Magnetic nanoparticles (MNPs) have drawn a lot of interest due to their special qualities, which include large surface area, super para magnetism, and ease of functionalization. These qualities make MNPs perfect for use in electronics, biomedicine, and environmental remediation. This article delivers a critical and nuanced overview, integrating diverse perspectives to advance a deeper understanding of MNP synthesis, characterization, and applications. Typical synthesis methods are covered, such as sol-gel, hydrothermal, thermal decomposition, and co-precipitation. This paper also covers important characterization methods for evaluating the structural and magnetic properties of MNPs, including vibrating sample magnetometry (VSM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The many uses of MNPs in areas such as environmental pollution control, bio-sensing, and biomedicine are also covered. In addition to offering mechanistic insight into the synthesis, functionalization, and use of MNPs, this thorough analysis also describes the limitations and future possibilities.
AbstractMagnetic refrigeration utilizes the magnetocaloric effect of a magnetic material, whose temperature changes according to the change of magnetic field strength. It is regarded as an eco-friendly refrigeration technology in that it uses magnetic materials as refrigerants instead of CFC, HCFC, and HFC refrigerants used in vapor compression refrigeration. It is also regarded as an energy-efficient refrigeration technology in that it does not use noisy and power-consuming compressors. This paper presents thermodynamic analysis on a magnetic refrigeration system using experimental results obtained from a magnetic refrigeration apparatus. The magnetic refrigeration apparatus was built using two sets of concentric Halbach cylinders consisting of permanent magnet segments. Specifically the coefficient of performance (COP) of the magnetic refrigeration system was calculated using the energy removed from the working fluid across an AMR bed and the work input to run electric motors.
Ultra-short pulse propagation in nonlinear NRM has been investigated where a wide class of solutions for bright and dark solitons has been analyzed for distinct parameter ranges. Here the pulse propagation in nonlinear meta-material has been analytically by solving the nonlinear Schrödinger's equation (NLSE) in composite media expressing frequency dispersion in the dielectric permittivity (ε) and the magnetic permeability (µ). The solutions are exactly shown to be of trigonometric & localized types. The analytical and simulation based result has been utilized to study the intensity variation in case of a nonlinear meta-material which typically behaves as a negative refractive medium (NRM), for which both ε and µ exhibit frequency dispersion and are negative in nature. The peak of the pulse-intensity curve slowly decreases as the frequency increases towards the magnetic plasma frequency. The stability of the solitonic solutions has also been established.
Abstract. The present work comprises the systematic computational chemical findings on Chlorofullerene (C60Cl6). The molecular structure of C60Cl6 was optimized by density function theory (DFT)/B3LYP model of 6-31G(d,p) basis set using Gaussian 09 program. The infrared and Raman spectra were simulated and assigned for C60Cl6 molecule. Carbon – chlorine stretching vibrations are found to be in the range 150-900 cm-1 and the chains are strongly affected with the radial vibrations of the carbon sphere. The optimized geometries at ground-state of the molecules are calculated without any geometrical restriction, except those enforced by symmetry and the molecules are found to be minima on their respective potential energy surfaces. The optimized structures have been subjected to Gauge including atomic orbital (GIAO), the chemical shielding tensors using B3LYP/6-31G(d,p) in solvent phase with the aim of calculating 13C chemical shift values with respect to trimethylsilane (TMS) as computational reference. Molecular acuteness and stability were investigated using the Frontier molecular orbitals (FMO) analysis. The molecular electrostatic potential (MEP) mapping provides a valuable information regarding the net electrostatic effect produced by net charge distribution of the molecule. Chlorofullerenes are considered to be promising compounds for the investigation of biological action which show pronounced anti-HIV action and low toxicity. Hence, these results set goal in scheming the biocompatible molecules which will be useful in the field of carbon nano medicine and drug delivery application.
I summarize recent results, obtained with E. Dernier, K. Park, A. Polkovnikov, M. Vojta, and Y. Zhang, on spin and charge correlations near a magnetic quantum phase transition in the cuprates. Static charge order coexisting with dynamic spin correlations has recently been observed around vortices in slightly overdoped Bi2Sr2CaCu2O8+δ (J. E. Hoffman et al., Science 295, 466 (2002)), and neutron scattering experiments have measured the magnetic field dependence of static spin order in the underdoped regime in La2-δSrδCuO4 (B. Lake et al., Nature 415, 299 (2002)) and LaCuO4+y (B. Khaykovich et al. cond-mat/0112505). Our predictions provide a semi-quantitative description of these observations, with only a single parameter measuring distance from the quantum critical point changing with doping level. These results suggest that a common theory of competing spin, charge and superconducting orders provides a unified description of all the cuprates.
We extend the model of rational bubbles of Blanchard and of Blanchard and Watson to arbitrary dimensions d: a number d of market time series are made linearly interdependent via d times d stochastic coupling coefficients. We first show that the no-arbitrage condition imposes that the non-diagonal impacts of any asset i on any other asset j different from i has to vanish on average, i.e., must exhibit random alternative regimes of reinforcement and contrarian feedbacks. In contrast, the diagonal terms must be positive and equal on average to the inverse of the discount factor. Applying the results of renewal theory for products of random matrices to stochastic recurrence equations (SRE), we extend the theorem of Lux and Sornette (cond-mat/9910141) and demonstrate that the tails of the unconditional distributions associated with such d-dimensional bubble processes follow power laws (i.e., exhibit hyperbolic decline), with the same asymptotic tail exponent mu
In a previous paper (cond-mat/0106554) we showed the existence of two new zero-temperature exponents (\lambda and \theta') in two dimensional Gaussian spin glasses. Here we introduce a novel low-temperature expansion for spin glasses expressed in terms of the gap probability distributions for successive energy levels. After presenting the numerical evidence in favor of a random-energy levels scenario, we analyze the main consequences on the low-temperature equilibrium behavior. We find that the specific heat is anomalous at low-temperatures c ~ T**\alpha with \alpha=-d/\theta' which turns out to be linear for the case \theta'=-d.
We report further findings on the size distribution of the largest neutral segments in a sequence of N randomly charged monomers [D. Ertas and Y. Kantor, Phys. Rev. E53, 846 (1996); cond-mat/9507005]. Upon mapping to one--dimensional random walks (RWs), this corresponds to finding the probability distribution for the size L of the largest segment that returns to its starting position in an N--step RW. We primarily focus on the large N, \ell = L/N << 1 limit, which exhibits an essential singularity. We establish analytical upper and lower bounds on the probability distribution, and numerically probe the distribution down to \ell \approx 0.04 (corresponding to probabilities as low as 10^{-15}) using a recursive Monte Carlo algorithm. We also investigate the possibility of singularities at \ell=1/k for integer k.
We note that data on Si/SiGe heterostructures, reported in the Comment of Ismail et al. (cond-mat/9707061) on our recent Letter (cond-mat/9608101), are insufficient to establish the claim for a transition to a metallic phase.
This is a Reply to the Comment of S.R. White and D.J. Scalapino [cond-mat/9907243] on our recent paper ``Stripes and the t-J Model'' [Physical Review Letters 83, 132 (1999) and cond-mat/9812022].
In a comment on my recent manuscript on the pi-particle [cond-mat/9705049], Demler et al. [cond-mat/9705191] argued that there is a correction to the chemical potential which enters the expression for the energy of the pi-particle given in [Demler and Zhang, Phys. Rev. Lett. 77, 4126 (1995)]. This is shown to be incorrect. I further offer an interpretation for the low-energy resonances observed by Meixner et al. [cond-mat/9701217] in the pi-pi correlation function in a finite-size Hubbard cluster at low electron densities.
In a series of papers we combined the Bethe ansatz with a kinetic (Boltzmann) equation in order to compute exactly transport properties in a Luttinger liquid with an impurity. In a recent comment [cond-mat/9708163], Skorik claimed that while our results were correct in linear response, there was a ``serious flaw'' in our calculation at finite voltage. We explain here why Skorik's arguments are inappropriate, and that there is no flaw in our work [cond-mat/9408068; cond-mat/9505031; cond-mat/9503172].
Reply to the comment by D.N. Aristov and A.G. Yashenkin (cond-mat/9612245) on PRL by Balatsky and Salkola (Phys. Rev. Lett., V76, 2386, (1996), cond-mat/9602034).
We reply the comment made by Caracciolo et al. (cond. mat./0305213) to our work "Dynamic behavior of anisotropic non-equilibrium driving lattice gases", cond-mat/021041.
The paper is withdrawn by the author, because it is superseded by cond-mat/0303357. The paper is withdrawn by the author becuse it is superseded by cond-mat/0303357. ∗e-mail uwe.krey@physik.uni-regensburg.de 1