of the title compound was grown by slow evaporation technique using methanol as solvent. The grown crystal was characterized using FT-IR, Single crystal XRD, UV-visible and NLO studies. Crystal structure was confirmed by FT-IR study and the functional groups were identified. XRD study reveals that the crystal belongs to orthorhombic crystal system with pnaa space group and the corresponding cell parameters were calculated. UV-visible spectrum shows that the crystal is transparent in the entire visible region and absorption takes place in the UV-range. NLO efficiency of the crystal obtained 0.66 times that of urea was determined by SHG test. The intermolecular interaction and percentage contribution of each individual atom in the crystal lattice was quantized using Hirshfeld surface and 2D finger print analysis.

Spectroscopic and theoretical study of the charge transfer interaction effect on the vibrational modes and nonlinear optical properties in L-asparaginium nitrate crystal

NASA Astrophysics Data System (ADS)

Elleuch, Nabil; Abid, Younes; Feki, Habib

2016-09-01

Single crystals of L-asparaginium nitrate (LAsnN) were grown by slow evaporation technique. To confirm the crystalline nature of the obtained compound, samples were the subject of an XRPD. The density functional theory (DFT) computations were carried out at B3LYP/6-31G (d) level to reach the optimized geometry, the vibrational spectra and the NLO properties. The excellent agreement between simulated and observed vibrational spectra led to a reliable vibrational assignment. To demonstrate the various charge transfer interactions that stabilize the compound and led to the high nonlinear optical activity, NBO analysis was performed. Also, owing to the hydrogen bond formation, a lowering in the HOMO-LUMO energy gap is noticed. Moreover, as a result of the charge transfer interactions, the symmetry of the nitrate ions was lost and some forbidden modes were excited.

Characterization of potassium bromide crystals grown in the aqueous solution of picric acid

NASA Astrophysics Data System (ADS)

Maheswari, J. Uma; Krishnan, C.; Kalyanaraman, S.; Selvarajan, P.

2016-12-01

Potassium bromide crystals were grown in the aqueous solution of picric acid by slow evaporation technique at room temperature. X-ray Diffraction (XRD) analysis ensures that the grown sample is in Fm3m space group and FCC structure. Energy Dispersive X-ray Spectroscopy (EDX) reveals the presence of elements in the title compound. UV-Vis-NIR spectrum reveals that the grown sample is a promising nonlinear optical (NLO) material. FTIR analysis confirms the functional groups present in the sample. The thermogravimetric (TG) and differential thermogravimetric (DTA) analyses ensure that the sample material is thermally stable up to 160 °C. The second harmonic efficiency of the sample is 1.3 times greater than that of standard KDP. The mechanical strength of the grown sample is estimated by Vickers microhardness tester. The electrical properties were investigated by impedance analysis and the results of various studies of the grown crystals are discussed.

Preparation, crystal structure, vibrational spectral and density functional studies of bis (4-nitrophenol)-2,4,6-triamino-1,3,5-triazine monohydrate

NASA Astrophysics Data System (ADS)

Kanagathara, N.; Marchewka, M. K.; Drozd, M.; Renganathan, N. G.; Gunasekaran, S.; Anbalagan, G.

2013-10-01

An organic-organic salt, bis (4-nitrophenol) 2,4,6-triamino 1,3,5-triazine monohydrate (BNPM) has been prepared by slow evaporation technique at room temperature. Single crystal X-ray diffraction analysis reveals that the compound crystallizes in triclinic system with centrosymmetric space group P-1. IR and Raman spectra of BNPM have been recorded and analyzed. The study has been extended to confocal Raman spectral analysis. Band assignments have been made for the melamine and p-nitrophenol molecules. Vibrational spectra have also been discussed on the basis of quantum chemical density functional theory calculations using Firefly (PC GAMESS) Version 7.1 G. Vibrational frequencies are calculated and scaled values are compared with the experimental one. The Mulliken charges, HOMO-LUMO orbital energies are calculated and analyzed. The chemical structure of the compound was established by 1H NMR and 13C NMR spectra.

Transfer-arm evaporator cell for rapid loading and deposition of organic thin films.

PubMed

Greiner, M T; Helander, M G; Wang, Z B; Lu, Z H

2009-12-01

Described herein is a transfer-arm evaporator cell (TAE-cell), which allows for rapid loading of materials into vacuum for low-temperature sublimation deposition of thin films. This design can be incorporated with an existing analysis system for convenient in situ thin film characterization. This evaporator is especially well suited for photoemission characterization of organic semiconductor interfaces. Photoemission is one of the most important techniques for characterizing such, however, it generally requires in situ sample preparation. The ease with which materials can be loaded and evaporated with this design increases the throughput of in situ photoemission characterization, and broadens the research scope of the technique. Here, we describe the design, operation, and performance of the TAE-cell.

Probing the Evaporation Dynamics of Ethanol/Gasoline Biofuel Blends Using Single Droplet Manipulation Techniques.

PubMed

Corsetti, Stella; Miles, Rachael E H; McDonald, Craig; Belotti, Yuri; Reid, Jonathan P; Kiefer, Johannes; McGloin, David

2015-12-24

Using blends of bioethanol and gasoline as automotive fuel leads to a net decrease in the production of harmful emission compared to the use of pure fossil fuel. However, fuel droplet evaporation dynamics change depending on the mixing ratio. Here we use single particle manipulation techniques to study the evaporation dynamics of ethanol/gasoline blend microdroplets. The use of an electrodynamic balance enables measurements of the evaporation of individual droplets in a controlled environment, while optical tweezers facilitate studies of the behavior of droplets inside a spray. Hence, the combination of both methods is perfectly suited to obtain a complete picture of the evaporation process. The influence of adding varied amounts of ethanol to gasoline is investigated, and we observe that droplets with a greater fraction of ethanol take longer to evaporate. Furthermore, we find that our methods are sensitive enough to observe the presence of trace amounts of water in the droplets. A theoretical model, predicting the evaporation of ethanol and gasoline droplets in dry nitrogen gas, is used to explain the experimental results. Also a theoretical estimation of the saturation of the environment, with other aerosols, in the tweezers is carried out.

Evaporation kinetics of sessile water droplets on micropillared superhydrophobic surfaces.

PubMed

Xu, Wei; Leeladhar, Rajesh; Kang, Yong Tae; Choi, Chang-Hwan

2013-05-21

Evaporation modes and kinetics of sessile droplets of water on micropillared superhydrophobic surfaces are experimentally investigated. The results show that a constant contact radius (CCR) mode and a constant contact angle (CCA) mode are two dominating evaporation modes during droplet evaporation on the superhydrophobic surfaces. With the decrease in the solid fraction of the superhydrophobic surfaces, the duration of a CCR mode is reduced and that of a CCA mode is increased. Compared to Rowan's kinetic model, which is based on the vapor diffusion across the droplet boundary, the change in a contact angle in a CCR (pinned) mode shows a remarkable deviation, decreasing at a slower rate on the superhydrophobic surfaces with less-solid fractions. In a CCA (receding) mode, the change in a contact radius agrees well with the theoretical expectation, and the receding speed is slower on the superhydrophobic surfaces with lower solid fractions. The discrepancy between experimental results and Rowan's model is attributed to the initial large contact angle of a droplet on superhydrophobic surfaces. The droplet geometry with a large contact angle results in a narrow wedge region of air along the contact boundary, where the liquid-vapor diffusion is significantly restricted. Such an effect becomes minor as the evaporation proceeds with the decrease in a contact angle. In both the CCR and CCA modes, the evaporative mass transfer shows the linear relationship between mass(2/3) and evaporation time. However, the evaporation rate is slower on the superhydrophobic surfaces, which is more significant on the surfaces with lower solid fractions. As a result, the superhydrophobic surfaces slow down the drying process of a sessile droplet on them.

Laboratory prototype flash evaporator

NASA Technical Reports Server (NTRS)

Gaddis, J. L.

1972-01-01

A laboratory prototype flash evaporator that is being developed as a candidate for the space shuttle environmental control system expendable heat sink is described. The single evaporator configuration uses water as an evaporant to accommodate reentry and on-orbit peak heat loads, and Freon 22 for terrestrial flight phases below 120,000 feet altitude. The design features, fabrication techniques used for the prototype unit, redundancy considerations, and the fluid temperature control arrangement are reported in detail. The results of an extensive test program to determine the evaporator operational characteristics under a wide variety of conditions are presented.

Dynamic Morphologies and Stability of Droplet Interface Bilayers

NASA Astrophysics Data System (ADS)

Guiselin, Benjamin; Law, Jack O.; Chakrabarti, Buddhapriya; Kusumaatmaja, Halim

2018-06-01

We develop a theoretical framework for understanding dynamic morphologies and stability of droplet interface bilayers (DIBs), accounting for lipid kinetics in the monolayers and bilayer, and droplet evaporation due to imbalance between osmotic and Laplace pressures. Our theory quantitatively describes distinct pathways observed in experiments when DIBs become unstable. We find that when the timescale for lipid desorption is slow compared to droplet evaporation, the lipid bilayer will grow and the droplets approach a hemispherical shape. In contrast, when lipid desorption is fast, the bilayer area will shrink and the droplets eventually detach. Our model also suggests there is a critical size below which DIBs can become unstable, which may explain experimental difficulties in miniaturizing the DIB platform.

Leidenfrost phenomenon-assisted thermal desorption (LPTD) and its application to open ion sources at atmospheric pressure mass spectrometry.

PubMed

Saha, Subhrakanti; Chen, Lee Chuin; Mandal, Mridul Kanti; Hiraoka, Kenzo

2013-03-01

This work describes the development and application of a new thermal desorption technique that makes use of the Leidenfrost phenomenon in open ion sources at atmospheric pressure for direct mass spectrometric detection of ultratrace levels of illicit, therapeutic, and stimulant drugs, toxicants, and peptides (molecular weight above 1 kDa) in their unaltered state from complex real world samples without or with minor sample pretreatment. A low temperature dielectric barrier discharge ion source was used throughout the experiments and the analytical figures of merit of this technique were investigated. Further, this desorption technique coupled with other ionization sources such as electrospray ionization (ESI) and dc corona discharge atmospheric pressure chemical ionization (APCI) in open atmosphere was also investigated. The use of the high-resolution 'Exactive Orbitrap' mass spectrometer provided unambiguous identification of trace levels of the targeted compounds from complex mixtures and background noise; the limits of detection for various small organic molecules and peptides treated with this technique were at the level of parts per trillion and 10(-9) M, respectively. The high sensitivity of the present technique is attributed to the spontaneous enrichment of analyte molecules during the slow evaporation of the solvent, as well as to the sequential desorption of molecules from complex mixtures based on their volatilities. This newly developed desorption technique is simple and fast, while molecular ions are observed as the major ions.

Physico-chemical characterization, density functional theory (DFT) studies and Hirshfeld surface analysis of a new organic optical material: 1H-benzo[d]imidazol-3-ium-2,4,6-trinitrobenzene-1,3 bis(olate)

NASA Astrophysics Data System (ADS)

Dhamodharan, P.; Sathya, K.; Dhandapani, M.

2017-10-01

A novel organic crystal, 1H-benzo[d]imidazol-3-ium-2,4,6-trinitrobenzene-1,3 bis(olate) (BITB), was synthesized. Single crystals of BITB were harvested by solution growth-slow evaporation technique. 1H and 13C NMR spectroscopic techniques were utilized to confirm the presence of various types of carbons and protons in BITB. Single crystal XRD confirms that BITB crystallizes in monoclinic system with a space group of P21/n. The suitability of this material for optical applications was assessed by optical absorption, transmittance, reflectance and refractive index spectroscopic techniques. Gaussian 09 program at B3LYP/6-311++G(d,p) level of basis set as used for the optimization of molecular structure of BITB. Greater first order hyperpolarizability value of BITB is due to intensive hydrogen bond network in the crystal. The value is 15 times greater than that of Urea, a reference standard. Computation of frontier molecular orbitals and electrostatic potential surface helped to understand the electron density and reactive sites in BITB. The material was thermally stable up to 220 °C. Hirshfeld surface analysis was performed to quantify the covalent and non covalent interactions.

Growth, structural, spectral, mechanical, thermal and dielectric characterization of phosphoric acid admixtured L-alanine (PLA) single crystals.

PubMed

Rose, A S J Lucia; Selvarajan, P; Perumal, S

2011-10-15

Phosphoric acid admixtured L-alanine (PLA) single crystals were grown successfully by solution method with slow evaporation technique at room temperature. Crystals of size 18 mm×12 mm×8 mm have been obtained in 28 days. The grown crystals were colorless and transparent. The solubility of the grown samples has been found out at various temperatures. The lattice parameters of the grown crystals were determined by X-ray diffraction technique. The reflection planes of the sample were confirmed by the powder X-ray diffraction study and diffraction peaks were indexed. Fourier transform infrared (FTIR) studies were used to confirm the presence of various functional groups in the crystals. UV-visible transmittance spectrum was recorded to study the optical transparency of grown crystal. The nonlinear optical (NLO) property of the grown crystal was confirmed by Kurtz-Perry powder technique and a study of its second harmonic generation efficiency in comparison with potassium dihydrogen phosphate (KDP) has been made. The mechanical strength of the crystal was estimated by Vickers hardness test. The grown crystals were subjected to thermo gravimetric and differential thermal analysis (TG/DTA). The dielectric behavior of the sample was also studied. Copyright © 2011 Elsevier B.V. All rights reserved.

Development of a household waste treatment subsystem, volume 1. [with water conservation features

NASA Technical Reports Server (NTRS)

Gresko, T. M.; Murray, R. W.

1973-01-01

The domestic waste treatment subsystem was developed to process the daily liquid and non-metallic solid wastes provided by a family of four people. The subsystem was designed to be connected to the sewer line of a household which contained water conservation features. The system consisted of an evaporation technique to separate liquids from solids, an incineration technique for solids reduction, and a catalytic oxidizer for eliminating noxious gases from evaporation and incineration processes. All wastes were passed through a grinder which masticated the solids and deposited them in a settling tank. The liquids were transferred through a cleanable filter into a holding tank. From here the liquids were sprayed into an evaporator and a spray chamber where evaporation occurred. The resulting vapors were processed by catalytic oxidation. Water and latent energy were recovered in a combination evaporator/condenser heat exchanger. The solids were conveyed into an incinerator and reduced to ash while the incineration gases were passed through the catalytic oxidizer along with the processed water vapor.

Electron beam assisted field evaporation of insulating nanowires/tubes

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

Blanchard, N. P., E-mail: nicholas.blanchard@univ-lyon1.fr; Niguès, A.; Choueib, M.

2015-05-11

We demonstrate field evaporation of insulating materials, specifically BN nanotubes and undoped Si nanowires, assisted by a convergent electron beam. Electron irradiation leads to positive charging at the nano-object's apex and to an important increase of the local electric field thus inducing field evaporation. Experiments performed both in a transmission electron microscope and in a scanning electron microscope are presented. This technique permits the selective evaporation of individual nanowires in complex materials. Electron assisted field evaporation could be an interesting alternative or complementary to laser induced field desorption used in atom probe tomography of insulating materials.

Growth and characterization of an efficient new NLO single crystal L-phenylalanine D-methionine for frequency conversion and optoelectronic applications

NASA Astrophysics Data System (ADS)

Sangeetha, P.; Jayaprakash, P.; Nageshwari, M.; Rathika Thaya Kumari, C.; Sudha, S.; Prakash, M.; Vinitha, G.; Lydia Caroline, M.

2017-11-01

Optically active single crystals of L-phenylalanine D-methionine (LPDM) were grown by slow evaporation technique by co-crystallization of amino acids L-phenylalanine and D-methionine in water. The unit cell dimensions have been identified from single crystal X-ray diffraction technique. The existences of various hydrocarbyls were examined by FTIR and FT-Raman spectroscopy. The carbon and hydrogen environment of the grown crystals were analyzed by FT NMR spectrum. The optical absorption studies show that the crystal is transparent in the visible region with a lower cut-off wavelength of 259 nm and there by optical band gap energy Eg is calculated to be 5.35 eV. The Urbach energy, extinction coefficient, reflectance were calculated from UV-absorption data. Further, the thermal stability and accurate melting point has been investigated by TG/DSC techniques. The Kurtz powder SHG was confirmed using Nd:YAG laser with fundamental wavelength of 1064 nm. The dielectric behavior of the specimen has been determined for various temperatures (313 K, 333 K, 353 K, 373 K) at different frequencies. Fluorescence study and the time resolved decay calculation was also performed for the LPDM crystal. Optical nonlinear susceptibility was measured in LPDM and the real and imaginary part of χ3 was evaluated by Z-scan technique using open and closed apertures.

Development of a laboratory prototype spraying flash evaporator.

NASA Technical Reports Server (NTRS)

Gaddis, J. L.

1972-01-01

A functional description of the flash evaporator that is being developed as a candidate for the Space Shuttle Environmental Control System thermal control is presented. A single evaporator configuration uses water as an evaporant to accommodate on-orbit peak heat loads and Freon 22 for terrestrial flight phases below 120,000 ft altitude. Development history, test plans, and operational characteristics are described. Detailed information is included to show: design features, fabrication techniques used for a prototype unit, redundancy considerations, and the control arrangement.

What water isotopes tell us about water cycle responses to climate change

NASA Astrophysics Data System (ADS)

Raudzens Bailey, A.; Singh, H. A.; Nusbaumer, J. M.; Dee, S.; Blossey, P. N.; Posmentier, E. S.

2017-12-01

The water cycle is expected to respond strongly to rising global temperatures. Models predict regional imbalances in evaporation and precipitation will intensify, resulting in a slowing of the large-scale circulation. This slowing will extend the moisture length scale by increasing the amount of time water resides in the atmosphere. However, verifying these changes observationally is challenging. Isotope ratios in water vapor and precipitation represent an integrated record of moisture's journey from evaporative source to precipitation sink. Consequently, they provide a unique opportunity to identify changes in moisture length scale associated with shifts in regional hydrologic balance. Leveraging satellite retrievals, box models, climate simulations, and in situ data, this presentation demonstrates how water isotope ratios can be used to estimate water cycle changes over the historical period and into the future. These changes are closely linked to variations in the divergence of atmospheric moisture fluxes, which result from variations in specific humidity, wind direction, and wind speed. This presentation highlights the extent to which isotopic measurements allow us to track changes in the dynamic, or wind-driven, component of moisture transport and to investigate whether remote moisture contributions are becoming increasingly important in augmenting local precipitation.

Synthesis of nanocrystalline ZnO thin films by electron beam evaporation

NASA Astrophysics Data System (ADS)

Kondkar, V.; Rukade, D.; Bhattacharyya, V.

2018-05-01

Nanocrystalline ZnO thin films have potential for applications in variety of optoelectronic devices. In the present study, nanocrystalline thin films of ZnO are grown on fused silica substrate using electron beam (e-beam) evaporation technique. Phase identification is carried out using Glancing angle X-ray diffraction (GAXRD) and Raman spectroscopy. Ultraviolet-Visible (UV-Vis) spectroscopic analysis is carried out to calculate energy band gap of the ZnO film. Surface morphology of the film is investigated using atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). Highly quality nanocrystalline thin films of hexagonal wurtzite ZnO are synthesized using e-beam evaporation technique.

Measurements of evaporation from a mine void lake and testing of modelling approaches

NASA Astrophysics Data System (ADS)

McJannet, David; Hawdon, Aaron; Van Niel, Tom; Boadle, Dave; Baker, Brett; Trefry, Mike; Rea, Iain

2017-12-01

Pit lakes often form in the void that remains after open cut mining operations cease. As pit lakes fill, hydrological and geochemical processes interact and these need to be understood for appropriate management actions to be implemented. Evaporation is important in the evolution of pit lakes as it acts to concentrate various constituents, controls water level and changes the thermal characteristics of the water body. Despite its importance, evaporation from pit lakes is poorly understood. To address this, we used an automated floating evaporation pan and undertook measurements at a pit lake over a 12 month period. We also developed a new procedure for correcting floating pan evaporation estimates to lake evaporation estimates based on surface temperature differences. Total annual evaporation was 2690 mm and reflected the strong radiation inputs, high temperatures and low humidity experienced in this region. Measurements were used to test the performance of evaporation estimates derived using both pan coefficient and aerodynamic modelling techniques. Daily and monthly evaporation estimates were poorly reproduced using pan coefficient techniques and their use is not recommended for such environments. Aerodynamic modelling was undertaken using a range of input datasets that may be available to those who manage pit lake systems. Excellent model performance was achieved using over-water or local over-land meteorological observations, particularly when the sheltering effects of the pit were considered. Model performance was reduced when off-site data were utilised and differences between local and off-site vapor pressure and wind speed were found to be the major cause.

Synthesis, structural, optical and thermal studies of an organic nonlinear optical 4-aminopyridinium maleate single crystal.

PubMed

Pandi, P; Peramaiyan, G; Kumar, M Krishna; Kumar, R Mohan; Jayavel, R

2012-03-01

Synthesis and growth of a novel organic nonlinear optical (NLO) crystal of 4-aminopyridinium maleate (4APM) in larger size by the slow evaporation solution growth technique are reported. Single crystal and powder X-ray diffraction analyses reveal that 4APM crystallizes in monoclinic system with space group P2(1) with cell parameters a=8.140(4)Å, b=5.457(5)Å, c=10.926(10)Å and volume=481.4(7)Å(3). The grown crystal has been characterized by Fourier transform infrared and UV-visible spectral analyses. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) have been carried out to study its thermal properties. Dielectric measurements have been carried out to study the distribution of charges within the crystal. The mechanical strength of the crystal has been studied by using Vickers' microhardness test. The etching studies have been carried out on the grown crystal. The Kurtz and Perry powder SHG technique confirms the NLO property of the grown crystal and the SHG efficiency of 4APM was found to be 4.8 times greater than that of KDP crystal. Copyright © 2011 Elsevier B.V. All rights reserved.

Growth, nonlinear optical, thermal, dielectric and laser damage threshold studies of semiorganic crystal: monohydrate piperazine hydrogen phosphate.

PubMed

Krishnan, P; Gayathri, K; Bhagavannarayana, G; Gunasekaran, S; Anbalagan, G

2013-02-01

Monohydrate piperazine hydrogen phosphate (MPHP), a semi organic nonlinear optical material has been synthesized and single crystals were grown from aqueous solution by slow evaporation technique. Single crystal X-ray diffraction study on grown crystal reveals that they belong to monoclinic crystal system with space group P2(1)/c; (a=6.39Å; b=12.22Å; c=11.16Å; β=97.14°; V=864Å(3)). The structural perfection of the grown crystal was analyzed by high-resolution X-ray diffraction (HRXRD) rocking curve measurements. FTIR spectrum confirms the presence of the functional groups in synthesized material. UV-Vis spectrum indicates that the crystal is transparent in the entire visible region with a lower cut off wavelength of 387 nm. The variation of dielectric properties of the grown crystal with respect to frequency has been investigated at different temperatures. Thermal analysis carried out on the MPHP crystal shows that the crystal is stable up to 135°C. Relative powder second harmonic generation efficiency tested by Kurtz-Perry powder technique, which was about 0.638 times that of Potassium dihydrogen phosphate. Copyright © 2012 Elsevier B.V. All rights reserved.

Experimental and theoretical investigations of non-centrosymmetric 8-hydroxyquinolinium dibenzoyl-(L)-tartrate methanol monohydrate single crystal

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

Sudharsana, N.; Krishnakumar, V.; Nagalakshmi, R., E-mail: nagaphys@yahoo.com

Graphical abstract: ORTEP diagram of HQDBT. - Highlights: • Single crystal XRD and NMR studies confirm the formation of the title compound. • SHG efficiency was found to be 0.6 times that of KDP. • First-order hyperpolarizability (β) was calculated using HF and B3LYP methods. - Abstract: A novel 8-hydroxyquinolinium dibenzoyl-(L)-tartrate methanol monohydrate crystal has been grown by slow evaporation technique. The single crystal X-ray diffraction analysis has been done for the title compound and is found to crystallize in orthorhombic space group P2{sub 1}2{sub 1}2{sub 1}. The optical absorption cut-off wavelength is found to be 440 nm. The vibrationalmore » analysis has been carried out to assess the functional groups present in the title compound. The molecular structure of the title compound has been confirmed by nuclear magnetic resonance spectroscopy. Thermogravimetric, differential scanning calorimetric and differential thermal analyses reveal the melting point and thermal stability of the title compound. The second harmonic generation efficiency is confirmed by Kurtz–Perry powder technique. Further quantum chemical calculations are performed using Gaussian 03 software.« less

Controlled release of agrochemicals intercalated into montmorillonite interlayer space.

PubMed

Wanyika, Harrison

2014-01-01

Periodic application of agrochemicals has led to high cost of production and serious environmental pollution. In this study, the ability of montmorillonite (MMT) clay to act as a controlled release carrier for model agrochemical molecules has been investigated. Urea was loaded into MMT by a simple immersion technique while loading of metalaxyl was achieved by a rotary evaporation method. The successful incorporation of the agrochemicals into the interlayer space of MMT was confirmed by several techniques, such as, significant expansion of the interlayer space, reduction of Barrett-Joyner-Halenda (BJH) pore volumes and Brunauer-Emmett-Teller (BET) surface areas, and appearance of urea and metalaxyl characteristic bands on the Fourier-transform infrared spectra of the urea loaded montmorillonite (UMMT) and metalaxyl loaded montmorillonite (RMMT) complexes. Controlled release of the trapped molecules from the matrix was done in water and in the soil. The results reveal slow and sustained release behaviour for UMMT for a period of 10 days in soil. For a period of 30 days, MMT delayed the release of metalaxyl in soil by more than 6 times. It is evident that MMT could be used to improve the efficiency of urea and metalaxyl delivery in the soil.

Controlled Release of Agrochemicals Intercalated into Montmorillonite Interlayer Space

PubMed Central

2014-01-01

Periodic application of agrochemicals has led to high cost of production and serious environmental pollution. In this study, the ability of montmorillonite (MMT) clay to act as a controlled release carrier for model agrochemical molecules has been investigated. Urea was loaded into MMT by a simple immersion technique while loading of metalaxyl was achieved by a rotary evaporation method. The successful incorporation of the agrochemicals into the interlayer space of MMT was confirmed by several techniques, such as, significant expansion of the interlayer space, reduction of Barrett-Joyner-Halenda (BJH) pore volumes and Brunauer-Emmett-Teller (BET) surface areas, and appearance of urea and metalaxyl characteristic bands on the Fourier-transform infrared spectra of the urea loaded montmorillonite (UMMT) and metalaxyl loaded montmorillonite (RMMT) complexes. Controlled release of the trapped molecules from the matrix was done in water and in the soil. The results reveal slow and sustained release behaviour for UMMT for a period of 10 days in soil. For a period of 30 days, MMT delayed the release of metalaxyl in soil by more than 6 times. It is evident that MMT could be used to improve the efficiency of urea and metalaxyl delivery in the soil. PMID:24696655

Technique for the control of the crystal habit of ultrafine particles in the gas-evaporation technique

NASA Astrophysics Data System (ADS)

Kasukabe, S.; Mihama, K.

1986-12-01

Magnesium ultrafine particles have clear-cut habits such as hexagonal plates and polyhedra. When magnesium is evaporated downwards using a tube with holes at the bottom, hexagonal plates are formed exclusively throughout the smoke. Their size is controlled by selecting an inert gas. The growth process of an hexagonal plate can be considered to be a coalescent growth of other hexagonal plates.

Externally Induced Evaporation of Young Stellar Disks in Orion

NASA Technical Reports Server (NTRS)

Johnstone, D.; Hollenbach, D.; Shu, F.

1996-01-01

In this paper we propose a model for the evaporation of disks around young low-mass stars by external sources of high energy photons. Two evaporation techniques are possible. Lyman continuum radiation can ionize hydrogen at the disk surface powering a steady thermal ionized disk-wind, or FUV radiation can heat the disk through photo-electric grain processes powering a slower thermal neutral disk-wind. Applying these two models to the evaporating objects in the Trapezium produces a satisfactory solution to both the mass-loss rate and size of the ionized envelopes.

Reinvestigation of growth of 'L-valine zinc sulphate' crystal.

PubMed

Srinivasan, Bikshandarkoil R; Jyai, Rita N

2014-01-01

A reinvestigation of the growth of l-valine zinc sulphate crystal is reported. The slow evaporation of an aqueous solution containing l-valine and zinc sulphate heptahydrate results in the fractional crystallization of l-valine and not the organic inorganic hybrid nonlinear optical l-valine zinc sulphate crystal, as reported by Puhal Raj and Ramachandra Raja (2012). Copyright © 2013 Elsevier B.V. All rights reserved.

Columnar-thin-film acquisition of fingerprint topology

NASA Astrophysics Data System (ADS)

Shaler, Robert C.; Lakhtakia, Akhlesh; Rogers, Jessica W.; Pulsifer, Drew P.; Martín-Palma, Raúl J.

2011-01-01

Fingerprint visualization obtained from physical evidence taken from crime scenes for subsequent comparison typically requires the use of physical and chemical techniques. One physical technique to visualize or develop sebaceous fingerprints on various surfaces employs the deposition of metals such as gold and zinc thereon. We have developed a different vacuum technology: the conformal-evaporated-film-by-rotation technique to deposit dense columnar thin films (CTFs) on latent fingerprints on different types of surfaces. Sample fingerprints, acting as nonplanar substrates, deposited on different surfaces were placed in a vacuum chamber with the fingerprint side facing a boat containing an evaporant material such as chalcogenide glass. Thermal evaporation of the solid material led to the formation of a dense CTF on the fingerprint, thereby capturing the topographical texture with high resolution. Our results show that it is possible to acquire the topology of latent fingerprints on nonporous surfaces. Additionally, deposition of CTFs on overlapping fingerprints suggested ours may be a technique for elucidating the sequence of deposition of the fingerprints at the scene.

Columnar-thin-film acquisition of fingermark topology

NASA Astrophysics Data System (ADS)

Shaler, Robert C.; Lakhtakia, Akhlesh; Rogers, Jessica W.; Pulsifer, Drew P.; Martín-Palma, Raúl J.

2010-08-01

Fingerprint visualization obtained from physical evidence taken from crime scenes for subsequent comparison typically requires the use of physical and chemical techniques. One physical technique to visualize or develop sebaceous fingerprints on various surfaces employs the deposition of metals such as gold and zinc thereon. We have developed a different vacuum technology: the conformal-evaporated-film-by-rotation technique to deposit dense columnar thin films (CTFs) on latent fingerprints on different types of surfaces. Sample fingerprints, acting as nonplanar substrates, deposited on different surfaces were placed in a vacuum chamber with the fingerprint side facing a boat containing an evaporant material such as chalcogenide glass. Thermal evaporation of the solid material led to the formation of a dense CTF on the fingerprint, thereby capturing the topographical texture with high resolution. Our results show that it is possible to acquire the topology of latent fingerprints on non-porous surfaces. Additionally, deposition of CTFs on overlapping fingerprints suggested ours may be a technique for elucidating the sequence of deposition of the fingerprints at the scene.

Effects of chilling rate and spray-chilling on weight loss and tenderness in beef strip loin steaks.

PubMed

Prado, C S; de Felício, P E

2010-10-01

We evaluated the effects of chilling rate and the use of a spray-chilling system on the weight loss by evaporation on carcasses. We also evaluated the effects on meat purge in vacuum package, cooking losses, and on parameters related to the tenderness of strip loin steaks (M. longissimus lumborum). Forty non-castrated males of approximately 12 months old, finished in feed-lot were harvested in 16 Montana cattle (a composite breed), and 24 SimmentalxNellore crossbred cattle. After bleeding, the bodies were electrically stimulated and assigned to one of the four treatments: conventional air-chilling (CAC), conventional spray-chilling (CSC), slow air-chilling (SAC), and slow spray-chilling (SSC). Strip loin steaks (M. longissimus lumborum) of approximately 2.5 cm thick were removed, vacuum packed and aged for 7, 14, 30 or 60 days. Samples were analyzed for sarcomere length, myofibrillar fragmentation index, Warner-Bratzler shear force, and weight losses by purge and cooking. Spraying was efficient in reducing weight loss by evaporation (P<0.05). Effects of treatments and aging period on purge losses were observed, where samples from sprayed carcasses or aged cuts showed higher losses. Cooking losses were not affected either by spraying or aging. The slow chilling, with or without spraying, was more efficient in producing strip loin steaks with lower average shear force and longer sarcomere. The myofibrillar fragmentation index increased with aging time, but was not affected by carcasses spraying. Copyright (c) 2010 The American Meat Science Association. Published by Elsevier Ltd. All rights reserved.

Key optoelectronic properties of Diiodo-bis(carbamide)-zinc(II): An experimental and computational investigation

NASA Astrophysics Data System (ADS)

Shkir, Mohd.; Irfan, Ahmad; AlFaify, S.; Ganesh, V.; Arora, M.; Muhammad, Shabbir; Al-Sehemi, Abdullah G.; Yahia, I. S.

2018-03-01

Large size single crystals of Diiodo-bis(carbamide)-zinc(II) [ZnI2. 2[CO(NH2)2] were grown successfully for the first time by slow evaporation techniques at room temperature within the evaporation time of two weeks. The single phase and high crystalline nature of the grown crystals was confirmed by X-ray diffraction analysis. Quantum chemically the geometrical parameters were found in good correlation with experimental values calculated at B3LYP/6-31G* (LANL2DZ), B2LYPD/6-31G* (LANL2DZ), M062X/6-31G* (LANL2DZ) and MP2/6-31G* (LANL2DZ) level of theories. Additionally, the experimental vibrational modes also have shown a good agreement with calculated ones. The optical transparency and band gap were calculated and found to be ∼80% and 4.706 eV, respectively. The calculated value of HOMO-LUMO gap was found in correlation with experimental energy gap. The electronic properties were investigated by shedding light on the frontier molecular orbitals, partial density of states (PDOS), and total density of states (TDOS). The mechanical and dielectric studies show that the grown crystals possess quite good mechanical strength and dielectric constant. The dielectric loss revealed that the grown crystal contains low defects. The total ac electrical conductivity was increased with frequency and the frequency components confirm the sudden hoping mechanism in the grown crystal.

Green synthesis, characterization and some physico-chemical studies on a novel intermolecular compound; 4-nitro-o-phenylenediamine-N, N-dimethylaminobenzaldehyde system

NASA Astrophysics Data System (ADS)

Rai, U. S.; Singh, Manjeet; Rai, R. N.

2017-09-01

An inter-molecular compound (IMC) L1 was synthesized by taking 1:1 molar ratio of p-nitro-o-phenylenediamine (NOPDA) and N, N-dimethylaminobenzaldehyde (DMAB) via thermally initiated solid state reaction. It was characterized by X-ray diffraction, spectral and optical studies. The single crystal of the (L1) was grown from saturated solution of ethanol using slow evaporation technique at 29 °C. From the single crystal X-ray diffraction analysis, it can be inferred that it crystallizes in triclinic unit cell with P-1 space group (CCDC No 1422765). Absorption spectrum of IMC (L1) shows a band at 318 nm attributed to the intra-molecular charge-transfer (ICT) excited state absorption and the other band at 376 nm is due to n→π* transition. The IMC (L1) shows a strong fluorescence at 418 nm with a Stokes shift (≈100 nm) and quantum efficiency (0.22) upon excitation in methyl alcohol at 318 nm.

Silicon PV cell production on the Moon as the basis for a new architecture for space exploration

NASA Astrophysics Data System (ADS)

Duke, Michael B.; Ignatiev, Alex; Freundlich, Alex; Rosenberg, Sanders D.; Makel, Darby

2001-02-01

A method is described by which silicon photovoltaic (PV) devices can be directly deposited onto the lunar regolith using primarily lunar materials. In sequence, a robotic ``crawler'' moving at slow speed sequentially melts the top layer of regolith and deposits a conducting layer, a doped silicon, a top conducting grid, and an antireflective coating by vacuum evaporation techniques. Concentrated solar energy is utilized as the energy source. Development of this capability would significantly lower the cost of electrical energy on the Moon and would enable a range of other activities, including lower cost propellant production, human outposts with complete food-growth capabilities, and advanced materials production. Low cost energy could affect the economics of propellants in space by allowing the extraction of solar wind hydrogen from the lunar regolith. This would allow the economical export of propellants and other materials to space, first to an Earth-Moon Lagrangian Point and potentially to low Earth orbit. .

Synthesis, spectral, thermal, optical and theoretical studies of (2E,6E)-2-benzylidene-6-(4-methoxybenzylidene)cyclohexanone.

PubMed

Meenatchi, V; Muthu, K; Rajasekar, M; Meenakshisundaram, Sp

2014-01-01

Single crystals of (2E,6E)-2-benzylidine-6-(4-methoxybenzylidine)cyclohexanone are grown by slow evaporation of ethanolic solution at room temperature. The characteristic functional groups present in the molecule are confirmed by Fourier transform infrared and Fourier transform Raman analyses. The scanning electron microscopy study reveals the surface morphology of the material. Thermogravimetric/differential thermal analysis study reveals the purity of the material and the crystal is transparent in the visible region having a lower optical cut-off at ∼487nm. The second harmonic generation efficiency of as-grown material is estimated by Kurtz and Perry technique. Optimized geometry has been derived using Hartree-Fock calculations performed at the level 6-31G (d,p) and the first-order molecular hyperpolarizability (β) is estimated. The specimen is further characterized by nuclear magnetic resonance spectroscopy. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

Bis (3-methoxy-4-hydroxybenzaldehyde-2,4,6-trinitrophenol) organic cocrystal: Synthesis and physico-chemical properties

NASA Astrophysics Data System (ADS)

Sudharsana, N.; Krishnakumar, V.; Nagalakshmi, R.

2016-10-01

A 3-methoxy-4-hydroxybenzaldehyde-2,4,6-trinitrophenol (mhba-tnp) cocrystal was grown by the slow evaporation solution growth technique using ethanol as a solvent. As-grown crystals were characterized by single crystal X-ray diffraction (XRD) study and crystallized with a centrosymmetric space group. Optical properties of the grown crystal have been studied by Ultraviolet-Visible (UV-Vis) absorption spectra in the range from 200 to 800nm and the band gap energy of the crystal was obtained as 2.8eV. Fourier transform infrared (FTIR) and micro Raman spectral analyses have been carried out to confirm the functional groups present in the title compound. Differential scanning calorimetry (DSC) and polarized light thermomicroscopy (PLTM) analyses were carried out to find the melting point. In addition, the optimized geometric parameters and the molecular orbitals were calculated using density functional theory (DFT) with the help of the Gaussian 03W software.

Enhanced optical, thermal and piezoelectric behavior in dye doped potassium acid phthalate (KAP) single crystal

NASA Astrophysics Data System (ADS)

Rao, G. Babu; Rajesh, P.; Ramasamy, P.

2017-06-01

Dye inclusion crystals have attracted researchers in the context of crystal growth for applications in solid state lasers. Pure and 0.1 mol% amaranth doped KAP single crystals, were grown from aqueous solutions by slow evaporation technique at room temperature. The grown crystals are up to the dimension of 12×10×3 mm3. Attempt is made to improve the growth rate, optical, piezoelectric and photoconductive properties of pure KAP single crystal with addition of amaranth dye as a dopant. Various characterization studies were made for both pure and dye doped KAP. Thermal stability of the crystals is tested from thermogravimetric and differential thermal analysis (TG/DTA). There is only one endothermic peak indicating decomposition point. Higher optical transparency for dye doped KAP crystal was identified from the UV-vis spectrum. Etching studies showed an improvement in the optical quality of the KAP crystal after doping with amaranth dye. The positive photoconductive nature is observed from both pure and amaranth doped KAP.

Synthesis, growth, spectral, electrical, mechanical and thermal characterization of a potential optical material: γ-glycine single crystal

NASA Astrophysics Data System (ADS)

Sivakumar, N.; Jayavel, R.; Anbalagan, G.; Yadav, R. R.

2018-06-01

Gamma glycine, an organic material was grown by slow solvent evaporation method. Conventional polythermal method was employed in the temperature range, 30-50 °C to obtain the solubility and the metastable zonewidth. The crystal and molecular structures were analyzed by X-ray powder diffraction, FT-IR and FT-Raman spectral studies. Optical refractive index was determined by prism coupling technique and was found to be 1.4488. Electrical properties such as ac conductivity and activation energy were studied for different temperatures in the frequency range from 40 Hz to 6 MHz. The dc electrical conductivity was estimated from the Cole-Cole plot and the values were found to be 2.19 × 10-6 Sm-1 at 353K and 1.46 × 10-6 Sm-1 at 373K respectively. Mechanical studies on the grown crystal revealed that the material belongs to soft materials category. Thermal conductivity and specific heat capacities were estimated by Hot Disk Thermal Constants Analyzer.

Synthesis, growth and characterization of a nonlinear optical crystal: Bis l-proline hydrogen nitrate.

PubMed

Selvaraju, K; Kirubavathi, K

2013-11-01

The single crystals of bis l-proline hydrogen nitrate (BLPHN) belonging to non-centrosymmetric space group were successfully grown by the slow evaporation solution growth technique. The BLPHN crystals of size 10×7×3mm(3) were obtained in 35days. Initially, the solubility tests were carried out for two solvents such as deionized water and mixed of deionized water-acetone. Among the two solvents, the solubility of BLPHN was found to be the highest in deionized water, so crystallization of BLPHN was done from its aqueous solution. As grown, crystals were characterized by single crystal X-ray diffraction studies and optical transmission spectral studies. Infrared spectroscopy, thermo gravimetric analysis and differential thermal analysis measurements were performed to study the molecular vibration and thermal behavior of the grown BLPHN crystals. Nonlinear optical (NLO) behavior of BLPHN crystal was studied by Kurtz and Perry powder method. Copyright © 2013 Elsevier B.V. All rights reserved.

EFFECT OF MICROWAVE SINTERING ON THE STRUCTURAL AND ELECTRICAL PROPERTIES OF Li0.51Zn0.2Ti0.2V0.01Fe2.08O4 FERRITE

NASA Astrophysics Data System (ADS)

Maisnam, Mamata; Phanjoubam, Sumitra

2013-07-01

Effect of microwave sintering on the structural and electrical properties of Li+0.51Zn2+0.2Ti4+0.2V5+0.01Fe3+2.08O2-4 is studied in comparison with that of conventionally sintered one. The technique is advantageous in terms of significantly reduced size of microwave kilns and rapid heating compared to the cumbersome and slow heating of conventional sintering technology. Microwave sintering produced enhanced densification and much finer microstructures. The DC resistivity is markedly increased. Microwave sintering reduces chances of evaporation of lithium and oxygen during sintering of lithium based ferrites resulting in formation of lesser ferrous ions. This has profound effect on the electrical properties of microwave sintered ferrites. The dielectric constant is significantly reduced possibly due to reduced space charge polarization and the temperature dependence of the dielectric properties are also studied.

Synthesis, structure and characterization of a hybrid centrosymmetric material (4-dimethylaminopyridinium nitrate gallic acid monohydrate) well-designed for non-linear optics

NASA Astrophysics Data System (ADS)

Ennaceur, Nasreddine; Jalel, Boutheina; Henchiri, Rokaya; Cordier, Marie; Ledoux-Rak, Isabelle

2018-01-01

Hybrid material: 4-Dimethylaminopyridinium nitrate gallic acid monohydrate abbreviated DNGA monohydrate has been successfully synthesized by slow evaporation method at room temperature. X-ray diffraction (XRD) on a single crystal showed that the latter was crystallized in P-1 space group. Likewise, thermal analyses demonstrated the stability of our crystal up to 80 °C. Besides, the analysis of the infrared spectrum (FTIR), allowed us to confirm the presence of the different groups present in the structure. Furthermore, by studying the UV-Visible spectrum, the transparency of our crystal was proven. Despite the fact that of having a centrosymmetric structure, the nonlinear optical properties of our single crystal, which was tested by Kurtz-Perry technique, proved that its second harmonic generation efficiency was 1.22 times more than that of KDP (potassium dihydrogen phosphate) single crystal. This nonlinear optical behavior of the studied compound was also determined through the calculations of polarizability and first hyperpolarizability values.

Effect of L-Valine on the growth and characterization of Sodium Acid Phthalate (SAP) single crystals.

PubMed

Nirmala, L Ruby; Thomas Joseph Prakash, J

2013-06-01

Undoped and amino acid doped good quality single crystals of Sodium Acid Phthalate crystals (SAP) were grown by slow evaporation solution growth technique which are semiorganic in nature. The effect of amino acid (L-Valine) dopant on the growth and the properties of SAP single crystal was investigated. The single crystal X-ray diffraction studies and FT-IR studies were carried out to identify the crystal structure and the presence of functional groups in undoped and L-Valine doped SAP crystals. The transparent nature of the grown crystal was observed using UV-Visible spectrum. The thermal decomposition of the doped SAP crystals was investigated by thermo gravimetric analysis (TGA) and differential thermal analysis (DTA). The enhancement in the NLO property of the undoped and L-Valine doped SAP crystals using KDP crystal as a reference was studied using SHG measurements. Vickers micro hardness measurements are used for the study of mechanical strength of the grown crystals. Copyright © 2013 Elsevier B.V. All rights reserved.

Growth, spectral, linear and nonlinear optical characteristics of an efficient semiorganic acentric crystal: L-valinium L-valine chloride

NASA Astrophysics Data System (ADS)

Nageshwari, M.; Jayaprakash, P.; Kumari, C. Rathika Thaya; Vinitha, G.; Caroline, M. Lydia

2017-04-01

An efficient nonlinear optical semiorganic material L-valinium L-valine chloride (LVVCl) was synthesized and grown-up by means of slow evaporation process. Single crystal XRD evince that LVVCl corresponds to monoclinic system having acentric space group P21. The diverse functional groups existing in LVVCl were discovered with FTIR spectral investigation. The UV-Visible and photoluminescence spectrum discloses the optical and electronic properties respectively for the grown crystal. Several optical properties specifically extinction coefficient, reflectance, linear refractive index, electrical and optical conductivity were also determined. The SEM analysis was also carried out and it portrayed the surface morphology of LVVCl. The calculated value of laser damage threshold was 2.59 GW/cm2. The mechanical and dielectric property of LVVCl was investigated employing microhardness and dielectric studies. The second and third order nonlinear optical characteristics of LVVCl was characterized utilizing Kurtz Perry and Z scan technique respectively clearly suggest its suitability in the domain of optics and photonics.

Habit modification of bis-thiourea zinc chloride (ZTC) semi organic crystals by impurities

NASA Astrophysics Data System (ADS)

Ruby Nirmala, L.; Thomas Joseph Prakash, J.

2013-06-01

Single crystals of bis-thiourea zinc chloride (ZTC) doped with metal ion (Li+) possess excellent nonlinear optical properties. These crystals were grown by slow evaporation solution growth technique. The effect of Li+ dopant on the growth and properties of ZTC single crystal were investigated and reported. The grown crystals were crystallized in orthorhombic structure with non-centro symmetric space group Pn21a through the parent compound. The amount of dopant incorporated in the parent crystal was revealed by the inductively coupled plasma (ICP-OES) studies. The FT-IR spectroscopy study was done for finding and confirming the functional groups present in the compound. The UV-Visible spectral study was carried out to find the optical behavior and transparency nature of the grown crystal. TG/DTA measurements and Vickers microhardness measurements were traced to find out the thermal and mechanical stability of the grown crystals respectively. Using Nd:YAG laser, the Second harmonic generation (SHG) for the grown crystals were confirmed.

Habit modification of bis-thiourea zinc chloride (ZTC) semi organic crystals by impurities.

PubMed

Ruby Nirmala, L; Thomas Joseph Prakash, J

2013-06-01

Single crystals of bis-thiourea zinc chloride (ZTC) doped with metal ion (Li(+)) possess excellent nonlinear optical properties. These crystals were grown by slow evaporation solution growth technique. The effect of Li(+) dopant on the growth and properties of ZTC single crystal were investigated and reported. The grown crystals were crystallized in orthorhombic structure with non-centro symmetric space group Pn21a through the parent compound. The amount of dopant incorporated in the parent crystal was revealed by the inductively coupled plasma (ICP-OES) studies. The FT-IR spectroscopy study was done for finding and confirming the functional groups present in the compound. The UV-Visible spectral study was carried out to find the optical behavior and transparency nature of the grown crystal. TG/DTA measurements and Vickers microhardness measurements were traced to find out the thermal and mechanical stability of the grown crystals respectively. Using Nd:YAG laser, the Second harmonic generation (SHG) for the grown crystals were confirmed. Copyright © 2013 Elsevier B.V. All rights reserved.

Synthesis and structural study of 4-(2-chlorophenyl)-2-ethoxy-5,6,7,8,9,10-hexahydrocycloocta[B] pyridine-3-carbonitrile

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

Fathima, K. Saiadali; Vasumathi, M.; Anitha, K., E-mail: singlecrystalxrd@gmail.com

2016-05-23

The novel organic material C{sub 20}H{sub 21}ClN{sub 2}O was synthesized by One-Pot synthesis method and the single crystals were grown by slow evaporation solution growth technique. The crystal structure was elucidated by subjecting the grown crystals to the single crystal x-ray diffraction analysis and was refined by full matrix least-squares method to R=0.039 for 2746 reflections. Crystal system of the grown crystal was found to be monoclinic with the space group P2{sub 1}/a and a=9.196(4) Å, b=13.449(4) Å, c=14.818(4) Å, β= 101.542(3)°, V=1795.6(11) Å{sup 3} and Z=4. In this crystal structure, cyclooctanone prefers to reside in a chair-boat conformation. Themore » structure is stabilized by attractive molecular force such as CH/π interaction called hydrophobic interaction.« less

Synthesis of a novel methyl(2E)-2-{[N-(2-formylphenyl)(4-methylbenzene) sulfonamido]methyl}-3-(2-methoxyphenyl)prop-2-enoate: Molecular structure, spectral, antimicrobial, molecular docking and DFT computational approaches

NASA Astrophysics Data System (ADS)

Murugavel, S.; Vetri velan, V.; Kannan, Damodharan; Bakthadoss, Manickam

2017-01-01

The title compound methyl(2E)-2-{[N-(2-formylphenyl)(4-methylbenzene)sulfonamido] methyl}-3-(2-methoxyphenyl)prop-2-enoate (MFMSM) has been synthesized and single crystals were grown by slow evaporation solution growth technique at room temperature. XRD, FT-IR and NMR spectra of MFMSM in the solid phase were recorded and analyzed. The optimized geometry and vibrational wave numbers were computed using DFT method. The NLO, Mulliken, MEP, HOMO-LUMO energy gap and thermodynamic properties were theoretically predicted. The NBO analysis explained the intramolecular hydrogen bonding. The global chemical reactivity descriptors are calculated for MFMSM and used to predict their relative stability and reactivity. All the calculations were carried out by B3LYP/6-311G (d,p) method. MFMSM has been screened for its antimicrobial activity and found to exhibit antifungal and antibacterial effects. Docking simulation has been performed.

Experimental and theoretical analysis of a rare nitrato bridged 3d-4f complex containing LaZn2 core synthesized from a Zn(II) metalloligand

NASA Astrophysics Data System (ADS)

Sreejith, S. S.; Mohan, Nithya; Kurup, M. R. Prathapachandra

2018-02-01

A trinulcear Zn2La Schiff base complex was synthesized using slow-solvent evaporation technique from a Zn(II) mononuclear metalloligand by 2:1 addition with La(NO3)3 salt. Single crystal XRD analysis revealed a rare nitrato bridged trinuclear entity which is seldom seen in these class of ligand systems. Qualitative and quantitative analysis of intermolecular interactions/short contacts were done using Hirshfeld surface and 2D finger print analysis. The thermally stable, blue luminescent compound exhibits internal heavy atom effect thereby quenching the emission intensity of the ligand. DFT calculations were performed on the compound to analyze frontier orbitals and also ESP plots were used to monitor nucleophilic/electrophilic regions on the compound and its implications on hydrogen bonding. A comparison of the bond orders and atomic charges on the trinuclear compound and the Zn(II) metalloligand precursor was performed to substantiate the formation of the trinuclear product through ligand exchange.

Comparison of techniques for estimating annual lake evaporation using climatological data

USGS Publications Warehouse

Andersen, M.E.; Jobson, H.E.

1982-01-01

Mean annual evaporation estimates were determined for 30 lakes by use of a numerical model (Morton, 1979) and by use of an evaporation map prepared by the U.S. Weather Service (Kohler et al., 1959). These estimates were compared to the reported value of evaporation determined from measurements on each lake. Various lengths of observation and methods of measurement were used among the 30 lakes. The evaporation map provides annual evaporation estimates which are more consistent with observations than those determined by use of the numerical model. The map cannot provide monthly estimates, however, and is only available for the contiguous United States. The numerical model can provide monthly estimates for shallow lakes and is based on monthly observations of temperature, humidity, and sunshine duration.

The interaction of Dirac particles with a Hawking charged radiating black hole

NASA Astrophysics Data System (ADS)

Kubik, Erik

2007-08-01

The interaction of spin 1/2 fields with a charged, evaporating black hole (EBH) is investigated. Using the Vaidya metric to model the Hawking evaporating black hole, the wave equation for a massless spinor field is obtained. The resulting field equation is solved utilizing techniques developed by Brill and Wheeler. Unlike previous efforts, a charged, evaporating black hole has never been used as a background to investigate spin 1/2 quantum field propagation, e.g., Brill and Wheeler considered massless spin 1/2 interactions in a static, Schwarzschild background. Using the WKB approximation, the wave equation is solved for the case of an EBH with constant luminosity. Analysis of the effective potential at different stages of evaporation is made including the dependence on the parameters of the system such as the total angular momentum, energy of the incident field, and luminosity of the evaporating black hole. Utilizing techniques of Mukhopad-hey, the transmission and reflection coefficients for the massless spinors are computed and compared to Schwarzschild result for both the high energy and hard scattering cases. The effect of the time dependence of the space-time metric has an important effect on the behavior of quantum fields over the lifetime of the evaporating black hole and may provide a signature for the detection of such objects.

Effect of Nd:YAG laser on the solvent evaporation of adhesive systems.

PubMed

Batista, Graziela Ribeiro; Barcellos, Daphne Câmara; Rocha Gomes Torres, Carlos; Damião, Álvaro José; de Oliveira, Hueder Paulo Moisés; de Paiva Gonçalves, Sérgio Eduardo

2015-01-01

This study evaluated the influence of Nd:YAG laser on the evaporation degree (ED) of the solvent components in total-etch and self-etch adhesives. The ED of Gluma Comfort Bond (Heraeus-Kulzer) one-step self-etch adhesive, and Adper Single Bond 2 (3M ESPE), and XP Bond (Dentsply) total-etch adhesives was determined by weight alterations using two techniques: Control--spontaneous evaporation of the solvent for 5 min; Experimental--Nd:YAG laser irradiation for 1 min, followed by spontaneous evaporation for 4 min. The weight loss due to evaporation of the volatile components was measured at baseline and after 10 s, 20 s, 30 s, 40 s, 50 s, 60 s, 70 s, 80 s, 90 s, 100 s, 110 s, 2 min, 3 min, 4 min, and 5 min. Evaporation of solvent components significantly increased with Nd:YAG laser irradiation for all adhesives investigated. Gluma Comfort Bond showed significantly higher evaporation of solvent components than Adper Single Bond 2 and XP Bond. All the adhesives lost weight quickly during the first min of Nd:YAG laser irradiation. The application of Nd:YAG laser on adhesives before light curing had a significant effect on the evaporation of the solvent components, and the ED of Gluma Comfort Bond one-step self-etch adhesive was significantly higher than with Adper Single Bond 2 and XP Bond total-etch adhesives. The use of the Nd:YAG laser on the uncured adhesive technique can promote a greater ED of solvents, optimizing the longevity of the adhesive restorations.

Ion plating for the future

NASA Technical Reports Server (NTRS)

Spalvins, T.

1981-01-01

The ion plating techniques are classified relative to the instrumental set up, evaporation media, and mode of transport. A distinction is drawn between the low vacuum (plasma) and high vacuum (ion beam) techniques. Ion plating technology is discussed at the fundamental and industrial level. At the fundamental level, the capabilities and limitations of the plasma (evaporant flux) and film characteristics are evaluated. And on the industrial level, the performance and potential uses of ion plated films are discussed.

Ion plating for the future

NASA Technical Reports Server (NTRS)

Spalvins, T.

1981-01-01

The ion plating techniques are classified relative to the instrumental set up, evaporation media and mode of transport. Distinction is drawn between the low vacuum (plasma) and high vacuum (ion beam) techniques. Ion plating technology is discussed at the fundamental and industrial level. At the fundamental level, the capabilities and limitations of the plasma (evaporant flux) and film characteristics are evaluated. On the industrial level, the performance and potential uses of ion plated films are discussed.

Fabrication of Josephson Junction without shadow evaporation

NASA Astrophysics Data System (ADS)

Wu, Xian; Ku, Hsiangsheng; Long, Junling; Pappas, David

We developed a new method of fabricating Josephson Junction (Al/AlOX/Al) without shadow evaporation. Statistics from room temperature junction resistance and measurement of qubits are presented. Unlike the traditional ``Dolan Bridge'' technique, this method requires two individual lithographies and straight evaporations of Al. Argon RF plasma is used to remove native AlOX after the first evaporation, followed by oxidation and second Al evaporation. Junction resistance measured at room temperature shows linear dependence on Pox (oxidation pressure), √{tox} (oxidation time), and inverse proportional to junction area. We have seen 100% yield of qubits made with this method. This method is promising because it eliminates angle dependence during Junction fabrication, facilitates large scale qubits fabrication.

[Dynamics of Irreversible Evaporation of a Water-Protein Droplet and a Problem of Structural and Dynamical Experiments with Single Molecules].

PubMed

Shaitan, K V; Armeev, G A; Shaytan, A K

2016-01-01

We discuss the effect of isothermal and adiabatic evaporation of water on the state of a water-protein droplet. The discussed problem is of current importance due to development of techniques to perform single molecule experiments using free electron lasers. In such structure-dynamic experiments the delivery of a sample into the X-ray beam is performed using the microdroplet injector. The time between the injection and delivery is in the order of microseconds. In this paper we developed a specialized variant of all-atom molecular dynamics simulations for the study of irreversible isothermal evaporation of the droplet. Using in silico experiments we determined the parameters of isothermal evaporation of the water-protein droplet with the sodium and chloride ions in the concentration range of 0.3 M at different temperatures. The energy of irreversible evaporation determined from in silico experiments at the initial stages of evaporation virtually coincides with the specific heat of evaporation for water. For the kinetics of irreversible adiabatic evaporation an exact analytical solution was obtained in the limit of high thermal conductivity of the droplet (or up to the droplet size of -100 Å). This analytical solution incorporates parameters that are determined using in silico. experiments on isothermal droplet evaporation. We show that the kinetics of adiabatic evaporation and cooling of the droplet scales with the droplet size. Our estimates of the water-protemi droplet. freezing rate in the adiabatic regime in a vacuum chamber show that additional techniques for stabilizing the temperature inside the droplet should be used in order to study the conformational transitions of the protein in single molecules. Isothermal and quasi-isothermal conditions are most suitable for studying the conformational transitions upon object functioning. However, in this case it is necessary to take into account the effects of dehydration and rapid increase of ionic strength in an aqueous microenvironment surrounding the protein.

Chemical and isotopic fractionations by evaporation and their cosmochemical implications

NASA Astrophysics Data System (ADS)

Ozawa, Kazuhito; Nagahara, Hiroko

2001-07-01

A kinetic model for evaporation of a multi-component condensed phase with a fixed rate constant of the reaction is developed. A binary system with two isotopes for one of the components undergoing simple thermal histories (e.g., isothermal heating) is investigated in order to evaluate the extent of isotopic and chemical fractionations during evaporation. Diffusion in the condensed phase and the effect of back reaction from ambient gas are taken into consideration. Chemical and isotopic fractionation factors and the Péclet number for evaporation are the three main parameters that control the fractionation. Dust enrichment factor (η), the ratio of the initial dust quantity to that required for attainment of gas-dust equilibrium, is critical when back reactions become significant. Dust does not reach equilibrium with gas at η < 1. Notable chemical and isotopic fractionations usually take place under these conditions. There are two circumstances in which isotopic fractionation of a very volatile element does not accompany chemical fractionation during isothermal heating. One is free evaporation when diffusion in the condensed phase is very slow (η = 0), and the other is evaporation in the presence of ambient gas (η > 0). In the former case, a quasi-steady state in the diffusion boundary layer is maintained for isotopic fractionation but not for chemical fractionation. In the latter case, the back reaction brings the strong isotopic fractionation generated in the earlier stage of evaporation back to a negligibly small value in the later stage before complete evaporation. The model results are applied to cosmochemical fractionation of volatile elements during evaporation from a condensed phase that can be regarded as a binary solution phase. The wide range of potassium depletion without isotopic fractionation in various types of chondrules (Alexander et al., 2000) is explained by instantaneous heating followed by cooling in a closed system with various degrees of dust enrichment (η = 0.001-10) and cooling rates of less than ˜5°C/min. The extent of decoupling between isotopic and chemical fractionations of various elements in chondrules and matrix minerals may constrain the time scale and the conditions of heating and cooling processes in the early solar nebula.

Microstructure and phase composition of hypoeutectic Te-Bi alloy as evaporation source for photoelectric cathode

NASA Astrophysics Data System (ADS)

Wang, Bao-guang; Yang, Wen-hui; Gao, Hong-ye; Tian, Wen-huai

2018-05-01

A hypoeutectic 60Te-40Bi alloy in mass percent was designed as a tellurium atom evaporation source instead of pure tellurium for an ultraviolet detection photocathode. The alloy was prepared by slow solidification at about 10-2 K·s-1. The microstructure, crystal structure, chemical composition, and crystallographic orientation of each phase in the as-prepared alloy were investigated by optical microscopy, scanning electron microscopy, X-ray diffraction, electron backscatter diffraction, and transmission electron microscopy. The experimental results suggest that the as-prepared 60Te-40Bi alloy consists of primary Bi2Te3 and eutectic Bi2Te3/Te phases. The primary Bi2Te3 phase has the characteristics of faceted growth. The eutectic Bi2Te3 phase is encased by the eutectic Te phase in the eutectic structure. The purity of the eutectic Te phase reaches 100wt% owing to the slow solidification. In the eutectic phases, the crystallographic orientation relationship between Bi2Te3 and Te is confirmed as {[0001]_{B{i_2}T{e_3}}}//{[1\\bar 21\\bar 3]_{Te}} and the direction of Te phase parallel to {[11\\bar 20]_{B{i_2}T{e_3}}} is deviated by 18° from Te N{(2\\bar 1\\bar 11)_{Te}}.

A multiple ion counter total evaporation (MICTE) method for precise analysis of plutonium by thermal ionization mass spectrometry

DOE PAGES

Inglis, Jeremy D.; Maassen, Joel; Kara, Azim; ...

2017-04-28

This study presents a total evaporation method for the analysis of sub-picogram quantities of Pu, utilizing an array of multiple ion counters. Data from three standards are presented to assess the utility of the technique. An external precision of 1.5% RSD (2σ) was achieved on aliquots approaching 100 fg for the minor 240Pu isotope. Accurate analysis of <1 femtogram of 240Pu, is achievable, with an external reproducibility of better than 10% RSD (2σ). Finally, this new technique represents a significant advance in the total evaporation method and will allow routine measurement of femtogram sized Pu samples by thermal ionization massmore » spectrometry.« less

A multiple ion counter total evaporation (MICTE) method for precise analysis of plutonium by thermal ionization mass spectrometry

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

Inglis, Jeremy D.; Maassen, Joel; Kara, Azim

This study presents a total evaporation method for the analysis of sub-picogram quantities of Pu, utilizing an array of multiple ion counters. Data from three standards are presented to assess the utility of the technique. An external precision of 1.5% RSD (2σ) was achieved on aliquots approaching 100 fg for the minor 240Pu isotope. Accurate analysis of <1 femtogram of 240Pu, is achievable, with an external reproducibility of better than 10% RSD (2σ). Finally, this new technique represents a significant advance in the total evaporation method and will allow routine measurement of femtogram sized Pu samples by thermal ionization massmore » spectrometry.« less

Fast Assembly of Gold Nanoparticles in Large-Area 2D Nanogrids Using a One-Step, Near-Infrared Radiation-Assisted Evaporation Process.

PubMed

Utgenannt, André; Maspero, Ross; Fortini, Andrea; Turner, Rebecca; Florescu, Marian; Jeynes, Christopher; Kanaras, Antonios G; Muskens, Otto L; Sear, Richard P; Keddie, Joseph L

2016-02-23

When fabricating photonic crystals from suspensions in volatile liquids using the horizontal deposition method, the conventional approach is to evaporate slowly to increase the time for particles to settle in an ordered, periodic close-packed structure. Here, we show that the greatest ordering of 10 nm aqueous gold nanoparticles (AuNPs) in a template of larger spherical polymer particles (mean diameter of 338 nm) is achieved with very fast water evaporation rates obtained with near-infrared radiative heating. Fabrication of arrays over areas of a few cm(2) takes only 7 min. The assembly process requires that the evaporation rate is fast relative to the particles' Brownian diffusion. Then a two-dimensional colloidal crystal forms at the falling surface, which acts as a sieve through which the AuNPs pass, according to our Langevin dynamics computer simulations. With sufficiently fast evaporation rates, we create a hybrid structure consisting of a two-dimensional AuNP nanoarray (or "nanogrid") on top of a three-dimensional polymer opal. The process is simple, fast, and one-step. The interplay between the optical response of the plasmonic Au nanoarray and the microstructuring of the photonic opal results in unusual optical spectra with two extinction peaks, which are analyzed via finite-difference time-domain method simulations. Comparison between experimental and modeling results reveals a strong interplay of plasmonic modes and collective photonic effects, including the formation of a high-order stopband and slow-light-enhanced plasmonic absorption. The structures, and hence their optical signatures, are tuned by adjusting the evaporation rate via the infrared power density.

Pinning-Depinning Mechanisms of the Contact Line during Evaporation of Microdroplets on Rough Surfaces: A Lattice Boltzmann Simulation.

PubMed

Yuan, Wu-Zhi; Zhang, Li-Zhi

2018-06-22

In this study, pinning and depinning of the contact line during droplet evaporation on the rough surfaces with randomly distributed structures is theoretically analyzed and numerically investigated. A fast Fourier transformation (FFT) method is used to generate the rough surfaces, whose skewness ( Sk), kurtosis ( K), and root-mean-square ( Rq) are obtained from real surfaces. A thermal multiphase LB model is proposed to simulate the isothermal pinning and depinning processes. The evaporation processes are recorded with the variations in contact angle, contact radius, and drop shape. It is found that the drops sitting on rough surfaces show different behavior from those on smoother surfaces. The former shows a pinned contact line during almost the whole lifetime. By contrast, the latter experiences a stick-slip-jump behavior until the drop disappears. At mesoscopic scale, the pinning of the contact line is actually a slow motion rather than a complete immobilization at the sharp edges. The dynamic equilibrium is achieved by the self-adjustment of the contact line according to each edge.

Investigation of Capillary Limit in a Loop Heat Pipe

NASA Technical Reports Server (NTRS)

Ku, Jentung; Ottenstein, Laura; Rogers, Paul; Cheung, Kwok; Obenschain, Arthur F. (Technical Monitor)

2001-01-01

This paper presets an experimental study on the capillary limit of a loop heat pipe (LHP) at low powers. The slow thermal response of the loop at low powers made it possible to observe interactions among various components after the capillary limit was exceeded. The capillary limit at low powers was achieved by imposing additional pressure drops on the vapor line through the use of a metering valve. A differential pressure transducer was also used to measure the pressure drop across the evaporator and the compensation chamber (CC). Test results show that when the capillary limit is exceeded, vapor will penetrate the primary wick, resulting in a partial dry-out of the evaporator and a rapid increase of the CC temperature. Because the evaporator can tolerate vapor bubbles, the LHP will continue to function and may reach a new steady state at the higher temperature. Thus, the LHP will exhibit a graceful degradation in performance rather than a complete failure. Moreover, the loop can recover from a partial dry-out by reducing the heat load without a re-start.

Convection effects in protein crystal growth

NASA Technical Reports Server (NTRS)

Roberts, Glyn O.

1988-01-01

Protein crystals for X-ray diffraction study are usually grown resting on the bottom of a hanging drop of a saturated protein solution, with slow evaporation to the air in a small enclosed cell. The evaporation rate is controlled by hanging the drop above a reservoir of water, with its saturation vapor pressure decreased by a low concentration of a passive solute. The drop has a lower solute concentration, and its volume shrinks by evaporation until the molecular concentrations match. Protein crystals can also be grown from a seed crystal suspended or supported in the interior of a supersaturated solution. The main analysis of this report concerns this case because it is less complicated than hanging-drop growth. Convection effects have been suggested as the reason for the apparent cessation of growth at a certain rather small crystal size. It seeems that as the crystal grows, the number of dislocations increases to a point where further growth is hindered. Growth in the microgravity environment of an orbiting space vehicle has been proposed as a method for obtaining larger crystals. Experimental observations of convection effects during the growth of protein crystals have been reported.

Determination of particulate lead during MILAGRO / MCMA-2006 using Aerosol Mass Spectrometry

NASA Astrophysics Data System (ADS)

Salcedo, Dara; Onasch, T. B.; Aiken, A. C.; Williams, L. R.; de Foy, B.; Cubison, M. J.; Worsnop, D. R.; Molina, L. T.; Jimenez, J. L.

2010-05-01

We report the first measurements of particulate lead (Pb) from Aerodyne Aerosol Mass Spectrometers, which were deployed in and around Mexico City during the Megacity Initiative: Local and Global Research Observations (MILAGRO) / Mexico City Metropolitan Area 2006 (MCMA-2006) field campaigns. The high resolution mass spectrometer of one of the AMS instruments (HR-AMS) and the measured isotopic ratios unequivocally prove the detection of Pb in ambient particles. A substantial fraction of the lead evaporated slowly from the vaporizer of the instruments, which is indicative of species with low volatility at 600oC. A model was developed in order to estimate the ambient particulate Pb entering the AMS from the signals in the "open" and the "closed" (or "background") mass spectrum modes of the AMS. The model suggests the presence of at least two lead fractions with ~25% of the Pb signal exhibiting rapid evaporation (1/e decay constant, τ < 0.1 s) and ~75% exhibiting slow evaporation (τ ~2.4 min) at T0 and a different fraction (70% prompt and 30% slow evaporation) at a site northwest from the metropolitan area (PEMEX32 site). From laboratory experiments with pure Pb(NO3)2 particles, we estimated that the Pb ionization efficiency relative to nitrate (RIEPb) is 0.5. Comparison of time series of AMS Pb with other measurements carried out at the T0 urban supersite during MILAGRO (using Proton Induced X-ray Emission (PIXE), Inductively-Coupled Plasma Mass Spectrometry (ICP-MS) and single-particle counts from an Aerosol Time-of-Fight Mass Spectrometer (ATOFMS)) shows similar levels (for PIXE and ICP-MS) and substantial correlation. During part of the campaign, sampling at T0 was alternated every 10 minutes with an Aerosol Concentrator, which enabled the detection of signals for PbCl+ and PbS+ ions. PbS+ displays the signature of a slowly evaporating species, while PbCl+ appears to arise only from fast evaporation, which is likely due to the higher vapor pressure of the compounds generating PbCl+. This is consistent with the evaporation model results. Levels of particulate Pb measured during MILAGRO at T0 were similar to previous studies in Mexico City. Pb shows a diurnal cycle with a maximum in the early morning, which is typical of primary urban pollutants. Pb shows correlation with Zn, consistent with previous studies, while the sources of Pb appear to be at least partially disjoint from those of particulate chloride. Back trajectory analysis of the T0 Pb data suggests the presence of sources inside the urban area SSW and N of T0, with different chemical forms of Pb being associated with different source locations. High signals due to particulate lead were also detected in the PEMEX site; again, no correlation between Pb and chloride plumes was observed, suggesting mostly different sources for both species.

Determination of particulate lead during MILAGRO/MCMA-2006 using Aerosol Mass Spectrometry

NASA Astrophysics Data System (ADS)

Salcedo, D.; Onasch, T. B.; Aiken, A. C.; Williams, L. R.; de Foy, B.; Cubison, M. J.; Worsnop, D. R.; Molina, L. T.; Jimenez, J. L.

2010-02-01

We report the first measurements of particulate lead (Pb) from Aerodyne Aerosol Mass Spectrometers, which were deployed in and around Mexico City during the Megacity Initiative: Local and Global Research Observations (MILAGRO)/Mexico City Metropolitan Area 2006 (MCMA-2006) field campaigns. The high resolution mass spectrometer of one of the AMS instruments (HR-AMS) and the measured isotopic ratios unequivocally prove the detection of Pb in ambient particles. A substantial fraction of the lead evaporated slowly from the vaporizer of the instruments, which is indicative of species with low volatility at 600 °C. A model was developed in order to estimate the ambient particulate Pb entering the AMS from the signals in the "open" and the "closed" (or "background") mass spectrum modes of the AMS. The model suggests the presence of at least two lead fractions with ~25% of the Pb signal exhibiting rapid evaporation (1/e decay constant, τ<0.1 s) and ~75% exhibiting slow evaporation (τ~2.4 min) at the T0 urban supersite and a different fraction (70% prompt and 30% slow evaporation) at a site northwest from the metropolitan area (PEMEX site). From laboratory experiments with pure Pb(NO3)2 particles, we estimated that the Pb ionization efficiency relative to nitrate (RIEPb) is 0.5. Comparison of time series of AMS Pb with other measurements carried out at T0 (using Proton Induced X-ray Emission (PIXE), Inductively-Coupled Plasma Mass Spectrometry (ICP-MS) and single-particle counts from an Aerosol Time-of-Fight Mass Spectrometer (ATOFMS)) shows similar levels (for PIXE and ICP-MS) and substantial correlation. During part of the campaign, sampling at T0 was alternated every 10 min with an Aerosol Concentrator, which enabled the detection of signals for PbCl+ and PbS+ ions. PbS+ displays the signature of a slowly evaporating species, while PbCl+ appears to arise only from fast evaporation, which is likely due to the higher vapor pressure of the compounds generating PbCl+. This is consistent with the evaporation model results. Levels of particulate Pb measured at T0 were similar to previous studies in Mexico City. Pb shows a diurnal cycle with a maximum in the early morning, which is typical of primary urban pollutants. Pb shows correlation with Zn, consistent with previous studies, while the sources of Pb appear to be at least partially disjoint from those of particulate chloride. Back trajectory analysis of the T0 Pb data suggests the presence of sources inside the urban area SSW and N of T0, with different chemical forms of Pb being associated with different source locations. High signals due to particulate lead were also detected in the PEMEX site; again, no correlation between Pb and chloride plumes was observed, suggesting mostly different sources for both species.

Determination of particulate lead using aerosol mass spectrometry: MILAGRO/MCMA-2006 observations

NASA Astrophysics Data System (ADS)

Salcedo, D.; Onasch, T. B.; Aiken, A. C.; Williams, L. R.; de Foy, B.; Cubison, M. J.; Worsnop, D. R.; Molina, L. T.; Jimenez, J. L.

2010-06-01

We report the first measurements of particulate lead (Pb) from Aerodyne Aerosol Mass Spectrometers, which were deployed in and around Mexico City during the Megacity Initiative: Local and Global Research Observations (MILAGRO)/Mexico City Metropolitan Area 2006 (MCMA-2006) field campaigns. The high resolution mass spectrometer of one of the AMS instruments (HR-AMS) and the measured isotopic ratios unequivocally prove the detection of Pb in ambient particles. A substantial fraction of the lead evaporated slowly from the vaporizer of the instruments, which is indicative of species with low volatility at 600 °C. A model was developed in order to estimate the ambient particulate Pb entering the AMS from the signals in the "open" and the "closed" (or "background") mass spectrum modes of the AMS. The model suggests the presence of at least two lead fractions with ~25% of the Pb signal exhibiting rapid evaporation (1/e decay constant, τ<0.1 s) and ~75% exhibiting slow evaporation (τ~2.4 min) at the T0 urban supersite and a different fraction (70% prompt and 30% slow evaporation) at a site northwest from the metropolitan area (PEMEX site). From laboratory experiments with pure Pb(NO3)2 particles, we estimated that the Pb ionization efficiency relative to nitrate (RIEPb) is 0.5. Comparison of time series of AMS Pb with other measurements carried out at the T0 supersite during MILAGRO (using Proton Induced X-ray Emission (PIXE), Inductively-Coupled Plasma Mass Spectrometry (ICP-MS) and single-particle counts from an Aerosol Time-of-Fight Mass Spectrometer (ATOFMS)) shows similar levels (for PIXE and ICP-MS) and substantial correlation. During part of the campaign, sampling at T0 was alternated every 10 min with an Aerosol Concentrator, which enabled the detection of signals for PbCl+ and PbS+ ions. PbS+ displays the signature of a slowly evaporating species, while PbCl+ appears to arise only from fast evaporation, which is likely due to the higher vapor pressure of the compounds generating PbCl+. This is consistent with the evaporation model results. Levels of particulate Pb measured at T0 were similar to previous studies in Mexico City. Pb shows a diurnal cycle with a maximum in the early morning, which is typical of primary urban pollutants. Pb shows correlation with Zn, consistent with previous studies, while the sources of Pb appear to be at least partially disjoint from those of particulate chloride. Back trajectory analysis of the T0 Pb data suggests the presence of sources inside the urban area SSW and N of T0, with different chemical forms of Pb being associated with different source locations. High signals due to particulate lead were also detected in the PEMEX site; again, no correlation between Pb and chloride plumes was observed, suggesting mostly different sources for both species.

Seedless Growth of Bismuth Nanowire Array via Vacuum Thermal Evaporation

PubMed Central

Liu, Mingzhao; Nam, Chang-Yong; Zhang, Lihua

2015-01-01

Here a seedless and template-free technique is demonstrated to scalably grow bismuth nanowires, through thermal evaporation in high vacuum at RT. Conventionally reserved for the fabrication of metal thin films, thermal evaporation deposits bismuth into an array of vertical single crystalline nanowires over a flat thin film of vanadium held at RT, which is freshly deposited by magnetron sputtering or thermal evaporation. By controlling the temperature of the growth substrate the length and width of the nanowires can be tuned over a wide range. Responsible for this novel technique is a previously unknown nanowire growth mechanism that roots in the mild porosity of the vanadium thin film. Infiltrated into the vanadium pores, the bismuth domains (~ 1 nm) carry excessive surface energy that suppresses their melting point and continuously expels them out of the vanadium matrix to form nanowires. This discovery demonstrates the feasibility of scalable vapor phase synthesis of high purity nanomaterials without using any catalysts. PMID:26709727

Open-tube diffusion techniques for InP/LnGaAs heterojunctior bipolar transistors

NASA Astrophysics Data System (ADS)

Schuitemaker, P.; Houston, P. A.

1986-11-01

Open-tube diffusion techniques used between 450 and 600° C are described which involve the supply of diffusant from a vapour source (via a solution) and a solid evaporated metal source. Investigations of Zn into InP and InGaAs(P) have been undertaken using both sources. SIMS profile analyses show that in the case of the vapour source the profiles indicate a concentration-dependent diffusion coefficient while the solid source diffusions can be well described by a Gaussian-type profile. The usefulness of the vapour source method has been demonstrated in the fabrication of bipolar transistors which exhibit good d.c. characteristics. The solid source method is limited by the slow diffusion velocity and more gradual profile. The InGaAs(P)/InP materials system has important applications in optical communications and future high speed microwave and switching devices. Useful technologies allied to the introduction of impurities into Si by diffusion, have gradually been emerging for use in the III-V semiconductor family. Closed tube systems1 have been used in order to contain the volatile group V species and prevent surface erosion. In addition, simpler open tube systems2,3 have been developed that maintain a sufficient overpressure of the group V element. Zn and Cd p-dopants have been studied extensively because of the volatility and relatively large diffusion rates in III-V semiconductors. Opentube diffusion into both InP and InGaAs2-6 has been studied but little detail has appeared concerning InGaAs and InGaAsP. In this paper we describe a comprehensive study of the diffusion of Zn into InP and InGaAs(P) using both open-tube vapour source and a Au/Zn/Au evaporated solid source with SiNx acting both as a mask and also an encapsulant to prevent loss of Zn and decomposition of the substrate material. The techniques have been successfully applied to the fabrication of InP/lnGaAs heterojunction bipolar transistors which show good dc characteristics. Reference to InGaAs in the text implies the InP lattice-matched composition In0.53Ga0.47As.

Evaporation from weighing precipitation gauges: impacts on automated gauge measurements and quality assurance methods

NASA Astrophysics Data System (ADS)

Leeper, R. D.; Kochendorfer, J.

2014-12-01

The effects of evaporation on precipitation measurements have been understood to bias total precipitation lower. For automated weighing-bucket gauges, the World Meteorological Organization (WMO) suggests the use of evaporative suppressants with frequent observations. However, the use of evaporation suppressants is not always feasible due to environmental hazards and the added cost of maintenance, transport, and disposal of the gauge additive. In addition, research has suggested that evaporation prior to precipitation may affect precipitation measurements from auto-recording gauges operating at sub-hourly frequencies. For further evaluation, a field campaign was conducted to monitor evaporation and its impacts on the quality of precipitation measurements from gauges used at US Climate Reference Network (USCRN) stations. Collocated Geonor gauges with (nonEvap) and without (evap) an evaporative suppressant were compared to evaluate evaporative losses and evaporation biases on precipitation measurements. From June to August, evaporative losses from the evap gauge exceeded accumulated precipitation, with an average loss of 0.12 mm h-1. However, the impact of evaporation on precipitation measurements was sensitive to calculation methods. In general, methods that utilized a longer time series to smooth out sensor noise were more sensitive to gauge (-4.6% bias with respect to control) evaporation than methods computing depth change without smoothing (< +1% bias). These results indicate that while climate and gauge design affect gauge evaporation rates computational methods can influence the magnitude of evaporation bias on precipitation measurements. It is hoped this study will advance QA techniques that mitigate the impact of evaporation biases on precipitation measurements from other automated networks.

Factors controlling the evaporation of secondary organic aerosol from α‐pinene ozonolysis

PubMed Central

Pajunoja, Aki; Tikkanen, Olli‐Pekka; Buchholz, Angela; Faiola, Celia; Väisänen, Olli; Hao, Liqing; Kari, Eetu; Peräkylä, Otso; Garmash, Olga; Shiraiwa, Manabu; Ehn, Mikael; Lehtinen, Kari; Virtanen, Annele

2017-01-01

Abstract Secondary organic aerosols (SOA) forms a major fraction of organic aerosols in the atmosphere. Knowledge of SOA properties that affect their dynamics in the atmosphere is needed for improving climate models. By combining experimental and modeling techniques, we investigated the factors controlling SOA evaporation under different humidity conditions. Our experiments support the conclusion of particle phase diffusivity limiting the evaporation under dry conditions. Viscosity of particles at dry conditions was estimated to increase several orders of magnitude during evaporation, up to 109 Pa s. However, at atmospherically relevant relative humidity and time scales, our results show that diffusion limitations may have a minor effect on evaporation of the studied α‐pinene SOA particles. Based on previous studies and our model simulations, we suggest that, in warm environments dominated by biogenic emissions, the major uncertainty in models describing the SOA particle evaporation is related to the volatility of SOA constituents. PMID:28503004

Crystallization of proteins by dynamic control of supersaturation. Ph.D. Thesis Semiannual Status Report, 21 Mar. - 20 Sep. 1990

NASA Technical Reports Server (NTRS)

Wilson, Lori June

1990-01-01

The growth of protein crystals is known to be the limiting factor in the determination of the three-dimensional structures of most proteins. It is expected that the kinetics of supersaturation, which is directly related to solvent evaporation, will affect protein crystal growth and nucleation and accordingly determine the quality, number, size, and morphology of the crystals. With a technique that controls the evaporation of solvent from a protein solution with N2(g) it is possible to determine the effect of different evaporation profiles on hen egg white lysozyme crystals. Hen egg white lysozyme was chosen as the model protein because it crystallizes easily and has solubility data available for most salt, pH, and temperature ranges. Commercially available lysozyme was further purified by a number of methods. Crystals grown with the purified lysozyme and with the unpurified lysozyme in citrate buffer were different shapes but were found to be of the same symmetry space group by precession photos. Differences were seen in the lysozyme crystals grown using different evaporation rates. At three of the four initial conditions for lysozyme crystal growth, longer evaporation times yielded better crystals. The evaporation times required to see a change in the appearance of the crystals was much longer than expected. The number of rates studied so far represent only a small fraction of the ones now available with the gas evaporation device. The technique also provides for control of both solution pH and temperature which are related to the solubilities of proteins.

Microfluidic evaporator for on-chip sample concentration.

PubMed

Casadevall i Solvas, Xavier; Turek, Vladimir; Prodromakis, Themistoklis; Edel, Joshua B

2012-10-21

We present a simple technique for the concentration of liquid samples in microfluidic devices applicable for single or multiple-phase configurations. The strategy consists of capturing the sample of interest within microfluidic traps and breaking its continuity by the introduction of a gas phase, which is also used to evaporate it.

A study of the initial oxidation of evaporated thin films of aluminum by AES, ELS, and ESD

NASA Technical Reports Server (NTRS)

Bujor, M.; Larson, L. A.; Poppa, H.

1982-01-01

The room temperature, low pressure, oxidation of evaporated aluminum thin films has been studied by AES, ELS, and ESD. ESD was the most sensitive of the three methods to characterize a clean aluminum surface. Two oxidation stages were distinguished in the 0-3000 L oxygen exposure range. Between 0 and 50 L, the chemisorption of oxygen atoms was characterized by a fast decrease of the 67 eV AES Al peak and the 10 eV surface plasmon peak, and by a simultaneous increase of the oxygen AES and ESD signals. After 50 L, a change in slope in all AES and ESD signal variations was attributed to the slow growth of a thin layer of aluminum oxide, which after 3000 L was still only a few angstroms thick.

Study of Evaporation Rate of Water in Hydrophobic Confinement using Forward Flux Sampling

NASA Astrophysics Data System (ADS)

Sharma, Sumit; Debenedetti, Pablo G.

2012-02-01

Drying of hydrophobic cavities is of interest in understanding biological self assembly, protein stability and opening and closing of ion channels. Liquid-to-vapor transition of water in confinement is associated with large kinetic barriers which preclude its study using conventional simulation techniques. Using forward flux sampling to study the kinetics of the transition between two hydrophobic surfaces, we show that a) the free energy barriers to evaporation scale linearly with the distance between the two surfaces, d; b) the evaporation rates increase as the lateral size of the surfaces, L increases, and c) the transition state to evaporation for sufficiently large L is a cylindrical vapor cavity connecting the two hydrophobic surfaces. Finally, we decouple the effects of confinement geometry and surface chemistry on the evaporation rates.

Comparison of Cf-252 thin-film sources prepared by evaporation or self-transfer

DOE PAGES

Algutifan, Noor J.; Sherman, Steven R.; Alexander, Charles W.

2014-11-29

Californium-252 (Z = 98) is valued as a potent neutron source due to its spontaneous fission decay path. Thin film sources containing Cf-252 were prepared by two techniques: evaporation and self-transfer. The sources were analyzed by alpha and gamma spectroscopy. Results indicate that self-transfer sources exhibit less alpha energy straggling and energy loss than evaporative sources. Fission fragments may also self-transfer, and sources made by self-transfer may need some decay time to reach radioactive equilibrium.

Boussinesq approximation of the Cahn-Hilliard-Navier-Stokes equations.

PubMed

Vorobev, Anatoliy

2010-11-01

We use the Cahn-Hilliard approach to model the slow dissolution dynamics of binary mixtures. An important peculiarity of the Cahn-Hilliard-Navier-Stokes equations is the necessity to use the full continuity equation even for a binary mixture of two incompressible liquids due to dependence of mixture density on concentration. The quasicompressibility of the governing equations brings a short time-scale (quasiacoustic) process that may not affect the slow dynamics but may significantly complicate the numerical treatment. Using the multiple-scale method we separate the physical processes occurring on different time scales and, ultimately, derive the equations with the filtered-out quasiacoustics. The derived equations represent the Boussinesq approximation of the Cahn-Hilliard-Navier-Stokes equations. This approximation can be further employed as a universal theoretical model for an analysis of slow thermodynamic and hydrodynamic evolution of the multiphase systems with strongly evolving and diffusing interfacial boundaries, i.e., for the processes involving dissolution/nucleation, evaporation/condensation, solidification/melting, polymerization, etc.

Growth, crystalline perfection, spectral, thermal and theoretical studies on imidazolium L-tartrate crystals.

PubMed

Meena, K; Muthu, K; Meenatchi, V; Rajasekar, M; Bhagavannarayana, G; Meenakshisundaram, S P

2014-04-24

Transparent optical quality single crystals of imidazolium L-tartrate (IMLT) were grown by conventional slow evaporation solution growth technique. Crystal structure of the as-grown IMLT was determined by single crystal X-ray diffraction analysis. Thermal analysis reveals the purity of the crystal and the sample is stable up to the melting point. Good transmittance in the visible region is observed and the band gap energy is estimated using diffuse reflectance data by the application of Kubelka-Munk algorithm. The powder X-ray diffraction study reveals the crystallinity of the as-grown crystal and it is compared with that of the experimental one. An additional peak in high resolution X-ray diffraction (HRXRD) indicates the presence of an internal structural low angle boundary. Second harmonic generation (SHG) activity of IMLT is significant as estimated by Kurtz and Perry powder technique. HOMO-LUMO energies and first-order molecular hyperpolarizability of IMLT have been evaluated using density functional theory (DFT) employing B3LYP functional and 6-31G(d,p) basis set. The optimized geometry closely resembles the ORTEP. The vibrational patterns present in the molecule are confirmed by FT-IR coinciding with theoretical patterns. Copyright © 2014 Elsevier B.V. All rights reserved.

Establishment of the structural and enhanced physicochemical properties of the cocrystal-2-benzyl amino pyridine with oxalic acid

NASA Astrophysics Data System (ADS)

Sangeetha, M.; Mathammal, R.

2017-09-01

We report on a cocrystal of 2-(benzyl amino) pyridine (BAP) with oxalic acid (OA) in the ratio 1:1. The cocrystal was synthesised and single crystals were grown under slow evaporation technique at room temperature. Single crystal X-ray diffraction (SCXRD) analysis determined the structure of the cocrystal formed and it belongs to orthorhombic system with Cc space group. It was also subjected to X-ray Powder diffraction (XRPD) to confirm the cocrystal structure. Hirshfeld surfaces and fingerprints were plotted to analyze the intermolecular interactions. Spectroscopic techniques such as FTIR, FT-Raman and NMR were carried out to identify the functional groups present in the cocrystal. The bioactivity of the cocrystal was revealed from the UV-Vis analysis. Computational Density Functional Theory (DFT) was adopted at the B3LYP/6-31+G** level to calculate the optimized geometrical parameters and the vibrational frequencies of the cocrystal. The non-linear optical property of the cocrystal was revealed from the SHG test. The different types of interactions and delocalization of charge were analysed from Natural Bond Orbital (NBO) calculations. The HOMO-LUMO energies and MEP surface maps confirmed the pharmaceutical importance of the (1:1) BAPOA cocrystal. The cocrystal has been explored for the invitro antioxidant activity and insilico molecular docking studies.

Growth, optical, thermal, mechanical and dielectric studies of sodium succinate hexahydrate (β phase) single crystal: A promising third order NLO material

NASA Astrophysics Data System (ADS)

Mageshwari, P. S. Latha; Priya, R.; Krishnan, S.; Joseph, V.; Das, S. Jerome

2016-11-01

A third order nonlinear optical (NLO)single crystals of sodium succinate hexahydrate (SSH) (β phase) has been grown by a slow evaporation growth technique using aqueous solution at ambient temperature. The lattice parameters and morphology of SSH were determined by single crystal X-ray diffraction analysis. SSH crystallizes in centrosymmetric monoclinic system with space group P 21 / c and the crystalline purity was analyzed by powder X-ray diffraction analysis. The UV-vis-NIR spectrum reveals that the crystal is transparent in the entire visible region. The recorded FT-IR spectrum verified the presence of various functional groups in the material. NMR analysis of the grown crystal confirms the structural elucidation and detects the major and minor functional groups present in the title compound. ICP-OES analysis proved the presence of sodium in SSH. TG-DTA/DSCanalysis was used to investigate the thermal stability of the material. The dielectric permittivity and dielectric loss of SSH were carried out as a function of frequency for different temperatures and the results were discussed. The mechanical stability was evaluated from Vicker's microhardness test. The third order nonlinear optical properties of SSH has been investigated employing Z-scan technique with He-Ne laser operating at 632.8 nm wavelength.

Simultaneous formation and micronization of pharmaceutical cocrystals by rapid expansion of supercritical solutions (RESS).

PubMed

Müllers, Katrin C; Paisana, Maria; Wahl, Martin A

2015-02-01

We investigated the RESS process as a means of simultaneous micronization and cocrystallization of a model drug with poor aqueous solubility. 1:1 cocrystals of ibuprofen (IBU) and nicotinamide (NA) were produced with a pilot scale unit for RESS processing.IBU and NA were dissolved in scCO2 at 30 MPa and 50°C. After 24 h, the supercritical solution was expanded at a medium CO2 flow rate of 3.8 kg/h during 60 min into an expansion vessel kept at ambient conditions. Cocrystals were identified with DSC, XRD and confocal Raman microscopy (CRM) and further characterized by SEM, specific surface area, wetting ability, solubility and dissolution testing. Judging by DSC, XRD and CRM, cocrystals with high purity could be produced with the RESS technique. Micronization via RESS was successful, since the specific surface area of RESS cocrystals was increased almost tenfold in comparison to cocrystals produced by slow solvent evaporation. Due to the additional micronization, the mean dissolution time of IBU from RESS cocrystals was decreased. RESS cocrystallization offers the advantage of combining micronization and cocrystallization in a single production step. For drugs with dissolution-limited bioavailability, RESS cocrystallization may therefore be a superior approach in comparison to established cocrystallization techniques.

Synthesis, growth and characterization of L-Phenylalaninium methanesulfonate nonlinear optical single crystal

NASA Astrophysics Data System (ADS)

Mangaiyarkarasi, K.; Ravichandran, A. T.; Anitha, K.; Manivel, A.

2018-03-01

The titled compound, L-Phenylalaninium methanesulfonate (LPA-MS) was synthesized and grown into single crystals by slow solvent evaporation solution growth technique in aqueous solution containing equimolar concentrations of L-phenylalanine and methanesulfonic acid at room temperature. The grown crystals were subjected to single crystal X-ray diffraction studies. It crystallizes in the monoclinic crystal structure with P21 space group and the unit cell parameters are a = 5.312 (10) Å, b = 8.883 (2) Å and c = 25.830 (7) Å. The functional groups of the LPA-MS crystal were confirmed with FT-IR and FT-Raman analysis. The carbon-hydrogen skeleton was confirmed with 1H NMR and 13C NMR analysis. TG-DTG and DSC studies were carried out to determine the thermal stability of the crystals. The optical transparency ranges were studied through UV-vis-spectroscopy and the crystal was found to be transparent in the visible region. The second Harmonic generation (SHG) efficiency of the grown LPA-MS crystal was measured by the Kurtz-Perry powder technique. The dipolar nature of the L-phenylalaninium methanesulfonate and the presence of the intermolecular hydrogen bonding between the molecules are the vital factors responsible for the existence of SHG activity in the crystal.

A technique based on droplet evaporation to recognize alcoholic drinks

NASA Astrophysics Data System (ADS)

González-Gutiérrez, Jorge; Pérez-Isidoro, Rosendo; Ruiz-Suárez, J. C.

2017-07-01

Chromatography is, at present, the most used technique to determine the purity of alcoholic drinks. This involves a careful separation of the components of the liquid elements. However, since this technique requires sophisticated instrumentation, there are alternative techniques such as conductivity measurements and UV-Vis and infrared spectrometries. We report here a method based on salt-induced crystallization patterns formed during the evaporation of alcoholic drops. We found that droplets of different samples form different structures upon drying, which we characterize by their radial density profiles. We prove that using the dried deposit of a spirit as a control sample, our method allows us to differentiate between pure and adulterated drinks. As a proof of concept, we study tequila.

In situ diagnosis of pulsed UV laser surface ablation of tungsten carbide hardmetal by using laser-induced optical emission spectroscopy

NASA Astrophysics Data System (ADS)

Li, Tiejun; Lou, Qihong; Wei, Yunrong; Huang, Feng; Dong, Jingxing; Liu, Jingru

2001-12-01

Surface ablation of cobalt cemented tungsten carbide hardmetal with pulsed UV laser has been in situ diagnosed by using the technique of laser-induced optical emission spectroscopy. The dependence of emission intensity of cobalt lines on number of laser shots was investigated at laser fluence of 2.5 J/cm 2. As a comparison, the reliance of emission intensity of cobalt lines as a function of laser pulse number by using pure cobalt as ablation sample was also studied at the same laser condition. It was found that for surface ablation of tungsten carbide hardmetal at laser fluence of 2.5 J/cm 2, the intensities of cobalt lines fell off dramatically in the first 300 consecutive laser shots and then slowed down to a low stable level with even more shots. For surface ablation of pure cobalt at the same laser condition, the intensities of cobalt lines remained constant more or less even after 500 laser shots and then reduced very slowly with even more shots. It was concluded that selective evaporation of cobalt at this laser fluence should be responsible for the dramatic fall-off of cobalt lines with laser shots accumulation for surface ablation of tungsten carbide hardmetal. In contrast, for surface ablation of pure cobalt, the slow reduction of cobalt lines with pulse number accumulation should be due to the formation of laser-induced crater effect.

Crystallization tendency of active pharmaceutical ingredients following rapid solvent evaporation--classification and comparison with crystallization tendency from undercooled melts.

PubMed

Van Eerdenbrugh, Bernard; Baird, Jared A; Taylor, Lynne S

2010-09-01

In this study, the crystallization behavior of a variety of compounds was studied following rapid solvent evaporation using spin coating. Initial screening to determine model compound suitability was performed using a structurally diverse set of 51 compounds in three different solvent systems [dichloromethane (DCM), a 1:1 (w/w) dichloromethane/ethanol mixture (MIX), and ethanol (EtOH)]. Of this starting set of 153 drug-solvent combinations, 93 (40 compounds) were selected for further evaluation based on solubility, chemical solution stability, and processability criteria. These systems were spin coated and their crystallization was monitored using polarized light microscopy (7 days, dry conditions). The crystallization behavior of the samples could be classified as rapid (Class I: 39 cases), intermediate (Class II: 23 cases), or slow (Class III: 31 cases). The solvent system employed influenced the classification outcome for only four of the compounds. The various compounds showed very diverse crystallization behavior. Upon comparison of classification results with those of a previous study, where cooling from the melt was used as a preparation technique, a good similarity was found whereby 68% of the cases were identically classified. Multivariate analysis was performed using a set of relevant physicochemical compound characteristics. It was found that a number of these parameters tended to differ between the different classes. These could be further interpreted in terms of the nature of the crystallization process. Additional multivariate analysis on the separate classes of compounds indicated some potential in predicting the crystallization tendency of a given compound.

Evaporation from weighing precipitation gauges: impacts on automated gauge measurements and quality assurance methods

NASA Astrophysics Data System (ADS)

Leeper, R. D.; Kochendorfer, J.

2015-06-01

Evaporation from a precipitation gauge can cause errors in the amount of measured precipitation. For automated weighing-bucket gauges, the World Meteorological Organization (WMO) suggests the use of evaporative suppressants and frequent observations to limit these biases. However, the use of evaporation suppressants is not always feasible due to environmental hazards and the added cost of maintenance, transport, and disposal of the gauge additive. In addition, research has suggested that evaporation prior to precipitation may affect precipitation measurements from auto-recording gauges operating at sub-hourly frequencies. For further evaluation, a field campaign was conducted to monitor evaporation and its impacts on the quality of precipitation measurements from gauges used at U.S. Climate Reference Network (USCRN) stations. Two Geonor gauges were collocated, with one gauge using an evaporative suppressant (referred to as Geonor-NonEvap) and the other with no suppressant (referred to as Geonor-Evap) to evaluate evaporative losses and evaporation biases on precipitation measurements. From June to August, evaporative losses from the Geonor-Evap gauge exceeded accumulated precipitation, with an average loss of 0.12 mm h-1. The impact of evaporation on precipitation measurements was sensitive to the choice of calculation method. In general, the pairwise method that utilized a longer time series to smooth out sensor noise was more sensitive to gauge evaporation (-4.6% bias with respect to control) than the weighted-average method that calculated depth change over a smaller window (<+1% bias). These results indicate that while climate and gauge design affect gauge evaporation rates, computational methods also influence the magnitude of evaporation biases on precipitation measurements. This study can be used to advance quality insurance (QA) techniques used in other automated networks to mitigate the impact of evaporation biases on precipitation measurements.

Air Conditioner Ready to Change Industry - Continuum Magazine | NREL

Science.gov Websites

create very dry air, ideal for cooling with evaporative techniques. Desiccants, which can be liquids or into an innovative "cooling core." This would marry the desiccants' capacity to create dry air using heat and evaporative coolers' capability to turn dry air into cold air. If it worked, it

Attempt to form hydride and amorphous particles, and introduction of a new evaporation method

NASA Astrophysics Data System (ADS)

Yatsuya, S.; Yamauchi, K.; Kamakura, T.; Yanagida, A.; Wakayama, H.; Mihama, K.

1985-06-01

Al and TiH 2 particles of fcc structure can be produced in an atmosphere of gaseous H 2 at reduced pressure. Al particles with definite habit are obtained, which has been never observed in the ordinary gas evaporation technique using a HV system. The habit of TiH 2 particles grown in the intermediate zone of the smoke is determined to be a dodecahedron. The growth is considered as the result of the martensite transformation from the bcc structure initially formed to the fcc structure accompanying a slight modification of the characteristic habit as observed for Ti particles. For the preparation of amorphous particles, first, the quenching rate of a particle, {dT}/{dt} was estimated to be more than {10 4°C }/{s}. Ultrafine particles of Pd 80Si 20 chosen as a test sample did not show the amorphous structure, but the crystalline. Application of the sputtering method as a new evaporation source in the gas evaporation technique is attempted. With the sputtering method, W particles with definite habits are produced.

Estimation of Regional Evapotranspiration Using Remotely Sensed Land Surface Temperature. Part 2: Application of Equilibrium Evaporation Model to Estimate Evapotranspiration by Remote Sensing Technique. [Japan

NASA Technical Reports Server (NTRS)

Kotoda, K.; Nakagawa, S.; Kai, K.; Yoshino, M. M.; Takeda, K.; Seki, K.

1985-01-01

In a humid region like Japan, it seems that the radiation term in the energy balance equation plays a more important role for evapotranspiration then does the vapor pressure difference between the surface and lower atmospheric boundary layer. A Priestley-Taylor type equation (equilibrium evaporation model) is used to estimate evapotranspiration. Net radiation, soil heat flux, and surface temperature data are obtained. Only temperature data obtained by remotely sensed techniques are used.

The physiological effects of slow breathing in the healthy human

PubMed Central

Russo, Marc A.; Santarelli, Danielle M.; O’Rourke, Dean

2017-01-01

Slow breathing practices have been adopted in the modern world across the globe due to their claimed health benefits. This has piqued the interest of researchers and clinicians who have initiated investigations into the physiological (and psychological) effects of slow breathing techniques and attempted to uncover the underlying mechanisms. The aim of this article is to provide a comprehensive overview of normal respiratory physiology and the documented physiological effects of slow breathing techniques according to research in healthy humans. The review focuses on the physiological implications to the respiratory, cardiovascular, cardiorespiratory and autonomic nervous systems, with particular focus on diaphragm activity, ventilation efficiency, haemodynamics, heart rate variability, cardiorespiratory coupling, respiratory sinus arrhythmia and sympathovagal balance. The review ends with a brief discussion of the potential clinical implications of slow breathing techniques. This is a topic that warrants further research, understanding and discussion. Key points Slow breathing practices have gained popularity in the western world due to their claimed health benefits, yet remain relatively untouched by the medical community. Investigations into the physiological effects of slow breathing have uncovered significant effects on the respiratory, cardiovascular, cardiorespiratory and autonomic nervous systems. Key findings include effects on respiratory muscle activity, ventilation efficiency, chemoreflex and baroreflex sensitivity, heart rate variability, blood flow dynamics, respiratory sinus arrhythmia, cardiorespiratory coupling, and sympathovagal balance. There appears to be potential for use of controlled slow breathing techniques as a means of optimising physiological parameters that appear to be associated with health and longevity, and that may extend to disease states; however, there is a dire need for further research into the area. Educational aims To provide a comprehensive overview of normal human respiratory physiology and the documented effects of slow breathing in healthy humans. To review and discuss the evidence and hypotheses regarding the mechanisms underlying slow breathing physiological effects in humans. To provide a definition of slow breathing and what may constitute “autonomically optimised respiration”. To open discussion on the potential clinical implications of slow breathing techniques and the need for further research. PMID:29209423

Black hole genesis of dark matter

NASA Astrophysics Data System (ADS)

Lennon, Olivier; March-Russell, John; Petrossian-Byrne, Rudin; Tillim, Hannah

2018-04-01

We present a purely gravitational infra-red-calculable production mechanism for dark matter (DM) . The source of both the DM relic abundance and the hot Standard Model (SM) plasma is a primordial density of micro black holes (BHs), which evaporate via Hawking emission into both the dark and SM sectors. The mechanism has four qualitatively different regimes depending upon whether the BH evaporation is 'fast' or 'slow' relative to the initial Hubble rate, and whether the mass of the DM particle is 'light' or 'heavy' compared to the initial BH temperature. For each of these regimes we calculate the DM yield, Y, as a function of the initial state and DM mass and spin. In the 'slow' regime Y depends on only the initial BH mass over a wide range of initial conditions, including scenarios where the BHs are a small fraction of the initial energy density. The DM is produced with a highly non-thermal energy spectrum, leading in the 'light' DM mass regime (~260 eV and above depending on DM spin) to a strong constraint from free-streaming, but also possible observational signatures in structure formation in the spin 3/2 and 2 cases. The 'heavy' regime (~1.2 × 108 GeV to MPl depending on spin) is free of these constraints and provides new possibilities for DM detection. In all cases there is a dark radiation component predicted.

Evaporation mitigation by floating modular devices

NASA Astrophysics Data System (ADS)

Hassan, M. M.; Peirson, W. L.

2016-05-01

Prolonged periods of drought and consequent evaporation from open water bodies in arid parts of Australia continue to be a threat to water availability for agricultural production. Over many parts of Australia, the annual average evaporation exceeds the annual precipitation by more than 5 times. Given its significance, it is surprising that no evaporation mitigation technique has gained widespread adoption to date. High capital and maintenance costs of manufactured products are a significant barrier to implementation. The use of directly recycled clean plastic containers as floating modular devices to mitigate evaporation has been investigated for the first time. A six-month trial at an arid zone site in Australia of this potential cost effective solution has been undertaken. The experiment was performed using clean conventional drinking water bottles as floating modules on the open water surface of 240-L tanks with three varying degrees of covering (nil, 34% and 68%). A systematic reduction in evaporation is demonstrated during the whole study period that is approximately linearly proportional to the covered surface. These results provide a potential foundation for robust evaporation mitigation with the prospect of implementing a cost-optimal design.

Sequential evaporation of water molecules from protonated water clusters: measurement of the velocity distributions of the evaporated molecules and statistical analysis.

PubMed

Berthias, F; Feketeová, L; Abdoul-Carime, H; Calvo, F; Farizon, B; Farizon, M; Märk, T D

2018-06-22

Velocity distributions of neutral water molecules evaporated after collision induced dissociation of protonated water clusters H+(H2O)n≤10 were measured using the combined correlated ion and neutral fragment time-of-flight (COINTOF) and velocity map imaging (VMI) techniques. As observed previously, all measured velocity distributions exhibit two contributions, with a low velocity part identified by statistical molecular dynamics (SMD) simulations as events obeying the Maxwell-Boltzmann statistics and a high velocity contribution corresponding to non-ergodic events in which energy redistribution is incomplete. In contrast to earlier studies, where the evaporation of a single molecule was probed, the present study is concerned with events involving the evaporation of up to five water molecules. In particular, we discuss here in detail the cases of two and three evaporated molecules. Evaporation of several water molecules after CID can be interpreted in general as a sequential evaporation process. In addition to the SMD calculations, a Monte Carlo (MC) based simulation was developed allowing the reconstruction of the velocity distribution produced by the evaporation of m molecules from H+(H2O)n≤10 cluster ions using the measured velocity distributions for singly evaporated molecules as the input. The observed broadening of the low-velocity part of the distributions for the evaporation of two and three molecules as compared to the width for the evaporation of a single molecule results from the cumulative recoil velocity of the successive ion residues as well as the intrinsically broader distributions for decreasingly smaller parent clusters. Further MC simulations were carried out assuming that a certain proportion of non-ergodic events is responsible for the first evaporation in such a sequential evaporation series, thereby allowing to model the entire velocity distribution.

Thermally evaporated conformal thin films on non-traditional/non-planar substrates

NASA Astrophysics Data System (ADS)

Pulsifer, Drew Patrick

Conformal thin films have a wide variety of uses in the microelectronics, optics, and coatings industries. The ever-increasing capabilities of these conformal thin films have enabled tremendous technological advancement in the last half century. During this period, new thin-film deposition techniques have been developed and refined. While these techniques have remarkable performance for traditional applications which utilize planar substrates such as silicon wafers, they are not suitable for the conformal coating of non-traditional substrates such as biological material. The process of thermally evaporating a material under vacuum conditions is one of the oldest thin-film deposition techniques which is able to produce functional film morphologies. A drawback of thermally evaporated thin films is that they are not intrinsically conformal. To overcome this, while maintaining the advantages of thermal evaporation, a procedure for varying the substrates orientation with respect to the incident vapor flux during deposition was developed immediately prior to the research undertaken for this doctoral dissertation. This process was shown to greatly improve the conformality of thermally evaporated thin films. This development allows for several applications of thermally evaporated conformal thin films on non-planar/non-traditional substrates. Three settings in which to evaluate the improved conformal deposition of thermally evaporated thin films were investigated for this dissertation. In these settings the thin-film morphologies are of different types. In the first setting, a bioreplication approach was used to fabricate artificial visual decoys for the invasive species Agrilus planipennis, commonly known as the emerald ash borer (EAB). The mating behavior of this species involves an overflying EAB male pouncing on an EAB female at rest on an ash leaflet before copulation. The male spots the female on the leaflet by visually detecting the iridescent green color of the female's elytra. As rearing EAB and then deploying dead females as decoys is both arduous and inconvenient, the development of an artificial decoy would be of great interest to entomologists and foresters. A dead female EAB was used to make a negative die of nickel and a positive die of epoxy. The process of fabricating the paired dies utilized thermally evaporated conformal thin films in several critical steps. In order to conformally coat the EAB with nickel, the substrate stage holding the female EAB was periodically rocked and rotated during the deposition. This process was designed to result in a uniform thin film of ˜ 500-nm thickness with dense morphology. The nickel film was then reinforced through an electroforming process and mounted in a fixture which allowed it to be heated electrically. The corresponding positive die was replicated from the negative die through a series of successive castings. The final EAB positive die was fabricated from a hard epoxy material and attached to a fixture which allowed it to be heated while being pressed into the negative die. Decoys were then made by first depositing a quarter-wave-stack Bragg reflector on a polymer sheet and then stamping it with the pair of matched negative and positive dies to take the shape of the upper surface of an EAB female. As nearly 100 decoys were fabricated from just one EAB female, this bioreplication process is industrially scalable. Preliminary results from field trapping tests are indicative of success. For the second setting, a method of developing latent fingermarks with thermally evaporated conformal thin films was developed. Fingermarks have long been used to identify the individual who left them behind when he/she touched an object with the friction ridges of his/her hands. In many cases the fingermark which is left behind consists of sebaceous secretions which are not clearly visible under normal conditions. In order to make the fingermarks visible and identifiable, they are traditionally developed by either a physical technique which relies on a material preferentially sticking to sebaceous materials or a chemical technique which relies on a reaction with material within the fingermark. In this application, a columnar thin film (CTF) is deposited conformally over both the fingermark and the underlying substrate. The CTF is produced by the conformal-evaporated-film-by-rotation method, wherein the substrate with the fingermark upon it is held obliquely with respect to a vapor flux in a vacuum chamber. The substrate is then rapidly rotated about its surface normal resulting in a conformal film with columnar morphology. This technique was optimized for several substrates and compared with traditional development techniques. CTF development was found to be superior to traditional techniques in several cases. Use of the CTF was investigated for several types of particularly difficult to develop fingermarks such as those which consist of both bloody and nonbloody areas, and fingermarks on fired cartridge casings. The CTF technique's sensitivity was also compared to that of traditional development techniques. Finally, the CTF technique was compared with another thin film deposition technique called vacuum-metal deposition. (Abstract shortened by UMI.).

Specificity Switching Pathways in Thermal and Mass Evaporation of Multicomponent Hydrocarbon Droplets: A Mesoscopic Observation.

PubMed

Nasiri, Rasoul; Luo, Kai H

2017-07-10

For well over one century, the Hertz-Knudsen equation has established the relationship between thermal - mass transfer coefficients through a liquid - vapour interface and evaporation rate. These coefficients, however, have been often separately estimated for one-component equilibrium systems and their simultaneous influences on evaporation rate of fuel droplets in multicomponent systems have yet to be investigated at the atomic level. Here we first apply atomistic simulation techniques and quantum/statistical mechanics methods to understand how thermal and mass evaporation effects are controlled kinetically/thermodynamically. We then present a new development of a hybrid method of quantum transition state theory/improved kinetic gas theory, for multicomponent hydrocarbon systems to investigate how concerted-distinct conformational changes of hydrocarbons at the interface affect the evaporation rate. The results of this work provide an important physical concept in fundamental understanding of atomistic pathways in topological interface transitions of chain molecules, resolving an open problem in kinetics of fuel droplets evaporation.

Fast Evaporation of Spreading Droplets of Colloidal Suspensions

NASA Astrophysics Data System (ADS)

Maki, Kara; Kumar, Satish

2011-11-01

When a coffee droplet dries on a countertop, a dark ring of coffee solute is left behind, a phenomenon often referred to as ``the coffee-ring effect.'' A closely related yet less-well-explored phenomenon is the formation of a layer of particles, or skin, at the surface of the droplet. In this work, we explore the behavior of a mathematical model that can qualitatively describe both phenomena. We consider a thin axisymmetric droplet of a colloidal suspension on a horizontal substrate undergoing spreading and rapid evaporation. The lubrication approximation is applied to simplify the mass and momentum conservation equations, and the colloidal particles are allowed to influence droplet rheology through their effect on the viscosity. By describing the transport of the colloidal particles with the full convection-diffusion equation, we are able to capture depthwise gradients in particle concentration and thus describe skin formation, a feature neglected in prior models of droplet evaporation. Whereas capillarity creates a flow that drives particles to the contact line to produce a coffee-ring, Marangoni flows can compete with this and promote skin formation. Increases in viscosity due to particle concentration slow down droplet dynamics, and can lead to a significant reduction in the spreading rate.

Clogging of Manifolds with Evaporatively Frozen Propellants. Part 2; Analysis

NASA Technical Reports Server (NTRS)

Simmon, J. A.; Gift, R. D.; Spurlock, J. M.

1966-01-01

The mechanisms of evaporative freezing of leaking propellant and the creation of flow stoppages within injector manifolds is discussed. A quantitative analysis of the conditions, including the existence of minimum and maximum leak rates, for the accumulation of evaporatively frozen propellant is presented. Clogging of the injector manifolds of the Apollo SPS and the Gemini OAMS engines by the freezing of leaking propellant is predicted and the seriousness of the consequences are discussed. Based on the analysis a realistic evaluation of selected techniques to eliminate flow stoppages by frozen propellant is made.

Producing carbon stripper foils containing boron

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

Stoner, J. O. Jr.

2012-12-19

Parameters being actively tested by the accelerator community for the purpose of extending carbon stripper foil lifetimes in fast ion beams include methods of deposition, parting agents, mounting techniques, support (fork) materials, and inclusion of alloying elements, particularly boron. Specialized production apparatus is required for either sequential deposition or co-deposition of boron in carbon foils. A dual-use vacuum evaporator for arc evaporation of carbon and electron-beam evaporation of boron and other materials has been built for such development. Production of both carbon and boron foils has begun and improvements are in progress.

Evaporation dynamics of a sessile droplet on glass surfaces with fluoropolymer coatings: focusing on the final stage of thin droplet evaporation.

PubMed

Gatapova, Elizaveta Ya; Shonina, Anna M; Safonov, Alexey I; Sulyaeva, Veronica S; Kabov, Oleg A

2018-03-07

The evaporation dynamics of a water droplet with an initial volume of 2 μl from glass surfaces with fluoropolymer coatings are investigated using the shadow technique and an optical microscope. The droplet profile for a contact angle of less than 5° is constructed using an image-analyzing interference technique, and evaporation dynamics are investigated at the final stage. We coated the glass slides with a thin film of a fluoropolymer by the hot-wire chemical vapor deposition method at different deposition modes depending on the deposition pressure and the temperature of the activating wire. The resulting surfaces have different structures affecting the wetting properties. Droplet evaporation from a constant contact radius mode in the early stage of evaporation was found followed by the mode where both contact angle and contact radius simultaneously vary in time (final stage) regardless of wettability of the coated surfaces. We found that depinning occurs at small contact angles of 2.2-4.7° for all samples, which are smaller than the measured receding contact angles. This is explained by imbibition of the liquid into the developed surface of the "soft" coating that leads to formation of thin droplets completely wetting the surface. The final stage, which is little discussed in the literature, is also recorded. We have singled out a substage where the contact line velocity is abruptly increasing for all coated and uncoated surfaces. The critical droplet height corresponding to the transition to this substage is about 2 μm with R/h = 107. The duration of this substage is the same for all coated and uncoated surfaces. Droplets observed at this substage for all the tested surfaces are axisymmetric. The specific evaporation rate clearly demonstrates an abrupt increase at the final substage of the droplet evaporation. The classical R 2 law is justified for the complete wetting situation where the droplet is disappearing in an axisymmetric manner.

Investigations on structural, optical, electrical, mechanical and third-order nonlinear behaviour of 3-aminopyridinium 2,4-dinitrophenolate single crystal

NASA Astrophysics Data System (ADS)

Mohanbabu, B.; Bharathikannan, R.; Siva, G.

2017-10-01

The single crystals of 3-aminopyridinium 2,4-dinitrophenolate (APDP) have been synthesized and grown by slow evaporation technique at room temperature. The crystal system was identified and lattice dimensions were measured from the single-crystal X-ray diffraction (SXRD) analysis. UV-visible absorption and transmittance spectra have been recorded in the region between 250 and 1100 nm. The different vibrational modes of the molecule were studied by Fourier transform infrared (FTIR) spectroscopic analysis. The decreasing tendency of dielectric constant with increasing frequency was analysed in dielectric study. The polarizability value calculated using Penn analysis well agrees with the value calculated using Clausius-Mossotti equation. The photoconductivity and photoluminescence behaviour were also studied on grown APDP crystal. The mechanical strength of the crystal has been studied using a Vickers' microhardness test. The stiffness constant and yield strength of the crystal were also calculated from the microhardness test. The third-order nonlinear optical parameters such as refractive index, absorption coefficient and third-order susceptibility were estimated by Z-scan studies.

Syntheses, structural characterization, and DPPH radical scavenging activity of cocrystals of caffeine with 1- and 2-naphthoxyacetic acids

NASA Astrophysics Data System (ADS)

Suresh Kumar, G. S.; Seethalakshmi, P. G.; Sumathi, D.; Bhuvanesh, N.; Kumaresan, S.

2013-03-01

Caffeine:1-naphthoxyacetic acid [(caf)(1-naa)] and caffeine:2-naphthoxyacetic acid [(caf)(2-naa)] cocrystals have been synthesized and single crystals were grown by slow evaporation technique. The structures of the grown crystals were elucidated using single crystal X-ray diffraction analysis. Both the cocrystals belong to the monoclinic crystallographic system with space group P21/c, Z = 4, and α = γ = 90°, whereas β = 111.4244(18)° for [(caf)(1-naa)] and β = 109.281(6)° for [(caf)(2-naa)]. The crystal packing is predominantly stabilized by hydrogen bonding and π-π stacking interactions. The presence of unionized -COOH functional group in both the cocrystals was identified by FTIR spectral analysis. Thermal behavior and stability of both the cocrystals were studied by TGA/DTA analyses. Solvent-free formation of these cocrystals was confirmed by powder X-ray diffraction analyses. The theoretical energy of cocrystals showed that the formers have higher energy than cocrystals 1 and 2. DPPH radical scavenging activity of cocrystals 1 and 2 is slightly greater than the formers.

Investigations on synthesis, growth and physicochemical properties of semi-organic NLO crystal bis(thiourea) ammonium nitrate for nonlinear frequency conversion

NASA Astrophysics Data System (ADS)

Anbarasi, A.; Ravi Kumar, S. M.; Sundar, G. J. Shanmuga; Mosses, M. Allen; Raj, M. Packiya; Prabhakaran, M.; Ravisankar, R.; Gunaseelan, R.

2017-10-01

Bis(thiourea) ammonium nitrate (BTAN), a new nonlinear optical crystal was grown successfully by slow evaporation technique using water as solvent at room temperature. The grown crystals were optically good quality with dimensions upto 10 × 6 × 3 mm3. Single crystal X-Ray diffraction analysis reveals that the crystal lattice is orthorhombic. From Powder X-ray diffraction analysis the diffraction planes have been indexed. The presence of the various functional groups of BTAN was identified through FTIR spectroscopic analysis. UV cut-off wavelength was observed from optical absorbance spectrum and it was found to be 240 nm. Second harmonic efficiency was determined using Kurtz powder method in comparison with KDP to confirm the nonlinearity of the material. Thermal analysis confirmed that grown crystal is thermally stable upto 184 °C. Microhardness studies show that hardness number (Hv) increases with load. Conductivity measurements such as dielectric, ac and photoconductivity were studied. Growth mechanism and surface features of the as grown single crystal was analysed by chemical etching analysis.

Structural versus electrical properties of an organic-inorganic hybrid material based on sulfate

NASA Astrophysics Data System (ADS)

Ben Rached, Asma; Guionneau, Philippe; Lebraud, Eric; Mhiri, Tahar; Elaoud, Zakaria

2017-01-01

A new organo-sulfate compound is obtained by slow evaporation at room temperature and is characterized by powder and single-crystal X-ray diffraction (XRD) at variable temperatures. The benzylammonium monohydrogenosulfate of formula C6H5CH2NH3+. HSO4-, denoted (BAS), crystallizes in the monoclinic system P21/c space group with the following parameters at room temperature: a=5.623(5)Å, b=20.239(5) Å, c=8.188(5)Å, β=94.104(5)°. The crystal structure consists of infinite parallel two-dimensional planes built by HSO4- anions and C6H5CH2NH3+ cations interconnected by strong O-H….. O and N-H….. O hydrogen bonds. A phase transition is detected at 350 K by differential scanning calorimetry (DSC) and confirmed by powder XRD. Conductivity measurements using the impedance spectroscopy technique allow to determine the conductivity relaxation parameters associated with the H+ conduction from an analysis of the M"/M"max spectrum measured in a wide temperature range. Transport properties of this material appear to be due to an H+ ion hopping mechanism.

Growth, structural, optical, piezoelectric and etching analysis of L-lysine p-nitrophenolate monohydrate single crystals

NASA Astrophysics Data System (ADS)

Alexandar, A.; Lakshmanan, A.; Sakthy Priya, S.; Surendran, P.; Rameshkumar, P.

2017-09-01

Nonlinear optical single crystals of L-lysine p-nitrophenolate monohydrate (LLPNP) were grown in aqueous solution by the slow evaporation solution technique (SEST). The grown crystals were subjected to powder X-ray diffraction analysis, (PXRD) and it was found that the title compound was crystallized in the orthorhombic crystal system with noncentrosymmetric space group of P212121. The vibrational frequencies of various functional groups present in the crystal were analyzed using the FTIR spectrum with a wavenumber range between 450 cm-1 and 4000 cm-1. The microhardness analysis of the sample revealed that the crystal belongs to the soft material category. Piezoelectric analysis was performed to measure the value of the piezoelectric (d33) coefficient. Blue light emission of the material was confirmed using the photoluminescence spectrum. Thermal stability of the grown crystal was analyzed using a melting point apparatus and it was found that the LLPNP is stable upto 175∘C. Etching analysis was performed at various durations, in order to identify the surface properties of the LLPNP crystal.

Theoretical and experimental evaluation of a new organic proton transfer crystal aminoguanidinium p-nitrobenzoate monohydrate for optical limiting applications

NASA Astrophysics Data System (ADS)

Shanmugavadivu, T.; Senthilkumar, K.; Dhandapani, M.; Muthuraja, P.; Balachandar, S.; Sethu Raman, M.

2017-12-01

Aminoguanidinium p-nitrobenzoate monohydrate (AGPNB), an organic third order nonlinear crystal, was successfully grown by the slow evaporation technique. Single crystal XRD analysis reveals that the grown crystal belongs to monoclinic system with P21/n space group. FT-IR, 1H and 13C NMR spectroscopic studies were carried out to confirm the proton transfer. Optical and thermal suitability were assessed by UV-NIR and TG-DTA studies. Hirshfeld surface analysis predicts that the O⋯H/H⋯O interactions dominated over the crystal structure. Third order nonlinearity was studied by Z-scan analysis and it is found that AGPNB can be used as a reverse satuarble absorption (RSA) based optical limiter at 632.8 nm. Computational studies, such as geometry optimization, Natural bond orbital (NBO) analysis, Mulliken population analysis and Molecular electrostatic potential (MEP) were performed at B3LYP/6-311G(d,p) level of theory. The calculated first order hyperpolarizability of AGPNB is found to be 35 times that of urea.

Synthesis and physicochemical properties of bis(L-asparaginato) zinc(II): A promising new semiorganic crystal with high laser damage threshold for shorter wavelength generation

NASA Astrophysics Data System (ADS)

Subhashini, R.; Arjunan, S.

2018-05-01

An exceedingly apparent nonlinear semiorganic optical crystals of bis(L-asparaginato)zinc(II) [BLAZ], was synthesized by a traditional slow evaporation solution growth technique. The cell parameters were estimated from single crystal X-ray diffraction analysis. Spectroscopic study substantiates the presence of functional groups. The UV spectrum shows the sustenance of wide transparency window and several optical constants, such as extinction coefficient (K), refractive index, optical conductivity and electric susceptibility with real and imaginary parts of dielectric constant were calculated using the transmittance data. The fluorescence emission spectrum of the crystal pronounces red emission. The laser induced surface damage threshold of the crystal was measured using Nd:YAG laser. The output intensity of second harmonic generation was estimated using the Kurtz and Perry powder method. The hardness stability was investigated by Vickers microhardness test. The decomposition and thermal stability of the compound were scrutinized by TGA-DSC studies. Dielectric studies were carried out to anatomize the electrical properties of the crystal. SEM analysis reveals the existence of minute crystallites on the growth surface.

Screening and structural elucidation of the zwitterionic cocrystal o-picolinic acid with p-nitro aniline

NASA Astrophysics Data System (ADS)

Mekala, R.; Jagdish, P.; Mathammal, R.; Sangeetha, K.

2017-04-01

The cocrystal was screened by solvent drop grinding method and the crystals were grown by slow evaporation method at ambient conditions. The cocrystal formation of o-picolinic acid with p-nitro aniline was initially analysed by powder X-ray diffraction. Further the structural properties of the grown crystal were confirmed by the single X-ray diffraction which indicates that the cocrystal were connected by the strong N+sbnd H-⋯O hydrogen bond interaction. The cell parameters of the grown crystal were a = 14.2144(5) Å, b = 5.7558(2) Å, c = 16.0539(6) Å. The functional groups were identified using Fourier transform infrared and Raman spectral analysis. The excitation and emission state of the sample was analysed by the UV-Visible and Fluorescence studies. The red emission was observed from the Fluorescence studies. NMR studies revealed the chemical shift of the cocrystal. Thermal stability and its melting behaviour were studied by TGA and DSC analytical techniques. Electrical behaviour was studied using the dielectric studies. The intermolecular charge transfer within the molecule were analysed using HOMO- LUMO plots.

Growth of propyl-p-hydroxybenzoate single crystals and its characterizations

NASA Astrophysics Data System (ADS)

Karunagaran, N.; Ramasamy, P.

2012-06-01

Single crystals of Propyl-p-hydroxybenzoate (PHB) crystals have been grown by slow evaporation solution technique (SEST) using methanol as a solvent. The PHB single crystal of dimension up to 27×16×8 mm3 has been grown in a period of 18 days at room temperature. The optical transparency of the grown PHB crystal has been measured on (212) plane by UV-Vis-NIR spectrophotometer. The crystal has 60% of transparency in the entire visible region. The thermo gravimetric analysis (TG) and differential thermal analysis (DTA) studies reveal that the crystal is thermally stable up to 99°C. The mechanical strength of the grown PHB crystal is measured using Vickers microhardness tester. The chemical etching studies were carried out on (212) plane using methanol etchant. The laser damage threshold of PHB crystal is 1.3 GW/cm2. The dielectric properties have been investigated. The birefringence value is found to be 0.10148 at the wavelength of 504 nm. The refractive index of grown PHB single crystal is 1.6753.

Experimental and quantum chemical studies of a new organic proton transfer compound, 1H-imidazole-3-ium-3-hydroxy-2,4,6-trinitrophenolate

NASA Astrophysics Data System (ADS)

Dhamodharan, P.; Sathya, K.; Dhandapani, M.

2018-02-01

A new proton transfer compound, 1H-imidazole-3-ium-3-hydroxy-2,4,6-trinitrophenolate (IMHTP), was crystallized by slow evaporation-solution growth technique. 1H and 13C NMR spectral studies confirm the molecular structure of the grown crystal. Single crystal X-ray diffraction study confirms that IMHTP crystallizes in monoclinic system with space group P21/c. Thermal curves (TG/DTA) show that the material is thermally stable up to 198 °C. The crystal emits fluorescence at 510 nm, proving its utility in making green light emitting materials in optical applications. The stable molecular structure was optimized by Gaussian 09 program with B3LYP/6-311++G(d,p) level of basis set. The frontier molecular orbital study shows that the charge transfer interaction occurs within the complex. The calculated first-order hyperpolarizability value of IMHTP is 44 times higher than that the reference material, urea. The electrostatic potential map was used to probe into electrophilic and nucleophilic reactive sites present in the molecule.

Synthesis, self-assembly, and properties of Mn doped ZnO nanoparticles.

PubMed

Barick, K C; Bahadur, D

2007-06-01

We report here a novel process to prepare Mn doped ZnO nanoparticles by a soft chemical route at low temperature. The synthesis process is based on the hydrolysis of zinc acetate dihydrate and manganese acetate tetrahydrate heated under reflux to 160-175 degrees C using diethylene glycol as a solvent. X-ray diffraction analysis reveals that the Mn doped ZnO crystallizes in a wurtzite structure with crystal size of 15-25 nm. These nano size crystallites of Mn doped ZnO self-organize into polydisperse spheres in size ranging from 100-400 nm. Transmission Electron Microscopy image also shows that each sphere is made up of numerous nanocrystals of average diameter 15-25 nm. By means of X-ray photoelectron spectroscopy and electron spin resonance spectroscopy, we determined the valence state of Mn ions as 2+. These nanoparticles were found to be ferromagnetic at room temperature. Monodisperse porous spheres (approximately 250 nm) were obtained by size selective separation technique and then self-assembled in a closed pack periodic array through sedimentation with slow solvent evaporation, which gives strong opalescence in visible region.

Crystal growth, structural, optical, thermal and dielectric properties of lithium hydrogen oxalate monohydrate single crystal

NASA Astrophysics Data System (ADS)

Chandran, Senthilkumar; Paulraj, Rajesh; Ramasamy, P.

2017-11-01

The vibrational groups of the lithium hydrogen oxalate monohydrate have been investigated by FTIR and FT- Raman analyses. It has low absorbance in the UV-Vis-NIR region. The laser damage threshold study confirms that the material withstands upto 30 mJ with time of 7 s, after that circular dot damage is seen on the surface. The dark region of the surface damage spot occurs due to the thermal effects. The material is thermally stable upto 93 °C and there is no weight loss below this temperature. The dielectric studies were carried out at the frequency regions of 1 kHz-1 MHz and different temperatures from 40 °C to 80 °C. Semi-organic non-linear optical (NLO) single crystal lithium hydrogen oxalate monohydrate has been grown by slow evaporation solution growth technique. The Hirshfeld surface analysis was performed to understand the different intermolecular interactions in the title compound. The fingerprint plots contain the highest portion of H⋯O/O⋯H (48.3%) interactions.

Design, structural investigation and physicochemical properties of benzotriazolium m-nitrophthalate monohydrate single crystals

NASA Astrophysics Data System (ADS)

Mekala, R.; Mani, Rajaboopathi; Jagdish, P.; Mathammal, R.

2018-04-01

The single crystals of organic salt benzotriazolium m-nitrophthalate monohydrate were grown by slow evaporation technique. It crystallizes in orthorhombic system with space group Pbca. The molecular interactions of the compound have been pictured using Hirshfeld surfaces and fingerprints plots and the results were compared with BZD+·mNPA-. The functional groups were identified by FTIR and FT-Raman spectra. The proton transfer from acid to base was identified from the 1H and 13C NMR spectra. The absorption and emission spectrum of BTA+·mNPA-·H2O was recorded in aqueous solution and different solvents, respectively The HOMO and LUMO energy gap of benzotriazole and BTA+·mNPA-·H2O were calculated using density functional theory (DFT). The thermal stability and melting point of hydrated salt was analysed and compared by TG-DTG/DSC study. The anti-oxidant activity of the title compound was evaluated by DPPH and ABTS+ Radical scavenging assay. The anti-microbial and anti-cancer activity showed a potential impact in the crystal.

Dielectric, optical and mechanical studies of phenolic polyene OH1 organic electrooptic crystal

NASA Astrophysics Data System (ADS)

Bharath, D.; Kalainathan, S.

2014-11-01

2-{3-[2-(4-Hydroxyphenyl) vinyl]-5, 5-dimethylcyclo-hex-2-en-1-ylidene}malononitrile (OH1) phenolic locked polyene organic material has been synthesized by the Knoevenagel condensation method. OH1 single crystals were grown in methanol by a slow evaporation method. In order to avoid the multinucleation and reduce the metastable zone width, phosphoric acid is added in different concentrations. The linear optical property of OH1 crystal has been studied using UV-vis-NIR spectroscopy in the wavelength range 190-1100 nm and optical constants are calculated theoretically. The magnitude of nonlinear refractive index (10-12 m2/W), nonlinear absorption (10-6 m/W) and third order nonlinear susceptibility (10-6 esu) has been studied using a Z-scan technique. Dielectric property of OH1 crystal has been studied in frequency range 50 Hz-5 MHz. Photoluminescence spectrum was recorded using a xenon lamp in the range of 450-700 nm. Laser optical damage threshold of OH1 crystal was obtained (0.62 GW/cm2) using a pulsed Nd-YAG laser (1064 nm) of repetition rate 10 ns.

Influence of VO2+ ions on structural and optical properties of potassium succinate-succinic acid single crystal for non-linear optical applications

NASA Astrophysics Data System (ADS)

Juliet sheela, K.; Subramanian, P.

2018-04-01

A transparent and good optical quality semi organic single crystal of vanadium doped potassium succinate-succinic acid (KSSA) was synthesized by slow evaporation technique at room temperature. The structural perfection was supported by the powder XRD of the KSSA-VO2+ single crystal. Optical behavior of the material was discovered from the absorption and transmission spectra of UV-vis-NIR characterization. Functional group and presence of metal ion in the specimen are depicted from FTIR traces. From the photoluminescence studies, emission of wavelength in the violet region (418 nm) at the excitation of 243 nm could be ascertained. EDAX, SEM measurements identify presence of elements and pictures the step-line growth and the imperfection presents in the grown crystal. EPR analysis extracts the information about the local site symmetry around the impurity ion, molecular orbital coefficients, admixture coefficients and ground state wave function of VO2+ doped KSSA single crystal. Second harmonic generation (SHG) efficiency of the grown crystal was investigated to explore the NLO characteristic of the material.

Laser-induced fluorescence imaging of acetone inside evaporating and burning fuel droplets

NASA Astrophysics Data System (ADS)

Shringi, D. S.; Shaw, B. D.; Dwyer, H. A.

2009-01-01

Laser-induced fluorescence was used to visualize acetone fields inside individual droplets of pure acetone as well as droplets composed of methanol or 1-propanol initially mixed with acetone. Droplets were supported on a horizontal wire and two vaporization conditions were investigated: (1) slow evaporation in room air and (2) droplet combustion, which leads to substantially faster droplet surface regression rates. Acetone was preferentially gasified, causing its concentration in droplets to drop in time with resultant decreases in acetone fluorescence intensities. Slowly vaporizing droplets did not exhibit large spatial variations of fluorescence within droplets, indicating that these droplets were relatively well mixed. Ignition of droplets led to significant variations in fluorescence intensities within droplets, indicating that these droplets were not well mixed. Ignited droplets composed of mixtures of 1-propanol and acetone showed large time-varying changes in shapes for higher acetone concentrations, suggesting that bubble formation was occurring in these droplets.

Evaporative cooling of speleothem drip water

PubMed Central

Cuthbert, M. O.; Rau, G. C.; Andersen, M. S.; Roshan, H.; Rutlidge, H.; Marjo, C. E.; Markowska, M.; Jex, C. N.; Graham, P. W.; Mariethoz, G.; Acworth, R. I.; Baker, A.

2014-01-01

This study describes the first use of concurrent high-precision temperature and drip rate monitoring to explore what controls the temperature of speleothem forming drip water. Two contrasting sites, one with fast transient and one with slow constant dripping, in a temperate semi-arid location (Wellington, NSW, Australia), exhibit drip water temperatures which deviate significantly from the cave air temperature. We confirm the hypothesis that evaporative cooling is the dominant, but so far unattributed, control causing significant disequilibrium between drip water and host rock/air temperatures. The amount of cooling is dependent on the drip rate, relative humidity and ventilation. Our results have implications for the interpretation of temperature-sensitive, speleothem climate proxies such as δ18O, cave microecology and the use of heat as a tracer in karst. Understanding the processes controlling the temperature of speleothem-forming cave drip waters is vital for assessing the reliability of such deposits as archives of climate change. PMID:24895139

The Effect of Liquid Nitrogen on Bone Graft Survival.

PubMed

Sirinoglu, Hakan; Çilingir, Özlem Tuğçe; Çelebiler, Ozhan; Ercan, Feriha; Numanoglu, Ayhan

2015-08-01

Liquid nitrogen is used in medicine for cancer treatment and tissue preservation; however, bone viability after its application is controversial. This study aims to evaluate both the tissue viability and the clinical and histopathologic findings following liquid nitrogen application with different thawing techniques in rats. Mandibular bone grafts were taken from 45 Wistar rats and freezed in liquid nitrogen for 20 minutes. In the rapid-thawing technique (Rapid Thawing-1, Rapid Thawing-2), the grafts were held for 20 minutes in room temperature; in the slow-thawing technique (Slow Thawing-1, Slow Thawing-2), 20 minutes in -20°C, 20 minutes in +4°C, and 20 minutes in room temperature, respectively. In Rapid Thawing-2 and Slow Thawing-2 groups, autografts were implanted to their origin for 3 weeks and bone staining with India ink was performed and samples taken for histologic examination. The amount of cells and blood vessels and the density of bone canaliculi were significantly reduced in Rapid Thawing-1 and Slow Thawing-1 groups comparing to the Control group. However, the reduction rate was more significant in the Slow Thawing-1 group. Histomorphometric evaluation of the healing autografts after 3 weeks revealed that the decreased amounts of canaliculi were not changed in Slow Thawing-2 group. The study results demonstrated that bone tissue survives after liquid nitrogen treatment regardless of the performed thawing technique; however, slow thawing causes more tissue damage and metabolism impairment. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Comparison of evaporative fluxes from porous surfaces resolved by remotely sensed and in-situ temperature and soil moisture data

NASA Astrophysics Data System (ADS)

Wallen, B.; Trautz, A.; Smits, K. M.

2014-12-01

The estimation of evaporation has important implications in modeling climate at the regional and global scale, the hydrological cycle and estimating environmental stress on agricultural systems. In field and laboratory studies, remote sensing and in-situ techniques are used to collect thermal and soil moisture data of the soil surface and subsurface which is then used to estimate evaporative fluxes, oftentimes using the sensible heat balance method. Nonetheless, few studies exist that compare the methods due to limited data availability and the complexity of many of the techniques, making it difficult to understand flux estimates. This work compares different methods used to quantify evaporative flux based on remotely sensed and in-situ temperature and soil moisture data. A series of four laboratory experiments were performed under ambient and elevated air temperature conditions with homogeneous and heterogeneous soil configurations in a small two-dimensional soil tank interfaced with a small wind tunnel apparatus. The soil tank and wind tunnel were outfitted with a suite of sensors that measured soil temperature (surface and subsurface), air temperature, soil moisture, and tank weight. Air and soil temperature measurements were obtained using infrared thermography, heat pulse sensors and thermistors. Spatial and temporal thermal data were numerically inverted to obtain the evaporative flux. These values were then compared with rates of mass loss from direct weighing of the samples. Results demonstrate the applicability of different methods under different surface boundary conditions; no one method was deemed most applicable under every condition. Infrared thermography combined with the sensible heat balance method was best able to determine evaporative fluxes under stage 1 conditions while distributed temperature sensing combined with the sensible heat balance method best determined stage 2 evaporation. The approaches that appear most promising for determining the surface energy balance incorporates soil moisture rate of change over time and atmospheric conditions immediately above the soil surface. An understanding of the fidelity regarding predicted evaporation rates based upon stages of evaporation enables a more deliberate selection of the suite of sensors required for data collection.

Critical Evaluation of Soil Pore Water Extraction Methods on a Natural Soil

NASA Astrophysics Data System (ADS)

Orlowski, Natalie; Pratt, Dyan; Breuer, Lutz; McDonnell, Jeffrey

2017-04-01

Soil pore water extraction is an important component in ecohydrological studies for the measurement of δ2H and δ18O. The effect of pore water extraction technique on resultant isotopic signature is poorly understood. Here we present results of an intercomparison of commonly applied lab-based soil water extraction techniques on a natural soil: high pressure mechanical squeezing, centrifugation, direct vapor equilibration, microwave extraction, and two types of cryogenic extraction systems. We applied these extraction methods to a natural summer-dry (gravimetric water contents ranging from 8% to 15%) glacio-lacustrine, moderately fine textured clayey soil; excavated in 10 cm sampling increments to a depth of 1 meter. Isotope results were analyzed via OA-ICOS and compared for each extraction technique that produced liquid water. From our previous intercomparison study among the same extraction techniques but with standard soils, we discovered that extraction methods are not comparable. We therefore tested the null hypothesis that all extraction techniques would be able to replicate the natural evaporation front in a comparable manner occurring in a summer-dry soil. Our results showed that the extraction technique utilized had a significant effect on the soil water isotopic composition. High pressure mechanical squeezing and vapor equilibration techniques produced similar results with similarly sloped evaporation lines. Due to the nature of soil properties and dryness, centrifugation was unsuccessful in obtaining pore water for isotopic analysis. Cryogenic extraction on both tested techniques produced similar results to each other on a similar sloping evaporation line, but dissimilar with depth.

Water and Ethanol Droplet Wetting Transition during Evaporation on Omniphobic Surfaces

PubMed Central

Chen, Xuemei; Weibel, Justin A.; Garimella, Suresh V.

2015-01-01

Omniphobic surfaces with reentrant microstructures have been investigated for a range of applications, but the evaporation of high- and low-surface-tension liquid droplets placed on such surfaces has not been rigorously studied. In this work, we develop a technique to fabricate omniphobic surfaces on copper substrates to allow for a systematic examination of the effects of surface topography on the evaporation dynamics of water and ethanol droplets. Compared to a water droplet, the ethanol droplet not only evaporates faster, but also inhibits Cassie-to-Wenzel wetting transitions on surfaces with certain geometries. We use an interfacial energy-based description of the system, including the transition energy barrier and triple line energy, to explain the underlying transition mechanism and behaviour observed. Suppression of the wetting transition during evaporation of droplets provides an important metric for evaluating the robustness of omniphobic surfaces requiring such functionality. PMID:26603940

Application of thermal model for pan evaporation to the hydrology of a defined medium, the sponge

NASA Technical Reports Server (NTRS)

Trenchard, M. H.; Artley, J. A. (Principal Investigator)

1981-01-01

A technique is presented which estimates pan evaporation from the commonly observed values of daily maximum and minimum air temperatures. These two variables are transformed to saturation vapor pressure equivalents which are used in a simple linear regression model. The model provides reasonably accurate estimates of pan evaporation rates over a large geographic area. The derived evaporation algorithm is combined with precipitation to obtain a simple moisture variable. A hypothetical medium with a capacity of 8 inches of water is initialized at 4 inches. The medium behaves like a sponge: it absorbs all incident precipitation, with runoff or drainage occurring only after it is saturated. Water is lost from this simple system through evaporation just as from a Class A pan, but at a rate proportional to its degree of saturation. The contents of the sponge is a moisture index calculated from only the maximum and minium temperatures and precipitation.

Evaporation and air-stripping to assess and reduce ethanolamines toxicity in oily wastewater.

PubMed

Libralato, G; Ghirardini, A Volpi; Avezzù, F

2008-05-30

Toxicity from industrial oily wastewater remains a problem even after conventional activated sludge treatment process, because of the persistence of some toxicant compounds. This work verified the removal efficiency of organic and inorganic pollutants and the effects of evaporation and air-stripping techniques on oily wastewater toxicity reduction. In a lab-scale plant, a vacuum evaporation procedure at three different temperatures and an air-stripping stage were tested on oily wastewater. Toxicity reduction/removal was observed at each treatment step via Microtox bioassay. A case study monitoring real scale evaporation was also done in a full-size wastewater treatment plant (WWTP). To implement part of a general project of toxicity reduction evaluation, additional investigations took into account the monoethanolamine (MEA), diethanolamine (DEA) and triethanolamine (TEA) role in toxicity definition after the evaporation phase, both as pure substances and mixtures. Only MEA and TEA appeared to contribute towards effluent toxicity.

Static, Mixed-Array Total Evaporation for Improved Quantitation of Plutonium Minor Isotopes in Small Samples

NASA Astrophysics Data System (ADS)

Stanley, F. E.; Byerly, Benjamin L.; Thomas, Mariam R.; Spencer, Khalil J.

2016-06-01

Actinide isotope measurements are a critical signature capability in the modern nuclear forensics "toolbox", especially when interrogating anthropogenic constituents in real-world scenarios. Unfortunately, established methodologies, such as traditional total evaporation via thermal ionization mass spectrometry, struggle to confidently measure low abundance isotope ratios (<10-6) within already limited quantities of sample. Herein, we investigate the application of static, mixed array total evaporation techniques as a straightforward means of improving plutonium minor isotope measurements, which have been resistant to enhancement in recent years because of elevated radiologic concerns. Results are presented for small sample (~20 ng) applications involving a well-known plutonium isotope reference material, CRM-126a, and compared with traditional total evaporation methods.

Fine structure of the vapor field in evaporating dense sprays

NASA Astrophysics Data System (ADS)

Villermaux, Emmanuel; Moutte, Alexandre; Amielh, Muriel; Meunier, Patrice

2017-11-01

Making use of an original technique which permits the simultaneous measurement of both the displacement field of evaporating droplets in a spray, and of their vapor, we investigate the relevance of a scenario introduced earlier to describe the evaporation dynamics of dense sprays. A plume of dense acetone droplets evaporating in air is studied, for which the stirring field is measured by particle image velocimetry of the droplets, and the vapor field is imaged quantitatively by laser-induced fluorescence. We show, thanks to these unique in situ measurements, that the spray boundary with the diluting environment is slaved to the dynamics of its saturating vapor concentration field, whose structure is analyzed for different well defined local flow topologies.

Static, Mixed-Array Total Evaporation for Improved Quantitation of Plutonium Minor Isotopes in Small Samples.

PubMed

Stanley, F E; Byerly, Benjamin L; Thomas, Mariam R; Spencer, Khalil J

2016-06-01

Actinide isotope measurements are a critical signature capability in the modern nuclear forensics "toolbox", especially when interrogating anthropogenic constituents in real-world scenarios. Unfortunately, established methodologies, such as traditional total evaporation via thermal ionization mass spectrometry, struggle to confidently measure low abundance isotope ratios (<10(-6)) within already limited quantities of sample. Herein, we investigate the application of static, mixed array total evaporation techniques as a straightforward means of improving plutonium minor isotope measurements, which have been resistant to enhancement in recent years because of elevated radiologic concerns. Results are presented for small sample (~20 ng) applications involving a well-known plutonium isotope reference material, CRM-126a, and compared with traditional total evaporation methods. Graphical Abstract ᅟ.

Transformation of eutectic emulsion to nanosuspension fabricating with solvent evaporation and ultrasonication technique

PubMed Central

Phaechamud, Thawatchai; Tuntarawongsa, Sarun

2016-01-01

Eutectic solvent can solubilize high amount of some therapeutic compounds. Volatile eutectic solvent is interesting to be used as solvent in the preparation of nanosuspension with emulsion solvent evaporation technique. The mechanism of transformation from the eutectic emulsion to nanosuspension was investigated in this study. The 30% w/w ibuprofen eutectic solution was used as the internal phase, and the external phase is composed of Tween 80 as emulsifier. Ibuprofen nanosuspension was prepared by eutectic emulsion solvent evaporating method followed with ultrasonication. During evaporation process, the ibuprofen concentration in emulsion droplets was increased leading to a drug supersaturation but did not immediately recrystallize because of low glass transition temperature (Tg) of ibuprofen. The contact angle of the internal phase on ibuprofen was apparently lower than that of the external phase at all times of evaporation, indicating that the ibuprofen crystals were preferentially wetted by the internal phase than the external phase. From calculated dewetting value ibuprofen crystallization occurred in the droplet. Crystallization of the drug was initiated with external mechanical force, and the particle size of the drug was larger due to Ostwald ripening. Cavitation force from ultrasonication minimized the ibuprofen crystals to the nanoscale. Particle size and zeta potential of formulated ibuprofen nanosuspension were 330.87±51.49 nm and −31.1±1.6 mV, respectively, and exhibited a fast dissolution. Therefore, the combination of eutectic emulsion solvent evaporation method with ultrasonication was favorable for fabricating an ibuprofen nanosuspension, and the transformation mechanism was attained successfully. PMID:27366064

Transformation of eutectic emulsion to nanosuspension fabricating with solvent evaporation and ultrasonication technique.

PubMed

Phaechamud, Thawatchai; Tuntarawongsa, Sarun

2016-01-01

Eutectic solvent can solubilize high amount of some therapeutic compounds. Volatile eutectic solvent is interesting to be used as solvent in the preparation of nanosuspension with emulsion solvent evaporation technique. The mechanism of transformation from the eutectic emulsion to nanosuspension was investigated in this study. The 30% w/w ibuprofen eutectic solution was used as the internal phase, and the external phase is composed of Tween 80 as emulsifier. Ibuprofen nanosuspension was prepared by eutectic emulsion solvent evaporating method followed with ultrasonication. During evaporation process, the ibuprofen concentration in emulsion droplets was increased leading to a drug supersaturation but did not immediately recrystallize because of low glass transition temperature (T g) of ibuprofen. The contact angle of the internal phase on ibuprofen was apparently lower than that of the external phase at all times of evaporation, indicating that the ibuprofen crystals were preferentially wetted by the internal phase than the external phase. From calculated dewetting value ibuprofen crystallization occurred in the droplet. Crystallization of the drug was initiated with external mechanical force, and the particle size of the drug was larger due to Ostwald ripening. Cavitation force from ultrasonication minimized the ibuprofen crystals to the nanoscale. Particle size and zeta potential of formulated ibuprofen nanosuspension were 330.87±51.49 nm and -31.1±1.6 mV, respectively, and exhibited a fast dissolution. Therefore, the combination of eutectic emulsion solvent evaporation method with ultrasonication was favorable for fabricating an ibuprofen nanosuspension, and the transformation mechanism was attained successfully.

Growth and antimicrobial studies of γ-glycine crystal grown using CuSO4

NASA Astrophysics Data System (ADS)

Vijayalakshmi, V.; Dhanasekaran, P.

2018-05-01

In the current work single crystals of pure and 1M of CuSO4-added glycine were grown by slow evaporation method and its optical and antimicrobial properties were studied. The Polymorph of glycine transforms from a-glycine to γ-glycine due to the incorporation of CuSO4 on glycine was affirmed by the PXRD and FTIR studies. The impact of CuSO4 on the antimicrobial action of the grown samples was deliberate by utilizing the agar diffusion method.

Striped, Ellipsoidal Particles by Controlled Assembly of Diblock Copolymers

DTIC Science & Technology

2013-04-17

morphology to a disordered bicontinuous morphology can be achieved.15,16,26−28 For poly(styrene- b -2-vinylpyridine) ( PS - b - P2VP ) materials, precise control of an...of SNPs, slow evaporation of chloroform from emulsion droplets containing PS - b - P2VP diblock copolymers resulted in solid particles with a spherical...lamellae of PS - b - P2VP and SNP necklaces decorating the outer surface could be obtained. The role of interfacially active SNPs in the morphology

Introducing ultrasonic falling film evaporator for moderate temperature evaporation enhancement.

PubMed

Dehbani, Maryam; Rahimi, Masoud

2018-04-01

In the present study, Ultrasonic Falling Film (USFF), as a novel technique has been proposed to increase the evaporation rate of moderate temperature liquid film. It is a proper method for some applications which cannot be performed at high temperature, such as foodstuff industry, due to their sensitivity to high temperatures. Evaporation rate of sodium chloride solution from an USFF on an inclined flat plate compared to that for Falling Film without ultrasonic irradiation (FF) at various temperatures was investigated. The results revealed that produced cavitation bubbles have different effects on evaporation rate at different temperatures. At lower temperatures, size fluctuation and collapse of bubbles and in consequence induced physical effects of cavitation bubbles resulted in more turbulency and evaporation rate enhancement. At higher temperatures, the behavior was different. Numerous created bubbles joined together and cover the plate surface, so not only decreased the ultrasound vibrations but also reduced the evaporation rate in comparison with FF. The highest evaporation rate enhancement of 353% was obtained at 40 °C at the lowest Reynolds number of 250. In addition, the results reveal that at temperature of 40 °C, USFF has the highest efficiency compared to FF. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparison of the properties of Pb thin films deposited on Nb substrate using thermal evaporation and pulsed laser deposition techniques

NASA Astrophysics Data System (ADS)

Perrone, A.; Gontad, F.; Lorusso, A.; Di Giulio, M.; Broitman, E.; Ferrario, M.

2013-11-01

Pb thin films were prepared at room temperature and in high vacuum by thermal evaporation and pulsed laser deposition techniques. Films deposited by both the techniques were investigated by scanning electron microscopy to determine their surface topology. The structure of the films was studied by X-ray diffraction in θ-2θ geometry. The photoelectron performances in terms of quantum efficiency were deduced by a high vacuum photodiode cell before and after laser cleaning procedures. Relatively high quantum efficiency (>10-5) was obtained for all the deposited films, comparable to that of corresponding bulk. Finally, film to substrate adhesion was also evaluated using the Daimler-Benz Rockwell-C adhesion test method. Weak and strong points of these two competitive techniques are illustrated and discussed.

Spin distribution of evaporation residues formed in complete and incomplete fusion in 16O+154Sm system

NASA Astrophysics Data System (ADS)

Singh, D.; Linda, Sneha B.; Giri, Pankaj K.; Mahato, Amritraj; Tripathi, R.; Kumar, Harish; Afzal Ansari, M.; Sathik, N. P. M.; Ali, Rahbar; Kumar, Rakesh; Muralithar, S.; Singh, R. P.

2017-11-01

Spin distributions for several evaporation residues populated in the 16O+154Sm system have been measured at projectile energy ≈ 6.2 MeV/A by using the charged particle-γ-coincidence technique. The measured spin distributions of the evaporation residues populated through incomplete fusion associated with 'fast' α and 2α-emission channels are found to be entirely different from fusion-evaporation channels. It is observed that the mean input angular momentum for the evaporation residues formed in incomplete fusion channel is relatively higher than that observed for evaporation residues in complete fusion channels. The feeding intensity profile of evaporation residues populated through complete fusion and incomplete fusion have also been studied. The incomplete fusion channels are found to have narrow range feeding only for high spin states, while complete fusion channels are strongly fed over a broad spin range and widely populated. Comparison of present results with earlier data suggests that the mean input angular momentum values are relatively smaller for spherical target than that of deformed target using the same projectile and incident energy highlighting the role of target deformation in incomplete fusion dynamics.

The relationship between air layers and evaporative resistance of male Chinese ethnic clothing.

PubMed

Wang, Faming; Peng, Hui; Shi, Wen

2016-09-01

In this study, the air layer distribution and evaporative resistances of 39 sets of male Chinese ethnic clothing were investigated using a sweating thermal manikin and the three-dimensional (3D) body scanning technique. Relationships between the evaporative resistance and air layers (i.e., air gap thickness and air volume) were explored. The results demonstrated that the clothing total evaporative resistance increases with the increasing air gap size/air volume, but the rate of increase gradually decreases as the mean air gap size or the total air volume becomes larger. The clothing total evaporative resistance reaches its maximum when the average air gap size and the total air volume are 41.6 mm and 69.9 dm(3), respectively. Similar general trends were also found between local mean air gap size and clothing local evaporative resistance at different body parts. However, different body parts show varied rates of increase and decrease in the local evaporative resistance. The research findings provide a comprehensive database for predicting overall and local human thermal comfort while wearing male Chinese ethnic clothing. Copyright © 2016 Elsevier Ltd. All rights reserved.

Evaporation kinetics of Mg2SiO4 crystals and melts from molecular dynamics simulations

NASA Technical Reports Server (NTRS)

Kubicki, J. D.; Stolper, E. M.

1993-01-01

Computer simulations based on the molecular dynamics (MD) technique were used to study the mechanisms and kinetics of free evaporation from crystalline and molten forsterite (i.e., Mg2SiO4) on an atomic level. The interatomic potential employed for these simulations reproduces the energetics of bonding in forsterite and in gas-phase MgO and SiO2 reasonably accurately. Results of the simulation include predicted evaporation rates, diffusion rates, and reaction mechanisms for Mg2SiO4(s or l) yields 2Mg(g) + 20(g) + SiO2(g).

The Synthesis of Calcium Salt from Brine Water by Partial Evaporation and Chemical Precipitation

NASA Astrophysics Data System (ADS)

Lalasari, L. H.; Widowati, M. K.; Natasha, N. C.; Sulistiyono, E.; Prasetyo, A. B.

2017-02-01

In this study would be investigated the effects of partial evaporation and chemical precipitation in the formation of calcium salt from brine water resources. The chemical reagents used in the study was oxalate acid (C2H2O4), ammonium carbonate (NH4)2CO3) and ammonium hydroxide (NH4OH) with reagent concentration of 2 N, respectively. The procedure was 10 liters brine water evaporated until 20% volume and continued with filtration process to separate brine water filtrate from residue (salt). Salt resulted from evaporation process was characterized by Scanning Electron Microscopy (SEM), X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD) techniques. Filtrate then was reacted with C2H2O4, (NH4)2CO3 and NH4OH reagents to get salt products in atmospheric condition and variation ratio volume brine water/chemicals (v/v) [10/1; 10/5; 10/10; 10/20; 10/30; 10:50; 20/1; 20/5; 20/10; 20/20; 20/30; 20:50]. The salt product than were filtered, dried, measured weights and finally characterized by SEM/EDS and XRD techniques. The result of experiment showed the chemical composition of brine water from Tirta Sanita, Bogor was 28.87% Na, 9.17% Mg, 2.94% Ca, 22.33% O, 0.71% Sr, 30.02% Cl, 1.51% Si, 1.23% K, 0.55% S, 1.31% Al. The chemical composition of salt resulted by partial evaporation was 53.02% Ca, 28.93%O, 9.50% Na, 2.10% Mg, 1.53% Sr, 1.20% Cl, 1.10% Si, 0.63% K, 0.40% S, 0.39% Al. The salt resulted by total evaporation was indicated namely as NaCl. Whereas salt resulted by partial evaporation was CaCO3 with a purity of 90 % from High Score Plus analysis. In the experiment by chemical precipitation was reported that the reagents of ammonium carbonate were more reactive for synthesizing calcium salt from brine water compared to reagents of oxalate acid and ammonium hydroxide. The salts precipitated by NH4OH, (NH4)2CO3, and H2C2O4 reagents were indicated as NaCl, CaCO3 and CaC2O4.H2O, respectively. The techniques of partial evaporation until 20% volume sample of brine water and chemical precipitation using (NH4)2CO3 reagent are recommended in the synthesis of calcium salts from brine water because are simple, flexible and economical.

A High Performance Impedance-based Platform for Evaporation Rate Detection.

PubMed

Chou, Wei-Lung; Lee, Pee-Yew; Chen, Cheng-You; Lin, Yu-Hsin; Lin, Yung-Sheng

2016-10-17

This paper describes the method of a novel impedance-based platform for the detection of the evaporation rate. The model compound hyaluronic acid was employed here for demonstration purposes. Multiple evaporation tests on the model compound as a humectant with various concentrations in solutions were conducted for comparison purposes. A conventional weight loss approach is known as the most straightforward, but time-consuming, measurement technique for evaporation rate detection. Yet, a clear disadvantage is that a large volume of sample is required and multiple sample tests cannot be conducted at the same time. For the first time in literature, an electrical impedance sensing chip is successfully applied to a real-time evaporation investigation in a time sharing, continuous and automatic manner. Moreover, as little as 0.5 ml of test samples is required in this impedance-based apparatus, and a large impedance variation is demonstrated among various dilute solutions. The proposed high-sensitivity and fast-response impedance sensing system is found to outperform a conventional weight loss approach in terms of evaporation rate detection.

Static, mixed-array total evaporation for improved quantitation of plutonium minor isotopes in small samples

DOE PAGES

Stanley, F. E.; Byerly, Benjamin L.; Thomas, Mariam R.; ...

2016-03-31

Actinide isotope measurements are a critical signature capability in the modern nuclear forensics “toolbox”, especially when interrogating anthropogenic constituents in real-world scenarios. Unfortunately, established methodologies, such as traditional total evaporation via thermal ionization mass spectrometry, struggle to confidently measure low abundance isotope ratios (<10 -6) within already limited quantities of sample. Herein, we investigate the application of static, mixed array total evaporation techniques as a straightforward means of improving plutonium minor isotope measurements, which have been resistant to enhancement in recent years because of elevated radiologic concerns. Furthermore, results are presented for small sample (~20 ng) applications involving a well-knownmore » plutonium isotope reference material, CRM-126a, and compared with traditional total evaporation methods.« less

Growth, spectral, optical, thermal, and mechanical behaviour of an organic single crystal: Quinolinium 2-carboxy 6-nitrophthalate monohydrate

NASA Astrophysics Data System (ADS)

Mohana, J.; Ahila, G.; Bharathi, M. Divya; Anbalagan, G.

2016-09-01

Organic single crystals of quinolinium 2-carboxy 6-nitrophthalate monohydrate (QN) were grown by slow evaporation solution growth technique using ethanol and water as a mixed solvent. X-ray powder diffraction analysis revealed that the crystal belongs to the monoclinic crystal system with space group of P21/c. The functional groups present in the crystallized material confirmed its molecular structure. The optical transparency range and the lower cutoff wavelength were identified from the UV-vis spectrum. The optical constants were determined by UV-visible transmission spectrum at normal incidence, measured over the 200-700 nm spectral range. The dispersion of the refractive index was discussed in terms of the single-oscillator Wemple and DiDomenico model. The calculated HOMO and LUMO energies show that the charge transfer occur within the molecule. Electronic excitation properties were discussed within the framework of two level model on the basis of an orbital analysis. The nonlinear optical absorption coefficient (β) and nonlinear refraction (n2) of QN was measured by Z-scan technique and reported here. Thermal stability of QN was determined using TGA/DSC curves. Vicker's microhardness studies were carried out on the (1 1 ̅0) plane to understand the mechanical properties of the grown crystal. The microhardness measurements showed a Vickers hardness value as 18.4 kg/mm2 which is comparable to well-known organic crystal, urea.

Bulk crystal growth and their effective third order nonlinear optical properties of 2-(4-fluorobenzylidene) malononitrile (FBM) single crystal

NASA Astrophysics Data System (ADS)

Priyadharshini, A.; Kalainathan, S.

2018-04-01

2-(4-fluorobenzylidene) malononitrile (FBM), an organic third order nonlinear (TONLO) single crystal with the dimensions of 32 × 7 × 11 mm3, has been successfully grown in acetone solution by slow evaporation technique at 35 °C. The crystal system (triclinic), space group (P-1) and crystalline purity of the titular crystal were measured by single crystal and powder X-ray diffraction, respectively. The molecular weight and the multiple functional groups of the FBM material were confirmed through the mass and FT-IR spectral analysis. UV-Vis-NIR spectral study enroles that the FBM crystal exhibits excellent transparency (83%) in the entire visible and near infra-red region with a wide bandgap 2.90 eV. The low dielectric constant (εr) value of FBM crystal is appreciable for microelectronics industry applications. Thermal stability and melting point (130.09 °C) were ascertained by TGA-DSC analysis. The laser-induced surface damage threshold (LDT) value of FBM specimen is found to be 2.14 GW/cm2, it is fairly good compared to other reported NLO crystals. The third - order nonlinear optical character of the FBM crystal was confirmed through the typical single beam Z-scan technique. All these finding authorized that the organic crystal of FBM is favorably suitable for NLO applications.

Growth and characterization of an organic single crystal: 2-[2-(4-Diethylamino-phenyl)-vinyl]-1-methyl-pyridinium iodide

NASA Astrophysics Data System (ADS)

Senthil, K.; Kalainathan, S.; Ruban Kumar, A.

Optically transparent crystal of the organic salt DEASI (2-[2-(4-Diethylamino-phenyl)-vinyl]-1-methyl-pyridinium iodide) has been synthesized by using knoevenagel condensation reaction method. The synthesized material has been purified by successfully recrystallization process. Single crystals of DEASI have been grown by slow evaporation technique at room temperature. The solubility of the title material has been determined at different temperature in acetonitrile/methanol mixture. The cell parameters and crystallinity of the title crystal were determined by single crystal XRD. The powder diffraction was carried out to study the reflection plane of the grown crystal and diffraction peaks were indexed. The presence of different functional groups in the crystal was confirmed by Fourier transform infrared (FTIR) analysis. 1H NMR spectrum was recorded to confirm the presence of hydrogen nuclei in the synthesized material. The optical property of the title crystal was studied by UV-Vis-NIR spectroscopic analysis. The melting point and thermal property of DEASI were studied using TGA/DSC technique. The Vicker’s hardness (Hv) was carried out to know the category. The dielectric constant and dielectric loss of the compound decreases with an increase in frequencies. Chemical etching studies showed that the DEASI grows in the two dimensional growth mechanisms. The Kurtz-Perry powder second harmonic generation (SHG) test has done for title crystal.

Crucial role of molecular planarity on the second order nonlinear optical property of pyridine based chalcone single crystals

NASA Astrophysics Data System (ADS)

Menezes, Anthoni Praveen; Jayarama, A.; Ng, Seik Weng

2015-05-01

An efficient nonlinear optical material 2E-3-(4-bromophenyl)-1-(pyridin-3-yl) prop-2-en-1-one (BPP) was synthesized and single crystals were grown using slow evaporation solution growth technique at room temperature. Grown crystal had prismatic morphology and its structure was confirmed by various spectroscopic studies, elemental analysis, and single crystal X-ray diffraction (XRD) technique. The single crystal XRD of the crystal showed that BPP crystallizes in monoclinic system with noncentrosymmetric space group P21 and the cell parameters are a = 5.6428(7) Å, b = 3.8637(6) Å, c = 26.411(2) Å, β = 97.568(11) deg and v = 575.82(12) Å3. The UV-Visible spectrum reveals that the crystal is optically transparent and has high optical energy band gap of 3.1 eV. The powder second harmonic generation efficiency (SHG) of BPP is 6.8 times that of KDP. From thermal analysis it is found that the crystal melts at 139 °C and decomposes at 264 °C. High optical transparency down to blue region, higher powder SHG efficiency and better thermal stability than that of urea makes this chalcone derivative a promising candidate for SHG applications. Furthermore, effect of molecular planarity on SHG efficiency and role of pyridine ring adjacent to carbonyl group in forming noncentrosymmetric crystal systems of chalcone family is also discussed.

Investigations on structural and photoluminescence mechanism of cerium doped L-Histidine hydrochloride mono hydrate single crystals for optical applications

NASA Astrophysics Data System (ADS)

Rajyalakshmi, S.; Ramachandra Rao, K.; Brahmaji, B.; Samatha, K.; Visweswara Rao, T. K.; Ramakrishna, Y.

2017-02-01

Semi organic nonlinear optical material of Ce3+ ion added L-Histidine hydrochloride monohydrate (LHHC) crystals have been grown successfully by the slow evaporation solution technique (SEST) as well as Sankaranarayanan-Ramasamy (SR) technique. Unit cell data have been measured from the single crystal X-ray diffraction analysis and High resolution X-ray diffraction analysis (HRXRD) study shows relatively a good crystalline perfection. Fourier transform infra-red spectroscopy (FTIR) spectra indicates that the Ce3+ ion is coordinated with carboxylate group of grown crystal. The lower UV-cutoff wavelength of the incorporation of Ce3+ ion in LHHC is 240 nm. The incorporation of Ce3+ ion in the crystal lattice was observed by energy dispersive X-ray analysis (EDAX). The nonlinear optical (NLO) efficiency of SR-grown crystal is 3.7 times greater with respect to potassium dihydrogen phosphate (KDP). We report first-time the photoluminescence (PL) mechanism of emission spectrum, which shows broad band located at 350 nm corresponding to 5d → 4f transition of Ce3+ ion and excited by 250 nm wavelength. The excitation spectrum shows a band at 258 nm due to the 4f → 5d transition of Ce3+ ion. The nature of decay curve of the grown crystal is bi-exponential with a long life time of τ2 is 8.8270 μs.

Construction of vacuum system for Tristan accumulation ring

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

Ishimaru, H.; Horikoshi, G.; Kobayashi, M.

1983-08-01

An all aluminum-alloy vacuum system for the TRISTAN accumulation ring is now under construction. Aluminum and aluminum alloys are preferred materials for ultrahigh vacuum systems of large electron storage rings because of their good thermal conductivity, extremely low outgassing rate, and low residual radioactivity. Vacuum beam chambers for the dipole and quadrupole magnets are extruded using porthole dies. The aluminum alloy 6063-T6 provides superior performance in extrusion. For ultrahigh vacuum performance, a special extrusion technique is applied which, along with the outgassing procedure used, is described in detail. Aluminum alloy 3004 seamless elliptical bellows are inserted between the dipole andmore » quadrupole magnet chambers. These bellows are produced by the hydraulic forming of a seamless tube. The seamless bellows and the beam chambers are joined by fully automatic welding. The ceramic chambers for the kicker magnets, the fast bump magnets, and the slow beam intensity monitor are inserted in the aluminum alloy beam chambers. The ceramic chamber (98% alumina) and elliptical bellows are brazed with brazing sheets (4003-3003-4003) in a vacuum furnace. The brazing technique is described. The inner surface of the ceramic chamber is coated with a TiMo alloy by vacuum evaporation to permit a smooth flow of the RF wall current. Other suitable aluminum alloy components, including fittings, feedthroughs, gauges, optical windows, sputter ion pumps, turbomolecular pumps, and valves have been developed; their fabrication is described.« less

Growth and characterization of an organic single crystal: 2-[2-(4-diethylamino-phenyl)-vinyl]-1-methyl-pyridinium iodide.

PubMed

Senthil, K; Kalainathan, S; Ruban Kumar, A

2014-05-05

Optically transparent crystal of the organic salt DEASI (2-[2-(4-Diethylamino-phenyl)-vinyl]-1-methyl-pyridinium iodide) has been synthesized by using knoevenagel condensation reaction method. The synthesized material has been purified by successfully recrystallization process. Single crystals of DEASI have been grown by slow evaporation technique at room temperature. The solubility of the title material has been determined at different temperature in acetonitrile/methanol mixture. The cell parameters and crystallinity of the title crystal were determined by single crystal XRD. The powder diffraction was carried out to study the reflection plane of the grown crystal and diffraction peaks were indexed. The presence of different functional groups in the crystal was confirmed by Fourier transform infrared (FTIR) analysis. (1)H NMR spectrum was recorded to confirm the presence of hydrogen nuclei in the synthesized material. The optical property of the title crystal was studied by UV-Vis-NIR spectroscopic analysis. The melting point and thermal property of DEASI were studied using TGA/DSC technique. The Vicker's hardness (Hv) was carried out to know the category. The dielectric constant and dielectric loss of the compound decreases with an increase in frequencies. Chemical etching studies showed that the DEASI grows in the two dimensional growth mechanisms. The Kurtz-Perry powder second harmonic generation (SHG) test has done for title crystal. Copyright © 2014 Elsevier B.V. All rights reserved.

Combustion Studies of Acoustically Suspended Liquid Droplets.

DTIC Science & Technology

1988-03-01

34, 2 1 02 J Acoustic Levitation .’ ABSTRACT (Continue on reverse if necessary and identify by block number) piezoelectrically driven ultrasonic resonator...was developed and tested in this study. The device was used to levitate liquid fuel droplets for evaporation measurements and ignition :tudies. The... levitation technique may hold some promise for onducting non-combustion related droplet measurements, for example evaporation tests, but wIthout further

Formation of thin film like assembly of exfoliated C3N4 nanoflakes by solvent non-evaporative method using centrifuge

NASA Astrophysics Data System (ADS)

Tejasvi, Ravi; Basu, Suddhasatwa

2017-12-01

A simple method for depositing a thin film of nanomaterial on a substrate using centrifugation technique has been developed, whereby solvent evaporation is prevented and solvent reuse is possible. The centrifuge technique of deposition yields uniform, smooth thin film irrespective of substrate surface texture. The deposited TiO2/eC3N4 film studied, through field emission scanning electron microscope, atomic force microscope, and optical surface profilometer, shows variation in surface roughness on the basis of centrifugation speeds. Initially film coverage improves and surface roughness decreases with the increase in rpm of the centrifuge and the surface roughness slightly increases with further increase in rpm. The photoelectrochemical studies of TiO2/eC3N4 films suggest that the centrifuge technique forms better heterojunctions compared to that by spin coating technique leading to enhanced photoelectrochemical water splitting.

Characterization of aroma compounds in apple cider using solvent-assisted flavor evaporation and headspace solid-phase microextraction.

PubMed

Xu, Yan; Fan, Wenlai; Qian, Michael C

2007-04-18

The aroma-active compounds in two apple ciders were identified using gas chromatography-olfactometry (GC-O) and GC-mass spectrometry (MS) techniques. The volatile compounds were extracted using solvent-assisted flavor evaporation (SAFE) and headspace solid-phase microextraction (HS-SPME). On the basis of odor intensity, the most important aroma compounds in the two apple cider samples were 2-phenylethanol, butanoic acid, octanoic acid, 2-methylbutanoic acid, 2-phenylethyl acetate, ethyl 2-methylbutanoate, ethyl butanoate, ethyl hexanoate, 4-ethylguaiacol, eugenol, and 4-vinylphenol. Sulfur-containing compounds, terpene derivatives, and lactones were also detected in ciders. Although most of the aroma compounds were common in both ciders, the aroma intensities were different. Comparison of extraction techniques showed that the SAFE technique had a higher recovery for acids and hydroxy-containing compounds, whereas the HS-SPME technique had a higher recovery for esters and highly volatile compounds.

Micro to Nanoscale Engineering of Surface Precipitates Using Reconfigurable Contact Lines.

PubMed

Kabi, Prasenjit; Chaudhuri, Swetaprovo; Basu, Saptarshi

2018-02-06

Nanoscale engineering has traditionally adopted the chemical route of synthesis or optochemical techniques such as lithography requiring large process times, expensive equipment, and an inert environment. Directed self-assembly using evaporation of nanocolloidal droplet can be a potential low-cost alternative across various industries ranging from semiconductors to biomedical systems. It is relatively simple to scale and reorient the evaporation-driven internal flow field in an evaporating droplet which can direct dispersed matter into functional agglomerates. The resulting functional precipitates not only exhibit macroscopically discernible changes but also nanoscopic variations in the particulate assembly. Thus, the evaporating droplet forms an autonomous system for nanoscale engineering without the need for external resources. In this article, an indigenous technique of interfacial re-engineering, which is both simple and inexpensive to implement, is developed. Such re-engineering widens the horizon for surface patterning previously limited by the fixed nature of the droplet interface. It involves handprinting hydrophobic lines on a hydrophilic substrate to form a confinement of any selected geometry using a simple document stamp. Droplets cast into such confinements get modulated into a variety of shapes. The droplet shapes control the contact line behavior, evaporation dynamics, and complex internal flow pattern. By exploiting the dynamic interplay among these variables, we could control the deposit's macro- as well as nanoscale assembly not possible with simple circular droplets. We provide a detailed mechanism of the coupling at various length scales enabling a predictive capability in custom engineering, particularly useful in nanoscale applications such as photonic crystals.

Direct measurements of the optical cross sections and refractive indices of individual volatile and hygroscopic aerosol particles.

PubMed

Mason, B J; Cotterell, M I; Preston, T C; Orr-Ewing, A J; Reid, J P

2015-06-04

We present measurements of the evolving extinction cross sections of individual aerosol particles (spanning 700-2500 nm in radius) during the evaporation of volatile components or hygroscopic growth using a combination of a single particle trap formed from a Bessel light beam and cavity ring-down spectroscopy. For single component organic aerosol droplets of 1,2,6-hexanetriol, polyethylene glycol 400, and glycerol, the slow evaporation of the organic component (over time scales of 1000 to 10,000 s) leads to a time-varying size and extinction cross section that can be used to estimate the refractive index of the droplet. Measurements on binary aqueous-inorganic aerosol droplets containing one of the inorganic solutes ammonium bisulfate, ammonium sulfate, sodium nitrate, or sodium chloride (over time scales of 1000 to 15,000 s) under conditions of changing relative humidity show that extinction cross-section measurements are consistent with expectations from accepted models for the variation in droplet refractive index with hygroscopic growth. In addition, we use these systems to establish an experimental protocol for future single particle extinction measurements. The advantages of mapping out the evolving light extinction cross-section of an individual particle over extended time frames accompanied by hygroscopic cycling or component evaporation are discussed.

Modeling Pan Evaporation for Kuwait by Multiple Linear Regression

PubMed Central

Almedeij, Jaber

2012-01-01

Evaporation is an important parameter for many projects related to hydrology and water resources systems. This paper constitutes the first study conducted in Kuwait to obtain empirical relations for the estimation of daily and monthly pan evaporation as functions of available meteorological data of temperature, relative humidity, and wind speed. The data used here for the modeling are daily measurements of substantial continuity coverage, within a period of 17 years between January 1993 and December 2009, which can be considered representative of the desert climate of the urban zone of the country. Multiple linear regression technique is used with a procedure of variable selection for fitting the best model forms. The correlations of evaporation with temperature and relative humidity are also transformed in order to linearize the existing curvilinear patterns of the data by using power and exponential functions, respectively. The evaporation models suggested with the best variable combinations were shown to produce results that are in a reasonable agreement with observation values. PMID:23226984

2017 Report for New LANL Physical Vapor Deposition Capability

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

Roman, Audrey Rae; Zhao, Xinxin; Bond, Evelyn M.

There is an urgent need at LANL to achieve uniform, thin film actinide targets that are essential for nuclear physics experiments. The target preparation work is currently performed externally by Professor Walter Loveland at Oregon State University, who has made various evaporated actinide targets such as Th and U for use on several nuclear physics measurements at LANSCE. We are developing a vapor deposition capability, with the goal of evaporating Th and U in the Actinide Research Facility (ARF) at TA-48. In the future we plan to expand this work to evaporating transuranic elements, such as Pu. The ARF ismore » the optimal location for evaporating actinides because this lab is specifically dedicated to actinide research. There are numerous instruments in the ARF that can be used to provide detailed characterization of the evaporated thin films such as: Table top Scanning Electron Microscope, In-situ X-Ray Diffraction, and 3D Raman spectroscopy. These techniques have the ability to determine the uniformity, surface characterization, and composition of the deposits.« less

Transparent arrays of silver nanowire rings driven by evaporation of sessile droplets

NASA Astrophysics Data System (ADS)

Wang, Xiaofeng; Kang, Giho; Seong, Baekhoon; Chae, Illkyeong; Teguh Yudistira, Hadi; Lee, Hyungdong; Kim, Hyunggun; Byun, Doyoung

2017-11-01

A coffee-ring pattern can be yielded on the three-phase contact line following evaporation of sessile droplets with suspended insoluble solutes, such as particles, DNA molecules, and mammalian cells. The formation of such coffee-ring, together with their suppression has been applied in printing and coating technologies. We present here an experimental study on the assembly of silver nanowires inside an evaporating droplet of a colloidal suspension. The effects of nanowire length and concentration on coffee-ring formation of the colloidal suspension were investigated. Several sizes of NWs with an aspect ratio between 50 and 1000 were systematically investigated to fabricate coffee-ring patterns. Larger droplets containing shorter nanowires formed clearer ring deposits after evaporation. An order-to-disorder transition of the nanowires’ alignment was found inside the rings. A printing technique with the evaporation process enabled fabrication of arrays of silver nanowire rings. We could manipulate the patterns silver nanowire rings, which might be applied to the transparent and flexible electrode.

Treatment of a waste oil-in-water emulsion from a copper-rolling process by ultrafiltration and vacuum evaporation.

PubMed

Gutiérrez, Gemma; Lobo, Alberto; Benito, José M; Coca, José; Pazos, Carmen

2011-01-30

A process is proposed for the treatment of a waste oil-in-water (O/W) emulsion generated in an industrial copper-rolling operation. The use of demulsifier agents improves the subsequent treatment by techniques such as ultrafiltration (UF) or evaporation. The effluent COD is reduced up to 50% when the O/W emulsion is treated by UF using a flat 30 nm TiO(2) ceramic membrane (ΔP = 0.1 MPa) and up to 70% when it is treated by vacuum evaporation, after an emulsion destabilization pretreatment in both cases. Increases in the UF permeate flux and in the evaporation rate are observed when a chemical demulsifier is used in the pretreatment step. A combined process consisting of destabilization/settling, UF, and vacuum evaporation can yield a very high-quality aqueous effluent that could be used for process cooling or emulsion reformulation. Copyright © 2010 Elsevier B.V. All rights reserved.

Micromachined evaporators for AMTEC cells

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

Izenson, M.G.; Crowley, C.J.

1996-12-31

To achieve high cell efficiency and reliability, the capillary pumping system for Alkali Metal Thermal to Electric Conversion (AMTEC) must have three key characteristics: (1) very small pores to achieve a high capillary pumping head, (2) high permeability for the flow of liquid sodium to minimize internal losses, and (3) be made from a material that is exceptionally stable at high temperatures in a sodium environment. The authors have developed micromachining techniques to manufacture high performance evaporators for AMTEC cells. The evaporators have been fabricated from stainless steel, molybdenum, and a niobium alloy (Nb-1Zr). The regular, micromachined structure leads tomore » very high capillary pumping head with high permeability for liquid flow. Data from tests performed with common fluids at room temperature characterize the capillary pumping head and permeability of these structures. Three micromachined evaporators have been built into AMTEC cells and operated at temperatures up to 1,100 K. Results from these tests confirm the excellent pumping capabilities of the micromachined evaporators.« less

Conversion of lanthanide glutarate chlorides with interstitial THF into lanthanide glutarates with unprecedented topologies

DOE PAGES

Zehnder, Ralph A.; Jenkins, James; Zeller, Matthias; ...

2017-11-26

Here, using slow diffusion methods at room temperature (RT), we obtained four isomorphous lanthanide glutarate chlorides, accommodating interstitial THF and water molecules, [Ln 2(Glut) 2Cl 2(H 2O) 8]·2H 2O·THF, with Ln = La , Ce, Pr, Nd. They assemble as 3-dimensional (3D) lanthanide (Ln) coordination polymers with LnO 10 coordination polyhedra. Their topology was elucidated to be a 4-coordinated sql net. slowly dissolve in water liberating the entrapped THF molecules and reassemble as regular Ln-glutarate hydrates when the solution is deprived of THF and water by slow evaporation. The new products crystallize as [Ln 2(Glut) 3(H 2O) 3]·5H 2O, withmore » Ln = La, Ce, Pr, and [Nd 2(Glut) 3(H 2O) 2]·3.5H 2O.« less

Conversion of lanthanide glutarate chlorides with interstitial THF into lanthanide glutarates with unprecedented topologies

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

Zehnder, Ralph A.; Jenkins, James; Zeller, Matthias

Here, using slow diffusion methods at room temperature (RT), we obtained four isomorphous lanthanide glutarate chlorides, accommodating interstitial THF and water molecules, [Ln 2(Glut) 2Cl 2(H 2O) 8]·2H 2O·THF, with Ln = La , Ce, Pr, Nd. They assemble as 3-dimensional (3D) lanthanide (Ln) coordination polymers with LnO 10 coordination polyhedra. Their topology was elucidated to be a 4-coordinated sql net. slowly dissolve in water liberating the entrapped THF molecules and reassemble as regular Ln-glutarate hydrates when the solution is deprived of THF and water by slow evaporation. The new products crystallize as [Ln 2(Glut) 3(H 2O) 3]·5H 2O, withmore » Ln = La, Ce, Pr, and [Nd 2(Glut) 3(H 2O) 2]·3.5H 2O.« less

Developing Mathematical Provisions for Assessment of Liquid Hydrocarbon Emissions in Emergency Situations

NASA Astrophysics Data System (ADS)

Zemenkova, M. Yu; Zemenkov, Yu D.; Shantarin, V. D.

2016-10-01

The paper reviews the development of methodology for calculation of hydrocarbon emissions during seepage and evaporation to monitor the reliability and safety of hydrocarbon storage and transportation. The authors have analyzed existing methods, models and techniques for assessing the amount of evaporated oil. Models used for predicting the material balance of multicomponent two-phase systems have been discussed. The results of modeling the open-air hydrocarbon evaporation from an oil spill are provided and exemplified by an emergency pit. Dependences and systems of differential equations have been obtained to assess parameters of mass transfer from the open surface of a liquid multicomponent mixture.

Structural and optical properties of electron-beam-evaporated ZnSe 1- x Te x Ternary compounds with various Te contents

NASA Astrophysics Data System (ADS)

Suthagar, J.; Suthan Kissinger, N. J.; Sharli Nath, G. M.; Perumal, K.

2014-01-01

ZnSe1- x Te x films with different tellurium (Te) contents were deposited by using an electron beam (EB) evaporation technique onto glass substrates for applications to optoelectronic devices. The structural and the optical properties of the ZnSe1- x Te x films were studied in the present work. The host material ZnSe1- x Te x , were prepared by using the physical vapor deposition method of the electron beam evaporation technique (PVD: EBE) under a pressure of 1 × 10-5 mbar. The X-ray diffractogram indicated that these alloy films had cubic structure with a strong preferential orientation of the crystallites along the (1 1 1) direction. The optical properties showed that the band gap (E g ) values varied from 2.73 to 2.41 eV as the tellurium content varied from 0.2 to 0.8. Thus the material properties can be altered and excellently controlled by controlling the system composition x.

The impact of antibacterial handsoap constituents on the dynamics of triclosan dissolution from dry sand.

PubMed

Koehler, Daniel A; Strevett, Keith A; Papelis, Charalambos; Kibbey, Tohren C G

2017-11-01

Triclosan has been widely used as an antibacterial agent in consumer and industrial products, and large quantities continue to be discharged to natural waters annually. The focus of this work was on studying the dynamics of triclosan dissolution following evaporative drying. Warm weather can cause the water in intermittent streams or the unsaturated zone to evaporate, causing nonvolatile compounds to form solid precipitates. Because dissolution of precipitates is a relatively slow process, the dynamics of dissolution following evaporation may play an important role in controlling the release of contaminants to the environment. The specific purpose of the work was to explore the effects of surfactant co-contaminants from an industrial antibiotic handsoap on the dissolution dynamics of triclosan. The work used a fiber optic-based optical cell to conduct stirred-batch dissolution experiments for sands coated with different mass loadings of triclosan. Results show that the presence of surfactants from the hand soap not only increase the apparent equilibrium solubility, but also increase the rate of approach to equilibrium. A model describing the dissolution process was developed, and was found to be consistent with experimental data. Results of the work suggest that even small solubility enhancement by surfactant co-contaminants may have a significant impact on dissolution dynamics. Because waters containing significant quantities of triclosan are also among those most likely to contain surfactant co-contaminants, it is likely that the release of triclosan to the environment following evaporation may be faster in many cases than would be predicted from experiments based on pure triclosan. Copyright © 2017 Elsevier Ltd. All rights reserved.

Laser Evaporation Studies.

DTIC Science & Technology

1987-10-01

characterized to understand the ef- dependent refractive-index, ambient sensitivity due to fects of the laser evaporation conditions on the struc- adsorption of...or Ar-coated ZnSe crystalline structure in thin films Pulsed laser-assisted dep- osition is one such emerging technique which has a unique...needed to pre% ent satura- plates of ZnSe. NaCI. GaAs. and Ge. which when used in tion of the detector arraN. ,arious combinations proided incremental

Soil water content and evaporation determined by thermal parameters obtained from ground-based and remote measurements

NASA Technical Reports Server (NTRS)

Reginato, R.; Idso, S.; Vedder, J.; Jackson, R.; Blanchard, M.; Goettelman, R.

1975-01-01

A procedure is presented for calculating 24-hour totals of evaporation from wet and drying soils. Its application requires a knowledge of the daily solar radiation, the maximum and minimum, air temperatures, moist surface albedo, and maximum and minimum surface temperatures. Tests of the technique on a bare field of Avondale loam at Phoenix, Arizona showed it to be independent of season.

Growth and characterization of pure and glycine doped cadmium thiourea sulphate (GCTS) crystals

NASA Astrophysics Data System (ADS)

Lawrence, M.; Thomas Joseph Prakash, J.

2012-06-01

The pure and glycine doped cadmium thiourea sulphate (GCTS) single crystals were grown successfully by slow evaporation method at room temperature. The concentration of dopant in the mother solution was 1 mol%. There is a change in unit cell. The Fourier transform infrared spectroscopy study confirms the incorporation of glycine into CTS crystal. The doped crystals are optically better and more transparent than the pure ones. The dopant increases the hardness value of the material. The grown crystals were also subjected to thermal and NLO studies.

Infrared and Raman spectroscopy and DFT calculations of DL amino acids: Valine and lysine hydrochloride

NASA Astrophysics Data System (ADS)

Paiva, F. M.; Batista, J. C.; Rêgo, F. S. C.; Lima, J. A.; Freire, P. T. C.; Melo, F. E. A.; Mendes Filho, J.; de Menezes, A. S.; Nogueira, C. E. S.

2017-01-01

Single crystals of DL-valine and DL-lysine hydrochloride were grown by slow evaporation method and the crystallographic structure were confirmed by X-ray diffraction experiment and Rietveld method. These two crystals have been studied by Raman spectroscopy in the 25-3600 cm-1 spectral range and by infrared spectroscopy through the interval 375-4000 cm-1 at room temperature. Experimental and theoretical vibrational spectra were compared and a complete analysis of the modes was done in terms of the Potential Energy Distribution (PED).

Development of plasma assisted thermal vapor deposition technique for high-quality thin film.

PubMed

Lee, Kang-Il; Choi, Yong Sup; Park, Hyun Jae

2016-12-01

The novel technique of Plasma-Assisted Vapor Deposition (PAVD) is developed as a new deposition method for thin metal films. The PAVD technique yields a high-quality thin film without any heating of the substrate because evaporated particles acquire energy from plasma that is confined to the inside of the evaporation source. Experiments of silver thin film deposition have been carried out in conditions of pressure lower than 10 -3 Pa. Pure silver plasma generation is verified by the measurement of the Ag-I peak using optical emission spectroscopy. A four point probe and a UV-VIS spectrophotometer are used to measure the electrical and optical properties of the silver film that is deposited by PAVD. For an ultra-thin silver film with a thickness of 6.5 nm, we obtain the result of high-performance silver film properties, including a sheet resistance <20 Ω sq -1 and a visible-range transmittance >75%. The PAVD-film properties show a low sheet resistance of 30% and the same transmittance with conventional thermal evaporation film. In the PAVD source, highly energetic particles and UV from plasma do not reach the substrate because the plasma is completely shielded by the optimized nozzle of the crucible. This new PAVD technique could be a realistic solution to improve the qualities of transparent electrodes for organic light emission device fabrication without causing damage to the organic layers.

Development of plasma assisted thermal vapor deposition technique for high-quality thin film

NASA Astrophysics Data System (ADS)

Lee, Kang-Il; Choi, Yong Sup; Park, Hyun Jae

2016-12-01

The novel technique of Plasma-Assisted Vapor Deposition (PAVD) is developed as a new deposition method for thin metal films. The PAVD technique yields a high-quality thin film without any heating of the substrate because evaporated particles acquire energy from plasma that is confined to the inside of the evaporation source. Experiments of silver thin film deposition have been carried out in conditions of pressure lower than 10-3 Pa. Pure silver plasma generation is verified by the measurement of the Ag-I peak using optical emission spectroscopy. A four point probe and a UV-VIS spectrophotometer are used to measure the electrical and optical properties of the silver film that is deposited by PAVD. For an ultra-thin silver film with a thickness of 6.5 nm, we obtain the result of high-performance silver film properties, including a sheet resistance <20 Ω sq-1 and a visible-range transmittance >75%. The PAVD-film properties show a low sheet resistance of 30% and the same transmittance with conventional thermal evaporation film. In the PAVD source, highly energetic particles and UV from plasma do not reach the substrate because the plasma is completely shielded by the optimized nozzle of the crucible. This new PAVD technique could be a realistic solution to improve the qualities of transparent electrodes for organic light emission device fabrication without causing damage to the organic layers.

Reconciling Isotopic Partitioning Estimates of Moisture Fluxes in Semi-arid Landscapes Through a New Modeling Approach for Evaporation

NASA Astrophysics Data System (ADS)

Kaushik, A.; Berkelhammer, M. B.; O'Neill, M.; Noone, D.

2017-12-01

The partitioning of land surface latent heat flux into evaporation and transpiration remains a challenging problem despite a basic understanding of the underlying mechanisms. Water isotopes are useful tracers for separating evaporation and transpiration contributions because E and T have distinct isotopic ratios. Here we use the isotope-based partitioning method at a semi-arid grassland tall-tower site in Colorado. Our results suggest that under certain conditions evaporation cannot be isotopically distinguished from transpiration without modification of existing partitioning techniques. Over a 4-year period, we measured profiles of stable oxygen and hydrogen isotope ratios of water vapor from the surface to 300 m and soil water down to 1 m along with standard meteorological fluxes. Using these data, we evaluated the contributions of rainfall, equilibration, surface water vapor exchange and sub-surface vapor diffusion to the isotopic composition of evapotranspiration (ET). Applying the standard isotopic approach to find the transpiration portion of ET (i.e., T/ET), we see a significant discrepancy compared with a method to constrain T/ET based on gross primary productivity (GPP). By evaluating the kinetic fractionation associated with soil evaporation and vapor diffusion we find that a significant proportion (58-84%) of evaporation following precipitation is non-fractionating. This is possible when water from isolated soil layers is being nearly completely evaporated. Non-fractionating evaporation looks isotopically like transpiration and therefore leads to an overestimation of T/ET. Including non-fractionating evaporation reconciles the isotope-based partitioning estimates of T/ET with the GPP method, and may explain the overestimation of T/ET from isotopes compared to other methods. Finally, we examine the application of non-fractionating evaporation to other boundary layer moisture flux processes such as rain evaporation, where complete evaporation of smaller drop pools may produce a similarly weaker kinetic effect.

Modelling non-equilibrium secondary organic aerosol formation and evaporation with the aerosol dynamics, gas- and particle-phase chemistry kinetic multilayer model ADCHAM

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

Roldin, P.; Eriksson, A. C.; Nordin, E. Z.

2014-08-11

We have developed the novel Aerosol Dynamics, gas- and particle- phase chemistry model for laboratory CHAMber studies (ADCHAM). The model combines the detailed gas phase Master Chemical Mechanism version 3.2, an aerosol dynamics and particle phase chemistry module (which considers acid catalysed oligomerization, heterogeneous oxidation reactions in the particle phase and non-ideal interactions between organic compounds, water and inorganic ions) and a kinetic multilayer module for diffusion limited transport of compounds between the gas phase, particle surface and particle bulk phase. In this article we describe and use ADCHAM to study: 1) the mass transfer limited uptake of ammonia (NH3)more » and formation of organic salts between ammonium (NH4+) and carboxylic acids (RCOOH), 2) the slow and almost particle size independent evaporation of α-pinene secondary organic aerosol (SOA) particles, and 3) the influence of chamber wall effects on the observed SOA formation in smog chambers.« less

Solitosynthesis: Cosmological evolution of non-topological solitons

NASA Technical Reports Server (NTRS)

Griest, Kim; Kolb, Edward W.

1989-01-01

The thermal creation, fusion, evaporation, and destruction of non-topological solitons (NTS) after a phase transition in the early universe is considered. By defining and following NTS statistical equilibrium and departures from it, and depending on particle physics parameters, one of three possible scenarios occurs. If reaction rates are high enough, a period of equilibrium occurs and relic abundances are determined by the freeze-out temperature. Equilibrium first drives most NTS's into their constituents (free phi particles) and then causes rapid fusion into large NTS's. If freeze-out occurs during the first phase, the NTS's are almost entirely destroyed, while if it occurs during the second phase, solitosynthesis occurs and NTS's may be cosmically relevant. For slow reaction rates the NTS's are born frozen out and have the abundance determined by the phase transition. Analytic approximations for determining the abundances are developed, and tested by numerically integrating a reaction network in an expanding universe. Unfortunately, for most of the parameter space considered, solito-destruction/evaporation occurs.

Modification of the rheological properties of screen printing ceramic paints containing gold

NASA Astrophysics Data System (ADS)

Izak, P.; Mastalska-Poplawska, J.; Lis, J.; Stempkowska, A.

2017-01-01

This work presents the results of modification of rheological properties of screen printing paints containing gold. 15 wt% glossy gold paste and 15 wt% glossy liquid gold were used as modifiers containing gold. The study showed that the gold paint for screen printing can be obtained by evaporation of the 15 wt% liquid gold and the golden luster. The compaction process of liquid gold by evaporation is slow and easy to perform in industrial conditions. The second way to adapt the 15 wt% gold ceramic paint for screen printing application depended on adding the aniseed oil and the pine oil. The course of the flow curve of the gold paste without modification indicates that it is shear thinning and shows the desired effect of thixotropy, and even anti-thixotropy, at low shear rates (<50-1 s-1). The introduction of the essential oils eliminates this phenomenon and the paste converts itself from the non-rheostable to the rheostable liquid.

Evaluation of tear evaporation from ocular surface by functional infrared thermography.

PubMed

Tan, Jen-Hong; Ng, E Y K; Acharya, U Rajendra

2010-11-01

A novel technique was developed to measure tear evaporation and monitor its variation with respect to time, for the studying of ocular physiology based on dynamic functional infrared thermography and the first law of thermodynamics using the measured ocular surface temperatures (OSTs). This is a noninvasive, noncontact temperature measuring method that is widely applied in the field of biomedicine. A simple method based on the ocular thermal data was proposed to measure the rate of tear evaporation. The OST of 60 normal subjects were recorded in the form of sequential thermal images. For each thermal sequence, the ocular region was selected and warped to a standard form. Thermal data within the regions were processed, on the basis of the first law of thermodynamics to derive the evaporation rate. For elder subjects (aged above 35), the rate was determined to be 55.82 Wm(-2) and for younger subjects, the rate was 58.9 Wm(-2). The corneal rate of evaporation in elder subjects was found statistically (p < 0.11) larger than their younger counterparts. The rate of blinking was observed to be related to the variation of evaporation rate. The authors have measured the evaporation rate on a sequence of thermographic images. A region of interest was selected at first and the same region on all the images were warped into a standard form. Calculations were performed based on the thermal data in those regions to obtain the values of interest. The authors found that the tear evaporation rate for subjects of all age groups was 57.36 +/- 12.73 Wm(-2) and the corneal tear evaporation was higher in elder subjects. The corneal rate of evaporation fluctuated in a larger magnitude in subjects who blinked more than average.

Evaporation-induced flow in an inviscid liquid line at any contact angle

NASA Astrophysics Data System (ADS)

Petsi, A. J.; Burganos, V. N.

2006-04-01

The problem of potential flow inside an evaporating liquid line, shaped as an infinitely long cylindrical segment lying on a flat surface, is considered and an analytical solution is obtained for any contact angle in (0,π) . In this way, microflow details inside linear liquid bodies evaporating on hydrophilic, hydrophobic, and strongly hydrophobic substrates can now be obtained. The mathematical formulation employs the velocity potential and stream function formulations in bipolar coordinates and the solution is obtained using the technique of Fourier transform. Both pinned and depinned contact lines are considered. The solution is applicable to any evaporation mechanism but for illustration purposes numerical results are presented here for the particular case of kinetically controlled evaporation. For hydrophilic substrates, the flow inside the evaporating liquid line is directed towards the edges for pinned contact lines, thus, promoting a coffee stain effect. The opposite flow direction is observed for depinned contact lines. However, for strongly hydrophobic substrates, flow is directed outwards for both pinned and depinned contact lines, but owing to its low magnitude compared to that on hydrophilic substrates, a craterlike colloidal deposit should be expected rather than a ringlike deposit, in agreement with experimental observations.

Free energy barriers to evaporation of water in hydrophobic confinement.

PubMed

Sharma, Sumit; Debenedetti, Pablo G

2012-11-08

We use umbrella sampling Monte Carlo and forward and reverse forward flux sampling (FFS) simulation techniques to compute the free energy barriers to evaporation of water confined between two hydrophobic surfaces separated by nanoscopic gaps, as a function of the gap width, at 1 bar and 298 K. The evaporation mechanism for small (1 × 1 nm(2)) surfaces is found to be fundamentally different from that for large (3 × 3 nm(2)) surfaces. In the latter case, the evaporation proceeds via the formation of a gap-spanning tubular cavity. The 1 × 1 nm(2) surfaces, in contrast, are too small to accommodate a stable vapor cavity. Accordingly, the associated free energy barriers correspond to the formation of a critical-sized cavity for sufficiently large confining surfaces, and to complete emptying of the gap region for small confining surfaces. The free energy barriers to evaporation were found to be of O(20kT) for 14 Å gaps, and to increase by approximately ~5kT with every 1 Å increase in the gap width. The entropy contribution to the free energy of evaporation was found to be independent of the gap width.

Effective micro-spray cooling for light-emitting diode with graphene nanoporous layers

NASA Astrophysics Data System (ADS)

Keong Lay, Kok; Yew Cheong, Brian Mun; Li Tong, Wei; Tan, Ming Kwang; Hung, Yew Mun

2017-04-01

A graphene nanoplatelet (GNP) coating is utilized as a functionalized surface in enhancing the evaporation rate of micro-spray cooling for light-emitting diodes (LEDs). In micro-spray cooling, water is atomized into micro-sized droplets to reduce the surface energy and to increase the surface area for evaporation. The GNP coating facilitates the effective filmwise evaporation through the attribute of fast water permeation. The oxygenated functional groups of GNPs provide the driving force that initiates the intercalation of water molecules through the carbon nanostructure. The water molecules slip through the frictionless passages between the hydrophobic carbon walls, resulting an effective filmwise evaporation. The enhancement of evaporation leads to an enormous temperature reduction of 61.3 °C. The performance of the LED is greatly enhanced: a maximum increase in illuminance of 25% and an extension of power rating from 9 W to 12 W can be achieved. With the application of GNP coating, the high-temperature region is eliminated while maintaining the LED surface temperature for optimal operation. This study paves the way for employing the effective hybrid spray-evaporation-nanostructure technique in the development of a compact, low-power-consumption cooling system.

4D Imaging of Salt Precipitation during Evaporation from Saline Porous Media Influenced by the Particle Size Distribution

NASA Astrophysics Data System (ADS)

Norouzi Rad, M.; Shokri, N.

2014-12-01

Understanding the physics of water evaporation from saline porous media is important in many processes such as evaporation from porous media, vegetation, plant growth, biodiversity in soil, and durability of building materials. To investigate the effect of particle size distribution on the dynamics of salt precipitation in saline porous media during evaporation, we applied X-ray micro-tomography technique. Six samples of quartz sand with different grain size distributions were used in the present study enabling us to constrain the effects of particle and pore sizes on salt precipitation patterns and dynamics. The pore size distributions were computed using the pore-scale X-ray images. The packed beds were saturated with NaCl solution of 3 Molal and the X-ray imaging was continued for one day with temporal resolution of 30 min resulting in pore scale information about the evaporation and precipitation dynamics. Our results show more precipitation at the early stage of the evaporation in the case of sand with the larger particle size due to the presence of fewer evaporation sites at the surface. The presence of more preferential evaporation sites at the surface of finer sands significantly modified the patterns and thickness of the salt crust deposited on the surface such that a thinner salt crust was formed in the case of sand with smaller particle size covering larger area at the surface as opposed to the thicker patchy crusts in samples with larger particle sizes. Our results provide new insights regarding the physics of salt precipitation in porous media during evaporation.

Combustion of bulk titanium in oxygen

NASA Technical Reports Server (NTRS)

Clark, A. F.; Moulder, J. C.; Runyan, C. C.

1975-01-01

The combustion of bulk titanium in one atmosphere oxygen is studied using laser ignition and several analytical techniques. These were high-speed color cinematography, time and space resolved spectra in the visible region, metallography (including SEM) of specimens quenched in argon gas, X-ray and chemical product analyses, and a new optical technique, the Hilbert transform method. The cinematographic application of this technique for visualizing phase objects in the combustion zone is described. The results indicate an initial vapor phase reaction immediately adjacent to the molten surface but as the oxygen uptake progresses the evaporation approaches the point of congruency and a much reduced evaporation rate. This and the accumulation of the various soluble oxides soon drive the reaction zone below the surface where gas formation causes boiling and ejection of particles. The buildup of rutile cuts off the oxygen supply and the reaction ceases.

Microjets and coated wheels: versatile tools for exploring collisions and reactions at gas-liquid interfaces.

PubMed

Faust, Jennifer A; Nathanson, Gilbert M

2016-07-07

This tutorial review describes experimental aspects of two techniques for investigating collisions and reactions at the surfaces of liquids in vacuum. These gas-liquid scattering experiments provide insights into the dynamics of interfacial processes while minimizing interference from vapor-phase collisions. We begin with a historical survey and then compare attributes of the microjet and coated-wheel techniques, developed by Manfred Faubel and John Fenn, respectively, for studies of high- and low-vapor pressure liquids in vacuum. Our objective is to highlight the strengths and shortcomings of each technique and summarize lessons we have learned in using them for scattering and evaporation experiments. We conclude by describing recent microjet studies of energy transfer between O2 and liquid hydrocarbons, HCl dissociation in salty water, and super-Maxwellian helium evaporation.

GLEAM v3: updated land evaporation and root-zone soil moisture datasets

NASA Astrophysics Data System (ADS)

Martens, Brecht; Miralles, Diego; Lievens, Hans; van der Schalie, Robin; de Jeu, Richard; Fernández-Prieto, Diego; Verhoest, Niko

2016-04-01

Evaporation determines the availability of surface water resources and the requirements for irrigation. In addition, through its impacts on the water, carbon and energy budgets, evaporation influences the occurrence of rainfall and the dynamics of air temperature. Therefore, reliable estimates of this flux at regional to global scales are of major importance for water management and meteorological forecasting of extreme events. However, the global-scale magnitude and variability of the flux, and the sensitivity of the underlying physical process to changes in environmental factors, are still poorly understood due to the limited global coverage of in situ measurements. Remote sensing techniques can help to overcome the lack of ground data. However, evaporation is not directly observable from satellite systems. As a result, recent efforts have focussed on combining the observable drivers of evaporation within process-based models. The Global Land Evaporation Amsterdam Model (GLEAM, www.gleam.eu) estimates terrestrial evaporation based on daily satellite observations of meteorological drivers of terrestrial evaporation, vegetation characteristics and soil moisture. Since the publication of the first version of the model in 2011, GLEAM has been widely applied for the study of trends in the water cycle, interactions between land and atmosphere and hydrometeorological extreme events. A third version of the GLEAM global datasets will be available from the beginning of 2016 and will be distributed using www.gleam.eu as gateway. The updated datasets include separate estimates for the different components of the evaporative flux (i.e. transpiration, bare-soil evaporation, interception loss, open-water evaporation and snow sublimation), as well as variables like the evaporative stress, potential evaporation, root-zone soil moisture and surface soil moisture. A new dataset using SMOS-based input data of surface soil moisture and vegetation optical depth will also be distributed. The most important updates in GLEAM include the revision of the soil moisture data assimilation system, the evaporative stress functions and the infiltration of rainfall. In this presentation, we will highlight the changes of the methodology and present the new datasets, their validation against in situ observations and the comparisons against alternative datasets of terrestrial evaporation, such as GLDAS-Noah, ERA-Interim and previous GLEAM datasets. Preliminary results indicate that the magnitude and the spatio-temporal variability of the evaporation estimates have been slightly improved upon previous versions of the datasets.

Dynamic model inversion techniques for breath-by-breath measurement of carbon dioxide from low bandwidth sensors.

PubMed

Sivaramakrishnan, Shyam; Rajamani, Rajesh; Johnson, Bruce D

2009-01-01

Respiratory CO(2) measurement (capnography) is an important diagnosis tool that lacks inexpensive and wearable sensors. This paper develops techniques to enable use of inexpensive but slow CO(2) sensors for breath-by-breath tracking of CO(2) concentration. This is achieved by mathematically modeling the dynamic response and using model-inversion techniques to predict input CO(2) concentration from the slow-varying output. Experiments are designed to identify model-dynamics and extract relevant model-parameters for a solidstate room monitoring CO(2) sensor. A second-order model that accounts for flow through the sensor's filter and casing is found to be accurate in describing the sensor's slow response. The resulting estimate is compared with a standard-of-care respiratory CO(2) analyzer and shown to effectively track variation in breath-by-breath CO(2) concentration. This methodology is potentially useful for measuring fast-varying inputs to any slow sensor.

Growth and characterization of Methyl 2-amino-5-bromobenzoate crystal for NLO applications

NASA Astrophysics Data System (ADS)

Parthasarathy, M.; Gopalakrishnan, R.

2012-11-01

Good quality single crystal of organic Methyl 2-amino-5-bromobenzoate (M2A5B) was grown using slow evaporation solution growth technique. The grown crystal was confirmed by single crystal X-ray diffraction. The functional groups and vibrational frequencies were identified using FT-IR and FT-Raman spectral analyses. The presence of hydrogen and carbon atoms in the grown sample was confirmed with proton and carbon NMR spectral studies. The optical energy band gap of the title compound is found to be 2.7 eV from the optical transmission spectra. The refractive indices nx, ny, and nz were found to be 1.569, 1.587 and 1.600, respectively using Brewster's angle method. The melting point of the material obtained with melting point apparatus is 74 °C. Thermal stability of the grown crystal was studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The mechanical behaviour of the grown crystal was analyzed with Vicker's microhardness tester. The particle size dependent second harmonic generation efficiency for M2A5B was evaluated by Kurtz-Perry powder method using Nd:YAG laser, which established the existence of phase matching.

Structural, optical, thermal and mechanical properties of Urea tartaric acid single crystals.

PubMed

Vinothkumar, P; Rajeswari, K; Kumar, R Mohan; Bhaskaran, A

2015-06-15

Urea tartaric acid (UT) an organic nonlinear optical (NLO) material was synthesized from aqueous solution and the crystals were grown by the slow evaporation technique. The single crystal X-ray diffraction (XRD) analysis revealed that the UT crystal belongs to the orthorhombic system. The functional groups of UT have been identified by the Fourier transform infrared spectral studies. The optical transparent window in the visible and near the IR regions was investigated. The transmittance of UT has been used to calculate the refractive index (n) as a function of the wavelength. The nonlinear optical property of the grown crystal has been confirmed by the Kurtz powder second harmonic generation test. The birefringence of the crystal was determined using a tungsten halogen lamp source. The laser induced surface damage threshold for the grown crystal was measured using the Nd:YAG laser. The anisotropic in mechanical property of the grown crystals was studied using Vicker's microhardness tester at different planes. The etch pit density of UT crystals was investigated. The thermal behavior of UT was investigated using the TG-DTA and DSC studies. Copyright © 2015 Elsevier B.V. All rights reserved.

Twisted intramolecular charge transfer investigation of semi organic L-Glutamic acid hydrochloride single crystal for organic light-emitting and optical limiting applications

NASA Astrophysics Data System (ADS)

Joy, Lija K.; George, Merin; Alex, Javeesh; Aravind, Arun; Sajan, D.; Vinitha, G.

2018-03-01

Single crystals of L-Glutamic acid hydrochloride (LGHCl) were grown by slow evaporation solution technique and good crystalline perfection was confirmed by Powder X-ray diffraction studies. The complete vibrational studies of the compound were analyzed by FT-IR, FT-Raman and UV-visible spectra combined with Normal Coordinate Analysis (NCA) following the scaled quantum mechanical force field methodology and density functional theory (DFT). Twisted Intramolecular Charge Transfer (ICT) occurs due to the presence of strong ionic intra-molecular Nsbnd H⋯O hydrogen bonding was confirmed by Hirshfeld Surface analysis. The existence of intermolecular Nsbnd H⋯Cl hydrogen bonds due to the interaction between the lone pair of oxygen with the antibonding orbital was established by NBO analysis. The Z-scan result indicated that the title molecule exhibits saturable absorption behavior. The attractive third-order nonlinear properties suggest that LGHCl can be a promising candidate for the design and development devices for optical limiting applications. LGHCL exhibits distinct emission in the blue region of the fluorescence lifetime which proves to be a potential candidate for blue- Organic light-emitting diodes (OLEDs) fabrication.

Sucrose diffusion in aqueous solution

PubMed Central

Murray, Benjamin J.

2016-01-01

The diffusion of sugar in aqueous solution is important both in nature and in technological applications, yet measurements of diffusion coefficients at low water content are scarce. We report directly measured sucrose diffusion coefficients in aqueous solution. Our technique utilises a Raman isotope tracer method to monitor the diffusion of non-deuterated and deuterated sucrose across a boundary between the two aqueous solutions. At a water activity of 0.4 (equivalent to 90 wt% sucrose) at room temperature, the diffusion coefficient of sucrose was determined to be approximately four orders of magnitude smaller than that of water in the same material. Using literature viscosity data, we show that, although inappropriate for the prediction of water diffusion, the Stokes–Einstein equation works well for predicting sucrose diffusion under the conditions studied. As well as providing information of importance to the fundamental understanding of diffusion in binary solutions, these data have technological, pharmaceutical and medical implications, for example in cryopreservation. Moreover, in the atmosphere, slow organic diffusion may have important implications for aerosol growth, chemistry and evaporation, where processes may be limited by the inability of a molecule to diffuse between the bulk and the surface of a particle. PMID:27364512

Spectroscopic investigation on structure and pH dependent Cocrystal formation between gamma-aminobutyric acid and benzoic acid

NASA Astrophysics Data System (ADS)

Du, Yong; Xue, Jiadan; Cai, Qiang; Zhang, Qi

2018-02-01

Vibrational spectroscopic methods, including terahertz absorption and Raman scattering spectroscopy, were utilized for the characterization and analysis of gamma-aminobutyric acid (GABA), benzoic acid (BA), and the corresponding GABA-BA cocrystal formation under various pH values of aqueous solution. Vibrational spectroscopic results demonstrated that the solvent GABA-BA cocrystal, similar as grinding counterpart, possessed unique characteristic features compared with that of starting parent compounds. The change of vibrational modes for GABA-BA cocrystal comparing with starting components indicates there is strong inter-molecular interaction between GABA and BA molecules during its cocrystallization process. Formation of GABA-BA cocrystal under slow solvent evaporation is impacted by the pH value of aqueous solution. Vibrational spectra indicate that the GABA-BA cocrystal could be stably formed with the solvent condition of 2.00 ≤ pH ≤ 7.00. In contrast, such cocrystallization did not occur and the cocrystal would dissociate into its parent components when the pH value of solvent is lower than 2.00. This study provides experimental benchmark to discriminate and identify the structure of cocrystal and also pH-dependent cocrystallization effect with vibrational spectroscopic techniques in solid-state pharmaceutical fields.

Growth and physicochemical properties of organometallic (DL)-trithioureatartrato-O1,O2,O3-cadmium(II) single crystals

NASA Astrophysics Data System (ADS)

Sathyamoorthy, K.; Vinothkumar, P.; Irshad Ahamed, J.; Murali Manohar, P.; Priya, M.; Liu, Jinghe

2018-04-01

Single crystals of organometallic (DL)-trithioureatartrato-O1,O2,O3-cadmium(II) (TUDLC) have been grown from methanol solution by using the slow evaporation of solvent growth technique. The lattice structure and crystalline perfection have been determined by carrying out single crystal X-ray diffraction and high resolution X-ray diffraction measurements. The grown crystal was characterized thermally and mechanically by carrying out thermo-gravimetric and micro hardness measurements. The linear and nonlinear optical characterizations were made by carrying out optical transmittance, surface laser damage threshold, particle size-dependent second harmonic generation (SHG) efficiency and photo conductivity measurements. The grown crystal was electrically characterized by carrying out frequency-dependent dielectric measurements. Chemical etching study was also carried out and the dislocation density was estimated. Results obtained in the present study indicate that the grown TUDLC crystal is optically transparent with lower cut-off wavelength 304 nm, mechanically soft, thermally stable up to 101 °C and NLO active with SHG efficiency 2.13 (in KDP unit). The grown crystal is found to have considerably large size, good crystalline perfection, large specific heat capacity, higher surface laser damage threshold and negative photoconductivity.

Study of linear optical parameters of sodium sulphide nano-particles added ADP crystals

NASA Astrophysics Data System (ADS)

Kochuparampil, A. P.; Joshi, J. H.; Dixit, K. P.; Jethva, H. O.; Joshi, M. J.

2017-05-01

Ammonium Dihydrogen Phosphate (ADP) is one of the nonlinear optical crystals. It is having various applications like optical mixing, electro-optical modulator, harmonic generators, etc. Chalcogenide compounds are poorly soluble in water and difficult to add in the water soluble ADP crystals. The solubility of Chalcogenide compounds can be increased by synthesizing the nano-structured samples with suitable capping agent. In the present study sodium sulphide was added in to ADP to modify its linear optical parameters. Sodium sulphide nano particles were synthesized by co-precipitation technique using Ethylene diamine as capping agent followed by microwave irradiation. The powder XRD confirmed the nano-structured nature of sodium sulphide nano particles. The solubility of nanoparticles of sodium sulphide increased significantly in water compared to the bulk. Pure and Na2S added ADP crystals were grown by slow solvent evaporation method at room temperature. The presence of sodium in ADP was confirmed by AAS. The UV-Vis spectra were recorded for all crystals. Various optical parameters like, transmittance, energy band gap, extinction coefficient, refractive index, optical conductivity, etc. were evaluated. The electronic polarizibility of pure and doped crystals calculated from energy band gap. The effect of doping concentration was found on various parameters.

Crystal growth, spectroscopic, DFT computational and third harmonic generation studies of nicotinic acid

NASA Astrophysics Data System (ADS)

Thaya Kumari, C. Rathika; Nageshwari, M.; Raman, R. Ganapathi; Caroline, M. Lydia

2018-07-01

An organic centrosymmetric nicotinic acid (NA) single crystal has been grown employing slow evaporation method in water. NA crystallizes in monoclinic system with centric space group P21/C. The experimental and theoretical investigation includes vibrational spectra based on Hartree - Fock (HF) and density functional theory (DFT) has been applied using different function at B3LYP level of theory using 6-311G++(d,p) basis set. The optical transparency of the title molecule was examined by TD- DFT analysis and for comparison basis experimental UV-Vis spectrum was recorded. The interaction of charge within the molecule was analyzed and the HOMO - LUMO energy gap was evaluated. The value of dipole moment, Mulliken charge and molecular electrostatic potential were estimated at the same level of theory. Also the first order hyper polarizability for NA was calculated. The dielectric behavior of the grown crystal was determined for few selected temperatures. The third order nonlinear response of NA has been examined using Z-scan technique and nonlinear susceptibility (χ3), nonlinear refraction (n2) and nonlinear absorption coefficient (β) has been calculated. The current results clearly indicate that the title compound is an excellent applicant in the domain of opto - electronic applications.

Effect of Co-60 gamma radiation on optical, dielectric and mechanical properties of strontium L-ascorbate hexahydrate NLO crystal

NASA Astrophysics Data System (ADS)

Dileep, M. S.; Suresh Kumar, H. M.

2018-04-01

A potentially useful nonlinear optical semi-organic single crystal of strontium L-ascorbate hexahydrate (SLAH) was grown by solution growth slow evaporation technique at room temperature. The grown crystal is semi transparent, yellowish in color with monoclinic crystal system having space group P21 and is stable up to 198 °C. Further, SLAH crystals were irradiated with gamma rays produced by 60Co with different doses of 10 KGy, 30 KGy and 50 KGy at room temperature and then studied the effect of gamma-rays on dielectric properties, optical absorption, microhardness and SHG efficiency. The absorption study reveals that the absorbance of the grown crystal is appeared to be low throughout the visible region with a lower cutoff wavelength of 277 nm and these parameters are not affected upon gamma irradiation. The luminescence intensity of the crystal is also not affected by the irradiation. There is noticeable changes were observed in dielectric properties and hardness of the materials for different doses of gamma irradiation. The second harmonic generation (SHG) efficiency of the grown crystal is 0.54 times that of the KDP crystal and is decreased moderately by increasing the dosage of gamma irradiation.

Spectroscopic and quantum chemical perspectives on 2-amino 5-methylpyridinium 4-nitrobenzoate - An organic single crystals for optoelectronics device applications

NASA Astrophysics Data System (ADS)

Gandhimathi, A.; Karunakaran, R. T.; Kumaran, A. Elakkina; Prabahar, S.

2018-07-01

In this work, an optical quality single crystals of 2-amino 5-methylpyridinium 4-nitrobenzoate (2A5MPNB) were grown by slow evaporation solution growth technique using methanol as a solvent. The phases and functional groups of 2A5MPNB have been confirmed through powder X-ray diffraction and Fourier transform infrared (FTIR) studies, respectively. The optical transmittance window and the lower cut-off wavelength of the 2A5MPNB have been identified by UV-Vis-NIR studies. Dielectric and photoconductivity studies were also performed for the grown crystals. In order to analyze the mechanical strength Vickers hardness studies were taken for the grown crystal. The thermal behaviour was investigated by TG/DTA studies. NLO and laser damage properties were explored using Nd:YAG laser. Moreover, the quantum chemical calculations on 2A5MPNB have been performed by density functional theory (DFT) calculations using the B3LYP method with 6-311++G(d,p) basis set. The predicted first hyperpolarizability is found to be 14.45 times greater than that of urea and suggests that the title compound could be an attractive material for nonlinear optical applications.

Process development and characterization of centrosymmetric semiorganic nonlinear optical crystal: 4-dimethylaminopyridine potassium chloride

NASA Astrophysics Data System (ADS)

Johnson, J.; Srineevasan, R.; Sivavishnu, D.

2018-06-01

Centrosymmetric semiorganic crystal 4-dimethylaminopyridine potassium chloride (4-DMAPKC) has been grown successfully by using slow evaporation solution growth technique. Powder x-ray diffraction shows the 4-DMAPKC crystal has good crystalline nature. Single crystal XRD shows that the grown 4-DMAPKC is cubic crystal system with cell parameters a = 3.09 Å, b = 3.09 Å, c = 3.09 Å. Investigation has been carried out to assign the Vibrational frequencies of the grown crystal by FTIR spectral studies. UVsbnd Visible NIR optical absorption spectral studies in the range of 200-1100 nm shows low absorption in UVsbnd Visible region with lower cutoff wave length at 261 nm and optical band gap energy was found as Eg = 5.52 eV. Optically transmittance spectral shows 4-DMAPKC crystal is very good transparency in UV-Visible NIR region. Thermogravimetry and differential thermal (TG-DTA) analysis were carried out. Dielectric studies of as grown crystal sample exhibit low dielectric constant and loss at higher frequencies and attests the nonlinear optical activity. Micro hardness studies of as grown crystal were discussed. Second harmonic generation (SHG) efficiency of the 4-DMAPKC is 0.69 times as that of KDP.

Synthesis, characterization and anti-microbial activity of pure, Cu2+ and Cd2+ doped organic NLO l-arginine trifluoroacetate single crystals

NASA Astrophysics Data System (ADS)

Prasanyaa, T.; Haris, M.; Jayaramakrishnan, V.; Amgalan, M.; Mathivanan, V.

2013-10-01

Optically transparent Cu2+ and Cd2+ doped l-arginine trifluoroacetate (LATF) single crystals were grown from its aqueous solution using the slow solvent evaporation technique. The grown crystals were characterized by powder x-ray diffraction to confirm the monoclinic crystal structure. The percentage of transmittance measured using the ultraviolet-visible-near infrared spectrophotometer was found to be more than 80% for doped crystals. The functional group analysis of the grown crystals has been made by Fourier transform infrared spectroscopy. Thermogravimetric/differential thermal analysis was performed for the grown crystals. An atomic absorption study was carried out to determine the presence of Cu2+ and Cd2+. The hardness of the grown crystals was assessed and the results show a significant variation in the hardness value between the pure and doped LATF crystals. The second harmonic generation measurements show that Cu2+ doped LATF is 2.8 times greater and Cd2+ doped is 2.6 times greater than KDP. The anti-bacterial and anti-fungal activities of the title compound were performed using the disc diffusion method against standard bacteria Escherichia coli, Xanthomonas oryzae and against the fungus Aspergillus niger and Aspergillus flavus.

Design-for-Hardware-Trust Techniques, Detection Strategies and Metrics for Hardware Trojans

DTIC Science & Technology

2015-12-14

down  both  rising  and  falling  transitions.  For  Trojan   detection ,   one   fault ,   slow-­‐to-­‐rise  or   slow-­‐to...in Jan. 2016. Through the course of this project we developed novel hardware Trojan detection techniques based on clock sweeping. The technique takes...algorithms to detect minor changes due to Trojan and compared them with those changes made by process variations. This technique was implemented on

The Safe and Efficient Evaporation of a Solvent from Solution

NASA Astrophysics Data System (ADS)

Mahon, Andrew R.

1997-02-01

The process of evaporating a solvent from a solution can cause problems for many students. By using a water-vacuum aspirator, backflashes of water can flood the sample tube and be detrimental to the experiment. This type of apparatus can also cause problems by drawing the solution it is evaporating back into the vacuum hose, causing the student to lose part or all of the products of their experiment. Macroscale and Microscale Organic Experiments, 2nd edition (1), suggested two techniques to dissolve solvents from a mixture. It suggested blowing a stream of air over the solution from a Pasteur pipet, or attaching a Pasteur pipet to an aspirator and drawing air over the surface of the liquid. Again, the danger of blowing air over the solution leaves the risk of splattering the solution, and drawing air over the surface of the liquid as described further endangers the products of the experiment through the risk of sucking the products up into the pipet aspirator. In an effort to eliminate these problems, a new technique has been developed. By inverting an ordinary 200-mL vacuum flask and pulling a steady current of air from the vacuum apparatus through it, any type of small container can be placed under it, allowing the solvent to be evaporated in a steady, mistake-free manner . By evaporating the solvent from the container that the products will be submitted in, no sample is lost through the process of transferring it from a vacuum flask or beaker to the final container.

Salinization owing to evaporation from bare-soil surfaces and its influences on the evaporation

NASA Astrophysics Data System (ADS)

Shimojimaa, Eiichi; Yoshioka, Ryuma; Tamagawa, Ichiro

1996-04-01

To investigate the relationship between evaporation and salinization, the surfaces of three columns of uniform porous materials, desert dune sand, silica sand and glass beads, respectively, were exposed to a temperature-, humidity- and/or wind-speed-controlled ambient atmosphere. For the dune sand, chemicals such as Na +, Ca 2+, Cl - and SO 42-, dissolved mainly from CaSO 4, Na 2SO 4, CaCO 3 and NaC1 in the sand particles, caused marked salinization near the top surface. Slow dissolution of Na 2SO 4 and CaSO 4 influenced the development of concentration profiles for SO 42- and Na + markedly for months after the beginning of the experiment, while the profile of Cl - was not affected directly, because dissolution of NaCl was rapid. Concentration profiles of Cl - for the glass beads and for the silica sand columns filled with a high concentration of NaCI solution of (10 4 mg1 -1 for Cl -), were analysed similarly. Experimental results suggested that the vapour flux in a dry soil became larger because of the increase in the gradient of the vapour density caused by greater chemical enrichment near the top surface compared with that at the evaporation surface. The vapour flux also became smaller as the gradient of the vapour density decreased, owing to the markedly enriched evaporation surface. In the experiment with glass beads, filled with the NaCl solution, solute crystallization (4-10 mm thick) was observed. For the dune sand, only when a turbulent airflow was applied did a crust (a few millimetres in thickness) form entirely on the top surface. Such deposition led to a reduction in the flux of water vapour as the permeable cross-sectional area decreased. The resistance to transfer increased three to ten times for the glass beads but only by 30% for the dune sand. The lower increase for the dune sand may be due to penetration of the applied airflow into cracks in the crust.

On the physical basis of a theory of human thermoregulation.

NASA Technical Reports Server (NTRS)

Iberall, A. S.; Schindler, A. M.

1973-01-01

Theoretical study of the physical factors which are responsible for thermoregulation in nude resting humans in a physical steady state. The behavior of oxidative metabolism, evaporative and convective thermal fluxes, fluid heat transfer, internal and surface temperatures, and evaporative phase transitions is studied by physiological/physical modeling techniques. The modeling is based on the theories that the body has a vital core with autothermoregulation, that the vital core contracts longitudinally, that the temperature of peripheral regions and extremities decreases towards the ambient, and that a significant portion of the evaporative heat may be lost underneath the skin. A theoretical basis is derived for a consistent modeling of steady-state thermoregulation on the basis of these theories.

Microencapsulation Processes

NASA Astrophysics Data System (ADS)

Whateley, T. L.; Poncelet, D.

2005-06-01

Microencapsulation by solvent evaporation is a novel technique to enable the controlled delivery of active materials.The controlled release of drugs, for example, is a key challenge in the pharmaceutical industries. Although proposed several decades ago, it remains largely an empirical laboratory process.The Topical Team has considered its critical points and the work required to produce a more effective technology - better control of the process for industrial production, understanding of the interfacial dynamics, determination of the solvent evaporation profile, and establishment of the relation between polymer/microcapsule structures.The Team has also defined how microgravity experiments could help in better understanding microencapsulation by solvent evaporation, and it has proposed a strategy for a collaborative project on the topic.

A RECONNECTION-DRIVEN MODEL OF THE HARD X-RAY LOOP-TOP SOURCE FROM FLARE 2004 FEBRUARY 26

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

Longcope, Dana; Qiu, Jiong; Brewer, Jasmine

A compact X-class flare on 2004 February 26 showed a concentrated source of hard X-rays at the tops of the flare’s loops. This was analyzed in previous work and interpreted as plasma heated and compressed by slow magnetosonic shocks (SMSs) generated during post-reconnection retraction of the flux. That work used analytic expressions from a thin flux tube (TFT) model, which neglected many potentially important factors such as thermal conduction and chromospheric evaporation. Here we use a numerical solution of the TFT equations to produce a more comprehensive and accurate model of the same flare, including those effects previously omitted. Thesemore » simulations corroborate the prior hypothesis that slow-mode shocks persist well after the retraction has ended, thus producing a compact, loop-top source instead of an elongated jet, as steady reconnection models predict. Thermal conduction leads to densities higher than analytic estimates had predicted, and evaporation enhances the density still higher, but at lower temperatures. X-ray light curves and spectra are synthesized by convolving the results from a single TFT simulation with the rate at which flux is reconnected, as measured through motion of flare ribbons, for example. These agree well with light curves observed by RHESSI and GOES and spectra from RHESSI . An image created from a superposition of TFT model runs resembles one produced from RHESSI observations. This suggests that the HXR loop-top source, at least the one observed in this flare, could be the result of SMSs produced in fast reconnection models like Petschek’s.« less

Artificial Intelligence Techniques for Predicting and Mapping Daily Pan Evaporation

NASA Astrophysics Data System (ADS)

Arunkumar, R.; Jothiprakash, V.; Sharma, Kirty

2017-09-01

In this study, Artificial Intelligence techniques such as Artificial Neural Network (ANN), Model Tree (MT) and Genetic Programming (GP) are used to develop daily pan evaporation time-series (TS) prediction and cause-effect (CE) mapping models. Ten years of observed daily meteorological data such as maximum temperature, minimum temperature, relative humidity, sunshine hours, dew point temperature and pan evaporation are used for developing the models. For each technique, several models are developed by changing the number of inputs and other model parameters. The performance of each model is evaluated using standard statistical measures such as Mean Square Error, Mean Absolute Error, Normalized Mean Square Error and correlation coefficient (R). The results showed that daily TS-GP (4) model predicted better with a correlation coefficient of 0.959 than other TS models. Among various CE models, CE-ANN (6-10-1) resulted better than MT and GP models with a correlation coefficient of 0.881. Because of the complex non-linear inter-relationship among various meteorological variables, CE mapping models could not achieve the performance of TS models. From this study, it was found that GP performs better for recognizing single pattern (time series modelling), whereas ANN is better for modelling multiple patterns (cause-effect modelling) in the data.

Use of simulated evaporation to assess the potential for scale formation during reverse osmosis desalination

USGS Publications Warehouse

Huff, G.F.

2004-01-01

The tendency of solutes in input water to precipitate efficiency lowering scale deposits on the membranes of reverse osmosis (RO) desalination systems is an important factor in determining the suitability of input water for desalination. Simulated input water evaporation can be used as a technique to quantitatively assess the potential for scale formation in RO desalination systems. The technique was demonstrated by simulating the increase in solute concentrations required to form calcite, gypsum, and amorphous silica scales at 25??C and 40??C from 23 desalination input waters taken from the literature. Simulation results could be used to quantitatively assess the potential of a given input water to form scale or to compare the potential of a number of input waters to form scale during RO desalination. Simulated evaporation of input waters cannot accurately predict the conditions under which scale will form owing to the effects of potentially stable supersaturated solutions, solution velocity, and residence time inside RO systems. However, the simulated scale-forming potential of proposed input waters could be compared with the simulated scale-forming potentials and actual scale-forming properties of input waters having documented operational histories in RO systems. This may provide a technique to estimate the actual performance and suitability of proposed input waters during RO.

Reaching the Connected Generation: "College Access Marketers" Slow in Adopting New Techniques

ERIC Educational Resources Information Center

Gastwirth, David

2007-01-01

This author states that "college access marketing" efforts aimed at increasing college attendance and success have been slow to incorporate new techniques such as "buzz marketing," "viral marketing," "product seeding," and "guerrilla marketing." Yet for a "connected generation" of potential college students, these kinds of strategies could be…

The relationship between two fast/slow analysis techniques for bursting oscillations

PubMed Central

Teka, Wondimu; Tabak, Joël; Bertram, Richard

2012-01-01

Bursting oscillations in excitable systems reflect multi-timescale dynamics. These oscillations have often been studied in mathematical models by splitting the equations into fast and slow subsystems. Typically, one treats the slow variables as parameters of the fast subsystem and studies the bifurcation structure of this subsystem. This has key features such as a z-curve (stationary branch) and a Hopf bifurcation that gives rise to a branch of periodic spiking solutions. In models of bursting in pituitary cells, we have recently used a different approach that focuses on the dynamics of the slow subsystem. Characteristic features of this approach are folded node singularities and a critical manifold. In this article, we investigate the relationships between the key structures of the two analysis techniques. We find that the z-curve and Hopf bifurcation of the two-fast/one-slow decomposition are closely related to the voltage nullcline and folded node singularity of the one-fast/two-slow decomposition, respectively. They become identical in the double singular limit in which voltage is infinitely fast and calcium is infinitely slow. PMID:23278052

Alloy vapor deposition using ion plating and flash evaporation

NASA Technical Reports Server (NTRS)

Spalvins, T.

1971-01-01

Method extends scope of ion plating technique to include deposition of alloy films without changing composition of plating alloy. Coatings flow with specimen material without chipping or peeling. Technique is most effective vacuum deposition method for depositing alloys for strong and lasting adherence.

Atmospheric pressure matrix-assisted laser desorption ionization as a plume diagnostic tool in laser evaporation methods

NASA Astrophysics Data System (ADS)

Callahan, John H.; Galicia, Marsha C.; Vertes, Akos

2002-09-01

Laser evaporation techniques, including matrix-assisted pulsed laser evaporation (MAPLE), are attracting increasing attention due to their ability to deposit thin layers of undegraded synthetic and biopolymers. Laser evaporation methods can be implemented in reflection geometry with the laser and the substrate positioned on the same side of the target. In some applications (e.g. direct write, DW), however, transmission geometry is used, i.e. the thin target is placed between the laser and the substrate. In this case, the laser pulse perforates the target and transfers some target material to the substrate. In order to optimize evaporation processes it is important to know the composition of the target plume and the material deposited from the plume. We used a recently introduced analytical method, atmospheric pressure matrix-assisted laser desorption ionization (AP-MALDI) to characterize the ionic components of the plume both in reflection and in transmission geometry. This technique can also be used to directly probe materials deposited on surfaces (such as glass slides) by laser evaporation methods. The test compound (small peptides, e.g. Angiotensin I, ATI or Substance P) was mixed with a MALDI matrix (α-cyano-4-hydroxycinnamic acid (CHCA), sinapinic acid (SA) or 2,5-dihydroxybenzoic acid (DHB)) and applied to the stainless steel (reflection geometry) or transparent conducting (transmission geometry) target holder. In addition to the classical dried droplet method, we also used electrospray target deposition to gain better control of crystallite size, thickness and homogeneity. The target was mounted in front of the inlet orifice of an ion trap mass spectrometer (IT-MS) that sampled the ionic components of the plume generated by a nitrogen laser. We studied the effect of several parameters, such as, the orifice to target distance, illumination geometry, extracting voltage distribution and sample preparation on the generated ions. Various analyte-matrix and matrix-matrix cluster ions were observed with relatively low abundance of the matrix ions.

A closed unventilated chamber for the measurement of transepidermal water loss.

PubMed

Nuutinen, Jouni; Alanen, Esko; Autio, Pekka; Lahtinen, Marjo-Riitta; Harvima, Ilkka; Lahtinen, Tapani

2003-05-01

Open chamber systems for measuring transepidermal water loss (TEWL) have limitations related to ambient and body-induced airflows near the probe, probe size, measurement sites and angles, and measurement range. The aim of the present investigation was to develop a closed chamber system for the TEWL measurement without significant blocking of normal evaporation through the skin. Additionally, in order to use the evaporimeter to measure evaporation rates through other biological and non-biological specimens and in the field applications, a small portable, battery-operated device was a design criteria. A closed unventilated chamber (inner volume 2.0 cm(3) was constructed. For the skin measurement, the chamber with one side open (open surface area 1.0 cm(2) is placed on the skin. The skin application time was investigated at low and high evaporation rates in order to assess the blocking effect of the chamber on normal evaporation. From the rising linear part of the relative humidity (RH) in the chamber the slope was registered. The slope was calibrated into a TEWL value by evaporating water at different temperatures and measuring the water loss of heated samples with a laboratory scale. The closed chamber evaporation technique was compared with a conventional evaporimeter based on an open chamber method (DermaLab), Cortex Technology, Hadsund, Denmark). The reproducibility of the closed chamber method was measured with the water samples and with volar forearm and palm of the hand in 10 healthy volunteers. The skin application time varied between 7 and 9 s and the linear slope region between 3 and 5 s at the evaporation rates of 3-220 g/m(2) h. A correlation coefficient between the TEWL value from the closed chamber measurements and the readings of the laboratory scale was 0.99 (P < 0.001). The reproducibility of the evaporation measurements with the water samples was 4.0% at the evaporation rate of 40 g/m(2) h. A correlation coefficient of the TEWL values between the closed chamber and open chamber measurements was 0.99 (P < 0.001) in the range where the response of a conventional evaporimeter was linear (until 120 g/m(2)h. With volar forearm and palm of the hand of 10 healthy volunteers the reproducibility of the measurements was 8.0 and 10.1%. The closed chamber technique solves the drawbacks related to open chamber evaporimeters. Especially, it extends the measurement range to high evaporation rates and TEWL measurements can be performed practically at any anatomical sites and measurement angle. By the use of a closed chamber the disturbance related to external or body-induced air flows on the measurement can be avoided.

Effects of must concentration techniques on wine isotopic parameters.

PubMed

Guyon, Francois; Douet, Christine; Colas, Sebastien; Salagoïty, Marie-Hélène; Medina, Bernard

2006-12-27

Despite the robustness of isotopic methods applied in the field of wine control, isotopic values can be slightly influenced by enological practices. For this reason, must concentration technique effects on wine isotopic parameters were studied. The two studied concentration techniques were reverse osmosis (RO) and high-vacuum evaporation (HVE). Samples (must and extracted water) have been collected in various French vineyards. Musts were microfermented at the laboratory, and isotope parameters were determined on the obtained wine. Deuterium and carbon-13 isotope ratios were studied on distilled ethanol by nuclear magnetic resonance (NMR) and isotope ratio mass spectrometry (IRMS), respectively. The oxygen-18 ratio was determined on extracted and wine water using IRMS apparatus. The study showed that the RO technique has a very low effect on isotopic parameters, indicating that this concentration technique does not create any isotopic fractionation, neither at sugar level nor at water level. The effect is notable for must submitted to HVE concentration: water evaporation leads to a modification of the oxygen-18 ratio of the must and, as a consequence, ethanol deuterium concentration is also modified.

Combination of acoustic levitation with small angle scattering techniques and synchrotron radiation circular dichroism. Application to the study of protein solutions.

PubMed

Cristiglio, Viviana; Grillo, Isabelle; Fomina, Margarita; Wien, Frank; Shalaev, Evgenyi; Novikov, Alexey; Brassamin, Séverine; Réfrégiers, Matthieu; Pérez, Javier; Hennet, Louis

2017-01-01

The acoustic levitation technique is a useful sample handling method for small solid and liquids samples, suspended in air by means of an ultrasonic field. This method was previously used at synchrotron sources for studying pharmaceutical liquids and protein solutions using x-ray diffraction and small angle x-ray scattering (SAXS). In this work we combined for the first time this containerless method with small angle neutron scattering (SANS) and synchrotron radiation circular dichroism (SRCD) to study the structural behavior of proteins in solutions during the water evaporation. SANS results are also compared with SAXS experiments. The aggregation behavior of 45μl droplets of lysozyme protein diluted in water was followed during the continuous increase of the sample concentration by evaporating the solvent. The evaporation kinetics was followed at different drying stage by SANS and SAXS with a good data quality. In a prospective work using SRCD, we also studied the evolution of the secondary structure of the myoglobin protein in water solution in the same evaporation conditions. Acoustic levitation was applied for the first time with SANS and the high performances of the used neutron instruments made it possible to monitor fast container-less reactions in situ. A preliminary work using SRCD shows the potentiality of its combination with acoustic levitation for studying the evolution of the protein structure with time. This multi-techniques approach could give novel insights into crystallization and self-assembly phenomena of biological compound with promising potential applications in pharmaceutical, food and cosmetics industry. This article is part of a Special Issue entitled "Science for Life" Guest Editor: Dr. Austen Angell, Dr. Salvatore Magazù and Dr. Federica Migliardo. Copyright © 2016 Elsevier B.V. All rights reserved.

Experimental and computational studies on creatininium 4-nitrobenzoate - An organic proton transfer complex

NASA Astrophysics Data System (ADS)

Thirumurugan, R.; Anitha, K.

2017-10-01

A new organic proton transfer complex of creatininium 4-nitrobenzoate (C4NB) has been synthesized and its single crystals were grown successfully by slow evaporation technique. The grown single crystal was subjected to various characterization techniques like single crystal X-ray diffraction (SCXRD), FTIR, FT-Raman and Kurtz-Perry powder second harmonic generation (SHG). The SCXRD analysis revealed that C4NB was crystallized into orthorhombic crystal system, with noncentrosymmetric (NCS), P212121 space group. The creatininium cation and 4-nitrobenzoate anion were connected through a pair of N__H⋯O hydrogen bonds (N(3)__H(6) ⋯ O(3) (x+1, y, z) and N(2)__H(5) &ctdot O(2) (x-1/2, -y-1/2, -z+2)) and fashioned a R22(8) ring motif. The crystal structure was stabilized by strong N__H⋯O and weak C__H⋯O intermolecular interactions and it was quantitatively analysed by Hirshfeld surface and fingerprint (FP) analysis. FTIR and FT-Raman studies confirmed the vibrational modes of functional groups present in C4NB compound indubitably. SHG efficiency of grown crystal was 4.6 times greater than that of standard potassium dihydrogen phosphate (KDP) material. Moreover, density functional theory (DFT) studies such as Mulliken charge distribution, frontier molecular orbitals (FMOs), molecular electrostatic potential (MEP) map, natural bond orbital analysis (NBO) and first order hyperpolarizability (β0) were calculated to explore the structure-property relationship.

Spectral, optical, thermal, Hirshfeld, antimicrobial studies and computational calculations of a new organic crystal, 1H-benzo[d]imidazol-3-ium-3,5-dinitrobenzoate

NASA Astrophysics Data System (ADS)

Sathya, K.; Dhamodharan, P.; Dhandapani, M.

2017-06-01

Single crystals of 1H-benzo[d]imidazol-3-ium-3,5-dinitrobenzoate (BDNB) were grown by reacting 3,5-dinitrobenzoic acid and benzimidazole by slow evaporation method. UV-Vis-NIR spectral studies of the BDNB show that the crystal is excellently transparent in entire visible region. Chemically and magnetically equivalent protons in BDNB were identified by 1H NMR technique. The carbon frame work of the molecule was established by 13C NMR spectroscopy. Proton transfer mechanism was confirmed by the presence of N+H group in BDNB by FT-IR spectroscopic technique. TG/DTA analyses confirmed that the crystal is stable up to172 °C. Single crystal XRD analysis was carried out to ascertain the molecular structure and the crystal belongs to monoclinic system with space group P21/c. Computational studies that include optimization of molecular geometry, natural bond analysis, Mulliken population analysis and HOMO-LUMO analysis were performed using B3LYP method at 6-31 g level. The low HOMO-LUMO energy gap of BDNB confirms high reactivity of BDNB. Hirshfeld analysis expose that O⋯H/H⋯O interactions are the prominent interactions. Theoretical calculations indicate that first order hyperpolarizability is 16 times greater than urea. The results show that the BDNB may be used for opto-electronic applications. The antimicrobial and antioxidant analyses shows concentration of the compound increases inhibition activity also increases.

Inter-particle interaction dependent evaporation-induced assembly in contact-free micro-colloidal droplets

NASA Astrophysics Data System (ADS)

Sen, Debasis; Biswas, Priyanka; Melo, J. S.

2018-04-01

Evaporation-induced assembly of constituent particles in tiny dispersion droplet allows an efficient way to realize nano-structured micro-granules with potential for various applications. Morphology of the granules, obtained by such one-step dispersion to granular transformation, is decided by several physicochemical conditions. Here we demonstrate that the inter-particle interaction plays a crucial role in deciding the assembled morphology. Resultant granules are investigated by complementary techniques, Electron microscopy and small-angle scattering.

Effects of solvent evaporation conditions on solvent vapor annealed cylinder-forming block polymer thin films

NASA Astrophysics Data System (ADS)

Grant, Meagan; Jakubowski, William; Nelson, Gunnar; Drapes, Chloe; Baruth, A.

Solvent vapor annealing is a less time and energy intensive method compared to thermal annealing, to direct the self-assembly of block polymer thin films. Periodic nanostructures have applications in ultrafiltration, magnetic arrays, or other structures with nanometer dimensions, driving its continued interest. Our goal is to create thin films with hexagonally packed, perpendicular aligned cylinders of poly(lactide) in a poly(styrene) matrix that span the thickness of the film with low anneal times and low defect densities, all with high reproducibility, where the latter is paramount. Through the use of our computer-controlled, pneumatically-actuated, purpose-built solvent vapor annealing chamber, we have the ability to monitor and control vapor pressure, solvent concentration within the film, and solvent evaporation rate with unprecedented precision and reliability. Focusing on evaporation, we report on two previously unexplored areas, chamber pressure during solvent evaporation and the flow rate of purging gas aiding the evaporation. We will report our exhaustive results following atomic force microscopy analysis of films exposed to a wide range of pressures and flow rates. Reliably achieving well-ordered films, while occurring within a large section of this parameter space, was correlated with high-flow evaporation rates and low chamber pressures. These results have significant implications on other methods of solvent annealing, including ``jar'' techniques.

Theoretical and Experimental Investigation of the Stability of an Evaporating Constrained Vapor Bubble

NASA Technical Reports Server (NTRS)

Wayner, P. C., Jr.; Plawsky, J. L.; Wong, Harris

2004-01-01

The major accomplishments of the experimental portion of the research were documented in Ling Zheng's doctoral dissertation. Using Pentane, he obtained a considerable amount of data on the stability and heat transfer characteristics of an evaporating meniscus. The important points are that experimental equipment to obtain data on the stability and heat transfer characteristics of an evaporating meniscus were built and successfully operated. The data and subsequent analyses were accepted by the Journal of Heat Transfer for publication in 2004 [PU4]. The work was continued by a new graduate student using HFE-7000 [PU3] and then Pentane at lower heat fluxes. The Pentane results are being analyzed for publication. The experimental techniques are currently being used in our other NASA Grant. The oscillation of the contact line observed in the experiments involves evaporation (retraction part) and spreading. Since both processes occur with finite contact angles, it is important to derive a precise equation of the intermolecular forces (disjoining pressure) valid for non-zero contact angles. This theoretical derivation was accepted for publication by Journal of Fluid Mechanics [PU5]. The evaporation process near the contact line is complicated, and an idealized micro heat pipe has been proposed to help in elucidating the detailed evaporation process [manuscripts in preparation].

Comparison of Total Evaporation (TE) and Direct Total Evaporation (DTE) methods in TIMS by using NBL CRMs

NASA Astrophysics Data System (ADS)

Hasözbek, Altug; Mathew, Kattathu; Wegener, Michael

2013-04-01

The total evaporation (TE) is a well-established analytical method for safeguards measurement of uranium and plutonium isotope-amount ratios using the thermal ionization mass spectrometry (TIMS). High accuracy and precision isotopic measurements find many applications in nuclear safeguards, for e.g. assay measurements using isotope dilution mass spectrometry. To achieve high accuracy and precision in TIMS measurements, mass dependent fractionation effects are minimized by either the measurement technique or changes in the hardware components that are used to control sample heating and evaporation process. At NBL, direct total evaporation (DTE) method on the modified MAT261 instrument, uses the data system to read the ion signal intensity and its difference from a pre-determined target intensity, is used to control the incremental step at which the evaporation filament is heated. The feedback and control is achieved by proprietary hardware from SPECTROMAT that uses an analog regulator in the filament power supply with direct feedback of the detector intensity. Compared to traditional TE method on this instrument, DTE provides better precision (relative standard deviation, expressed as a percent) and accuracy (relative difference, expressed as a percent) of 0.05 to 0.08 % for low enriched and high enriched NBL uranium certified reference materials.

Novel one-pot facile technique for preparing nanoparticles modified with hydrophilic polymers on the surface via block polymer-assisted emulsification/evaporation process.

PubMed

Kanakubo, Yurie; Ito, Fuminori; Murakami, Yoshihiko

2010-06-15

In this paper, we describe the novel facile technique for preparing surface-modified nanoparticles via newly developed amphiphilic block polymer-assisted emulsification/evaporation process. The effects of both organic solvents (the dispersed phase) and stabilizer in the external continuous phase on the stability of o/w emulsion was firstly investigated to clarify the optimal conditions for stable emulsification/evaporation processes. We found that the organic solvent mixture having a density adjusted to be 1.00 g/cm(3) gave the highly stable o/w emulsion. Under the optimal conditions, the relatively monodisperse poly(ethylene glycol) (PEG)-modified poly(lactide-co-glycolide) (PLGA) nanoparticle was obtained and characterized. The introduction of PEG to the particle surface was suggested by the fact that the diameter and zeta potential of the particle increased as the amount of added block polymer increased. The facile method presented in this paper can be a universal tool for modifying the surface of nanoparticles, even though reactive groups are not present on the surface. Copyright 2010 Elsevier B.V. All rights reserved.

Mid-infrared laser-absorption diagnostic for vapor-phase measurements in an evaporating n-decane aerosol

NASA Astrophysics Data System (ADS)

Porter, J. M.; Jeffries, J. B.; Hanson, R. K.

2009-09-01

A novel three-wavelength mid-infrared laser-based absorption/extinction diagnostic has been developed for simultaneous measurement of temperature and vapor-phase mole fraction in an evaporating hydrocarbon fuel aerosol (vapor and liquid droplets). The measurement technique was demonstrated for an n-decane aerosol with D 50˜3 μ m in steady and shock-heated flows with a measurement bandwidth of 125 kHz. Laser wavelengths were selected from FTIR measurements of the C-H stretching band of vapor and liquid n-decane near 3.4 μm (3000 cm -1), and from modeled light scattering from droplets. Measurements were made for vapor mole fractions below 2.3 percent with errors less than 10 percent, and simultaneous temperature measurements over the range 300 K< T<900 K were made with errors less than 3 percent. The measurement technique is designed to provide accurate values of temperature and vapor mole fraction in evaporating polydispersed aerosols with small mean diameters ( D 50<10 μ m), where near-infrared laser-based scattering corrections are prone to error.

Smoothed particle hydrodynamics method for evaporating multiphase flows.

PubMed

Yang, Xiufeng; Kong, Song-Charng

2017-09-01

The smoothed particle hydrodynamics (SPH) method has been increasingly used for simulating fluid flows; however, its ability to simulate evaporating flow requires significant improvements. This paper proposes an SPH method for evaporating multiphase flows. The present SPH method can simulate the heat and mass transfers across the liquid-gas interfaces. The conservation equations of mass, momentum, and energy were reformulated based on SPH, then were used to govern the fluid flow and heat transfer in both the liquid and gas phases. The continuity equation of the vapor species was employed to simulate the vapor mass fraction in the gas phase. The vapor mass fraction at the interface was predicted by the Clausius-Clapeyron correlation. An evaporation rate was derived to predict the mass transfer from the liquid phase to the gas phase at the interface. Because of the mass transfer across the liquid-gas interface, the mass of an SPH particle was allowed to change. Alternative particle splitting and merging techniques were developed to avoid large mass difference between SPH particles of the same phase. The proposed method was tested by simulating three problems, including the Stefan problem, evaporation of a static drop, and evaporation of a drop impacting a hot surface. For the Stefan problem, the SPH results of the evaporation rate at the interface agreed well with the analytical solution. For drop evaporation, the SPH result was compared with the result predicted by a level-set method from the literature. In the case of drop impact on a hot surface, the evolution of the shape of the drop, temperature, and vapor mass fraction were predicted.

Evaluating the hydrological consistency of evaporation products using satellite-based gravity and rainfall data

NASA Astrophysics Data System (ADS)

López, Oliver; Houborg, Rasmus; McCabe, Matthew Francis

2017-01-01

Advances in space-based observations have provided the capacity to develop regional- to global-scale estimates of evaporation, offering insights into this key component of the hydrological cycle. However, the evaluation of large-scale evaporation retrievals is not a straightforward task. While a number of studies have intercompared a range of these evaporation products by examining the variance amongst them, or by comparison of pixel-scale retrievals against ground-based observations, there is a need to explore more appropriate techniques to comprehensively evaluate remote-sensing-based estimates. One possible approach is to establish the level of product agreement between related hydrological components: for instance, how well do evaporation patterns and response match with precipitation or water storage changes? To assess the suitability of this consistency-based approach for evaluating evaporation products, we focused our investigation on four globally distributed basins in arid and semi-arid environments, comprising the Colorado River basin, Niger River basin, Aral Sea basin, and Lake Eyre basin. In an effort to assess retrieval quality, three satellite-based global evaporation products based on different methodologies and input data, including CSIRO-PML, the MODIS Global Evapotranspiration product (MOD16), and Global Land Evaporation: the Amsterdam Methodology (GLEAM), were evaluated against rainfall data from the Global Precipitation Climatology Project (GPCP) along with Gravity Recovery and Climate Experiment (GRACE) water storage anomalies. To ensure a fair comparison, we evaluated consistency using a degree correlation approach after transforming both evaporation and precipitation data into spherical harmonics. Overall we found no persistent hydrological consistency in these dryland environments. Indeed, the degree correlation showed oscillating values between periods of low and high water storage changes, with a phase difference of about 2-3 months. Interestingly, after imposing a simple lag in GRACE data to account for delayed surface runoff or baseflow components, an improved match in terms of degree correlation was observed in the Niger River basin. Significant improvements to the degree correlations (from ˜ 0 to about 0.6) were also found in the Colorado River basin for both the CSIRO-PML and GLEAM products, while MOD16 showed only half of that improvement. In other basins, the variability in the temporal pattern of degree correlations remained considerable and hindered any clear differentiation between the evaporation products. Even so, it was found that a constant lag of 2 months provided a better fit compared to other alternatives, including a zero lag. From a product assessment perspective, no significant or persistent advantage could be discerned across any of the three evaporation products in terms of a sustained hydrological consistency with precipitation and water storage anomaly data. As a result, our analysis has implications in terms of the confidence that can be placed in independent retrievals of the hydrological cycle, raises questions on inter-product quality, and highlights the need for additional techniques to evaluate large-scale products.

Crystal growth, structure analysis and characterisation of 2 - (1, 3 - dioxoisoindolin - 2 - yl) acetic acid single crystal

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

Sankari, R. Siva, E-mail: sivasankari.sh@act.edu.in; Perumal, Rajesh Narayana

2014-04-24

Single crystal of dielectric material 2 - (1, 3 - dioxoisoindolin - 2 - yl) acetic acid has been grown by slow evaporation solution growth method. The grown crystal was harvested in 25 days. The crystal structure was analyzed by Single crystal X - ray diffraction. UV-vis-NIR analysis was performed to examine the optical property of the grown crystal. The thermal property of the grown crystal was studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The dielectric measurements were carried out and the dielectric constant was calculated and plotted at all frequencies.

Three-dimensional wax patterning of paper fluidic devices.

PubMed

Renault, Christophe; Koehne, Jessica; Ricco, Antonio J; Crooks, Richard M

2014-06-17

In this paper we describe a method for three-dimensional wax patterning of microfluidic paper-based analytical devices (μPADs). The method is rooted in the fundamental details of wax transport in paper and provides a simple way to fabricate complex channel architectures such as hemichannels and fully enclosed channels. We show that three-dimensional μPADs can be fabricated with half as much paper by using hemichannels rather than ordinary open channels. We also provide evidence that fully enclosed channels are efficiently isolated from the exterior environment, decreasing contamination risks, simplifying the handling of the device, and slowing evaporation of solvents.

Long length coated conductor fabrication by inclined substrate deposition and evaporation

NASA Astrophysics Data System (ADS)

Prusseit, W.; Hoffmann, C.; Nemetschek, R.; Sigl, G.; Handke, J.; Lümkemann, A.; Kinder, H.

2006-06-01

The commercial development of coated conductors is rapidly progressing. As a result we present an economic route to produce second generation HTS tape from the initial substrate preparation to the final metal coating. The most important and technically challenging steps are the deposition of an oriented buffer layer and the superconductor film in a reel-to-reel configuration. New evaporation techniques have been developed to enable reliable, high rate tape coating. Highly oriented MgO - buffer layers are realized by inclined substrate deposition (ISD) and DyBCO is deposited by simple e-gun evaporation yielding critical currents beyond 200 A/cm. Coated conductors have been fabricated up to 40 m length and are currently tested in a variety of applications.

Synthesis and characterisation of co-evaporated tin sulphide thin films

NASA Astrophysics Data System (ADS)

Koteeswara Reddy, N.; Ramesh, K.; Ganesan, R.; Ramakrishna Reddy, K. T.; Gunasekhar, K. R.; Gopal, E. S. R.

2006-04-01

Tin sulphide films were grown at different substrate temperatures by a thermal co-evaporation technique. The crystallinity of the films was evaluated from X-ray diffraction studies. Single-phase SnS films showed a strong (040) orientation with an orthorhombic crystal structure and a grain size of 0.12 μm. The films showed an electrical resistivity of 6.1 Ω cm with an activation energy of 0.26 eV. These films exhibited an optical band gap of 1.37 eV and had a high optical absorption coefficient (>104 cm-1) above the band-gap energy. The results obtained were analysed to evaluate the potentiality of the co-evaporated SnS films as an absorber layer in solar photovoltaic devices.

First demonstration of the fast-to-slow corrector current shift in the NSLS-II storage ring

NASA Astrophysics Data System (ADS)

Yang, Xi; Tian, Yuke; Yu, Li Hua; Smaluk, Victor

2018-04-01

To realize the full benefits of the high brightness and ultra-small beam sizes of NSLS-II, it is essential that the photon beams are exceedingly stable. In the circumstances of implementing local bumps, changing ID gaps, and long term drifting, the fast orbit feedback (FOFB) requires shifting the fast corrector strengths to the slow correctors to prevent the fast corrector saturation and to make the beam orbit stable in the sub-micron level. As the result, a reliable and precise technique of fast-to-slow corrector strength shift has been developed and tested at NSLS-II. This technique is based on the fast corrector response to the slow corrector change when the FOFB is on. In this article, the shift technique is described and the result of proof-of-principle experiment carried out at NSLS-II is presented. The maximum fast corrector current was reduced from greater than 0.45 A to less than 0.04 A with the orbit perturbation within ±1 μm.

Evaporation and abstraction determined from stable isotopes during normal flow on the Gariep River, South Africa

NASA Astrophysics Data System (ADS)

Diamond, Roger E.; Jack, Sam

2018-04-01

Changes in the stable isotope composition of water can, with the aid of climatic parameters, be used to calculate the quantity of evaporation from a water body. Previous workers have mostly focused on small, research catchments, with abundant data, but of limited scope. This study aimed to expand such work to a regional or sub-continental scale. The first full length isotope survey of the Gariep River quantifies evaporation on the river and the man-made reservoirs for the first time, and proposes a technique to calculate abstraction from the river. The theoretically determined final isotope composition for an evaporating water body in the given climate lies on the empirically determined local evaporation line, validating the assumptions and inputs to the Craig-Gordon evaporation model that was used. Evaporation from the Gariep River amounts to around 20% of flow, or 40 m3/s, of which about half is due to evaporation from the surface of the Gariep and Vanderkloof Reservoirs, showing the wastefulness of large surface water impoundments. This compares well with previous estimates based on evapotranspiration calculations, and equates to around 1300 GL/a of water, or about the annual water consumption of Johannesburg and Pretoria, where over 10 million people reside. Using similar evaporation calculations and applying existing transpiration estimates to a gauged length of river, the remaining quantity can be attributed to abstraction, amounting to 175 L/s/km in the lower middle reaches of the river. Given that high water demand and climate change are global problems, and with the challenges of maintaining water monitoring networks, stable isotopes are shown to be applicable over regional to national scales for modelling hydrological flows. Stable isotopes provide a complementary method to conventional flow gauging for understanding hydrology and management of large water resources, particularly in arid areas subject to significant evaporation.

Influence of tartaric acid on linear-nonlinear optical and electrical properties of KH2PO4 crystal

NASA Astrophysics Data System (ADS)

Baig, M. I.; Anis, Mohd; Muley, G. G.

2017-10-01

KH2PO4 (KDOP) is widely demanded technological crystal for applications in laser driven photonic devices. Therefore, present article is focused to investigate the effect of tartaric acid (TA) on laser induced nonlinear optical properties of KDOP crystal. The optically transparent TA doped KDOP crystal of size 15 × 10 × 04 mm3 has been grown by slow solvent evaporation technique at 35 °C. The structural analysis of pure and TA doped KDOP crystal has been achieved by means of single crystal X-ray diffraction technique. The functional groups of TA doped KDOP crystal has been identified by means of Fourier transform infrared spectral analysis. The UV-visible studies have been performed to determine the optical transparency and evaluate the linear optical constants of pure and TA doped KDOP crystal. The Kurtz-Perry test has been employed to confirm the frequency doubling phenomenon of crystal and the SHG efficiency of TA doped KDOP crystal is found to be 5.68 times higher than that of standard KDP material. The Z-scan technique has been employed to explore the third order nonlinear optical (TONLO) refraction (n2), absorption (β) and susceptibility (χ3) of pure and TA doped KDOP crystal at 632.8 nm. The TA facilitated optical switching in TONLO response of KDOP crystal is found to be an interesting effect to examine. The laser damage threshold of TA doped KDOP crystal has been determined at 1064 nm using the Nd:YAG laser. The comparative electrical analysis on pure and TA doped KDOP crystal has been accomplished by means of dielectric and photoconductivity characterization studies.

Investigation on the growth, spectral, lifetime, mechanical analysis and third-order nonlinear optical studies of L-methionine admixtured D-mandelic acid single crystal: A promising material for nonlinear optical applications

NASA Astrophysics Data System (ADS)

Jayaprakash, P.; Sangeetha, P.; Kumari, C. Rathika Thaya; Caroline, M. Lydia

2017-08-01

A nonlinear optical bulk single crystal of L-methionine admixtured D-mandelic acid (LMDMA) has been grown by slow solvent evaporation technique using water as solvent at ambient temperature. The crystallized LMDMA single crystal subjected to single crystal X-ray diffraction study confirmed monoclinic system with the acentric space group P21. The FTIR analysis gives information about the modes of vibration in the various functional groups present in LMDMA. The UV-visible spectral analysis assessed the optical quality and linear optical properties such as extinction coefficient, reflectance, refractive index and from which optical conductivity and electric susceptibility were also evaluated. The frequency doubling efficiency was observed using Kurtz Perry powder technique. A multiple shot laser was utilized to evaluate the laser damage threshold energy of the crystal. Discrete thermodynamic properties were carried out by TG-DTA studies. The hardness, Meyer's index, yield strength, elastic stiffness constant, Knoop hardness, fracture toughness and brittleness index were analyzed using Vickers microhardness tester. Layer growth pattern and the surface defect were examined by chemical etching studies using optical microscope. Fluorescence emission spectrum was recorded and lifetime was also studied. The electric field response of crystal was investigated from the dielectric studies at various temperatures at different frequencies. The third-order nonlinear optical response in LMDMA has been investigated using Z-scan technique with He-Ne laser at 632.8 nm and nonlinear parameters such as refractive index (n2), absorption coefficient (β) and susceptibility (χ3) investigated extensively for they are in optical phase conjucation, high-speed optical switches and optical dielectric devices.

Nonlinear optical and microscopic analysis of Cu2+ doped zinc thiourea chloride (ZTC) monocrystal

NASA Astrophysics Data System (ADS)

Ramteke, S. P.; Anis, Mohd; Pandian, M. S.; Kalainathan, S.; Baig, M. I.; Ramasamy, P.; Muley, G. G.

2018-02-01

Organometallic crystals offer considerable nonlinear response therefore, present article focuses on bulk growth and investigation of Cu2+ ion doped zinc thiourea chloride (ZTC) crystal to explore its technological impetus for laser assisted nonlinear optical (NLO) device applications. The Cu2+ ion doped ZTC bulk single crystal of dimension 03 × 2.4 × 0.4 cm3 has been grown from pH controlled aqueous solution by employing slow solvent evaporation technique. The structural analysis has been performed by means of single crystal X-ray diffraction technique. The doping of Cu2+ ion in ZTC crystal matrix has been confirmed by means of energy dispersive spectroscopic (EDS) technique. The origin of nonlinear optical properties in Cu2+ ion doped ZTC crystal has been studied by employing the Kurtz-Perry test and Z-scan analysis. The remarkable enhancement in second harmonic generation (SHG) efficiency of Cu2+ ion doped ZTC crystal with reference to ZTC crystal has been determined. The He-Ne laser assisted Z-scan analysis has been performed to determine the third order nonlinear optical (TONLO) nature of grown crystal. The TONLO parameters such as susceptibility, absorption coefficient, refractive index and figure of merit of Cu-ZTC crystal have been evaluated using the Z-scan transmittance data. The laser damage threshold of grown crystal to high intensity of Nd:YAG laser is found to be 706.2 MW/cm2. The hardness number, work hardening index, yield strength and elastic stiffness coefficient of grown crystal has been investigated under microhardness study. The etching study has been carried out to determine the growth likelihood, nature of etch pits and surface quality of grown crystal.

Evaporation Kinetics of Polyol Droplets: Determination of Evaporation Coefficients and Diffusion Constants

NASA Astrophysics Data System (ADS)

Su, Yong-Yang; Marsh, Aleksandra; Haddrell, Allen E.; Li, Zhi-Ming; Reid, Jonathan P.

2017-11-01

In order to quantify the kinetics of mass transfer between the gas and condensed phases in aerosol, physicochemical properties of the gas and condensed phases and kinetic parameters (mass/thermal accommodation coefficients) are crucial for estimating mass fluxes over a wide size range from the free molecule to continuum regimes. In this study, we report measurements of the evaporation kinetics of droplets of 1-butanol, ethylene glycol (EG), diethylene glycol (DEG), and glycerol under well-controlled conditions (gas flow rates and temperature) using the previously developed cylindrical electrode electrodynamic balance technique. Measurements are compared with a model that captures the heat and mass transfer occurring at the evaporating droplet surface. The aim of these measurements is to clarify the discrepancy in the reported values of mass accommodation coefficient (αM, equals to evaporation coefficient based on microscopic reversibility) for 1-butanol, EG, and DEG and improve the accuracy of the value of the diffusion coefficient for glycerol in gaseous nitrogen. The uncertainties in the thermophysical and experimental parameters are carefully assessed, the literature values of the vapor pressures of these components are evaluated, and the plausible ranges of the evaporation coefficients for 1-butanol, EG, and DEG as well as uncertainty in diffusion coefficient for glycerol are reported. Results show that αM should be greater than 0.4, 0.2, and 0.4 for EG, DEG, and 1-butanol, respectively. The refined values are helpful for accurate prediction of the evaporation/condensation rates.

Selective field evaporation in field-ion microscopy for ordered alloys

NASA Astrophysics Data System (ADS)

Ge, Xi-jin; Chen, Nan-xian; Zhang, Wen-qing; Zhu, Feng-wu

1999-04-01

Semiempirical pair potentials, obtained by applying the Chen-inversion technique to a cohesion equation of Rose et al. [Phys. Rev. B 29, 2963 (1984)], are employed to assess the bonding energies of surface atoms of intermetallic compounds. This provides a new calculational model of selective field evaporation in field-ion microscopy (FIM). Based on this model, a successful interpretation of FIM image contrasts for Fe3Al, PtCo, Pt3Co, Ni4Mo, Ni3Al, and Ni3Fe is given.

Synthesis, characterization and application of functional carbon nano materials

NASA Astrophysics Data System (ADS)

Chu, Jin

The synthesis, characterizations and applications of carbon nanomaterials, including carbon nanorods, carbon nanosheets, carbon nanohoneycombs and carbon nanotubes were demonstrated. Different growth techniques such as pulsed laser deposition, DC/RF sputtering, hot filament physical vapour deposition, evaporative casting and vacuum filtration methods were introduced or applied for synthesizing carbon nanomaterials. The morphology, chemical compositions, bond structures, electronic, mechanical and sensing properties of the obtained samples were investigated. Tilted well-aligned carbon micro- and nano- hybrid rods were fabricated on Si at different substrate temperatures and incident angles of carbon source beam using the hot filament physical vapour deposition technique. The morphologic surfaces and bond structures of the oblique carbon rod-like structures were investigated by scanning electron microscopy, field emission scanning electron microscopy, transmission electron diffraction and Raman scattering spectroscopy. The field emission behaviour of the fabricated samples was also tested. Carbon nanosheets and nanohoneycombs were also synthesized on Si substrates using a hot filament physical vapor deposition technique under methane ambient and vacuum, respectively. The four-point Au electrodes are then sputtered on the surface of the nanostructured carbon films to form prototypical humidity sensors. The sensing properties of prototypical sensors at different temperature, humidity, direct current, and alternative current voltage were characterized. Linear sensing response of sensors to relative humidity ranging from 11% to 95% is observed at room temperature. Experimental data indicate that the carbon nanosheets based sensors exhibit an excellent reversible behavior and long-term stability. It also has higher response than that of the humidity sensor with carbon nanohoneycombs materials. Conducting composite films containing carbon nanotubes (CNTs) were prepared in two different ways of evaporative casting and vacuum filtration methods using the biopolymer kappa-carrageenan (KC) as a dispersant. Evaporative casting and vacuum filtration film-formation processes were compared by testing electrical properties. Results showed that films produced using vacuum filtration had higher electrical properties than those prepared using the evaporative casting method. The evaporative casted multi walled carbon nanotubes composite films also performed as the best humidity sensor over all other films measured.

A point implicit time integration technique for slow transient flow problems

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

Kadioglu, Samet Y.; Berry, Ray A.; Martineau, Richard C.

2015-05-01

We introduce a point implicit time integration technique for slow transient flow problems. The method treats the solution variables of interest (that can be located at cell centers, cell edges, or cell nodes) implicitly and the rest of the information related to same or other variables are handled explicitly. The method does not require implicit iteration; instead it time advances the solutions in a similar spirit to explicit methods, except it involves a few additional function(s) evaluation steps. Moreover, the method is unconditionally stable, as a fully implicit method would be. This new approach exhibits the simplicity of implementation ofmore » explicit methods and the stability of implicit methods. It is specifically designed for slow transient flow problems of long duration wherein one would like to perform time integrations with very large time steps. Because the method can be time inaccurate for fast transient problems, particularly with larger time steps, an appropriate solution strategy for a problem that evolves from a fast to a slow transient would be to integrate the fast transient with an explicit or semi-implicit technique and then switch to this point implicit method as soon as the time variation slows sufficiently. We have solved several test problems that result from scalar or systems of flow equations. Our findings indicate the new method can integrate slow transient problems very efficiently; and its implementation is very robust.« less

Abrupt change of Antarctic moisture origin at the end of Termination II

PubMed Central

Masson-Delmotte, V.; Stenni, B.; Blunier, T.; Cattani, O.; Chappellaz, J.; Cheng, H.; Dreyfus, G.; Edwards, R. L.; Falourd, S.; Govin, A.; Kawamura, K.; Johnsen, S. J.; Jouzel, J.; Landais, A.; Lemieux-Dudon, B.; Lourantou, A.; Marshall, G.; Minster, B.; Mudelsee, M.; Pol, K.; Röthlisberger, R.; Selmo, E.; Waelbroeck, C.

2010-01-01

The deuterium excess of polar ice cores documents past changes in evaporation conditions and moisture origin. New data obtained from the European Project for Ice Coring in Antarctica Dome C East Antarctic ice core provide new insights on the sequence of events involved in Termination II, the transition between the penultimate glacial and interglacial periods. This termination is marked by a north–south seesaw behavior, with first a slow methane concentration rise associated with a strong Antarctic temperature warming and a slow deuterium excess rise. This first step is followed by an abrupt north Atlantic warming, an abrupt resumption of the East Asian summer monsoon, a sharp methane rise, and a CO2 overshoot, which coincide within dating uncertainties with the end of Antarctic optimum. Here, we show that this second phase is marked by a very sharp Dome C centennial deuterium excess rise, revealing abrupt reorganization of atmospheric circulation in the southern Indian Ocean sector. PMID:20566887

Modelling sub-daily evaporation from a small reservoir.

NASA Astrophysics Data System (ADS)

McGloin, Ryan; McGowan, Hamish; McJannet, David; Burn, Stewart

2013-04-01

Accurate quantification of evaporation from small water storages is essential for water management and is also required as input in some regional hydrological and meteorological models. Global estimates of the number of small storages or lakes (< 0.1 kilometers) are estimated to be in the order of 300 million (Downing et al., 2006). However, direct evaporation measurements at small reservoirs using the eddy covariance or scintillometry techniques have been limited due to their expensive and complex nature. To correctly represent the effect that small water bodies have on the regional hydrometeorology, reliable estimates of sub-daily evaporation are necessary. However, evaporation modelling studies at small reservoirs have so far been limited to quantifying daily estimates. In order to ascertain suitable methods for accurately modelling hourly evaporation from a small reservoir, this study compares evaporation results measured by the eddy covariance method at a small reservoir in southeast Queensland, Australia, to results from several modelling approaches using both over-water and land-based meteorological measurements. Accurate predictions of hourly evaporation were obtained by a simple theoretical mass transfer model requiring only over-water measurements of wind speed, humidity and water surface temperature. An evaporation model that was recently developed for use in small reservoir environments by Granger and Hedstrom (2011), appeared to overestimate the impact stability had on evaporation. While evaporation predictions made by the 1-dimensional hydrodynamics model, DYRESM (Dynamic Reservoir Simulation Model) (Imberger and Patterson, 1981), showed reasonable agreement with measured values. DYRESM did not show any substantial improvement in evaporation prediction when inflows and out flows were included and only a slighter better correlation was shown when over-water meteorological measurements were used in place of land-based measurements. Downing, J. A., Y. T. Prairie, J. J. Cole, C. M. Duarte, L. J. Tranvik, R. G. Striegl, W. H. McDowell, P. Kortelainen, N. F. Caraco, J. M. Melack and J. J. Middelburg (2006), The global abundance and size distribution of lakes, ponds, and impoundments, Limnology and Oceanography, 51, 2388-2397. Granger, R.J. and N. Hedstrom (2011), Modelling hourly rates of evaporation from small lakes, Hydrological and Earth System Sciences, 15, doi:10.5194/hess-15-267-2011. Imberger, J. and J.C. Patterson (1981), Dynamic Reservoir Simulation Model - DYRESM: 5, In: Transport Models for Inland and Coastal Waters. H.B. Fischer (Ed.). Academic Press, New York, 310-361.

Capillary evaporation of the ionic liquid [EMIM][BF4] in nanoscale solvophobic confinement

NASA Astrophysics Data System (ADS)

Shrivastav, Gourav; Remsing, Richard C.; Kashyap, Hemant K.

2018-05-01

Solvent density fluctuations play a crucial role in liquid-vapor transitions in solvophobic confinement and can also be important for understanding solvation of polar and apolar solutes. In the case of ionic liquids (ILs), density fluctuations can be used to understand important processes in the context of nanoscale aggregation and colloidal self-assemblies. In this article, we explore the nature of density fluctuations associated with capillary evaporation of the IL 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]) in the confined region of model solvophobic nanoscale sheets by using molecular dynamics simulations combined with non-Boltzmann sampling techniques. We demonstrate that density fluctuations of the confined IL play an important role in capillary evaporation, suggesting analogies to dewetting transitions involving water. Significant changes in the interfacial structure of the IL are also detailed and suggested to underlie a non-classical (non-parabolic) dependence of the free energy barrier to evaporation on the degree of confinement.

Evaporation from a meniscus within a capillary tube in microgravity

NASA Technical Reports Server (NTRS)

Hallinan, K. P.

1993-01-01

The following represents a summary of progress made on the project 'Evaporation from a Capillary Meniscus in Microgravity' being conducted at the University of Dayton during the period 1 Dec. 1992 to 30 Nov. 1993. The efforts during this first year of the grant focused upon the following specific tasks: (1) application of a 3-D scattering particle image velocimetry technique to thin film velocity field measurement; (2) modeling the thermo-fluid behavior of the evaporating meniscus in 0-g within large diameter capillaries; (3) conceptualization of the space flight test cell (loop) configuration; (4) construction of prototypes of the test loop configuration; (5) conduct of experiments in 0-g in the 2.2 second drop tower at NASA-LeRC to study evaporation from a capillary meniscus within a square cuvette; and (6) investigation of the effect of vibrations on the stability of the meniscus. An overview of the work completed within these six task areas is presented.

Ethanol gas sensor based upon ZnO nanoparticles prepared by different techniques

NASA Astrophysics Data System (ADS)

Bhatia, Sonik; Verma, Neha; Bedi, R. K.

Nowadays, applications of nanosized materials have been an important issue in basic and applied sciences. In this investigation, Zinc Oxide (ZnO) nanoparticles were prepared by two different techniques (simple heat treatment, thermal evaporation-two zone furnaces). In order to control shape and size - ZnO nanoparticles prepared from heat treatment were used as a source for thermal evaporation method by using two zone split furnace by varying zone temperature (Zone 1-800 °C and Zone 2-400 °C). For both techniques 0.17 M of Zn acetate dihydrate is used as main precursor and film is deposited on glass substrate. Synthesized ZnO were characterized for XRD, FESEM, FTIR and UV-Vis spectrophotometer and LCR meter. XRD revealed hexagonal wurtzite structure with preferential orientation along (1 0 1) plane. FESEM observed that grain size in the range of range of ∼50 ± 5 nm. FTIR spectra showed that the peaks between 400 and 500 cm-1 for ZnO stretching modes. Optical properties has been studied and found that the observed band gap lies in the range of 3.32-3.36 eV. The higher value of capacitance is observed at lower frequency. Gas sensing properties showed the higher response in case of thermal evaporation as compared to simple heat treatment at an operating temperature of 250 °C.

Evaporation of liquid droplets of nano- and micro-meter size as a function of molecular mass and intermolecular interactions: experiments and molecular dynamics simulations.

PubMed

Hołyst, Robert; Litniewski, Marek; Jakubczyk, Daniel

2017-09-13

Transport of heat to the surface of a liquid is a limiting step in the evaporation of liquids into an inert gas. Molecular dynamics (MD) simulations of a two component Lennard-Jones (LJ) fluid revealed two modes of energy transport from a vapour to an interface of an evaporating droplet of liquid. Heat is transported according to the equation of temperature diffusion, far from the droplet of radius R. The heat flux, in this region, is proportional to temperature gradient and heat conductivity in the vapour. However at some distance from the interface, Aλ, (where λ is the mean free path in the gas), the temperature has a discontinuity and heat is transported ballistically i.e. by direct individual collisions of gas molecules with the interface. This ballistic transport reduces the heat flux (and consequently the mass flux) by the factor R/(R + Aλ) in comparison to the flux obtained from temperature diffusion. Thus it slows down the evaporation of droplets of sizes R ∼ Aλ and smaller (practically for sizes from 10 3 nm down to 1 nm). We analyzed parameter A as a function of interactions between molecules and their masses. The rescaled parameter, A(k B T b /ε 11 ) 1/2 , is a linear function of the ratio of the molecular mass of the liquid molecules to the molecular mass of the gas molecules, m 1 /m 2 (for a series of chemically similar compounds). Here ε 11 is the interaction parameter between molecules in the liquid (proportional to the enthalpy of evaporation) and T b is the temperature of the gas in the bulk. We tested the predictions of MD simulations in experiments performed on droplets of ethylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol. They were suspended in an electrodynamic trap and evaporated into dry nitrogen gas. A changes from ∼1 (for ethylene glycol) to approximately 10 (for tetraethylene glycol) and has the same dependence on molecular parameters as obtained for the LJ fluid in MD simulations. The value of x = A(k B T b /ε 11 ) 1/2 is of the order of 1 (for water x = 1.8, glycerol x = 1, ethylene glycol x = 0.4, tetraethylene glycol x = 2.1 evaporating into dry nitrogen at room temperature and for Lennard-Jones fluids x = 2 for m 1 /m 2 = 1 and low temperature).

Gastric dysrhythmias and the current status of electrogastrography

NASA Technical Reports Server (NTRS)

Koch, K. L.

1989-01-01

Myoelectrical activity recorded simultaneously from mucosal, serosal, and cutaneous electrodes has confirmed that the 3-cpm signal from such electrodes reflects gastric slow-wave activity. Now, the observation that patients with unexplained nausea and vomiting may have very rapid slow-wave frequencies (tachygastrias) and very slow, slow-wave frequencies (bradygastrias) suggests that electrogastrography, a reliable and noninvasive technique, may be useful in the diagnosis and management of patients with upper abdominal symptoms and gastroparesis.

Dendronization-induced phase-transfer, stabilization and self-assembly of large colloidal Au nanoparticles

NASA Astrophysics Data System (ADS)

Malassis, Ludivine; Jishkariani, Davit; Murray, Christopher B.; Donnio, Bertrand

2016-07-01

The phase-transfer of CTAB-coated aqueous, spherical gold nanoparticles, with metallic core diameters ranging from ca. 27 to 54 nm, into organic solvents by exchanging the primitive polar bilayer with lipophilic, disulfide dendritic ligands is reported. The presence of such a thick nonpolar organic shell around these large nanoparticles enhances their stabilization against aggregation, in addition to enabling their transfer into a variety of solvents such as chloroform, toluene or tetrahydrofuran. Upon the slow evaporation of a chloroform suspension deposited on a solid support, the dendronized hybrids were found to self-assemble into ring structures of various diameters. Moreover, their self-assembly at the liquid-air interface affords the formation of fairly long-range ordered monolayers, over large areas, that can then be entirely transferred onto solid substrates.The phase-transfer of CTAB-coated aqueous, spherical gold nanoparticles, with metallic core diameters ranging from ca. 27 to 54 nm, into organic solvents by exchanging the primitive polar bilayer with lipophilic, disulfide dendritic ligands is reported. The presence of such a thick nonpolar organic shell around these large nanoparticles enhances their stabilization against aggregation, in addition to enabling their transfer into a variety of solvents such as chloroform, toluene or tetrahydrofuran. Upon the slow evaporation of a chloroform suspension deposited on a solid support, the dendronized hybrids were found to self-assemble into ring structures of various diameters. Moreover, their self-assembly at the liquid-air interface affords the formation of fairly long-range ordered monolayers, over large areas, that can then be entirely transferred onto solid substrates. Electronic supplementary information (ESI) available: TEM microscope images. See DOI: 10.1039/c6nr03404g

Multi-walled carbon nanotube structural instability with/without metal nanoparticles under electron beam irradiation

NASA Astrophysics Data System (ADS)

Khan, Imran; Huang, Shengli; Wu, Chenxu

2017-12-01

The structural transformation of multi-walled carbon nanotubes (MWCNT) under electron beam (e-beam) irradiation at room temperature is studied, with respect to a novel passivation effect due to gold nanoparticles (Au NPs). MWCNT structural evolution induced by energetic e-beam irradiation leads to faster shrinkage, as revealed via in situ transmission electron microscopy, while MWCNT surface modification with Au NPs (Au-MWCNT) slows down the shrinkage by impeding the structural evolution process for a prolonged time under the same irradiation conditions. The new relationship between MWCNT and Au-MWCNT shrinking radii and irradiation time illustrates that the MWCNT shrinkage rate is faster than either theoretical predictions or the same process in Au-MWCNTs. As compared with the outer surface energy (positive curvature), the inner surface energy (negative curvature) of the MWCNT contributes more to the athermal evaporation of tube wall atoms, leading to structural instability and shrinkage under e-beam irradiation. Conversely, Au NPs possess only outer surface energy (positive curvature) compared with the MWCNT. Their presence on MWCNT surfaces retards the dynamics of MWCNT structural evolution by slowing down the evaporation process of carbon atoms, thus restricting Au-MWCNT shrinkage. Au NP interaction and growth evolves athermally on MWCNT surfaces, exhibits increase in their size, and indicates the association of this mechanism with the coalescence induced by e-beam activated electronic excitations. Despite their growth, Au NPs show extreme structural stability, and remain crystalline under prolonged irradiation. It is proposed that the surface energy of MWCNTs and Au NPs, together with e-beam activated soft modes or lattice instability effects, predominantly govern all the above varieties of structural evolution.

Design of evaporative-cooling roof for decreasing air temperatures in buildings in the humid tropics

NASA Astrophysics Data System (ADS)

Kindangen, Jefrey I.; Umboh, Markus K.

2017-03-01

This subject points to assess the benefits of the evaporative-cooling roof, particularly for buildings with corrugated zinc roofs. In Manado, many buildings have roofed with corrugated zinc sheets; because this material is truly practical, easy and economical application. In general, to achieve thermal comfort in buildings in a humid tropical climate, people applying cross ventilation to cool the air in the room and avoid overheating. Cross ventilation is a very popular path to achieve thermal comfort; yet, at that place are other techniques that allow reducing the problem of excessive high temperature in the room in the constructions. This study emphasizes applications of the evaporative-cooling roof. Spraying water on the surface of the ceiling has been executed on the test cell and the reuse of water after being sprayed and cooled once more by applying a heat exchanger. Initial results indicate a reliable design and successfully meet the target as an effective evaporative-cooling roof technique. Application of water spraying automatic and cooling water installations can work optimally and can be an optimal model for the cooling roof as one of the green technologies. The role of heat exchangers can lower the temperature of the water from spraying the surface of the ceiling, which has become a hot, down an average of 0.77° C. The mass flow rate of the cooling water is approximately 1.106 kg/h and the rate of heat flow is around 515 Watt, depend on the site.

Studying biofuel aerosol evaporation rates with single particle manipulation

NASA Astrophysics Data System (ADS)

Corsetti, S.; Miles, R. E. H.; Reid, J. P.; Kiefer, J.; McGloin, D.

2014-09-01

The significant increase in the air pollution, and the impact on climate change due to the burning of fossil fuel has led to the research of alternative energies. Bio-ethanol obtained from a variety of feedstocks can provide a feasible solution. Mixing bio-ethanol with gasoline leads to a reduction in CO emission and in NOx emissions compared with the use of gasoline alone. However, adding ethanol leads to a change in the fuel evaporation. Here we present a preliminary investigation of evaporation times of single ethanol-gasoline droplets. In particular, we investigated the different evaporation rate of the droplets depending on the variation in the percentage of ethanol inside them. Two different techniques have been used to trap the droplets. One makes use of a 532nm optical tweezers set up, the other of an electrodynamics balance (EDB). The droplets decreasing size was measured using video analysis and elastic light scattering respectively. In the first case measurements were conducted at 293.15 K and ambient humidity. In the second case at 280.5 K and a controlled environment has been preserved by flowing nitrogen into the chamber. Binary phase droplets with a higher percentage of ethanol resulted in longer droplet lifetimes. Our work also highlights the advantages and disadvantages of each technique for such studies. In particular it is challenging to trap droplets with low ethanol content (such as pure gasoline) by the use of EDB. Conversely such droplets are trivial to trap using optical tweezers.

Growth of copper-zinc and copper-magnesium particles by gas-evaporation technique

NASA Astrophysics Data System (ADS)

Ohno, T.

1984-12-01

Fine particles of Cu-Zn and Cu-Mg systems of diameter less than 500 nm were prepared by evaporating the constituent metals simultaneously from two evaporation sources in an atmosphere of argon of 10 to 30 Torr. The composition, crystal structure and habit of the alloy particles were investigated by electron microscopy. The composition of the alloy particles varied depending on the growth zone of metal smoke and almost all phases known in Cu-Zn or Cu-Mg system were found at the same time. The particles with single phase showed generally well-defined crystal habits characteristic of their crystal structures. For the particles with two phases, a fixed lattice relation between the two phases was generally recognized. The formation process of the alloy particles is discussed through these observations.

Extreme ultraviolet reflection efficiencies of diamond-turned aluminum, polished nickel, and evaporated gold surfaces. [for telescope mirrors

NASA Technical Reports Server (NTRS)

Malina, R. F.; Cash, W.

1978-01-01

Measured reflection efficiencies are presented for flat samples of diamond-turned aluminum, nickel, and evaporated gold surfaces fabricated by techniques suited for EUV telescopes. The aluminum samples were 6.2-cm-diameter disks of 6061-T6, the electroless nickel samples were formed by plating beryllium disks with 7.5-microns of Kanigen. Gold samples were produced by coating the aluminum and nickel samples with 5 strips of evaporated gold. Reflection efficiencies are given for grazing angles in the 5-75 degree range. The results indicate that for wavelengths over about 100 A, the gold-coated nickel samples yield highest efficiencies. For shorter wavelengths, the nickel samples yield better efficiencies. 500 A is found to be the optimal gold thickness.

Laser absorption-scattering technique applied to asymmetric evaporating fuel sprays for simultaneous measurement of vapor/liquid mass distributions

NASA Astrophysics Data System (ADS)

Gao, J.; Nishida, K.

2010-10-01

This paper describes an Ultraviolet-Visible Laser Absorption-Scattering (UV-Vis LAS) imaging technique applied to asymmetric fuel sprays. Continuing from the previous studies, the detailed measurement principle was derived. It is demonstrated that, by means of this technique, cumulative masses and mass distributions of vapor/liquid phases can be quantitatively measured no matter what shape the spray is. A systematic uncertainty analysis was performed, and the measurement accuracy was also verified through a series of experiments on the completely vaporized fuel spray. The results show that the Molar Absorption Coefficient (MAC) of the test fuel, which is typically pressure and temperature dependent, is the major error source. The measurement error in the vapor determination has been shown to be approximately 18% under the assumption of constant MAC of the test fuel. Two application examples of the extended LAS technique were presented for exploring the dynamics and physical insight of the evaporating fuel sprays: diesel sprays injected by group-hole nozzles and gasoline sprays impinging on an inclined wall.

New gap-filling and partitioning technique for H2O eddy fluxes measured over forests

NASA Astrophysics Data System (ADS)

Kang, Minseok; Kim, Joon; Malla Thakuri, Bindu; Chun, Junghwa; Cho, Chunho

2018-01-01

The continuous measurement of H2O fluxes using the eddy covariance (EC) technique is still challenging for forests because of large amounts of wet canopy evaporation (EWC), which occur during and following rain events when the EC systems rarely work correctly. We propose a new gap-filling and partitioning technique for the H2O fluxes: a model-statistics hybrid (MSH) method. It enables the recovery of the missing EWC in the traditional gap-filling method and the partitioning of the evapotranspiration (ET) into transpiration and (wet canopy) evaporation. We tested and validated the new method using the data sets from two flux towers, which are located at forests in hilly and complex terrains. The MSH reasonably recovered the missing EWC of 16-41 mm yr-1 and separated it from the ET (14-23 % of the annual ET). Additionally, we illustrated certain advantages of the proposed technique which enable us to understand better how ET responds to environmental changes and how the water cycle is connected to the carbon cycle in a forest ecosystem.

Estimation of evaporation from open water - A review of selected studies, summary of U.S. Army Corps of Engineers data collection and methods, and evaluation of two methods for estimation of evaporation from five reservoirs in Texas

USGS Publications Warehouse

Harwell, Glenn R.

2012-01-01

Organizations responsible for the management of water resources, such as the U.S. Army Corps of Engineers (USACE), are tasked with estimation of evaporation for water-budgeting and planning purposes. The USACE has historically used Class A pan evaporation data (pan data) to estimate evaporation from reservoirs but many USACE Districts have been experimenting with other techniques for an alternative to collecting pan data. The energy-budget method generally is considered the preferred method for accurate estimation of open-water evaporation from lakes and reservoirs. Complex equations to estimate evaporation, such as the Penman, DeBruin-Keijman, and Priestley-Taylor, perform well when compared with energy-budget method estimates when all of the important energy terms are included in the equations and ideal data are collected. However, sometimes nonideal data are collected and energy terms, such as the change in the amount of stored energy and advected energy, are not included in the equations. When this is done, the corresponding errors in evaporation estimates are not quantifiable. Much simpler methods, such as the Hamon method and a method developed by the U.S. Weather Bureau (USWB) (renamed the National Weather Service in 1970), have been shown to provide reasonable estimates of evaporation when compared to energy-budget method estimates. Data requirements for the Hamon and USWB methods are minimal and sometimes perform well with remotely collected data. The Hamon method requires average daily air temperature, and the USWB method requires daily averages of air temperature, relative humidity, wind speed, and solar radiation. Estimates of annual lake evaporation from pan data are frequently within 20 percent of energy-budget method estimates. Results of evaporation estimates from the Hamon method and the USWB method were compared against historical pan data at five selected reservoirs in Texas (Benbrook Lake, Canyon Lake, Granger Lake, Hords Creek Lake, and Sam Rayburn Lake) to evaluate their performance and to develop coefficients to minimize bias for the purpose of estimating reservoir evaporation with accuracies similar to estimates of evaporation obtained from pan data. The modified Hamon method estimates of reservoir evaporation were similar to estimates of reservoir evaporation from pan data for daily, monthly, and annual time periods. The modified Hamon method estimates of annual reservoir evaporation were always within 20 percent of annual reservoir evaporation from pan data. Unmodified and modified USWB method estimates of annual reservoir evaporation were within 20 percent of annual reservoir evaporation from pan data for about 91 percent of the years compared. Average daily differences between modified USWB method estimates and estimates from pan data as a percentage of the average amount of daily evaporation from pan data were within 20 percent for 98 percent of the months. Without any modification to the USWB method, average daily differences as a percentage of the average amount of daily evaporation from pan data were within 20 percent for 73 percent of the months. Use of the unmodified USWB method is appealing because it means estimates of average daily reservoir evaporation can be made from air temperature, relative humidity, wind speed, and solar radiation data collected from remote weather stations without the need to develop site-specific coefficients from historical pan data. Site-specific coefficients would need to be developed for the modified version of the Hamon method.

Evaporation variability of Nam Co Lake in the Tibetan Plateau and its role in recent rapid lake expansion

NASA Astrophysics Data System (ADS)

Ma, Ning; Szilagyi, Jozsef; Niu, Guo-Yue; Zhang, Yinsheng; Zhang, Teng; Wang, Binbin; Wu, Yanhong

2016-06-01

Previous studies have shown that the majority of the lakes in the Tibetan Plateau (TP) started to expand rapidly since the late 1990s. However, the causes are still not well known. For Nam Co, being a closed lake with no outflow, evaporation (EL) over the lake surface is the only way water may leave the lake. Therefore, quantifying EL is key for investigating the mechanism of lake expansion in the TP. EL can be quantified by Penman- and/or bulk-transfer-type models, requiring only net radiation, temperature, humidity and wind speed for inputs. However, interpolation of wind speed data may be laden with great uncertainty due to extremely sparse ground meteorological observations, the highly heterogeneous landscape and lake-land breeze effects. Here, evaporation of Nam Co Lake was investigated within the 1979-2012 period at a monthly time-scale using the complementary relationship lake evaporation (CRLE) model which does not require wind speed data. Validations by in-situ observations of E601B pan evaporation rates at the shore of Nam Co Lake as well as measured EL over an adjacent small lake using eddy covariance technique suggest that CRLE is capable of simulating EL well since it implicitly considers wind effects on evaporation via its vapor transfer coefficient. The multi-year average of annual evaporation of Nam Co Lake is 635 mm. From 1979 to 2012, annual evaporation of Nam Co Lake expressed a very slight decreasing trend. However, a more significant decrease in EL occurred during 1998-2008 at a rate of -12 mm yr-1. Based on water-level readings, this significant decrease in lake evaporation was found to be responsible for approximately 4% of the reported rapid water level increase and areal expansion of Nam Co Lake during the same period.

Slow crack growth in spinel in water

NASA Technical Reports Server (NTRS)

Schwantes, S.; Elber, W.

1983-01-01

Magnesium aluminate spinel was tested in a water environment at room temperature to establish its slow crack-growth behavior. Ring specimens with artificial flaws on the outside surface were loaded hydraulically on the inside surface. The time to failure was measured. Various precracking techniques were evaluated and multiple precracks were used to minimize the scatter in the static fatigue tests. Statistical analysis techniques were developed to determine the strength and crack velocities for a single flaw. Slow crack-growth rupture was observed at stress intensities as low as 70 percent of K sub c. A strengthening effect was observed in specimens that had survived long-time static fatigue tests.

PHEA-PLA biocompatible nanoparticles by technique of solvent evaporation from multiple emulsions.

PubMed

Cavallaro, Gennara; Craparo, Emanuela Fabiola; Sardo, Carla; Lamberti, Gaetano; Barba, Anna Angela; Dalmoro, Annalisa

2015-11-30

Nanocarriers of amphiphilic polymeric materials represent versatile delivery systems for poorly water soluble drugs. In this work the technique of solvent evaporation from multiple emulsions was applied to produce nanovectors based on new amphiphilic copolymer, the α,β-poly(N-2-hydroxyethyl)-DL-aspartamide-polylactic acid (PHEA-PLA), purposely synthesized to be used in the controlled release of active molecules poorly soluble in water. To this aim an amphiphilic derivative of PHEA, a hydrophilic polymer, was synthesized by derivatization of the polymeric backbone with hydrophobic grafts of polylactic acid (PLA). The achieved copolymer was thus used to produce nanoparticles loaded with α tocopherol (vitamin E) adopted as lipophilic model molecule. Applying a protocol based on solvent evaporation from multiple emulsions assisted by ultrasonic energy and optimizing the emulsification process (solvent selection/separation stages), PHEA-PLA nanostructured particles with total α tocopherol entrapment efficiency (100%), were obtained. The drug release is expected to take place in lower times with respect to PLA due to the presence of the hydrophilic PHEA, therefore the produced nanoparticles can be used for semi-long term release drug delivery systems. Copyright © 2015 Elsevier B.V. All rights reserved.

Multiphonon Raman scattering and photoluminescence studies of CdS nanocrystals grown by thermal evaporation

NASA Astrophysics Data System (ADS)

Farid, Sidra; Stroscio, Michael A.; Dutta, Mitra

2018-03-01

Thermal evaporation growth technique is presented as a route to grow cost effective high quality CdS thin films. We have successfully grown high quality CdS thin films on ITO coated glass substrates by thermal evaporation technique and analyzed the effects of annealing and excitation dependent input of CdS thin film using Raman and photoluminescence spectroscopy. LO phonon modes have been analyzed quantitatively considering the contributions due to anneal induced effects on film quality using phonon spatial correlation model, line shape and defect state analysis. Asymmetry in the Raman line shape towards the low frequency side is related to the phonon confinement effects and is modeled by spatial correlation model. Calculations of width (FWHM), integrated intensity, and line shape for the longitudinal (LO) optical phonon modes indicate improved crystalline quality for the annealed films as compared to the as grown films. With increase in laser power, intensity ratio of 2-LO to 1-LO optical phonon modes is found to increase while multiple overtones upto fourth order are observed. Power dependent photoluminescence data indicates direct band-to-band transition in CdS thin films.

Exact nonlinear model reduction for a von Kármán beam: Slow-fast decomposition and spectral submanifolds

NASA Astrophysics Data System (ADS)

Jain, Shobhit; Tiso, Paolo; Haller, George

2018-06-01

We apply two recently formulated mathematical techniques, Slow-Fast Decomposition (SFD) and Spectral Submanifold (SSM) reduction, to a von Kármán beam with geometric nonlinearities and viscoelastic damping. SFD identifies a global slow manifold in the full system which attracts solutions at rates faster than typical rates within the manifold. An SSM, the smoothest nonlinear continuation of a linear modal subspace, is then used to further reduce the beam equations within the slow manifold. This two-stage, mathematically exact procedure results in a drastic reduction of the finite-element beam model to a one-degree-of freedom nonlinear oscillator. We also introduce the technique of spectral quotient analysis, which gives the number of modes relevant for reduction as output rather than input to the reduction process.

Slowing techniques for loading a magneto-optical trap of CaF molecules

NASA Astrophysics Data System (ADS)

Truppe, Stefan; Fitch, Noah; Williams, Hannah; Hambach, Moritz; Sauer, Ben; Hinds, Ed; Tarbutt, Mike

2016-05-01

Ultracold molecules in a magneto-optical trap (MOT) are useful for testing fundamental physics and studying strongly-interacting quantum systems. With experiments starting with a relatively fast (50-200 m/s) buffer-gas beam, a primary concern is decelerating molecules to below the MOT capture velocity, typically 10 m/s. Direct laser cooling, where the molecules are slowed via momentum transfer from a chirped counter-propagating narrowband laser, is a natural choice. However, chirping the cooling and repump lasers requires precise control of multiple laser frequencies simultaneously. Another approach, called ``white-light slowing'' uses a broadband laser such that all fast molecules in the beam are decelerated. By addressing numerous velocities no chirping is needed. Unfortunately, both techniques have significant losses as molecules are transversely heated during the optical cycling. Ideally, the slowing method would provide simultaneous deceleration and transverse guiding. A newly developed technique, called Zeeman-Sisyphus deceleration, is potentially capable of both. Using permanent magnets and optical pumping, the number of scattered photons is reduced, lessening transverse heating and relaxing the repump requirements. Here we compare all three options for CaF.

First demonstration of the fast-to-slow corrector current shift in the NSLS-II storage ring

DOE PAGES

Yang, Xi; Tian, Yuke; Yu, Li Hua; ...

2018-04-01

In order to realize the full benefits of the high brightness and ultra-small beam sizes of NSLS-II, it is essential that the photon beams are exceedingly stable. In the circumstances of implementing local bumps, changing ID gaps, and long term drifting, the fast orbit feedback (FOFB) requires shifting the fast corrector strengths to the slow correctors to prevent the fast corrector saturation and to make the beam orbit stable in the sub-micron level. As the result, a reliable and precise technique of fast-to-slow corrector strength shift has been developed and tested at NSLS-II. This technique is based on the fastmore » corrector response to the slow corrector change when the FOFB is on. In this article, the shift technique is described and the result of proof-of-principle experiment carried out at NSLS-II is presented. The maximum fast corrector current was reduced from greater than 0.45 A to less than 0.04 A with the orbit perturbation within ±1 μm.« less

First demonstration of the fast-to-slow corrector current shift in the NSLS-II storage ring

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

Yang, Xi; Tian, Yuke; Yu, Li Hua

In order to realize the full benefits of the high brightness and ultra-small beam sizes of NSLS-II, it is essential that the photon beams are exceedingly stable. In the circumstances of implementing local bumps, changing ID gaps, and long term drifting, the fast orbit feedback (FOFB) requires shifting the fast corrector strengths to the slow correctors to prevent the fast corrector saturation and to make the beam orbit stable in the sub-micron level. As the result, a reliable and precise technique of fast-to-slow corrector strength shift has been developed and tested at NSLS-II. This technique is based on the fastmore » corrector response to the slow corrector change when the FOFB is on. In this article, the shift technique is described and the result of proof-of-principle experiment carried out at NSLS-II is presented. The maximum fast corrector current was reduced from greater than 0.45 A to less than 0.04 A with the orbit perturbation within ±1 μm.« less

The advantages, and challenges, in using multiple techniques in the estimation of surface water-groundwater fluxes.

NASA Astrophysics Data System (ADS)

Shanafield, M.; Cook, P. G.

2014-12-01

When estimating surface water-groundwater fluxes, the use of complimentary techniques helps to fill in uncertainties in any individual method, and to potentially gain a better understanding of spatial and temporal variability in a system. It can also be a way of preventing the loss of data during infrequent and unpredictable flow events. For example, much of arid Australia relies on groundwater, which is recharged by streamflow through ephemeral streams during flood events. Three recent surface water/groundwater investigations from arid Australian systems provide good examples of how using multiple field and analysis techniques can help to more fully characterize surface water-groundwater fluxes, but can also result in conflicting values over varying spatial and temporal scales. In the Pilbara region of Western Australia, combining streambed radon measurements, vertical heat transport modeling, and a tracer test helped constrain very low streambed residence times, which are on the order of minutes. Spatial and temporal variability between the methods yielded hyporheic exchange estimates between 10-4 m2 s-1 and 4.2 x 10-2 m2 s-1. In South Australia, three-dimensional heat transport modeling captured heterogeneity within 20 square meters of streambed, identifying areas of sandy soil (flux rates of up to 3 m d-1) and clay (flux rates too slow to be accurately characterized). Streamflow front modeling showed similar flux rates, but averaged over 100 m long stream segments for a 1.6 km reach. Finally, in central Australia, several methods are used to decipher whether any of the flow down a highly ephemeral river contributes to regional groundwater recharge, showing that evaporation and evapotranspiration likely accounts for all of the infiltration into the perched aquifer. Lessons learned from these examples demonstrate the influences of the spatial and temporal variability between techniques on estimated fluxes.

Growth, optical, luminescence, thermal and mechanical behavior of an organic single crystal: 3-Acetyl-2-methyl-4-phenylquinolin-1-ium chloride.

PubMed

Nirosha, M; Kalainathan, S; Sarveswari, S; Vijayakumar, V

2014-04-05

A single crystal of 3-acetyl-2-methyl-4-phenylquinolin-1-ium chloride has grown by slow evaporation solution growth technique using ethanol as solvent. The structural, thermal, optical and mechanical property has studied for the grown crystal. Single crystal XRD revealed that the crystal belongs to monoclinic system with space group P21/c. The presences of Functional groups in the crystallized material have confirmed using the FTIR vibrational spectrum. The optical absorbance spectrum recorded from 190 to 1100nm shows the cut-off wavelength occurs at 371nm. The material shows its transparency in the entire region of the visible spectrum. The photoluminescence spectrum shows the ultraviolet and blue emission in the crystal. Thermogravimetric and differential thermal analysis reveal the thermal stability of the grown crystal. Etching study shows the grown mechanism and surface features of the crystal. Vickers microhardness studies have carried out on the (01-1) plane to understand the mechanical properties of the grown crystal. The hardness of the title compound increases on increasing the load. The Meyer's index number (n), and the stiffness constants for different loads has calculated and reported. Copyright © 2013 Elsevier B.V. All rights reserved.

Synthesis, characterization, crystal structure and theoretical studies of 4-[(E)-(3-chloro-4-hydroxyphenyl) diazenyl]-1, 5-dimethyl-2-phenyl-1, 2-dihydro-3H-pyrazol-3-one

NASA Astrophysics Data System (ADS)

Athira, L. S.; Lakshmi, C. S. Nair; Balachandran, S.; Arul Dhas, D.; Hubert Joe, I.

2017-11-01

Crystals of new heterocyclic azo compound of 4-aminoantipyrine, 4-[(E)-(3-chloro-4-hydroxyphenyl)diazenyl]-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one have been grown by slow evaporation method at room temperature and its structural characterization was performed by X- ray diffraction method. The spectroscopic characterization was also performed by FT-IR, UV-Vis, 13C and 1H NMR techniques. The compound crystallizes in the monoclinic CC space group with cell dimensions a = 12.4842 (13), b = 16.4492 (16), c = 8.3389 (8) and β = 102.698 (3)°. The phenyl ring attached to the pyrazolone moiety is disordered over two positions with an occupancy ratio 52:48. The components of the disorder were refined. DFT calculations have been performed by using B3LYP/6-311G (d,p) level basis set. The calculated vibrational frequency showed a red shift for Cdbnd O and OH stretching. The natural bond orbital analysis of monomer, dimer and trimer structures reveals the absence of intramolecular hydrogen bonding; however intermolecular hydrogen bonding is observed. The cationic and anionic reactive sites of compound have been visualized on MEP surface.

PLGA nanoparticles as chlorhexidine-delivery carrier to resin-dentin adhesive interface.

PubMed

Priyadarshini, Balasankar Meera; Mitali, Kakran; Lu, Thong Beng; Handral, Harish K; Dubey, Nileshkumar; Fawzy, Amr S

2017-07-01

To characterize and deliver fabricated CHX-loaded PLGA-nanoparticles inside micron-sized dentinal-tubules of demineralized dentin-substrates and resin-dentin interface. Nanoparticles fabricated by emulsion evaporation were assessed in-vitro by different techniques. Delivery of drug-loaded nanoparticles to demineralized dentin substrates, interaction with collagen matrix, and ex-vivo CHX-release profiles using extracted teeth connected to experimental setup simulating pulpal hydrostatic pressure were investigated. Furthermore, nanoparticles association/interaction with a commercial dentin-adhesive applied to demineralized dentin substrates were examined. The results showed that the formulated nanoparticles demonstrated attractive physicochemical properties, low cytotoxicity, potent antibacterial efficacy, and slow degradation and gradual CHX release profiles. Nanoparticles delivered efficiently inside dentinal-tubules structure to sufficient depth (>10μm) against the simulated upward pulpal hydrostatic-pressure, even after bonding-resins infiltration and were attached/retained on collagen-fibrils. These results verified the potential significance of this newly introduced drug-delivery therapeutic strategy for future clinical applications and promote for a new era of future dental research. This innovative drug-delivery strategy has proven to be a reliable method for delivering treatments that could be elaborated for other clinical applications in adhesive and restorative dentistry. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Spectroscopic investigation on structure and pH dependent Cocrystal formation between gamma-aminobutyric acid and benzoic acid.

PubMed

Du, Yong; Xue, Jiadan; Cai, Qiang; Zhang, Qi

2018-02-15

Vibrational spectroscopic methods, including terahertz absorption and Raman scattering spectroscopy, were utilized for the characterization and analysis of gamma-aminobutyric acid (GABA), benzoic acid (BA), and the corresponding GABA-BA cocrystal formation under various pH values of aqueous solution. Vibrational spectroscopic results demonstrated that the solvent GABA-BA cocrystal, similar as grinding counterpart, possessed unique characteristic features compared with that of starting parent compounds. The change of vibrational modes for GABA-BA cocrystal comparing with starting components indicates there is strong inter-molecular interaction between GABA and BA molecules during its cocrystallization process. Formation of GABA-BA cocrystal under slow solvent evaporation is impacted by the pH value of aqueous solution. Vibrational spectra indicate that the GABA-BA cocrystal could be stably formed with the solvent condition of 2.00≤pH≤7.00. In contrast, such cocrystallization did not occur and the cocrystal would dissociate into its parent components when the pH value of solvent is lower than 2.00. This study provides experimental benchmark to discriminate and identify the structure of cocrystal and also pH-dependent cocrystallization effect with vibrational spectroscopic techniques in solid-state pharmaceutical fields. Copyright © 2017 Elsevier B.V. All rights reserved.

Growth, structural, spectroscopic, thermal, dielectric and optical study of cobalt sulphide-doped ADP crystals

NASA Astrophysics Data System (ADS)

Kochuparampil, A. P.; Joshi, J. H.; Joshi, M. J.

2017-09-01

As ammonium dihydrogen phosphate (ADP) is a popular nonlinear optical crystal, to engineer its linear and nonlinear optical properties, the chalcogenide compound cobalt sulphide (CoS) was doped and the crystals were grown by the slow solvent evaporation method. To increase the solubility of CoS in water, its nanoparticles were synthesized by wet chemical technique using ethylene diamine as the capping agent followed by microwave irradiation. The nanoparticle sample exhibited finite solubility in water and was used to dope in ADP crystals. The powder XRD patterns showed the single phase nature of the doped crystals. The FTIR spectra confirmed the presence of various functional groups and EDAX gave the estimation of Co and S elements. The EPR spectroscopy also confirmed the presence of cobalt in the doped samples. TGA indicated slightly less thermal stability of the doped crystals compared to the pure ADP. The dielectric study was carried out at room temperature in the frequency range from 100Hz to 1MHz. Also, various linear optical parameters were evaluated for pure and doped crystals using UV-Vis spectroscopy. The second harmonic generation (SHG) efficiency of Nd:YAG laser was evaluated by the Kurtz and Parry method for the doped samples, it was found to be slightly lesser than that of the pure ADP crystals.

Experimental and computational approaches of a novel methyl (2E)-2-{[N-(2-formylphenyl)(4-methylbenzene)sulfonamido]methyl}-3-(4-chlorophenyl)prop-2-enoate: A potential antimicrobial agent and an inhibition of penicillin-binding protein

NASA Astrophysics Data System (ADS)

Murugavel, S.; Vetri velan, V.; Kannan, Damodharan; Bakthadoss, Manickam

2016-07-01

The title compound methyl(2E)-2-{[N-(2-formylphenyl) (4-methylbenzene)sulfonamido]methyl}-3-(4-chlorophenyl) prop-2-enoate (MFMSC) has been synthesized and single crystals were grown by slow evaporation solution growth technique at room temperature. Structural and vibrational spectroscopic studies were carried out by using single crystal X-ray diffraction, FT-IR and NMR spectral analysis together with DFT method using GAUSSIAN'03 software. The detailed interpretation of the vibrational spectra has been carried out by VEDA program. NBO analysis, Mulliken charge analysis, HOMO-LUMO, MEP, Global chemical reactivity descriptors and thermodynamic properties have been analyzed. The hyperpolarisability calculation reveals the present material has a reasonably good propensity for nonlinear optical activity. The obtained antimicrobial activity results indicate that the compound shows good to moderate activity against all tested bacterial and fungal pathogens. A computational study was also carried out to predict the drug-likeness and ADMET properties of the title compound. Due to the different potential biological activity of the title compound, molecular docking study is also reported and the compound might exhibit inhibitory activity against penicillin-binding protein PBP-2X.

Structural, vibrational, DFT and optical studies of a new non-centrosymmetric hybrid material (C4H12N2)[CoBr4

NASA Astrophysics Data System (ADS)

Tllili, Hafsia; Walha, Sandra; Elleuch, Slim; Fares Ali, Basem; Naïli, Houcine

2018-01-01

The crystals of the new organic-inorganic material (C4H12N2)[CoBr4] were grown by slow evaporation technique in aqueous solution and characterized by X-ray diffraction, infrared absorption, Raman spectroscopy scattering and thermal analysis. It crystallizes at room temperature in the non-centrosymmetric space group P212121. The structure is built from isolated [CoBr4]2- anions and piperazinediium (C4H12N2)2+ cations which are connected by a network of Nsbnd H⋯Br hydrogen bonds. Theoretical calculations were performed using density functional theory with the B3LYP/LanL2DZ level for studying the molecular structure and vibrational spectra of the title compound. TDDFT calculations at the same level of theory was undertaken to investigate the electronic properties. Good adhesion is observed between calculated and experimental results. The optical study reveals that the title compound undergoes three optical absorption bands at 641, 666 and 698 nm, respectively with an energy gap estimated to 2.23 eV. Based upon this value and the non-centrosymetric character of the structure, the title compound may show several interesting applications in the field of optoelectronics.

Vibrational spectroscopic study, charge transfer interaction and nonlinear optical properties of L-asparaginium picrate: a density functional theoretical approach.

PubMed

Elleuch, Nabil; Amamou, Walid; Ben Ahmed, Ali; Abid, Younes; Feki, Habib

2014-07-15

Single crystals of L-asparaginium picrate (LASP) were grown by slow evaporation technique at room temperature and were the subject of an X-ray powder diffraction study to confirm the crystalline nature of the synthesized compound. FT-IR and Raman spectra were recorded and analyzed with the aid of the density functional theory (DFT) calculations in order to make a suitable assignment of the observed bands. The optimum molecular geometry, normal mode wavenumbers, infrared and Raman intensities and the first hyperpolarizability were investigated with the help of B3LYP method using 6-31G(d) basis set. The theoretical FT-IR and Raman spectra of LASP were simulated and compared with the experimental data. A good agreement was shown and a reliable vibrational assignment was made. Natural bond orbital (NBO) analysis was carried out to demonstrate the various inter and intramolecular interactions that are responsible for the stabilization of the title compound leading to high NLO activity. A study on the electronic properties was performed by time-dependent DFT (TD-DFT) approach. The lowering in the HOMO and LUMO energy gap explains the eventual charge transfer interactions that take place within the molecules. Copyright © 2014 Elsevier B.V. All rights reserved.

Growth and characterization of Bis(L-threonine) copper (II) monohydrate single crystals: A semiorganic second order nonlinear optical material

NASA Astrophysics Data System (ADS)

Subhashini, R.; Sathya, D.; Sivashankar, V.; Latha Mageshwari, P. S.; Arjunan, S.

2016-12-01

Highly transparent solitary nonlinear semiorganic optical material Bis(L-threonine) copper (II) monohydrate [BLTCM], was synthesized by a conventional slow evaporation solution growth technique. The grown crystals were subjected to structural, optical, electrical, thermal, mechanical, SHG and Laser damage threshold studies. Single crystal XRD shows that the material crystallizes in monoclinic system with noncentrosymmetric space group P21. FT-IR and FT-RAMAN analyses confirm the various functional groups present in the grown crystal. The transparency range of BLTCM was determined by UV-vis-NIR studies and various optical constants such as extinction coefficient (K), refractive index, optical conductivity and electric susceptibility with real and imaginary parts of dielectric constant were calculated using the transmittance data which have applications in optoelectronic devices. Dielectric studies of the crystal were carried out at different frequencies and temperatures to analyze the electrical properties. TGA and DSC analyses were performed to study the thermal behaviour of the sample. The hardness stability of the grown specimen was investigated by Vickers microhardness test. The output intensity of second harmonic generation was confirmed using the Kurtz and Perry powder method. The laser induced surface damage threshold of the crystal was measured using Nd:YAG laser.

Growth of 4-(dimethylamino) benzaldehyde doped triglycine sulphate single crystals and its characterization

NASA Astrophysics Data System (ADS)

Rai, Chitharanjan; Sreenivas, K.; Dharmaprakash, S. M.

2009-11-01

Single crystals of triglycine sulphate (TGS) doped with 1 mol% of 4-(dimethylamino) benzaldehyde (DB) have been grown from aqueous solution at ambient temperature by slow evaporation technique. The effect of dopant on the crystal growth and dielectric, pyroelectric and mechanical properties of TGS crystal have been investigated. X-ray powder diffraction pattern for pure and doped TGS was collected to determine the lattice parameters. FTIR spectra were employed to confirm the presence of 4-(dimethylamino) benzaldehyde in TGS crystal, qualitatively. The dielectric permittivity has been studied as a function of temperature by cooling the sample at a rate of 1 °C/min. An increase in the Curie temperature Tc=51 °C (for pure TGS, Tc=48.5 °C) and decrease in maximum permittivity has been observed for doped TGS when compared to pure TGS crystal. Pyroelectric studies on doped TGS were carried out to determine pyroelectric coefficient. The Vickers's hardness of the doped TGS crystals along (0 1 0) face is higher than that of pure TGS crystal for the same face. Domain patterns on b-cut plates were observed using scanning electron microscope. The low dielectric constant, higher pyroelectric coefficient and higher value of hardness suggest that doped TGS crystals could be a potential material for IR detectors.

Variably-saturated groundwater modeling for optimizing managed aquifer recharge using trench infiltration

USGS Publications Warehouse

Heilweil, Victor M.; Benoit, Jerome; Healy, Richard W.

2015-01-01

Spreading-basin methods have resulted in more than 130 million cubic meters of recharge to the unconfined Navajo Sandstone of southern Utah in the past decade, but infiltration rates have slowed in recent years because of reduced hydraulic gradients and clogging. Trench infiltration is a promising alternative technique for increasing recharge and minimizing evaporation. This paper uses a variably saturated flow model to further investigate the relative importance of the following variables on rates of trench infiltration to unconfined aquifers: saturated hydraulic conductivity, trench spacing and dimensions, initial water-table depth, alternate wet/dry periods, and number of parallel trenches. Modeling results showed (1) increased infiltration with higher hydraulic conductivity, deeper initial water tables, and larger spacing between parallel trenches, (2) deeper or wider trenches do not substantially increase infiltration, (3) alternating wet/dry periods result in less overall infiltration than keeping the trenches continuously full, and (4) larger numbers of parallel trenches within a fixed area increases infiltration but with a diminishing effect as trench spacing becomes tighter. An empirical equation for estimating expected trench infiltration rates as a function of hydraulic conductivity and initial water-table depth was derived and can be used for evaluating feasibility of trench infiltration in other hydrogeologic settings

Growth and characterizaion of urea p-nitrophenol crystal: an organic nonlinear optical material for optoelectronic device application

NASA Astrophysics Data System (ADS)

Suresh, A.; Manikandan, N.; Jauhar, RO. MU.; Murugakoothan, P.; Vinitha, G.

2018-06-01

Urea p-nitrophenol, an organic nonlinear optical crystal was synthesized and grown adopting slow evaporation and seed rotation method. Single crystal X-ray diffraction study confirmed the formation of the desired crystal. High resolution X-ray diffraction study showed the defect nature of the crystal. The presence of functional groups in the material was confirmed by FTIR analysis. UV-Vis-NIR study indicates that the grown crystal has a wider transparency region with the lower cutoff wavelength at 423 nm. The grown crystal is thermally stable up to 120 °C as assessed by TG-DTA analysis. The optical homogeneity of the grown crystal was confirmed by birefringence study. The 1064 nm Nd-YAG laser was used to obtain laser induced surface damage threshold which was found to be 0.38, 0.25 and 0.33 GW/cm2 for (0 1 0), (1 1 - 1) and (0 1 1) planes, respectively. The dielectric study was performed to find the charge distribution inside the crystal. The hardness property of the titular material has been found using Vicker's microhardness study. The optical nonlinearity obtained from third order nonlinear optical measurements carried out using Z-scan technique showed that these samples could be exploited for optical limiting studies.

Growth and characterization of Melaminium bis (trichloroacetate) dihydrate

NASA Astrophysics Data System (ADS)

Kanagathara, N.; Renganathan, N. G.; Marchewka, M. K.; Sivakumar, N.; Gayathri, K.; Krishnan, P.; Gunasekaran, S.; Anbalagan, G.

2013-01-01

Single crystals of melaminium bis (trichloroacetate) dihydrate have been grown successfully by slow evaporation solution growth technique at room temperature. Single crystal X-ray diffraction analysis reveals that the compound crystallizes in monoclinic system with non -centrosymmetric space group C2 with lattice parameters a = 17.70 Å, b = 8.44 Å, c = 6.09 Å, α = 90°, β = 100.24°, γ = 90° and V = 900 (Å)3. The UV-Vis transmittance spectrum shows that the crystal has a good optical transmittance in the entire visible region with lower cutoff wavelength of 351 nm. The vibrational frequencies of various functional groups present in the crystal have been derived from FI-IR, FT-Raman and Confocal Raman analyses. The chemical structure of the compound was established by 1H and 13C NMR spectrum. TGA-DTA analysis reveals that the materials have good thermal stability and the melting point of the crystal is found to be 195 °C. The dielectric response of the crystals was studied in the frequency range 50 Hz to 5 MHz at different temperatures and the results are discussed. Etching studies show the growth pattern of the crystals. The second harmonic generation efficiency was measured in comparison with KDP by employing powder Kurtz method.

Seasonal, synoptic and diurnal variation of atmospheric water-isotopologues in the boundary layer of Southwestern Germany caused by plant transpiration, cold-front passages and dewfall.

NASA Astrophysics Data System (ADS)

Christner, Emanuel; Dyroff, Christoph; Kohler, Martin; Zahn, Andreas; Gonzales, Yenny; Schneider, Matthias

2013-04-01

Atmospheric water is an enormously crucial trace gas. It is responsible for ~70 % of the natural greenhouse effect (Schmidt et al., JGR, 2010) and carries huge amounts of latent heat. The isotopic composition of water vapor is an elegant tracer for a better understanding and quantification of the extremely complex and variable hydrological cycle in Earth's atmosphere (evaporation, cloud condensation, rainout, re-evaporation, snow), which in turn is a prerequisite to improve climate modeling and predictions. As H216O, H218O and HDO differ in vapor pressure and mass, isotope fractionation occurs due to condensation, evaporation and diffusion processes. In contrast to that, plants are able to transpire water with almost no isotope fractionation. For that reason the ratio of isotopologue concentrations in the boundary layer (BL) provides, compared to humidity measurements alone, independent and additional constraints for quantifying the strength of evaporation and transpiration. Furthermore the isotope ratios contain information about transport history of an air mass and microphysical processes, that is not accessible by humidity measurements. Within the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water) a commercial Picarro Analyzer L2120-i is operated at Karlsruhe in Southwestern Germany, which is continuously measuring the isotopologues H216O, HDO and H218O of atmospheric water vapor since January 2012. A one year record of H216O, HDO and H218O shows clear seasonal, synoptic and diurnal characteristics and reveals the main driving processes affecting the isotopic composition of water vapor in the Middle European BL. Changes in continental plant transpiration and evaporation throughout the year lead to a slow seasonal HDO/H216O-variation, that cannot be explained by pure Rayleigh condensation. Furthermore, cold-front passages from NW lead to fast and pronounced depletion of the HDO/H216O-ratio within minutes. Superimposed to these variations are local diurnal processes like dewfall, which cause a diurnal pattern captured by the deuterium excess.

Modeling of turbulence effects on the heat and mass transfer of evaporating sprays

NASA Astrophysics Data System (ADS)

Madhanabharatam, Balasubramanyam

A large diversity of two-phase gas-liquid flows of both scientific and practical interest involves the evaporation of near spherical liquid droplets in high temperature turbulent environments. Current numerical modeling approaches are predominantly focused towards the effects of continuous phase (gas phase) turbulence on the evaporation rates of liquid fuel sprays during the evaporation process, failing to account for the inherent turbulence present in the dispersed phase (liquid phase), due to the injection of sprays at high velocities. Existing models accounting for internal turbulence effects use Direct Numerical Simulations and Large Eddy Simulations that are computationally intensive. This research provides an alternative phenomenological approach of modeling droplet internal turbulence effects through the mass and heat transfer between the droplet surface and the external gas phase within a thin film inside the droplet. This finite conductivity (F-C) model was based on the two-temperature film theory, where the turbulence characteristics of the droplet are used to estimate the effective thermal diffusivity (alphaeff) within the droplet phase. The alphaeff is estimated from the physical properties of the flow within the droplet rather than from a 'curve-fit' as done conventionally. The results of the one-way coupled study indicated that the equilibrium drop temperature predictions were higher than calculations by the infinite conductivity (I-C) model. The liquid internal turbulence has a considerable effect on the diffusivity in the primary atomization regime. The thermal boundary layer was found to be substantially thick initially, decreasing quickly to a small value, exhibiting a reasonable physical trend. The two-way coupled studies (CFD) indicated that the F-C model, slowed down the evaporation process, produced larger droplets and longer tip penetration lengths during the initial stages of injection. For a jet in a supersonic cross-flow, results indicated that jet penetration increased rapidly in the vicinity of the injector exit and then gradually increased due to increase in the drag of the air stream. A modified drag coefficient was incorporated to improve model accuracy in predictions. Overall the results obtained from the numerical calculations during this study were reasonably comparable to measured data and showed more accurate comparisons to that of the I-C model.

MgO buffer layers on rolled nickel or copper as superconductor substrates

DOEpatents

Paranthaman, Mariappan; Goyal, Amit; Kroeger, Donald M.; List, III, Frederic A.

2001-01-01

Buffer layer architectures are epitaxially deposited on biaxially-textured rolled-Ni and/or Cu substrates for high current conductors, and more particularly buffer layer architectures such as MgO/Ag/Pt/Ni, MgO/Ag/Pd/Ni, MgO/Ag/Ni, MgO/Ag/Pd/Cu, MgO/Ag/Pt/Cu, and MgO/Ag/Cu. Techniques used to deposit these buffer layers include electron beam evaporation, thermal evaporation, rf magnetron sputtering, pulsed laser deposition, metal-organic chemical vapor deposition (MOCVD), combustion CVD, and spray pyrolysis.

Method for making MgO buffer layers on rolled nickel or copper as superconductor substrates

DOEpatents

Paranthaman, Mariappan; Goyal, Amit; Kroeger, Donald M.; List, III, Frederic A.

2002-01-01

Buffer layer architectures are epitaxially deposited on biaxially-textured rolled-Ni and/or Cu substrates for high current conductors, and more particularly buffer layer architectures such as MgO/Ag/Pt/Ni, MgO/Ag/Pd/Ni, MgO/Ag/Ni, MgO/Ag/Pd/Cu, MgO/Ag/Pt/Cu, and MgO/Ag/Cu. Techniques used to deposit these buffer layers include electron beam evaporation, thermal evaporation, rf magnetron sputtering, pulsed laser deposition, metal-organic chemical vapor deposition (MOCVD), combustion CVD, and spray pyrolysis.

Synthesis of a Glibenclamide Cocrystal: Full Spectroscopic and Thermal Characterization.

PubMed

Silva Filho, Silvério Ferreira; Pereira, Andreia Cardoso; Sarraguça, Jorge M G; Sarraguça, Mafalda C; Lopes, João; Façanha Filho, Pedro de Freitas; Dos Santos, Adenilson Oliveira; da Silva Ribeiro, Paulo Roberto

2018-06-01

A cocrystal of glibenclamide, an antidiabetic drug classified as type II compound according to the Biopharmaceutics Classification System, has been synthesized using tromethamine as coformer in 1:1 molar ratio, by slow solvent evaporation cocrystalization. The cocrystal obtained was characterized by X-ray powder diffraction, differential scanning calorimetry, Raman, mid infrared, and near-infrared spectroscopy. The results consistently show the formation of a cocrystal between active pharmaceutical ingredients and conformer with the synthons corresponding to hydrogen bonding between hydrogen in amines of tromethamine and carbonyl and sulfonyl groups in glibenclamide. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

A new Pu(iii) coordination geometry in (C5H5NBr)2[PuCl3(H2O)5]·2Cl·2H2O as obtained via supramolecular assembly in aqueous, high chloride media.

PubMed

Surbella, Robert G; Ducati, Lucas C; Pellegrini, Kristi L; McNamara, Bruce K; Autschbach, Jochen; Schwantes, Jon M; Cahill, Christopher L

2017-09-28

Crystals of a hydrated Pu(iii) chloride, (C 5 H 5 NBr) 2 [PuCl 3 (H 2 O) 5 ]·2Cl·2H 2 O, were grown via slow evaporation from acidic aqueous, high chloride media. X-ray diffraction data reveals the neutral [PuCl 3 (H 2 O) 5 ] tecton is assembled via charge assisted hydrogen and halogen bonds donated by 4-bromopyridinium cations and a series of inter-tecton hydrogen bonds.

Slow Release Of Reagent Chemicals From Gel Matrices

NASA Technical Reports Server (NTRS)

Debnam, William J.; Barber, Patrick G.; Coleman, James

1988-01-01

Procedure developed for slow release of reagent chemicals into solutions. Simple and inexpensive and not subject to failure of equipment. Use of toothpaste-type tube or pump dispenser conceivably provides more controlled technique for storage and dispensation of gel matrix. Possible uses include controlled, slow release of reagents in chemical reactions, crystal growth, space-flight experiments, and preformed gel medications from packets.

Cryotop vitrification as compared to conventional slow freezing for human embryos at the cleavage stage: survival and outcomes.

PubMed

Lin, Tseng-Kai; Su, Jin-Tsung; Lee, Fa-Kung; Lin, Yu-Ru; Lo, Hsiao-Ching

2010-09-01

This study was conducted to compare the efficacy of cryotop vitrification of human cleavage-stage embryos to that of conventional slow freezing of these embryos with respect to survival. A second objective was to compare the two cryopreservation techniques with respect to outcomes for a cohort of women. Cleavage-stage embryos from 102 patients were cryopreserved either by vitrification (57 patients) or by traditional slow freezing (45 patients). After thawing, rates of embryo survival, implantation, and clinical pregnancy were determined. Survival of embryos was significantly higher with the vitrification procedure as compared to traditional slow freezing [287/298 (96.3%) vs. 294/446 (65.9%); p < 0.05). Rates of implantation and clinical pregnancy were also significantly higher using vitrification procedure as compared to the slow freezing procedure (24.3% vs. 7.1% and 35.6% vs. 15.6% respectively, p < 0.05). As compared to conventional slow freezing, cryopreservation of human cleavage-stage embryo using vitrification results in higher rates of embryo survival, implantation, and clinical pregnancy. Vitrification therefore represents the superior cryopreservation technique for cleavage-stage embryos. Copyright © 2010 Taiwan Association of Obstetric & Gynecology. Published by Elsevier B.V. All rights reserved.

Crystal growth and characterization of third order nonlinear optical piperazinium bis(4-hydroxybenzenesulphonate) (P4HBS) single crystal

NASA Astrophysics Data System (ADS)

Pichan, Karuppasamy; Muthu, Senthil Pandian; Perumalsamy, Ramasamy

2017-09-01

The organic single crystal of piperazinium bis(4-hydroxybenzenesulphonate) (P4HBS) was grown by slow evaporation solution technique (SEST) at room temperature. The lattice parameters of the grown crystal were confirmed by single crystal X-ray diffraction analysis. Functional groups of P4HBS crystal were confirmed by FTIR spectrum analysis. The optical quality of the grown crystal was identified by the UV-Vis NIR spectrum analysis. The grown crystal has good optical transmittance in the range of 410-1100 nm. In photoluminescence spectrum, sharp emission peaks are observed, which indicates the ultraviolet (UV) emission. The photoconductivity study reveals that the grown crystal has negative photoconductive nature. The thermal behaviour of the P4HBS crystal was investigated by thermogravimetric and differential thermal analysis (TG-DTA). The mechanical stability of grown crystal was analyzed and the indentation size effect (ISE) was explained by Hays-Kendall's (HK) approach and proportional specimen resistance model (PSRM). Chemical etching study was carried out and the etch pit density (EPD) was calculated. The dielectric constant (ε‧) and dielectric loss (tan δ) as a function of frequency were measured for the grown crystal. The solid state parameters such as valence electron, plasma energy, Penn gap and Fermi energy were evaluated theoretically for the P4HBS using the empirical relation. The estimated values are used to calculate the electronic polarizability. The third-order nonlinear optical properties such as nonlinear refractive index (n2), absorption co-efficient (β) and susceptibility (χ(3)) were studied by Z-scan technique at 632.8 nm using He-Ne laser.

New supramolecular cocrystal of 2-amino-5-chloropyridine with 3-methylbenzoic acids: Syntheses, structural characterization, Hirshfeld surfaces and quantum chemical investigations

NASA Astrophysics Data System (ADS)

Thanigaimani, Kaliyaperumal; Khalib, Nuridayanti Che; Temel, Ersin; Arshad, Suhana; Razak, Ibrahim Abdul

2015-11-01

2-amino-5-chloropyridine: 3-methylbenzoic acid [(2A5CP) (3MBA)] (I) cocrystal was synthesized and its single crystal was grown by slow evaporation technique. The structure of the grown crystal was elucidated by using single crystal X-ray diffraction technique. The cocrystal belongs to the monoclinic crystallographic system with space group P21/c, Z = 4, and a = 13.3155 (5) Å, b = 5.5980 (2) Å, c = 18.3787 (7) Å, β = 110.045 (2)°. The crystal structure is stabilized by Npyridine-H•••Odbnd C, Cdbnd O-H•••Npyridine and C-H⋯O type hydrogen bonding interactions. The presence of unionized -COOH functional group in the cocrystal was identified both by spectral methods and X-ray structural analysis. The experimental studies obtained by using the methods of single crystal X-ray analysis, powder X-ray diffraction (PXRD) analysis, FTIR, 1H NMR and 13C NMR spectroscopies confirmed the predicted cocrystal. The supramolecular assembly of the cocrystal was analyzed and discussed. The molecular geometry, vibrational frequencies of the compound in the ground state were calculated by using the density functional theory (DFT) method with 6-311++G (d,p) basis set and were compared with the experimental data. Additionally, HOMO-LUMO energy gap, natural bond orbital (NBO) analysis and nonlinear optical (NLO) properties of the compound were performed at B3LYP/6-311++G (d,p) level. Hirshfeld surfaces were used to confirm the existence of inter-molecular interactions in the compound.

Transfiguring structural, optical and dielectric properties of cadmium thiourea acetate crystal by the addition of L-threonine for laser assisted device applications

NASA Astrophysics Data System (ADS)

Kulkarni, Rupali B.; Anis, Mohd; Hussaini, S. S.; Shirsat, Mahendra D.

2018-03-01

Present investigation reports the growth of pure and L-threonine (LT) doped cadmium thiourea acetate (CTA) crystals by slow solution evaporation technique followed by structural, optical and dielectric characterization studies. A bulk single crystal of LT-CTA has been grown at temperature 38 °C. The single crystal x-ray diffraction technique has been employed to confirm the structural parameters of pure and LT doped CTA crystals. The increase in optical transparency of LT-CTA crystal was ascertained in the range of 200 to 900 nm using UV-visible spectral analysis. The widened optical band gap of the LT-CTA crystal is found to be 4.7 eV. Pure and doped crystals are subjected to FT-IR analysis to indicate the presence of functional groups quantitatively. Appreciable enhancement in second harmonic generation (SHG) efficiency of LT-CTA crystal with reference to parent CTA was confirmed from Kurtz-Perry SHG test (1.31 times of CTA crystal). The assertive influence of LT on electrical properties of grown crystals has been investigated in the temperature range 35 °C-120 °C. Electronic purity and the color centered photoluminescence emission nature of pure and IA-CTA crystals were justified by luminescence analysis. With the aid of single beam Z-scan analysis, the Kerr lensing nonlinearity was identified and the magnitude of TONLO parameters has been determined. The cubic susceptibility (χ3) and figure of merit (FOM) was found to be 4.81 × 10-4esu and 978.35. Results vitalize LT-CTA for laser stabilization systems.

Synthesis and studies on structural, optical and nonlinear optical properties of novel organic inter-molecular compounds: 4-chloro-3-nitroaniline-3-hydroxy benzaldehyde and urea-4-dimethylaminopyridine

NASA Astrophysics Data System (ADS)

Pandey, Priyanka; Rai, R. N.

2018-05-01

Two novel organic inter-molecular compounds (IMCs), (3-(4-chloro-3-nitrophenylimino) methyl) phenol) (CNMP) and urea ̶ 4-dimethylaminopyridine complex (UDMAP), have been synthesized by solid state reaction. These two IMCs were identified by phase diagram study of CNA-HB and U-DMAP systems. The single crystals of newly obtained IMCs were grown by slow solvent evaporation technique at room temperature. Both the IMCs were further studied for their thermal, spectral, single crystal XRD for their atomic packing in molecule, crystallinity, optical and nonlinear optical behaviour. In both the cases, melting point of inter-molecular compounds was found to be higher than that of their parent components, CNMP was found to be thermally stable up to 158 °C while UDMAP was stable up to 144 °C, which indicate their extra stability than their parents. The single crystal XRD studies confirmed that CNMP has crystallized in orthorhombic unit cell with non-centrosymmetric space group P212121 while UDMAP has crystallized in monoclinic unit cell with centrosymmetric space group C2/c. The absorption spectrum of CNMP was found to be in between the absorption of parents, while broadening of peak and red shift was observed in UDMAP as compared to the parents. Second order nonlinear optical property of CNMP and UDMAP was studied using Kurtz Perry powder technique and intense green light emission was observed with CNMP on excitation with 1064 nm of Nd:YAG laser while no emission was observed with UDMAP.

A short term quality control tool for biodegradable microspheres.

PubMed

D'Souza, Susan; Faraj, Jabar A; Dorati, Rossella; DeLuca, Patrick P

2014-06-01

Accelerated in vitro release testing methodology has been developed as an indicator of product performance to be used as a discriminatory quality control (QC) technique for the release of clinical and commercial batches of biodegradable microspheres. While product performance of biodegradable microspheres can be verified by in vivo and/or in vitro experiments, such evaluation can be particularly challenging because of slow polymer degradation, resulting in extended study times, labor, and expense. Three batches of Leuprolide poly(lactic-co-glycolic acid) (PLGA) microspheres having varying morphology (process variants having different particle size and specific surface area) were manufactured by the solvent extraction/evaporation technique. Tests involving in vitro release, polymer degradation and hydration of the microspheres were performed on the three batches at 55°C. In vitro peptide release at 55°C was analyzed using a previously derived modification of the Weibull function termed the modified Weibull equation (MWE). Experimental observations and data analysis confirm excellent reproducibility studies within and between batches of the microsphere formulations demonstrating the predictability of the accelerated experiments at 55°C. The accelerated test method was also successfully able to distinguish the in vitro product performance between the three batches having varying morphology (process variants), indicating that it is a suitable QC tool to discriminate product or process variants in clinical or commercial batches of microspheres. Additionally, data analysis utilized the MWE to further quantify the differences obtained from the accelerated in vitro product performance test between process variants, thereby enhancing the discriminatory power of the accelerated methodology at 55°C.

Synthesis, crystal structure and growth of a new inorganic- organic hybrid compound for nonlinear optical applications: Aquadiiodo (3-aminopropanoic acid) cadmium (II)

NASA Astrophysics Data System (ADS)

Boopathi, K.; Babu, S. Moorthy; Jagan, R.; Ramasamy, P.

2017-12-01

The new inorganic-organic hybrid material aquadiiodo (3-aminopropanoic acid) cadmium (II) [ADI (3-AP) Cd] has been successfully synthesized and good quality crystals have been grown by slow evaporation solution technique. The structure was determined by single crystal X-ray diffraction at room temperature. The compound crystallizes in monoclinic crystal system with centro symmetric space group P21/c and four molecules in the unit cell. The structure of the title compound was further confirmed by 1H and 13C nuclear magnetic resonance spectral analysis. FT-IR spectroscopy was used to confirm the presence of various functional groups in the compound. The transmittance and optical parameters of the crystal were studied by UV- Visible-NIR spectroscopy. The thermal stability of the grown crystal was evaluated using thermogravimetric and differential thermal analyses. Mechanical hardness has been identified by Vickers micro hardness study and work hardening coefficient was calculated. Dielectric measurement was carried out as a function of frequency and results are discussed. The growth mechanism of the crystal was assessed by chemical etching studies. The third-order nonlinear optical susceptibility of [ADI (3-AP) Cd] was derived using the Z-scan technique, and it was 3.24955 × 10-8 esu. The positive nonlinear refractive index 2.48505 × 10-11 m2/W, is an indication of self-defocusing optical nonlinearity of the sample. It is believed that the [ADI (3-AP) Cd] is a promising new candidate for developing efficient nonlinear optical and optical power limiting devices.

Rapid Prototyping of Patterned Multifunctional Nanostructures

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

FAN,HONGYOU; LU,YUNFENG; LOPEZ,GABRIEL P.

2000-07-18

The ability to engineer ordered arrays of objects on multiple length scales has potential for applications such as microelectronics, sensors, wave guides, and photonic lattices with tunable band gaps. Since the invention of surfactant templated mesoporous sieves in 1992, great progress has been made in controlling different mesophases in the form of powders, particles, fibers, and films. To date, although there have been several reports of patterned mesostructures, materials prepared have been limited to metal oxides with no specific functionality. For many of the envisioned applications of hierarchical materials in micro-systems, sensors, waveguides, photonics, and electronics, it is necessary tomore » define both form and function on several length scales. In addition, the patterning strategies utilized so far require hours or even days for completion. Such slow processes are inherently difficult to implement in commercial environments. The authors present a series of new methods of producing patterns within seconds. Combining sol-gel chemistry, Evaporation-Induced Self-Assembly (EISA), and rapid prototyping techniques like pen lithography, ink-jet printing, and dip-coating on micro-contact printed substrates, they form hierarchically organized silica structures that exhibit order and function on multiple scales: on the molecular scale, functional organic moieties are positioned on pore surfaces, on the mesoscale, mono-sized pores are organized into 1-, 2-, or 3-dimensional networks, providing size-selective accessibility from the gas or liquid phase, and on the macroscale, 2-dimensional arrays and fluidic or photonic systems may be defined. These rapid patterning techniques establish for the first time a link between computer-aided design and rapid processing of self-assembled nanostructures.« less

Microscale Investigation of Thermo-Fluid Transport in the Transition FIL, Region of an Evaporating Capillary Meniscus Using a Microgravity Environment

NASA Technical Reports Server (NTRS)

Kihm, K. D.; Allen, J. S.; Hallinan, K. P.; Pratt, D. M.

2004-01-01

In order to enhance the fundamental understanding of thin film evaporation and thereby improve the critical design concept for two-phase heat transfer devices, microscale heat and mass transport is to be investigated for the transition film region using state-of-the-art optical diagnostic techniques. By utilizing a microgravity environment, the length scales of the transition film region can be extended sufficiently, from submicron to micron, to probe and measure the microscale transport fields which are affected by intermolecular forces. Extension of the thin film dimensions under microgravity will be achieved by using a conical evaporator made of a thin silicon substrate under which concentric and individually controlled micro-heaters are vapor-deposited to maintain either a constant surface temperature or a controlled temperature variation. Local heat transfer rates, required to maintain the desired wall temperature boundary condition, will be measured and recorded by the concentric thermoresistance heaters controlled by a Wheatstone bridge circuit, The proposed experiment employs a novel technique to maintain a constant liquid volume and liquid pressure in the capillary region of the evaporating meniscus so as to maintain quasi-stationary conditions during measurements on the transition film region. Alternating use of Fizeau interferometry via white and monochromatic light sources will measure the thin film slope and thickness variation, respectively. Molecular Fluorescence Tracking Velocimetry (MFTV), utilizing caged fluorophores of approximately 10-nm in size as seeding particles, will be used to measure the velocity profiles in the thin film region. An optical sectioning technique using confocal microscopy will allow submicron depthwise resolution for the velocity measurements within the film for thicknesses on the order of a few microns. Digital analysis of the fluorescence image-displacement PDFs, as described in the main proposal, can further enhance the depthwise resolution.

Evaporation of Binary Sessile Drops: Infrared and Acoustic Methods To Track Alcohol Concentration at the Interface and on the Surface.

PubMed

Chen, Pin; Toubal, Malika; Carlier, Julien; Harmand, Souad; Nongaillard, Bertrand; Bigerelle, Maxence

2016-09-27

Evaporation of droplets of three pure liquids (water, 1-butanol, and ethanol) and four binary solutions (5 wt % 1-butanol-water-based solution and 5, 25, and 50 wt % ethanol-water-based solutions) deposited on hydrophobic silicon was investigated. A drop shape analyzer was used to measure the contact angle, diameter, and volume of the droplets. An infrared camera was used for infrared thermal mapping of the droplet's surface. An acoustic high-frequency echography technique was, for the first time, applied to track the alcohol concentration in a binary-solution droplet. Evaporation of pure alcohol droplets was executed at different values of relative humidity (RH), among which the behavior of pure ethanol evaporation was notably influenced by the ambient humidity as a result of high hygrometry. Evaporation of droplets of water and binary solutions was performed at a temperature of 22 °C and a mean humidity of approximately 50%. The exhaustion times of alcohol in the droplets estimated by the acoustic method and the visual method were similar for the water-1-butanol mixture; however, the time estimated by the acoustic method was longer when compared with that estimated by the visual method for the water-ethanol mixture due to the residual ethanol at the bottom of the droplet.

Isotopic composition of atmospheric moisture from pan water evaporation measurements.

PubMed

Devi, Pooja; Jain, Ashok Kumar; Rao, M Someshwer; Kumar, Bhishm

2015-01-01

A continuous and reliable time series data of the stable isotopic composition of atmospheric moisture is an important requirement for the wider applicability of isotope mass balance methods in atmospheric and water balance studies. This requires routine sampling of atmospheric moisture by an appropriate technique and analysis of moisture for its isotopic composition. We have, therefore, used a much simpler method based on an isotope mass balance approach to derive the isotopic composition of atmospheric moisture using a class-A drying evaporation pan. We have carried out the study by collecting water samples from a class-A drying evaporation pan and also by collecting atmospheric moisture using the cryogenic trap method at the National Institute of Hydrology, Roorkee, India, during a pre-monsoon period. We compared the isotopic composition of atmospheric moisture obtained by using the class-A drying evaporation pan method with the cryogenic trap method. The results obtained from the evaporation pan water compare well with the cryogenic based method. Thus, the study establishes a cost-effective means of maintaining time series data of the isotopic composition of atmospheric moisture at meteorological observatories. The conclusions drawn in the present study are based on experiments conducted at Roorkee, India, and may be examined at other regions for its general applicability.

Observations of internal flow inside an evaporating nanofluid sessile droplet in the presence of an entrapped air bubble

PubMed Central

Shin, Dong Hwan; Allen, Jeffrey S.; Lee, Seong Hyuk; Choi, Chang Kyoung

2016-01-01

Using a unique, near-field microscopy technique, fringe patterns and nanoparticle motions are visualized immediately following a nanofluid droplet deposition on a glass substrate in which an air bubble is entrapped. The nanofluid consists of DI-water, 0.10% Aluminum Oxide nanoparticles with an average diameter of 50 nm, and 0.0005% yellow-green polystyrene fluorescent particles of 1 μm diameter. High-speed, fluorescent-mode confocal imaging enables investigation of depth-wise sectioned particle movements in the nanofluid droplet inside which a bubble is entrapped. The static contact angle is increased when a bubble is applied. In the presence of the bubble in the droplet, the observed flow toward the center of the droplet is opposite to the flow observed in a droplet without the bubble. When the bubble is present, the evaporation process is retarded. Also, random motion is observed in the contact line region instead of the typical evaporation-driven flow toward the droplet edge. Once the bubble bursts, however, the total evaporation time decreases due to the change in the contact line characteristics. Moreover, the area of fringe patterns beneath the bubble increases with time. Discussed herein is a unique internal flow that has not been observed in nanofluid droplet evaporation. PMID:27615999

Observations of internal flow inside an evaporating nanofluid sessile droplet in the presence of an entrapped air bubble.

PubMed

Shin, Dong Hwan; Allen, Jeffrey S; Lee, Seong Hyuk; Choi, Chang Kyoung

2016-09-12

Using a unique, near-field microscopy technique, fringe patterns and nanoparticle motions are visualized immediately following a nanofluid droplet deposition on a glass substrate in which an air bubble is entrapped. The nanofluid consists of DI-water, 0.10% Aluminum Oxide nanoparticles with an average diameter of 50 nm, and 0.0005% yellow-green polystyrene fluorescent particles of 1 μm diameter. High-speed, fluorescent-mode confocal imaging enables investigation of depth-wise sectioned particle movements in the nanofluid droplet inside which a bubble is entrapped. The static contact angle is increased when a bubble is applied. In the presence of the bubble in the droplet, the observed flow toward the center of the droplet is opposite to the flow observed in a droplet without the bubble. When the bubble is present, the evaporation process is retarded. Also, random motion is observed in the contact line region instead of the typical evaporation-driven flow toward the droplet edge. Once the bubble bursts, however, the total evaporation time decreases due to the change in the contact line characteristics. Moreover, the area of fringe patterns beneath the bubble increases with time. Discussed herein is a unique internal flow that has not been observed in nanofluid droplet evaporation.

Effect of annealing and In content on the properties of electron beam evaporated ZnO films

NASA Astrophysics Data System (ADS)

Mohamed, S. H.; Ali, H. M.; Mohamed, H. A.; Salem, A. M.

2005-08-01

The effect of both annealing and In content on the properties of ZnO films prepared by electron beam evaporation were investigated. The evaporation was carried out at room temperature from bulk samples prepared by sintering technique. X-ray diffraction showed that the structure of ZnO-In{2}O{3} films depends on both the In content and annealing temperature. Amorphous, highly transparent and relatively low resistive films which can be suitable for the usage as transparent electrode of organic light-emitting diode were obtained upon annealing at 300 circC. Partially crystalline, highly transparent and highly resistive films which can be used in piezoelectric applications were obtained upon annealing at 500 circC. For each composition the refractive index has no monotonic variation upon increasing annealing temperature.

Investigation of an inverted meniscus heat pipe wick concept

NASA Technical Reports Server (NTRS)

Saaski, E. W.

1975-01-01

A wicking concept is described for efficient evaporation of heat pipe working fluids under diverse conditions. It embodies the high heat transfer coefficient of the circumferential groove while retaining the circumferential fluid transport capability of a thick porous wick or screen. Experimental tests are described which substantiate the efficacy of the evaporation technique for a circumferentially-grooved heat pipe charged alternately with ammonia and R-ll (CCl3F). With ammonia, heat transfer coefficients in the range of 2 to 2.7 W/sq cm K were measured at heat flux densities up to 20 W/sq cm while, with R-ll, a heat transfer coefficient of l.0 W/sq cm K was measured with flux densities up to 5 W/sq cm. Heat transfer coefficients and flux densities were unusually high compared to literature data for other nonboiling evaporative surfaces.

Megathrust Earthquake Swarms Contemporaneous to Slow Slip and Non-Volcanic Tremor in Southern Mexico, Detected and Analyzed through a Template Matching Approach

NASA Astrophysics Data System (ADS)

Holtkamp, S.; Brudzinski, M. R.; Cabral-Cano, E.; Arciniega-Ceballos, A.

2012-12-01

An outstanding question in geophysics is the degree to which the newly discovered types of slow fault slip are related to their destructive cousin - the earthquake. Here, we utilize a local network along the Oaxacan segment of the Middle American subduction zone to investigate the potential relationship between slow slip, non-volcanic tremor (NVT), and earthquakes along the subduction megathrust. We have developed a multi-station "template matching" waveform cross correlation technique which is able to detect and locate events several orders of magnitude smaller than would be possible using more traditional techniques. Also, our template matching procedure is capable of consistently locate events which occur during periods of increased background activity (e.g., during productive NVT, loud cultural noise, or after larger earthquakes) because the multi-station detector is finely tuned to events with similar hypocentral location and focal mechanism. The local network in the Oaxaca region allows us to focus on documented megathrust earthquake swarms, which we focus on because slow slip is hypothesized to be the cause for earthquake swarms in some tectonic environments. We identify a productive earthquake swarm in July 2006 (~600 similar earthquakes detected), which occurred during a week-long episode of productive tremor and slow slip. Families of events in this sequence were also active during larger and longer slow slip events, which provides a potential link between slow slip in the transition zone and earthquakes at the downdip end of the seismogenic portion of the megathrust. Because template matching techniques only detect similar signals, detected waveforms can be stacked together to produce higher signal to noise ratios or cross correlated against each other to produce precise relative phase arrival times. We are using the refined signals to look for evidence of expansion or propagation of hypocenters during these earthquake swarms, which could be used as a test for determining their underlying processes (e.g., fluid diffusion or slow slip).

Evaporation rate of water in hydrophobic confinement.

PubMed

Sharma, Sumit; Debenedetti, Pablo G

2012-03-20

The drying of hydrophobic cavities is believed to play an important role in biophysical phenomena such as the folding of globular proteins, the opening and closing of ligand-gated ion channels, and ligand binding to hydrophobic pockets. We use forward flux sampling, a molecular simulation technique, to compute the rate of capillary evaporation of water confined between two hydrophobic surfaces separated by nanoscopic gaps, as a function of gap, surface size, and temperature. Over the range of conditions investigated (gaps between 9 and 14 Å and surface areas between 1 and 9 nm(2)), the free energy barrier to evaporation scales linearly with the gap between hydrophobic surfaces, suggesting that line tension makes the predominant contribution to the free energy barrier. The exponential dependence of the evaporation rate on the gap between confining surfaces causes a 10 order-of-magnitude decrease in the rate when the gap increases from 9 to 14 Å. The computed free energy barriers are of the order of 50 kT and are predominantly enthalpic. Evaporation rates per unit area are found to be two orders of magnitude faster in confinement by the larger (9 nm(2)) than by the smaller (1 nm(2)) surfaces considered here, at otherwise identical conditions. We show that this rate enhancement is a consequence of the dependence of hydrophobic hydration on the size of solvated objects. For sufficiently large surfaces, the critical nucleus for the evaporation process is a gap-spanning vapor tube.

The Effect of Evaporated Salt Solutions on the Optical Dating Properties of JSC Mars-1: "Seasoning" for a Mars Soil Simulant

NASA Astrophysics Data System (ADS)

Lepper, Kenneth

2009-08-01

Optically stimulated luminescence dating, or optical dating, is an established terrestrial geochronometric technique that is being adapted to date sedimentary deposits and landforms on the surface of Mars. Recent discoveries have highlighted the astrobiological significance and occurrence of halite on the surface of Mars. The objective of the experiments in this study was to create a simplistic analogue of the sedimentary material that would result from evaporation of ion-containing pore water out of martian regolith and evaluate the influence the evaporated salts would have on in situ optical dating of silicate sediments. The radiation dose response, as measured by infrared stimulated luminescence (IRSL), from evaporated mixtures of JSC Mars-1 and solutions of sodium chloride and calcium sulfate was documented. The results suggest that the presence of CaSO4 and NaCl within the aggregated particles does not have adverse effects on IRSL dose response and that aggregates of this type exhibit dose response characteristics that are appropriate for optical dating.

Survey of ion plating sources

NASA Technical Reports Server (NTRS)

Spalvins, T.

1979-01-01

Ion plating is a plasma deposition technique where ions of the gas and the evaporant have a decisive role in the formation of a coating in terms of adherence, coherence, and morphological growth. The range of materials that can be ion plated is predominantly determined by the selection of the evaporation source. Based on the type of evaporation source, gaseous media and mode of transport, the following will be discussed: resistance, electron beam sputtering, reactive and ion beam evaporation. Ionization efficiencies and ion energies in the glow discharge determine the percentage of atoms which are ionized under typical ion plating conditions. The plating flux consists of a small number of energetic ions and a large number of energetic neutrals. The energy distribution ranges from thermal energies up to a maximum energy of the discharge. The various reaction mechanisms which contribute to the exceptionally strong adherence - formation of a graded substrate/coating interface are not fully understood, however the controlling factors are evaluated. The influence of process variables on the nucleation and growth characteristics are illustrated in terms of morphological changes which affect the mechanical and tribological properties of the coating.

Numerical Analysis of the Heat Transfer Characteristics within an Evaporating Meniscus

NASA Astrophysics Data System (ADS)

Ball, Gregory

A numerical analysis was performed as to investigate the heat transfer characteristics of an evaporating thin-film meniscus. A mathematical model was used in the formulation of a third order ordinary differential equation. This equation governs the evaporating thin-film through use of continuity, momentum, energy equations and the Kelvin-Clapeyron model. This governing equation was treated as an initial value problem and was solved numerically using a Runge-Kutta technique. The numerical model uses varying thermophysical properties and boundary conditions such as channel width, applied superheat, accommodation coefficient and working fluid which can be tailored by the user. This work focused mainly on the effects of altering accommodation coefficient and applied superheat. A unified solution is also presented which models the meniscus to half channel width. The model was validated through comparison to literature values. In varying input values the following was determined; increasing superheat was found to shorten the film thickness and greatly increase the interfacial curvature overshoot values. The effect of decreasing accommodation coefficient lengthened the thin-film and retarded the evaporative effects.

Design and performance considerations of evaporative-pad, waste-heat greenhouses

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

Olszewski, M.

1978-01-01

Rising fuel costs and limited fuel availability have forced greenhouse operators to seek alternative means of heating their greenhouses in an effort to reduce production costs and conserve energy. One such alternative uses power plant reject heat, which is contained in the condenser cooling water, and a bank of evaporative pads to provide winter heating. The design technique used to size the evaporative pad system to meet both summer cooling and winter heating demands is described. Additionally, a computational scheme that simulates the system performance is presented. This analytical model is used to determine the greenhouse operating conditions that maintainmore » the vegetation in its thermal comfort zone. The evaporative pad model uses the Merkel total heat approximation and an experimentally derived transfer coefficient. Energy balance considerations on the vegetation provide a means of viewing optimal vegetation growth in terms of greenhouse environmental factors. In general, the results indicate that the vegetation can be maintained within its thermal comfort zone if sufficient warm water is available to the pads and the air stream flow is properly adjusted.« less

A sensitivity study of the effects of evaporation/condensation accommodation coefficients on transient heat pipe modeling

NASA Astrophysics Data System (ADS)

Hall, Michael L.; Doster, J. Michael

1990-03-01

The dynamic behavior of liquid metal heat pipe models is strongly influenced by the choice of evaporation and condensation modeling techniques. Classic kinetic theory descriptions of the evaporation and condensation processes are often inadequate for real situations; empirical accommodation coefficients are commonly utilized to reflect nonideal mass transfer rates. The complex geometries and flow fields found in proposed heat pipe systems cause considerable deviation from the classical models. the THROHPUT code, which has been described in previous works, was developed to model transient liquid metal heat pipe behavior from frozen startup conditions to steady state full power operation. It is used here to evaluate the sensitivity of transient liquid metal heat pipe models to the choice of evaporation and condensation accommodation coefficients. Comparisons are made with experimental liquid metal heat pipe data. It is found that heat pipe behavior can be predicted with the proper choice of the accommodation coefficients. However, the common assumption of spatially constant accommodation coefficients is found to be a limiting factor in the model.

Time-lagged autoencoders: Deep learning of slow collective variables for molecular kinetics

NASA Astrophysics Data System (ADS)

Wehmeyer, Christoph; Noé, Frank

2018-06-01

Inspired by the success of deep learning techniques in the physical and chemical sciences, we apply a modification of an autoencoder type deep neural network to the task of dimension reduction of molecular dynamics data. We can show that our time-lagged autoencoder reliably finds low-dimensional embeddings for high-dimensional feature spaces which capture the slow dynamics of the underlying stochastic processes—beyond the capabilities of linear dimension reduction techniques.

Evaporation process in histological tissue sections for neutron autoradiography.

PubMed

Espector, Natalia M; Portu, Agustina; Santa Cruz, Gustavo A; Saint Martin, Gisela

2018-05-01

The analysis of the distribution and density of nuclear tracks forming an autoradiography in a nuclear track detector (NTD) allows the determination of 10 B atoms concentration and location in tissue samples from Boron Neutron Capture Therapy (BNCT) protocols. This knowledge is of great importance for BNCT dosimetry and treatment planning. Tissue sections studied with this technique are obtained by cryosectioning frozen tissue specimens. After the slicing procedure, the tissue section is put on the NTD and the sample starts drying. The thickness varies from its original value allowing more particles to reach the detector and, as the mass of the sample decreases, the boron concentration in the sample increases. So in order to determine the concentration present in the hydrated tissue, the application of corrective coefficients is required. Evaporation mechanisms as well as various factors that could affect the process of mass variation are outlined in this work. Mass evolution for tissue samples coming from BDIX rats was registered with a semimicro analytical scale and measurements were analyzed with software developed to that end. Ambient conditions were simultaneously recorded, obtaining reproducible evaporation curves. Mathematical models found in the literature were applied for the first time to this type of samples and the best fit of the experimental data was determined. The correlation coefficients and the variability of the parameters were evaluated, pointing to Page's model as the one that best represented the evaporation curves. These studies will contribute to a more precise assessment of boron concentration in tissue samples by the Neutron Autoradiography technique.

Controlled evaporative self-assembly of confined microfluids: A route to complex ordered structures

NASA Astrophysics Data System (ADS)

Byun, Myunghwan

The evaporative self-assembly of nonvolatile solutes such as polymers, nanocrystals, and carbon nanotubes has been widely recognized as a non-lithographic means of producing a diverse range of intriguing complex structures. Due to the spatial variation of evaporative flux and possible convection, however, these non-equilibrium dissipative structures (e.g., fingering patterns and polygonal network structures) are often irregularly and stochastically organized. Yet for many applications in microelectronics, data storage devices, and biotechnology, it is highly desirable to achieve surface patterns having a well-controlled spatial arrangement. To date, only a few elegant studies have centered on precise control over the evaporation process to produce ordered structures. In a remarked comparison with conventional lithography techniques, surface patterning by controlled solvent evaporation is simple and cost-effective, offering a lithography- and external field-free means to organize nonvolatile materials into ordered microscopic structures over large surface areas. The ability to engineer an evaporative self-assembly process that yields a wide range of complex, self-organizing structures over large areas offers tremendous potential for applications in electronics, optoelectronics, and bio- or chemical sensors. We developed a facile, robust tool for evaporating polymer, nanoparticle, or DNA solutions in curve-on-flat geometries to create versatile, highly regular microstructures, including hierarchically structured polymer blend rings, conjugated polymer "snake-skins", block copolymer stripes, and punch-hole-like meshes, biomolecular microring arrays, etc. The mechanism of structure formation was elucidated both experimentally and theoretically. Our method further enhances current fabrication approaches to creating highly ordered structures in a simple and cost-effective manner, envisioning the potential to be tailored for use in photonics, optoelectronics, microfluidic devices, nanotechnology and biotechnology, etc.

Sympathetic Cooling of Lattice Atoms by a Bose-Einstein Condensate

DTIC Science & Technology

2010-08-13

average out to zero net change in momentum. This type of cooling is the basis for techniques such as Zeeman slowing and Magneto - optical traps . On a...change in momentum. This type of cooling is the basis for techniques such as Zeeman slowing and Magneto - optical traps . On a more basic level, an excited...cause stimulated emission of a second excitation. A quantitative explanation requires the use of the density fluctuation operator . This operator

DASCH ON KU Cyg: A {approx} 5 YEAR DUST ACCRETION EVENT IN {approx} 1900

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

Tang Sumin; Grindlay, Jonathan; Los, Edward

2011-09-01

KU Cyg is an eclipsing binary consisting of an F-type star accreting through a large accretion disk from a K5III red giant. Here we present the discovery of a 5 year dip around 1900 found from its 100 year DASCH light curve. It showed a {approx}0.5 mag slow fading from 1899 to 1903 and brightened back around 1904 on a relatively shorter timescale. The light curve shape of the 1899-1904 fading-brightening event differs from the dust production and dispersion process observed in R Coronae Borealis stars, which usually has a faster fading and slower recovery, and for KU Cyg ismore » probably related to the accretion disk surrounding the F star. The slow fading in KU Cyg is probably caused by increases in dust extinction in the disk, and the subsequent quick brightening may be due to the evaporation of dust transported inward through the disk. The extinction excess which caused the fading may arise from increased mass transfer rate in the system or from dust clump ejections from the K giant.« less

Study of the pyrolysis of sludge and sludge/disposal filter cake mix for the production of value added products.

PubMed

Velghe, Inge; Carleer, Robert; Yperman, Jan; Schreurs, Sonja

2013-04-01

Slow and fast pyrolysis of sludge and sludge/disposal filter cake (FC) mix are performed to investigate the liquid and solid products for their use as value added products. The obtained slow pyrolysis liquid products separate in an oil, a water rich fraction and a valuable crystalline solid 5,5-dimethyl hydantoin. During fast pyrolysis, mainly an oil fraction is formed. Aliphatic acids and amides present in the water rich fractions can be considered as value added products and could be purified. The oil fractions have properties which make them promising as fuel (25-35 MJ/kg, 14-20 wt% water content, 0.2-0.6 O/C value), but upgrading is necessary. Sludge/FC oils have a lower calorific value, due to evaporation of alcohols present in FC. ICP-AES analyses reveal that almost none of the metals present in sludge or sludge/FC are transferred towards the liquid fractions. The metals are enriched in the solid fractions. Copyright © 2013 Elsevier Ltd. All rights reserved.

Treatment of evaporator condensates by pervaporation

DOEpatents

Blume, Ingo; Baker, Richard W.

1990-01-01

A pervaporation process for separating organic contaminants from evaporator condensate streams is disclosed. The process employs a permselective membrane that is selectively permeable to an organic component of the condensate. The process involves contacting the feed side of the membrane with a liquid condensate stream, and withdrawing from the permeate side a vapor enriched in the organic component. The driving force for the process is the in vapor pressure across the membrane. This difference may be provided for instance by maintaining a vacuum on the permeate side, or by condensing the permeate. The process offers a simple, economic alternative to other separation techniques.

Magnetic resonance imaging of convection in laser-polarized xenon

NASA Technical Reports Server (NTRS)

Mair, R. W.; Tseng, C. H.; Wong, G. P.; Cory, D. G.; Walsworth, R. L.

2000-01-01

We demonstrate nuclear magnetic resonance (NMR) imaging of the flow and diffusion of laser-polarized xenon (129Xe) gas undergoing convection above evaporating laser-polarized liquid xenon. The large xenon NMR signal provided by the laser-polarization technique allows more rapid imaging than one can achieve with thermally polarized gas-liquid systems, permitting shorter time-scale events such as rapid gas flow and gas-liquid dynamics to be observed. Two-dimensional velocity-encoded imaging shows convective gas flow above the evaporating liquid xenon, and also permits the measurement of enhanced gas diffusion near regions of large velocity variation.

In situ calibration of the foil detector for an infrared imaging video bolometer using a carbon evaporation technique

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

Mukai, K., E-mail: mukai.kiyofumi@LHD.nifs.ac.jp; Peterson, B. J.; SOKENDAI

The InfraRed imaging Video Bolometer (IRVB) is a useful diagnostic for the multi-dimensional measurement of plasma radiation profiles. For the application of IRVB measurement to the neutron environment in fusion plasma devices such as the Large Helical Device (LHD), in situ calibration of the thermal characteristics of the foil detector is required. Laser irradiation tests of sample foils show that the reproducibility and uniformity of the carbon coating for the foil were improved using a vacuum evaporation method. Also, the principle of the in situ calibration system was justified.

Transition from stripe-like patterns to a particulate film using driven evaporating menisci.

PubMed

Noguera-Marín, Diego; Moraila-Martínez, Carmen L; Cabrerizo-Vílchez, Miguel A; Rodríguez-Valverde, Miguel A

2014-07-01

Better control of colloidal assembly by convective deposition is particularly helpful in particle templating. However, knowledge of the different factors that can alter colloidal patterning mechanisms is still insufficient. Deposit morphology is strongly ruled by contact line dynamics, but the wettability properties of the substrate can alter it drastically. In this work, we experimentally examined the roles of substrate contact angle hysteresis and receding contact angle using driven evaporating menisci similar to the dip-coating technique but at a low capillary number. We used smooth substrates with very different wettability properties and nanoparticles of different sizes. For fixed withdrawal velocity, evaporation conditions, and nanoparticle concentration, we analyzed the morphology of the deposits formed on each substrate. A gradual transition from stripe-like patterns to a film was observed as the contact angle hysteresis and receding contact angle were lowered.

Organic ferroelectric evaporator with substrate cooling and in situ transport capabilities.

PubMed

Foreman, K; Labedz, C; Shearer, M; Adenwalla, S

2014-04-01

We report on the design, operation, and performance of a thermal evaporation chamber capable of evaporating organic thin films. Organic thin films are employed in a diverse range of devices and can provide insight into fundamental physical phenomena. However, growing organic thin films is often challenging and requires very specific deposition parameters. The chamber presented here is capable of cooling sample substrates to temperatures below 130 K and allows for the detachment of the sample from the cooling stage and in situ transport. This permits the use of multiple deposition techniques in separate, but connected, deposition chambers without breaking vacuum and therefore provides clean, well characterized interfaces between the organic thin film and any adjoining layers. We also demonstrate a successful thin film deposition of an organic material with a demanding set of deposition parameters, showcasing the success of this design.

Flow visualization and characterization of evaporating liquid drops

NASA Technical Reports Server (NTRS)

Chao, David F. (Inventor); Zhang, Nengli (Inventor)

2004-01-01

An optical system, consisting of drop-reflection image, reflection-refracted shadowgraphy and top-view photography, is used to measure the spreading and instant dynamic contact angle of a volatile-liquid drop on a non-transparent substrate. The drop-reflection image and the shadowgraphy is shown by projecting the images of a collimated laser beam partially reflected by the drop and partially passing through the drop onto a screen while the top view photograph is separately viewed by use of a camera video recorder and monitor. For a transparent liquid on a reflective solid surface, thermocapillary convection in the drop, induced by evaporation, can be viewed nonintrusively, and the drop real-time profile data are synchronously recorded by video recording systems. Experimental results obtained from this technique clearly reveal that evaporation and thermocapillary convection greatly affect the spreading process and the characteristics of dynamic contact angle of the drop.

Dip coating of sol-gels

NASA Astrophysics Data System (ADS)

Schunk, P. R.; Hurd, A. J.; Brinker, C. J.

Dip coating is the primary means of depositing sol-gel films for precision optical coatings. Sols are typically multicomponent systems consisting of an inorganic phase dispersed in a solvent mixture, with each component differing in volatility and surface tension. This, together with slow coating speeds (less than 1cm/s), makes analysis of the coating process complicated; unlike most high-speed coating methods, solvent evaporation, evolving rheology, and surface tension gradients alter significantly the fluid mechanics of the deposition stage. These phenomena were studied with computer-aided predictions of the flow and species transport fields. The underlying theory involves mass, momentum, and species transport on a domain of unknown shape, with models and constitutive equations for vapor-liquid equilibria and surface tension. Due accounting is made for the unknown position of the free surface, which locates according to the capillary hydrodynamic forces and solvent loss by evaporation. Predictions of the effects of mass transfer, hydrodynamics, and surface tension gradients on final film thickness are compared with ellipsometry measurements of film thickness on a laboratory pilot coater. Although quantitative agreement is still lacking, both experiment and theory reveal that the film profile near the drying line takes on a parabolic shape.

Anomalous interfacial tension temperature dependence of condensed phase drops in magnetic fluids

NASA Astrophysics Data System (ADS)

Ivanov, Aleksey S.

2018-05-01

Interfacial tension temperature dependence σ(T) of the condensed phase (drop-like aggregates) in magnetic fluids undergoing field induced phase transition of the "gas-liquid" type was studied experimentally. Numerical analysis of the experimental data has revealed the anomalous (if compared to ordinary one-component fluids) behavior of the σ(T) function for all tested magnetic colloid samples: the condensed phase drops at high T ≈ 75 C exhibit higher σ(T) than the drops condensed at low T ≈ 20 C. The σ(T) behavior is explained by the polydispersity of magnetic colloids: at high T, only the largest colloidal particles are able to take part in the field induced condensation; thus, the increase of T causes the growth of the average particle diameters inside the drop-like aggregates, what in its turn results in the growth of σ(T). The result is confirmed by qualitative theoretical estimations and qualitative experimental observation of the condensed phase "evaporation" process after the applied magnetic field is removed: the drops that are formed due to capillary instability of the drop-like aggregates retract by one order of magnitude faster at high T, and the evaporation of the drops slows down at high T.

Experimental investigation on the thermal performance of a closed oscillating heat pipe in thermal management

NASA Astrophysics Data System (ADS)

Rao, Zhonghao; Wang, Qingchao; Zhao, Jiateng; Huang, Congliang

2017-10-01

To investigate the thermal performance of the closed oscillating heat pipe (OHP) as a passive heat transfer device in thermal management system, the gravitation force, surface tension, cooling section position and inclination angle were discussed with applied heating power ranging from 5 to 65 W. The deionized water was chosen as the working fluid and liquid-filling ratio was 50 ± 5%. The operation of the OHP mainly depends on the phase change of the working fluid. The working fluid within the OHP was constantly evaporated and cooled. The results show that the movement of the working fluid was similar to the forced damped mechanical vibration, it has to overcome the capillary resistance force and the stable oscillation should be that the OHP could successful startup. The oscillation frequency slowed and oscillation amplitude decreased when the inclination angle of the OHP increased. However, the thermal resistance increased. With the increment of the heating power, the average temperature of the evaporation and condensation section would be close. If the heating power was further increased, dry-out phenomenon within the OHP would appeared. With the decrement of the L, the start-up heating power also decreased and stable oscillation would be formed.

Understanding and controlling morphology evolution via DIO plasticization in PffBT4T-2OD/PC71BM devices

PubMed Central

Zhang, Yiwei; Parnell, Andrew J.; Pontecchiani, Fabio; Cooper, Joshaniel F. K.; Thompson, Richard L.; Jones, Richard A. L.; King, Stephen M.; Lidzey, David G.; Bernardo, Gabriel

2017-01-01

We demonstrate that the inclusion of a small amount of the co-solvent 1,8-diiodooctane in the preparation of a bulk-heterojunction photovoltaic device increases its power conversion efficiency by 20%, through a mechanism of transient plasticisation. We follow the removal of 1,8-diiodooctane directly after spin-coating using ellipsometry and ion beam analysis, while using small angle neutron scattering to characterise the morphological nanostructure evolution of the film. In PffBT4T-2OD/PC71BM devices, the power conversion efficiency increases from 7.2% to above 8.7% as a result of the coarsening of the phase domains. This coarsening process is assisted by thermal annealing and the slow evaporation of 1,8-diiodooctane, which we suggest, acts as a plasticiser to promote molecular mobility. Our results show that 1,8-diiodooctane can be completely removed from the film by a thermal annealing process at temperatures ≤100 °C and that there is an interplay between the evaporation rate of 1,8-diiodooctane and the rate of domain coarsening in the plasticized film which helps elucidate the mechanism by which additives improve device efficiency. PMID:28287164

Ocean Observations of Climate Change

NASA Astrophysics Data System (ADS)

Chambers, Don

2016-01-01

The ocean influences climate by storing and transporting large amounts of heat, freshwater, and carbon, and exchanging these properties with the atmosphere. About 93% of the excess heat energy stored by the earth over the last 50 years is found in the ocean. More than three quarters of the total exchange of water between the atmosphere and the earth's surface through evaporation and precipitation takes place over the oceans. The ocean contains 50 times more carbon than the atmosphere and is at present acting to slow the rate of climate change by absorbing one quarter of human emissions of carbon dioxide from fossil fuel burning, cement production, deforestation and other land use change.Here I summarize the observational evidence of change in the ocean, with an emphasis on basin- and global-scale changes relevant to climate. These include: changes in subsurface ocean temperature and heat content, evidence for regional changes in ocean salinity and their link to changes in evaporation and precipitation over the oceans, evidence of variability and change of ocean current patterns relevant to climate, observations of sea level change and predictions over the next century, and biogeochemical changes in the ocean, including ocean acidification.

Programmable solid state atom sources for nanofabrication.

PubMed

Han, Han; Imboden, Matthias; Stark, Thomas; del Corro, Pablo G; Pardo, Flavio; Bolle, Cristian A; Lally, Richard W; Bishop, David J

2015-06-28

In this paper we discuss the development of a MEMS-based solid state atom source that can provide controllable atom deposition ranging over eight orders of magnitude, from ten atoms per square micron up to hundreds of atomic layers, on a target ∼1 mm away. Using a micron-scale silicon plate as a thermal evaporation source we demonstrate the deposition of indium, silver, gold, copper, iron, aluminum, lead and tin. Because of their small sizes and rapid thermal response times, pulse width modulation techniques are a powerful way to control the atomic flux. Pulsing the source with precise voltages and timing provides control in terms of when and how many atoms get deposited. By arranging many of these devices into an array, one has a multi-material, programmable solid state evaporation source. These micro atom sources are a complementary technology that can enhance the capability of a variety of nano-fabrication techniques.

New Technique for Fabrication of Scanning Single-Electron Transistor Microscopy Tips

NASA Astrophysics Data System (ADS)

Goodwin, Eric; Tessmer, Stuart

Fabrication of glass tips for Scanning Single-Electron Transistor Microscopy (SSETM) can be expensive, time consuming, and inconsistent. Various techniques have been tried, with varying levels of success in regards to cost and reproducibility. The main requirement for SSETM tips is to have a sharp tip ending in a micron-scale flat face to allow for deposition of a quantum dot. Drawing inspiration from methods used to create tips from optical fibers for Near-Field Scanning Optical Microscopes, our group has come up with a quick and cost effective process for creating SSETM tips. By utilizing hydrofluoric acid to etch the tips and oleic acid to guide the etch profile, optical fiber tips with appropriate shaping can be rapidly prepared. Once etched, electric leads are thermally evaporated onto each side of the tip, while an aluminum quantum dot is evaporated onto the face. Preliminary results using various metals, oxide layers, and lead thicknesses have proven promising.

Determination of trace level bromate and perchlorate in drinking water by ion chromatography with an evaporative preconcentration technique.

PubMed

Liu, Yongjian; Mou, Shifen; Heberling, Shawn

2002-05-17

A simple sample preconcentration technique employing microwave-based evaporation for the determination of trace level bromate and perchlorate in drinking water with ion chromatography is presented. With a hydrophilic anion-exchange column and a sodium hydroxide eluent in linear gradient, bromate and perchlorate can be determined in one injection within 35 min. Prior to ion chromatographic analysis, the drinking water sample was treated with an OnGuard-Ag cartridge to remove the superfluous chloride and concentrated 20-fold using a PTFE beaker in a domestic microwave oven for 15 min. The recoveries of the anions ranged from 94.6% for NO2- to 105.2% for F-. The detection limits for bromate, perchlorate, iodate and chlorate were 0.1, 0.2, 0.1 and 0.2 microg/l, respectively. The developed method is applicable for the quantitation of bromate and perchlorate in drinking water samples.

Morphology, Structural and Dielectric Properties of Vacuum Evaporated V2O5 Thin Films

NASA Astrophysics Data System (ADS)

Sengodan, R.; Shekar, B. Chandar; Sathish, S.

Vanadium pentoxide (V2O5) thin films were deposited on well cleaned glass substrate using evaporation technique under the pressure of 10-5 Torr. The thickness of the films was measured by the multiple beam interferometry technique and cross checked by using capacitance method. Metal-Insulator-Metal (MIM) structure was fabricated by using suitable masks to study dielectric properties. The dielectric properties were studied by employing LCR meter in the frequency range 12 Hz to 100 kHz for various temperatures. The temperature co- efficient of permittivity (TCP), temperature co-efficient of capacitance (TCC) and dielectric constant (ɛ) were calculated. The activation energy was calculated and found to be very low. The activation energy was found to be increasing with increase in frequency. The obtained low value of activation energy suggested that the hopping conduction may be due to electrons rather than ions.

Low temperature MS2 (ATCC15597-B1) virus inactivation using a hot bubble column evaporator (HBCE).

PubMed

Garrido, A; Pashley, R M; Ninham, B W

2017-03-01

In the treatment of household wastewater viruses are hard to eliminate. A new technique is described which tackles this major problem. The MS2 (ATCC15597-B1) virus was used as a surrogate to estimate the inactivation rates for enteric viruses by a hot (150°C) air bubble column evaporator (HBCE) system Its surface charging properties obtained by dynamic light scattering, have been studied in a range of aqueous salt solutions and secondary treated synthetic sewage water. A combination of MS2 virus surface charge properties with thermal inactivation rates, and an improved double layer plaque assay technique, allows an assessment of the efficiency of the HBCE process for virus removal in water. The system is a new energy efficient treatment for water reuse applications. Copyright © 2016 Elsevier B.V. All rights reserved.

Lithium wall conditioning by high frequency pellet injection in RFX-mod

NASA Astrophysics Data System (ADS)

Innocente, P.; Mansfield, D. K.; Roquemore, A. L.; Agostini, M.; Barison, S.; Canton, A.; Carraro, L.; Cavazzana, R.; De Masi, G.; Fassina, A.; Fiameni, S.; Grando, L.; Rais, B.; Rossetto, F.; Scarin, P.

2015-08-01

In the RFX-mod reversed field pinch experiment, lithium wall conditioning has been tested with multiple scopes: to improve density control, to reduce impurities and to increase energy and particle confinement time. Large single lithium pellet injection, lithium capillary-pore system and lithium evaporation has been used for lithiumization. The last two methods, which presently provide the best results in tokamak devices, have limited applicability in the RFX-mod device due to the magnetic field characteristics and geometrical constraints. On the other side, the first mentioned technique did not allow injecting large amount of lithium. To improve the deposition, recently in RFX-mod small lithium multi-pellets injection has been tested. In this paper we compare lithium multi-pellets injection to the other techniques. Multi-pellets gave more uniform Li deposition than evaporator, but provided similar effects on plasma parameters, showing that further optimizations are required.

A New Experiment for Investigating Evaporation and Condensation of Cryogenic Propellants.

PubMed

Bellur, K; Médici, E F; Kulshreshtha, M; Konduru, V; Tyrewala, D; Tamilarasan, A; McQuillen, J; Leao, J; Hussey, D S; Jacobson, D L; Scherschligt, J; Hermanson, J C; Choi, C K; Allen, J S

2016-03-01

Passive and active technologies have been used to control propellant boil-off, but the current state of understanding of cryogenic evaporation and condensation in microgravity is insufficient for designing large cryogenic depots critical to the long-term space exploration missions. One of the key factors limiting the ability to design such systems is the uncertainty in the accommodation coefficients (evaporation and condensation), which are inputs for kinetic modeling of phase change. A novel, combined experimental and computational approach is being used to determine the accommodation coefficients for liquid hydrogen and liquid methane. The experimental effort utilizes the Neutron Imaging Facility located at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland to image evaporation and condensation of hydrogenated propellants inside of metallic containers. The computational effort includes numerical solution of a model for phase change in the contact line and thin film regions as well as an CFD effort for determining the appropriate thermal boundary conditions for the numerical solution of the evaporating and condensing liquid. Using all three methods, there is the possibility of extracting the accommodation coefficients from the experimental observations. The experiments are the first known observation of a liquid hydrogen menisci condensing and evaporating inside aluminum and stainless steel cylinders. The experimental technique, complimentary computational thermal model and meniscus shape determination are reported. The computational thermal model has been shown to accurately track the transient thermal response of the test cells. The meniscus shape determination suggests the presence of a finite contact angle, albeit very small, between liquid hydrogen and aluminum oxide.

A New Experiment for Investigating Evaporation and Condensation of Cryogenic Propellants

PubMed Central

Bellur, K.; Médici, E. F.; Kulshreshtha, M.; Konduru, V.; Tyrewala, D.; Tamilarasan, A.; McQuillen, J.; Leao, J.; Hussey, D. S.; Jacobson, D. L.; Scherschligt, J.; Hermanson, J. C.; Choi, C. K.; Allen, J. S.

2016-01-01

Passive and active technologies have been used to control propellant boil-off, but the current state of understanding of cryogenic evaporation and condensation in microgravity is insufficient for designing large cryogenic depots critical to the long-term space exploration missions. One of the key factors limiting the ability to design such systems is the uncertainty in the accommodation coefficients (evaporation and condensation), which are inputs for kinetic modeling of phase change. A novel, combined experimental and computational approach is being used to determine the accommodation coefficients for liquid hydrogen and liquid methane. The experimental effort utilizes the Neutron Imaging Facility located at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland to image evaporation and condensation of hydrogenated propellants inside of metallic containers. The computational effort includes numerical solution of a model for phase change in the contact line and thin film regions as well as an CFD effort for determining the appropriate thermal boundary conditions for the numerical solution of the evaporating and condensing liquid. Using all three methods, there is the possibility of extracting the accommodation coefficients from the experimental observations. The experiments are the first known observation of a liquid hydrogen menisci condensing and evaporating inside aluminum and stainless steel cylinders. The experimental technique, complimentary computational thermal model and meniscus shape determination are reported. The computational thermal model has been shown to accurately track the transient thermal response of the test cells. The meniscus shape determination suggests the presence of a finite contact angle, albeit very small, between liquid hydrogen and aluminum oxide. PMID:28154426

Lipase biofilm deposited by Matrix Assisted Pulsed Laser Evaporation technique

NASA Astrophysics Data System (ADS)

Aronne, Antonio; Bloisi, Francesco; Calabria, Raffaela; Califano, Valeria; Depero, Laura E.; Fanelli, Esther; Federici, Stefania; Massoli, Patrizio; Vicari, Luciano R. M.

2015-05-01

Lipase is an enzyme that finds application in biodiesel production and for detection of esters and triglycerides in biosensors. Matrix Assisted Pulsed Laser Evaporation (MAPLE), a technique derived from Pulsed Laser Deposition (PLD) for deposition of undamaged biomolecules or polymers, is characterized by the use of a frozen target obtained from a solution/suspension of the guest material (to be deposited) in a volatile matrix (solvent). The presence of the solvent avoids or at least reduces the potential damage of guest molecules by laser radiation but only the guest material reaches the substrate in an essentially solvent-free deposition. MAPLE can be used for enzymes immobilization, essential for industrial application, allowing the development of continuous processes, an easier separation of products, the reuse of the catalyst and, in some cases, enhancing enzyme properties (pH, temperature stability, etc.) and catalytic activity in non-aqueous media. Here we show that MAPLE technique can be used to deposit undamaged lipase and that the complex structure (due to droplets generated during extraction from target) of the deposited material can be controlled by changing the laser beam fluence.

Effect of evaporation on the shelf life of a universal adhesive.

PubMed

Pongprueksa, P; Miletic, V; De Munck, J; Brooks, N R; Meersman, F; Nies, E; Van Meerbeek, B; Van Landuyt, K L

2014-01-01

The purpose of this study was to evaluate how evaporation affects the shelf life of a one-bottle universal adhesive. Three different versions of Scotchbond Universal (SBU, 3M ESPE, Seefeld, Germany) were prepared using a weight-loss technique. SBU0 was left open to the air until maximal weight loss was obtained, whereas SBU50 was left open until 50% of evaporation occurred. In contrast, SBU100 was kept closed and was assumed to contain the maximum concentration of all ingredients. The degree of conversion (DC) was determined by using Fourier transform infrared spectroscopy on different substrates (on dentin or glass plate and mixed with dentin powder); ultimate microtensile strength and microtensile bond strength to dentin were measured as well. DC of the 100% solvent-containing adhesive (SBU100) was higher than that of the 50% (SBU50) and 0% (SBU0) solvent-containing adhesives for all substrates. DC of the adhesive applied onto glass and dehydrated dentin was higher than that applied onto dentin. Even though the ultimate microtensile strength of SBU0 was much higher than that of SBU50 and SBU100, its bond strength to dentin was significantly lower. Evaporation of adhesive ingredients may jeopardize the shelf life of a one-bottle universal system by reducing the degree of conversion and impairing bond strength. However, negative effects only became evident after more than 50% evaporation.

3D-Printed, All-in-One Evaporator for High-Efficiency Solar Steam Generation under 1 Sun Illumination.

PubMed

Li, Yiju; Gao, Tingting; Yang, Zhi; Chen, Chaoji; Luo, Wei; Song, Jianwei; Hitz, Emily; Jia, Chao; Zhou, Yubing; Liu, Boyang; Yang, Bao; Hu, Liangbing

2017-07-01

Using solar energy to generate steam is a clean and sustainable approach to addressing the issue of water shortage. The current challenge for solar steam generation is to develop easy-to-manufacture and scalable methods which can convert solar irradiation into exploitable thermal energy with high efficiency. Although various material and structure designs have been reported, high efficiency in solar steam generation usually can be achieved only at concentrated solar illumination. For the first time, 3D printing to construct an all-in-one evaporator with a concave structure for high-efficiency solar steam generation under 1 sun illumination is used. The solar-steam-generation device has a high porosity (97.3%) and efficient broadband solar absorption (>97%). The 3D-printed porous evaporator with intrinsic low thermal conductivity enables heat localization and effectively alleviates thermal dissipation to the bulk water. As a result, the 3D-printed evaporator has a high solar steam efficiency of 85.6% under 1 sun illumination (1 kW m -2 ), which is among the best compared with other reported evaporators. The all-in-one structure design using the advanced 3D printing fabrication technique offers a new approach to solar energy harvesting for high-efficiency steam generation. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Controlled delivery of tauroursodeoxycholic acid from biodegradable microspheres slows retinal degeneration and vision loss in P23H rats

PubMed Central

Lax, Pedro; Arranz-Romera, Alicia; Maneu, Victoria; Esteban-Pérez, Sergio; Pinilla, Isabel; Puebla-González, María del Mar; Herrero-Vanrell, Rocío

2017-01-01

Successful drug therapies for treating ocular diseases require effective concentrations of neuroprotective compounds maintained over time at the site of action. The purpose of this work was to assess the efficacy of intravitreal controlled delivery of tauroursodeoxycholic acid (TUDCA) encapsulated in poly(D,L-lactic-co-glycolic acid) (PLGA) microspheres for the treatment of the retina in a rat model of retinitis pigmentosa. PLGA microspheres (MSs) containing TUDCA were produced by the O/W emulsion-solvent evaporation technique. Particle size and morphology were assessed by light scattering and scanning electronic microscopy, respectively. Homozygous P23H line 3 rats received a treatment of intravitreal injections of TUDCA-PLGA MSs. Retinal function was assessed by electroretinography at P30, P60, P90 and P120. The density, structure and synaptic contacts of retinal neurons were analyzed using immunofluorescence and confocal microscopy at P90 and P120. TUDCA-loaded PLGA MSs were spherical, with a smooth surface. The production yield was 78%, the MSs mean particle size was 23 μm and the drug loading resulted 12.5 ± 0.8 μg TUDCA/mg MSs. MSs were able to deliver the loaded active compound in a gradual and progressive manner over the 28-day in vitro release study. Scotopic electroretinografic responses showed increased ERG a- and b-wave amplitudes in TUDCA-PLGA-MSs-treated eyes as compared to those injected with unloaded PLGA particles. TUDCA-PLGA-MSs-treated eyes showed more photoreceptor rows than controls. The synaptic contacts of photoreceptors with bipolar and horizontal cells were also preserved in P23H rats treated with TUDCA-PLGA MSs. This work indicates that the slow and continuous delivery of TUDCA from PLGA-MSs has potential neuroprotective effects that could constitute a suitable therapy to prevent neurodegeneration and visual loss in retinitis pigmentosa. PMID:28542454

Method of removing an immiscible lubricant from a refrigeration system and apparatus for same

DOEpatents

Spauschus, Hans O.; Starr, Thomas L.

1999-01-01

A method of separating an immiscible lubricant from a liquid refrigerant in a refrigerating system including a compressor, a condenser, an expansion device and an evaporator, wherein the expansion device is connected to the condenser by a liquid refrigerant flow line for liquid refrigerant and immiscible lubricant. The method comprising slowing the rate of flow of the liquid refrigerant and immiscible lubricant between the condenser and the expansion device such that the liquid refrigerant and the immiscible lubricant separate based upon differences in density. The method also comprises collecting the separated immiscible lubricant in a collection chamber in fluid communication with the separated immiscible lubricant. Apparatus for performing the method is also disclosed.

Mueller matrix spectroscopic ellipsometry study of chiral nanocrystalline cellulose films

NASA Astrophysics Data System (ADS)

Mendoza-Galván, Arturo; Muñoz-Pineda, Eloy; Ribeiro, Sidney J. L.; Santos, Moliria V.; Järrendahl, Kenneth; Arwin, Hans

2018-02-01

Chiral nanocrystalline cellulose (NCC) free-standing films were prepared through slow evaporation of aqueous suspensions of cellulose nanocrystals in a nematic chiral liquid crystal phase. Mueller matrix (MM) spectroscopic ellipsometry is used to study the polarization and depolarization properties of the chiral films. In the reflection mode, the MM is similar to the matrices reported for the cuticle of some beetles reflecting near circular left-handed polarized light in the visible range. The polarization properties of light transmitted at normal incidence for different polarization states of incident light are discussed. By using a differential decomposition of the MM, the structural circular birefringence and dichroism of a NCC chiral film are evaluated.

EPR and optical absorption study of Cu{sup 2+} doped lithium sulphate monohydrate (LSMH) single crystals

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

Sheela, K. Juliet; Subramanian, P., E-mail: psubramaniangri@gmail.com; Krishnan, S. Radha

2016-05-23

EPR study of Cu{sup 2+} doped NLO active Lithium Sulphate monohydrate (Li{sub 2}SO{sub 4.}H{sub 2}O) single crystals were grown successfully by slow evaporation method at room temperature. The principal values of g and A tensors indicate existence of orthorhombic symmetry around the Cu{sup 2+} ion. From the direction cosines of g and A tensors, the locations of Cu{sup 2+} in the lattice have been identified as interstitial site. Optical absorption confirms the rhombic symmetry and ground state wave function of the Cu{sup 2+} ion in a lattice as d{sub x2-y2}.

Evaporation induced 18O and 13C enrichment in lake systems: A global perspective on hydrologic balance effects

NASA Astrophysics Data System (ADS)

Horton, Travis W.; Defliese, William F.; Tripati, Aradhna K.; Oze, Christopher

2016-01-01

Growing pressure on sustainable water resource allocation in the context of global development and rapid environmental change demands rigorous knowledge of how regional water cycles change through time. One of the most attractive and widely utilized approaches for gaining this knowledge is the analysis of lake carbonate stable isotopic compositions. However, endogenic carbonate archives are sensitive to a variety of natural processes and conditions leaving isotopic datasets largely underdetermined. As a consequence, isotopic researchers are often required to assume values for multiple parameters, including temperature of carbonate formation or lake water δ18O, in order to interpret changes in hydrologic conditions. Here, we review and analyze a global compilation of 57 lacustrine dual carbon and oxygen stable isotope records with a topical focus on the effects of shifting hydrologic balance on endogenic carbonate isotopic compositions. Through integration of multiple large datasets we show that lake carbonate δ18O values and the lake waters from which they are derived are often shifted by >+10‰ relative to source waters discharging into the lake. The global pattern of δ18O and δ13C covariation observed in >70% of the records studied and in several evaporation experiments demonstrates that isotopic fractionations associated with lake water evaporation cause the heavy carbon and oxygen isotope enrichments observed in most lakes and lake carbonate records. Modeled endogenic calcite compositions in isotopic equilibrium with lake source waters further demonstrate that evaporation effects can be extreme even in lake records where δ18O and δ13C covariation is absent. Aridisol pedogenic carbonates show similar isotopic responses to evaporation, and the relevance of evaporative modification to paleoclimatic and paleotopographic research using endogenic carbonate proxies are discussed. Recent advances in stable isotope research techniques present unprecedented opportunities to overcome the underdetermined nature of stable isotopic data through integration of multiple isotopic proxies, including dual element 13C-excess values and clumped isotope temperature estimates. We demonstrate the utility of applying these multi-proxy approaches to the interpretation of paleohydroclimatic conditions in ancient lake systems. Understanding past, present, and future hydroclimatic systems is a global imperative. Significant progress should be expected as these modern research techniques become more widely applied and integrated with traditional stable isotopic proxies.

Structural colours of nickel bioreplicas of butterfly wings

NASA Astrophysics Data System (ADS)

Tolenis, Tomas; Swiontek, Stephen E.; Lakhtakia, Akhlesh

2017-04-01

The two-angle conformally evaporated-film-by-rotation technique (TA-CEFR) was devised to coat the wings of the monarch butterfly with nickel in order to form a 500-nm thick bioreplica thereof. The bioreplica exhibits structural colours that are completely obscured in actual wings by pigmental colours. Thus, the TA-CEFR technique provides a way to replicate, study and exploit hidden morphologies of biological surfaces.

Open software tools for eddy covariance flux partitioning

USDA-ARS?s Scientific Manuscript database

Agro-ecosystem management and assessment will benefit greatly from the development of reliable techniques for partitioning evapotranspiration (ET) into evaporation (E) and transpiration (T). Among other activities, flux partitioning can aid in evaluating consumptive vs. non-consumptive agricultural...

Inspecting cracks in foam insulation

NASA Technical Reports Server (NTRS)

Cambell, L. W.; Jung, G. K.

1979-01-01

Dye solution indicates extent of cracking by penetrating crack and showing original crack depth clearly. Solution comprised of methylene blue in denatured ethyl alcohol penetrates cracks completely and evaporates quickly and is suitable technique for usage in environmental or structural tests.

Cloud Processing of Secondary Organic Aerosol from Isoprene and Methacrolein Photooxidation.

PubMed

Giorio, Chiara; Monod, Anne; Brégonzio-Rozier, Lola; DeWitt, Helen Langley; Cazaunau, Mathieu; Temime-Roussel, Brice; Gratien, Aline; Michoud, Vincent; Pangui, Edouard; Ravier, Sylvain; Zielinski, Arthur T; Tapparo, Andrea; Vermeylen, Reinhilde; Claeys, Magda; Voisin, Didier; Kalberer, Markus; Doussin, Jean-François

2017-10-12

Aerosol-cloud interaction contributes to the largest uncertainties in the estimation and interpretation of the Earth's changing energy budget. The present study explores experimentally the impacts of water condensation-evaporation events, mimicking processes occurring in atmospheric clouds, on the molecular composition of secondary organic aerosol (SOA) from the photooxidation of methacrolein. A range of on- and off-line mass spectrometry techniques were used to obtain a detailed chemical characterization of SOA formed in control experiments in dry conditions, in triphasic experiments simulating gas-particle-cloud droplet interactions (starting from dry conditions and from 60% relative humidity (RH)), and in bulk aqueous-phase experiments. We observed that cloud events trigger fast SOA formation accompanied by evaporative losses. These evaporative losses decreased SOA concentration in the simulation chamber by 25-32% upon RH increase, while aqueous SOA was found to be metastable and slowly evaporated after cloud dissipation. In the simulation chamber, SOA composition measured with a high-resolution time-of-flight aerosol mass spectrometer, did not change during cloud events compared with high RH conditions (RH > 80%). In all experiments, off-line mass spectrometry techniques emphasize the critical role of 2-methylglyceric acid as a major product of isoprene chemistry, as an important contributor to the total SOA mass (15-20%) and as a key building block of oligomers found in the particulate phase. Interestingly, the comparison between the series of oligomers obtained from experiments performed under different conditions show a markedly different reactivity. In particular, long reaction times at high RH seem to create the conditions for aqueous-phase processing to occur in a more efficient manner than during two relatively short cloud events.

Experimental and Automated Analysis Techniques for High-resolution Electrical Mapping of Small Intestine Slow Wave Activity

PubMed Central

Angeli, Timothy R; O'Grady, Gregory; Paskaranandavadivel, Niranchan; Erickson, Jonathan C; Du, Peng; Pullan, Andrew J; Bissett, Ian P

2013-01-01

Background/Aims Small intestine motility is governed by an electrical slow wave activity, and abnormal slow wave events have been associated with intestinal dysmotility. High-resolution (HR) techniques are necessary to analyze slow wave propagation, but progress has been limited by few available electrode options and laborious manual analysis. This study presents novel methods for in vivo HR mapping of small intestine slow wave activity. Methods Recordings were obtained from along the porcine small intestine using flexible printed circuit board arrays (256 electrodes; 4 mm spacing). Filtering options were compared, and analysis was automated through adaptations of the falling-edge variable-threshold (FEVT) algorithm and graphical visualization tools. Results A Savitzky-Golay filter was chosen with polynomial-order 9 and window size 1.7 seconds, which maintained 94% of slow wave amplitude, 57% of gradient and achieved a noise correction ratio of 0.083. Optimized FEVT parameters achieved 87% sensitivity and 90% positive-predictive value. Automated activation mapping and animation successfully revealed slow wave propagation patterns, and frequency, velocity, and amplitude were calculated and compared at 5 locations along the intestine (16.4 ± 0.3 cpm, 13.4 ± 1.7 mm/sec, and 43 ± 6 µV, respectively, in the proximal jejunum). Conclusions The methods developed and validated here will greatly assist small intestine HR mapping, and will enable experimental and translational work to evaluate small intestine motility in health and disease. PMID:23667749

Solvent shift method for anti-precipitant screening of poorly soluble drugs using biorelevant medium and dimethyl sulfoxide.

PubMed

Yamashita, Taro; Ozaki, Shunsuke; Kushida, Ikuo

2011-10-31

96-well plate based anti-precipitant screening using bio-relevant medium FaSSIF (fasted-state simulated small intestinal fluid) is a useful technique for discovering anti-precipitants that maintain supersaturation of poorly soluble drugs. In a previous report, two disadvantages of the solvent evaporation method (solvent casting method) were mentioned: precipitation during the evaporation process and the use of volatile solvents to dissolve compounds. In this report, we propose a solvent shift method using DMSO (dimethyl sulfoxide). Initially, the drug substance was dissolved in DMSO at a high concentration and diluted with FaSSIF that contained anti-precipitants. To evaluate the validity of the method, itraconazole (ITZ) was used as the poorly soluble model drug. The solvent shift method resolved the disadvantages of the evaporation method, and AQOAT (HPMC-AS) was found as the most appropriate anti-precipitant for ITZ in a facile and expeditious manner when compared with the solvent evaporation method. In the large scale JP paddle method, AQOAT-based solid dispersion maintained a higher concentration than Tc-5Ew (HPMC)-based formulation; this result corresponded well with the small scale of the solvent shift method. Copyright © 2011 Elsevier B.V. All rights reserved.

Realization of single-phase BaSi2 films by vacuum evaporation with suitable optical properties and carrier lifetime for solar cell applications

NASA Astrophysics Data System (ADS)

Hara, Kosuke O.; Nakagawa, Yoshihiko; Suemasu, Takashi; Usami, Noritaka

2015-07-01

We have realized BaSi2 films by a simple vacuum evaporation technique for solar cell applications. X-ray diffraction analysis shows that single-phase BaSi2 films are formed on alkali-free glass substrates at 500 and 600 °C while impurity phases coexist on quartz or soda-lime glass substrates or at a substrate temperature of 400 °C. The mechanism of film growth is discussed by analyzing the residue on the evaporation boat. An issue on the fabricated films is cracking due to thermal mismatch, as observed by secondary electron microscopy. Optical characterizations by transmittance and reflectance spectroscopy show that the evaporated films have high absorption coefficients, reaching 2 × 104 cm-1 for a photon energy of 1.5 eV, and have indirect absorption edges of 1.14-1.21 eV, which are suitable for solar cells. The microwave-detected photoconductivity decay measurement reveals that the carrier lifetime is approximately 0.027 µs, corresponding to the diffusion length of 0.84 µm, which suggests the potential effective usage of photoexcited carriers.

Evaporation from Pinus caribaea plantations on former grassland soils under maritime tropical conditions

NASA Astrophysics Data System (ADS)

Waterloo, M. J.; Bruijnzeel, L. A.; Vugts, H. F.; Rawaqa, T. T.

1999-07-01

Wet canopy and dry canopy evaporation from young and mature plantations of Pinus caribaea on former grassland soils under maritime tropical conditions in southwestern Viti Levu, Fiji, were determined using micrometeorological and hydrological techniques. Modeled annual evaporation totals (ET) of 1926 and 1717 mm were derived for the 6- and the 15-year-old stands, respectively. Transpiration made up 72% and 70% of annual ET, and modeled rainfall interception by the trees and litter layer was 20-22% and 8-9% in the young and the mature stands respectively. Monthly ET was related to forest leaf area index and was much higher than that for the kind of tall fire-climax Pennisetum polystachyon grassland replaced by the forests. Grassland reforestation resulted in a maximum decrease in annual water yield of 1180 mm on a plot basis, although it is argued that a reduction of (at least) 500-700 mm would be more realistic at the catchment scale. The impact of reforesting grassland on the water resources in southwest Viti Levu is enhanced by its location in a maritime, seasonal climate in the outer tropics, which favors a larger difference between annual forest and grassland evaporation totals than do equatorial regions.

A slow fashion design model for bluejeans using house of quality approach

NASA Astrophysics Data System (ADS)

Nergis, B.; Candan, C.; Sarısaltık, S.; Seneloglu, N.; Bozuk, R.; Amzayev, K.

2017-10-01

The purpose of this study was to develop a slow fashion design model using the house of quality model (HOQ) to provide fashion designers a tool to improve the overall sustainability of denim jeans for Y generation consumers in Turkish market. In doing so, a survey was conducted to collect data on the design & performance expectations as well as the perception of slow fashion in design process of denim jeans of the targeted consumer group. The results showed that Y generation in the market gave the most importance to the sustainable production techniques when identifying slow fashion.

Terrestrial Fe-oxide Concretions and Mars Blueberries: Comparisons of Similar Advective and Diffusive Chemical Infiltration Reaction Mechanisms

NASA Astrophysics Data System (ADS)

Park, A. J.; Chan, M. A.

2006-12-01

Abundant iron oxide concretions occurring in Navajo Sandstone of southern Utah and those discovered at Meridiani Planum, Mars share many common observable physical traits such as their spheriodal shapes, occurrence, and distribution patterns in sediments. Terrestrial concretions are products of interaction between oxygen-rich aquifer water and basin-derived reducing (iron-rich) water. Water-rock interaction simulations show that diffusion of oxygen and iron supplied by slow-moving water is a reasonable mechanism for producing observed concretion patterns. In short, southern Utah iron oxide concretions are results of Liesegang-type diffusive infiltration reactions in sediments. We propose that the formation of blueberry hematite concretions in Mars sediments followed a similar diagenetic mechanism where iron was derived from the alteration of volcanic substrate and oxygen was provided by the early Martian atmosphere. Although the terrestrial analog differs in the original host rock composition, both the terrestrial and Mars iron-oxide precipitation mechanisms utilize iron and oxygen interactions in sedimentary host rock with diffusive infiltration of solutes from two opposite sources. For the terrestrial model, slow advection of iron-rich water is an important factor that allowed pervasive and in places massive precipitation of iron-oxide concretions. In Mars, evaporative flux of water at the top of the sediment column may have produced a slow advective mass-transfer mechanism that provided a steady source and the right quantity of iron. The similarities of the terrestrial and Martian systems are demonstrated using a water-rock interaction simulator Sym.8, initially in one-dimensional systems. Boundary conditions such as oxygen content of water, partial pressure of oxygen, and supply rate of iron were varied. The results demonstrate the importance of slow advection of water and diffusive processes for producing diagenetic iron oxide concretions.

Metabolomics and the Legacy of Previous Ecosystems: a Case Study from the Brine of Lake Vida (Antarctica)

NASA Astrophysics Data System (ADS)

Chou, L.; Kenig, F. P. H.; Murray, A. E.; Doran, P. T.; Fritsen, C. H.

2015-12-01

The McMurdo Dry Valleys of Antarctica are regarded as one of the best Earth analogs for astrobiological investigations of icy worlds. In the dry valleys, Lake Vida contains an anoxic and aphotic ice-sealed brine that has been isolated for millennia and yet is hosting a population of active microbes at -13˚ C. The biogeochemical processes used by these slow-growing microbes are still unclear. We attempt to elucidate the microbial processes responsible for the survivability of these organisms using metabolomics. Preliminary investigations of organic compounds of Lake Vida Brine (LVBr) was performed using gas chromatography-mass spectrometry (GC-MS) and solid-phase micro-extraction (SPME) GC-MS. LVBr contains a vast variety of lipids and is dominated by low molecular weight compounds. Many of these compounds are biomarkers of processes that took place in Lake Vida prior to evaporation and its cryo-encapsulation. These compounds include dimethylsulfide that is derived from the photosynthate dimethylsulfoniopropionate, dihydroactinidiolide that is derived from a diatom pigment, and 2-methyl-3-ethyl-maleimide that is derived from chlorophyll. These compounds, which dominate the lipid reservoir, represent a legacy from an ecosystem that is different from the current bacterial ecosystem of the brine. The abundance of the legacy compounds in the brine is most likely a reflection of the very slow metabolism of the bacterial community in the cold brine. It is important, thus, to be able to distinguish the legacy metabolites and their diagenetic products from the metabolites of the current ecosystem. This legacy issue is specific to a slow growing microbial ecosystem that cannot process the legacy carbon completely. It applies not only to Lake Vida brine, but other slow growing ecosystems such as other subglacial Antarctic lakes, the Arctic regions, and the deep biosphere.

Solid State Reaction of Thin Metal Films with MERCURY(1-X)CADMIUM(X)TELLURIDE.

NASA Astrophysics Data System (ADS)

Ehsani, Hassan

The solid state reactions of both e-beam evaporation and sputter deposition of thin layers of Cu, Co, and Ni onto CdTe and Hg_{0.8}Cd _{0.2}Te have been investigated using Transmission Electron Microscopy and Auger Electron Spectroscopy. For a Cu overlayer deposited by either method on CdTe(111) and Hg_{0.8}Cd _{0.2}Te substrates, we observed formation of a relatively thick region of Cu _{rm 2-x}Te (superlattice structure), even though the heat of reactions ( DeltaH_{rm R} ) are positive as calculated using bulk parameters. Deposition of Co onto Hg_{0.8 }Cd_{0.2}Te substrates reacted to form the gamma -phase (Co_3Te_4) at room temperature in the case of deposition by sputtering, and at 150^circC annealing temperature in the case of deposition by e-beam evaporation. This compound was stable at room and elevated temperatures (100 ^circC, 200^ circC, 300^circC, and 400^circC). On the other hand Co did not react with CdTe (at temperature less than 300^circC) instead, generation of Te was observed. The Te generated in the case of sputter deposition and fast deposition (8-10A) e-beam evaporation was polycrystalline whereas, in the case of slow deposition (0.3-0.5A) e-beam evaporation it was amorphous. Auger depth profile indicated that the amount of excess Te in the case of sputter deposition was larger in compared with deposition by e-beam evaporation. The excess Te was distributed throughout the Co film. The results of Ni deposited onto Hg_ {0.8}Cd_{0.2} Te or CdTe substrate were somewhat similar to the Co cases. Ni reacted with Hg_{0.8 }Cd_{0.2}Te at room temperature in either deposition system to form the delta-phase (NiTe-Ni _2Te). From the results of this work it is clear that the solid produced as a result of either e-beam or sputter deposition has a higher free energy than that of a metal layer on contact with the substrate. This result indicates importance of kinetics in the formation of the interface structure of metals deposited on Hg_{0.8 }Cd_{0.2}Te substrates. (Abstract shortened with permission of author.).

Optical nonlinearity of D-A-π-D and D-A-π-A type of new chalcones for potential applications in optical limiting and density functional theory studies

NASA Astrophysics Data System (ADS)

Chandra Shekhara Shetty, T.; Chidan Kumar, C. S.; Gagan Patel, K. N.; Chia, Tze Shyang; Dharmaprakash, S. M.; Ramasami, Ponnadurai; Umar, Yunusa; Chandraju, Siddegowda; Quah, Ching Kheng

2017-09-01

Two new chalcones namely, (2E)-1-(3-fluoro-4-methoxyphenyl)-3-(4-methoxyphenyl) prop-2-en-1-one and (2E)-3-(4-chlorophenyl)-1-(3-fluoro-4-methoxyphenyl)prop-2-en-1-one were synthesized and grown as single crystals by slow evaporation technique in methanol. The FTIR spectrum recorded confirms the presence of functional groups in these materials. The molecular conformation of the compounds was achieved by single crystal X-ray diffraction studies. The thermal stability of the crystals was determined from TGA/DSC curve. The third order optical nonlinearity of the chalcone compounds in DMF solution has been carried out using an Nd:YAG laser at 532 nm as the source of excitation. The nonlinear optical response was characterized by measuring the intensity dependent refractive index n2 of the medium using Z-scan technique. It is seen that the molecules exhibit a negative (defocusing) nonlinearity and large nonlinear refractive index of the order of -1.8 × 10-11 esu. The third-order nonlinearity of the studied chalcones is dominated by nonlinear refraction, which leads to strong optical limiting of laser. The result reveals that these two new chalcone molecules would be a promising material for optical limiting applications. In addition, the optimized molecular geometry, vibrational frequencies in gas, and the Molecular Electrostatic Potential (MEP) surface parameters of the two molecules were calculated using DFT/B3LYP method with 6-311++G(d,p) basis set in ground state. All the theoretical calculations were found in good agreement with experimental data.

Growth, spectral and optical characterization of a novel nonlinear optical organic material: D-Alanine DL-Mandelic acid single crystal

NASA Astrophysics Data System (ADS)

Jayaprakash, P.; Mohamed, M. Peer; Caroline, M. Lydia

2017-04-01

An organic nonlinear optical single crystal, D-alanine DL-mandelic acid was synthesized and successfully grown by slow evaporation solution growth technique at ambient temperature using solvent of aqueous solution. The unit cell parameters were assessed from single crystal X-ray diffraction analysis. The presence of diverse functional groups and vibrational modes were identified using Fourier Transform Infra Red and Fourier Transform Raman spectral analyses. The chemical structure of grown crystal has been identified by Nuclear Magnetic Resonance spectroscopic study. Ultraviolet-visible spectral analysis reveal that the crystal has lower cut-off wavelength down to 259 nm, is a key factor to exhibit second harmonic generation signal. The electronic optical band gap and Urbach energy is calculated as 5.31 eV and 0.2425 eV respectively from the UV absorption profile. The diverse optical properties such as, extinction coefficient, reflectance, linear refractive index, optical conductivity was calculated using UV-visible data. The relative second harmonic efficiency of the compound is found to be 0.81 times greater than that of KH2PO4 (KDP). The thermal stability of the grown crystal was studied by thermogravimetric analysis and differential thermal analysis techniques. The luminescence spectrum exhibited two peaks (520 nm, 564 nm) due to the donation of protons from carboxylic acid to amino group. The Vickers microhardness test was carried out employing one of the as-grown hard crystal and there by hardness number (Hv), Meyer's index (n), yield strength (σy), elastic stiffness constant (C11) and Knoop hardness number (HK) were assessed. The dielectric behaviour of the as-grown crystal was analyzed for different temperatures (313 K, 333 K, 353 K, and 373 K) at different frequencies.

Crystal growth and characterization of semi-organic 2-amino-5-nitropyridinium bromide (2A5NPBr) single crystals for third-order nonlinear optical (NLO) applications

NASA Astrophysics Data System (ADS)

Vediyappan, Sivasubramani; Arumugam, Raja; Pichan, Karuppasamy; Kasthuri, Ramachandran; Muthu, Senthil Pandian; Perumal, Ramasamy

2017-12-01

Semi-organic nonlinear optical (NLO) 2-amino-5-nitropyridinium bromide (2A5NPBr) single crystals have been grown by slow evaporation solution technique (SEST) with the growth period of 60 days. The single-crystal XRD analysis confirms the unit cell parameters of the grown crystal. The crystallinity of grown 2A5NPBr was analyzed by powder X-ray diffraction (PXRD) measurement. The presence of functional groups of 2A5NPBr crystal was confirmed by Fourier transform infrared (FTIR) spectrum analysis. The optical transmittance of the grown crystal was analyzed by UV-Vis-NIR analysis. It shows good transparency in the visible and NIR region and it is favorable for nonlinear optical (NLO) device applications. The chemical etching study was carried out and it reveals that the grown crystal has less dislocation density. The photoconductivity study reveals that the grown crystal possesses positive photoconductive nature. The thermal stability of the crystal has been investigated by thermogravimetric (TG) and differential thermal analysis (DTA). The dielectric constant and dielectric loss as a function of frequency were measured. The electronic polarizability (α) of 2A5NPBr molecule has been calculated theoretically by different ways such as Penn analysis, Clausius-Mossotti relation, Lorentz-Lorenz equation, optical bandgap, and coupled dipole method (CDM). The obtained values of electronic polarizability (α) are in good agreement with each other. Laser damage threshold (LDT) of 2A5NPBr crystal has been measured using Nd:YAG laser with the wavelength of 1064 nm. Third-order nonlinear optical property of the grown crystal was studied by Z-scan technique using He-Ne laser of wavelength 632.8 nm.

Influence of bis-thiourea nickel nitrate on the structural, optical, electrical, thermal and mechanical behavior of a KDP single crystal for NLO applications

NASA Astrophysics Data System (ADS)

Rasal, Y. B.; Shaikh, R. N.; Shirsat, M. D.; Kalainathan, S.; Hussaini, S. S.

2017-03-01

A single crystal of bis-thiourea nickel nitrate (BTNN) doped potassium dihydrogen phosphate (KDP) has been grown from solution at room temperature by a slow evaporation technique. The cell parameters of the grown crystals were determined using single crystal x-ray diffraction analysis. The different functional groups of the grown crystal were confirmed using Fourier transform infrared analysis. The improved optical parameters of the grown crystal have been evaluated in the range of 200-900 nm using UV-visible spectral analysis. The grown crystal was transparent in the entire visible region and the band gap value was found to be 4.96 eV. The influence of BTNN on the third order nonlinear optical properties of KDP crystal has been investigated by means of the Z-scan technique. The second harmonic generation (SHG) efficiency of grown crystal measured using a Nd-YAG laser is 1.98 times higher than that of pure KDP. The third order nonlinear optical susceptibility (χ 3) and nonlinear absorption coefficient (β) of BTNN doped KDP crystal is found to be 1.77  ×  10-5 esu and 5.57  ×  10-6 cm W-1 respectively. The laser damage threshold (LDT) energy for the grown crystal has been measured by using a Q-switched Nd:YAG laser source. The bis-thiourea nickel nitrate shows authoritative impact on the dielectric properties of doped crystal. The influence of bis-thiourea nickel nitrate on the mechanical behavior of KDP crystal has been investigated using Vickers microhardness intender. The thermal behavior of BTNN doped KDP crystal has been analyzed by TGA/DTA analysis.

Key functions analysis of a novel nonlinear optical D-π-A bridge type (2E)-3-(4-Methylphenyl)-1-(3-nitrophenyl) prop-2-en-1-one chalcone: An experimental and theoretical approach

NASA Astrophysics Data System (ADS)

Patil, Parutagouda Shankaragouda; Shkir, Mohd; Maidur, Shivaraj R.; AlFaify, S.; Arora, M.; Rao, S. Venugopal; Abbas, Haider; Ganesh, V.

2017-10-01

In the current work a new third-order nonlinear optical organic single crystal of (2E)-3-(4-Methylphenyl)-1-(3-nitrophenyl) prop-2-en-1-one (ML3NC) has been grown with well-defined morphology using the slow evaporation solution growth technique. X-ray diffraction technique was used to confirm the crystal system. The presence of functional groups in the molecular structure was identified by robust FT-IR and FT-Raman spectra by experimental and theoretical analysis. The ultraviolet-visible-near infrared and photoluminescence studies shows that the grown crystals possess excellent transparency window and green emission band (∼560 nm) confirms their use in green OLEDs. The third-order nonlinear and optical limiting studies have been performed using femtosecond (fs) Z-scan technique. The third-order nonlinear optical susceptibility (χ(3)), second-order hyperpolarizability (γ), nonlinear refractive index (n2) and limiting threshold values are found to be 4.03 × 10-12 esu, 14.2 × 10-32 esu, -4.33 × 10-14 cm2/W and 2.41 mJ/cm2, respectively. Furthermore, the quantum chemical studies were carried out to achieve the ground state molecular geometry and correlate with experimental results. The experimental value of absorption wavelength (λabs = 328 nm) is found to be in excellent accord with the theoretical value (λabs = 328 nm) at TD-DFT/B3LYP/6-31G* level of theory. To understand the static and dynamic NLO behavior, the polarizability (α) and second hyperpolarizability (γ) values were determined using TD-HF method. The computed second hyperpolarizability γ(-3ω; ω,ω,ω) at 800 nm wavelength was found to be 0.499 × 10-32 esu which is in good agreement with experimental value at the same wavelength. These results confirms the applied nature of title molecule in optoelectronic and nonlinear optical devices.

Crystal growth, structural, spectral, thermal, linear and nonlinear optical characterization of a new organic nonlinear chiral compound: L-tryptophan-fumaric acid-water (1/1/1) suitable for laser frequency conversion

NASA Astrophysics Data System (ADS)

Peer Mohamed, M.; Jayaprakash, P.; Nageshwari, M.; Rathika Thaya Kumari, C.; Sangeetha, P.; Sudha, S.; Mani, G.; Lydia Caroline, M.

2017-08-01

A new organic active nonlinear optical crystal L-tryptophan fumaric acid water (1/1/1), (C15H17N2 O7. H2O)(LTFAW), consisting of zwitterion tryptophan molecule in conjunction with a fumaric acid molecule and a water molecule was grown by slow solvent evaporation technique from aqueous solution. The organic chromophore crystallizes from water in its zwitterions exhibiting tabular habit in monoclinic system with acentric space group C2 (Z = 4). The sharp peaks observed in Powder X-ray diffractogram depicts the crystalline nature. The presence of functional groups in the grown crystal was analyzed using FT-IR spectrum. The carbon and hydrogen environment in molecular structure was investigated using FT-NMR technique using deuterated DMSO solution. Ultraviolet-visible spectral analysis reveal that the crystal possess lower cut-off wavelength down to 275 nm, is a key factor to exhibit Second Harmonic Generation (SHG) signal. The direct optical band gap is evaluated to be 5.28 eV from the UV absorption profile. The evaluation of optical constants by employing UV-visible absorbance data such as, extinction coefficient, reflectance, refractive index, optical conductivity are supportive towards good performance as NLO devices. Temperature of decomposition was investigated using thermogravimetric analysis/differential thermal analysis techniques (TG/DTA). The luminescence profile exhibited two peaks (362 nm, 683 nm) due to the donation of protons from carboxylic group to amino group. The nonlinear optical behavior from the noncentrosymmetric crystal was observed by the generation of frequency doubled (2ω) optical radiation when subjected to pulsed Nd:YAG laser (1064 nm, 10 ns, 10 Hz) using Kurtz-Perry method. The variation of dielectric constant (εʹ) and dielectric loss (εʹʹ) vs. Log f for the title compound was analysed at a few selected temperatures and frequencies.

Statistical optimization of controlled release microspheres containing cetirizine hydrochloride as a model for water soluble drugs.

PubMed

El-Say, Khalid M; El-Helw, Abdel-Rahim M; Ahmed, Osama A A; Hosny, Khaled M; Ahmed, Tarek A; Kharshoum, Rasha M; Fahmy, Usama A; Alsawahli, Majed

2015-01-01

The purpose was to improve the encapsulation efficiency of cetirizine hydrochloride (CTZ) microspheres as a model for water soluble drugs and control its release by applying response surface methodology. A 3(3) Box-Behnken design was used to determine the effect of drug/polymer ratio (X1), surfactant concentration (X2) and stirring speed (X3), on the mean particle size (Y1), percentage encapsulation efficiency (Y2) and cumulative percent drug released for 12 h (Y3). Emulsion solvent evaporation (ESE) technique was applied utilizing Eudragit RS100 as coating polymer and span 80 as surfactant. All formulations were evaluated for micromeritic properties and morphologically characterized by scanning electron microscopy (SEM). The relative bioavailability of the optimized microspheres was compared with CTZ marketed product after oral administration on healthy human volunteers using a double blind, randomized, cross-over design. The results revealed that the mean particle sizes of the microspheres ranged from 62 to 348 µm and the efficiency of entrapment ranged from 36.3% to 70.1%. The optimized CTZ microspheres exhibited a slow and controlled release over 12 h. The pharmacokinetic data of optimized CTZ microspheres showed prolonged tmax, decreased Cmax and AUC0-∞ value of 3309 ± 211 ng h/ml indicating improved relative bioavailability by 169.4% compared with marketed tablets.

Synthesis, growth, structural and optical studies of a new organic three dimensional framework: 4-(aminocarbonyl)pyridine 4-(aminocarbonyl)pyridinium hydrogen L-malate

NASA Astrophysics Data System (ADS)

Vijayalakshmi, A.; Vidyavathy, B.; Peramaiyan, G.; Vinitha, G.

2017-02-01

4-(aminocarbonyl)pyridine 4-(aminocarbonyl)pyridinium hydrogen L-malate [(4ACP)(4ACP).(LM)] a new organic nonlinear optical (NLO) crystal was grown by the slow evaporation method. Single crystal X-ray diffraction analysis revealed that the [(4ACP)(4ACP).(LM)] crystal belongs to monoclinic crystal system, space group P21/n, with a three dimensional network. Thermogravimetry (TG) and differential thermal (DT) analyses showed that [(4ACP)(4ACP).(LM)] is thermally stable up to 165 °C. The optical transmittance window and the lower cut-off wavelength of [(4ACP)(4ACP).(LM)] were found out by UV-vis-NIR spectral study. The molecular structure of [(4ACP)(4ACP).(LM)] was further confirmed by FTIR spectral studies. The relative dielectric permittivity and dielectric loss were determined as function of frequency and temperature. The third order nonlinear optical property of [(4ACP)(4ACP).(LM)] was studied by the Z-scan technique using a 532 nm diode pumped CW Nd:YAG laser. Nonlinear refractive index, nonlinear absorption coefficient and third order nonlinear susceptibility of the grown crystal were found to be 7.38×10-8 cm2/W, 0.08×10-4 cm/W and 5.36×10-6 esu, respectively. The laser damage threshold value is found to be 1.75 GW/cm2

Synthesis, nucleation, growth, structural, spectral, thermal, linear and nonlinear optical studies of novel organic NLO crystal: 4-fluoro 4-nitrostilbene (FONS).

PubMed

Dinakaran, Paul M; Kalainathan, S

2013-03-15

A novel organic nonlinear optical material 4-fluoro 4-nitrostilbene (FONS), with molecular formula (C(14)H(10)FNO(2)) has been synthesized. Using ethyl methyl ketone as solvent, the synthesized material has been repeatedly recrystallized to minimize the impurities and good optical quality single crystals were harvested by slow evaporation method. Single crystal X-ray diffraction analysis reveals that the grown FONS crystal belongs to monoclinic system with noncentrosymmetric space group "P2(1)". The powder X-ray diffraction pattern of FONS has been recorded. Functional groups of the title compound were confirmed by FTIR and the molecular structure was confirmed by (1)HNMR. The UV-vis-NIR absorption study reveals no absorption in the visible region and the cut-off wavelength was found to be at 408 nm. Optical band gap (E(g)) of the grown crystal was found to be 3.27 eV and also the optical constants were determined. Thermal behaviour of the FONS has been studied by TGA/DTA analyses. From the mass spectrum, the ratio of compound formation of FONS was analyzed. The NLO property has been confirmed by Kurtz and Perry powder SHG technique and the SHG efficiency of FONS (262 mV) crystal was found to be 12 times greater than that of KDP (21.7 mV). Copyright © 2013 Elsevier B.V. All rights reserved.

Antimicrobial activity and second harmonic studies on organic non-centrosymmetric pure and doped ninhydrin single crystals

NASA Astrophysics Data System (ADS)

Prasanyaa, T.; Jayaramakrishnan, V.; Haris, M.

2013-03-01

In this paper, we report the successful growth of pure, Cu2+ ions and Cd2+ ions doped on ninhydrin single crystals by slow solvent evaporation technique. The presence of Cu2+ and Cd2+ ions in the specimen of ninhydrin single crystal has been determined by atomic absorption spectroscopy. The powder X-ray diffraction analysis was done to calculate the lattice parameters of the pure and doped crystals. The percentage of transmittance of the crystal was recorded using the UV-Vis Spectrophotometer. Thermal behaviors of the grown crystals have been examined by the thermal gravimetric/differential thermal analysis. The hardness of the grown crystals was assessed and the results show the minor variation in the hardness value for the pure and doped ninhydrin samples. The value of the work hardening coefficient n was found to be 2.0, 1.0 and 1.06 for pure, copper and cadmium doped ninhydrin crystals respectively. The second harmonic generation efficiency of Cd2+ and Cu2+ doped ninhydrin is 8.3 and 6.3 times greater than well known nonlinear crystal of potassium dihydrogen phosphate respectively. The antibacterial and antifungal activities of the title compound were performed by disk diffusion method against the standard bacteria Escherichia coli, Xanthomonas oryzae and against the fungus Aspergillis niger and Aspergillus flavus.

Growth and characterization of a new nonlinear optical organic crystal: 2,4,6-Trimethylacetanilide

NASA Astrophysics Data System (ADS)

Upadhyaya, V.; Prabhu, Sharada G.

2015-09-01

A new nonlinear optical organic material, 2,4,6-trimethylacetanilide (246TMAA), also known as N-[2,4,6- trimethylphenyl]acetamide, has been synthesized and grown as a single crystal by the slow evaporation technique by organic solvents. The grown crystals have been characterized by morphology study. The crystals are prismatic. Surface examination shows granular dendritic pattern in optical micrograph. The Scanning Electron Micrograph shows the layered growth of the crystal. The Differential Scanning Calorimeter plot shows no phase change until melting point (219°C). The density of the crystals is 1.1g/cc and the crystals are soft. The crystals are transparent in the visible region and in the ultra-violet region till 280 nm. 246TMAA crystallizes with 2 molecules in a monoclinic unit cell in the noncentrosymmetric point group m, space group Pn. Refractive indices of this optically biaxial crystal along the three crystallophysical axes have been measured at 633 nm. The optical second harmonic generation efficiency of the crystal at 1064 nm is about half that of the urea crystal, measured by powder method using Nd:YAG laser. The results show that the 246TMAA crystal can efficiently be used for up-conversion of infrared radiation into visible green light. The powder X-ray diffraction spectrum of the crystal has been obtained.

Antimicrobial activity and second harmonic studies on organic non-centrosymmetric pure and doped ninhydrin single crystals.

PubMed

Prasanyaa, T; Jayaramakrishnan, V; Haris, M

2013-03-01

In this paper, we report the successful growth of pure, Cu(2+) ions and Cd(2+) ions doped on ninhydrin single crystals by slow solvent evaporation technique. The presence of Cu(2+) and Cd(2+) ions in the specimen of ninhydrin single crystal has been determined by atomic absorption spectroscopy. The powder X-ray diffraction analysis was done to calculate the lattice parameters of the pure and doped crystals. The percentage of transmittance of the crystal was recorded using the UV-Vis Spectrophotometer. Thermal behaviors of the grown crystals have been examined by the thermal gravimetric/differential thermal analysis. The hardness of the grown crystals was assessed and the results show the minor variation in the hardness value for the pure and doped ninhydrin samples. The value of the work hardening coefficient n was found to be 2.0, 1.0 and 1.06 for pure, copper and cadmium doped ninhydrin crystals respectively. The second harmonic generation efficiency of Cd(2+) and Cu(2+) doped ninhydrin is 8.3 and 6.3 times greater than well known nonlinear crystal of potassium dihydrogen phosphate respectively. The antibacterial and antifungal activities of the title compound were performed by disk diffusion method against the standard bacteria Escherichia coli, Xanthomonas oryzae and against the fungus Aspergillis niger and Aspergillus flavus. Copyright © 2012 Elsevier B.V. All rights reserved.

Synthesis, crystal growth, single crystal X-ray analysis and vibrational spectral studies of (2E)-3-(2-chloro-4-fluorophenyl)-1-(3,4-dimethoxyphenyl)prop-2-en-1-one: A combined DFT study

NASA Astrophysics Data System (ADS)

Chidan Kumar, C. S.; Balachandran, V.; Fun, Hoong-Kun; Chandraju, Siddegowda; Quah, Ching Kheng

2015-11-01

A new chalcone derivative, (2E)-3-(2-chloro-4-fluorophenyl)-1-(3,4-dimethoxyphenyl)prop-2-en-1-one (a) was synthesized and single crystals were grown by slow evaporation technique. The FT-Raman and FT-IR spectra of the sample were recorded in the region 3500-100 cm-1 and 4000-400 cm-1 respectively. The spectra were interpreted with the aid of normal coordinate analysis, following structure optimizations and force field calculations based on B3LYP/6-31G (d) level of theory. Normal coordinate calculations were performed using the DFT force field corrected by a recommended set of scaling factors yielding fairly good agreement between the observed and calculated wavenumbers. The total electron density and molecular electrostatic potential surfaces of the molecule were constructed using B3LYP/6-31G (d) method to display electrostatic potential (electron + nuclei) distribution, molecular shape, size, and dipole moments of the molecule. HOMO and LUMO energies were also calculated. Stability of the molecule arising from hyperconjugative interactions and charge delocalization has been analyzed using natural bond orbital (NBO) analysis. Global and local reactivity descriptors and dipole moment (μ), static polarizability (α), first order hyperpolarizability (β) and optical gap (ΔE) were also calculated to study the NLO property of our title compound.

Supramolecular network through Nsbnd H…O, Osbnd H…O and Csbnd H…O hydrogen bonding interaction and density functional theory studies of 4-methylanilinium-3-carboxy-4-hydroxybenzenesulphonate crystal

NASA Astrophysics Data System (ADS)

Rajkumar, M.; Muthuraja, P.; Dhandapani, M.; Chandramohan, A.

2018-02-01

By utilizing the hydrogen bonding strategy, 4-methylanilinium-3-hydroxy-4-corboxy-benzenesulphonate (4MABS), an organic proton transfer molecular salt was synthesized and single crystals of it were successfully grown by slow solvent evaporation solution growth technique at ambient temperature. The 1H and 13C NMR spectra were recorded to establish the molecular structure of the title salt. The single crystal XRD analysis reveals that the title salt crystallizes in monoclinic crystal system with centrosymmetric space group, P21/n. Further, the title salt involves extensive intermolecular Nsbnd H…O, Osbnd H…O and Csbnd H…O as well as intramolecular Osbnd H…O hydrogen bonding interactions to construct supramolecular architecture. All quantum chemical calculations were performed at the level of density functional theory (DFT) with B3LYP functional using 6-311G (d,p) basis atomic set. The photoluminescence spectrum was recorded to explore the emission property of the title crystal. The presence of the various vibrational modes and functional groups in the synthesized salt was confirmed by FT-IR studies. The thermal behaviour of title crystal was established employing TG/DTA analyses. The mechanical properties of the grown crystal were determined by Vicker's microhardness studies. Dielectric measurements were carried out on the grown crystal at a different temperature to evaluate electrical properties.

Study the Effect of Substrate Temperature on Structural and Electrical Properties of Electron Beam Evaporated In{sub 1−x}Sb{sub x} Thin Films

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

Rahul, E-mail: rhl.jaunpur@gmail, E-mail: srvfzb@rediffmail.com; Vishwakarma, S. R., E-mail: rhl.jaunpur@gmail, E-mail: srvfzb@rediffmail.com; Verma, Aneet Kumar, E-mail: rhl.jaunpur@gmail, E-mail: srvfzb@rediffmail.com

2011-10-20

Indium Antimonide (InSb) is a promising materials for mid and long wavelength infrared and high speed devices applications because of its small band gap. The Indium Antimonide (InSb) thin films have been deposited onto well cleaned glass substrate at different substrate temperatures (300 K, 323 K, 373 K) by electron beam evaporation technique in the high vacuum chamber at vacuum pressure ∼10{sup −5} torr using prepared non‐stoichiometric InSb powder using formula In{sub 1−x}Sb{sub x}(0.2

Vapor Flow Patterns During a Start-Up Transient in Heat Pipes

NASA Technical Reports Server (NTRS)

Issacci, F.; Ghoniem, N, M.; Catton, I.

1996-01-01

The vapor flow patterns in heat pipes are examined during the start-up transient phase. The vapor core is modelled as a channel flow using a two dimensional compressible flow model. A nonlinear filtering technique is used as a post process to eliminate the non-physical oscillations of the flow variables. For high-input heat flux, multiple shock reflections are observed in the evaporation region. The reflections cause a reverse flow in the evaporation and circulations in the adiabatic region. Furthermore, each shock reflection causes a significant increase in the local pressure and a large pressure drop along the heat pipe.

The energy balance within a bubble column evaporator

NASA Astrophysics Data System (ADS)

Fan, Chao; Shahid, Muhammad; Pashley, Richard M.

2018-05-01

Bubble column evaporator (BCE) systems have been studied and developed for many applications, such as thermal desalination, sterilization, evaporative cooling and controlled precipitation. The heat supplied from warm/hot dry bubbles is to vaporize the water in various salt solutions until the solution temperature reaches steady state, which was derived into the energy balance of the BCE. The energy balance and utilization involved in each BCE process form the fundamental theory of these applications. More importantly, it opened a new field for the thermodynamics study in the form of heat and vapor transfer in the bubbles. In this paper, the originally derived energy balance was reviewed on the basis of its physics in the BCE process and compared with new proposed energy balance equations in terms of obtained the enthalpy of vaporization (Δ H vap) values of salt solutions from BCE experiments. Based on the analysis of derivation and Δ H vap values comparison, it is demonstrated that the original balance equation has high accuracy and precision, within 2% over 19-55 °C using improved systems. Also, the experimental and theoretical techniques used for determining Δ H vap values of salt solutions were reviewed for the operation conditions and their accuracies compared to the literature data. The BCE method, as one of the most simple and accurate techniques, offers a novel way to determine Δ H vap values of salt solutions based on its energy balance equation, which had error less than 3%. The thermal energy required to heat the inlet gas, the energy used for water evaporation in the BCE and the energy conserved from water vapor condensation were estimated in an overall energy balance analysis. The good agreement observed between input and potential vapor condensation energy illustrates the efficiency of the BCE system. Typical energy consumption levels for thermal desalination for producing pure water using the BCE process was also analyzed for different inlet air temperatures, and indicated the better energy efficiency, of 7.55 kW·h per m3 of pure water, compared to traditional thermal desalination techniques.

Metal-assisted and microwave accelerated-evaporative crystallization: Application to lysozyme protein

NASA Astrophysics Data System (ADS)

Mauge-Lewis, Kevin

In response to the growing need for new crystallization techniques that afford for rapid processing times along with control over crystal size and distribution, the Aslan Research Group has recently demonstrated the use of Metal-Assisted and Microwave-Accelerated Evaporative Crystallization MA-MAEC technique in conjunction with metal nanoparticles and nanostructures for the crystallization of amino acids and organic small molecules. In this study, we have employed the newly developed MA-MAEC technique to the accelerated crystallization of chicken egg-white lysozyme on circular crystallization platforms in order to demonstrate the proof-of-principle application of the method for protein crystallization. The circular crystallization platforms are constructed in-house from poly (methyl methacrylate) (PMMA) and silver nanoparticle films (SNFs), indium tin oxide (ITO) and iron nano-columns. In this study, we prove the MA-MAEC method to be a more effective technique in the rapid crystallization of macromolecules in comparison to other conventional methods. Furthermore, we demonstrate the use of the novel iCrystal system, which incorporates the use of continuous, low wattage heating to facilitate the rapid crystallization of the lysozyme while still retaining excellent crystal quality. With the incorporation of the iCrystal system, we observe crystallization times that are even shorter than those produced by the MA-MAEC technique using a conventional microwave oven in addition to significantly improved crystal quality.

Role of input angular momentum and target deformation on the incomplete-fusion dynamics in the 16O+154Sm system at ELab=6.1 MeV/nucleon

NASA Astrophysics Data System (ADS)

Singh, D.; Linda, Sneha B.; Giri, Pankaj K.; Mahato, Amritraj; Tripathi, R.; Kumar, Harish; Ansari, M. Afzal; Sathik, N. P. M.; Ali, Rahbar; Kumar, R.; Muralithar, S.; Singh, R. P.

2018-06-01

Spin distributions of nine evaporation residues 164Yb(x n ) , 163Tm(p x n ) , Er,167168(2 p x n ) , Ho-161163(α p x n ) , 164Dy(α 2 p x n ) , and 160Dy(2 α x n ) produced through complete- and incomplete-fusion reactions have been measured in the system 16O+154Sm at projectile energy =6.1 MeV /nucleon using the in-beam charged-particle (Z =1 ,2 )-γ-ray coincidence technique. The results indicate the occurrence of incomplete fusion involving the breakup of 16O into 4He+12C and/or 8Be+8Be followed by fusion of one of the fragments with target nucleus 154Sm. The pattern of measured spin distributions of the evaporation residues produced through complete and incomplete fusion are found to be entirely different from each other. It has been observed from these present results that the mean input angular momentum for the evaporation residues produced through complete fusion is relatively lower than that of evaporation residues produced through incomplete-fusion reactions. The pattern of feeding intensity of evaporation residues populated through complete- and incomplete-fusion reactions has also been studied. The evaporation residues populated through complete-fusion channels are strongly fed over a broad spin range and widely populated, while evaporation residues populated through incomplete-fusion reactions are found to have narrow range feeding only for high spin states. Comparison of present results with earlier data suggests that the value of mean input angular momentum is relatively higher for a deformed target and more mass asymmetric system than that of a spherical target and less mass asymmetric system by using the same projectile and the same energy. Thus, present results indicate that the incomplete-fusion reactions not only depend on the mass asymmetry of the system, but also depend on the deformation of the target.

Toward the Elucidation of the Competing Role of Evaporation and Thermal Decomposition in Ionic Liquids: A Multitechnique Study of the Vaporization Behavior of 1-Butyl-3-methylimidazolium Hexafluorophosphate under Effusion Conditions.

PubMed

Volpe, V; Brunetti, B; Gigli, G; Lapi, A; Vecchio Ciprioti, S; Ciccioli, A

2017-11-16

The evaporation/decomposition behavior of the imidazolium ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BMImPF 6 ) was investigated in the overall temperature range 425-551 K by means of the molecular-effusion-based techniques Knudsen effusion mass loss (KEML) and Knudsen effusion mass spectrometry (KEMS), using effusion orifices of different size (from 0.2 to 3 mm in diameter). Specific effusion fluxes measured by KEML were found to depend markedly on the orifice size, suggesting the occurrence of a kinetically delayed evaporation/decomposition process. KEMS experiments revealed that other species are present in the vapor phase besides the intact ion pair BMImPF 6 (g) produced by the simple evaporation BMImPF 6 (l) = BMImPF 6 (g), with relative abundances depending on the orifice size-the larger the orifice, the larger the contribution of the BMImPF 6 (g) species. By combining KEML and KEMS results, the conclusion is drawn that in the investigated temperature range, when small effusion orifices are used, a significant part of the mass loss/volatility of BMImPF 6 is due to molecular products formed by decomposition/dissociation processes rather than to evaporated intact ion pairs. Additional experiments performed by nonisothermal thermogravimetry-differential thermal analysis (TG-DTA) further support the evidence of simultaneous evaporation/decomposition, although the conventional decomposition temperature derived from TG curves is much higher than the temperatures covered in effusion experiments. Partial pressures of the BMImPF 6 (g) species were derived from KEMS spectra and analyzed by second- and third-law methods giving a value of Δ evap H 298K ° = 145.3 ± 2.9 kJ·mol -1 for the standard evaporation enthalpy of BMImPF 6 . A comparison is done with the behavior of the 1-butyl-3-methylimidazolium bis(trifluoromethyl)sulfonylimide (BMImNTf 2 ) ionic liquid.

A simple technique to reduce evaporation of crystallization droplets by using plate lids with apertures for adding liquids

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

Zipper, Lauren E.; Binghamton University, 4400 Vestal Parkway East, Vestal, NY 13902; Aristide, Xavier

This article describes the use of evaporation control lids that are fitted to crystallization plates to improve the reproducibility of trials using as little as 5 nl. The plate lids contain apertures which are large enough for the transfer of protein containing droplets, but small enough to greatly reduce the rate of evaporation during the time needed to prepare the plate. A method is described for using plate lids to reduce evaporation in low-volume vapor-diffusion crystallization experiments. The plate lids contain apertures through which the protein and precipitants were added to different crystallization microplates (the reservoir was filled before fittingmore » the lids). Plate lids were designed for each of these commonly used crystallization microplates. This system minimizes the dehydration of crystallization droplets containing just a few nanolitres of protein and precipitant, and results in more reproducible diffraction from the crystals. For each lid design, changes in the weight of the plates were used to deduce the rate of evaporation under different conditions of temperature, air movement, droplet size and precipitant. For comparison, the state of dehydration was also visually assessed throughout the experiment. Finally, X-ray diffraction methods were used to compare the diffraction of protein crystals that were conventionally prepared against those that were prepared on plates with plate lids. The measurements revealed that the plate lids reduced the rate of evaporation by 63–82%. Crystals grown in 5 nl drops that were set up with plate lids diffracted to higher resolution than similar crystals from drops that were set up without plate lids. The results demonstrate that plate lids can be instrumental for improving few-nanolitre crystallizations.« less

Improved Detection Technique for Solvent Rinse Cleanliness Verification

NASA Technical Reports Server (NTRS)

Hornung, S. D.; Beeson, H. D.

2001-01-01

The NASA White Sands Test Facility (WSTF) has an ongoing effort to reduce or eliminate usage of cleaning solvents such as CFC-113 and its replacements. These solvents are used in the final clean and cleanliness verification processes for flight and ground support hardware, especially for oxygen systems where organic contaminants can pose an ignition hazard. For the final cleanliness verification in the standard process, the equivalent of one square foot of surface area of parts is rinsed with the solvent, and the final 100 mL of the rinse is captured. The amount of nonvolatile residue (NVR) in the solvent is determined by weight after the evaporation of the solvent. An improved process of sampling this rinse, developed at WSTF, requires evaporation of less than 2 mL of the solvent to make the cleanliness verification. Small amounts of the solvent are evaporated in a clean stainless steel cup, and the cleanliness of the stainless steel cup is measured using a commercially available surface quality monitor. The effectiveness of this new cleanliness verification technique was compared to the accepted NVR sampling procedures. Testing with known contaminants in solution, such as hydraulic fluid, fluorinated lubricants, and cutting and lubricating oils, was performed to establish a correlation between amount in solution and the process response. This report presents the approach and results and discusses the issues in establishing the surface quality monitor-based cleanliness verification.

Analyse de l'interface cuivre/Teflon AF1600 par spectroscopie des photoelectrons rayons x

NASA Astrophysics Data System (ADS)

Popovici, Dan

The speed of electrical signals through the microelectronic multilevel interconnects depends of the delay time R x C. In order to improve the transmission speed of future microdevices, the microelectronics industry requires the use of metals having lower resistivities and insulators having lower permittivities. Copper and fluoropolymers are interesting candidates for the replacement of the presently used Al/polyimide technology. This thesis presents an X-ray photoelectron spectroscopy (XPS) analysis of the Cu/Teflon AF1600 interface, in order to have a better understanding of those interfacial interactions leading to improved adhesion. Several deposition methods, such as evaporation, sputtering and laser-induced chemical deposition were analyzed and compared. X-ray photoelectron spectroscopy (XPS) was used as the primary characterization technique of the different surfaces and interfaces. In the case of evaporation and sputtering, the loss of fluorine and oxygen atoms leads to graphitization and the crosslinking of carbon chains. The extent of damage caused by copper deposition is higher for sputter deposition because of the higher energies of the incidents atoms. This energy (two orders of magnitude higher than the energy involved in the evaporation) is also responsible for the total reaction of Cu with F and C. For the physical depositions (sputtering and evaporation), an angle-resolved XPS diffusion study showed the copper distribution as a function of depth. (i) For sputter deposition, this distribution is uniform. (ii) In the case of evaporation, we computed the concentration profile using the inverse Laplace transform. Several samples, annealed at different temperatures, were used to calculate the diffusion coefficients for the Cu/Teflon AF1600 interface. The study of interactions at the interface between Teflon AF1600 and copper deposited by different metallization techniques permitted us to elucidate some aspects related to the chemistry and structure of the interface. The presence of the strong Cu-C bond may lead to an enhanced adhesion but a pretreatment (plasma RF, X-ray or excimer laser) is necessary to increase the surface concentration of reactive groups. (Abstract shortened by UMI.)

The reversed-flow gas chromatography technique as a tool for the study of the evaporation retardation of SO2 and (CH3)2S from water by soluble surfactants.

PubMed

Sevastos, D; Kotsalos, E; Koliadima, A

2017-02-01

In the present work the evaporation retardation of SO 2 and (CH 3 ) 2 S (=DMS) from water by soluble surfactants was studied by the Reversed-Flow Gas Chromatography (R.F.G.C.) technique. Using suitable mathematical analysis, rate coefficients, k c , for the transfer of SO 2 and DMS from pure or artificial sea water to the atmospheric environment were determined in the presence or the absence of surfactants. The efficiency of the three surfactants used (CTAB, TRITON X-100 and SDS) to retard the evaporation rate of SO 2 and DMS from water was estimated by the decrease of the k c values in the presence of the three surfactants, compared to those in the absence of surfactants. The more efficient surfactant for the retardation evaporation of SO 2 from both the pure and the artificial sea water was found to be the cationic CTAB surfactant, as the maximum decreases of the k c values were found to be 4.61×10 -3 cms -1 (number of films, n=1) and 3.07×10 -3 cms -1 (n=3), respectively. On the other hand, more efficient surfactant for the retardation evaporation of DMS from pure water was found to be the non-ionic TRITON X-100, in which the decrease of the k c value was estimated to be 18.20×10 -3 cms -1 (n=3) and from artificial sea water the cationic CTAB surfactant in which the decrease of the k c value was found to be 8.24×10 -3 cms -1 (n=3). Finally, the precision of the R.F.G.C. method in studying the retardation effect of various surfactants in the transfer of SO 2 and DMS from the water body to the atmosphere is estimated (mean value 96.69%), and the experimental values of k c are compared with those given in the literature. Copyright © 2016 Elsevier B.V. All rights reserved.

Time series of canopy intercepted water and dew observed in a tropical tree plantation by means of microwave radiometry

NASA Astrophysics Data System (ADS)

Schneebeli, M.; Wolf, S.; Kunert, N.; Eugster, W.; Mätzler, C.

2012-04-01

During summer and autumn 2007, a 11 GHz microwave radiometer was deployed in an experimental tree plantation in Sardinilla, Panama. With this instrument, the opacity of the tree canopy was derived from incoming brightness temperatures received on the ground. A collocated eddy-covariance flux tower measured water vapor fluxes and meteorological variables above the canopy. It was found that canopy intercepted rain and dew formation modulated the diurnal opacity cycle. With an enhanced canopy opacity model accounting for water deposited on the leaves, we quantified the influence of canopy stored water (i.e. intercepted water and dew) on the opacity. With this technique it was possible to directly monitor high resolution time series of dew formation and rain interception during a period of two weeks. In contrast to through-fall measurements, this new technique allows to determine the amount of intercepted rain more precisely and during day and night since evaporation effects do not hamper the accuracy of the method. We found that during light rainfall up to 60% of the rain amount is intercepted by the canopy whereas during periods of intense rainfall, only 4% were intercepted. On average, about 15% of the rain amount was intercepted during rainfalls of medium intensities. By comparing the interception with the water vapor flux time series it was found that intercepted water is evaporated rapidly after it is deposited on the leaves, which resulted in an enhanced water vapor flux. Our study also provides the first direct measurements and quantifications of the temporal evolution of dew formation and evaporation in a tree canopy on a diurnal base. Dew accumulated during the night and until about 2 h after sunrise, when the water vapor flux began to exceed the dew formation rate. The dew continued to evaporate for another 3.5 h until the surface of the leaves was completely dry. On average, 0.17 mm of dew was formed during the night. Dew evaporation contributed 5% to the total water vapor flux measured above the canopy.

Supertitrations: High-Precision Methods.

ERIC Educational Resources Information Center

Guenther, W. B.

1988-01-01

Offers challenging work at a higher level of technique than most students meet in elementary laboratory work. Uses a combined weight and volumetric sequence not shown in textbooks. Notes modern rapid balances help lower evaporation loss during weighings. Discusses the balance, weights, and buoyancy considerations. (MVL)

Vacuum ultraviolet coatings of Al protected with MgF(2) prepared both by ion-beam sputtering and by evaporation.

PubMed

Fernández-Perea, Mónica; Larruquert, Juan I; Aznárez, José A; Pons, Alicia; Méndez, José A

2007-08-01

Ion-beam sputtering (IBS) and evaporation are the two deposition techniques that have been used to deposit coatings of Al protected with MgF(2) with high reflectance in the vacuum ultraviolet down to 115 nm. Evaporation deposited (ED) Al protected with IBS MgF(2) resulted in a larger (smaller) reflectance below (above) 125 nm than the well-known all-evaporated coatings. A similar comparison is obtained when the Al film is deposited by IBS instead of evaporation. The lower reflectance of the coatings protected with IBS versus ED MgF(2) above 125 nm is because of larger absorption of the former. Both nonprotected IBS Al, as well as IBS Al protected with ED MgF(2), resulted in a band of reflectance loss that was peaked at 127 and 157 nm, respectively. This result was attributed to the excitation of surface plasmons due to the enhancement of surface roughness with large spatial wave vectors in the sputter deposition. This reflectance loss for IBS Al protected with MgF(2) is small at the short (lambda~120 nm) and long (lambda<350 nm) wavelengths investigated. IBS Al protected with ED MgF(2) is thus a promising coating for these two spectral regions. Coatings protected with IBS MgF(2) resulted in a reflectance as high as coatings protected with ED MgF(2) at wavelengths longer than 550 nm, whereas the former had a lower reflectance below this wavelength.

Visualization of the evaporation of a diesel spray using combined Mie and Rayleigh scattering techniques

NASA Astrophysics Data System (ADS)

Adam, Anne; Leick, Philippe; Bittlinger, Gerd; Schulz, Christof

2009-09-01

Evaporating Diesel sprays are studied by laser Rayleigh scattering measurements in an optically accessible high-pressure/high-temperature cell that reproduces the thermodynamic conditions which exist in the combustion chamber of a Diesel engine during injection. n-Decane is injected into the vessel using a state-of-the-art near-production three-hole nozzle. Global images of the distributions of the liquid and vapor phases of the injected fuel are obtained using a combined Schlieren and Mie scattering setup. More details about the evaporation are revealed when the spray is illuminated by a laser light sheet: laser light can be scattered by molecules in the gas phase (Rayleigh scattering) or comparably large fuel droplets (Mie scattering). The former is seen in regions where the fuel has completely evaporated, and the latter is dominant in regions with high droplet concentrations. Studying the polarization of the signal light allows the distinction of three different regions in the spray that are characterized by a moderate, low or negligible concentration of liquid fuel droplets. The characteristics of fuel evaporation are investigated for different observation times after the start of injection, chamber conditions and injection pressures. For the quantification of the fuel concentration measurements based on Rayleigh scattering, a calibration method that uses propane as a reference gas is presented and tested. At high ambient temperatures, the accuracy of the concentration measurements is limited by pyrolysis of the fuel molecules.

Improved Visualization of Gastrointestinal Slow Wave Propagation Using a Novel Wavefront-Orientation Interpolation Technique.

PubMed

Mayne, Terence P; Paskaranandavadivel, Niranchan; Erickson, Jonathan C; OGrady, Gregory; Cheng, Leo K; Angeli, Timothy R

2018-02-01

High-resolution mapping of gastrointestinal (GI) slow waves is a valuable technique for research and clinical applications. Interpretation of high-resolution GI mapping data relies on animations of slow wave propagation, but current methods remain as rudimentary, pixelated electrode activation animations. This study aimed to develop improved methods of visualizing high-resolution slow wave recordings that increases ease of interpretation. The novel method of "wavefront-orientation" interpolation was created to account for the planar movement of the slow wave wavefront, negate any need for distance calculations, remain robust in atypical wavefronts (i.e., dysrhythmias), and produce an appropriate interpolation boundary. The wavefront-orientation method determines the orthogonal wavefront direction and calculates interpolated values as the mean slow wave activation-time (AT) of the pair of linearly adjacent electrodes along that direction. Stairstep upsampling increased smoothness and clarity. Animation accuracy of 17 human high-resolution slow wave recordings (64-256 electrodes) was verified by visual comparison to the prior method showing a clear improvement in wave smoothness that enabled more accurate interpretation of propagation, as confirmed by an assessment of clinical applicability performed by eight GI clinicians. Quantitatively, the new method produced accurate interpolation values compared to experimental data (mean difference 0.02 ± 0.05 s) and was accurate when applied solely to dysrhythmic data (0.02 ± 0.06 s), both within the error in manual AT marking (mean 0.2 s). Mean interpolation processing time was 6.0 s per wave. These novel methods provide a validated visualization platform that will improve analysis of high-resolution GI mapping in research and clinical translation.

Slow crack growth measurement using an electrical grid

NASA Technical Reports Server (NTRS)

Martin, D. J.; Davido, K. W.; Scott, W. D.

1986-01-01

Photolithography was used to produce a resistance grid on the surface of a DCB fracture specimen. The grid line spacings were 10 microns over a distance of 2 cm. Slow crack growth was measured on soda-lime-silica glass. At low values of K(I) (0.3 to 0.4 MPa.sq r + m, increased. Equations are given for the design of grids. The grid technique could be used to measure very slow crack growth at high temperature with appropriate compatible metal-ceramic materials.

Automated nystagmus analysis. [on-line computer technique for eye data processing

NASA Technical Reports Server (NTRS)

Oman, C. M.; Allum, J. H. J.; Tole, J. R.; Young, L. R.

1973-01-01

Several methods have recently been used for on-line analysis of nystagmus: A digital computer program has been developed to accept sampled records of eye position, detect fast phase components, and output cumulative slow phase position, continuous slow phase velocity, instantaneous fast phase frequency, and other parameters. The slow phase velocity is obtained by differentiation of the calculated cumulative position rather than the original eye movement record. Also, a prototype analog device has been devised which calculates the velocity of the slow phase component during caloric testing. Examples of clinical and research eye movement records analyzed with these devices are shown.

Comparative experimental investigation on the actuation mechanisms of ionic polymer–metal composites with different backbones and water contents

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

Zhu, Zicai; Chang, Longfei; Wang, Yanjie

2014-03-28

Water-based ionic polymer–metal composites (IPMCs) exhibit complex deformation properties, especially when the water content changes. To explore the general actuation mechanisms, both Nafion and Flemion membranes are used as the polymer backbones. IPMC deformation includes three stages: fast anode deformation, relaxation deformation, and slow anode deformation, which is mainly dependent on the water content and the backbone. When the water content decreases from 21 to 14 wt. %, Nafion–IPMC exhibits a large negative relaxation deformation, zero deformation, a positive relaxation deformation, and a positive steady deformation without relaxation in sequence. Despite the slow anode deformation, Flemion–IPMC also shows a slight relaxation deformation,more » which disappears when the water content is less than 13 wt. %. The different water states are investigated at different water contents using nuclear magnetic resonance spectroscopy. The free water, which decreases rapidly at the beginning through evaporation, is proven to be critical for relaxation deformation. For the backbone, indirect evidence from the steady current response is correlated with the slow anode deformation of Flemion-IPMC. The latter is explained by the secondary dissociation of the weak acid group –COOH. Finally, we thoroughly explain not only the three deformations by swelling but also their evolvement with decreasing water content. A fitting model is also presented based on a multi-diffusion equation to reveal the deformation processes more clearly, the results from which are in good agreement with the experimental results.« less

Stable isotope hydrology in fractured and detritic aquifers at both sides of the South Atlantic Ocean: Mar del Plata (Argentina) and the Rawsonville and Sandspruit river catchment areas (South Africa)

NASA Astrophysics Data System (ADS)

Glok Galli, Melisa; Damons, Matthew E.; Siwawa, Sitembiso; Bocanegra, Emilia M.; Nel, Jacobus M.; Mazvimavi, Dominic; Martínez, Daniel E.

2017-01-01

The aim of this work is to characterize the isotope composition of water (2H and 18O) in order to establish the relationship between fractured and detritic aquifers in similar hydrological environments located at both sides of the Atlantic Ocean. The Mar del Plata zone, placed in the Argentine Buenos Aires province in South America, and the Rawsonville and Sandspruit river catchment areas, situated in the Western Cape province in South Africa were compared. Rainwater and groundwater samples from fractured and detritic aquifers were analyzed through laser spectroscopy. In both Argentina and South African study sites, stable isotopes data demonstrate an aquifers recharge source from rainfall. For the Mar del Plata region, two different groups of detritic aquifer's samples with distinct recharge processes can be identified due to the close relationship existing between the present hydrogeological environments, the aquifer's grain size sediments and the isotopes contents: one representing rapid infiltration in aquifer sediments of the creeks' palaeobeds and hills zones (sandy or silt sandy sediments) and the other with slow infiltration of evaporated water in plain zones with an aquitard behavior. In the last group, the evaporation process occurs previous infiltration or in the aquifer's non-saturated zone, because of the existence of very low topographic gradients and fine-grained sediments. The evaporation phenomenon is not evident in the Sandspruit river catchment site's detritic aquifer, because its sandy composition allows a faster infiltration rate than in the loess that compounds the Pampeano aquifer in the interfluves zones of the Argentinian study area.

SPME-GCMS study of the natural attenuation of aviation diesel spilled on the perennial ice cover of Lake Fryxell, Antarctica.

PubMed

Jaraula, Caroline M B; Kenig, Fabien; Doran, Peter T; Priscu, John C; Welch, Kathleen A

2008-12-15

In January 2003, a helicopter crashed on the 5 m thick perennial ice cover of Lake Fryxell (McMurdo Dry Valleys, East Antarctica), spilling approximately 730 l of aviation diesel fuel (JP5-AN8 mixture). The molecular composition of the initial fuel was analyzed by solid phase microextraction (SPME) gas chromatography-mass spectrometry (GC-MS), then compared to the composition of the contaminated ice, water, and sediments collected a year after the spill. Evaporation is the major agent of diesel weathering in meltpool waters and in the ice. This process is facilitated by the light non-aqueous phase liquid properties of the aviation diesel and by the net upward movement of the ice as a result of ablation. In contrast, in sediment-bearing ice, biodegradation by both alkane- and aromatic-degraders was the prominent attenuation mechanism. The composition of the diesel contaminant in the ice was also affected by the differential solubility of its constituents, some ice containing water-washed diesel and some ice containing exclusively relatively soluble low molecular weight aromatic hydrocarbons such as alkylbenzene and naphthalene homologues. The extent of evaporation, water washing and biodegradation between sites and at different depths in the ice are evaluated on the basis of molecular ratios and the results of JP5-AN8 diesel evaporation experiment at 4 degrees C. Immediate spread of the aviation diesel was enhanced where the presence of aeolian sediments induced formations of meltpools. However, in absence of melt pools, slow spreading of the diesel is possible through the porous ice and the ice cover aquifer.

Inhaled corticosteroid metered-dose inhalers: how do variations in technique for solutions versus suspensions affect drug distribution?

PubMed

Robinson, Christie A; Tsourounis, Candy

2013-03-01

To assess the literature that evaluates how variations in metered-dose inhaler (MDI) technique affect lung distribution for inhaled corticosteroids (ICSs) formulated as MDI suspensions and solutions. PubMed (up to November 2012) and Cochrane Library (up to November 2012) were searched using the terms metered-dose inhalers, HFA 134a, Asthma/*drug therapy, and inhaled corticosteroids. In addition, reference citations from publications identified were reviewed. All articles in English from the data sources that assessed MDI technique comparing total lung distribution (TLD) of MDI solutions or suspensions formulated with ICSs were included in the review. Five relevant studies were identified. Five controlled studies compared how variations in MDI technique affect TLD for ICS MDI solutions with suspensions. MDI solutions resulted in greater TLD compared with larger particle MDI suspensions. Delayed or early inspiration upon device actuation of MDI solutions resulted in less TLD than coordinated actuation, but with a 3- to 4-times greater TLD than MDI suspensions inhaled using a standard technique. A sixth study evaluated inspiratory flow rates (IFR) for small, medium, and large particles. Rapid and slow IFRs resulted in similar TLD for small particles, while far fewer particles reached the airways with medium and large particles at rapid, rather than slow, IFRs. Based on the literature evaluated, standard MDI technique should be used for ICS suspensions. ICS MDI solutions can provide a higher average TLD than larger-particle ICS suspensions using standard technique, discoordinated inspiration and medication actuation timing, or rapid and slow IFRs. ICS MDI solutions allow for a more forgiving technique, which makes them uniquely suitable options for patients with asthma who have difficultly with MDI technique.

Is the gas-particle partitioning in alpha-pinene secondary organic aerosol reversible?

NASA Astrophysics Data System (ADS)

Grieshop, Andrew P.; Donahue, Neil M.; Robinson, Allen L.

2007-07-01

This paper discusses the reversibility of gas-particle partitioning in secondary organic aerosol (SOA) formed from α-pinene ozonolysis in a smog chamber. Previously, phase partitioning has been studied quantitatively via SOA production experiments and qualitatively by perturbing temperature and observing particle evaporation. In this work, two methods were used to isothermally dilute the SOA: an external dilution sampler and an in-chamber technique. Dilution caused some evaporation of SOA, but repartitioning took place on a time scale of tens of minutes to hours-consistent with an uptake coefficient on the order of 0.001-0.01. However, given sufficient time, α-pinene SOA repartitions reversibly based on comparisons with data from conventional SOA yield experiments. Further, aerosol mass spectrometer (AMS) data indicate that the composition of SOA varies with partitioning. These results suggest that oligomerization observed in high-concentration laboratory experiments may be a reversible process and underscore the complexity of the kinetics of formation and evaporation of SOA.

Timescales of Land Surface Evapotranspiration Response

NASA Technical Reports Server (NTRS)

Scott, Russell; Entekhabi, Dara; Koster, Randal; Suarez, Max

1997-01-01

Soil and vegetation exert strong control over the evapotranspiration rate, which couples the land surface water and energy balances. A method is presented to quantify the timescale of this surface control using daily general circulation model (GCM) simulation values of evapotranspiration and precipitation. By equating the time history of evaporation efficiency (ratio of actual to potential evapotranspiration) to the convolution of precipitation and a unit kernel (temporal weighting function), response functions are generated that can be used to characterize the timescales of evapotranspiration response for the land surface model (LSM) component of GCMS. The technique is applied to the output of two multiyear simulations of a GCM, one using a Surface-Vegetation-Atmosphere-Transfer (SVAT) scheme and the other a Bucket LSM. The derived response functions show that the Bucket LSM's response is significantly slower than that of the SVAT across the globe. The analysis also shows how the timescales of interception reservoir evaporation, bare soil evaporation, and vegetation transpiration differ within the SVAT LSM.

Preparation of Mirror Coatings for the Vacuum Ultraviolet in a 2-m Evaporator.

PubMed

Bradford, A P; Hass, G; Osantowski, J F; Toft, A R

1969-06-01

The design and features of a 2-m evaporator suitable for coating large mirrors uniformly with Al + MgF(2) and Al + LiF films of high reflectance in the vacuum uv are described. The techniques used for monitoring film thicknesses during the film deposition and for producing films of uniform thicknesses over large areas are discussed. It is shown that the Al films for MgF(2)_ and LiF-protected mirrors of highest reflectance in the vacuum uv down to 1000 A should be 700-800 A thick. Data on the vacuum uv reflectance of Al coated with MgF(2) films of various thicknesses are presented. It was found that mirror coatings prepared in a large evaporator have a higher reflectance in the vacuum uv than those deposited under the same vacuum and deposition conditions in a small vacuum unit. At lambda = 1216 A, the reflectance of Al overcoated with 250 A of MgF(2) was measured to be about 85%.

Purification of ^4He through Differential Evaporation

NASA Astrophysics Data System (ADS)

Dubose, F.; Haase, D. G.; Huffman, P. R.

2008-10-01

The neutron electric dipole moment (nEDM) experiment, to be housed at the Spallation Neutron Source at Oak Ridge National Laboratories, will probe for a dipole moment at the level of 10-28 e cm. As part of the measurement process, neutrons precess in an environment of isotopically pure helium, doped with polarized ^3He. After this ^3He depolarizes it must be removed. We are developing an evaporative purification technique for this removal, lowering the concentration of ^3He in ^4He from 10-8 to 10-10, at an operating temperature of 300 -- 350 mK. Because the vapor pressure of ^3He is enhanced at temperatures below 500mK, ^3He atoms can be preferentially removed from the solution. The purifier requires a large liquid surface area, while minimizing superfluid film flow. The evaporated atoms are adsorbed on activated charcoal. We have built a device to measure ^3He/^4He ratios using a leak detector mass spectrometer and a residual gas analyzer.