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1
Kleppe, A. K., and A. P. Jephcoat. "High-pressure Raman spectroscopic studies of FeS2 pyrite." Mineralogical Magazine 68, no. 3 (June 2004): 433–41. http://dx.doi.org/10.1180/0026461046830196.
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AbstractWe report micro-Raman spectroscopic studies of FeS2 pyrite in the diamond-anvil cell under hydrostatic and non-hydrostatic conditions to 55 GPa at room temperature. Four out of five Ramanactive modes are resolved with helium as a pressure-transmitting medium to highest pressures. The fifth mode, Tg(2) [377 cm-1], is weak and unresolved lying ∼2 cm-1 from the intense Ag mode [379 cm-1] at 1 bar. We observe an increase in the separation of the Eg [344 cm-1] and Tg(1) [350 cm-1] modes under compression. All observed frequencies increase continuously with increasing pressure showing no evidence for a structural phase transition in accord with both X-ray diffraction and shock-wave studies. The Ag and Tg(1) modes gain significantly in intensity relative to the Eg mode with increasing pressure probably resulting from Raman resonance effects. The Tg(3) mode [430 cm-1] broadens unusually compared to the other pyrite modes with pressure. The Raman data are consistent with a contraction of the S-S and Fe-S bonds under pressure. The main effect of non-hydrostatic conditions on the Raman modes is a strong pressure-induced broadening; the pressure-dependence of the frequencies and relative intensities are not affected within the error of the measurements.
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Saitou, Yoshifumi. "Spontaneously excited longitudinal backward waves in dusty plasmas." Physics of Plasmas 30, no. 1 (January 2023): 013701. http://dx.doi.org/10.1063/5.0119660.
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A spontaneously excited longitudinal backward dust wave was experimentally examined. Dust particles were confined in a vertical glass cylinder. The spontaneously excited wave propagated downward. A dispersion relation was obtained by measuring the wavenumber and phase velocity. The dispersion relation showed that the wave consisted of two different modes, including a backward wave. The Trivelpiece–Gould (TG) mode was invoked as a dispersion relation to explain the backward wave, although the cyclotron angular frequency, [Formula: see text], appearing in the TG mode was replaced with [Formula: see text], where [Formula: see text] is the dust angular frequency. The experimental results were compared with the calculated dispersion relation, including the TG mode. The group velocity of the spontaneously excited backward wave is larger than the value predicted with the TG mode. It is necessary to explain the backward wave to modify the TG mode model or to construct a new model.
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Tassinari, Roberta, Alessia Tammaro, Gabriele Lori, Sabrina Tait, Andrea Martinelli, Luigia Cancemi, Paolo Frassanito, and Francesca Maranghi. "Risk Assessment of Transgender People: Development of Rodent Models Mimicking Gender-Affirming Hormone Therapies and Identification of Sex-Dimorphic Liver Genes as Novel Biomarkers of Sex Transition." Cells 12, no. 3 (February 1, 2023): 474. http://dx.doi.org/10.3390/cells12030474.
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Transgender (TG) describes individuals whose gender identity differs from the social norms. TG people undergoing gender-affirming hormone therapy (HT) may be considered a sub-group of the population susceptible to environmental contaminants for their targets and modes of action. The aim of this study is to set appropriate HT doses and identify specific biomarkers to implement TG animal models. Four adult rats/group/sex were subcutaneously exposed to three doses of HT (plus control) selected starting from available data. The demasculinizing-feminizing models (dMF) were β-estradiol plus cyproterone acetate, at 0.09 + 0.33, 0.09 + 0.93 and 0.18 + 0.33 mg, respectively, five times/week. The defeminizing-masculinizing models (dFM) were testosterone (T) at 0.45, 0.95 and 2.05 mg, two times/week. Clitoral gain and sperm count, histopathological analysis of reproductive organs and liver, hormone serum levels and gene expression of sex-dimorphic CYP450 were evaluated. In the dMF model, the selected doses—leading to T serum levels at the range of the corresponding cisgender—induced strong general toxicity and cannot be used in long-term studies. In the dFM model, 0.45 mg of T represents the correct dose. In addition, the endpoints selected are considered suitable and reliable to implement the animal model. The sex-specific CYP expression is a suitable biomarker to set proper (de)masculinizing/(de)feminizing HT and to implement TG animal models.
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Togun, Necla, and Süleyman M. Bağdatli. "The vibration of nanobeam resting on elastic foundation using modified couple stress theory." Tehnički glasnik 12, no. 4 (December 4, 2018): 221–25. http://dx.doi.org/10.31803/tg-20180214212115.
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In this paper, the vibration of nanobeams resting on the Winkler foundation is proposed using the modified couple stress theory. Hamilton’s principle is utilized to construct the governing equations. The size effect of the nanobeam cannot be captured by using classical Euler-Bernoulli beam theory, but the modified couple stress theory model can capture it because it includes material length scale parameter that a newly developed model has. Once the material length scale parameter is assumed to be zero, the classical Euler-Bernoulli beam theory equation is obtained. Multiple scale method is employed to obtain the result. Simply supported boundary condition is used to study natural frequencies. The influence of material length scale parameter and the Winkler elastic foundation parameter on the fundamental frequencies of the nanobeam is investigated and tabulated. Also, in the present study, Poisson’s ratio is taken as constant. Nanobeam resting on the Winkler foundation which is simply supported is analyzed to illustrate the size effects on the free vibration. Numerical results for the simply supported nanobeam indicate that the first fundamental frequency calculated by the presented model is higher than the classical one. Moreover, it is obtained that the size influence is more substantial for higher vibration modes. The results indicate that the significant importance of the size influences the analysis of nanobeams. The vibration of nanobeam exhibits a hardening spring behavior, and the newly developed models are the beams stiffer than according to the classical beam theory. Modified couple stress theory tends to be more helpful in describing the size-dependent mechanical properties of nanoelectromechanical systems (NEMS).
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Karp, Michael, and Jacob Cohen. "On the secondary instabilities of transient growth in Couette flow." Journal of Fluid Mechanics 813 (January 20, 2017): 528–57. http://dx.doi.org/10.1017/jfm.2016.874.
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The secondary instability of linear transient growth (TG) in Couette flow is explored theoretically, utilizing an analytical representation of the TG based on four modes and their nonlinear interactions. The evolution of the secondary disturbance is derived using the multiple time scales method. The theoretical predictions are compared with direct numerical simulations and very good agreement with respect to the growth of the disturbance energy and associated vortical structures is observed, up to the final stage just before the breakdown to turbulence. The theoretical model enables us to perform a full parametric study, including TG symmetry type, various wavenumbers, initial energy, TG nonlinearity and Reynolds number, to find all possible routes to transition and the optimal parameters for each type of the secondary disturbance. It is found that the most dangerous secondary disturbances are associated with spanwise wavenumbers which generate the strongest inflection points, i.e. those having maximal shear, rather than with those maximizing the energy gain during the TG phase.
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Sharma, A. K., and S. Konar. "Anisotropic self-defocusing of a Trivelpiece-Gould mode in a plasma." Journal of Plasma Physics 52, no. 2 (October 1994): 189–93. http://dx.doi.org/10.1017/s0022377800017852.
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The paper presents a paraxial-ray theory of self-defocusing of obliquely propagating Trivelpiece-Gould (TG) modes in a homogeneous plasma. The TG mode with Gaussian distribution of intensity, in a direction perpendicular to its phase velocity, creates a ponderomotive force on electrons. The electrons are redistributed through ambipolar diffusion. The redistributed electrons are responsible for defocusing of the TG mode. The importance of our study is pointed out.
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CORBERI, F., and A. CONIGLIO. "LACK OF EQUILIBRATION IN A MODEL FOR CONTINUOUSLY SUPERCOOLED LIQUIDS." Fractals 11, supp01 (February 2003): 109–18. http://dx.doi.org/10.1142/s0218348x0300177x.
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We consider the dynamics of supercooled fluids subject to a continuous quenching procedure, with cooling rate r = dT(t)/dt. The analysis is carried out analytically in the framework of a mean field schematic model recently introduced.1 We show the existence of a glass temperature Tg(r) below which the system falls out of equilibrium. Tg(r) approaches logarithmically in r the ideal glass temperature T0 = lim r→0Tg(r), where the relaxation time diverges á la Vogel-Fulcher, similarly to some experimental observations. Well above Tg(r) a simple fluid behavior is observed. As Tg is approached from above a characteristic wave vector kd divides an high momenta equilibrated region, where a fluid-like behavior is obeyed, from the non thermalized modes with k < kd, for which time translational invariance lacks. Below Tg the system is found in a globally off-equilibrium glassy state characterized by a logarithmic decay of the density fluctuations and aging. The two time correlator decays as an enhanced power law.
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Stier, P., J. Feichter, S. Kinne, S. Kloster, E. Vignati, J. Wilson, L. Ganzeveld, et al. "The aerosol-climate model ECHAM5-HAM." Atmospheric Chemistry and Physics Discussions 4, no. 5 (September 22, 2004): 5551–623. http://dx.doi.org/10.5194/acpd-4-5551-2004.
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Abstract. The aerosol-climate modelling system ECHAM5-HAM is introduced. It is based on a flexible microphysical approach and, as the number of externally imposed parameters is minimised, allows the application in a wide range of climate regimes. ECHAM5-HAM predicts the evolution of an ensemble of microphysically interacting internally- and externally-mixed aerosol populations as well as their size-distribution and composition. The size-distribution is represented by a superposition of log-normal modes. In the current setup, the major global aerosol compounds sulfate (SU), black carbon (BC), particulate organic matter (POM), sea salt (SS), and mineral dust (DU) are included. The simulated global annual mean aerosol burdens (lifetimes) for the year 2000 are for SO4: 0.80 Tg(S) (3.9 days), for BC: 0.11 Tg (5.4 days), for POM: 0.99 Tg (5.4 days), for SS: 10.5 Tg (0.8 days), and for DU: 8.28 Tg (4.6 days). An extensive evaluation with in-situ and remote sensing measurements underscores that the model results are generally in good agreement with observations of the global aerosol system. The simulated global annual mean aerosol optical depth (AOD) is with 0.14 in excellent agreement with an estimate derived from AERONET measurements (0.14) and a composite derived from MODIS-MISR satellite retrievals (0.16). Regionally, the deviations are not negligible. However, the main patterns of AOD attributable to anthropogenic activity are reproduced.
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Stier, P., J. Feichter, S. Kinne, S. Kloster, E. Vignati, J. Wilson, L. Ganzeveld, et al. "The aerosol-climate model ECHAM5-HAM." Atmospheric Chemistry and Physics 5, no. 4 (March 31, 2005): 1125–56. http://dx.doi.org/10.5194/acp-5-1125-2005.
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Abstract. The aerosol-climate modelling system ECHAM5-HAM is introduced. It is based on a flexible microphysical approach and, as the number of externally imposed parameters is minimised, allows the application in a wide range of climate regimes. ECHAM5-HAM predicts the evolution of an ensemble of microphysically interacting internally- and externally-mixed aerosol populations as well as their size-distribution and composition. The size-distribution is represented by a superposition of log-normal modes. In the current setup, the major global aerosol compounds sulfate (SU), black carbon (BC), particulate organic matter (POM), sea salt (SS), and mineral dust (DU) are included. The simulated global annual mean aerosol burdens (lifetimes) for the year 2000 are for SU: 0.80 Tg(S) (3.9 days), for BC: 0.11 Tg (5.4 days), for POM: 0.99 Tg (5.4 days), for SS: 10.5 Tg (0.8 days), and for DU: 8.28 Tg (4.6 days). An extensive evaluation with in-situ and remote sensing measurements underscores that the model results are generally in good agreement with observations of the global aerosol system. The simulated global annual mean aerosol optical depth (AOD) is with 0.14 in excellent agreement with an estimate derived from AERONET measurements (0.14) and a composite derived from MODIS-MISR satellite retrievals (0.16). Regionally, the deviations are not negligible. However, the main patterns of AOD attributable to anthropogenic activity are reproduced.
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Yuan, Xueyin, and Haifei Zheng. "In situ Raman spectroscopic studies of FeS2 pyrite up to 675 K and 2100 MPa using a hydrothermal diamond anvil cell." Mineralogical Magazine 79, no. 1 (February 2015): 1–10. http://dx.doi.org/10.1180/minmag.2015.079.1.01.
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AbstractRaman scattering experiments of natural FeS2 pyrite were performed at simultaneous high-pressure and high-temperature conditions up to 675 K and 2100 MPa using a hydrothermal diamond anvil cell combined with micro-Raman spectroscopy. Four out of five Raman active modes [Eg, Ag, Tg(1) and Tg(3)] were resolved at ambient conditions, the remaining Tg(2) [∼377 cm–1] mode was weak and unresolved occurring ∼2 cm–1 from the intense Ag [379 cm–1] mode. The frequency shifts of the Eg [343 cm–1] and Ag [379 cm–1] modes were determined to be quadratic functions of pressure and temperature: ν343 = 343.35 – 0.0178 × ΔT – 8.4E – 6 × (ΔT)2 + 0.00367 × Δp 3.7E–7 × (Δp)2 + 1.0E–6 × ΔT × Δp and ν379 = 379.35 – 0.0295 × ΔT – 9.0E–6 × (ΔT)2 + 0.00460 × Δp – 5.3E–7 × (Δp)2 + 7.0E–7 × ΔT × Δp. The positive pressure dependence of both modes indicates stress-induced contraction of S–S and Fe–S bonds, whereas the negative temperature dependence shows temperature-induced expansion of them. The Raman spectra of pyrite were used to derive its bulk modulus at high temperatures, thermal expansion coefficient at high pressures and anharmonic parameters at high-pressure and high-temperature conditions.
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Welsch, Frank. "Routes and Modes of Administration of Resorcinol and Their Relationship to Potential Manifestations of Thyroid Gland Toxicity in Animals and Man." International Journal of Toxicology 27, no. 1 (January 2008): 59–63. http://dx.doi.org/10.1080/10915810701876687.
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Medical case reports published in the 20th century over the course of several decades show that resorcinol caused reversible adverse effects on the human thyroid gland (TG) manifested as hypothyroidism. Affected patients had ulcerating leg varicosities and underwent prolonged treatment with ointments containing high concentrations of resorcinol. In animal studies resorcinol failed to induce TG toxicity, unless pharmacokinetic/toxicokinetic (PK/TK) conditions were manipulated (e.g., injection of resorcinol in oil or application in a slow release formulation). A recently completed two-generation reproductive toxicity study in rats did not detect any adverse effects on either reproductive or TG end points ( Welsch, Nemec, and Lawrence, 2008 , Int. J. Toxicol. 37, this issue). Resorcinol intake via drinking water up to the palatability limit had resulted in average daily intakes (mg/kg) of 233 in F0 and F1 males and 304 (premating/gestation) or 660 (lactation) in females. Free resorcinol in blood plasma was barely detectable in a few parental animals, indicating rapid metabolism. This short review communication offers a perspective on compromised human skin barrier function as a likely cause of drastic increases in resorcinol absorption. In conjunction with multiple daily applications over many months to hyperemic, inflamed, and lesioned human skin much higher absorption was likely responsible for the reported human TG toxicity.
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Keleş, Abdullah Emre, and Gökhan Güngör. "Overview of Environmental Problems Caused by Logistics Transportation." Tehnički glasnik 15, no. 4 (November 1, 2021): 569–73. http://dx.doi.org/10.31803/tg-20190308110830.
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Logistic transportation works is considered the main pollutant for the environment, with over 25 per cent CO2 emissions in the EU. This situation has raised concerns for the EU and governments to find solutions and impose regulations to diminish the environmental impact. The purpose of this paper is to investigate two questions regarding environmental issues connected to transportation; “What are the recent trends for establishing sustainable logistics for different transportation methods?” “Which alternatives can be incentivized to decrease the environmental impact of transportation activities?” These projects among the most noteworthy environmental benefits, which are also the case studies of this research are The Viking Concept, The WestMed Bridge, Scandinavian Shuttle and Baxter Inland Sea Transport. The result highlighted in this research is that shifting transportation modes has been successfully implemented, with considerable positive outcomes in terms of environment impact, cost and lead times in several European Union funded projects.
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Timmons, R., and K. De’Bell. "The role of long relaxation times in a simple model with massless modes." Canadian Journal of Physics 96, no. 8 (August 2018): 912–18. http://dx.doi.org/10.1139/cjp-2017-0620.
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The next-nearest-neighbour Ising model with competing nearest-neighbour (nn) and next-nearest-neighbour (nnn) interactions, provides an example of a system in which massless modes destroy order at any finite temperature. This occurs only at a critical ratio, Kc, of the nnn and nn interactions. In this paper we investigate the role of long relaxation times in determining the behaviour of the system when the ratio of the nnn and nn interactions, K, is at and close to this critical ratio. Despite the absence of an order–disorder transition in systems with K = Kc, in Monte Carlo simulations reported here the temperature-dependent behaviour of the relaxation times indicates the existence of a glass transition with a glass transition temperature of Tg ≈ 0.26 in a model with nn interaction J = kB = 1.
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Mansour, Ezzat Abdulaziz. "Big Data Analytics Changes in Health Care Industry." Tehnički glasnik 16, no. 2 (May 11, 2022): 182–86. http://dx.doi.org/10.31803/tg-20220124132449.
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The present research is to find out the information, which are related with big data analytics in health care industry. It enhances the electronic health and electronic medical records in hospitals. Many medical services are experiencing a drastic change in maintaining the medical records in health care industry. Big data analytics is the primary factor that combines many bits of information together to focus on maintaining medical records in a systematic manner. A proper practice of documentation helps and assists the medical procedure easier. There is always a life cycle in maintaining medical records in the health care industry. The study covers the changes that are been implemented and changed the methods of maintain health care records in the private hospitals. Big data analytics is facing many challenges in enhancing the utilization of big information in a simple manner. The investigation contributes on advanced wellbeing rehearses by investigating the appropriate adaption of scientific instruments to EHRs to shape the significant utilization of large information examination with EHRs. The majority of hospitals suffer from inefficient service of big data analytics with electronic health records (EHRs) to develop highquality understandings for their clinical preparations. Marking on the knowledge-based perspective and massive data lifecycle, this article attempt to explore how the three knowledge modes are able to attain consequential usage of huge data analytics with EHRs. To experiment with the offered model, we analyzed five hundred and eighty Chinese nurses of a big hospital over the year 2019. Structural equation modeling was utilized to investigate connections between the meaningful use of EHRs and the knowledge mode of EHRs. The study's outcomes reveal that know-what regarding EHRs use, know-how EHRs storage and utilization, and know-why storage and utilization is able to enhance nurses’ meaningful use of big data analytics with EHRs.
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Peng, Y., K. von Salzen, and J. Li. "Simulation of mineral dust aerosol with Piecewise Log-normal Approximation (PLA) in CanAM4-PAM." Atmospheric Chemistry and Physics 12, no. 15 (August 1, 2012): 6891–914. http://dx.doi.org/10.5194/acp-12-6891-2012.
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Abstract. A new size-resolved dust scheme based on the numerical method of piecewise log-normal approximation (PLA) was developed and implemented in the fourth generation of the Canadian Atmospheric Global Climate Model with the PLA Aerosol Model (CanAM4-PAM). The total simulated annual global dust emission is 2500 Tg yr−1, and the dust mass load is 19.3 Tg for year 2000. Both are consistent with estimates from other models. Results from simulations are compared with multiple surface measurements near and away from dust source regions, validating the generation, transport and deposition of dust in the model. Most discrepancies between model results and surface measurements are due to unresolved aerosol processes. Biases in long-range transport are also contributing. Radiative properties of dust aerosol are derived from approximated parameters in two size modes using Mie theory. The simulated aerosol optical depth (AOD) is compared with satellite and surface remote sensing measurements and shows general agreement in terms of the dust distribution around sources. The model yields a dust AOD of 0.042 and dust aerosol direct radiative forcing (ADRF) of −1.24 W m−2 respectively, which show good consistency with model estimates from other studies.
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Hosseini Sarjou, Parviz. "Towards the Analysis of Reliability Index of Steel Frame Equipped with TADAS Yield Damper." Tehnički glasnik 17, no. 1 (February 1, 2023): 75–80. http://dx.doi.org/10.31803/tg-20220704080217.
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During an earthquake, a considerable amount of kinetic energy from the ground acts as a lateral force on the structure, and this energy causes damage to the main components of the structure, including beams, columns and joints. To reduce the effects of earthquakes on the structure, one of the best methods is dissipation of the energy applied. For this purpose, there are various methods, one of the most practical of which is dampers. Dampers are attachments to a structure that dissipate energy and reduce damage to structural components. The present study examined the TADAS yield damper (Triangular Added Damping and Stiffness) and reliability of the structure equipped with this type of damper (particularly the reliability index) considering the uncertainty in ground motion (ground acceleration) and duration of earthquake. To achieve the objectives of the study, reliability index of the structure was calculated and compared in two modes, steel frame with damper and steel frame without damper, based on criterion of failure and drift and base shear. The results show that dampers dissipate energy from the earthquake and improve reliability and, consequently, reduce failure risk.
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Zhang, Nuozi, Chenhong Wang, Hao Chen, Jiaen Wu, Charles C. Han, and Shanshan Xu. "Electrospun Fibrous Membrane with Confined Chain Configuration: Dynamic Relaxation and Glass Transition." Polymers 14, no. 5 (February 26, 2022): 939. http://dx.doi.org/10.3390/polym14050939.
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Thermodynamic glass transition processes of electrospun membranes were first introduced to study their dynamic relaxation nature, which is not constantly in equilibrium. The relaxation modes of electrospun membranes are slow but measurable near and above the Tg, given the stretched chain over long distances. Based on differential scanning calorimetry (DSC) experiments and the general principle of mode-coupling theory (MCT), endothermic peak temperature and relaxation enthalpy were used to analyze the relaxation process by capturing these instantaneous “arrested” structures. The short- and long-wavelength relaxation modes could be identified with different annealing times and temperatures relative to DSC-measured Tg for electrospun membranes with different molecular weights. Results clearly showed the dynamic nature of a glass transition in polymeric materials. Tp and enthalpy loss initially increased and then directly decreased with the increase in annealing time. When Ta > Tg, regardless of the size of the molecular weight, the Tp and enthalpy loss of the PLGA fibers would directly decrease, and the curves would shift toward the melted one. Combination of electrospinningand normal DSC instrument can be used to investigating the dynamic relax process through an adequately designed kinetic scanning procedure. This result can be explained by the general principle of MCT-type dynamic theory.
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Dzitko, Katarzyna, Barbara Kaproń, Agata Paneth, Adrian Bekier, Tomasz Plech, Piotr Paneth, and Nazar Trotsko. "TZD-Based Hybrid Molecules Act as Dual Anti-Mycobacterium tuberculosis and Anti-Toxoplasma gondii Agents." International Journal of Molecular Sciences 24, no. 3 (January 20, 2023): 2069. http://dx.doi.org/10.3390/ijms24032069.
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Two distinct intracellular pathogens, namely Mycobacterium tuberculosis (Mtb) and Toxoplasma gondii (Tg), cause major public health problems worldwide. In addition, serious and challenging health problems of co-infections of Tg with Mtb have been recorded, especially in developing countries. Due to this fact, as well as the frequent cases of resistance to the current drugs, novel anti-infectious therapeutics, especially those with dual (anti-Tg and anti-Mtb) modes of action, are needed. To address this issue, we explored the anti-Tg potential of thiazolidinedione-based (TZD-based) hybrid molecules with proven anti-Mtb potency. Several TZD hybrids with pyridine-4-carbohydrazone (PCH) or thiosemicarbazone (TSC) structural scaffolds were more effective and more selective than sulfadiazine (SDZ) and trimethoprim (TRI). Furthermore, all of these molecules were more selective than pyrimethamine (PYR). Further studies for the most potent TZD-TSC hybrids 7, 8 and 10 and TZD-PCH hybrid molecule 2 proved that these compounds are non-cytotoxic, non-genotoxic and non-hemolytic. Moreover, they could cross the blood–brain barrier (BBB), which is a critical factor linked with ideal anti-Tg drug development. Finally, since a possible link between Tg infection and the risk of glioblastoma has recently been reported, the cytotoxic potential of TZD hybrids against human glioblastoma cells was also evaluated. TZD-PCH hybrid molecule 2 was found to be the most effective, with an IC50 of 19.36 ± 1.13 µg/mL against T98G cells.
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Gutierrez, Edgar, and Lanping Amy Sung. "Role of Mechanical Stress on the Transglutaminase -Mediated Crosslinking of Erythrocyte Membrane Proteins." Blood 104, no. 11 (November 16, 2004): 1588. http://dx.doi.org/10.1182/blood.v104.11.1588.1588.
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Abstract The life-span of erythrocytes is relatively constant within species and it may be determine by the number of times the cell passes through the circulatory system — enduring repeated cycles of mechanical stress. The intrinsic transglutaminase is the major enzyme capable of catalyzing covalent γ-glutamyl-ε-lysine crosslinks that enhance erythrocyte membrane rigidity. Here we report the cloning of mouse erythrocyte transglutaminase (TG) and the role of mechanical stress on the TG-mediated crosslinking of erythrocyte membrane proteins. TG was PCR cloned from reticulocyte cDNA by using consensus primers. Northern blot analysis of the polyA+ mRNA revealed the TG transcript to be 4.6 kb. Recombinant TG was expressed in yeast and the enzymatic crosslinking was detected by labeling glutamine (Q) acyl-donors in inside out vesicles (IOVs) with fluorescent dansylcadaverine (DNC), which serves as the acyl-acceptor. Crosslinking of spectrin/ankyrin, protein 4.1, and band 3 regions (known Q-donors) by TG required CaCl2 at 0.1–0.25 mM and was regulated by both GTP (optimal at 0.01–0.05 mM) and ATP (optimal at 0.5–2.0 mM) with inhibitory effects at higher concentrations. Protein 4.2 (P4.2), a TG pseudo-enzyme, and the cytoplasmic domain of band 3 (cdb3) were also produced recombinantly which allowed for an in-vitro model to test molecular interactions with TG. Specifically, the crosslinking of cdb3 by TG and the binding of P4.2 and TG to cdb3 were examined. A rise in [CaCl2] to near 1 mM showed increased activity of TG (~75% of maximal activity) together with a slight decrease in TG binding affinity to cdb3 (~25% decrease). The crosslinking of cdb3 by TG was inhibited by P4.2, however the presence of P4.2 facilitated the binding of TG to cdb3. The analysis of endogenous TG activity in intact erythrocytes subjected to mechanical stress by hypo-osmolarity (equi-biaxial stretch) or shear stress (anisotropic extension) was also performed. Hypo-osmotically stressed DNC-loaded erythrocytes in the presence of 2 mM [CaCl2] produced a profile with a less intense crosslinking as compared to that of IOVs. In addition, two novel Q-donors (Q1 and Q2) that required mechanical deformation of the membrane to be crosslinked were discovered. Mechanical shearing of erythrocytes in a viscometer produced a similar profile, again with Q2 being the most crosslinked Q-donor. The ratio of Q2/band 3 crosslinking under shear, however, was two fold greater than that under hypo-osmotically induced stress, indicating that varying degrees of crosslinking may be induced by different modes of mechanical stress. Interestingly, Q2 also became crosslinked in IOVs prepared from erythrocytes previously hyposmotically incubated in the presence of extracellular calcium. The importance of mechanical deformation and calcium influx in the binding of Q2 to membrane-associated proteins was further supported by the findings that calcium introduced into erythrocytes using ionophore A23187 alone was not sufficient to induce the crosslinking of Q2. Together these experiments support our hypothesis that periodic mechanical stress may serve as an inherent molecular timer. It is likely that the activation of TG by transient increases in near-membrane calcium concentrations may lead to the accumulation of crosslinks of proteins at the membrane and an eventual entrapment of less deformable erythrocytes in the sinusoids in the spleen followed by subsequent phagocytosis through the recognition of band 3 auto-antibodies.
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Rees, Tim, and Adam Monahan. "A General Numerical Method for Analyzing the Linear Stability of Stratified Parallel Shear Flows." Journal of Atmospheric and Oceanic Technology 31, no. 12 (December 1, 2014): 2795–808. http://dx.doi.org/10.1175/jtech-d-14-00034.1.
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Abstract The stability analysis of stratified parallel shear flows is fundamental to investigations of the onset of turbulence in atmospheric and oceanic datasets. The stability analysis is performed by considering the behavior of small-amplitude waves, which is governed by the Taylor–Goldstein (TG) equation. The TG equation is a singular second-order eigenvalue problem, whose solutions, for all but the simplest background stratification and shear profiles, must be computed numerically. Accurate numerical solutions require that particular care be taken in the vicinity of critical layers resulting from the singular nature of the equation. Here a numerical method is presented for finding unstable modes of the TG equation, which calculates eigenvalues by combining numerical solutions with analytical approximations across critical layers. The accuracy of this method is assessed by comparison to the small number of stratification and shear profiles for which analytical solutions exist. New stability results from perturbations to some of these profiles are also obtained.
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Jaiman, N. K., and V. K. Tripathi. "Parametric upconversion of TM and Trivelpiece-Gould (TG) modes to high frequency free electron laser (FEL)." Radiophysics and Quantum Electronics 37, no. 6 (June 1994): 484–88. http://dx.doi.org/10.1007/bf01088661.
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Wang, Jianxin, and David B. Wolff. "Evaluation of TRMM Rain Estimates Using Ground Measurements over Central Florida." Journal of Applied Meteorology and Climatology 51, no. 5 (May 2012): 926–40. http://dx.doi.org/10.1175/jamc-d-11-080.1.
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AbstractThis study evaluates space-based rain estimates from the Tropical Rainfall Measuring Mission (TRMM) satellite using ground-based measurements from the radar (GR) and tipping-bucket rain gauges (TG) over the TRMM Ground Validation (GV) site at Melbourne, Florida. The satellite rain products are derived from the TRMM Microwave Imager (TMI), precipitation radar (PR), and combined (COM) rain algorithms using observations from both instruments. The TRMM satellite and GV rain products are spatiotemporally matched and are intercompared at multiple time scales over the 12-yr period from 1998 to 2009. On monthly and yearly scales, the TG agree excellently with the GR because the GR rain rates are generated using the TG data as a constraint on a monthly basis. However, large disagreements exist between the GR and TG at shorter time scales because of their significantly different spatial and temporal sampling modes. The yearly biases relative to the GR for the PR and TMI are generally negative, with a few exceptions. The COM bias fluctuates from year to year over the 12-yr period. The PR, TMI, and COM are in good overall agreement with the GR in the lower range of rain rates, but the agreement is notably worse at higher rain rates. The diurnal cycle of rainfall is captured well by all products, but the peak satellite-derived rainfall (PR, TMI, and COM) lags the peak from the ground measurements (GR and TG) by ~1 h.
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Wu, Xue Bang, Hua Guang Wang, Chang Song Liu, and Zhen Gang Zhu. "Mechanical Relaxation Studies of Sub-Rouse Modes in Amorphous Polymers." Solid State Phenomena 184 (January 2012): 52–59. http://dx.doi.org/10.4028/www.scientific.net/ssp.184.52.
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Mechanical spectroscopy is a powerful tool for the investigation of molecular dynamics of amorphous polymers over a large temperature range and frequency scale. In this work, by using high precision shear mechanical spectroscopy tool, we have investigated the segmental dynamics from local segmental relaxation to sub-Rouse modes in a series of amorphous polymers. We have demonstrated the existence of sub-Rouse modes slower than the local segmental motion in amorphous polymers. The sub-Rouse modes exhibit a similar change of dynamics at the same temperature TB ~1.2 Tg, as the local segmental relaxation through the temperature dependence of relaxation time and relaxation strength. Furthermore, the crossover relaxation time of the sub-Rouse modes at TB is almost the same for all the polymers investigated, i.e. τα'(TB) = 10-1±0.5 s, which is independent of molecular weight and molecular structure. This remarkable finding indicates that solely the time scale of the relaxation determines the change in dynamics of the sub-Rouse modes. According to the coupling model, the crossover is suggested to be caused by the onset of strong intermolecular cooperativity below TB. Hence the results suggest that the sub-Rouse modes and their properties are generally found in amorphous polymers by mechanical spectroscopy, and reveal the cooperative nature of the sub-Rouse modes.
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Reddick, Christopher, Yueping Zheng, and Bruce Perlman. "Channel choice in China." Transforming Government: People, Process and Policy 14, no. 1 (March 19, 2020): 81–100. http://dx.doi.org/10.1108/tg-11-2019-0105.
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Purpose This paper aims to examine the influence of user characteristics on preference for government service delivery channels. Preferences are understood as citizen use of and satisfaction with digital and traditional government contact modalities. User characteristics are represented by three constructs encapsulating the key elements of citizen features and attitudes. Design/methodology/approach The constructs are tested on data from a survey of 30 cities in China, resulting in 3,000 respondents, which asked questions on respondents’ use of and satisfaction with traditional modes (hotlines and service center channels) and digital modes (e-government and m-government channels) as well as respondents’ sociodemographics, technological capacity and view of government. Findings The results showed two important findings. First, service channel use was related to the first and second constructs (sociodemographics and technological capacity). Second, service channel satisfaction showed strong evidence of relation to the third construct, view of government. Research limitations/implications The results of this study make an empirical contribution to understanding the features of citizens that influence channel choice for public service contacts. Originality/value This study contributes to the understanding of channel choice in three areas. First, it is an empirical study using survey data and so adds to a largely case-based and conceptual literature. Second, by looking at the impact of citizen attitudes about government and not just their sociodemographic features. Third, by examining channel choice in the context of a fast-developing country like China.
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Myriokefalitakis, Stelios, Elisa Bergas-Massó, María Gonçalves-Ageitos, Carlos Pérez García-Pando, Twan van Noije, Philippe Le Sager, Akinori Ito, et al. "Multiphase processes in the EC-Earth model and their relevance to the atmospheric oxalate, sulfate, and iron cycles." Geoscientific Model Development 15, no. 7 (April 8, 2022): 3079–120. http://dx.doi.org/10.5194/gmd-15-3079-2022.
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Abstract. Understanding how multiphase processes affect the iron-containing aerosol cycle is key to predicting ocean biogeochemistry changes and hence the feedback effects on climate. For this work, the EC-Earth Earth system model in its climate–chemistry configuration is used to simulate the global atmospheric oxalate (OXL), sulfate (SO42-), and iron (Fe) cycles after incorporating a comprehensive representation of the multiphase chemistry in cloud droplets and aerosol water. The model considers a detailed gas-phase chemistry scheme, all major aerosol components, and the partitioning of gases in aerosol and atmospheric water phases. The dissolution of Fe-containing aerosols accounts kinetically for the solution's acidity, oxalic acid, and irradiation. Aerosol acidity is explicitly calculated in the model, both for accumulation and coarse modes, accounting for thermodynamic processes involving inorganic and crustal species from sea salt and dust. Simulations for present-day conditions (2000–2014) have been carried out with both EC-Earth and the atmospheric composition component of the model in standalone mode driven by meteorological fields from ECMWF's ERA-Interim reanalysis. The calculated global budgets are presented and the links between the (1) aqueous-phase processes, (2) aerosol dissolution, and (3) atmospheric composition are demonstrated and quantified. The model results are supported by comparison to available observations. We obtain an average global OXL net chemical production of 12.615 ± 0.064 Tg yr−1 in EC-Earth, with glyoxal being by far the most important precursor of oxalic acid. In comparison to the ERA-Interim simulation, differences in atmospheric dynamics and the simulated weaker oxidizing capacity in EC-Earth overall result in a ∼ 30 % lower OXL source. On the other hand, the more explicit representation of the aqueous-phase chemistry in EC-Earth compared to the previous versions of the model leads to an overall ∼ 20 % higher sulfate production, but this is still well correlated with atmospheric observations. The total Fe dissolution rate in EC-Earth is calculated at 0.806 ± 0.014 Tg yr−1 and is added to the primary dissolved Fe (DFe) sources from dust and combustion aerosols in the model (0.072 ± 0.001 Tg yr−1). The simulated DFe concentrations show a satisfactory comparison with available observations, indicating an atmospheric burden of ∼0.007 Tg, resulting in an overall atmospheric deposition flux into the global ocean of 0.376 ± 0.005 Tg yr−1, which is well within the range reported in the literature. All in all, this work is a first step towards the development of EC-Earth into an Earth system model with fully interactive bioavailable atmospheric Fe inputs to the marine biogeochemistry component of the model.
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Bencivenga, F., A. Calvi, F. Capotondi, R. Cucini, R. Mincigrucci, A. Simoncig, M. Manfredda, et al. "Four-wave-mixing experiments with seeded free electron lasers." Faraday Discussions 194 (2016): 283–303. http://dx.doi.org/10.1039/c6fd00089d.
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The development of free electron laser (FEL) sources has provided an unprecedented bridge between the scientific communities working with ultrafast lasers and extreme ultraviolet (XUV) and X-ray radiation. Indeed, in recent years an increasing number of FEL-based applications have exploited methods and concepts typical of advanced optical approaches. In this context, we recently used a seeded FEL to demonstrate a four-wave-mixing (FWM) process stimulated by coherent XUV radiation, namely the XUV transient grating (X-TG). We hereby report on X-TG measurements carried out on a sample of silicon nitride (Si3N4). The recorded data bears evidence for two distinct signal decay mechanisms: one occurring on a sub-ps timescale and one following slower dynamics extending throughout and beyond the probed timescale range (100 ps). The latter is compatible with a slower relaxation (time decay > ns), that may be interpreted as the signature of thermal diffusion modes. From the peak intensity of the X-TG signal we could estimate a value of the effective third-order susceptibility which is substantially larger than that found in SiO2, so far the only sample with available X-TG data. Furthermore, the intensity of the time-coincidence peak shows a linear dependence on the intensity of the three input beams, indicating that the measurements were performed in the weak field regime. However, the timescale of the ultrafast relaxation exhibits a dependence on the intensity of the XUV radiation. We interpreted the observed behaviour as the generation of a population grating of free-electrons and holes that, on the sub-ps timescale, relaxes to generate lattice excitations. The background free detection inherent to the X-TG approach allowed the determination of FEL-induced electron dynamics with a sensitivity largely exceeding that of transient reflectivity and transmissivity measurements, usually employed for this purpose.
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Faught, J. Tonigan, P. Balter, J. Johnson, S. Kry, L. Court, F. Stingo, and D. Followill. "SU-E-T-179: Clinical Impact of IMRT Failure Modes at Or Near TG-142 Tolerance Criteria Levels." Medical Physics 42, no. 6Part14 (June 2015): 3372–73. http://dx.doi.org/10.1118/1.4924540.
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Schmaltz, Brian, Yukinari Abe, and Kazuyuki Kohara. "Underfill Design for Low-k Dielectrics and Lead Free Applications." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2010, DPC (January 1, 2010): 001465–85. http://dx.doi.org/10.4071/2010dpc-wa34.
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As technology nodes progress to 32/28nm and beyond underfill materials are presented with the significantly challenging task of maintaining bump protection while ensuring ultra low-K dielectric (ULK/ELK) integrity. This challenge is further complicated by the trend toward RoHS compliancy(lead-free) and a ever increasing die size. Through extensive research and testing, several specifically formulated underfill materials were determined acceptable solutions for these complex issues. As technology nodes progress to smaller process generations a high stress concentration is seen at the dielectric layer during thermal cycling. This stress is a typical result of a high glass transition temperature (Tg) / high strength material that often leads to a cracking failure mode of the thin dielectric layer. Too low of a Tg presents a high stress concentration on the bumps which once again constitutes failure, this time however the crack is typically seen at the bump location. This high stress concentration seen at the bumps is more significant when lead free bumps are considered due to their inherent fragile nature. Underfill materials must now be specifically formulated and optimized to solve these failure modes for a large variable of package types. This paper will discuss solutions to typical failure modes currently seen with reliability testing of present and future technologies.
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Fisher, Robert J., Alan Rein, Matthew Fivash, Maria A. Urbaneja, José R. Casas-Finet, Maxine Medaglia, and Louis E. Henderson. "Sequence-Specific Binding of Human Immunodeficiency Virus Type 1 Nucleocapsid Protein to Short Oligonucleotides." Journal of Virology 72, no. 3 (March 1, 1998): 1902–9. http://dx.doi.org/10.1128/jvi.72.3.1902-1909.1998.
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ABSTRACT We have analyzed the binding of recombinant human immunodeficiency virus type 1 nucleocapsid protein (NC) to very short oligonucleotides by using surface plasmon resonance (SPR) technology. Our experiments, which were conducted at a moderate salt concentration (0.15 M NaCl), showed that NC binds more stably to runs of d(G) than to other DNA homopolymers. However, it exhibits far more stable binding with the alternating base sequence d(TG)n than with any homopolymeric oligodeoxyribonucleotide; thus, it shows a strong sequence preference under our experimental conditions. We found that the minimum length of an alternating d(TG) sequence required for stable binding was five nucleotides. Stable binding to the tetranucleotide d(TG)2 was observed only under conditions where two tetranucleotide molecules were held in close spatial proximity. The stable, sequence-specific binding to d(TG)n required that both zinc fingers be present, each in its proper position in the NC protein, and was quite salt resistant, indicating a large hydrophobic contribution to the binding. Limited tests with RNA oligonucleotides indicated that the preferential sequence-specific binding observed with DNA also occurs with RNA. Evidence was also obtained that NC can bind to nucleic acid molecules in at least two distinct modes. The biological significance of the specific binding we have detected is not known; it may reflect the specificity with which the parent Gag polyprotein packages genomic RNA or may relate to the functions of NC after cleavage of the polyprotein, including its role as a nucleic acid chaperone.
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Shi, La, Xiaolong Fu, Yang Li, Shuxin Wu, Saiqin Meng, and Jiangning Wang. "Molecular Dynamic Simulations and Experiments Study on the Mechanical Properties of HTPE Binders." Polymers 14, no. 24 (December 15, 2022): 5491. http://dx.doi.org/10.3390/polym14245491.
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The mechanical properties of HTPE binders have been systemically studied through combining the microstructure molecular simulations with macroscopic experiments. In this study, the crosslinking structures of HTPE binders were established by a computational procedure. Based on the optimized crosslinking models, the mechanical properties and the glass transition temperatures (Tg) of HTPE/N-100, HTPE/HDI, HTPE/TDI, and HTPE/IPDI binder systems were simulated; specifically, the Tg were 245.758 K, 244.573 K, 254.877 K, and 240.588 K, respectively. Then the bond-length distributions, conformation properties, cohesive energy densities, and fraction free volume were investigated to analyze how the microstructures of the crosslinking models influenced the mechanical properties of HTPE binders. Simultaneously, FTIR-ATR spectra analysis of HTPE binders proved that the special peaks, such as -NH and -NCO, could be seen in the crosslinking polyurethane structures synthesized between prepolymers and curing agents. The dynamic mechanical analysis was carried out, and it found that the Tg of HTPE/N-100, HTPE/HDI, HTPE/TDI, and HTPE/IPDI binder systems were −68.18 °C, −68.63 °C, −65.67 °C, and −68.66 °C, respectively. In addition, the uniaxial tension verified that both the ultimate stress and Young’s modulus of HTPE binder systems declined with the rising temperatures, while the strains at break presented a fluctuant variation. When it was closer to glass temperatures, especially −40 °C, the mechanical properties of HTPE binders were more prominent. The morphology of the fractured surface revealed that the failure modes of HTPE binders were mainly intermolecular slipping and molecular chain breakage. In a word, the experimental results were prospectively satisfied using the simulations, which confirmed the accuracy of the crosslinking models between prepolymers and curing agents. This study could provide a scientific option for the HTPE binder systems and guide the design of polyurethanes for composite solid propellant applications.
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Głuchowska, Halina, Renata Łyszczek, Liliana Mazur, and Alexander M. Kirillov. "Structural and Thermal Investigations of Co(II) and Ni(II) Coordination Polymers Based on biphenyl-4,4′-dioxydiacetate Linker." Materials 14, no. 13 (June 25, 2021): 3545. http://dx.doi.org/10.3390/ma14133545.
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Two coordination polymers, [Co(µ4-L)(H2O)2]n (1) and [Ni(µ-L)(H2O)4]n (2), were solvothermally assembled from the corresponding metal(II) chlorides and biphenyl-4,4-dioxydiacetic acid (H2L) as a flexible dicarboxylate linker. The cobalt(II) compound 1 featured a layer-pillared 3D metal-organic network with a cds topology, while the nickel(II) derivative 2 represented a linear chain 1D coordination polymer with a 2C1 topology. The µ4− and µ-L2− linkers exhibited different denticity and coordination modes in the synthesized compounds, thus contributing to their structural diversity. The dimensionality of 1 and 2 had an influence on their thermal stability and decomposition processes, which were investigated in detail by TG-DSC and TG-FTIR methods. Thermal decomposition products of coordination polymers were also analyzed by PXRD, confirming the formation of Co3O4/CoO and NiO as final materials. The obtained compounds broaden a family of coordination polymers assembled from flexible dicarboxylate linkers.
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Schmaltz, Brian, Yukinari Abe, and Kazuyuki Kohara. "Packaging Materials for Flip Chip and WLP: Underfill Design Using FEM for FC-BGA, FC-CSP, and Moving Towards 2.5/3D." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2014, DPC (January 1, 2014): 001295–327. http://dx.doi.org/10.4071/2014dpc-wa22.
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As technology nodes progress to 16/14nm and beyond underfill materials are presented with the significantly challenging task of maintaining bump protection while ensuring low warpage for ultra low-K dielectric (ULK/ELK) integrity. This challenge is further complicated by the trend toward RoHS compliancy (lead-free) and an ever increasing die size (beyond 25x25mm). Through extensive research and testing, several specifically formulated underfill materials were determined acceptable solutions for these complex issues. As technology nodes progress to smaller processes high stress concentrations are seen at the dielectric layer during thermal cycling. This stress is a typical result of a high glass transition temperature (Tg) / high strength material that often leads delamination or a cracking failure mode of the thin dielectric layer. Too low of a Tg presents a high stress concentration on the bumps which once again constitutes failure, this time, however, the crack is typically seen at the bump location. This high stress concentration seen at the bumps is more significant when lead free bumps are considered due to their inherent fragile nature. Underfill materials must now be specifically optimized for variable package conditions to solve these failure modes for a large variation of package designs. Desired material properties must be quickly calculated using finite element methods. This paper will discuss solutions to typical failure modes currently seen in reliability testing of present and future technologies.
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von Hellfeld, Rebecca, Pauline Pannetier, and Thomas Braunbeck. "Specificity of time- and dose-dependent morphological endpoints in the fish embryo acute toxicity (FET) test for substances with diverse modes of action: the search for a “fingerprint”." Environmental Science and Pollution Research 29, no. 11 (October 13, 2021): 16176–92. http://dx.doi.org/10.1007/s11356-021-16354-4.
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AbstractThe fish embryo acute toxicity (FET) test with the zebrafish (Danio rerio) embryo according to OECD TG 236 was originally developed as an alternative test method for acute fish toxicity testing according to, e.g., OECD TG 203. Given the versatility of the protocol, however, the FET test has found application beyond acute toxicity testing as a common tool in environmental hazard and risk assessment. Whereas the standard OECD guideline is restricted to four core endpoints (coagulation as well as lack of somite formation, heartbeat, and tail detachment) for simple, rapid assessment of acute toxicity, further endpoints can easily be integrated into the FET test protocol. This has led to the hypothesis that an extended FET test might allow for the identification of different classes of toxicants via a “fingerprint” of morphological observations. To test this hypothesis, the present study investigated a set of 18 compounds with highly diverse modes of action with respect to acute and sublethal endpoints. Especially at higher concentrations, most observations proved toxicant-unspecific. With decreasing concentrations, however, observations declined in number, but gained in specificity. Specific observations may at best be made at test concentrations ≤ EC10. The existence of a “fingerprint” based on morphological observations in the FET is, therefore, highly unlikely in the range of acute toxicity, but cannot be excluded for experiments at sublethal concentrations.
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Colmenero, J. "Universal Trend of the Non-Exponential Rouse Mode Relaxation in Glass-Forming Polymers Systems: Experimental Facts, MD-Simulation Results and a Theoretical Approach Based on a Generalized Langevin Equation." MRS Advances 1, no. 26 (2016): 1903–13. http://dx.doi.org/10.1557/adv.2016.54.
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ABSTRACTNowadays there are clear evidences from both experiments and MD-simulations proving that the chain Rouse modes correlation functions are non-exponential in unentangled polymer blends and also in pure polymers at low temperature (with respect to that of the glass transition Tg) even for the long wavelengths modes where local potentials and chain stiffness should not play any role. In a recent paper [S. Arrese-Igor et al, Phys. Rev. Lett.113, 078302 (2014)] it has been proposed that this non-exponential behavior depends on the ratio between the so-called Rouse time - i.e., the characteristic time of the slowest chain mode relaxation - and the time scale of the α-relaxation. This parameter is in some way ‘universal’ in the meaning that it can encode many different experimental situations. In this paper, we show that this behavior can be quantitatively explained in the framework of a theoretical approach based on: (i) a generalized Langevin equation (GLE) formalism and (ii) a memory function which takes into account the effect of collective dynamics on the chain dynamics of a tagged chain and which was constructed taking inspirations from the original ideas of the reptation model proposed by de Gennes.
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Shi, Ji Yan, Li Ren Fan, Ji Qing Song, and Wen Bo Bai. "Swelling Properties and Kinetics of Starch-g-Poly(acrylic acid) Hydrogels." Advanced Materials Research 550-553 (July 2012): 1316–20. http://dx.doi.org/10.4028/www.scientific.net/amr.550-553.1316.
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Starch-g-poly(acrylic acid) (CSt-g-PAA) hydrogels were prepared from cassava starch and acrylic acid by graft polymerization. The hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric-differential scanning calorimetry (TG-DSC). Additionally, the water absorbency and hygroscopic swelling properties of the hydrogels were investigated respectively. The two processes were simulated using mathematical modes. The results revealed that the crystal structure of starch was destroyed. At 40°C and relative humidity 90% (90% RH), the samples (starch mass15%, 50%) have a better performance of the moisture absorption. Hygroscopic rate declined with the increase of relative humidity.
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Duan, Hong-Guang, Ajay Jha, Xin Li, Vandana Tiwari, Hanyang Ye, Pabitra K. Nayak, Xiao-Lei Zhu, et al. "Intermolecular vibrations mediate ultrafast singlet fission." Science Advances 6, no. 38 (September 2020): eabb0052. http://dx.doi.org/10.1126/sciadv.abb0052.
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Singlet fission is a spin-allowed exciton multiplication process in organic semiconductors that converts one spin-singlet exciton to two triplet excitons. It offers the potential to enhance solar energy conversion by circumventing the Shockley-Queisser limit on efficiency. We study the primary steps of singlet fission in a pentacene film by using a combination of TG and 2D electronic spectroscopy complemented by quantum chemical and nonadiabatic dynamics calculations. We show that the coherent vibrational dynamics induces the ultrafast transition from the singlet excited electronic state to the triplet-pair state via a degeneracy of potential energy surfaces, i.e., a multidimensional conical intersection. Significant vibronic coupling of the electronic wave packet to a few key intermolecular rocking modes in the low-frequency region connect the excited singlet and triplet-pair states. Along with high-frequency local vibrations acting as tuning modes, they open a new channel for the ultrafast exciton transfer through the resulting conical intersection.
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Heusinkveld, Harm J., Paul F. K. Wackers, Willem G. Schoonen, Leo van der Ven, Jeroen L. A. Pennings, and Mirjam Luijten. "Application of the comparison approach to open TG-GATEs: A useful toxicogenomics tool for detecting modes of action in chemical risk assessment." Food and Chemical Toxicology 121 (November 2018): 115–23. http://dx.doi.org/10.1016/j.fct.2018.08.007.
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Liégeois, Vincent, Christoph R. Jacob, Benoît Champagne, and Markus Reiher. "Analysis of Vibrational Raman Optical Activity Signatures of the (TG)Nand (GG)NConformations of Isotactic Polypropylene Chains in Terms of Localized Modes." Journal of Physical Chemistry A 114, no. 26 (July 8, 2010): 7198–212. http://dx.doi.org/10.1021/jp102739g.
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Jaishree, D., G. Kanchana, and R. Kesavasamy. "Investigations on Growth, Optical and Thermal Properties of Sulphamic Acid Single Crystals." Advances in Condensed Matter Physics 2014 (2014): 1–5. http://dx.doi.org/10.1155/2014/950467.
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Single crystals of sulphamic acid of 11 × 7 × 3 mm3dimension were successfully grown by slow evaporation technique. The crystal structure of grown crystals was confirmed by single crystal X-ray diffraction analysis. The presence of functional groups in the crystal lattice has been qualitatively determined by FT-IR and FT-Raman analyses. Theoretical group factor analysis predicts the possible modes of vibrations. The optical transmission spectroscopy (UV-Vis) clearly evidences the suitability of this material for optical application. The thermal behaviour of the crystal was studied by thermogravimetric (TG) and differential scanning calorimetric (DSC) studies. The nonlinear optical (NLO) characteristic of this material was explored by the second harmonic generation (SHG) conversion efficiency.
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Brockner, Wolfgang, Robert Branscheid, Mimoza Gjikaj, and Arnold Adam. "Synthesis, Crystal Structure and Vibrational Spectrum of Cobalt(II)orotate Trihydrate, [Co(C5N2O4H2) · 3 H2O." Zeitschrift für Naturforschung B 60, no. 2 (February 1, 2005): 175–79. http://dx.doi.org/10.1515/znb-2005-0208.
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Cobalt orotate trihydrate, [Co(C5N2O4H2)]·3H2O, has been synthesized and its crystal structure determined. The title compound crystallizes in the orthorhombic space group P212121 (no. 19) with a = 771.5(2), b = 788.9(7), c = 1470.4(2) pm, and Z = 4. Bridging orotate anions coordinate in a mono- and bidentate manner to the Co atom resulting in infinite chains of alternating Co(II) cations and orotate (OrH2−) anions parallel to the c axis. The distorted octahedral Co coordination geometry is completed by three H2 molecules. The FT-Raman and FT-IR spectra of the crystalline compound have been recorded and an assignment of the vibrational modes is proposed. The thermal behavior (TG) was investigated.
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Jahani, Younes, Marta Baena, Javier Gómez, Cristina Barris, and Lluís Torres. "Experimental Study of the Effect of High Service Temperature on the Flexural Performance of Near-Surface Mounted (NSM) Carbon Fiber-Reinforced Polymer (CFRP)-Strengthened Concrete Beams." Polymers 13, no. 6 (March 17, 2021): 920. http://dx.doi.org/10.3390/polym13060920.
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This paper presents a study of the effect of high service temperature (near or beyond glass transition temperature (Tg) of structural epoxy adhesive) on the behavior of near-surface mounted (NSM) carbon fiber-reinforced polymer (CFRP)-strengthened reinforced concrete (RC) beams. The study includes experimental work as well as analytical and numerical analysis. To this end, fourteen beams have been tested up to failure in two different series. In series 1, specimens with three different CFRP areas have been tested at two different temperatures (i.e., 20 and 40 °C). In series 2, and with the aim of evaluating the effect of higher temperatures, only one CFRP area was tested under four different temperatures (i.e., 20, 60, 70, and 85 °C). Experimental results are evaluated in terms of load–deflections, failure modes, and bond performance. Furthermore, the experimental load–deflection curves are satisfactorily compared to both analytical predictions and finite element (FE) numerical simulations. In both cases, shrinkage and temperature effects on the short-term response of flexural elements have been accounted for. No significant reduction in stiffness and ultimate load was observed for specimens being tested up to 60 °C (in the range of epoxy Tg), showing FRP rupture failure in all of them. For specimens under 70 and 85 °C, the failure mode changed from FRP rupture to FRP end debonding and concrete crushing, respectively.
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Chonnaparamutt, Winai, and Witsarut Supsi. "SEFRE: Semiexoskeleton Rehabilitation System." Applied Bionics and Biomechanics 2016 (2016): 1–12. http://dx.doi.org/10.1155/2016/8306765.
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SEFRE (Shoulder-Elbow-Forearm Robotics Economic) rehabilitation system is presented in this paper. SEFRE Rehab System is composed of a robotic manipulator and an exoskeleton, so-called Forearm Supportive Mechanism (FSM). The controller of the system is developed as the Master PC consisting of five modules, that is, Intelligent Control (IC), Patient Communication (PC), Training with Game (TG), Progress Monitoring (PM), and Patient Supervision (PS). These modules support a patient to exercise with SEFRE in six modes, that is, Passive, Passive Stretching, Passive Guiding, Initiating Active, Active Assisted, and Active Resisted. To validate the advantages of the system, the preclinical trial was carried out at a national rehabilitation center. Here, the implement of the system and the preclinical results are presented as the verifications of SEFRE.
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Ngai, K. L., and D. J. Plazek. "Identification of Different Modes of Molecular Motion in Polymers That Cause Thermorheological Complexity." Rubber Chemistry and Technology 68, no. 3 (July 1, 1995): 376–434. http://dx.doi.org/10.5254/1.3538749.
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Abstract The viscoelastic properties of amorphous polymers are reviewed with emphasis on the glass to rubber dispersion (often referred to as the transition zone). Deviations from thermorheologieal simplicity (where molecular retardation and relaxation mechanisms have the same temperature dependence) are identified. Most theories and models of polymer chain dynamics do not address or acknowledge thermorheological complexities and correlations, such as that between the temperature dependence and the breadth of viscoelastic and dielectric dispersions of the local segmental motion. Without successful theories of these phenomena the understanding of polymer chain dynamics must be considered incomplete. In this review, old and new experimental data are used to identify the different modes of molecular motions and the domains of their contributions to the time and frequency dependence of the mechanical response of amorphous polymers. The different modes are then shown generally to have their own dependence on temperature. Thus the viscoelastic spectrum, including local segmental motions which dominate the onset of glassy behavior and largely determine the glass temperature, Tg, the glass to rubber softening dispersion, the rubbery plateau and the terminal zone, is thermorheologically complex. A coupling theory, with the physics of intermolecular interactions and cooperativity built into it, describes well the many-body dynamics of densely packed molecular systems such as polymers. The many predictions of the coupling theory are applied to the different viscoeleatic modes to explain the observed anomalous experimental facts and established correlations. The theoretical understanding has been improved to the extent that now a connection can be made between the chemical structure of the monomer and the viscoelastic properties of the polymer.
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Reckeweg, Olaf, Robert E. Dinnebier, Armin Schulz, Björn Blaschkowski, Christof Schneck, and Thomas Schleid. "About the air- and water-stable copper(I) dicyanamide: synthesis, crystal structure, vibrational spectra and DSC/TG analysis of Cu[N(CN)2]." Zeitschrift für Naturforschung B 72, no. 2 (February 1, 2017): 159–65. http://dx.doi.org/10.1515/znb-2016-0228.
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AbstractLight-yellow microcrystalline samples of Cu[dca] ([dca]−≡[N(CN)2]−≡dicyanamide anion) were obtained by blending an in-situ generated aqueous Cu+ brine with stoichiometric amounts of Na[dca] dissolved in water. The crystal structure of Cu[dca] was solved and refined from powder X-ray diffraction (PXRD) data. Cu[dca] crystallizes in the orthorhombic space group Cmcm (no. 63) with the lattice parameters of a=356.28(3), b=611.10(9) and c=1525.87(10) pm. The crystal structure contains undulated chains of alternating Cu+ and boomerang-shaped [N≡C–N–C≡N]− ions with C2v symmetry running along [100]. It is closely related to that of Ag[dca] crystallizing in space group Pnma (no. 62). The vibrational spectra for Cu[dca] and Cu[dca]2 were recorded exhibiting modes typical for the dicyanamide anion. Comparative DSC/TG measurements were performed for both copper dicyanamides and the cyanide Cu[CN].
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D’amore, Alberto, and Luigi Grassia. "The Anomalies of Polymers at Nanoscale as a Tool to Enhance the Fatigue Life of Structural Composites." Materials Science Forum 957 (June 2019): 259–66. http://dx.doi.org/10.4028/www.scientific.net/msf.957.259.
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The “in service “properties' of high performance composites degrade due to the development of different damage modes occurring hierarchically at different length and time (cycles) scales, from diffuse crackand crazing within the polymer matrix, to fiber-matrix interface failure, to ply rupture and delamination where catastrophic failure occurs. The density of cracks within the matrix saturates at very early stage of the service life of the composite component and this “Critical Damage State” (CDS) triggers the other damage modes. Thus, shifting the CDS toward higher number of cycles allows enhancing the overall fatigue performances of composites, that is the main objective of our proposal. The matrix weakness is due to the residual stresses (of order of magnitude of the matrix strength) that accumulate as consequence of the manufacturing process. In order to relax the residual stresses we propose to take advantage of the anomalies of nanoconfined thermoplastic polymers that show a negative coefficient ofthermal expansion at temperatures below Tg. Silica microspheres can be covered by polymer shells of 10-40 nanometers and added to the reactive resin in order to counter balance the resin contraction through the expansion of the nanoconfined polymer, during cooling.
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Boukhelf, Fouad, Daniel Lira Lopes Targino, Mohammed Hichem Benzaama, Lucas Feitosa de Albuquerque Lima Babadopulos, and Yassine El Mendili. "Insight into the Behavior of Mortars Containing Glass Powder: An Artificial Neural Network Analysis Approach to Classify the Hydration Modes." Materials 16, no. 3 (January 19, 2023): 943. http://dx.doi.org/10.3390/ma16030943.
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In this paper, an artificial neural network (ANN) model is proposed to predict the hydration process of a new alternative binder. This model overcomes the lack of input parameters of physical models, providing a realistic explanation with few inputs and fast calculations. Indeed, four mortars are studied based on ordinary Portland cement (CEM I), cement with limited environmental impact (CEM III), and glass powder (GP) as the cement substitution. These mortars are named CEM I + GP and CEM III + GP. The properties of the mortars are characterized, and their life cycle assessment (LCA) is established. Indeed, a decrease in porosity is observed at 90 days by 4.6%, 2.5%, 12.4%, and 7.9% compared to those of 3 days for CEMI, CEMIII, CEMI + GP, and CEMIII + GP, respectively. In addition, the use of GP allows for reducing the mechanical strength in the short term. At 90 days, CEMI + GP and CEMIII + GP present a decrease of about 28% and 57% in compressive strength compared to CEMI and CEMIII, respectively. Nevertheless, strength does not cease increasing with the curing time, due to the continuous pozzolanic reactions between Ca(OH)2 and silica contained in GP and slag present in CEMIII as demonstrated by the thermo-gravimetrical (TG) analysis. To summarize, CEMIII mortar provides similar performance compared to mortar with CEMI + GP in the long term. This can later be used in the construction sector and particularly in prefabricated structural elements. Moreover, the ANN model used to predict the heat of hydration provides a similar result compared to the experiment, with a resulting R² of 0.997, 0.968, 0.968, and 0.921 for CEMI, CEMIII, CEMI + GP, and CEMIII + GP, respectively, and allows for identifying the different hydration modes of the investigated mortars. The proposed ANN model will allow cement manufacturers to quickly identify the different hydration modes of new binders by using only the heat of hydration test as an input parameter.
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Margaret, S. Mary, Albin John P. Paul Winston, S. Muthupandi, P. Shobha, and P. Sagayaraj. "A Comparative Study of Nanostructures of CuO/Cu2O Fabricated via Potentiostatic and Galvanostatic Anodization." Journal of Nanomaterials 2021 (August 14, 2021): 1–8. http://dx.doi.org/10.1155/2021/5533845.
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A detailed comparative study on the synthesis process of coral-like CuO/Cu2O nanorods (NRs) and nanopolycrystals (NPCs) fabricated on Cu foil employing aqueous electrolyte via potentiostatic (POT) and galvanostatic (GAL) modes is discussed. The structural, morphological, thermal, compositional, and molecular vibration of the prepared CuO/Cu2O nanostructures was characterized by XRD, HRSEM, TG/DTA, FTIR, and EDX techniques. XRD analysis confirmed the crystalline phase of the formation of monoclinic CuO and cubic Cu2O nanostructures with well-defined morphology. The average particle size was found to be 21.52 nm and 26.59 nm for NRs (POT) and NPCs (GAL), respectively, and this result is corroborated from the HRSEM analysis. POT synthesized nanoparticle depicted a higher thermal stability up to 600°C implying that the potentiostatically grown coral-like NRs exhibit a good crystallinity and well-ordered morphology.
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Roelofs, G. J. "A GCM study of organic matter in marine aerosol and its potential contribution to cloud drop activation." Atmospheric Chemistry and Physics Discussions 7, no. 2 (April 27, 2007): 5675–700. http://dx.doi.org/10.5194/acpd-7-5675-2007.
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Abstract. With the global aerosol-climate model ECHAM5-HAM we investigate the potential influence of organic aerosol originating from the ocean on aerosol mass and chemical composition and the droplet concentration and size of marine clouds. We present sensitivity simulations in which the uptake of organic matter in the marine aerosol is prescribed for each aerosol mode with varying organic mass and mixing state, and with a geographical distribution and seasonality similar to the oceanic emission of dimethyl sulfide. Measurements of aerosol mass and chemical composition serve to evaluate the representativity of the model initializations. Good agreement with the measurements is obtained when organic matter is added to the Aitken, accumulation and coarse modes simultaneously. Representing marine organics in the model leads to higher cloud drop number concentrations, smaller cloud drop effective radii, and a better agreement with remote sensing measurements. The mixing state of the organics and the other aerosol matter, i.e., internal or external depending on the formation process of aerosol organics, is an important factor for this. We estimate that globally about 75 Tg C yr−1 of organic matter from marine origin enters the aerosol phase. An approximate 35% of this occurs through formation of secondary organic aerosol and 65% through emission of primary particles.
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Roelofs, G. J. "A GCM study of organic matter in marine aerosol and its potential contribution to cloud drop activation." Atmospheric Chemistry and Physics 8, no. 3 (February 13, 2008): 709–19. http://dx.doi.org/10.5194/acp-8-709-2008.
Full textAbstract:
Abstract. With the global aerosol-climate model ECHAM5-HAM we investigate the potential influence of organic aerosol originating from the ocean on aerosol mass and chemical composition and the droplet concentration and size of marine clouds. We present sensitivity simulations in which the uptake of organic matter in the marine aerosol is prescribed for each aerosol mode with varying organic mass and mixing state, and with a geographical distribution and seasonality similar to the oceanic emission of dimethyl sulfide. Measurements of aerosol mass, aerosol chemical composition and cloud drop effective radius are used to assess the representativity of the model initializations. Good agreement with the measurements is obtained when organic matter is added to the Aitken, accumulation and coarse modes simultaneously. Representing marine organics in the model leads to higher cloud drop number concentrations and thus smaller cloud drop effective radii, and this improves the agreement with measurements. The mixing state of the organics and the other aerosol matter, i.e. internal or external depending on the formation process of aerosol organics, is an important factor for this. We estimate that globally about 75 Tg C yr−1 of organic matter from marine origin enters the aerosol phase, with comparable contributions from primary emissions and secondary organic aerosol formation.
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Jiao, Ti Feng, Jian Liu, Li Hua Gao, Jing Xin Zhou, and Yuan Yuan Xing. "Research on Some Aromatic Schiff Base Compounds and Metal Complexes with Different Substituted Groups." Key Engineering Materials 474-476 (April 2011): 1523–28. http://dx.doi.org/10.4028/www.scientific.net/kem.474-476.1523.
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Two aromatic Schiff base derivatives and the corresponding metal complexes with different substituted groups were synthesized and characterized by many methods. The products were characterized by UV-Vis spectra, FT-IR spectra and thermal analysis, while the thermal stability was measured by TG-DTA instrument. FT-IR analysis indicated that the nitrogen atom in imino group and oxygen atom in phenolic hydroxyl group participated in coordinating with transition metal ion in different bridged mode. UV spectra also verified that different coordination modes can be performed between metal ions and ligands. In addition, the thermal stability of metal complexes had been obviously superior to that of the ligands. All results give a useful clue to obtain Schiff base derivatives with versatile property by regulating intramolecular substituted group and species of metal ion. The present results have showed potential application in fields of functional material and catalyst.