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1.
Lab Anim ; 58(1): 52-64, 2024 Feb.
Article in English | MEDLINE | ID: mdl-37702462

ABSTRACT

To understand the epizootiologic characteristics of pathogens and opportunistic infections in one Beagle dog production colony and three research facilities, viruses and mycoplasma were detected in 1777 samples collected from Beagle dogs in China by polymerase chain reaction/reverse transcription polymerase chain reaction, and bacteria were isolated and identified by 16S rRNA sequence analysis. In addition, genotyping of the major circulating viruses was carried out by amplification of gene fragments and homology analysis. Canine coronavirus (CCoV), Escherichia coli, canine parvovirus (CPV), Bordetella bronchiseptica, Clostridium perfringens, Mycoplasma cynos, Klebsiella pneumoniae, Streptococcus canis, canine astrovirus (CaAstV), canine kobuvirus (CaKV), Pseudomonas aeruginosa, Proteus mirabilis, Macrococcus canis, Pasteurella canis, canine bocavirus (CBoV) and canine adenovirus (CAdV) were detected in the samples. Single, double, triple and quadruple infections accounted for 6.6%, 1.4%, 1.2% and 0.96% of samples, respectively. CCoV strains in 81 samples included three genotypes, CCoV-I, CCoV-IIa and CCoV-IIb, by analysis of S gene. The rate of single infection of CCoV-I, CCoV-IIa or CCoV-IIb was 19%, 38% or 7.4% respectively. The double and triple infection rates of CCoV were 32.8% and 2.5% respectively. All CPV strains in 36 samples belonged to CPV-2c. There were three amino acid differences in the Fiber protein of CAdV-positive sample QD2022, compared with the reference strain Toronto A26/61 and the vaccine strain YCA-18. These results suggest that CCoV and CPV are primary infectious agents, and that these two viruses were often identified in mixed infections, or coinfections alongside mycoplasma or other bacteria. These results will provide the basis for improvements in prevention and control of naturally occurring infectious diseases in Beagle dog production colonies and research facilities.


Subject(s)
Coronavirus Infections , Coronavirus, Canine , Dog Diseases , Parvovirus, Canine , Dogs , Animals , Coronavirus Infections/epidemiology , Coronavirus Infections/veterinary , RNA, Ribosomal, 16S/genetics , Dog Diseases/epidemiology , Polymerase Chain Reaction , China/epidemiology , Coronavirus, Canine/genetics , Parvovirus, Canine/genetics
2.
Phys Chem Chem Phys ; 25(36): 24883-24893, 2023 Sep 20.
Article in English | MEDLINE | ID: mdl-37681237

ABSTRACT

Pressure is a powerful way to modulate physical properties. Understanding the effect of pressure on the thermal transport properties of thermoelectric materials is of great importance for the efficient design and optimization of thermoelectric performance. In this work, based on first-principles calculations and phonon Boltzmann transport theory, we find that the lattice thermal conductivities of Ag-based chalcopyrites AgXY2 (X = Al, Ga, and In; Y = S, Se, and Te) are dramatically suppressed by applying pressure. The inherent distorted tetrahedral configuration together with highly delocalized p-orbital electrons promotes the formation of metavalent bonding. The fact of metavalent bonding with a single bonding electron and small electron transfer between neighboring atoms leads to soft low-frequency optical phonons. With the increase of pressure, the softening of acoustic and low-frequency optical phonons induces enhanced anharmonicity and scattering channels. Such strong acoustic-optical phonon coupling results in larger phonon scattering rates and thus lowers the lattice thermal conductivity. These findings not only help unveil the underlying physical mechanisms for the anomalous thermal transport behaviors under high pressure, but also pave the way for the pressure tuning of high-performance Ag-based thermoelectric materials.

3.
Phys Chem Chem Phys ; 24(35): 20891-20900, 2022 Sep 14.
Article in English | MEDLINE | ID: mdl-36043514

ABSTRACT

Zintl phase Mg3Sb2, which has ultra-low thermal conductivity, is a promising anisotropic thermoelectric material. It is worth noting that the prediction and experiment value of lattice thermal conductivity (κ) maintain a remarkable difference, troubling the development and application. Thus, we firstly included the four-phonon scattering processes effect and performed the Peierls-Boltzmann transport equation (PBTE) combined with the first-principles lattice dynamics to study the lattice thermal transport in Mg3Sb2. The results showed that our theoretically predicted κ is consistent with the experimentally measured, breaking through the limitations of the traditional calculation methods. The prominent four-phonon scatterings decreased phonon lifetime, leading to the κ of Mg3Sb2 at 300 K from 2.45 (2.58) W m-1 K-1 to 1.94 (2.19) W m-1 K-1 along the in (cross)-plane directions, respectively, and calculation accuracy increased by 20%. This study successfully explains the lattice thermal transport behind mechanism in Mg3Sb2 and implies guidance to advance the prediction accuracy of thermoelectric materials.

4.
Phys Chem Chem Phys ; 23(41): 23718-23729, 2021 Oct 27.
Article in English | MEDLINE | ID: mdl-34642727

ABSTRACT

Thermoelectric materials with excellent performance can efficiently and directly convert waste heat into electrical energy. In today's era, finding thermoelectric materials with excellent performance and adjusting the thermoelectric parameters are essential for the sustainable development of energy in the context of the energy crisis and global warming. Through first-principles calculations, we notice that two-dimensional (2D) orthogonal ScX2 (X = C and N) compounds show great potential in the field of thermoelectricity. Different from most materials containing C or N atoms, which are generally accompanied by high lattice thermal conductivity (TC), the 2D o-ScX2 exhibited a rather low and anisotropic lattice TC. The κ3L (the lattice thermal conductivity including the effect of three-phonon scattering and isotope scattering) of o-ScC2 along the X and Y directions are 2.79 W m-1 K-1 and 1.55 W m-1 K-1, and those of o-ScN2 are 1.57 W m-1 K-1 and 0.56 W m-1 K-1. By calculating the fourth-order interatomic force constants (IFCs), we obtain the κ3+4L with the additional four-phonon scattering effect. Our results clearly show that four-phonon scattering plays an important role in the TC of the two materials, the κ3+4L of o-ScC2 is only half of its κ3L. Furthermore, it can be noticed that the low lattice TCs of o-ScX2 (X = C and N) are the result of many factors, e.g., heavy atom doping, the strong anharmonicity caused by the vibration of Sc atoms in the out-of-plane direction and C(N) atoms in the in-plane direction, important four-phonon scattering and strongly polarized covalent bonds between X atoms and Sc atoms. Moreover, it is interesting to find that the thermal transport properties of o-ScX2 are led by a different phonon mechanism, e.g., the different TCs of o-ScC2 and o-ScN2 are determined by the anharmonic characteristic, and the harmonic characteristic plays a more important role in the anisotropy of o-ScX2 (X = C and N). In general, our research can be expected to provide important guidance for the application of o-ScX2 (X = C and N) in the thermoelectric field.

5.
Phys Chem Chem Phys ; 23(24): 13633-13646, 2021 Jun 23.
Article in English | MEDLINE | ID: mdl-34116567

ABSTRACT

With the ability to alter the inherent interatomic electrostatic interactions, modulating external electric field strength is a promising approach to tune the phonon transport behavior and enhance the thermoelectric performance of two-dimensional (2D) materials. Here, by applying an electric field (Ez = 0.1 V Å-1), it is predicted that an ultralow value of the lattice thermal conductivity (0.016 W m-1 K-1) at 300 K of 2D indium selenide (InSe) is nearly three orders of magnitude lower than that under an electric field of 0 V Å-1 (27.49 W m-1 K-1). Meanwhile, we calculated the variations in the electrical conductivities, electronic thermal conductivities, Seebeck coefficients, and figure of merit (ZT) of 2D InSe along with the carrier (hole and electron doping) concentrations under some representative electric fields. Owing to the smaller total thermal conductivity along the armchair and zigzag directions, p-type doped 2D InSe at Ez = 0.1 V Å-1 exhibits a larger ZT value (∼1.6) compared to the ZT value (∼0.1) without an electric field at room temperature. The peak ZT value (∼0.53) of the n-type 2D InSe at Ez = 0.1 V Å-1 is much higher than that without an electric field (∼0.02) at the same temperature. Our results pave the way for applying an external electric field to modulate the phonon transport properties and greatly promote the thermoelectric performance of some specific 2D semiconductor materials without altering their crystal structure.

6.
J Phys Chem A ; 125(1): 435-450, 2021 Jan 14.
Article in English | MEDLINE | ID: mdl-33355459

ABSTRACT

Prediction models of lattice thermal conductivity (κL) have wide applications in the discovery of thermoelectrics, thermal barrier coatings, and thermal management of semiconductors. However, κL is notoriously difficult to predict. Although classic models such as the Debye-Callaway model and the Slack model have been used to approximate the κL of inorganic compounds, their accuracy is far from being satisfactory. Herein we propose a genetic programming-based symbolic regression (SR) approach for finding analytical κL models and compare them with multilayer perceptron neural networks and random forest regression models using a hybrid cross-validation (CV) approach including both K-fold CV and holdout validation. Four formulae have been discovered by our SR approach that outperform the Slack formula as evaluated on our dataset. Through the analysis of our models' performance and the formulae generated, we found that the trained formulae successfully reproduce the correct physical law that governs the lattice thermal conductivity of materials. We also systematically show that currently extrapolative prediction over datasets with different distributions as the training set remains to be a big challenge for both SR and machine learning-based prediction models.

7.
Nanotechnology ; 32(2): 025709, 2021 Jan 08.
Article in English | MEDLINE | ID: mdl-33055376

ABSTRACT

Generally speaking, for materials with the same structure, the thermal conductivity is higher for lighter atomic masses. However, we found that the thermal conductivity of CaO is lower than that of CaS, despite the lighter atomic mass of O than S. To uncover the underlying physical mechanisms, the thermal conductivity of CaM (M = O, S, Se, Te) and the corresponding response to strain is investigated by performing first-principles calculations along with the phonon Boltzmann transport equation. For unstrained system, the order of thermal conductivity is CaS > CaO > CaSe > CaTe. This order remains unchanged in the strain range of -2% to 5%. When the compressive strain is larger than 2%, the thermal conductivity of CaO surpasses that of CaS and becomes the highest thermal conductivity material among the four compounds. By analyzing the mode-dependent phonon properties, the phonon lifetime is found to be dominant over other influential factors and leads to the disparate response of thermal conductivity under strain. Moreover, the changing trend of three-phonon scattering phase space is consistent with that of phonon lifetime, which is directly correlated to the phonon frequency gap induced by the LO-TO splitting. The variation of Born effective charge is found to be opposite for CaM. The Born effective charge of CaO decreases with tensile strain increasing, demonstrating stronger charge delocalization and lower ionicity, while the Born effective charges of CaS, CaSe, and CaTe show a dramatic increase. Such variation indicates that the bonding nature can be effectively tuned by external strain, thus affecting the phonon anharmonic properties and thermal conductivity. The difference of bonding nature is further confirmed by the band structure. Our results show that the bonding nature of CaM can be modulated by external strain and leads to disparate strain dependent thermal conductivity.

8.
Nanoscale ; 12(37): 19178-19190, 2020 Oct 07.
Article in English | MEDLINE | ID: mdl-32926048

ABSTRACT

Thermal anisotropy/isotropy is one of the fundamental thermal transport properties of materials and plays a critical role in a wide range of practical applications. Manipulation of anisotropic to isotropic thermal transport or vice versa is in increasing demand. However, almost all the existing approaches for tuning anisotropy or isotropy focus on structure engineering or materials processing, which is time and cost consuming and irreversible, while little progress has been made with an intact, robust, and reversible method. Motivated by the inherent relationship between interatomic interaction mediated phonon transport and electronic charges, we comprehensively investigate the effect of external electric field on thermal transport in two-dimensional (2D) borophene by performing first-principles calculations along with the phonon Boltzmann transport equation. Under external electric field, the lattice thermal conductivity of borophene in both in-plane directions first increases significantly to peak values with the maximum augmentation factor of 2.82, and the intrinsic anisotropy (the ratio of thermal conductivity along two in-plane directions) is boosted to the highest value of 2.13. After that, thermal conductivities drop down steeply and anisotropy exhibits oscillating decay. With the electric field increasing to 0.4 V Å-1, the thermal conductivity is dramatically suppressed to 1/40 of the original value at no electric field. More interestingly, the anisotropy of the thermal conductivity decreases to the minimum value of 1.25, showing almost isotropic thermal transport. Such abnormal anisotropic to isotropic thermal transport transition stems from the large enhancement and suppression of phonon lifetime at moderate and high strength of electric field, respectively, and acts as an amplifying or reducing factor to the thermal conductivity. We further explain the tunability of phonon lifetime of the dominant acoustic mode by an electron localization function. By comparing the electric field-modulated thermal conductivity of borophene with the dielectric constant, it is found that the screened potential resulting from the redistributed charge density leads to phonon renormalization and the modulation of phonon anharmonicity and anisotropy through electric field. Our study paves the way for robust tuning of anisotropy of phonon transport in materials by applying intact, robust, and reversible external electric field without altering their atomic structure and would have a significant impact on emerging applications, such as thermal management of nanoelectronics and thermoelectric energy conversion.

9.
Viruses ; 12(3)2020 03 19.
Article in English | MEDLINE | ID: mdl-32204363

ABSTRACT

Ostrich diseases characterized by paralysis have been breaking out in broad areas of China since 2015, causing major damage to the ostrich breeding industry in China. This report describes a parvovirus detected in ostriches from four different regions. The entire genomes of four parvovirus strains were sequenced following amplification by PCR, and we conducted comprehensive analysis of the ostrich parvovirus genome. Results showed that the length genomes of the parvovirus contained two open reading frames. Ostrich parvovirus (OsPV) is a branch of goose parvovirus (GPV). Genetic distance analysis revealed a close relationship between the parvovirus and goose parvovirus strains from China, with the closest being the 2016 goose parvovirus RC16 strain from Chongqing. This is the first report of a parvovirus in ostriches. However, whether OsPV is the pathogen of ostrich paralysis remains uncertain. This study contributes new information about the evolution and epidemiology of parvovirus in China, which provides a new way for the study of paralysis in ostriches.


Subject(s)
Evolution, Molecular , Genome, Viral , Parvoviridae Infections/virology , Parvovirus/physiology , Struthioniformes/virology , Animals , Base Sequence , Genetic Testing , Genomics/methods , Parvoviridae Infections/diagnosis , Phylogeny , Polymerase Chain Reaction
10.
Nanoscale ; 12(5): 3330-3342, 2020 Feb 06.
Article in English | MEDLINE | ID: mdl-31976500

ABSTRACT

By performing first-principles calculations combined with the Boltzmann transport equation, we report a comprehensive study of the thermal and thermoelectric properties of monolayer triphosphides InP3, GaP3, SbP3 and SnP3. Firstly, we studied the structure and phonon dispersion, and discussed the long-range atomic interactions by analyzing the second-order interatomic force constants (IFCs). Next, we predicted the corresponding thermal conductivities of monolayer InP3, GaP3, SbP3 and SnP3 at 300 K to be 0.64 W m-1 K-1, 3.02 W m-1 K-1, 1.04 W m-1 K-1 and 0.48 W m-1 K-1, respectively. To study the thermoelectric properties, the carrier mobility and electron relaxation time of the four materials were predicted by the deformation potential theory method and explained by analyzing their energy band structures. Then, the Seebeck coefficient, electrical conductivity and thermoelectric figure of merit (ZT) at different temperatures were calculated by using the Boltzmann transport equation with relaxation time approximation. Finally, we predicted the maximum ZT values of InP3, GaP3, SbP3 and SnP3 to be up to 2.6, 0.9, 1.9 and 3.7 at 300 K and up to 4.6, 1.6, 3.5 and 6.1 at 500 K, respectively. With ultra-low thermal conductivity and high thermoelectric performance, monolayer triphosphides are considered as potential candidates for thermoelectric materials.

11.
Phys Chem Chem Phys ; 22(4): 1911-1922, 2020 Jan 29.
Article in English | MEDLINE | ID: mdl-31912827

ABSTRACT

Manipulation of crystal symmetry is an important strategy to tune the thermoelectric performance. High-symmetry thermoelectric materials benefit from high band degeneracy. With first-principles calculations and Boltzmann transport theory, we systematically investigate the electronic and phononic transport properties of rhombohedral GeSe with higher symmetry. At optimized carrier concentrations, the maximum power factors are found to be 5.86 mW m-1 K-2 for the p-type and 4.45 mW m-1 K-2 for the n-type, respectively. The high p-type power factor originates from the highly degenerated L and Σ bands and small energy offset between them, while the n-type one results from the weak electron-phonon coupling. More importantly, rhombohedral GeSe possesses anisotropic and low lattice thermal conductivities of 3.58 W m-1 K-1 and 1.96 W m-1 K-1 at room temperature in the intralayer and interlayer directions, respectively, which is associated with the giant phonon anharmonicity driven by the resonant bonding. Combining the high power factor and low thermal conductivity, the predicted ZT values for p-type and n-type doping can reach 2.02 and 2.37 at 800 K. This study offers insights into the thermal and charge transport properties in rhombohedral GeSe, and demonstrates that both p-type and n-type GeSe are potential high-performance thermoelectric materials.

12.
Nanotechnology ; 31(11): 115701, 2020 Mar 13.
Article in English | MEDLINE | ID: mdl-31766046

ABSTRACT

Motivated by the experimental synthesis of peanut-shaped carbon nanotubes (PSNTs) that combine the novel features of fullerene and carbon nanotubes (CNTs), we study the thermal conductivity of a PSNT (1dp08) and its response to different strains by using non-equilibrium molecular dynamics simulations and lattice dynamics together with density functional theory. We find that the thermal conductivity of the PSNT is reduced by more than 90% as compared to that of CNTs, and remains almost the same when different strains applied, exhibiting very different behaviors from that of CNTs, where the thermal conductivity decreases monotonically with the increase of strain. Through phonon mode calculations, we show that the reduced phonon group velocity, phonon lifetime and the vibrational mismatch are responsible for the low thermal conductivity of the PSNT, and the insensitive response of thermal conductivity to strain is due to the insensitivity of its phonon density of states and group velocity to strain. These features endow the PSNT with the potential applications in thermal devices, and add new features to one-dimensional carbon nanomaterials going beyond conventional CNTs.

13.
ACS Appl Mater Interfaces ; 11(45): 42708-42714, 2019 Nov 13.
Article in English | MEDLINE | ID: mdl-31625728

ABSTRACT

Reliability and lifespan of highly miniaturized and integrated devices will be effectively improved if excessive accumulated heat can be quickly transported to heat sinks. In this study, both molecular dynamics (MD) simulations and experiments were performed to demonstrate that self-assembled monolayers (SAMs) have high potential in interfacial thermal management and can enhance thermal transport across the polystyrene (PS)/silicon (Si) interface, modeling the common polymer/semiconductor interfaces in actual devices. The influence of packing density and alkyl-chain length of SAMs is investigated. First, MD simulations show that the interfacial thermal transport efficiency of SAM is higher with high packing density. The interfacial thermal conductance (ITC) between PS and Si can be improved up to 127 ± 9 MW m-2 K-1, close to the ITC across the metal and semiconductor interface. At moderate packing density, the SAMs with less than eight carbon atoms in the alkyl chain show superior improvements over those with more carbons because of the assembled structure variation. Second, the time-domain thermoreflectance technique was employed to characterize the ITCs of a bunch of Al/PS/SAM/Si samples. C6-SAM enhances the ITC by fivefolds, from 11 ± 1 to 56 ± 17 MW m-2 K-1. The interfacial thermal management efficiency will weaken when the alkyl chain exceeds eight carbon atoms, which agrees with the ITC trend from MD simulations at moderate packing density. The relationship between the SAM morphology and interfacial thermal management efficiency is also discussed in detail. This study demonstrates the feasibility of molecular-level design for interfacial thermal management from both the theoretical calculation and experiment and may provide a new idea for improving the heat dissipation efficiency of microdevices.

14.
Phys Chem Chem Phys ; 21(28): 15647-15655, 2019 Jul 17.
Article in English | MEDLINE | ID: mdl-31268444

ABSTRACT

In this study, strain modulation of the lattice thermal conductivity of monolayer and bilayer penta-graphene (PG) at room temperature was investigated using first-principles calculations combined with the phonon Boltzmann transport equation. The thermal conductivities of both the monolayer and the bilayer PG exhibit a robust nonmonotonic up-and-down behavior under strain despite the effect of van der Waals (vdW) interactions, and the thermal conductivities of bilayer PG under strain are significantly reduced by up to 87%. Using phonon-level systematic analysis, the variation of thermal conductivity with the increasing strain was determined by increasing the phonon lifetime in specific phonon modes, and that with the reduction of strain was determined by the decrease of both phonon group velocity and phonon lifetime. Moreover, bilayer PG shows an unexpectedly different response to strain when compared with monolayer PG, and a significantly larger reduction (>60%) in the thermal conductivity of bilayer PG is achieved when the strain reaches 10% because the interlayer interactions enhance the phonon anharmonicity of the phonon modes of ultra-low frequency. Our study shows that bilayer PG will have tremendous opportunities for application in thermal management and two-dimensional nanoscale electronic devices owing to its largely tunable thermal conductivity.

15.
Sci Rep ; 9(1): 9490, 2019 Jul 01.
Article in English | MEDLINE | ID: mdl-31263221

ABSTRACT

In this paper, we systematically investigate the effect of hydrostatic pressure on the phononic and electronic transport properties of orthorhombic p-type GeSe using first-principles based Boltzmann transport equation approach. It is found that the lattice thermal conductivities along the a and c directions increase with pressure, whereas it experiences a decrease along the b direction. This anomalous pressure dependent lattice thermal conductivity is attributed to the combined effect of enhanced phonon group velocity and reduced phonon lifetime. Additionally, the optical phonon branches have remarkable contributions to the total lattice thermal conductivity. The electronic transport calculations indicate that the Seebeck coefficient undergoes a sign change from p-type to n-type along the a direction under pressure, and a dramatic enhancement of the power factor is observed due to the boost of electrical conductivity. The predicted ZT values along the a, b, and c directions are 1.54, 1.09, and 1.01 at 700 K and 8 GPa, respectively, which are about 14, 7.3, and 1.9 times higher than those at zero pressure at experimental carrier concentration of ~1018 cm-3. Our study is expected to provide a guide for further optimization of the thermal and charge transport properties through hydrostatic pressure.

16.
Phys Chem Chem Phys ; 21(11): 6011-6020, 2019 Mar 13.
Article in English | MEDLINE | ID: mdl-30810132

ABSTRACT

In this paper, the interfacial thermal transport properties at the interfaces between the cubic compounds of boron with selected group V elements (BP, BN, BAs and BSb) and various substrates (Si, 6H-SiC and 3C-SiC) were studied by first-principles calculations. Systematic analysis of the effect of crystal information on interfacial thermal transport is performed based on the study of phonon density of states, atomic mass, crystal structure and spectral heat flux, respectively. The results show that the overlap of the phonon density of states of the two interface materials is related to the interfacial thermal conductance. Other crystal information, the atomic mass and lattice constant, which cannot directly reflect the trend of interfacial thermal conductance, can only play a predictive role. Further deep insight suggests that the interfacial thermal conductance also depends strongly on the phonon thermal transport characteristics of different materials and the frequency-dependent spectral heat flux. The results from this work unveil the fact that Si and SiC as the substrate materials do not have absolute superiority or inferiority, depending on the matching rate of many factors of the two materials at the interfaces. This study explores the phonon-level mechanisms for interfacial thermal transport between compounds of boron with group V elements and Si/SiC substrates and provides effective ways to improve the interfacial thermal transport in silicon based modern micro/nano-electronic devices.

17.
Phys Chem Chem Phys ; 21(1): 468-477, 2018 Dec 19.
Article in English | MEDLINE | ID: mdl-30534676

ABSTRACT

In this paper, first-principles calculations along with the phonon Boltzmann transport equation are used to study the strain- and size-dependent thermal conductivity of monolayer WSe2. The thermal conductivity of monolayer WSe2 is primarily contributed by the acoustic phonons and decreases with tensile strain due to the reduction in both the group velocity and phonon lifetime. Shrinking the system size also restricts the thermal conductivity significantly by ruling out the contributions of long mean free path phonons. The rate of decrease in thermal conductivity with tensile strain is found to be size dependent, which is attributed to the competition between the phonon-phonon scattering and the phonon-boundary scattering. The decreasing trend of the thermal conductivity of monolayer WSe2 through tensile strain paves the way for high-efficiency thermoelectric materials combining the strain-tuned electronic structure.

18.
Phys Chem Chem Phys ; 20(48): 30331-30339, 2018 Dec 12.
Article in English | MEDLINE | ID: mdl-30488067

ABSTRACT

In this paper, the variation of the lattice thermal conductivity of GaAs under pressure within the range of 0-20 GPa at room temperature is investigated by combining first-principles calculations with an iterative solution of the phonon Boltzmann transport equation. Firstly, we calculated the lattice thermal conductivity of GaAs at 12 GPa, which increases by more than 37% in comparison with that under atmospheric pressure. The detailed analysis of phonon heat transport properties shows that the pressure contributes to increased phonon group velocity coupled with decreased phonon relaxation time, resulting in the pressure-induced nonlinear increase of the thermal conductivity of zinc blende GaAs. Besides, not only the structure but also the phonon heat transport properties of GaAs transform from isotropic to anisotropic beyond the phase transition pressure. This study provides a quantitative understanding of the thermal conductivity of GaAs considering pressure-induced phase transitions and highlights the importance of pressure in tuning lattice thermal conductivity, especially in pressure-induced phase change materials.

19.
RSC Adv ; 8(64): 36754-36760, 2018 Oct 26.
Article in English | MEDLINE | ID: mdl-35558927

ABSTRACT

Long-term operation of microbial fuel cells (MFCs) results in an electrochemical activity decline by the degradation of the anodic biofilm. In this work, an alkaline soaking treatment is proposed as an efficient and simple method for anode regeneration. The alkaline treatment was employed in a used carbon-brush anode, and its performance was compared with those of two other traditional treatment methods, i.e. air drying and carbonization. Among all the treated MFC anodes, the one treated by alkaline soaking exhibited the highest recovery rate. A series of tests including a start-up process, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and MFC performance were performed. The results show that alkaline soaking can modify the carbon fiber by introducing carboxyl groups onto the carbon surface and completely remove the aged biofilm, demonstrating that the alkaline treatment of used anodes is a practically effective method for the performance recovery of MFCs.

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