scholarly journals The Nano-Confinement Effect on the SCO Behavior of [Fe(NH2trz)3](NO3)2 1D Chains in MCM-41

Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 639
Author(s):  
Tian Zhao ◽  
Hexin Zhu ◽  
Ming Dong
Keyword(s):  
Magnetic Measurement ◽  
Spin Transition ◽  
Magnetic Data ◽  
Transition Curve ◽  
Polymeric Chain ◽  
Infrared Spectrometry ◽  
Confinement Pressure ◽  
Significant Difference ◽  
Temperature Variable ◽  
Mcm 41

A polymeric chain spin-crossover (SCO) compound [Fe(NH2trz)3](NO3)2 was embedded in the pores of mesoporous silica MCM-41, which yielded an M@S composite. The obtained material was characterized by infrared spectrometry, powder X-ray diffractometry, gas sorption studies, electron microscopy, and atomic absorption. The temperature-induced SCO behavior of the composite was monitored by temperature-variable magnetic measurement. The results indicate that the spin transition curve of the composite was evidently shifted to a higher temperature in comparison to bulk [Fe(NH2trz)3](NO3)2. The shift in the transition temperature for M@S [versus bulk [Fe(NH2trz)3](NO3)2] amounted to Tc↑ = 362 K [347 K] and Tc↓ = 327 K [314 K] (magnetic data). The significant difference in the SCO behavior of [Fe(NH2trz)3](NO3)2 when embedded in the MCM-41 matrix may be attributed to the strengthened cooperativity of compound S and the nano-confinement pressure of SiO2 walls.

scholarly journals Water effect on the spin-transition behavior of Fe(ii) 1,2,4-triazole 1D chains embedded in pores of MCM-41

2015 ◽  
Vol 3 (30) ◽  
pp. 7802-7812 ◽  
Author(s):  
Tian Zhao ◽  
Laure Cuignet ◽  
Marinela Maria Dîrtu ◽  
Mariusz Wolff ◽  
Vojislav Spasojevic ◽  
...  
Keyword(s):  
Matrix Effect ◽  
Spin Transition ◽  
Water Effect ◽  
Transition Behavior ◽  
Confinement Pressure ◽  
1D Chains ◽  
Mcm 41

Water is crucial in exerting a confinement pressure or matrix effect on the spin transition of the SCO material in MCM-41.

scholarly journals Fractographic Analysis Of Selected Boron Steels Subjected To Impact Testing

2015 ◽  
Vol 60 (3) ◽  
pp. 2373-2378 ◽  
Author(s):  
W. Dudziński ◽  
Ł. Konat ◽  
B. Białobrzeska
Keyword(s):  
Transition Temperature ◽  
Impact Testing ◽  
Transition Curve ◽  
Brittle Transition ◽  
Significant Difference ◽  
Brittle Transition Temperature ◽  
Ductile To Brittle Transition ◽  
Character Of Fracture ◽  
The Impact ◽  
Boron Steels

Abstract In this paper dynamic properties of low-alloy boron steels – Hardox 500, B27 and HTK 900H in delivered state (after hardening and tempering) are considered. Charpy V-notch (CVN) test results in connection with fractography in the ductile-to-brittle transition temperature region were analyzed. Obtained from CVN test the impact transition curve, not always predicts properly a behavior of materials in conditions of dynamic loading. So an analyze of character of fracture helps to evaluate the real behavior of materials. Tested samples were cut out longitudinally in relation to cold work direction. The results of CVN test for selected steels, in temperatures: −40°C, −20°C, 0°C and +20°C are presented. Regarding ductile-to-brittle transition temperature, there is a significant difference taking into account values of Charpy V energy absorbed and a character of fracture.

Deep-tow 3C magnetic measurement: Solutions for calibration and interpretation

Geophysics ◽  
2013 ◽  
Vol 78 (3) ◽  
pp. J15-J23 ◽  
Author(s):  
Adrien Bronner ◽  
Marc Munschy ◽  
Daniel Sauter ◽  
Julie Carlut ◽  
Roger Searle ◽  
...  
Keyword(s):  
Magnetic Measurement ◽  
Magnetic Data ◽  
Linear Inversion ◽  
First Order ◽  
Anomalous Field ◽  
Magnetization Intensity ◽  
Calibration Experiment ◽  
New Type ◽  
Equivalent Layer ◽  
Three Components

Two main problems are encountered in deep-tow 3C magnetic surveys. The first problem is related to instrumental error due to the manufacturing of the sensor, its integration in the towed fish structure, and the magnetization of the vehicle carrying the magnetometer; the second is related to the variation in altitude of the instruments during the dive. We evaluated a new type of calibration approach for deep-tow fluxgate magnetometers. We found that the magnetometer can be calibrated with no recourse to the vehicle attitude (pitch, roll, and heading, as it is usually achieved) but only using the three components recorded by the magnetometer and an approximation of the scalar intensity of the earth’s magnetic field. This method, called scalar calibration, allowed us to eliminate the intrinsic instrumental errors as well as the magnetization effect of the tow vehicle. Thus, despite the low maneuverability of the towed fish during the calibration experiment, we discovered a significant improvement in obtaining accurate magnetic anomaly profiles. Because only the total field anomaly and not the magnetic vector is suitable for this method, we investigated the possibility of calculating the three components via an equivalent-source approach. Therefore, assuming a 2D topographic equivalent layer, we found a stable and a meaningful magnetization of the oceanic crust. We discovered that although magnetic data are acquired along uneven tracks, this model, based on a single linear inversion, is sufficient to provide a first-order depth and magnetization intensity of the crust and also to carry out upward continuation of the total anomalous field as well as its associated vector.

scholarly journals Mycoplasma agalactiae and the Mycoplasma mycoides cluster in goat herds in the states of Pernambuco and Paraíba, Brazil

2019 ◽  
Vol 40 (5Supl1) ◽  
pp. 2261
Author(s):  
Luciana Florêncio Vilaça Lopes ◽  
Elizabete Cristina da Silva ◽  
Anidene Christina Alves de Moraes ◽  
Elizabete Rodrigues da Silva ◽  
Kleber Régis Santoro ◽  
...  
Keyword(s):  
Goat Milk ◽  
Milk Composition ◽  
Infrared Spectrometry ◽  
Mean Values ◽  
Mycoplasma Agalactiae ◽  
Milk Samples ◽  
Significant Difference ◽  
Mycoplasma Mycoides ◽  
Etiological Agents ◽  
Species Specific

The objective of this study was to detect Mycoplasma agalactiae (Ma) and the Mycoplasma mycoides cluster (Mmcluster) in 373 goat milk samples of different breeds from herds located in Pernambuco and Paraíba states, as well as to evaluate somatic cell count (SCC) and milk composition from positive animals. For this, DNA extraction from milk samples was carried out, followed by generic and species-specific amplification by Polymerase Chain Reaction (PCR). Milk constituents were determined by medium infrared spectrometry and SCC by flow cytometry. Analyses of variance and tests of comparison of means verified the effects of positivity on the evaluated characteristics. The frequencies for Ma and Mmcluster were 43.21 and 5.70%, respectively. In all genetic groups, Ma was detected in all positive samples, whereas Mmcluster was only observed in samples from Moxotó, Parda Sertaneja, and that without a defined racial pattern. Statistical difference was observed (p < 0.05) between mean values of protein, casein and SCC in positive and negative Ma samples. In terms of Mmcluster there was only a statistically significant difference in the SCC parameter. The detection of Mycoplasma in samples of goat milk suggests an introduction of infected animals into the evaluated herds, as well as possible contact with the etiological agents at fairs and exhibitions.

Metal-Complexes of 1,10-Phenanthroline Derivatives. XV. Complexes of 2-(3,5-Dimethylpyrazol-1-yl)-1,10-phenanthroline

1988 ◽  
Vol 41 (6) ◽  
pp. 873 ◽  
Author(s):  
AS Abushamleh ◽  
HA Goodwin
Keyword(s):  
Magnetic Properties ◽  
Solid State ◽  
Spectral Data ◽  
High Spin ◽  
Nickel Complex ◽  
Spin Transition ◽  
Critical Value ◽  
Magnetic Data ◽  
Strong Temperature Dependence ◽  
Thermally Induced

Iron(II) and nickel(II) bis ( ligand ) complexes of 2-(3,5-dimethylpyrazol-1-yl)-1,10-phenanthroline (L) have been prepared. The field strength of L as determined from spectral data for the nickel complex is in the range encompassing the critical value at the singlet (1A1) ↔ quintet (5T2) crossover for iron(II). The magnetic properties of the iron(II) complex both in solution and in the solid state are anomalous, and indicative of the occurrence of a thermally induced spin transition. Mossbauer spectral data confirm this, and reveal separate contributions from the singlet and quintet species with a strong temperature-dependence of their relative intensities. Magnetic data for the complex in solution are consistent with a simple high spin ↔ low spin equilibrium, and lead to values of ΔH = 23�0.5 kJ mol-1 and ΔS = 66�5 J K-1 mol-1 for the low spin → high spin transformation.

scholarly journals UTILIZATION OF RICE HUSK AS RAW MATERIAL IN SYNTHESIS OF MESOPOROUS SILICATES MCM-41

2011 ◽  
Vol 11 (3) ◽  
pp. 279-284 ◽  
Author(s):  
Suyanta Suyanta ◽  
Agus Kuncaka
Keyword(s):  
Ftir Spectroscopy ◽  
Sodium Silicate ◽  
Rice Husk ◽  
Hydrothermal Process ◽  
X Ray Diffraction ◽  
Rice Husk Silica ◽  
X Ray ◽  
Silica Source ◽  
Significant Difference ◽  
Mcm 41

The research about synthesis and characterization of MCM-41 from rice husk has been done. Silica (SiO2) was extracted from rice husk by refluxing with 3M hydrochloric solution at 80 °C for 3 h. The acid-leached rice husk was filtered, washed, dried and calcined at 650 °C for 6 h lead the rough powder of rice husk silica with light brown in color. Characterization was carried out by X-ray diffraction (XRD) and FTIR spectroscopy method. Rice husk silica was dissolved into the sodium hydroxide solution leading to the solution of sodium silicate, and used as silica source for the synthesis of MCM-41. MCM-41 was synthesized by hydrothermal process to the mixture prepared from 29 g of distilled water, 8.67 g of cetyltrimethyl ammonium bromide (CTMAB), 9.31 g of sodium silicate solution, and amount mL of 1 M H2SO4. Hydrothermal process was carried out at 100 °C in a teflon-lined stainless steel autoclave heated in the oven for 36 h. The solid phase was filtered, then washed with deionised water, and dried in the oven at 100 °C for 2 h. The surfactant CTMAB was removed by calcination at 550 °C for 10 h with heating rate 2 °C/min. The as-synthesized and calcined crystals were characterized by using FTIR spectroscopy, X-ray diffraction and N2 physisorption methods. In order to investigate the effect of silica source, the same procedure was carried out by using pure sodium silicate as silica source. It was concluded that silica extracted from rice husk can be used as raw materials in the synthesis of MCM-41, there is no significant difference in crystallinity and pore properties when was compared to material produced from commercial sodium silicate.

scholarly journals Hysteretic Thermal Spin-Crossover and Symmetry Breaking in Heteroleptic Fe(II) Complexes Using Alkyl Chain Substituted 2,2’-Dipyridylamine Ligands

2019 ◽  
Author(s):  
Blaise Geoghegan ◽  
Wasinee Phonsri ◽  
Peter Horton ◽  
James Orton ◽  
Simon Coles ◽  
...  
Keyword(s):  
Phase Transition ◽  
Spin Crossover ◽  
Alkyl Chain ◽  
Thermal Hysteresis ◽  
Variable Temperature ◽  
Spin Transition ◽  
Magnetic Data ◽  
Monoclinic Space Group ◽  
Space Group ◽  
Bond Lengths

The alkyl chain carrying ligands N,N-di(pyridin-2-yl)butanamide (LC4) and N,N-di(pyridin-2-yl)decanamide (LC10) were combined with NCS- co-ligands to form the neutral heteroleptic Fe(II) complexes trans-[FeII(LC4)2(NCS)2] (1C4) and trans [FeII(LC10)2(NCS)2] (1C10). Variable temperature crystallographic studies revealed that 1C4 is in the orthorhombic space group Pna21 between 85-200 K whereas 1C10 is in the monoclinic space group P21/c between 85-105 K before undergoing a crystallographic phase transition to the triclinic space group P1􀴤 by 140 K. The average Fe-N bond lengths suggest that at 85 K 1C4 contains LS Fe(II) centres; However, the ca. 0.18 Å increase in the average Fe-N bond lengths between 85 and 120 K suggests a spin-transition occurs within this temperature interval and the HS state is predominant beyond this. 1C10 contains LS Fe(II) centres between 85 and 105 K. Upon warming from 105 to 140 K the average Fe-N bond lengths increase by ca. 0.19 Å, which suggests that a spin-transition to the HS accompanies the P21/c to P1􀴤 crystallographic phase transition. Solid-state magnetic susceptibility measurements showed that 1C4 undergoes semi-abrupt spin-crossover with T1/2 = 127.5 K and a thermal hysteresis of ca. 13 K whereas, 1C10 undergoes an abrupt spin-crossover with T1/2 = 119.0 K, and is also accompanied by thermal hysteresis of ca. 4 K. The crystallographic and magnetic data show that the length of the complex’s alkyl chain substituents can have a large impact on the structure of the crystal lattice as well as a subtle effect on the T1/2 value for thermal spin-crossover.

Photo-induced spin-transition: the role of the iron(II) environment distortion

2005 ◽  
Vol 61 (1) ◽  
pp. 25-28 ◽  
Author(s):  
Mathieu Marchivie ◽  
Philippe Guionneau ◽  
Jean-François Létard ◽  
Daniel Chasseau
Keyword(s):  
Spin Crossover ◽  
Strong Dependence ◽  
Spin Transition ◽  
Magnetic Behaviour ◽  
Magnetic Data ◽  
Structural Parameter ◽  
Structure Property ◽  
Wide Range ◽  
Shed Light

The [FeL n (NCS)2] iron(II) spin-crossover complexes cover a wide range of magnetic behaviour. Owing to the large number of known structural and magnetic data, this series is perfectly adapted to the investigation of the structure–magnetic properties relationship. In this paper we propose a new structural parameter, denoted Θ, which is used to correlate the features of the spin-crossover phenomena with the distortion of the iron environment. In particular, this parameter has shed light on the role of such distortion on the limiting temperature of photo-inscription, known as T(LIESST). A strong dependence of T(LIESST) on Θ is clearly demonstrated. The stronger the distortion the higher the T(LIESST) value. This structure–property dependence represents, for instance, a powerful tool to estimate the highest potential T(LIESST) value for a series of complexes. This limit in the [FeL n (NCS)2] series is estimated to be around 120 K, which probably prevents their use in any industrial application.

scholarly journals 2D Layer Arrangement of Solely [HS-HS] or [LS-LS] Molecules in the [HS-LS] State of a Dinuclear Fe(II) Spin Crossover Complex

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 448
Author(s):  
Fabian Fürmeyer ◽  
Luca M. Carrella ◽  
Eva Rentschler
Keyword(s):  
Crystal Structure ◽  
Spin Crossover ◽  
Crystal Packing ◽  
Spin Transition ◽  
High Spin State ◽  
Crystal Structure Analysis ◽  
Magnetic Data ◽  
The Novel ◽  
Layer Arrangement ◽  
Dinuclear Iron

Herein we report the synthesis and characterization of three new dinuclear iron(II) complexes [FeII2(I4MTD)2](F3CSO3)4 (C1), [FeII2(I4MTD)2](ClO4)4 (C2) and [FeII2(I4MTD)2](BF4)4 (C3) based on the novel ligand (I4MTD = 2,5-bis{[(1H-imidazol-4-ylmethyl)amino]methyl}-1,3,4-thiadiazole). Magnetic susceptibility measurements and single-crystal structure analysis show that the iron(II) spin centers for all complexes are in the high spin state at high temperatures. While the magnetic data of air-dried samples confirm the [HS-HS] state for C1 and C2 down to very low temperature, for C3, a gradual spin crossover is observed below 150 K. The crystal structure of C3·THF at 100 K shows that a spin transition from [HS-HS] to an intermediate state takes place, which is a 1:1 mixture of discrete [HS-HS] and [LS-LS] molecules, as identified unambiguously by crystallography. The different SCO properties of C1–C3 can be attributed to crystal packing effects in the solid state.

scholarly journals A novel spin transition curve in [tris(2-picolylamine)Fe(II)]Cl2allyl solvate

2005 ◽  
Vol 61 (a1) ◽  
pp. c317-c317
Author(s):  
B. Vangdal ◽  
M. Hostettler ◽  
D. Chernyshov ◽  
K. W. Törnroos ◽  
H.-B. Bürgi
Keyword(s):  
Spin Transition ◽  
Transition Curve
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