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Whole abdomen radiotherapy (WART) is used to treat pediatric malignancies with a high risk of peritoneal spread. WART with X-Ray (XRT) based intensity-modulated radiation therapy (IMRT) has been reported to reduce acute toxicities compared to conventional radiotherapy (CRT). Proton beam therapy (PBRT) may further reduce toxicities. We compare treatment logistics, dosimetry, and outcomes for WART with PBRT and XRT. A retrospective chart of pediatric patients receiving WART at a single center from 2014 to 2023 was performed. Dosimetric parameters, treatment delays, replanning needs and outcomes were compared between patients receiving XRT and PBRT. T-tests were used for statistical analysis where appropriate. 13 patients (7 male) with Wilms tumor (WT) (n = 11) or embryonal rhabdomyosarcoma (ERMS) (n = 2) were included. Median age at RT was 5.8 years (range 1.4-11.0). Nine WT patients received 10-17 Gy in 7 fractions and two received 18-20 Gy in 12-13 fractions. The ERMS patients received 30-36 Gy in 20 fractions. Median time from simulation to RT start was 5.5 days (range 1-8) for XRT and 8.4 days (range 5-13) for PBRT (p = 0.09). No significant differences were observed for mean dose to kidneys, femoral growth plates, vertebrae, bladder, liver, heart or V8.5 Gy and V15Gy for the liver between XRT or PBRT. The 6Gy volume in the kidneys approached significance, PBRT plans indicated significant bilateral femoral head sparing (p = 0.027). Median RT duration was 9 days (range 8-30). Of the seven PBRT patients, two required mid-treatment replanning, and two switched mid-PBRT to IMRT due to significant daily bowel content variability. Two PBRT patients had unanticipated interruptions during RT: one for replanning and a 2nd for management of increased ascites. All 6 XRT (5 IMRT, 1 3D XRT) patients completed their treatment as planned with no interruptions. Median follow-up duration post-treatment was 29.4 months (range 2.7-101.2). At last follow-up, 1 patient died of disease, 1 was undergoing treatment, and 11 had no evidence of disease recurrence or progression. IMRT and PBRT WART achieved at least comparable abdominal organ-at-risk sparing in pediatric patients. PBRT may offer some dosimetric advantages, such as better sparing of femoral heads. PBRT requires more planning time, verification scans, and replans. We note that careful evaluation of treatment set up and bowel content surveillance is necessary to insure appropriate planning and delivery of PBRT for WART. Individualized modality selection balancing efficacy, availability, and efficiency is warranted. Further study of long-term outcomes and strategies to reduce PBRT delivery complexity is needed. [ABSTRACT FROM AUTHOR]

Multi-cancer early detection (MCED) tests offer population-based screening for cancer using minimally invasive blood-based sampling and are now commercially available on a self-pay basis. Patients may be identified as at risk for head and neck cancer (HNC) based on a positive signal and predicted site of origin. Detailed information about subsite of origin is not available. There are currently no consensus guidelines available for HNC providers to direct work up or surveillance for these patients. We report an early case series which highlights considerations when evaluating patients referred for a positive commercially obtained MCED test. Retrospective chart review of patients referred to Otolaryngology-Head and Neck Surgery (Oto-HNS) with an at risk MCED result. Patients who were enrolled in unpublished prospective clinical trials were excluded. Three patients were identified as high risk for HNC and one patient had a positive lymphoma MCED test (mean age: 70.8 years, range: 50-87; 3 male). All were asymptomatic. Patient 1 was at risk for HNC on MCED and had an abnormal oropharyngeal exam, H&N CT, PET/CT, and was diagnosed with pT2N1M0 p16(+) oropharygeal squamous cell carcinoma (HPV(+)OPSCC). Patient 2 was at risk for HNC and had a neck mass on exam, abnormal H&N CT, abnormal PET/CT, tested positive for circulating tumor HPV DNA (ctHPVDNA), and was diagnosed with pT2N1M0 HPV(+)OPSCC. Patient 3 was at risk for HNC and lung on MCED, had a normal H&N exam, an indeterminate 8-9 mm deep lobe parotid mass on H&N CT, H&N MRI, and H&N US, and a thigh mass on PET/CT, and was diagnosed with high grade undifferentiated pleomorphic sarcoma of the thigh. Due to the small size of the parotid mass, location, patient age and pressing comorbidities, radiographic surveillance with MRI and exam in 6 months was recommended. Patient 4 was referred to Oto-HNS for a positive lymphoma MCED test for H&N exam, and had no abnormal findings on exam or PET/CT. This patient is undergoing surveillance with MRI and exam in 6 months. The average time from MCED test result to clinical diagnosis was 42 days (range: 26-56 days). In this case series, 67% (2/3) of patients referred with a positive MCED result suggesting HNC were diagnosed with HPV(+)OPSCC. We recommend that positive H&N MCED results be. Currently, work up should include a thorough H&N examination including flexible laryngoscopy and focused CT imaging. The performance of tissue of origin classifiers for squamous malignancies may be less accurate, supporting the use of a PET/CT scan in this setting. ctHPVDNA may be a useful adjunct for indeterminate imaging and physical exam findings. For a patient with no cancer identified, development of clear guidelines are warranted. [ABSTRACT FROM AUTHOR]

• Nanolayer thickness is calculated with varying silica wall thicknesses. • A modified model is proposed to predict the melting enthalpy of composite PCM. • Heat flux is decomposed to reveal the contributions of nanolayer. Thermophysical properties of composite phase change materials (PCMs) are influenced by the interfacial nanolayer. Molecular dynamics (MD) method is used to study the effect of interfacial nanolayer on thermophysical properties of silica-paraffin composite PCM. The simulation results show that the melting enthalpy is reduced from 197.9 J·g−1 to 29.1 J·g−1, and the thermal conductivity is enhanced from 0.142 W·m−1·K−1 to 0.268 W·m−1·K−1, when the silica thickness is increased from 0 to 15.0 Å. The interfacial nanolayer is observed in composite PCM, and its thickness increases with the increase of silica wall thickness. In the composite PCM with 7.0 Å silica wall, a loss of 62.9% in the melting enthalpy is observed, with 32.6% attributed to the silica mass and 30.3% attributed to the nanolayer. Based on that, a modified model is proposed to predict the melting enthalpy of composite PCMs by considering the effects of both silica mass fraction and nanolayer. To reveal the thermal conductivity enhancement mechanism, the total heat flux is decomposed into three terms (namely, kinetic energy term, potential energy term and interaction energy term). It is found that the interaction energy term has the largest contribution to the total heat flux. The presence of nanolayer strengths the interactions, leading to the thermal conductivity enhancement. [ABSTRACT FROM AUTHOR]

• We have proposed a data-driven machine learning workflow for designing multilayer hyperbolic metamaterials composed of α-MoO 3 , achieving high modulation contrast in near-field thermal radiation. • By combining the multilayer perceptron and bayesian optimization techniques, we optimize the rotation angle, layer thickness, and gap distance of the multilayer metamaterials, resulting in a 97 % improvement in thermal modulation contrast compared to previous single layer structures. • The large thermal modulation contrast is attributed to the controlled alignment and misalignment of hyperbolic plasmon polaritons and hyperbolic surface phonon polaritons in each layer, achieved by manipulating the rotation angles. The thermal modulator based on the near-field radiative heat transfer has wide applications in thermoelectric diodes, thermoelectric transistors, and thermal storage. However, the design of optimal near-field thermal radiation structure is a complex and challenging problem due to the tremendous number of degrees of freedom. In this work, we have proposed a data-driven machine learning workflow to efficiently design multilayer hyperbolic metamaterials composed of α-MoO 3 for near-field thermal radiative modulator with high modulation contrast. By combining the multilayer perceptron and Bayesian optimization, the rotation angle, layer thickness and gap distance of the multilayer metamaterials are optimized to achieve a maximum thermal modulation contrast ratio of 6.29. This represents a 97 % improvement compared to previous single layer structure. The large thermal modulation contrast is mainly attributed to the alignment and misalignment of hyperbolic plasmon polaritons and hyperbolic surface phonon polaritons of each layer controlled by the rotation. The results provide a promising way for accelerating the designing and manipulating of near-field radiative heat transfer by anisotropic hyperbolic materials through the data-driven style. [Display omitted] [ABSTRACT FROM AUTHOR]

Radiation therapy (RT) can provide effective palliation and prevent symptomatic local progression of multiple myeloma (MM). However, RT is sometimes avoided due to concerns for secondary impact to bone marrow, potentially decreasing blood cell counts and precluding ability to receive future systemic therapies. We reviewed a series of MM patients who received palliative RT to assess changes in blood counts from pre-RT to post-RT, hypothesizing that blood counts would not significantly decline after treatment with modern RT volumes and techniques. We utilized a prospectively maintained departmental database and included patients who received palliative RT for MM from 2015 to 2020. Lab values immediately pre-RT (within one month of RT start date) and post-RT (within three months of RT completion) including hemoglobin, lymphocytes, neutrophils, and platelets were collected. Statistical differences from pre-RT to post-RT were assessed using t-tests. ANOVA was used to compare change in blood counts between common dose fractionation regimens (30 Gy in 10 Fractions, 20 Gy in 5, and 8 Gy in 1). A total of 334 MM patients receiving 424 courses of RT were included in this analysis. The median age at start of first treatment was 67 (IQR: 60-76) years. One-hundred ninety-five (58%) were male. Median RT dose was 20 (IQR: 8-24.5) Gy delivered over a median 5 (IQR: 1-5) fractions. Between pre-RT and post-RT, there was no significant change in hemoglobin (+0.1 g/dL (IQR: -0.8, +0.5), p =.076), lymphocyte counts (-0.3*10^9 cells/L (IQR: -0.6, 0), p =.435), or neutrophil counts (-0.1*10^9 cells/L (IQR: -1.1, +0.9), p =.310). In contrast, platelet counts significantly decreased from pre-RT (median 165*10^9 cells/L, IQR: 112-210) to post-RT (median 146, IQR: 93-194) by a median of 17.5 *10^9 cells/L (IQR: -52.5, +14.0, p<0.0001). There were no differences in changes in hemoglobin, neutrophils, or platelets between the common dose fractionations. However, there was a significantly greater drop in lymphocytes after 30 Gy in 10 fractions (p =.039, mean lymphocyte count change (in 10^9 cells/L) for 30 Gy in 10: -0.87, 20 Gy in 5: -0.47, and 8 Gy in 1: -0.27). In this large dataset of patients receiving modern palliative RT for MM, hemoglobin, lymphocytes, and neutrophils did not significantly decline from pre-RT to post-RT. In contrast, there was a statistically significant drop in platelet count by a median 17.5*10^9 cells/L from pre-RT to post-RT, which may or may not be clinically significant depending on clinical context. Patients receiving 30 Gy in 10 fractions had greater drops in lymphocytes than those receiving lower doses. Further analyses will be performed to determine clinical, dosimetric, and volumetric predictors of decline in blood counts after radiation. [ABSTRACT FROM AUTHOR]

Thermochemical heat storage is a promising technology for the efficient utilization of renewable energy. Among available thermochemical systems, the CaO/Ca(OH) 2 system is the most popular because of availability and cost. However, poor powder properties and low heat storage rates hinder the successful implementation of this system. This study presented a novel synthetic method of granular composites based on carboxymethyl cellulose sodium (CMC) and vermiculite in order to mitigate the drawbacks of natural materials and stabilize the size of materials for use in moving bed reactors. TGA and DSC experiments and some essential characterizations were done in order to evaluate the improvements on the basis of three objectives: the heat storage rate, heat storage density, and mechanical properties, compared with natural materials. Results showed that the granular composite still had great structural integrity after several dehydration/hydration cycles, whereas compacted natural materials had fragmented. Additionally, composite had a higher heat storage rate than natural materials. The gravimetric storage density of granular composite was slightly reduced while the volumetric storage density was enhanced up to approximately 124% as compared to the powdery Ca(OH) 2 material. It was concluded that present synthetic method is a promising route for the development of Ca-based composite materials. • A novel synthetic method of granular composites based on CMC and vermiculite is developed. • Granular composites still have great structural integrity after several cycles. • The heat storage rate of composite is improved compared with natural materials. • The volumetric storage density of composite materials is slightly enhanced. [ABSTRACT FROM AUTHOR]

• SiO 2 addition in CaCO 3 stabilizes the cyclic stability and lowers the decarbonation temperature. • CaCO 3 /CaO system works efficiently for temperatures from 750 to 925 °C. • CaCO 3 /CaO system doped with SiO 2 works efficiently for temperatures from 700 to 800 °C. CaCO 3 is a promising material for thermochemical energy storage (TCES) systems. It can store and release heat upon reversible decarbonation to CaO, which emits heat through carbonation. Decarbonation temperature of CaCO 3 directly affects the properties of CaO, which influences heat supply in result. The current research studies CaCO 3 /CaO system, specifically analyzing the conversion of CaO into CaCO 3 (carbonation) for various CaO samples prepared at decarbonation temperatures between 600 and 975 °C. A relation is developed using regression analysis to verify the linearity between reactivity of CaO samples and decarbonation temperature at which it was prepared. The carbonation of all CaO samples at various partial pressures of CO 2 and temperatures is also analyzed. The whole process is performed for pure and SiO 2 doped systems (molar ratio 1:1). The efficient performance of CaCO 3 /CaO system is noted for decarbonation temperatures above 750 °C or below 925 °C for pure material. While for doped material, the decarbonation temperature for efficient performance lies between 700 °C and 800 °C. Both systems performed with higher efficiency when CO 2 pressure was kept constant and the carbonation temperature was increased. [ABSTRACT FROM AUTHOR]

• A principle to achieve near-perfect full-spectrum photothermal usage is developed. • The volume concentration of nanoparticles and nanofluids' thickness can be flexibly chosen. • The 99% photothermal efficiency is obtained using SiO 2 @Ni (TiN) nanofluids. • High photothermal efficiency can be ensured at small volume concentration and thickness. Although achieving efficient solar-thermal conversion with nanofluids (NFs) plays an important role in developing photothermal technologies, full-spectrum energy usage is still challenging currently. In this work, dimensionless methods of designing NFs are proposed in complex permittivity (ε) space, to make the most of solar energy. Firstly, an effective regime Ω ′ for each size parameter x is determined, in which an ideal photothermal efficiency can be guaranteed if only the NPs' permittivity falls into this area. Besides, on the other hand, by introducing a dimensionless parameter Q i , our methods also allow to actively chose properties of NFs with a desirable solar-to-thermal efficiency, including volume concentration of NPs ( f v ) and thickness of NFs (L). Based on the proposed principles, results show that SiO 2 @Ni and SiO 2 @TiN NFs perform better with efficiency 15–30% improved than other widely used materials, such as SiO 2 @Ag(Au, Al) counterparts. Further, genetic algorithms are employed to verify the above results. Consistently, it suggests that near-perfect full-spectrum photothermal efficiency of SiO 2 @Ni or SiO 2 @TiN NFs can be obtained, reaching to 99% under certain conditions. In addition, regarding these two superior NFs, appreciable performance can also be protected with considerably small values of f v and L , which helps to reduce costs and is attractive in practice. The proposed principles offer a powerful tool to actively design optimized NP-related NFs for achieving perfect photothermal conversion, which will also potentially stimulate the development of other advanced photothermal technologies. [ABSTRACT FROM AUTHOR]

Highlights • A 30–50 K deterioration of thermal insulation performance of functionally graded thermal barrier coatings (FGTBCs) compared to traditional TBCs is reported. • Thermophysical properties of Functional Graded Materials(FGMs) are experimentally determined. • A comprehensive heat transfer model was built to predict the stationary temperature distribution and heat flux inside FGTBCs. Conduction heat flux and thermal radiation flux were analyzed separately. Abstract To further study the heat transfer process inside the functionally graded thermal barrier coatings (FGTBCs) beyond the companion part of the present paper concerning their radiative properties, this paper takes both conductive and radiative heat transfer into account and establishes a comprehensive heat transfer model considering both conductive and radiative heat transfer to estimate the thermal insulation performance of FGTBCs. Thermal conductivities of more than thirty yttria-stabilized zirconia (YSZ)/NiCoCrAlY FGTBC samples were determined based on their thermal diffusivities determined by the laser flash analysis. To predict the overall thermal insulation performance of 8YSZ/NiCoCrAlY FGTBCs, a comprehensive heat transfer model based on the two-flux method and multi-band model was built to solve the stationary temperature distribution and heat flux inside thermal barrier coatings (TBCs) and FGTBCs. Results indicate that FGTBCs show worse thermal insulation performance compared to conventional YSZ TBCs; we also investigated the influence of the number of layers. The temperature of engine blade is increased by 30 – 50 K if coated with an FGTBC instead of a conventional TBC. Conduction heat flux is significantly greater than radiative flux for both TBCs and FGTBCs. This paper gives a detailed analysis by simultaneously considering the heat conduction and thermal radiation in FGTBCs, which is helpful for achieving better thermal design of YSZ/NiCoCrAlY FGTBCs. Along with the Part I, this two-part article presents a deep and thorough study on the thermal insulation performance of YSZ/NiCoCrAlY FGTBCs. [ABSTRACT FROM AUTHOR]

Highlights • Decreased reflectance of YSZ/NiCoCrAlY Functionally Graded Thermal Barrier Coatings (FGTBCs) compared to that of conventional YSZ TBCs. • Determination of spectral absorption coefficients and spectral scattering coefficient of YSZ TBCs and YSZ/NiCoCrAlY mixture coatings. • The role of ceramic top coating in radiative properties of ceramic-metal FGTBCs. Abstract Functionally graded thermal barrier coatings (FGTBCs) are functional composites with multilayered structures whose mechanical properties are better than those of conventional ceramic thermal barrier coatings (TBCs). Although many theoretical and experimental studies concerning both the mechanical properties and heat transfer including heat conduction and thermal radiation of TBCs have been conducted, little attention was paid to heat transfer process, especially the coupled conduction-radiation heat transfer, inside FGTBCs. This two-part paper systematically studied the heat transfer inside YSZ/NiCoCrAlY FGTBCs. In Part I, we investigated their radiative properties through experimental measurements. In Part II, we presented a study on the thermal conductivity of FGTBCs and established a coupled heat transfer model. In this paper, more than thirty yttria-stabilized zirconia (YSZ)/NiCoCrAlY duplex TBC and multilayered FGTBC samples with different multilayer structures, porosities and thicknesses were fabricated via air plasma spraying. The transmittance and reflectance spectra within the 0.3 – 15 μ m wavelength range were experimentally obtained by UV–visible spectrometry and Fourier transform infrared spectroscopy. A scanning electron microscope analysis was carried out to characterize the microstructures of FGTBCs. Additionally, we studied each layer of the FGTBCs individually; the four-flux method was employed to obtain the radiative properties based on our experimental measurements. Functionally graded materials (FGM) show larger absorption coefficients and smaller scattering coefficients compared to pure YSZ. The FGTBCs show lower reflectance than YSZ TBCs. We also study the influence of the number of layers on reflectance. The results indicate that FGTBCs have worse thermal insulation ability against radiative flux tconventional ceramic TBCs of the same thickness. This paper provides practical guidance to improve the design of YSZ/NiCoCrAlY FGTBCs and other FGM coatings to reach a balance between good thermal insulation and mechanical strength. [ABSTRACT FROM AUTHOR]

Abstract Cascaded Thermal Storage (CTS) technique is an efficient solution for storing solar thermal energy of high quality. In this paper, heat transfer rate and thermodynamic irreversibility are combined for optimizing cascaded PCM thermal storage system based on entransy and entropy. Optimal solutions for temperature of CTS unit are obtained based on entransy and entropy, which cannot only present a benchmark for similar research, but also be used for guiding phase change material (PCM) selection of multi-PCM thermal storage device. Limitations for entransy and entropy optimizations are put forward, and comprehensively analyzed. A parametric study is performed for the optimal thermal performance. The optimal PCM temperature based on entropy is geometric while that based on entransy is linearly distributed. By increasing stage number or heat transfer parameter, optimal performances for optimizations of entransy and entropy are promoted. Results show that thermal efficiency in entransy optimization is greater than that in entropy optimization while the exergy efficiency in entropy optimization is superior to that of entransy optimization. Stage number should be adjusted by balancing earnings and costs for cascaded design of thermal storage system. Heat transfer enhancement is essential for performance promotion of cascaded system and selection of optimization principles. Graphical abstract Image Highlights • CTS system is optimized based on entransy and entropy with optimization process. • Effects of key factors on PCM temperature and thermal performance are examined. • Optimal temperature with entropy is geometric and that with entransy is linear. • The critical stage number is presented for different optimization cases. • Entransy and entropy can be used for optimizing CTS system of different purposes. [ABSTRACT FROM AUTHOR]

Highlights • we propose a theoretical investigation of the near-field thermal radiative transfer (NFTRT) between two assembled spherical systems composed of core-shell nanoparticles in multibody mutual interaction. • The core-shell nanoparticles inherit both characteristics of SiC and n-type Ge: quasi-monochromatic and broad-band, and allow for a large freedom of tunability. • Multibody mutual interaction has a detrimental effect on the NFTRT between two assembled spherical systems due to more energy scattered to the environment. • The enhancement of NFTRTs between a small proportion of nanoparticle dimers inside the systems is observed, which can be attributed to the coherence enhancement of fluctuating thermal fields. • By analyzing the trace of a dyadic Greens functions product, the locations of the inherent resonance of nanoparticles and the coherent enhancement due to multibody mutual interaction need to be consistent if we hope strong exaltation effects of NFTRT. Abstract Thermal radiative transfer can be enhanced significantly when the distance of radiation sources is smaller than the characteristic wavelength of thermal radiation. However, the problem of the near-field thermal radiative transfer (NFTRT) between core-shell nanoparticles has rarely been studied. Moreover, most previous studies investigate the NFTRT between two or three nanoparticles, while few works have been done on real many-body systems where multibody mutual interaction plays a pivotal role. In this study, we choose silicon carbide (SiC) and n -type germanium (Ge) as two constituent materials of the core-shell nanoparticle, and describe a complete theoretical investigation of the NFTRT in many body systems composed of core-shell nanoparticles. The results demonstrate that the core-shell nanoparticles inherit both characteristics of SiC and n -type Ge: quasimonochromaticity and broad-band. What's more, the spectral features can be tuned by core-shell radius and material composition. Further studies show that multibody mutual interaction has a detrimental effect on the NFTRT between two assembled spherical systems. Still, the enhancement of NFTRTs between a small proportion of nanoparticle dimers inside the systems is observed, which can be attributed to the coherence enhancement of fluctuating thermal fields. And by analyzing the trace of a dyadic Greens functions product, the locations of inherent resonance of nanoparticles and the coherent enhancement due to multibody mutual interaction need to be consistent if we hope strong exaltation effects of NFTRT. [ABSTRACT FROM AUTHOR]

• Topological phonon polaritons (TPhPs) are shown to be sustained by a family of onedimensional quasiperiodic silicon carbide nanoparticle chains. • TPhPs can significantly improve radiative heat transfer, evidenced by longitudinal and transverse heat spectra and eigenmode decomposition. • The complicated interplay among topological order, long-range quasiperiodic order and nearfield electromagnetic interactions can lead to substantial modulations of radiative heat transfer. Topological phonon polaritons (TPhPs) are localized boundary modes arising from the combination of topological photonics and phonon polaritons in micro/nanostructures made of polar dielectrics, which are capable of mediating long-range radiative heat transfer and infrared sensing in a robust manner. This work shows TPhPs can be sustained in a family of one-dimensional quasiperiodic silicon carbide nanoparticle (NP) chains, and can significantly improve radiative heat transfer for these arrays. This family of 1D quasiperiodic lattices is a continuous interpolation between the two paradigmatic limits, viz., the off-diagonal Aubry-André-Harper (AAH) chain and the Fibonacci chain. For different interpolation parameters τ , the band structures are calculated with respect to the modulation phase ϕ as the wavenumber in a synthetic dimension, where a series of gaps and midgap edge states can be observed. These edge states are shown to be topologically protected by applying the gap-labeling theorem and the principle of bulk-boundary correspondence. By means of many-body radiative heat transfer theory for a group of electric dipoles, it is shown quasiperiodicity and topological property can have an important impact on radiative heat transfer. These results can give useful insights on the interplay among topological order, long-range quasiperiodic order, near-field electromagnetic interactions and radiative heat transfer. [ABSTRACT FROM AUTHOR]

By meticulously considering the hydrogen evolution reaction (HER) on the nickel foam cathode with both uniform and gradient pore diameters, a multi-field three-dimensional model is developed utilizing the open-source computational fluid dynamics (CFD) program OpenFOAM. Leveraging this simulation, we investigate the impacts of different gradient orientations and thickness configurations on critical processes including mass transfer and ion transport. The findings indicate that at a thickness ratio of 1:1 in the positive gradient arrangement, the pressure drop and hydrogen volume fraction are reduced by 10.42% and 18.66% compared to the negative gradient, respectively. However, the negative gradient arrangement with a thickness ratio exceeding 4:1 exhibits superior performance with specific external flow. This work reveals the critical roles of gradient electrodes on HER processes and provides important design principles of the electrode microstructure to promote further developments of alkaline water splitting systems to meet the requirements of their practical applications. [Display omitted] • A multi-field simulation model for hydrogen evolution reaction is constructed. • Electrodes better in gas exclusion and ion transport have the lower overpotential. • Electrodes with gradient porosity schemes foster mass and ion transport. [ABSTRACT FROM AUTHOR]

In the last a few decades, the approximate nature of radiative transfer equation (RTE) leads to a bunch of considerations on the effect of dependent scattering in random media, especially in particulate media composed of discrete scatterers. This effect usually indicates those deviations of RTE from experimental and exact numerical results due to electromagnetic wave interference. Here we theoretically and numerically demonstrate the effect of dependent scattering on absorption in disordered media consisting of highly scattering scatterers. By making comparisons between the independent scattering approximation-radiative transfer equation (ISA-RTE) approach and the full-wave coupled dipole method (CDM), we find that deviations between the two approaches increase as the scatterer density increases. The discrepancy also grows with the optical thickness of the whole random media. To quantitatively take dependent scattering effect into account, we develop a theoretical model of the dependent-scattering corrected radiative properties, based on the path-integral diagrammatic technique and the quasi-crystalline approximation (QCA) in the multiple scattering theory. The model results in a more reasonable agreement with numerical simulations. The present work is of practical importance in correctly modeling light absorptance in random media and interpreting the experimental observations in various applications for random media, such as solar energy concentration, micro/nanofluids, structural coloration, etc. It also has profound implications for the coherent scattering physics in random media with absorption. [ABSTRACT FROM AUTHOR]

The dependent scattering mechanism is known to have a significant impact on the radiative properties of random media containing discrete scatterers. Here we theoretically demonstrate the role of dependent scattering on the radiative properties of disordered media composed of nonabsorbing, dipolar particles. Based on our theoretical formulas for the radiative properties for such media, we investigate the dependent scattering effects, including the effect of modification of the electric and magnetic dipole excitations and the far-field interference effect, both induced and influenced by the structural correlations. We study in detail how the structural correlations play a role in the dependent scattering mechanism by using two types of particle system, i.e., the hard-sphere system and the sticky-hard-sphere system. We show that the inverse stickiness parameter, which controls the interparticle adhesive force and thus the particle correlations, can tune the radiative properties significantly. Particularly, increasing the surface stickiness can result in a higher scattering coefficient and a larger asymmetry factor. The results also imply that in the present system, the far-field interference effect plays a dominant role in the radiative properties while the effect of modification of the electric and magnetic dipole excitations is subtler. Our study is promising in understanding and manipulating the radiative properties of dipolar random media. [ABSTRACT FROM AUTHOR]

We propose a route to obtain broadband absorption in the mid-infrared region by coupling plasmon and phonon polaritons in compact hBN/metal metasurface. Here we show, with the assistance of the dispersion relation contours, that hybrid phonon-plasmon polaritons modes can exist in the hBN/metal heterostructures. By exciting these modes, i.e., hyperbolic phonon-plasmon polaritons in the Reststrahlen band and surface phonon-plasmon polaritons out of the Reststrahlen band of hBN, broadband near-perfect absorption can be achieved when carving the hBN/metal mutilayer into sawtooth gratings. The thickness of the gratings is about λ 0 / 13 , which is an ultra-thin metasurface compared with previous works. The electric field and power dissipation density distributions are plotted to elucidate the mechanisms of the near-perfect absorption in different regimes. Furthermore, we present a detail analysis about the influence of changing the shape of gratings on the absorption performance and quantitatively evaluate the role hBN played in the absorber. The proposed route of designing broadband absorbers will benefit many practical applications, especially in the mid-infrared range. [ABSTRACT FROM AUTHOR]

This paper investigates heat transfer performance and bubble behavior in gradient metal foam in saturated pure deionized water and n -heptanol solutions under pool boiling conditions. The gradient metal foam consists of a 40 PPI nickel foam layer with 4 mm thickness and a 10 PPI copper foam layer with 4 mm thickness; the foam porosity is 0.98. The experimental results show that n -heptanol increases the wettability of the copper surface and adversely affects the boiling heat transfer. At low heat flux, small departure bubbles attach onto the metal skeleton and then decrease in size. As heat flux increases, two common phenomena occur in the gradient foam: bubbles escape from the metal skeletons without cracking and bubbles separate into two smaller bubbles. When heat flux increases to 1 × 10 5 W m −2 , two neighboring bubbles move upwards and are then sucked into the metal foam due to coalescence. [ABSTRACT FROM AUTHOR]

Thermal barrier coatings are common porous materials coated on the surface of devices operating under high temperatures and designed for heat insulation. This study presents a comprehensive investigation on the microstructural effect on radiative scattering coefficient and asymmetry factor of anisotropic thermal barrier coatings. Based on the quartet structure generation set algorithm, the finite-difference-time-domain method is applied to calculate angular scattering intensity distribution of complicated random microstructure, which takes wave nature into account. Combining Monte Carlo method with Particle Swarm Optimization, asymmetry factor, scattering coefficient and absorption coefficient are retrieved simultaneously. The retrieved radiative properties are identified with the angular scattering intensity distribution under different pore shapes, which takes dependent scattering and anisotropic pore shape into account implicitly. It has been found that microstructure significantly affects the radiative properties in thermal barrier coatings. Compared with spherical shape, irregular anisotropic pore shape reduces the forward scattering peak. The method used in this paper can also be applied to other porous media, which designs a frame work for further quantitative study on porous media. [ABSTRACT FROM AUTHOR]

The coflow air effect on the ignition process of a methane jet diffusion flame has been investigated using high speed colour/schlieren imaging and image processing techniques experimentally. The methane flow rate is kept at constant ( Re = 55.4), while the coflow air flow rate changes ( Re from 171 to 5985), creating a wide range of the air/fuel velocity ratios varying from 0.36 to 12.5. Special digital image processing techniques are applied to visualise the weak blue flame and weak yellow flame, which is often difficult to view in the presence of the bright orange diffusion flame, during ignition process. The processed images have shown clearly that a sooty diffusion flame is initially formed inside a blue flame pocket at low air velocities. When the coflow air flow rate exceeds 75 l/min, only blue flame can be observed. The equivalence ratio of blue flame has been evaluated based on colour characteristics, which is close to 1 during the ignition process for all the cases. Moreover, the fuel flow, flame and hot gas interactions with the cold air flow are investigated by visualising the schlieren images. It is found that a hot gas bulge is formed due to the excessive fuel exiting before ignition and a hot laminar central jet is formed with the help of coflow effect. The hot gas bulge tip and bottom moving velocities are found to increase with the coflow air flow rates. Besides flow visualisation based on high-speed schlieren imaging sequences, the velocity fields during ignition process have been evaluated quantitatively using optical flow method. [ABSTRACT FROM AUTHOR]

A pore network (PN) model is developed to explore drying of a thin hydrophobic porous medium bounded with a gas purge channel. The PN is composed of cubic pore bodies connected by cylindrical pore throats. At the interface between a pore throat and body, a sudden geometrical expansion exists. When a meniscus advances to this interface, it will be pinned first until the pressure across the meniscus increases to a critical value. This phenomenon is called the capillary valve effect. Because of this effect, two types of invasion into pore bodies are discerned, i.e. bursting and merging invasion. The developed PN model with the capillary valve effect is validated against the experimental results. For the drying case of dominant merging invasion, a drying front of finite width is stably receded. But when bursting invasion dominates, gas invasion is a random process; the drying process can be characterized by three regimes: a surface evaporation period, a constant rate period, and a falling rate period. The total liquid saturation for transition from the constant to falling rate period is close to that at which the total area for vapor transport is maximal between the partially filled pores and their neighboring empty pores. [ABSTRACT FROM AUTHOR]

Radiation absorbers are vital components in energy conversion and detection devices such as solar cells, thermal absorbers, photodetectors and biological sensors. Recently, layered absorbers with ultrathin films have attracted increasing attentions considering the good tradeoff between high absorption ability and low cost of simple structures. Although some theories have been proposed to understand absorption enhancement by introducing ultrathin films, few of them explicitly show effects of thicknesses and materials for perfect absorption. In this manuscript, the perfect absorption in layered absorbers is attributed to admittance matching by adjusting the loss factor of artificial magnetic conductors. Realistically, unified theories based on admittance analyses are developed to achieve perfect absorption in these absorbers. Admittance matching conditions related to thicknesses and materials for multilayer layered absorbers are deduced to achieve perfect absorption. Thus optimal film materials or thicknesses of films can be obtained directly. Moreover, admittance loci diagrams are employed to clearly illustrate influences of both material properties and structural parameters on radiative behaviors. Therefore, unified analyses are not only used as explanations for absorption mechanism, but also used as practical tools for the optimization of layered absorbers with ultrathin films. [ABSTRACT FROM AUTHOR]

Reversible reactions exhibit considerable potential for thermal energy storage because of their high energy density and capability for long-term storage at ambient temperature. This paper presents the research progress on gas–solid thermochemical heat storage reactors and their corresponding systems. The comprehensive state-of-the-art knowledge on gas–solid thermochemical reactors, namely, packed bed, continuous, and direct-type reactors, for high-temperature heat storage applications is reviewed. Up till now, the performance of packed bed reactors has been extensively investigated. However, the intrinsic drawbacks of packed bed reactors limit their applications. Continuous and direct-type reactors can efficiently store heat, but studies on these reactors are still on the stage of material characterization and prototype designing. Various numerical studies have successfully predicted the reaction trends in the three reactors to elucidate their performances and features. In these studies, porous thermochemical materials are studied on the scale of representative element volume. So far, numerical or experimental approaches have been rarely used to investigate physical and chemical processes at the particle scale. Energy and exergy analyses on conceptual thermochemical heat storage systems came into existence recently. In the future, more efficiency analyses based on practical experimental results are required. [ABSTRACT FROM AUTHOR]

Silicon nanowires have large aspect-ratio to keep high absorption along the incident direction, so nanowire arrays are one of potential structures for trapping light. To further enhance absorption in silicon nanowire arrays, thin blocks are arranged on the silicon substrate. It numerically demonstrates that additional blocks not only have few negative influence on absorption of nanowire arrays in the visible range, but also excite extra resonances in the near-infrared range, which make grading absorption and enhancement in the nanostructures. These excited resonances are finely examined and attributed to surface plasmon polaritons, guided modes and their coupled modes. The enhancement mechanism is further revealed by the electromagnetic fields and theoretical analysis for corresponding two-dimensional structures. The nanostructures can achieve higher absorption in silicon nanowire arrays, and grading absorption in the nanostructures will facilitate the development of other devices as novel filters, photoelectronics and so on. [ABSTRACT FROM AUTHOR]

This paper introduces a novel nano phase change material emulsion (NPCE) which was synthesized by direct miniemulsion method. A series of NPCEs using n -octadecane as phase change material were prepared with 10 wt.%, 20 wt.%, 30 wt.% and 40 wt.%, respectively. Prepared NPCEs were characterized by particle size analyzer, transmission electron microscopy (TEM), differential scanning calorimeter (DSC), thermal conductivity meter and rheometer. The TEM image shows that all the NPCEs are successfully synthesized with well dispersed nanoparticles. The DSC results indicate that the melting behaviour of n -octadecane is close to NPCEs and the supercooling is observed in all the NPCEs. Particle size and rheological analyses demonstrate that prepared NPCEs present a narrow size distribution and an extreme stable form. In comparison with the conventional phase change material slurry (PCS) and microencapsulated phase change material slurry (MPCS), the NPCE tends to be much more stable and importantly it can be synthesized in a cost-effective form in terms of method and materials. [ABSTRACT FROM AUTHOR]

Cyclic stability is a key factor in the design of thermochemical heat storage systems. Because carbon dioxide (CO 2 ) may react with heat storage materials and lead to a decrease in energy storage efficiency, the effect of CO 2 on Ca(OH) 2 /CaO and Mg(OH) 2 /MgO systems is investigated in this study. The experimental results show that CO 2 reacts with CaO in the water vapor that appears during the heat release process. Therefore, in the design of Ca(OH) 2 /CaO systems, CO 2 should be cleared from the system. The results from Mg(OH) 2 /MgO systems show that CO 2 only slightly reacts with MgO and Mg(OH) 2 during heat storage and release processes. This study indicates that carbonic acid (H 2 CO 3 ) could easily react with CaO/Ca(OH) 2 to form CaCO 3 during heat release processes. Generally, the remaining CO 2 reduces the reversibility of Ca(OH) 2 /CaO systems but has only a slight influence on Mg(OH) 2 /MgO systems. In addition, the experimental results show that carbonate shell does not exist in rehydration for both of the CaO/MgO samples, but the influence of CO 2 on the entire process increases after each cycle. [ABSTRACT FROM AUTHOR]

In this study calcium nitrate, sodium nitrate, and potassium nitrate were mixed to form cheap ternary molten salts based on different weight ratios. These molten salts can be used as both sensible heat storage materials and latent heat storage materials. In addition, they can be directly used as heat transfer fluids due to their low freezing temperatures. The results indicated that the mixture (Ca(NO 3 ) 2 :NaNO 3 :KNO 3 = 32:24:44 wt%) had the best performance for latent heat storage with its enthalpy of 67 J/g and melting point of about 80 °C. The specific heat capacity (1.7 J/(g °C) for the solid phase and 1.2 J/(g °C) for the liquid phase), viscosity (next to zero at 200 °C), thermal conductivity (about 1–3 W/(m K)), thermal decomposition, and cycle stability of the molten salts were measured by DSC, Malvern Kinexus Ultra + , a transient plane thermal conductivity meter, STA, and XRD, respectively. The thermophysical properties including the low manufacturing cost showed that the molten salts have great potential applications in thermal storage systems. [ABSTRACT FROM AUTHOR]

Cascaded latent thermal storage is an efficient technique for balancing the gap between demand and supply in renewable energy utilization. In this work, the steady cascaded thermal storage system with multiple phase-change materials (PCMs) of different phase-change temperatures is theoretically optimized from the viewpoint of thermodynamics. Analytical solutions for optimal temperatures of heat transfer fluid (HTF) and PCMs are obtained based on entropy and entransy concepts. The corresponding qualifications for optimization solutions are also discussed. With an increase in stage number or that in NTU , both thermal and exergy efficiencies increase. Compared with single-stage thermal storage, the cascaded thermal storage with multiple PCMs can not only improve the thermal performance, but also extend the application scope of thermal energy with multi-grade thermal energies provided. The temperature distribution for HTF and PCMs with entransy optimization is linear, while that with entropy optimization is geometric progression. The application situations of entropy and entransy in thermal energy utilization are identified by comparing optimal result based on entropy with that based on entransy. This optimization can not only be used to establish the steady cascaded thermal storage system, but also guide the filtration of PCMs used in such systems. [ABSTRACT FROM AUTHOR]

Cascaded latent thermal storage can find its applications in renewable thermal energies with time-dependent temperatures. This paper presents thermal performance of cascaded heat storage with unsteady inlet temperature of heat transfer fluid (HTF). The optimization of temperatures of HTF and phase-change materials (PCMs) is performed based on exergy, entropy, and entransy. Corresponding analytical/numerical solutions with these concepts are obtained. The qualifications for existence of optimization solutions are proposed. The optimization result of unsteady case is compared with that of steady case. The fluctuation of HTF temperature is transferred along the HTF flow path. The HTF temperatures in different stages exhibit similar fluctuating trend, but the fluctuating amplitude is diminished along the HTF flow path. With an increase in stage number, the difference between temperatures of outlet HTF and environment is gradually decreased with obviously improved thermal performance. As NTU increases, thermal performance is gradually increased, but with decreased increasing amplitude. The optimization result with entransy is also compared with that of entropy. The optimal exergy efficiency based on entropy is greater than that based on entransy, while the optimal thermal efficiency based on entransy is superior to that based on entropy. The optimization can be applied to select PCMs for unsteady cascaded thermal storage. [ABSTRACT FROM AUTHOR]

Aiming at promoting the fundamental understanding on relationship between the radiative transfer mechanism and microstructure of thermal barrier coatings (TBCs), here in this study, we numerically demonstrate the anisotropy of radiative properties of air plasma sprayed (APS) TBCs for the first time. The anisotropic microstructures of APS TBCs are quantitatively reconstructed based on Ultra-Small-Angle X-Ray Scattering (USAXS) measurement by the Stony Brook University group ( Li et al., J . Amer . Ceram . Soc ., 92(2) p . 491–500 , 2009 ), in which the microscale pores and cracks are treated as oblate spheroids with a preferred distribution of orientations. The anisotropic mesoscopic radiative properties, including scattering coefficient/mean free path and asymmetry factor, are computed using the discrete dipole approximation (DDA) to solve Maxwell's equations. To fully depict the effect of anisotropy on radiative transfer in a macroscopic scale, a random walk scheme is thus proposed to solve the anisotropic radiative transfer problem in such medium, and the macroscopic transport mean free path describing energy diffusion process is derived. Results are further compared with those under isotropic assumption. By considering external blackbody as thermal radiation sources for the coating, we show that anisotropy of radiative properties affects the transmitted radiative heat flux across it considerably, especially at high operating temperatures and for thick coatings. On the other hand, in moderate operating conditions, the simplistic approach can also give an acceptable approximation on heat transfer for the presented particular coating microstructure. The present work provides a fundamental framework for studying radiative transport in anisotropic porous media. [ABSTRACT FROM AUTHOR]

• Realizing tailorable bandgap-dependent selective emitters based on metasurfaces. • Selective emitter with excellent spectrally selectivity, polarization-insensitive, and angle-insensitive features. • Tunable cutoff wavelength by adjusting the geometries of nanodisks of the metasurface. • The efficiency of TPV system can be expected to be 27% at 1473 K. Selective emitters are crucial in thermophotovoltaic (TPV) systems as they can selectively tailor the incident light to match with the bandgap of photovoltaic (PV) cell, thus greatly increasing the system efficiency. However, further progress has been hampered by the limitation in designing high performance selective emitters with spectrally emissive selectivity and compatible ability to different PV cells. In this study, we propose a design strategy to realize tailorable bandgap-dependent selective emitters based on metasurfaces by combing the two-resonance response of surface plasmon polaritons (SPPs) and magnetic polaritons (MPs). The emission spectrum can be manipulated and matched to various PV cells with different bandgap by simply changing the size and period of the meta-atoms in metasurface. We design and experimentally demonstrate a selective emitter appealing to GaSb PV cells, which presents near-perfect emissivity (above 0.96) above the bandgap wavelength (from 0.9 μ m to 1.54 μ m) with polarization-insensitive and angle-insensitive features. Moreover, the emitter shows a high figure of merit (FOM, of 0.85), and the efficiency of TPV system can be expected to be 27% at 1473K. The proposed strategy and designed emitter may pave a reliable route for improving the performance of TPV systems. [ABSTRACT FROM AUTHOR]

• Brayton-like pumped-thermal electricity storage based on latent heat/cold stores is introduced. • The rated power of the system is 150 kW and the charging/discharging time is 4 h. • The dimensionless analysis is applied to the energy storage units for generality. • The energy density of the optimized system using PCMs can reach 267.4 kWh/m3. • The roundtrip efficiency of the system can reach 0.55. Pumped-thermal electricity storage has the advantages of high energy storage density, no geographical restrictions and low costs, making it the most promising large-scale electricity storage technology. In this paper, a numerical model of the Brayton-like pumped-thermal electricity storage based on packed-bed latent heat/cold stores is established and a recuperator is added between the hot store and the expander. The rated power of the system is 150 kW and the charging/discharging time is 4 h. The dimensionless analysis is applied to the energy storage units including transient temperature, charging/discharging time as well as axial position. Moreover, based on the finite element method, an extensive thermodynamic analysis is carried out in MATLAB. It is concluded that compared with the non-recuperated system, the total input power of the recuperated system can be reduced by 18.1 kW in the charge duration and the energy density of the system using PCMs instead of sensible heat storage materials can be improved from 202.4 kWh/m3 to 267.4 kWh/m3. The roundtrip efficiency of the system could reach 0.55. In addition, detailed exergy flow and exergy loss of each component are studied. It is found that the total exergy loss of the recuperated system is 52.27 kW, a 22.4 % decrease compared to that of the non-recuperated system and the compressor has the largest exergy loss, accounting for 36 % of the total loss, which can be ameliorated by improving the level of industrial manufacturing in the future. [ABSTRACT FROM AUTHOR]

A numerical study on the solid–liquid phase change in open-cell metal foams is carried out by the phase field method originated from the Ginzburg–Landau theory. The Brinkman–Forchheimer extended Darcy equation and the local thermal non-equilibrium model are adopted to take natural convection and the heat transfer between metal foams and phase change materials (PCMs) into consideration, respectively. The result proves that the phase field model is reliable and effective in modeling metal foam enhanced phase change heat transfer in thermal energy storage. The effects of key parameters, such as Rayleigh number, porosity and pore density, on the melting and solidification process are investigated and it is found that they have great influence on the solid–liquid phase change. The phase field, flow field and temperature distributions in the melting and solidification process are obtained. Furthermore, kinetic undercooling in the solidification process is studied. It is concluded that heat conduction through the ligament of metal foams plays a dominant role in the solid–liquid phase change and kinetic undercooling effect is weakened as kinetic coefficient decreases. [ABSTRACT FROM AUTHOR]