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Controlling reactions in crystalline solids provides new opportunities in synthetic chemistry and materials science. Much effort has been devoted to using non-covalent interactions (e.g., hydrogen bonding, halogen bonding and metal coordination) to direct the formation of covalent bonds in photoactive solids. In this case, use of small organic molecules (e.g., resorcinols) as templates to assemble reactants (i.e., olefins) in a desired geometry for a [2+2] photodimerization continues to draw research interest. While tremendous progress has been made in the field during the past two decades, additional studies are essential to expand the toolbox of non-covalent interactions to enable the design and synthesis of functional solid materials as well as structurally diverse molecular building blocks. Moreover, achieving single-crystal-to-single-crystal (SCSC) reactivity and rapid functional group diversification of the photoproduct remains challenging., The dissertation addressed the challenges using principles of supramolecular design and crystal engineering strategies. In doing so, aryl nitriles, one of most versatile functional groups in organic synthesis, were introduced to serve a dual role as both hydrogen-bond-acceptors and modifiable organic functional groups. The programmable design was realized by preparing a bis(aryl nitrile) alkene that self-assembles with resorcinol by hydrogen bonding to form a photoreactive solid. The pre-organized bis(aryl nitrile) alkene went through an intermolecular [2+2] photodimerization to afford a tetra(aryl nitrile)cyclobutane stereoselectively and in 100% yield. The product is readily convertible to a tetra(aryl tetrazole) via click reactivity and a tetra(aryl carboxylic acid) via hydrolysis. We expect the reported method to pave the way for post-modifying products formed in crystalline solids for rapid diversification., As part of our efforts to synthesize structurally diverse molecular architectures, highly-symmetric cubane-like cages were synthesized stereoselectively and in quantitative yield through double [2+2] photodimerizations. A tetraacid cubane-like cage was constructed from a photodimerization of one of the cyclic dienes in cocrystal components. The second cyclic diene, while photostable in the cocrystal, reacts as a pure form quantitatively to form a tetramethyl cubane-like cage. In addition to three-dimensional (3D) organic cages, we fabricate one-dimensional (1D) DNA-like bundles and 3D networks in small-molecule drug-drug cocrystals. Specifically, cocrystals composed of antiretroviral drug lamivudine and cytotoxic chemotherapy drug 5-fluorouracil was synthesized in 1:1 and 1:2 ratios. The components of the cocrystals self-assemble through unusual pyrimidine⋯pyrimidine base pairing between the cytosine (C) ring of the non-phosphate nucleoside analog lamivudine and the uracil (U) base of the nitrogenous base analog 5-fluorouracil to form DNA-like supramolecular architectures., Non-covalent interactions lie at the core of supramolecular chemistry and crystal engineering. In this context, we integrated gold(I) coordination and aurophilic interactions to design and synthesize photoreactive tetranuclear gold(I) macrocycles. Within the metal-organic complex, C=C bonds are arranged in a favorable geometry for a photodimerization reaction. The photoreaction proceeds via a rare SCSC transformation that retains the crystallinity. The single-crystal reaction generates photoproduct stereoselectively and quantitively with new ramp-like features on the surfaces of single crystals. Additionally, we used a less common type of hydrogen bond in the form of N+-H···N to support a cascade-like [2+2] photodimerization in a salt cocrystal. The charge-assisted hydrogen bond and cation···π interaction sustain the formation of photoactive ionic assemblies that undergo a SCSC transformation to give cyclobutane product in head-to-tail (ht) orientation. The photodimerization of ionic assemblies rearranged the molecular geometry of the photostable assemble to become photoreactive. The outcome is the regiocontrolled formation of cyclobutane product in 100% yield.

Conventional Al-air battery has many disadvantages for miniwatt applications, such as the complex water management, bulky electrolyte storage and potential leakage hazard. Moreover, the self-corrosion of Al anode continues even when the electrolyte flow is stopped, leading to great Al waste. To tackle these issues, an innovative cotton-based aluminum-air battery is developed in this study. Instead of flowing alkaline solution, cotton substrate pre-deposited with solid alkaline is used, together with a small water reservoir to continuously wet the cotton and dissolve the alkaline in-situ. In this manner, the battery can be mechanically recharged by replacing the cotton substrate and refilling the water reservoir, while the thick aluminum anode can be reused for tens of times until complete consumption. The cotton substrate shows excellent ability for the storage and transportation of alkaline electrolyte, leading to a high peak power density of 73 mW cm−2 and a high specific energy of 930 mW h g−1. Moreover, the battery discharge capacity is found to be linear to the loading of pre-deposited alkaline, so that it can be precisely controlled according to the mission profile to avoid Al waste. Finally, a two-cell battery pack with common water reservoir is developed, which can provide a voltage of 2.7 V and a power output of 223.8 mW. With further scaling-up and stacking, this cotton-based Al-air battery system with low cost and high energy density is very promising for recharging miniwatt electronics in the outdoor environment.

Millimeter wave components, such as circulators and isolators, frequently use magnetic fields to break symmetry of the signal propagation and provide unidirectional signal transmission. While effective, these components have not seen the level of miniaturization of other millimeter wave components, primarily due to the discrete nature of the magnets used in the components. Using circulators in the 40-50 GHz range as a motivating application, requirements arise for the deposited films, namely immunity to eddy currents, sufficient magnetization to act as self-biasing magnets, and out-of-plane orientation of the self-biasing field. Based on these required properties, hexaferrite materials are selected for their strong magnetocrystalline anisotropy (MCA) and low conductance. The difficulty of integrating these components monolithically with monolithic microwave integrated circuits (MMIC) originates from the incompatibility of crystal structure with standard semiconductor materials and process conditions. Additive manufacturing using a composite of strontium hexaferrite (SrFe12O19) particles and photoresist has been chosen as a method to overcome the difficulties of integrating hexaferrite material to semiconductor substrates. Due to their large internal anisotropy field, the particles of strontium hexaferrite tend to rotate to the field direction instead of changing magnetization direction under application of an external magnetic field (less than the anisotropy field). We have developed a method for 3D printing composites of high strontium hexaferrite concentration (up to 20% by volume) in a liquid photoresist, SU8. Rotation of hexaferrite particles in polymer matrix and thus magnetic anisotropy has been demonstrated in the composite, which is subsequently cured to hold the physical position and orientation of the particles. The anisotropy of the self-biasing field provided by the films has been experimentally characterized, and a ferromagnetic resonance (FMR) frequency ~43 GHz has been observed. We have also characterized the viscosity of the particle-laden polymer at different particle concentrations. 3D printing of this composite with poling will make it possible to directly print magnetic components that require out-of-plane anisotropic magnetization.

Magnetic circuit components have long been the largest and most difficult components to miniaturize. Printed circuit board (PCB) fabrication methods cannot achieve small diameter, high aspect-ratio vias for high winding turn numbers to achieve high inductance, and microelectronics methods cannot achieve the high-quality and thick ferrite core materials. In this paper, we present an alternative breakthrough method of printed circuit fabrication to significantly reduce the effective via diameter for embedded magnetic devices, boosting the inductance per unit area. To reduce the effective via diameter, high-density via plugs are ex-situ fabricated and shaped, and then embedded into PCB substrate in the same process as standard magnetic core embedding. The structure of the plug is such that precise placement within the substrate, or alignment to the plug with the winding pattern, is not necessary. Devices presented in this paper use via plugs with an effective diameter of 40 μm and a theoretically unlimited aspect ratio, though refinements in the plug fabrication process are expected to reduce the via diameter down to 10μm. The process is experimentally demonstrated with a 14-turn racetrack shaped transformer; novel diagnostic methods using magneto-optic garnet films to image current paths are also demonstrated.

Metal-Organic Frameworks (MOFs) have been developed as solid sorbents for CO2 capture applications and their properties can be controlled by tuning the chemical blocks of their crystalline units. A number of MOFs (e.g., HKUST-1) have been developed but the question remains how to deploy them for gas–solid contact. Unfortunately, the direct use of MOFs as nanocrystals would lead to serious problems and risks. Here, for the first time, we report a novel MOF-based hybrid sorbent that is produced via an innovative in-situ microencapsulated synthesis. Using a custom-made double capillary microfluidic assembly, double emulsions of the MOF precursor solutions and UV-curable silicone shell fluid are produced. Subsequently, HKUST-1 MOF is successfully synthesized within the droplets enclosed in the gas permeable microcapsules. The developed MOF-bearing microcapsules uniquely allow the deployment of functional nanocrystals without the challenge of handling ultrafine particles, and further, can selectively reject undesired compounds to protect encapsulated MOFs.

An elasto-plastic constitutive model for rockfill materials considering particle breakage is proposed. Although numerous constitutive models have been proposed for rockfill materials, most of them are mainly based on empirical results, without consideration of the physical meaning of their parameters. In the present work, a yield function is derived based on the evolution of microstructures formed by rockfill particles. The dilatancy equation is derived based on both the theory of breakage mechanics and the energy dissipation equations. The breakage-induced hardening is also formulated to account for both the volumetric and shearing hardening of rockfill materials. It is demonstrated that, without compromising the simplicity of the model, most of the parameters in the proposed constitutive model have concrete physical meanings. Comparison of the model simulation with experimental data shows that the proposed model can describe reasonably the static loading characteristics of rockfill materials within a wide range of confining stresses.

The capillary barrier effect (CBE) is employed in a large number of geotechnical applications to decrease deep percolation or increase slope stability. However, the micro-scale behaviour of CBE is rarely investigated, and thus hampers the scientific design of capillary barrier systems. This study uses microfluidics to explore the micro-scale behaviour of CBE. Capillarity-driven water flow processes from fine to coarse porous media with different pore topologies and sizes were performed and analysed. The experimental results demonstrate that the basic physics of CBE is the preferential water movement into the fine porous media due to the larger capillarity. The effects of CBE on water flow processes can be identified as delaying the occurrence of breakthrough into the coarse porous media and increasing the water storage of the fine porous media. The CBE can impede the increase of the normalised length and decrease the normalised width of the water front, suggesting that the two normalised parameters are potential indicators to assess the performance of CBE at the micro scale. CBE can be formed in square and honeycomb networks with the ratio of coarse to fine pore throat width larger than 2·0 when gravity is neglected, and its performance can be affected by pore topology and size.

Although zeolitic imidazolate frameworks (ZIFs) have bright prospects in wide fields like gas storage/separation, catalysis and medicine, etc., their large-scale applications are bottlenecked by the absence of their low-cost commercial production technique. Here, we report an unconventional method suitable for environmentally friendly and low-cost mass-production of ZIFs. In this method, taking the synthesis of ZIF-8 as an example, ZnO was used instead of Zn(NO3)2 in traditional solvent synthesis methods and CO2 was introduced to dissolve ZnO in aqueous solution of 2-methylimidazole (HMeim) and form water soluble salt ([ZnMeim]+[MeimCOO]-) at room temperature. Then, by removing CO2 through heating or vacuuming, Meim-ions are produced and instantaneously assemble with [ZnMeim]+s to generate ZIF-8 without any by-product. Due to the absence of strong acid anions (such as NO3− and Cl− et al.) in solution, the washing of filter cake required in the conventional approaches could be omitted and the filtrate containing only water and HMeim could be reused completely. This method is really green as no waste gas or liquid generates because CO2 and water could be recycled perfectly. It overcomes almost all bottlenecks occurred in commercial production of ZIF-8 when using traditional methods. A pilot plant was established for mass-production of ZIF-8 and hundreds kilograms of ZIF-8 was produced, which indicates that the new method is not only environmentally friendly but also low cost and commercial accessibility. It is expected that the new method would open an avenue for commercial applications of ZIFs.

The design of efficient and robust non-precious metal electrocatalysts towards oxygen evolution reaction (OER) is of great value for developing green energy technologies. The in-situ formed high-valence (oxy)hydroxides species during the reconstruction process of pre-catalysts are recognized as the real contributing sites for OER. However, pre-catalysts generally undergo a slow and inadequate self-reconstruction. Herein, we reported a PO43− optimized CoFe-based OER catalysts with amorphous structure, which enables a fast and deep reconstruction during the OER process. The amorphous structure induced by ligands PO43− is prone to evolution and further form active species for OER. The electron interaction between metal sites can be modulated by electron-rich PO43−, which promotes generation of high active CoOOH. Simultaneously, the etching of PO43− from the pre-catalysts during the catalytic process is in favor of accelerating the self-reconstruction. As a result, as-prepared pre-catalyst can generate high active CoOOH at a low potential of 1.4 V and achieve an in-depth reconstructed nanosheet structure with abundant OER active sites. Our work provides a promising design of pre-catalysts for realizing efficient catalysis of water oxidation.

Various strategies, including controls of morphology, oxidation state, defect, and doping, have been developed to improve the performance of Cu-based catalysts for CO2 reduction reaction (CO2RR), generating a large amount of data. However, a unified understanding of underlying mechanism for further optimization is still lacking. In this work, combining first-principles calculations and machine learning (ML) techniques, we elucidate critical factors influencing the catalytic properties, taking Cu-based single atom alloys (SAAs) as examples. Our method relies on high-throughput calculations of 2669 CO adsorption configurations on 43 types of Cu-based SAAs with various surfaces. Extensive ML analyses reveal that low generalized coordination numbers and valence electron number are key features to determine catalytic performance. Applying our ML model with cross-group learning scheme, we demonstrate the model generalizes well between Cu-based SAAs with different alloying elements. Further, electronic structure calculations suggest surface - negative center could enhance CO adsorption by back donating electrons to antibonding orbitals of CO. Finally, several SAAs, including PCu, AgCu, GaCu, ZnCu, SnCu, GeCu, InCu, and SiCu, are identified as promising CO2RR catalysts. Our work provides a paradigm for the rational design and fast screening of SAAs for various electrocatalytic reactions.

Water electrolysis is a promising technology to produce hydrogen but it was severely restricted by the slow oxygen evolution reaction (OER). Herein, we firstly reported an advanced electrocatalyst of MOF-derived hollow Zn–Co–Ni sulfides (ZnS@Co9S8@Ni3S2-1/2, abbreviated as ZCNS-1/2) nanosword arrays (NSAs) with remarkable hydrogen evolution reaction (HER), OER and corresponding water electrolysis performance. To reach a current density of 10 mA cm−2, the cell voltage of assembled ZCNS-1/2//ZCNS-1/2 for urea electrolysis (1.314 V) is 208 mV lower than that for water electrolysis (1.522 V) and stably catalyzed for over 15 h, substantially outperforming the most reported water and urea electrolysis electrocatalysts. Density functional theory calculations and experimental result clearly reveal that the properties of large electrochemical active surface area (ECSA) caused by hollow NSAs and fast charge transfer resulted from the Co9S8@Ni3S2 heterostructure endow the ZCNS-1/2 electrode with an enhanced electrocatalytic performance.

In the US, there are over 130 million people living with Type 2 diabetes (T2D), who suffer from impaired regulation of hepatic glucose production, which eventually leads to β-cell failure. While insulin treatments are often recommended, they are burdensome to appropriately dose and can lead to dangerous hypoglycemic events. In contrast, glucagon- like peptide-1 receptor agonists (GLP-1 RAs), which mimic an incretin hormone secreted following carbohydrate intake, stimulate insulin and block glucagon secretion in a glucose- dependent manner, thereby eliminating the risk of hypoglycemia. These treatments lower endogenous glucose production and drive expansion of insulin-secreting β-cells to restore the native ability of patients to regulate glycemia. Unfortunately, current GLP-1 RAs must be injected either daily (Liraglutide) or weekly (Semaglutide), which results in significant patient burden and poor patient compliance. An ideal GLP-1 RA drug would provide continuous therapy for upwards of four months from a single administration during each primary care visit, which is the frequency which T2D patients visit their physician. In this work, we leverage an injectable hydrogel depot technology to develop a long-acting GLP- 1 RA drug. We show that a single injection of hydrogel-based therapies prolongs GLP-1 RA exposure and significantly improves management of blood glucose and weight in a rat model of T2D when compared with daily injections of a leading drug molecule over 42 days. Overall, we anticipate this work demonstrates the potential of a GLP-1 RA depot to dramatically reduce the frequency of therapeutic interventions, significantly increasing patient quality of life.

Chemical analysis of complex sample matrix is significant towards the efficient monitoring of human and environmental health. In the area of environmental contamination control and disease diagnosis, traditional analytical approaches rely on the separation effects by chromatography, such as gas chromatography (GC) and liquid chromatography (LC). Although GC/LC coupled with various detectors are extensively employed in analytical settings as the mature technologies, the disadvantages are also obvious, including the dependence on large and bulky instruments, complex and time-consuming instrumental operation, inevitable sample pretreatment and high cost. These disadvantages greatly limit their application in rapid diagnosis of disease, on-site samples testing, and household preclinic diagnosis. Immunosensing approaches, however, are promising substitutes applicable to the above scenarios. Featured with extraordinary selectivity and accuracy of detection attributed to the specific antibody-antigen recognition, immunoassays (IAs) have attracted extensive interests in recent years. Nevertheless, the major challenges are to overcome the inherent defects of IAs, such as low sensitivity of detection and difficult to realize multi-target simultaneous detection, in the meantime, to develop high-performance portable detection platforms. In this dissertation, advanced immunosensing platforms based on the principle of enzyme-linked immunosorbent assay (ELISA) and lateral flow immunoassay (LFIA) were systematically explored from the aspects of biorecognition, signal amplification, and signal quantification. Advanced functional nanomaterials, including metal-organic framework (MOF), graphene, carbon dot, mesoporous nanocomposite, etc., with unique physical or chemical properties were synthesized and employed as signal reporters in IAs for amplified sensitivity of detection. In addition, we designed and manufactured immunosensing platforms using 3D printing to achieve optimal integration of immunoassays, nanomaterials, and quantitative detection methods, thus the on-site, point-of-care, high-performance sample assessment was realized. Further, the extraordinary analytical performances of the immunosensing platforms were validated in practical applications for the detection of woodsmoke biomarkers in various human biofluids representing the exposure of human to contaminated air from wildfires, as well as the detection of environmental pesticide contaminants and the corresponding human metabolites in biofluids.

When providing care, to protect a part of the human body against resins and plas ters for certain time, it is necessary to use a circular knitted band in cotton as a raw material. The generating of Cotton fiber fly throughout the knitting process is due to interactions of frictional surfaces with the hairiness of ring spun yarn. During the manufacture short fibers are formed in the machine device, this problem is more important with the use of cotton yarns. In this research paper, the short fibers formation on circular knitting machines from spun yarns such as cotton is investigated The knitting conditions consist of; yarn tension, yarn feeding speed and the angle contact of the yarn with guides and needles. The results obtained illustrate the effect of yarn tension on the short fibers deposit caused by the combination of yarn friction with the knitting elements.

Proses dehidrasi merupakan salah satu proses yang sering dijumpai pada pabrik pengolahan gas alam. TEG (triethylene glycol) merupakan senyawa Glycol yang biasa digunakan pada proses dehidrasi gas alam. TEG dimanfaatkan sebagai absorben pada absorpsi air yang masih terkandung dalam gas alam yang bisa menyebabkan hydrate dan korosi. Proses absorpsi ini dilakukan di TEG contactor, TEG yang sudah digunakan akan dilakukan regenerasi, jika sudah di regenerasi maka TEG akan digunakan kembali. Tujuan dari penelitian ini yaitu melakukan proses estimasi temperatur yang sesuai untuk proses absorpsi unit regenerasi TEG, karena banyak TEG loss pada proses ini. TEG loss terjadi di TEG regenerator dan biasanya disebabkan oleh temperatur kondensor refluks yang kurang tepat sehingga menyebabkan TEG teruapkan keluar ke atmosfer bersama uap air. Kehilangan TEG adalah masalah bagi operasi yang penting dalam sistem dehidrasi. Langkah yang digunakan untuk mengurangi TEG loss adalah dengan melakukan estimasi temperatur dari condensor refluks dibuat menjadi 100°C dengan cara mengubah temperatur reboiler dari 190°C menjadi 197,3°C.

Biodegradable polymer berbahan dasar pati merupakan alternatif polymer ramah lingkungan yang dikembangkan untuk mengatasi permasalahan yang ditimbulkan oleh bahan – bahan polymer sekali pakai berbahan dasar minyak bumi . Biodegradable polymer dengan bahan dasar pati memiliki kelemahan antara lain nilai water vapor permeability dan water absorption nya yang besar serta nilai kuat tarik nya yang kecil. Kajian literatur ini bertujuan untuk mengetahui pengaruh filler dan coating beeswax terhadap karakteristik biodegradable polymer berdasarkan penelitian yang sudah dilakukan. Berdasarkan jurnal yang didapat pengaplikasian coating beeswax dapat menurunkan nilai water absorption lebih baik dari biodegradable polymer tanpa coating . Penelitian dengan menggunakan filler tanpa coating beeswax menghasilkan nilai water absorption sebesar 15,77% dengan bahan baku pati singkong. Penelitian menggunakan coating beeswax menghasilkan nilai water absorption sebesar 0,8%. Penelitian dengan coating beeswax menghasilkan nilai water vapor permeability sebesar 4,4042 x 10 -9 g mm/s m 2 Pa. Pada pengujian kuat tarik dengan menggunakan filler tanpa coating beeswax menghasilkan nilai kuat tarik sebesar 20 MPa. Penelitian menggunakan coating beeswax menghasilkan nilai kuat tarik terbaik yaitu 14 MPa.

This article deals with the numerical simulation of a two-dimensional instantaneous heat and mass transfer processes within a commonly used intermetallic compound (a.k.a. Mischmetal) packed in a unit disc of an annulus-disc reactors, during hydrogen gas desorption. Using the finite volumes technique bundled in the OpenFOAM® CFD code, temperature and amount of desorbed hydrogen and their time-averaged quantities inside the metal-hydride packed bed are obtained for various temperatures of fluids used in heat transfer, and several outlet pressure magnitudes. Using a set of numerical simulations, we have emphasized the impacts of both parameters on metal-hydride reactor performance related to discharging time. An excellent accord was recorded for the present simulations results compared against the literature-reported experimental data [20].

Galvanisasi merupakan proses pelapisan dengan seng ( Zinc ), dengan caara mencelupkan logam yang akan dilapisi kedalam media pelapis zinc yang sebelumnya telah mengalami proses peleburan, dimana titik lebur logam pelapis harus lebih rendah dari logam yang akan dilapisi. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh waktu pencelupan dan temperatur terhadap proses pencelupan. Analisis yang akan dilakukan adalah uji ketebalan permukaan dan melakukan uji kekerasan bahan setelah dilakukan pencelupan. Dalam penelitian ini material yang digunakan adalah baja dengan tipe UNP, Sebelum dilakukan Hot Dip Galvanized perlu dilakukan pretreatment menggunakan bahan kimia, yaitu proses degreasing, water rinsing, pickling, fluxing, drying . Setelah itu dilakukan tahap Galvanisasi, Variabel yang akan digunakan adalah suhu zinc bath 440 o C,445 o C,450 o C dan waktu pencelupan 2,4,6,8,10 menit. Dari hasil analisis semakin lama waktu pencelupan pada proses hot dip galvanizing mengakibatkan semakin tebal lapisan zinc yang dihasilkan dan Semakin tinggi temperatur zinc saat proses hot dip galvanizing juga mengakibatkan semakin tebal lapisan zinc yang di hasilkan, di karenakan kekentalan dari zinc menurun.

Film cooling is used to protect turbine components from the extreme temperatures by ejecting coolant through arrays of holes to create an air buffer from the hot combustion gases. Limitations in traditional machining meant film cooling holes universally have sharp inlets which create separation regions at the hole entrance. The present study uses experimental and computational data to show that these inlet separation are a major cause of performance variation in crossflow fed film cooling holes. Three hole designs were experimentally tested by independently varying the coolant velocity ratio (VR) and the coolant channel velocitty ratio (VRc) to isolate the effects of crossflow on hole performance. Leveraging additive manufacturing technologies, the addition of a 0.25D radius fillet to the inlet of a 7-7-7 shaped hole is shown to significantly improve diffuser usage and significantly reduce variation in performance with VRc. A second AM design used a very large radius of curvature inlet to reduce biasing caused by the inlet crossflow. Experiments showed that this “swept” hole design did minimize biasing of coolant flow to one side of the shaped hole and it significantly reduced variations due to varying VRc. RANS simulations at six VR and three VRc conditions were made for each geometry to better understand how the new geometries changed the velocity field within the hole. The sharp and rounded inlets were seen to have very similar tangential velocity fields and jet biasing. Both AM inlets created more uniform, slower velocity fields entering the diffuser. The results of this paper indicate large improvements in film cooling performance can be found by leveraging AM technology.

The influence of metakaolin (MK) addition on the mechanical and hydration performance of ultra-high-performance (UHP) paste was investigated. UHP mortars were prepared to evaluate the compressive strength when MK was used as a cement replacement at levels of 0, 5, 10, 15 and 20%. The hydration heat evolutions of pastes blended with MK were examined. The chemically bound water and MK reaction degree were determined to assess the hydration reaction degrees of the pastes. Differential thermal analysis, X-ray diffraction, mercury intrusion porosimetry and scanning electron microscopy were carried out to investigate the phase composition and microstructure of pastes. The results showed that the mechanical performance of UHP mortar at an early age is improved by the addition of MK due to its filling effect and pozzolanic reaction. The reaction rate of MK in the pastes significantly decreased at a later age and at a low water-to-binder ratio, but the incorporation of MK still had an improving effect on the mechanical strength of UHP mortars at a later age. The incorporation of MK reduced the content of calcium hydroxide crystals and increased the content of calcium silicate hydrate and calcium aluminium silicate hydrate phases in the pastes. The hardened MK-dosed paste samples showed improved microstructure with lower porosity and a refined pore structure.

The ‘rope effect’ is a positive effect caused by the failure of fasteners of dowel-type connections. A similar mechanism can be found in connections with screw reinforcement. For self-tapping screws used as reinforcement for connections, bending of the self-tapping screws tends to close developed cracks. Utilising the withdrawal resistance provided by the threads on the pointed end of the screw and the pull-through resistance from the screw head, screw reinforcement enhances the embedment strength and splitting resistance of the wood and increases the ductility of the connection. The influence of different thread lengths and locations on reinforcement effectiveness regarding the embedment strength of the timber was investigated in this study. For cases with threads located only on the pointed end, the splitting resistance increased with longer thread length, indicating that the rope effect was progressively enhanced. It was also found that screws with halved thread length demonstrated similar reinforcement effectiveness to fully threaded screws while the partial threads reduced the risk of damaging the screw during installation. A calculation method to predict the load-carrying capacity of screw-reinforced dowel-type connections was also formulated.

There are many photovoltaic (PV) applications where lighter weight and/or bendable PV power would be beneficial. This includes the curved surfaces of buildings, buildings with weight limitations, boats, automobiles, or other portable applications. In many of these cases, the bending will be only a single occurrence at installation or the amount of bending, even if repeated, is not dramatic. This allows for crystalline silicon modules to be used. For flexible applications, the dominant material for the frontsheet is polyethylene tetrafluoroethylene (PETFE). As a fluoropolymer it resists soiling, is UV stable, and PETFE is a more mechanically durable fluoropolymer. However, in the interests of keeping costs down, less expensive alternative polymers are desirable. In this study, highly accelerated ultraviolet light and heat stresses are applied to candidate materials and the degradation kinetics are determined to provide information to evaluate their suitability for use in a PV application.

Soils containing organic matter exhibit low shear strength and high compressibility. Lime stabilisation has been shown to improve the engineering properties of clayey soils. An attempt was made to study the effect of organic matter (starch and peat) on the shear strength of lime-stabilised clayey soils subjected to longer curing periods (up to 180 days). Most studies have reported the strength behaviour of lime-stabilised organic soils up to 60 days. Vane shear tests were carried out on artificially prepared organic soil mixtures treated with 6% lime after different curing periods (0, 7, 30, 60, 90 and 180 days). The results indicate that the improving effect of lime is deteriorated in the presence of organic matter as the curing period increases. It was observed that, for lime-stabilised clayey soils containing organic matter, the strength seemed to increase up to 30 days, after which it ceased. The strength reduction in lime-stabilised clayey soils containing organic matter depended on the pH and functional groups present in the soil. Fourier transform infrared spectroscopy of cured samples was also carried out to examine the microstructural changes responsible for the strength change in lime-stabilised clayey soils.

Desiccation cracking in clay soils is a combined mechanical and hydraulic problem and such soils can be improved by various methods including reinforcement with fibres. The relationships between tensile strength, cracking resistance and water-retention properties of fibre-reinforced fine-grained soils lack coverage in the literature to date. In this study, these three properties are evaluated and connected by way of a series of tensile strength and desiccation cracking tests on fibre-reinforced London clay. The results confirm that increased fibre addition delays the occurrence of peak stress and changes failure behaviour from brittle to ductile. The tensile strength increment gets higher as water content decreases, and reaches a maximum value of 460 kPa when the water content is 12%. The crack intensity factor reduces from 7.20% to 0.89% when 12 mm long fibre is used at a ratio of 0.9%. Fibre reinforcement also changes the crack development pattern by reducing the size of large cracks and increasing the proportion of small individual cracks. However, the presence of fibres was not observed to change the water-retention properties of the soil, indicating that the tensile improvement comes from the pull-out resistance of the fibres rather than suction changes.

Summary Background Earlier studies have shown that nasalization affects the radiated spectrum by modifying the vocal tract transfer function in a complex manner. Methods Here we study this phenomenon by measuring sine-sweep response of 3-D models of the vowels /u, a, ᴂ, i/, derived from volumetric MR imaging, coupled by means of tubes of different lengths and diameters to a 3-D model of a nasal tract. Results The coupling introduced a dip into the vocal tract transfer function. The dip frequency was close to the main resonance of the nasal tract, a result in agreement with the Fujimura & Lindqvist in vivo sweep tone measurements [Fujimura & Lindqvist, 1972]. With increasing size of the coupling tube the depth of the dip increased and the first formant peak either changed in frequency or was split by the dip. Only marginal effects were observed of the paranasal sinuses. For certain coupling tube sizes, the spectrum balance was changed, boosting the formant peaks in the 2 – 4 kHz range. Conclusion A velopharyngeal opening introduces a dip in the transfer function at the main resonance of the nasal tract. Its depth increases with the area of the opening and its frequency rises in some vowels.

Statement of problem The crystallization process of lithium disilicate crowns has been reported to cause dimensional change, but whether the fit of chairside computer-aided design and computer-aided manufactured (CAD-CAM) zirconia-reinforced lithium silicate crowns is affected is unclear. Purpose The purpose of this in vitro study was to evaluate with a 3-dimensional superimposition analysis technique the marginal and internal adaptation of fully crystallized versus partially crystallized zirconia-reinforced lithium silicate ceramic CAD-CAM fabricated crowns. Additionally, the silicone replica technique and direct viewing of marginal gap values were compared with the 3-dimensional superimposition analysis technique. Material and methods The marginal and internal adaptation of a fully crystallized zirconia-reinforced lithium silicate (CELTRA DUO) were compared with those of a partially crystallized zirconia-reinforced lithium silicate (VITA SUPRINITY) after crystallization. Sixteen crowns (n=8) were fabricated with a chairside CAD-CAM system. The crowns and die and crown assembly were scanned with an optical scanner for the 3-dimensional superimposition analysis. Four hundred sixty-eight measurements were made for each crown, 78 in each 2-dimensional section. Marginal discrepancy was measured by using the direct viewing technique. The internal adaptation of the shoulder area, axial space, and occlusal space was measured by using the silicone replica technique. Both gap values were compared with the 3-dimensional superimposition analysis results by using the independent t test. The 2-way ANOVA was used to detect the effect of each variable (group and site) (α=.05). Results The VITA SUPRINITY crowns showed statistically higher marginal discrepancy values than the CELTRA DUO crowns in both 3-dimensional superimposition analysis and the direct viewing method, and the lingual aspect recorded the highest marginal discrepancy mean value when compared with other aspects. The 3-dimensional superimposition analysis and the direct viewing method were statistically similar (P=.076). The VITA SUPRINTY crowns showed higher internal gap mean values than the CELTRA DUO crowns in both 3-dimensional superimposition analysis and silicone replica techniques. The occlusal space recorded the highest mean value in both groups. Assessment by 3-dimensional superimposition analysis and silicone replica techniques showed statistical difference in internal gap values (P=.04). Conclusions CELTRA DUO showed better precision fit values than VITA SUPRINITY. Three-dimensional superimposition analysis is a reliable method of evaluating marginal and internal adaptation.

The influence of direct incorporation of thermally efficient phase-change materials (PCMs) on the hydration and mineralogical properties of cement mortar was investigated. To assess the viability of bulk addition of PCMs to a cementitious system, tests of the early age, hydration, mechanical, durability and mineralogical properties were carried out. Organic PCMs showed an increase in setting time, while inorganic materials exhibited fast setting characteristics. Surface temperature was also found to be lower for cement paste with incremental dosages of PCM. However, chemical shrinkage was found to be reduced in the presence of PCM except for the inorganic type. It was observed from the results that PCMs negatively influenced the rate of strength development of a cementitious mortar. The slow rate of strength development was found to be attributed to interrupted hydration, which was confirmed through mineralogical studies. Further, from the thermo-gravimetric analysis, it was observed that the presence of PCMs in a cementitious system increased calcium hydroxide content and reduced the content of water related to hydration products.

The flexural performance of a spliced composite slim beam with a slotted web (SCSB-SW) was assessed and prediction formulae of flexural capacity and initial stiffness for the beam were deduced. Through a four-point bending test, the flexural performance of the SCSB-SW was preliminary studied. The experimental results indicated that the section of the SCSB-SW conformed to the plane section assumption in the elastic stage. The beam failed in a ductile failure mode while there was no obvious relative slip between the steel beam and concrete slab in the failure stage. Finite-element models were developed and validated using the test results. A parametric analysis revealed that even if the cross-sectional dimensions and the position of the neutral axis in the beam are changed, the results predicted by the formulae still matched the numerical results well. The material strength, the thickness of the bottom flange of the steel beam and the concrete slab dimensions were found to play key roles in the flexural capacity of the beam, whereas the compressive strength grade of the concrete, the depth of the steel beam web and the dimensions of the concrete flange have significant effects on the initial stiffness of the beam.

The movement of water in concrete structures and buildings is a fundamental subject and therefore it is necessary to understand the mechanisms and processes involved. This paper presents a method to estimate the moisture diffusivity of concrete using gravimetric measurements, together with discretised electrical resistivity measurements. To improve the repeatability of the method, various concrete mixes with and without supplementary cementitious materials were tested. The samples were conditioned under two regimes representing poor and good curing; the samples were then exposed to a simulated hot environment with a diurnal temperature fluctuation of 20–40°C and 60% ambient relative humidity. The basis of the method was to measure the amount of water absorbed by the concrete sample at different depths as a function of time and then Boltzmann's transformation was used to analyse the experimental results obtained. Once a master curve using the Boltzmann transformation is formed, the moisture diffusivity can be obtained. The results showed that the relationship between moisture diffusivity and moisture content can be described by an exponential function.

The selection of parameters affects the surface roughness in the additive manufacturing process. This study aims to determine the optimal combination of input parameters for predicting and minimising the surface roughness of samples produced by Fused Deposition Modelling on a 3D printer using a cascade-forward neural network (CFNN) and genetic algorithm. Box–Behnken Design with four independent printing parameters at three levels is used, and 25 parts are fabricated with a 3D printer. Roughness tests are performed on the fabricated parts. Models generated by the hybrid algorithm achieve the best results for predicting and optimising surface roughness in 3D-printed parts. The surface roughness prediction accuracy of the trained CFNN with optimised parameters is more accurate compared to previous random test results.

Power components such as High Electron Mobility Transistors (HEMTs) are used for high power and high frequency applications. These tend to overheat and destroy their packaging and connections to the wire bondings. This paper presents planar micro-thermoelectric sensors (μTESs) developed to measure partial heat flow dissipated by the HEMTs to avoid the HEMTs from reaching critical temperatures. These sensors use the same active materials as well as the same fabrication process as the HEMTs, enabling them to be fabricated simultaneously for a simple integration. The HEMTs’ active layers consist in AlGaN/GaN heterostructures resulting in the formation of a 2D Electron Gas (2DEG) at the interface. Tension factors of 47 mV/(K.mm2) were obtained with these sensors and heat flows of 0.2 W to 7 W were measured.

Resumen Se produjeron ladrillos de arcilla obtenidos con mezcla de arcilla con residuos de un horno eléctrico en desuso y reforzados con fibras cerámicas para la obtención de un material cerámico con características refractarias. Las mezclas de arcilla/partículas recicladas fueron 50:50 en peso, y la incorporación de fibra fue en un 10 y un 20 % en volumen, para obtener un cerámico por sinterización a 1.000 °C durante 2 h. Los materiales diseñados fueron caracterizados por difracción de rayos X, se determinó la resistencia a compresión, flexión, densidad, porosidad y absorción. También se comprobó su desempeño térmico por exposición directa a llama 1.000 °C. Los resultados mostraron que en la medida en que se incorpora fibra cerámica la resistencia a compresión disminuyó un 17,3 % para AF10 y un 17,0 % para AF20. Los valores de resistencia a flexión estuvieron en 3,4 MPa. El coeficiente de conductividad térmica fue de 0,5322 W/mK, y durante la exposición directa a la llama, las muestras lograron un gradiente térmico de -700 °C para muestras de 2 cm de espesor. Las fases mineralógicas obtenidas para los ladrillos fueron mullita, corindón y cordierita, las cuales se consideran refractarias. Abstract The aim of this research was the production of clay-brick, from red clay, waste from a disused electric furnace, reinforced with ceramic fibers, to obtain a ceramic material with refractory characteristics. The clay/waste particle proportion was 50:50 by weight, and the incorporation of fiber was 10% and 20% by volume, to obtain a ceramic by sintering at 1000°C, for 2 hours. The designed materials were characterized by X-ray diffraction, the flexural and compressive strength, density, porosity, and absorption were determined. The thermal performance was also verified by direct exposure to 1000°C flame. The results showed that as ceramic fiber was incorporated, the compressive strength decreased by 17.3% for AF10 and 17.0% for AF20. The flexural strength values were at 3.4 MPa. The coefficient of thermal conductivity was 0.5322 W/m.K, and, during direct flame exposure, the samples achieved a thermal gradient of ~ 700 °C for samples 2 cm thick. The mineralogical phases obtained for the bricks were mullite, corundum, and cordierite, which are considered refractory.

The presented study focuses on a numerical simulation of the transport phenomena inside a solid oxide fuel cell anode. The classical mathematical model leads to a notable discrepancy between measured and predicted overpotentials. One of the possible reasons is the assumption of the constant values of electrochemical reaction charge transfer coefficients. A modified formulation of the problem includes data-driven correction of reaction charge transfer coefficients in the electrochemical reaction model. Here we show a dedicated computational scheme in which an artificial neural network updates the charge transfer coefficients depending on the operational conditions and the available datasets. The neural network was trained on twelve experimental data points of an anode's polarization curve obtained from the literature. The training set contained data for the anode operating in two different temperatures - 800 °C and 900 °C. The test set contained additional six data points for an anode operating at 1000 °C. Charge transfer coefficients were proposed by the Artificial Neural Network as a functional relation of the temperature and withdrawn current. The results of the predictions are juxtaposed with the experimental data from the literature. It was shown that an Artificial Neural Network could improve an electrochemical reaction model in Solid Oxide Fuel Cell modeling.

The electrochemical performance of solid oxide cells (SOCs) is investigated under both fuel cell and electrolyzer operations to understand their asymmetric behavior between the two operation modes. The current–voltage and electrochemical impedance characteristics of a hydrogen-electrode-supported cell are experimentally analyzed. Also, a numerical model is developed to reproduce the cell performance and to understand the internal resistances of the cell. Partial pressures of supplied gas and load current are varied to evaluate their effects on the cell performance. The gas partial pressures of hydrogen and steam supplied to the hydrogen electrode are kept equivalent so that the cell performance can be fairly compared between the two operation modes when the same current is applied. It is found that the origin of the asymmetry is mostly from the hydrogen electrode; both activation and concentration overpotentials show asymmetric behavior particularly at high current densities. A numerical experiment is also conducted by deliberately changing parameters in the model. Asymmetry in the activation overpotential is found to be originated from the non-identical charge-transfer coefficients in the Butler–Volmer equation and also from the non-uniform gas concentration formed in the hydrogen electrode under current-biased conditions. On the other hand, asymmetry in the concentration overpotential is associated with the non-equimolar counter diffusion of hydrogen and steam caused by the effect of Knudsen diffusion. Therefore, enhancing gas transport in the hydrogen electrode and reducing the contribution of Knudsen diffusion are effective approaches to reduce asymmetry not only in the concentration overpotential but also in the activation overpotential.

New-type magnesium alloy with prominent solubility and mechanical property lays foundation for preparing fracturing part in petroleum extraction. Herein, Mg-xZn-Zr-SiC alloy is prepared with casting strategy. Electrochemical and compression tests are conducted to assess the feasibility as decomposable material. Morphology, composition, phase and distribution are characterized to investigate decomposition mechanism. Results indicate that floccule, substrate component and reticulate secondary phase are formed on as-prepared surface. Sample also acts out enhanced compression strength to maintain pressure and guarantee stability in dissolution process. Furthermore, as decomposition time and zinc content increase, couple corrosion intensifies, resulting in gradually enhanced decomposition rate. Rapid sample decomposition is mainly due to basal anode dissolution, micro particle exfoliation and poor decomposition resistance of corroding product. Such work shows profound significance in preparing new-type accessible alloy to ensure rapid dissolution of fracturing part and guarantee stable compression strength in oil-gas reservoir exploitation.

The properties of the combustion and deflagration to detonation transition (DDT) of Al/Fe2O3/RDX hybrid nanocomposites, a type of potentially novel lead-free primary explosives, were tested in weakly confined conditions, and the interaction of Al/Fe2O3 nanothermite and RDX in the DDT process was studied in detail. Results show that the amount of the Al/Fe2O3 nanothermite has a great effect on the DDT properties of Al/Fe2O3/RDX nanocomposites. The addition of Al/Fe2O3 nanothermite to RDX apparently improves the firing properties of RDX. A small amount of Al/Fe2O3 nanothermite greatly increases the initial combustion velocity of Al/Fe2O3/RDX nanocomposites, accelerating their DDT process. When the contents of Al/Fe2O3 nanothermite are less than 20 wt%, the DDT mechanisms of Al/Fe2O3/RDX nanocomposites follow the distinct abrupt mode, and are consistent with that of RDX, though their DDT processes are different. The RDX added into the Al/Fe2O3 nanothermite increases the latter's peak combustion velocity and makes it generate the DDT when the RDX content is at least 10 wt%. RDX plays a key role in the shock compressive combustion, the formation and the properties of the DDT in the flame propagation of nanocomposites. Compared with RDX, the fast DDT of Al/Fe2O3/RDX nanocomposites could be obtained by adjusting the chemical constituents of nanocomposites.

The loading strategy of cocatalysts affects its activity exerting and atom utilization. Here, a novel strategy for loading precious metal (Pt) cocatalysts by means of ultrathin N-doped carbon layer is reported. The strategy is based on a pyrolysis process of predesigned N-containing polymers and Pt complexes on hard-template surface, during which Pt can be reduced by carbon from pyrolysis at high temperatures. Finally, the hollow TiO2 composite with stable and dispersed Pt on its inner surface was prepared. It shows an ultrahigh photocatalytic H2 production activity as high as 25.7 mmol h−1 g−1 with methanol as sacrificial regent, and displays an apparent quantum yield as 13.2%. The improved photocatalytic activity and stability can be attributed to the highly dispersed and ultrafine Pt nanoparticles, enhanced interaction between Pt-species and carbon support, fast photo-excited electron transport from the high graphitization degree of NC layers, ample oxygen vacancies/defects, as well as the manipulated local charge distribution of Pt/NC-layer configuration. Additionally, the universality of the proposed strategy was demonstrated by replacing metal sources (such as, Ru and Pd). This work presented a promising strategy for the design and development of novel photocatalysts, which shows a broad application prospect.

We report a new facile light-induced strategy to disperse micron-sized aggregated bulk covalent organic frameworks (COFs) into isolated COFs nanoparticles. This was achieved by a series of metal-coordinated COFs, namely COF-909-Cu, -Co or -Fe, where for the first time the diffusio-phoretic propulsion was utilized to design COF-based micro/nanomotors. The mechanism studies revealed that the metal ions decorated in the COF-909 backbone could promote the separation of electron and holes and trigger the production of sufficient ionic and reactive oxygen species under visible light irradiation. In this way, strong light-induced self-diffusiophoretic effect is achieved, resulting in good dispersion of COFs. Among them, COF-909-Fe showed the highest dispersion performance, along with a drastic decrease in particle size from 5 μm to 500 nm, within only 30 min light irradiation, which is inaccessible by using traditional magnetic stirring or ultrasonication methods. More importantly, benefiting from the outstanding dispersion efficiency, COF-909-Fe micro/nanomotors were demonstrated to be efficient in photocatalytic degradation of tetracycline, about 8 times faster than using traditional magnetic stirring method. This work opens up a new avenue to prepare isolated nanosized COFs in a high-fast, simple, and green manner.

Electrochemical CO2 reduction (CO2RR) over molecular catalysts is a paramount approach for CO2 conversion to CO. Herein, we report a novel phthalocyanine-derived catalyst synthesized by a two-step method with a much improved electroconductivity. Furthermore, the catalyst contains both Ni–N4 sites and highly dispersed metallic Ni nanoclusters, leading to an increased CO2RR currents by two folds. Isotope labelling study and in situ spectroscopic analysis demonstrate that the existence of metallic Ni nanoclusters is the key factor for the activity enhancement and can shift the CO2RR mechanism from being electron transfer (ET)-limited (forming ∗COO−) to concerted proton-electron transfer (CPET)-limited (forming CO).

This paper presents the results of both experimental and numerical investigations on the overall structural performance of two-equal-span reinforced concrete perforated (castellated) beams subjected to external pre-stressing. First, the effects of providing castellated openings along with the application of external pre-stressing on both the ultimate capacity and the percentage of moment redistribution were investigated experimentally. Then, after validation of the numerical modelling, the effects of controlling the parameters on the percentage of moment redistribution were investigated numerically. Experimental results showed that providing castellated openings accelerated the appearance of both flexural and shear cracks, and decreased the ultimate capacity by about 24% compared to that of a solid beam. Moreover, application of external pre-stressing on the castellated beam compensated for the reduction in ultimate capacity and outperformed it by about 9% compared to that of a solid beam. Based on the numerical results, it appears to be better to increase the amount of main tensile steel and strand eccentricity at the hogging moment zone, as well as increase the effective pre-stressing force, to reduce the percentage of moment redistribution at both sagging and hogging moments.

Direct conversion of syngas to aromatics (STA) over oxide-zeolite composite catalysts is promising as an alternative method for aromatics production. However, the structural effect of the oxide component in composite catalysts is still ambiguous. Herein, we investigate the size effect by selecting ZnCr2O4 spinel, as a probe oxide, mixing with H-ZSM-5 zeolite as a composite catalyst for STA reaction. The CO conversion, aromatics selectivity and space-time yield (STY) of aromatics are all significantly improved with the crystal size of ZnCr2O4 oxide decreases, which can mainly attribute to the higher oxygen vacancy concentration and thus the rapid generation of more C1 oxygenated intermediate species. Based on the understanding of the size–performance relationship, ZnCr2O4-400 with a smaller size mixing with H-ZSM-5 can achieve 32.6% CO conversion with 76% aromatics selectivity. The STY of aromatics reaches as high as 4.79 mmol gcat−1 h−1, which outperforms the previously reported some typical catalysts. This study elucidates the importance of regulating the size of oxide to design more efficient oxide-zeolite composite catalysts for conversion of syngas to value-added chemicals.

Radiative cooling without energy consumption and environmental pollution holds great promise as the next-generation cooling technology. To date, daytime radiative cooling performance is still slightly low, especially in humid areas. In this work, we demonstrated that nanoporous polyethylene (Nano PE) film can improve solar reflectivity from 96% to 99%, thus boosting radiative cooling performance. Moreover, the experimental results in humid areas indicate that Nano PE films can improve radiative cooling performance by ∼76% in a clear day and 120% in a day with few clouds. Additionally, compared with ordinary PE films, thin Nano PE films have significantly higher weather fastness and mechanical strength. More importantly, nano PE films can scatter part of visible light, thus suppressing the generation of light pollution in practical applications. Lastly, the modeling results reveal that with Nano PE films, more than 95% of China's areas can achieve daytime cooling performance. Our work can boost the development of radiative cooling technology with a very low cost.