Technical structure of the global nanoscience and nanotechnology literature

Text mining was used to extract technical intelligence from the open source global nanotechnology and nanoscience research literature. An extensive nanotechnology/nanoscience-focused query was applied to the Science Citation Index/Social Science Citation Index (SCI/SSCI) databases. The nanotechnology/nanoscience research literature technical structure (taxonomy) was obtained using computational linguistics/document clustering and factor analysis. The infrastructure (prolific authors, key journals/institutions/countries, most cited authors/journals/documents) for each of the clusters generated by the document clustering algorithm was obtained using bibliometrics. Another novel addition was the use of phrase auto-correlation maps to show technical thrust areas based on phrase co-occurrence in Abstracts, and the use of phrase–phrase cross-correlation maps to show technical thrust areas based on phrase relations due to the sharing of common co-occurring phrases. The ∼400 most cited nanotechnology papers since 1991 were grouped, and their characteristics generated. Whereas the main analysis provided technical thrusts of all nanotechnology papers retrieved, analysis of the most cited papers allowed their characteristics to be displayed. Finally, most cited papers from selected time periods were extracted, along with all publications from those time periods, and the institutions and countries were compared based on their representation in the most cited documents list relative to their representation in the most publications list.     

The structure and infrastructure of the global nanotechnology literature

Text mining is the extraction of useful information from large volumes of text. A text mining analysis of the global open nanotechnology literature was performed. Records from the Science Citation Index (SCI)/Social SCI were analyzed to provide the infrastructure of the global nanotechnology literature (prolific authors/journals/institutions/countries, most cited authors/papers/journals) and the thematic structure (taxonomy) of the global nanotechnology literature, from a science perspective. Records from the Engineering Compendex (EC) were analyzed to provide a taxonomy from a technology perspective.

• The Far Eastern countries have expanded nanotechnology publication output dramatically in the past decade.
• The Peoples Republic of China ranks second to the USA (2004 results) in nanotechnology papers published in the SCI, and has increased its nanotechnology publication output by a factor of 21 in a decade.
• Of the six most prolific (publications) nanotechnology countries, the three from the Western group (USA, Germany, France) have about eight percent more nanotechnology publications (for 2004) than the three from the Far Eastern group (China, Japan, South Korea).
• While most of the high nanotechnology publication-producing countries are also high nanotechnology patent producers in the US Patent Office (as of 2003), China is a major exception. China ranks 20th as a nanotechnology patent-producing country in the US Patent Office.

     

Exceptionally high cavitation erosion and corrosion resistance of a high entropy alloy

Cavitation erosion and corrosion of structural materials are serious concerns for marine and offshore industries. Durability and performance of marine components are severely impaired due to degradation from erosion and corrosion. Utilization of advanced structural materials can play a vital role in limiting such degradation. High entropy alloys (HEAs) are a relatively new class of advanced structural materials with exceptional properties. In the present work, we report on the cavitation erosion behavior of Al_0.1CoCrFeNi HEA in two different media: distilled water with and without 3.5 wt% NaCl. For comparison, conventionally used stainless steel SS316L was also evaluated in identical test conditions. Despite lower hardness and yield strength, the HEA showed significantly longer incubation period and lower erosion-corrosion rate (nearly 1/4th) compared to SS316L steel. Enhanced erosion resistance of HEA was attributed to its high work-hardening behavior and stable passivation film on the surface. The Al_0.1CoCrFeNi HEA showed lower corrosion current density, high pitting resistance and protection potential compared to SS316L steel. Further, HEA showed no evidence of intergranular corrosion likely due to the absence of secondary precipitates. Although, the degradation mechanisms (formation of pits and fatigue cracks) were similar for both the materials, the damage severity was found to be much higher for SS316L steel compared to HEA.     

Enhancements in 3D dosimetry measurement using polymer gel and MRI

The effects of varying the concentrations of cross-linker N, $N^{\prime }$-methyelene-bis-acrylamide (BIS) from 2% to 4%, and 2-hydroxyethylacrylate (HEA) monomer from 2% to 4% at 5% gelatin on the dose response of BIS–HEA–gelatin (BHEAG) aqueous polymer gel dosimeters have been studied using magnetic resonance imaging (MRI) for relaxation rate ($R_2)$ of water proton. The dosimeters were irradiated with ⁶⁰Co teletherapy $\gamma$-ray source at a constant dose rate, receiving doses up to 30 Gy. The radiation polymerization occurs and increases with increasing initial dose. $R_2$ is found to decrease mono-exponentially with depth inside the polymer gel and depend strongly upon the initial concentrations of co-monomers (HEA and BIS). Dose–depth map for BHEAG gel was determined for different concentrations of co-monomer (HEA and BIS). The percentage dose depth was also evaluated which leads to a good agreement with the ionization chamber measurements.     

Bibliometric analysis of core journals which publish articles of physical therapy on aging

Objective. Increase in population''s longevity has led to considerable efforts worldwide on physical therapy aging research. The aim of this study is to identify which are the main scientific journals, as well as the most productive authors, institutions and keywords related to the journals, that have published about physical therapy and aging. Methods. Original articles published from 1990 to 2014 were retrieved from the bibliographic database Science Citation Index Expanded of Web of Science Core Collection. After standardization of the bibliographic information, a series of bibliometric indicators was obtained regarding authors, institutions, citation and keywords of the core journals using bibliometric software. The PAJEK network analysis program was used for graphic representation. Results. A total of 2,237 original articles are included in this analysis. The number of identified journals is 573, with an average growth of publishing journals throughout the studied period of 9.41%. Bradford''s distribution shows 12 core journals, out of which 41.67% have published constantly all throughout the 25-year period, being the most productive one Physical Therapy. Fritz, Julie M is the most productive author, and University of Sydney the most productive institution. The keyword exercise is used in an outstanding way. Conclusions. The productivity trends provided an indication of the greater scientific interest of physical therapy in aging as a line of research. Collectively, the data indicated that physical therapy-specific journals are being consolidated but non-specific are still a significant research source, and that a fundamental element of their research includes exercise and movement.     

国家自然科学基金工程热物理与能源利用学科研究方向与关键词修订

2021年国家自然科学基金委员会工程与材料科学部工程热物理与能源利用学科对学科代码下的研究方向和关键词进行了梳理和修订,调整了学科资助布局,合并了相近的研究方向,删除了不恰当的研究方向,增加了反映新趋势的研究方向,精炼了各研究方向下的关键词,使研究方向和关键词更加全面合理.通过本次修订进一步厘清了学科的内涵和外延,有利...     

Stress and magnetic field-dependent Young's modulus in single crystal iron-gallium alloys

The variability in Young's modulus of single crystal iron-gallium (Galfenol) alloys having 16, 17.5, 19, 24.7 and 29 at% gallium is investigated using experiments and simulations. Some of these alloys showed more than 60% change in Young's modulus along the 〈1 0 0〉 directions on varying their magnetization and stress states compared to their modulus at magnetic saturation. A function, ΔE(σ,H), is defined such that the variability of modulus is bound between 0% and 100%. The observations are related to the inherent magnetomechanical coupling in the material. An energy-based non-linear constitutive model is used to predict the variable modulus in Galfenol as a continuous function of stress and magnetic field. Model predictions showed good correlation with experimental results.     

A note on surface stress and surface tension and their interrelation via Shuttleworth’s equation and the Lippmann equation

Some aspects of the thermodynamics of solid surfaces, in particular with respect to the surface stress, f, and surface tension, γ, including the case of solid electrodes, are examined in view of their controversial discussion in part of the recent literature. By inspection of the phenomenology that requires a distinction between f and γ, and of a toy model designed to highlight the underlying fundamental science, it is shown that some of the recent publications give misleading conclusions. These include [V.A. Marichev, Surf. Sci. 600 (19) (2006) 4527; E.M. Gutman, J. Phys. Condens. Matter. 7 (48) (1995) L663; D.J. Bottomley, T. Ogino, Phys. Rev. B 63 (2001) 165412]. In spite of claims to the contrary, the validity of the equations of Shuttleworth, Lippmann, and Couchman and Davidson is not impaired by the arguments of the aforementioned articles.     

A correlation to predict heat-transfer rates of a miniature loop thermosyphon

This research is aimed at enhancing the traditional thermosyphon by preventing flooding and drying out from the opposite directions of the vapor and liquid. A miniature loop thermosyphon (MLT) consists of three sections, namely, the evaporator, the adiabatic and condenser sections. The return liquid channel is connected between the condenser and the evaporator to convey the condensed liquid. The MLT has a ratio of internal diameter of the condenser section to internal diameter of the evaporator section (Idc/Ide), which is 1.4. The MLT was made from a copper tube of 15-mm, 19-mm, and 22-mm ID. The filling ratios of the working fluid were 30%, 50%, and 80% of evaporator volume with an inclination angle of 90°. The operating temperatures were 70°C, 80°C, and 90°C with ratios of Ide/Idr of 3, 3.8, and 4.4. The research reports the effect of dimensionless parameters on heat-transfer characteristics, namely, Bo, Pr, We, Fr, Ja, Ku, ρ _υ /ρ _l, and Ide/Idr. It was found that the Bo, Pr, Ja, Ku, ρ _υ /ρ _l, and Ide/Idr have no effect on heattransfer characteristics. The We, Fr, and Ku have an effect on the heat-transfer characteristics as with increasing We, Fr, and Ku, the heat-transfer characteristics decrease. The research established another modified Kutateladze number, which can also be used to predict MLT in the vertical position.     

Three-dimensional vibration analysis of joined thick conical — Cylindrical shells of revolution with variable thickness

A three-dimensional (3-D) method of analysis is presented for determining the free vibration frequencies of joined thick conical-cylindrical shells of revolution with variable thickness. Unlike conventional shell theories, which are mathematically two-dimensional (2-D), the present method is based upon the 3-D dynamic equations of elasticity. Displacement components u_r, u_θ, and u_z in the radial, circumferential, and axial directions, respectively, are taken to be periodic in θ and in time, and algebraic polynomials in the r and z directions. Potential (strain) and kinetic energies of the joined shells are formulated, and the Ritz method is used to solve the eigenvalue problem, thus yielding upper bound values of the frequencies by minimizing the frequencies. As the degree of the polynomials is increased, frequencies converge to the exact values. Convergence to four-digit exactitude is demonstrated for the first five frequencies. Natural frequencies are presented for different boundary conditions. Comparisons are made between the frequencies from the present 3-D Ritz method and 2-D thin shell theories by previous researchers.     

New Optimal Asymmetric Quantum Codes Derived from Negacyclic Codes

The construction of quantum maximum-distance-separable (MDS) codes have been studied by many researchers for many years. Here, by using negacyclic codes, we construct two families of asymmetric quantum codes. The first family is the asymmetric quantum codes with parameters $[[q^{2}+1,q^{2}+1-2(t+k+1),(2k+2)/(2t+2)]]_{q^{2}}$ , where 0≤t≤k≤(q?1)/2, $q \equiv1(\operatorname{mod} 4)$ , and k, t are positive integers. The second one is the asymmetric quantum codes with parameters $[[(q^{2}+1)/2,(q^{2}+1)/2-2(t+k),(2k+1)/(2t+1)]]_{q^{2}}$ , where 1≤t≤k≤(q?1)/2, and k, t are positive integers. Moreover, the constructed asymmetric quantum codes are optimal and different from the codes available in the literature.     

Effect of irradiation on microstructure and hardening of Cr–Fe–Ni–Mn high-entropy alloy and its strengthened version

ABSTRACT

A single-phase fcc high-entropy alloy (HEA) of 20%Cr–40%Fe–20%Mn–20%Ni composition and its strength with yttrium and zirconium oxides version was irradiated with 1.4?MeV Ar ions at room temperature and mid-range doses from 0.1 to 10 displacements per atom (dpa). Transmission electron microscopy (TEM), scanning transmission electron microscopy with energy dispersive X-ray spectrometry (STEM/EDS) and X-ray diffraction (XRD) were used to characterise the radiation defects and microstructural changes. Nanoindentation was used to measure the ion irradiation effect on hardening. In order to understand the irradiation effects in HEAs and to demonstrate their potential advantages, a comparison was performed with hardening behaviour of 316 austenitic stainless steel irradiated under an identical condition. It was shown that hardness increases with irradiation dose for all the materials studied, but this increase is lower in high-entropy alloys than in stainless steel.     

Measurements and modelling of oxy-fuel coal combustion

Oxy-fuel combustion is one of the most promising technologies to isolate efficiently and economically CO₂ emissions in coal combustion for the ready carbon sequestration. The high proportions of both H₂O and CO₂ in the furnace have complex impacts on flame characteristics (ignition, burnout, and heat transfer), pollutant emissions (NO_x, SO_x, and particulate matter), and operational concerns (ash deposition, fouling/slagging). In contrast to the existing literature, this review focuses on fundamental studies on both diagnostics and modelling aspects of bench- or lab-scale oxy-fuel combustion and, particularly, gives attention to the correlations among combustion characteristics, pollutant formation, and operational ash concerns. First, the influences of temperature and species concentrations (e.g., O₂, H₂O) on coal ignition, volatile combustion and char burning processes, for air- and oxy-firing, are comparatively evaluated and modelled, on the basis of data from optically-accessible set-ups including flat-flame burner, drop-tube furnace, and down-fired furnace. Then, the correlations of combustion-generated particulate/NO_x emissions with changes of combustion characteristics in both air and oxy-fuel firing modes are summarized. Additionally, ash deposition propensity, as well as its relation to the formation of fine particulates (i.e. PM_0.2, PM₁ and PM₁₀), for both modes are overviewed. Finally, future research topics are discussed. Fundamental oxy-fuel combustion research may provide an ideal alternative for validating CFD simulations toward industrial applications.     

The study of microwave pressure lineshifts

The results of experimental investigations of pressure shifts and broadening of spectral lines of polar molecules performed in the submillimeter region by a microwave spectrometer RAD are reported. About 30 measurements were made of self-shift and foreign gas shift parameters of the lines of NH₃, PH₃, AsH₃, and H₂O molecules including lineshifts in excited vibrational states, lineshifts of transitions connected by common levels, lines with various values of J and K quantum numbers, and the “forbidden” |ΔK| = 3 lines. On the basis of the data obtained in this work and data available in the literature, new experimental dependences of lineshifts on molecular parameters are found. The results are well described by a simple “Stark effect” model of lineshifts. Some new directions of investigations are outlined.     

Impact and structure of literature on nanoparticle generation by laser ablation in liquids

The number of publications on laser ablation and nanoparticle generation in liquids increased by the factor of 15 in the last decade, with comparable high impact of the most cited articles in this field. A nearly unlimited variety of nanoparticle material, liquid matrix, and conjugative agent can be combined to a huge variety of colloids within a few minutes of laser processing. However, this diversification makes it hard to identify main research directions without a comprehensive literature overview. This investigation evaluates the impact and structure of the literature in this field tagging most prolific subjects and articles. Using an optimized search algorithm, the data sets derived from Science Citation Index (1998–2008) allow for statements on publication subject clusters, impact of articles and journals, as well as mapping global spots of activities.     

Basic thermophysical parameters of langasite (La3Ga5SiO14), langatate (La3Ta0.5Ga5.5O14), and catangasite (Ca3TaGa3Si2O14) single crystals in a temperature range of 25 to 1000°C

The thermophysical parameters (thermal diffusivity ??, heat conductivity ??, thermal expansion, and specific heat c _p coefficients) of single crystals from the langasite family are investigated in the basic crystallographic directions of X, Y, and Z in temperature range of 300 to 1300 K. The temperature dependences of the parameters are determined. It is found that their anisotropy decreases with temperature.     

Application of the Stoner-Wohlfarth model with interaction for the determination of the saturation magnetisation, anisotropy field, and mean field interaction in bulk amorphous ferromagnets

Magnetic hysteresis curves of bulk amorphous ferromagnet alloys of composition Nd₆₀Fe₃₀Al₁₀, Nd₆₀Fe₂₀Co₁₀Al₁₀ and Pr₅₈Fe₂₄Al₁₈ have been measured in applied magnetic fields up to 9 T at temperatures in the range 10-350 K. The behaviour of the demagnetisation curve in the first quadrant is interpreted using a mean field interaction model as proposed by Callen et al. [Phys. Rev. B 16 (1977) 263], which extends the Stoner-Wohlfarth model [Philos. Trans. Roy. Soc. A 240 (1948) 599] for a random distribution of non-interacting uniaxial grains. Application of the mean field interaction model enables the determination of the saturation magnetisation M_s, anisotropy field H_a, and interaction parameter d, and from these other magnetic parameters, such as the anisotropy constant, K, are deduced. For the three alloys, the temperature dependent behaviour of M_s, H_a, d and K over the range 20-350 K are found to be qualitatively similar, though there are quantitative differences. In all cases M_s increases with decreasing temperature, both H_a and K increase with decreasing temperature, reaching a peak in the range 75-120 K, and then decreasing, and d decreases approximately linearly as the temperature decreases. The physical mechanisms responsible for coercivity in these materials are discussed in the context of random anisotropy and a strong pinning model of domain walls.     

Magnetic structures and magnetocrystalline anisotropy in bulk and thin film Fe3Pt

Magnetic structures and magnetocrystalline anisotropy (MCA) of tetragonal phase Fe₃Pt with an L1₂ atomic ordering in bulk and thin film are investigated by means of the first-principles full-potential linearized augmented plane-wave method. The results obtained predict that the tetragonal phase, in which the tetragonal distortion with (c/a) = 0.95 makes an asymmetry of magnetic properties along the c-axis (out-of-plane) and a-axis (in-plane), has an out-of-plane MCA. In addition, from the thin film calculations, the presence of surface is found to strongly enhance the out-of-plane MCA.     

Bibliometric Analysis on Supercritical CO2 Power Cycles for Concentrating Solar Power Applications

In recent years, supercritical CO₂ power cycles have received a large amount of interest due to their exceptional theoretical conversion efficiency above 50%, which is leading a revolution in power cycle research. Furthermore, this high efficiency can be achieved at a moderate temperature level, thus suiting concentrating solar power (CSP) applications, which are seen as a core business within supercritical technologies. In this context, numerous studies have been published, creating the need for a thorough analysis to identify research areas of interest and the main researchers in the field. In this work, a bibliometric analysis of supercritical CO₂ for CSP applications was undertaken considering all indexed publications within the Web of Science between 1990 and 2020. The main researchers and areas of interest were identified through network mapping and text mining techniques, thus providing the reader with an unbiased overview of sCO₂ research activities. The results of the review were compared with the most recent research projects and programs on sCO₂ for CSP applications. It was found that popular research areas in this topic are related to optimization and thermodynamics analysis, which reflects the significance of power cycle configuration and working conditions. Growing interest in medium temperature applications and the design of sCO₂ heat exchangers was also identified through density visualization maps and confirmed by a review of research projects.     

Generalized susceptibilities and phonon anomalies in Pd and Pt metals

The generalized susceptibility, χ(q), in Pd and Pt for q along the [100], [110], [111], and [120] directions was determined from their APW and RAPW energy band structures, respectively, using the analytic tetrahedron linear energy scheme of Rath and Freeman. The band structures were previously found to yield Fermi surface radii, temperature dependencies of the static magnetic susceptibility, χ(T), resistivity, and a spin lattice relaxation, T₁T, in very good agreement with experiment. In the χ(q) calculations, we used 2048 tetrahedra in 1/48th irreducible BZ and the energy eigenvalues for bands 4, 5, and 6 which cross the Fermi energy as fitted to a Fourier series representation. The intraband parts of χ(q) at q = 0 for both metals are found to agree with the density of states at the Fermi energy to without 0.5%. Our results show that the dominant contribution to χ_intra arises from the dominant band 5 whose “jungle-gym” FS has strong nesting features; the main peak for Pd occurs at the same q value (= 0.65π/a) for q along the [0q0], [q, q, 0], and [q, q, q] directions. The locus of this main peak is a square in the (0, 0, 1) plane. The maximum of χ_intra for q along the [110] and [111] directions are 23% and 13%, respectively, higher than the value of χ(q) at q = 0. For q along the [010] and [120] directions, the peak is, however, lower than the value of χ_intra at q = 0. Hence, while phonon anomalies are predicted for the [110] and [111] directions, no anomaly is predicted for either the [100] or [120] direction. The predicted q value for the [110] anomaly, $\text{q}\text{= 0.65π/a}$ is close to the experimental value of ～0.7 π/a. Although there may be a hint of an anomaly at 0.56 [111] in the measurements, a more detailed investigation of this region is called for. For platinum, χ_intra for q along the [010], [110] and [111] directions has main peaks which occur at q = 0.68 π/a, 0.75 π/a, and 0.85 π/a, respectively. Here too, this main peak comes from the nesting of the jungle-gym Fermi surface which is not, however, as flat as that of palladium. Anomalies are predicted (although weaker in Pt than in Pd) along [110] and [111] but not along [100] and [120]. The [110] anomaly is close to the measured q value (～0.7–0.8 π/a). Also in agreement with experiment, we predict a weaker [110] anomaly for Pt than for Pd. In both Pd and Pt, weaker anomalies are predicted for the [111] direction than for the [110] direction.