The use of magnetic shape memory alloys (MSMA
s
) in manufacturing industry has increased significantly in recent years. This is mainly due to their great interest in their potential applications in ...smart devices, because of the reversible distortions suffered. The well-known example of these combinations is the Heusler type. A review is given of experimental works concerning the examination of magnetic field, structural phase transitions, and the magnetocaloric impact in Heusler Ni–Mn–X (X = In, Sn, Sb) and Ni–Co–Mn–Y (Y = In, Sn, Sb) alloys. This type of compounds has excellent properties, for example, the presence of coupled magnetostructural (coïncident magnetic and martensitic transitions) and metamagnetostructural phase transitions (coïncident metamagnetic (ferromagnetic-antiferromagnetic) and martensitic transitions), the magnetocaloric impact (MC), and the large magnetoresistance change (MR). The conceivable difficulties and remaining problems are briefly discussed.
In this study, three shape memory alloys, Mn
50
Ni
50-x
Sn
x
(
x
= 5, 7.5, and 10), were elaborated by melt spinning. The structure, microstructure, and magnetic properties of these alloys were ...carried out by X-ray diffraction, scanning electron microscopy, and physical property measurement system, respectively. The experimental results showed that the increase in Sn ratio caused a phase transformation. The structure of the martensite phase (for
x
= 5 and 7.5) was seen as a monoclinic 14 M structure, while the structure of the austenite phase (for
x
= 10) was observed as a cubic L2
1
structure. We revealed that the addition of Sn led to an almost linear decrease in martensitic transition temperatures, due to the decrease in valence electron ratio (e/a). We explored that for
x
= 10, the martensitic transition that occurs from the ferromagnetic austenite to weakly magnetic martensite was realized due to the strong magnetostructural coupling in this alloy. Also, it is found that there is a slight decrease in temperatures and a slight increase in the thermal hysteresis range, due to the increase in the magnetic field. While, for
x
= 7.5 and
x
= 5, they have the transitions at high temperatures above 400 and 550 K, respectively. This fact might limit these alloys in their applications. So, the present results indicate that the amount of Sn content in the MnNiSn alloys plays an important role to modify the structural and magnetic properties.
Faster-growing cells must synthesize proteins more quickly. Increased ribosome abundance only partly accounts for increases in total protein synthesis rates. The productivity of individual ribosomes ...must increase too, almost doubling by an unknown mechanism. Prior models point to diffusive transport as a limiting factor but raise a paradox: faster-growing cells are more crowded, yet crowding slows diffusion. We suspected that physical crowding, transport, and stoichiometry, considered together, might reveal a more nuanced explanation. To investigate, we built a first-principles physics-based model of Escherichia coli cytoplasm in which Brownian motion and diffusion arise directly from physical interactions between individual molecules of finite size, density, and physiological abundance. Using our microscopically detailed model, we predicted that physical transport of individual ternary complexes accounts for ~80% of translation elongation latency. We also found that volumetric crowding increases during faster growth even as cytoplasmic mass density remains relatively constant. Despite slowed diffusion, we predicted that improved proximity between ternary complexes and ribosomes wins out, illustrating a simple physics-based mechanism for how individual elongating ribosomes become more productive. We speculate that crowding imposes a physical limit on growth rate and undergirds cellular behavior more broadly. Unfitted colloidal-scale modeling offers systems biology a complementary "physics engine" for exploring how cellular-scale behaviors arise from physical transport and reactions among individual molecules.
Ribosomes are the factories in cells that synthesize proteins. When cells grow faster, there are not enough ribosomes to keep up with the demand for faster protein synthesis without individual ribosomes becoming more productive. Yet, faster-growing cells are more crowded, seemingly making it harder for each ribosome to do its work. Our computational model of the physics of translation elongation reveals the underlying mechanism for how individual ribosomes become more productive: proximity and stoichiometry of translation molecules overcome crowding. Our model also suggests a universal physical limitation of cell growth rates.
In this study, Fe
75
Si
12
Ti
6
B
7
and Fe
73
Si
15
Ti
5
B
7
(wt. %) alloy powders were synthesized from pure elemental powders by a mechanical alloying (MA) method under argon atmosphere. The ...evolution in particles morphology, chemical composition, crystalline structure, magnetic and hyperfine proprieties of the mixture elements during MA(0–80 h) was investigated by scanning electron microscopy attached with energy-dispersive spectroscopy, X-ray diffraction (XRD), vibrating sample magnetometer and Mössbauer spectroscopy (MS). The Rietveld refinement of the XRD pattern of the samples milled 5 h shows the formation of several structures: Fe
3
Si,
α
-Fe nanostructured, Fe
2
Ti and Fe
2
B, in addition, that the structure became much more amorphous together with increasing milling time at 80 h. The thermal stability of powders milled was characterized by differential scanning calorimetry (DSC). The annealing of samples milled 80 h shows that the crystallization of the amorphous phases and the activation energy determined by using Kissinger's equation was 462.23 ± 16.11 kJ mol
−1
and 798.43 ± 16.12 kJ mol
−1
for the Fe
73
Si
15
Ti
5
B
7
and Fe
75
Si
12
Ti
6
B
7
, respectively. Moreover, the results from XRD and DSC for 80 h of milling were approved by the Mössbauer spectroscopy, and the spectra revealed that the sample Fe
73
Si
15
Ti
5
B
7
is fully amorphous, but the sample Fe
75
Si
12
Ti
6
B
7
still contains some of Fe with a 2.8% fraction non- detected by XRD. The saturation magnetization (Ms) and coercivity values were of about 151 emu/g, 38.5 G for Fe
73
Si
15
Ti
5
B
7
and 171.6 emu/g, 35 G for Fe
75
Si
12
Ti
6
B
7
, respectively, after 80 h of milling.
The crystals of the family of alkylammonuim tetrachloridocuprate (II), (C5H7N2)2CuCl4H2O, have been grown, structurally characterized and their vibrational as well as optical properties been studied. ...A preliminary single crystal X-ray diffraction structural analysis has revealed that the title compound belongs to the monoclinic system with space group C2/c. Its unit cell dimensions are: a=8.454 (2)Å, b=14.279 (2)Å, c=14.363 (3)Å, β=95.813 (4)°, with Z=4 and its crystal structure was determined and refined down to R1=0.029 and wR2=0.080. The crystal lattice is composed of discrete CuCl42− tetrahedra surrounded by 4-aminopyridinium cations and water molecules which are interconnected by means of hydrogen bonding contacts N–H…Cl, O–H…Cl and N–H…O. Furthermore, the room temperature IR and Raman spectra of the title compound were recorded and analyzed. The optimized molecular structure and the vibrational spectra were calculated by the density functional theory (DFT) method using the B3LYP function. The organic–inorganic hybrid crystal thin film can be easily prepared by spin-coating method from the ethanol solution of the (C5H7N2)2CuCl4H2O perovskite and it showed characteristic absorptions of CuCl-based layered perovskite centered at 288 and 400nm, as well as the photoluminescence peak at around 443nm. The unaided-eye-detectable blue luminescence emission comes from the excitonic transition in the CuCl4 anions.
•A new hybrid compound (C5H7N2)2CuCl4H2O was synthesized.•Vibrational properties were studied by IR and Raman spectroscopy and examined theoretically using the DFT/B3LYP/LanL2DZ level of theory.•The UV–vis spectrum shows two absorption peaks at 288 and at 400nm.•This compound show a strong blue emission at 443nm.
With the growing emphasis on decreasing the accumulation of the used tyres in land fills, there has been significant scientific and technological interest to provide with solutions to their recovery ...and reuse. A new composite material based on reused tyre powder as reinforcement and recycled high-density polyethylene as matrix was studied in this work. The effect of chemical acidic pretreatments performed on the rubber and of the particle size on the behavior of the composite material were evaluated. Powder of reused tyres resulting from industrial grinding processes was separated by sieving in three particle size categories: below 200 μm, between 200-500 μm and over 500 μm. Pretreatments using H₂SO₄, HNO₃, or a 50% mix of H₂SO₄ and HNO₃ were carried out over the rubber before composite preparation. Mechanical tensile properties were evaluated to determine the effect of particle size and acid pretreatments on composite properties. Fracture surfaces of composite samples were also evaluated by scanning electron microscopy. Overall, all pretreatments improve the mechanical behavior of the obtained materials. This improvement is attributed to the development of a surface of the rubber, more suitable for mechanical adhesion. The effect of the particle size has a stronger influence in the properties of the material than the acidic pretreatments.
We outline the microstructural, martensitic transformation and magnetic properties of Heusler alloys with starting compositions Ni
50Mn
37Sn
13, Ni
50Mn
36In
14, and Mn
50Ni
40In
10, produced by melt ...spinning. The ribbons were obtained in argon environment at a high wheel linear speed of 48
m
s
−1 (typical dimensions: 1.2–2.0
mm in width, 4–12
mm in length, and 7–12
μm in thickness). EDS microanalysis showed that the resulting average elemental chemical composition is slightly shifted with respect to the starting one. Ribbons are fully crystalline and tend to show a highly ordered columnar-like microstructure with grains running through the entire ribbon thickness; the larger dimension of the grains is perpendicular to the ribbon plane. As-spun alloys were single-phase with ferromagnetic bcc
L2
1 austenite as high-temperature parent phase. At low temperatures austenite transforms into a structurally modulated martensite with a lattice symmetry that depends on the system (7 M orthorhombic for Ni
50Mn
37Sn
13, 10 M monoclinic for Ni
50Mn
36In
14, and 14 M monoclinic for Mn
50Ni
40In
10). Magnetization isotherms measured in the temperature interval where martensite thermally transforms into austenite confirmed the occurrence of field-induced reverse martensitic transition in the alloys studied.
The effect of cobalt doping on martensitic transformations and the magnetic properties of Ni50−xCox Mn37Sn13 (x = 1, 2, 3) magnetic shape memory alloys obtained by melt spinning in the form of ...ribbons is studied. The crystallographic structure of all of the ribbons at room temperature is austenite cubic L21. SEM micrographs indicate the formation of textured ribbons with columnar grains growing up perpendicular to the ribbon plane. For all of the ribbons, DSC cyclic scans reveal the martensitic transformation on cooling and the reverse austenitic transformation upon heating below room temperature. In addition, they indicate that the martensitic transformation temperatures decrease with an increasing cobalt content.
Thermomagnetic curves reveal the coexistence of AFM and FM exchange interactions at low temperatures. Likewise, the magnetization change (ΔM) between the martensite and austenite phase, as well as the austenite Curie temperature (TCA), increase with increasing cobalt content in the ribbons. Structural transformations are also sensitive to the external applied magnetic field. This fact suggests that the structural transformation temperatures of the ribbons could be tuned to the desired functional temperature by controlling the cobalt amount through the replacement of Ni as well as by changing the applied magnetic field, which could lead to an enhancement of the magnetic properties.
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•Ni50−xMn37Sn13Co (x = 1, 2, 3) ribbons were obtained by melt spinning process.•Cobalt reduces martensite and austenite transformation temperatures of the ribbons.•The magnetic properties (ΔM, TC) increase with greater cobalt content.•Structural transformations are sensitive to the external applied magnetic field.
This study was conducted on the reduction reaction of the azo dye Reactive Black 5 by means of the Mn
85
Al
15
particles prepared by melt-spinning and ball-milling processes. The morphology, the ...surface elementary composition and the phase structure of the powders were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. The degradation efficiency of the ball milled powder was measured by using an ultraviolet-visible absorption spectrophotometer and the collected powder was analyzed by means of Fourier transform infrared spectroscopy technique to characterize the functional groups in the extract. The degradation of Reactive Black 5 and the analysis of the aromatic by-products were investigated by high performance liquid chromatography coupled with tandem mass spectrometry. The ball-milled powder shows higher degradation efficiency and the Reactive Black 5 solution was completely decolorized after 30 min. The degradation kinetics and the formation by-products depend on the pH and temperature of the solution. The analyses of the extracted product confirmed the cleavage of the (-N&z.dbd;N-) bonds. Our findings are expected to pave the way for a new opportunity with regard to the functional applications of nanostructured metallic particles.
This study was conducted on the reduction reaction of the azo dye Reactive Black 5 by means of the Mn
85
Al
15
particles prepared by melt-spinning and ball-milling processes.
We report on the crystal structure, microstructure and magnetic properties of Ni nanoparticles (NPs), with an average diameter of around 40nm, produced by hydrothermal method. A series of Ni powders ...was synthesized at relatively low temperature (140°C) by varying the NaOH concentration. The crystal structure, microstructure and magnetic properties were investigated by means of XRD, MEB coupled to EDX and VSM magnetometry. The XRD patterns show Bragg reflections corresponding to Ni with face centred cubic (fcc) crystal structure. EDX spectra confirm the purity of Ni powders. Moreover, the SEM micrographs show that the Ni-NPs are agglomerated forming entities of 1–5μm in average size with different morphologies that change as the NaOH concentration increases. While those entities exhibit a flower-like form at the lowest concentration, a dendritic shape appears for the highest one. The room temperature values for the coercive field (<200Oe) and saturation magnetization (≈52Am2/kg) were obtained from the magnetic hysteresis loops. We discuss about the influence of the particle morphology on the magnetic behaviour.
•High purity Ni nanoparticles have been elaborated by hydrothermal method under the presence of sodium hydroxide with different concentrations.•The variation of the NaOH concentration seems to be irrelevant for the NP size, but plays an important role in the morphology.•The shape of Ni nanoparticles changes from spherical cores to flower-like entities and then to dendritic ones as the NaOH concentration increases.•The coercive field depends on the shape of nanoparticles.
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