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SLM methods are widely used to manufacture metal parts for functional use in mainly automotive, aerospace and medical industries. Besides many advantages of SLM, manufacturing times take long times and need many costs. In this study, nine samples were manufactured at the same time to set a scenario of multiple samples manufacturing and providing highly productive conditions. Some manufacturing problems such as internal stresses and dimensional distortions occurred during manufacturing. These problems were the result of heterogeneous temperature gradients and geometrical properties. FEA studies were carried out by “Netfabb Ultimate Simulation LT 2019”. Temperature changes were observed, and relations among these temperature changes, residual stresses, as well as dimensional distortions were evaluated. As a result, the orientation distance of samples was an important parameter due to residual stress and displacement. Unsuitable positioning distance between samples caused high dimensional distortion, macro cracks and residual stress. The plastic strain equation was correlated according to the results of the analysis with 7% difference (regression) to define the optimum distance between parts.

In this work, solar-heating-induced temperature-based photocatalytic hydrogen evolution reaction (PC-HER) of different photocatalysts (TiO2 P25, g-C3N4, and their loaded Pt) was comprehensively stu...

Lead zirconate-lanthanum magnesium niobate (Pb(1-x)Laх[Zr(1-x)Mg2х/3Nbх/3]O3) solid solutions with x up to 10 mol.% have been obtained by solid phase synthesis method. It has been found that solid ...

The temperature-dependent structure and properties of a liquid GaInSn eutectic alloy have been investigated by using in situ high-energy X-ray diffraction, thermal expansion, and heat capacity meas...

The structures of the equiatomic stannides RERhSn with the smaller rare earth elements Y, Gd-Tm and Lu were reinvestigated on the basis of temperature-dependent single crystal X-ray diffraction data. GdRhSn crystallizes with the aristotype ZrNiAl at 293 and 90 K. For RE = Y, Tb, Ho and Er the HP-CeRuSn type (approximant with space group R3m) is already formed at room temperature, while DyRhSn adopts the HP-CeRuSn type below 280 K. TmRhSn and LuRhSn show incommensurate modulated variants with superspace groups P31m(1/3; 1/3; γ) 000 (No. 157.1.23.1) (γ = 3/8 for TmRhSn and γ = 2/5 for LuRhSn). The driving force for superstructure formation (modulation) is a strengthening of Rh–Sn bonding. The modulation is expressed in a 119Sn Mössbauer spectrum of DyRhSn at 78 K through line broadening.

Application of cold storage temperatures below optimum induces a high risk and threat of chilling injury (CI) in the case of sensitive commodities. Sweet pepper belongs to this group of vegetables, so our main objective was to investigate and monitor the effect of non-optimal temperatures (2.5 and 5 °C) induced stress (chilling injury) on kápia type sweet pepper (Capsicum annuum L.) during its postharvest storage by nondestructive quality measuring methods. Fresh, semi-matured (reddish-green colored) samples of ‘Kapitány F1’ cultivar were stored at 2.5, 5 and 10 °C for 7 d followed by 7 d shelf-life. Nondestructive texture measurements were carried out by a purpose built tabletop acoustic stiffness device. Surface color and chlorophyll content related quality indices were evaluated by a chroma meter, a DA-meter® and a chlorophyll fluorescence imaging system. High resolution digital pictures were captured and analyzed for possible CI defects by means of surface color values (normalized RGB, hue and saturation). According to our results, the evaluated quality indices (DA-index®, acoustic stiffness coefficient, surface color parameters; F0, Fm, Fv and Fv/Fm chlorophyll fluorescence parameters) clearly represented the temperature dependent quality changes during low temperature storage, subsequently followed by ambient shelf-life. Samples stored under and at 5 °C showed the chilling temperature stressed symptoms of delayed and partly retarded postharvest ripening, even under simulated shelf-life conditions, but without the onset and manifestation of the characteristic visible symptoms of chilling injury. This may raise doubts and suggest possible future research areas regarding the role of non-optimal cold storage temperatures induced stress, the effect of chilling injury contributing factors and consequences.

Background The present study attempted to demonstrate how the configuration of hydrogel-coated coils is influenced by different temperature exposures. Thirty detachable hydrogel-coated coils were evaluated in an in vitro water immersion test under five different temperature ranges (22.6 °C, 37 °C, 40–50 °C, 50–60 °C, and 60–70 °C). The configuration changes were classified (configuration I, configuration II, and configuration III) according to the curling that occurred during 30 min of immersion. Configuration stability of five Hydrogel-coated coils was also evaluated in a two-step temperature immersion test. Results All hydrogel-coated coils showed some configuration changes during water immersion. However, a logarithmic transformation of the time and temperature data showed a significant (p R = 0.97, configuration II: R = 0.98, configuration III: R = 0.97). The time needed to reach configuration III (complete coiling) was 160.4 ± 41.9 s at 37.5 °C (range: 100–205 s), 45.7 ± 22.2 s at 47.5 °C (range: 23–70 s), 20.2 ± 7.2 s at 57.5 °C (range: 14–32 s), and 10.3 ± 2.4 s at 67.5 °C (range: 7–13 s). Conclusions Temperatures above 55 °C induced immediate configurational changes in the hydro-coated coils, achieving complete curling within less than 30 s. Temperatures near 36 °C (normal body temperature) require more time to reach optimal coil curling (configuration III). The optimization of HydroCoil preparation can reduce interventional procedural time and improve clinical results.

Heterointerfaces coupling complex oxides exhibit coexisting functional properties such as magnetism, superconductivity, and ferroelectricity, often absent in their individual constituent. SrTiO3 (STO), a canonical band insulator, is an active constituent of such heterointerfaces. Temperature-, strain-, or mechanical stress-induced ferroelastic transition leads to the formation of narrow domains and domain walls in STO. Such ferroelastic domain walls have been studied using imaging or transport techniques and, often, the findings are influenced by the choice and interaction of the electrodes with STO. In this work, we use graphene as a unique platform to unveil the movement of oxygen vacancies and ferroelastic domain walls near the STO surface by studying the temperature and gate bias dependence of charge transport in graphene. By sweeping the back gate voltage, we observe antihysteresis in graphene typically observed in conventional ferroelectric oxides. Interestingly, we find features in antihysteresis that are related to the movement of domain walls and of oxygen vacancies in STO. We ascertain this by analyzing the time dependence of the graphene square resistance at different temperatures and gate bias. Density functional calculations estimate the surface polarization and formation energies of layer-dependent oxygen vacancies in STO. This corroborates quantitatively with the activation energies determined from the temperature dependence of the graphene square resistance. Introduction of a hexagonal boron nitride (hBN) layer, of varying thicknesses, between graphene and STO leads to a gradual disappearance of the observed features, implying the influence of the domain walls onto the potential landscape in graphene.

Highly accurate high-throughput experimentation (HTE) data for a set of 21 silicon-bridged C2-symmetric ansa-zirconocenes in propene homopolymerization were collected and were used to develop quant...

The interaction between bending and shear effects in steel beams can be amplified under fire conditions due to rapid degradation in strength and stiffness properties of steel, together with temperature-induced local instability effects. This paper presents temperature-induced moment-shear (M-V) interaction phenomenon in compact (Class 1) steel beams. Results generated from numerical studies are utilized to quantify the effects of temperature-induced critical parameters influencing moment-shear interaction, shear and flexural sectional capacity, as well as instability in steel beams under fire conditions. The major findings of this work are two folds: (1) occurrence of temperature-induced instability adversely reduces shear capacity, as compared to flexural capacity, and (2) this rapid degradation in shear capacity trigger moment–shear interaction phenomenon at elevated temperatures. Eventually, this shifts failure mode in steel beams towards a shear dominant failure mechanism on the interaction envelope.

We present a detailed case study of degradation in monocrystalline silicon photovoltaic modules operating in a utility-scale power plant over the course of approximately three years. We present the results of degradation analysis on arrays within the site, and find that five of the six arrays degraded faster than the best performing array, even though the arrays consist of modules of the same manufacturer and model. We also describe the results of extensive laboratory characterization of modules returned from the field, including module- and cell-level current–voltage characterization, luminescence imaging, and accelerated testing. The laboratory test results and the field performance are consistent with light and elevated temperature induced degradation (LeTID). Notably, we observe differences in back contact technology between affected and unaffected modules. This article also demonstrates a method to identify possible LeTID degradation in the field and confirm the result with laboratory testing of a small number of modules.

We have studied lifetime instabilities in p -type boron-doped mono-like silicon during light soaking (LS) and dark annealing (DA) at different temperatures, and their behavior upon LS/DA cycling at various degradation and regeneration stages. Despite having similar capture cross section ratios, it is found that the defects responsible for the degradation under illumination and in the dark could stem from two separate reactions, with hydrogen being the common precursor. A model for light and elevated temperature induced degradation (LeTID) is presented based on our experimental findings. It is proposed that hydrogen atoms originally bound in the silicon nitride layer are released into the silicon bulk above a certain firing temperature, which then interact with some other species in the silicon bulk under illumination, causing the LeTID degradation. During the cooling ramp of the firing process or extended DA, hydrogen in the silicon bulk starts to effuse into the ambient, reducing the amount of hydrogen remaining in the silicon bulk, and correspondingly affecting their LeTID behavior. The proposed model provides new insights to help understand complex LeTID behaviors reported in the literature, including its dependence on the firing profile, sample thickness, dopant type, and DA pretreatment.

The precise structure of nanocrystal (NC) solids is a delicate balance between energetic and entropic interactions. Studying the temperature-dependent structure of NC solids can inform understandin...

In this study, the effects of the single and multiple productions of samples by additive manufacturing on residual stress and displacement (distortions) were investigated. The samples were manufactured by Selective Laser Melting (SLM) machine using Ti6Al4V powders. Each time a different number (1, 5 and 13 samples) of cubic shaped samples were produced on the building platform. During the process, samples were observed with a thermal camera first, in order to understand the relationship amongst the residual stress, displacement and temperature gradients. Then, displacement values were measured experimentally with Coordinate Measurement Machine (CMM) device. Next, both displacement and residual stresses were calculated via Finite Element Analysis (FEA) method. Finally, residual stresses and displacement equations were determined by genetic expressional programming (GEP) using the results and data obtained from the tests and FEA. According to the results, the regression values of residual stress and displacement equation were found to be 0.96% and 0.88%, respectively. As the number of manufactured samples on the same platform increased, temperatures and irregular temperature distribution were increased.

Specimens for transmission electron microscopic (TEM) investigations were prepared from γ titanium aluminide alloys with Gallium and Argon ions using a focused ion beam (FIB) and a precision ion polishing system (PIPS). Preparation to electron transparency by Gallium ions alone leads to the formation of crystalline platelets of the α titanium phase at the specimen surfaces, revealed through conventional and high resolution (HR) TEM analysis. The platelets are assumed to precipitate from priorly formed amorphous layers. The required crystallisation temperature of about 480°C is generated through the ion bombardment implying that the γ titanium aluminides can be heated substantively during sputtering. The primary reason for this is the restricted transfer of heat away from the beam impact point when the specimen thickness comes close to the beam diameter. The formation of the platelets can be avoided by terminating the Gallium ion treatment prior to that, while providing for a sufficient thermal bonding of the specimen to the grid as well and polishing off the remaining material by Argon ions, which are much less focused and less energetic, so that the local heat peaks are reduced.

A mechanism to explain the lower onset strengthening temperature induced by CaCO$_3$ in alumina-based macroporous ceramics is proposed, which relies on hydrocalumite-like phase formation during processing. Close to 600$^\circ$C, such phases are decomposed to lime and mayenite (12CaO$\cdot$7Al$_2$O$_3$), where the latter, due to its intrinsic nanoporosity and high thermal reactivity, generates bonds between the ceramic particles at ~700$^\circ$C, resulting in microstructure strengthening. Based on this premise, the authors concluded that other Ca$^{2+}$ sources could act similarly. Indeed, compositions containing Ca(OH)$_2$ or CaO showed the same effect on the onset strengthening temperature, which reinforces the proposed mechanism. The results attained indicated that macroporous insulators could be thermally treated at lower temperatures, just to acquire enough mechanical strength for installation, finishing in situ their firing process. Besides that, lower sintering temperatures could be used to produce macroporous ceramics that would be applied in low thermal demand environments, e.g. aluminum industries.

Hybrid organic-inorganic FAPbX3 perovskites (FA = NH2CHNH2+, X = Cl-, Br-, I-) are currently intensively investigated in solar cells. In this study, off-resonance Raman and far-IR absorption spectr...

A robust, yet flexible, Al-based metal-organic framework (MOF), Al2(OH)2(bpydc)·0.5H2O (1np), is synthesized via a hydrothermal strategy utilizing 2,2′-bipyridine-5,5′-dicarboxylate (bpydc2–) as th...

An evaluation of the degradation effects on photovoltaic modules is essential to minimise uncertainties in the system operation. Bifacial photovoltaic technology is attracting attention due to the capacity of generating energy from the front and rear sides. This paper presents a review of degradation factors, for both conventional monofacial and bifacial photovoltaic modules, to highlight how the current and voltage characteristics of these technologies are affected by degradation. Microcracking, encapsulant discoloration, and light induced degradation seem to have similar effects on both modules. Contrarily, bifacial modules are more prone to potential induced degradation as the electromagnetic shielding is affected by the bifaciality. Bifacial devices are less affected by light and elevated temperature induced degradation. The degradation (1.3%) is similar for both technologies, up to 40 kWh/m2 of solar radiation. Above this value, monofacial degradation increases faster, reaching values of 7%. For tilted systems, the front side soiling degradation of 0.30% per day is similar for both technologies. For vertical systems, soiling loss for bifacial is considerably lower with values of 0.02% per day.

We report a highly stable Zn metal anode by simply controlling the operating temperature at 0 °C. Without any further protection, the Zn anode exhibits an ultra-long cycle life over 2500 h (>100 days) in Zn symmetric cells with 3 M Zn(CF3SO3)2 aqueous electrolyte. This impressive performance is ascribed to the improved Zn metal corrosion resistance and compact and smooth Zn surface morphology during Zn plating/stripping at low temperatures.

A series of polyimide (PI) films with a high-temperature-induced shape memory effect and tunable properties were prepared via the facile random copolymerization of 4,4′-oxydianiline (ODA) with 4,4′-(hexafluoroisopropyl)diphthalic anhydride (6FDA) and 4,4′-oxydiphthalic anhydride (ODPA). The trigger temperature can be controlled from 294 to 326 °C by adjusting the ratio of monomers. The effects of monomer rigidity on the chain mobility, physical properties, and shape memory performance of as-prepared copolyimide were systematically investigated. The introduction of ODPA could enhance the mobility of PI macromolecular chains, which made chain entanglement more likely to occur and increased the physical crosslinking density, thereby improving the PI’s shape recovery up to 97%. Meanwhile, the existence of 6FDA enabled PI films to set quickly at low temperatures with a shape fixation of 98%. The shape memory cycling characteristics of the polyimide films are also studied, and the relationship between the PI chemical structure and the film properties are further discussed.

To simplify the implementation of photoelasticity studies, the recently introduced Thermal Transient Stepping (TTS) method produces a stress field, from images with fringe displacements induced by temperature. These images are acquired without using mechanically-induced load variations, nor rotating optical devices. However, TTS produces stress fields with unwrapping errors, due to the lack of a strategy to select adequately the fringe displacements. We addressed this limitation by evaluating different thermal stimulations, and their effects in the performance of TTS. This allows us to achieve stress fields with higher fringe orders.

International audience; One of the causes of decrease in the performance of silicon-based solar pannels is linked to light and elevated temperature induced degradation (LeTID). Even if experimental evidence shows that different defects in the bulk material of the modules are involved in the mechanisms behind LeTID, its origins remain unresolved. First-principles methods result in powerful tools to understand this degradation at the nano and microscopic levels. In the present work we propose an approach to model LeTID precursors mechanisms by using ab initio methodology.

This study presents aging of backsheet materials that were stored for 17 years in the dark at room temperature. The material properties were measured and compared to the results from right after production. After 17 years of storage the strain at break values decreased significantly for all materials. As chemical aging phenomena were excluded, a disentanglement of the polymer chains in the amorphous phase would explain the observed changes. Especially for PVDF the change in the mechanical behavior is considered as very critical and possibly would lead to cracking during operation.

Supramolecular polymerization of nanoscale particles has been considered as an effective route to prepare hierarchical nanostructures with controlled geometry and functions. However, so far, less i...

Thermoresponsive interpenetrating networks (IPNs) were prepared by sequential synthesis of a biohybrid network of star-shaped poly(ethylene glycol) [starPEG] and heparin and a poly(N-isopropylacryl...

Nanocomposite thin film containing Au nanoparticles in carbon matrix is developed using co-sputtering method in a high vacuum chamber (

Optical lenses used in high temperature environment are usually affected by thermal lenses problems, but it is difficult to evaluate their focal shifts in practical applications. A three-dimensional single-lens model based on finite element solver was built to evaluate the focal shift in this study, when the temperature of surface was raised from the initial temperature to the specified temperature. An experimental method based on a Hartmann-Shack wavefront sensor was proposed to verify the rationality of the model. The nearly same results between simulations and experiments for N-BK7 and fused silica were obtained, which proves that it is feasible to analyze focal shifts of optical lenses by simulation methods.

We provide experimental evidence that photoalignment at the nematic liquid crystal (NLC)-polymer interface cannot be simply considered as a two-dimensional process. Moreover, our experiments clearly indicate that the photoaligning process does not depend on the individual properties of the NLC material and those of the interfacing polymer exclusively. The polymer and the NLC layer interact, i.e., the polymer-liquid crystal interface should be regarded as a coupled system, where the two components mutually influence each other. Furthermore, we show that the temperature induced anchoring transition also has to be taken into account for the complete description of the photoalignment mechanism.

Two techniques for the nucleation and growth of single crystals of biological macromolecules are proposed. The first one utilizes a very slow temperature shift at a capillary point where the crystal is to be grown. This allows to suppress an undesirable multiple nucleation. The second technique includes several local rapid temperature changes (a temperature “shock”) forcing the nucleation at the given point. These techniques were successfully tested while growing single crystals of lysozyme and xylanase respectively.

Three different stir tools with the pin eccentricity of 0, 0.4 and 0.8 mm were applied to the friction stir processing (FSP) of Al-6061 alloy. Results show that the pin-affected zone (PAZ) enlarges and the grain size in the stir zone (SZ) decreases as the pin eccentricity increases. Moreover, the low peak FSP temperature induced by the pin eccentricity gives rise to the coarsening of strengthening precipitates in the SZ. Compared with the pin-eccentric FSP samples, the SZ produced without pin eccentricity exhibits the highest hardness and yield strength due to the high amount of fine precipitates. However, the application of pin eccentricity elevates the overall tensile properties of FSP samples through changing the failure location from heat-affected zone (HAZ) to SZ.

Owing to its thermal conductivity property, the strength of structural steel is highly susceptible to elevated temperature. When steel is used in main load-bearing members in buildings that are vulnerable to fire, great attention should be paid to the effect of the elevated temperature on the residual strength of those members. Hence, the design criteria of such members must incorporate temperature in their requirements. Current standards and codes of practice for steel structures have attempted to address the elevated temperature in their design procedures. However, the design procedures suggested by these standards and codes still lack accuracy and rationality compared to experimental results, especially at high values of elevated temperature. The main objective of the present study is to suggest a new and accurate analytical method to reasonably predict the residual axial and lateral strength of steel beam columns when subjected to elevated temperature. The suggested method uses a newly derived moment-curvature equation of steel beam columns at elevated temperature. The effect of elevated temperature on the material and mechanical characteristics of the steel was accounted for by utilizing reduction factors suggested by Eurocode 3 (EC3). Validation of the suggested method against experimental and numerical simulation results has demonstrated that the developed method can reasonably predict the residual axial and lateral resistance of steel beam-columns at high values of elevated temperature. The suggested method has many significant applications in the design of steel members at elevated temperature induced by fire.

The aim of this study was to develop a fast and an efficient method to determine the Hydrophile-Lipophile Balance (HLB) number of cosmetic and pharmaceutics surfactants.This method is based on the deviation of the phase inversion temperature induced by the addition of the test compound, with respect to the phase inversion temperature of a reference system, which includes an ethoxylated surfactant. This method is called PIT-deviation.Three calibration curves are set up with three reference ethoxylated surfactants. These calibration curves make it possible to evaluate the interfacial behaviour of certain chemicals. More particularly, these curves make it possible to easily determine the surfactant HLB.In this study, a fast and accurate method has been developed to determine the hydrophilic-lipophilic balance (HLB) number of amphiphilic chemicals. This new method can be applied to establish an HLB number of all commercial amphiphilic ingredients. Compounds which have a PIT-deviation close to zero are also discussed.Le but de cette étude était de développer une méthode rapide et efficace pour déterminer le nombre Hydrophiles-Lipophiles Balance (HLB) d'agents tensioactifs cosmétiques et pharmaceutiques. MÉTHODES: Cette méthode est basée sur le déplacement de la température d'inversion de phase induite par l'addition du composé à tester par rapport à la température d'inversion de phase d'un système de référence, comprenant un tensioactif éthoxylé. Cette méthode s'appelle PIT-déviation. RÉSULTATS: Trois courbes d'étalonnage sont établies avec trois tensioactifs éthoxylés de référence. Ces courbes d'étalonnage permettent d'évaluer le comportement interfacial de certains produits chimiques. Plus particulièrement, ces courbes permettent de déterminer facilement le HLB de tensioactif.Dans cette étude, une méthode rapide et précise a été développée pour déterminer le Hydrophile-Lipophile Balance (HLB) de produits chimiques amphiphiles. Cette nouvelle méthode peut être appliquée pour établir un HLB de tous les ingrédients amphiphiles. Les composés dont la PIT-deviation est proche de zéro sont également abordés.

The heat capacity Cp is calculated from the temperature-induced and pressure-induced Raman frequency shifts by means of the mode Gruneisen parameter for the I-II transition of solid benzene, naphthalene and anthracene. For this calculation, contributions to Cp are considered due to the six lattice modes of solid benzene, six librational modes of naphthalene and, six phonons and nine vibrons of anthracene with their mode Gruneisen parameters at various temperature (P=0) and pressures (T=300 K). Our calculated Cp explains the observed behavior of the I–II transition in solid benzene and also of naphthalene and anthracene. Temperature dependence of the entropy difference is calculated from the heat capacity for those hydrocarbons, which can be compared with the observed data. Our results indicate that the heat capacity Cp can be calculated as functions of temperature and pressure from the spectroscopic parameters, in particular, the Raman frequency shifts as we have studied here for hydrocarbons.

The pressure-dependent electronic properties of polycrystalline β-Ag0.33V2O5 were investigated and a discontinuous change of electrical resistance is found at around 4.5 GPa, where semiconductive-like decreasing trend before 4.5 GPa and a metallic-like increasing trend after 4.5 GPa with increasing temperature was observed. Furthermore, high temperature/pressure treatment can markedly reduce the semiconductor-metal (S-M) transition pressure to around 1.5 GPa. The results indicate a promising way for engineering the electronic properties of polycrystalline Ag0.33V2O5, and this pressure/temperature induced semiconductor-metal switch may have potential applications in electronics field.