Large Substrates Research Articles

Distinct epiphyte responses to drought in tropical mountain cloud forests

AbstractEpiphytes are often considered to be significantly impacted by precipitation changes because their lack of direct access to soil water. However, few in situ studies have examined how reduction in water availability may affect epiphyte growth. Using a unique stemflow collection and diversion device, we examined the effects of stemflow reduction of 25% and 50% on the growth and leaf traits of two common but distinct epiphyte species in a subtropical forest. One species (Asplenium nidus) has a large substrate, and another (Haplopteris zosterifolia) without known water storage structure. The 25% stemflow reduction had limited effects on the growth and leaf traits of the two epiphytes, indicating that 25% stemflow reduction did not reach the water stress threshold for the two epiphytes. It is also possible that the actual reduction in water availability was less than 25% since epiphytes do not use all available stemflow and there could be other sources of water such as fog and throughfall. The 50% stemflow reduction reduced leaf number and leaf area of H. zosterifolia, but not A. nidus, likely because water stored in the large substrate of A. nidus mitigated the impact of stemflow reduction. The thinner leaves, smaller leaf dry matter content, and lower δ13C of A. nidus than H. zosterifolia support the role of water storage of the substrate of A. nidus on mitigating water stress. The 50% stemflow reduction increased leaf thickness, leaf dry matter content of H. zosterifolia, and thickness of abaxial cuticle layer of both epiphytes but had no effect on δ13C. Stemflow reduction had no effects on nutrient concentration and nutrient ratios of both epiphytes suggesting that the epiphytes were able to maintain stoichiometry. Our results indicate that the epiphytes minimized nonstomatal water loss when environmental dryness increased but maintained stomata conductance, which could be important in minimizing the impacts of drought on plant growth and quickly resuming growth once drought ends. Our study highlights that not all epiphytes are similarly vulnerable to drought and precipitation reduction may change the relative abundance of epiphytes with and without water storage structure.

Annealing-Modulated Surface Reconstruction for Self-Assembly of High-Density Uniform InAs/GaAs Quantum Dots on Large Wafers Substrate.

In this work, we developed pre-grown annealing to form β2 reconstruction sites among β or α (2 × 4) reconstruction phase to promote nucleation for high-density, size/wafer-uniform, photoluminescence (PL)-optimal InAs quantum dot (QD) growth on a large GaAs wafer. Using this, the QD density reached 580 (860) μm-2 at a room-temperature (T) spectral FWHM of 34 (41) meV at the wafer center (and surrounding) (high-rate low-T growth). The smallest FWHM reached 23.6 (24.9) meV at a density of 190 (260) μm-2 (low-rate high-T). The mediate rate formed uniform QDs in the traditional β phase, at a density of 320 (400) μm-2 and a spectral FWHM of 28 (34) meV, while size-diverse QDs formed in β2 at a spectral FWHM of 92 (68) meV and a density of 370 (440) μm-2. From atomic-force-microscope QD height distribution and T-dependent PL spectroscopy, it is found that compared to the dense QDs grown in β phase (mediate rate, 320 μm-2) with the most large dots (240 μm-2), the dense QDs grown in β2 phase (580 μm-2) show many small dots with inter-dot coupling in favor of unsaturated filling and high injection to large dots for PL. The controllable annealing (T, duration) forms β2 or β2-mixed α or β phase in favor of a wafer-uniform dot island and the faster T change enables optimal T for QD growth.

Merging decatungstate photocatalysis and copper‐catalyzed azide‐alkyne cycloaddition reaction for the formation of 1,2,3‐triazoles in water†

Merging photoredox and catalysis by transition metals, coined as metallaphotoredox catalysis, proved to be an excellent new platform for the development of new synthetic strategies for the formation of carbon–carbon and carbon‐heteroatom bonds. Herein, we report a dual catalytic system that has been successfully developed for the azide‐alkyne ligation process to yield 1,4‐disubstituted‐1,2,3‐triazoles. It consists of merging the decatungstate anion [W10O32]4−‐photocatalyzed hydrogen atom transfer from ethanol as a source of hydrogen atom abstraction to produce the one‐electron‐reduced form H+[W10O32]5−, which reduces Cu(II) precursor into Cu(I) starting then the copper‐catalyzed azide‐alkyne cycloaddition reaction (CuAAC). The resulting bifunctional H+[W10O32]5−/Cu catalytic system operates efficiently in an environmentally benign water–ethanol solvent mixture as reaction medium, resulting in the regioselective formation of 1,4‐disubstituted‐1,2,3‐triazole derivatives, with high yields up to 99% and large substrate application scope under mild conditions. This dual catalytic approach has proven to function under sunlight exposition too with recovery and reuse of the catalytic system for several times.

Dynamic in situ growth of bonded-phase silica nanospheres on silica capillary inner walls for open-tubular liquid chromatography

Silica nanospheres (SNS) were grown on the inner walls of silica capillaries through a dynamic in situ nucleation process to prepare a highly porous and large accessible surface area substrate. The SNS were then functionalized with octadecyl (C18), 3-aminopropyltriethoxysilane (APTES), beta-cyclodextrin (β-CD), and amino groups to develop robust and efficient chromatographic stationary phases. The modified silica capillaries were exploited for open-tubular liquid chromatography (OT-LC) and open-tubular capillary electrochromatography (OT-CEC) applications. The prepared stationary phases were compared to conventional capillaries in terms of separation performance. The synthesis process was optimized, and the bonded-phase stationary phases were characterized by the electron microscopy technique. The effects of different solvents, additives, and functional groups on the geometry and chromatographic resolving power of the SNS were envisaged. The capillaries modified with octadecyl groups were evaluated for the separation of non-steroidal anti-inflammatory drugs, phenones, alkenylbenzenes, and enantiomers of chlorophenoxy herbicides. As an application instance, an SNS-C18-coated capillary was utilized for the separation of alkenylbenzenes from clove extract and protein digest medium, through OT-LC and OT-CEC techniques, respectively. The β-CD functionalized capillary was applied for the OT-CEC separation of a dichlorprop racemic mixture.Graphical abstract

Nitrogen-Enriched Biguanidine-Functionalized Cobalt Ferrite Nanoparticles as a Heterogeneous Base Catalyst for Knoevenagel Condensation under Solvent-Free Conditions.

Designing efficient, economical heterogeneous catalysts for the Knoevenagel condensation reaction is highly significant owing to the importance of reaction products in industries as well as pharmaceutics. Herein, we have designed and synthesized biguanidine-functionalized basic magnetically retrievable cobalt ferrite nanoparticles (CFNPs) for the synthesis of Knoevenagel condensation products using benzaldehydes and active methylene compounds (malononitrile/ethyl cyanoacetate/cyanoacetamide). Several advanced techniques, such as Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and vibration sample magnetometry (VSM), were utilized to precisely characterize the catalyst. The robust features of the current approach involve outstanding catalytic performance, solvent-free reaction conditions, ease of catalyst retrievability, easy workup procedure, large substrate tolerance, high turnover frequency (TOF) values (up to 486.88 h-1), values of green chemistry metrics such as E-factor (0.15), reaction mass efficiency (RME) value (87.07%), carbon efficiency (93.4%), and atom economy (AE) value (88.10%) close to their ideal values, and recyclability up to eight runs without a considerable reduction in activity, boosting the appeal of this approach from a commercial and ecological point of view.

Design of Heme Enzymes with a Tunable Substrate Binding Pocket Adjacent to an Open Metal Coordination Site.

The catalytic versatility of pentacoordinated iron is highlighted by the broad range of natural and engineered activities of heme enzymes such as cytochrome P450s, which position a porphyrin cofactor coordinating a central iron atom below an open substrate binding pocket. This catalytic prowess has inspired efforts to design de novo helical bundle scaffolds that bind porphyrin cofactors. However, such designs lack the large open substrate binding pocket of P450s, and hence, the range of chemical transformations accessible is limited. Here, with the goal of combining the advantages of the P450 catalytic site geometry with the almost unlimited customizability of de novo protein design, we design a high-affinity heme-binding protein, dnHEM1, with an axial histidine ligand, a vacant coordination site for generating reactive intermediates, and a tunable distal pocket for substrate binding. A 1.6 Å X-ray crystal structure of dnHEM1 reveals excellent agreement to the design model with key features programmed as intended. The incorporation of distal pocket substitutions converted dnHEM1 into a proficient peroxidase with a stable neutral ferryl intermediate. In parallel, dnHEM1 was redesigned to generate enantiocomplementary carbene transferases for styrene cyclopropanation (up to 93% isolated yield, 5000 turnovers, 97:3 e.r.) by reconfiguring the distal pocket to accommodate calculated transition state models. Our approach now enables the custom design of enzymes containing cofactors adjacent to binding pockets with an almost unlimited variety of shapes and functionalities.

Sub-500 nm patterned synthesis of corrosion resistant SnO2 and Pt@SnO2 using metal-organic precursor

In this study, a thin film of transparent conducting metal oxide, SnO2, is obtained using a novel metal-organic precursor, Sn-TOABr complex. The precursor is synthesized by phase-transferring tin from the aqueous layer to the liquid-liquid interface. The formed precursor is used for depositing SnO2 thin films over arbitrary and even large substrates via the modified atmospheric pressure chemical vapor deposition (MAPCVD) method in a simple furnace at 450 °C. The vapor-deposited SnO2 thin films are crystalline, semiconducting, highly transparent with excellent mechanical robustness against scratch and scotch tape tests, and resistant towards corrosive media. The obtained robust thin films via this MAPCVD technology expand applications towards protective coatings for arbitrary substrates. Using a simple direct micromolding technique, sub-500 nm patterns of SnO2 and Pt@SnO2 were obtained. This single-step soft lithography patterning technique, besides being cost-effective, offers a large throughput.

(Ph3P)AuCl-catalyzed homocoupling of arylboronic acids under benchtop conditions: Synthesis of biphenyls

(Ph3P)AuCl was discovered to be a powerful catalyst in the homocoupling of arylboronic acids and potassium aryltrifluoroborates for the synthesis of symmetrical biaryls. The reactions take place under benchtop reaction conditions in 96% EtOH at temperatures between rt and 50 °C with no exclusion of air or humidity, in the presence of F-TEDA (Selectfluor™) as an oxidant. The procedure is very functional group tolerant, and affords the corresponding biaryls in high yields with large substrate scope (26 examples).

8‐1: Invited Paper: High Mobility Poly‐Crystalline Oxide TFT Achieving Mobility over 50 cm2/Vs and High Level of Uniformity on the Large Size Substrates

We have successfully developed stable poly‐crystalline oxide semiconductor (Poly‐OS) as channels of TFT on Gen.6 glass substrates. This technology has significantly improved mobility and stability at the same time, achieving both extremely low off‐state current similar to conventional oxide TFTs and high on‐state current equivalent to LTPS TFTs.

Direct Organocatalytic Chemoselective Reductive Alkylation of Chiral 2-Aroylcyclopropanecarbaldehydes: Scope and Applications.

We developed a simple and practically feasible protocol for the chemoselective coupling of optically active functionally rich 2-aroylcyclopropanecarbaldehydes with various CH acids or active methylene compounds under 10 mol % of (s)-proline in the presence of Hantzsch ester as a hydrogen source through a three-component reductive alkylation reaction. The metal-free, organocatalytic selective reductive C-C coupling method has wide advantages/applications like no epimerization, no ring opening, high carbonyl control, and large substrate scope, generating only monoalkylated 2-aroylcyclopropanes, and the resulting chiral products can be synthons in medicinal to material chemistry. We have also shown the synthetic applications of chiral CH-acid-containing 2-aroylcyclopropanes 5 by transforming them into the interesting molecules of pyrimidine analogues 8, dimethyl cyclopropane-malonates 9, functionally rich dihydropyran 10, cyclopropane-alcohols 11, and cyclopropane-olefins 12/13. Many of these chiral products 5-13 can serve as excellent building blocks for the synthesis of value-added small molecules, natural products, pharmaceuticals, and their analogues.

Surface Acoustic Waves Equip Materials with Active De‐Icing Functionality: Unraveled Glaze Ice De‐Icing Mechanisms and Application to Centimeter‐Scale Transparent Surfaces

Enabling active de‐icing functionality on low heat conductive and transparent materials is a requirement for several seminal industries in critical economic sectors. However, developing efficient and environmentally friendly de‐icing methods still fails because of compatibility problems with large‐scale devices and real‐world conditions. In this paper, de‐icing several square centimeters covered with thick layers of glaze ice is approached through nanoscale activation by surface acoustic waves (SAWs). De‐icing functionality is demonstrated with a self‐supported piezoelectric material (LiNbO3) and a piezoelectric film (ZnO) deposited on fused silica, the latter system proving the compatibility of the method with materials of practical relevance. Its applicability to large and transparent substrates is demonstrated by placing the interdigitated electrodes (IDTs) required for activation close to the substrate's edges, leaving most of the surface unaltered. The de‐icing mechanism of glaze ice by SAW activation is revealed by simulating the SAW propagation on ice‐covered surfaces and by experimental analysis of the ice melting process. This involves a combination of ice mechanical stress activation and heating through the initially formed water/ice front. Possible Joule effects due to ohmic losses in the IDTs have been discarded, monitoring local temperature variations during SAW activation at and out of resonance conditions.

MOVPE growth of AlN and AlGaN films on N-polar annealed and sputtered AlN templates

We performed metalorganic vapor phase epitaxy (MOVPE) growth of AlN (MOVPE-AlN) and AlGaN films on N-polar face-to-face annealed and sputtered AlN templates (N-polar FFA Sp-AlN) on sapphire substrates. The off-cut angle of the sapphire substrates was varied from 0.2° to 6.0°. The effects of the off-cut angle on the surface morphology and crystallinity of the N-polar MOVPE-AlN and AlGaN were elucidated. The results showed that the crystallinities of N-polar FFA Sp-AlN and MOVPE-AlN were independent of the off-cut angle. The threading dislocation density (TDD) was estimated to be approximately 5.0 × 108cm−2 by using values of the X-ray rocking curve full-width at half maximum. In comparison, the density of the hillocks on the MOVPE-AlN surfaces was suppressed, and the surface flatness was improved by increasing the off-cut angle of the sapphire substrate. The crystallinity of the AlGaN was improved by increasing the off-cut angle. Our results prove that N-polar AlN and AlGaN films with smooth surfaces and low TDDs could be achieved by MOVPE on N-polar FFA Sp-AlN with a large substrate off-cut angle of 6.0°.

Large-Scale Terahertz Sensor Array Module With Antenna-Coupled Microbolometers on Glass Substrate With Sigma–Delta ADC Readout ASIC

We describe the design, fabrication and demonstration of a terahertz sensor array module, designed to operate over 250-350GHz. The antenna coupled microbolometer was fabricated on a glass substrate with an integrated array of pixel switches and row multiplexing circuitry implemented with LTPS (Low Temperature PolySilicon) thin film transistors. While other microbolometer arrays have been reported for the upper Terahertz bands, we focus on lower frequencies where adequate semiconductor sources are available potentially enabling important medical and security applications. The devices were fabricated in a Gen 3.5 flat panel manufacturing facility implementing what we call Large Area MEMS Platform (LAMP) surface micromachining process, providing a path to low-cost manufacturing. Individual pixels were defined on a 0.7mm pitch across an array of 128x128 pixels in this first demonstration. Since flat panel fabrication capabilities use large, single-shot reticle masks and large glass substrates, physically larger arrays can be manufactured without mask stitching. An ROIC (readout integrated circuit) was demonstrated to support the THz sensor panel with 648 input channels, each providing an independent sigma delta ADC with excellent uniformity and 12 effective number of bits. An early demonstration of the sensor array is described, imaging a metallic knife hidden in a cardboard envelope.

6.1: Adoption of Silicon Blue Semiconductor Laser Diode in Dehydrogenation of LTPS TFT Manufacturing

We have investigated de‐hydrogenation of amorphous film using CW blue light semiconductor laser annealing (BLDA). Dehydrogenation of hydrogen content as high as 20% can be implemented by using BLDA. This technology can be applied for large substrate beyond G8. We will report related experiment results in this paper.

Enhanced WPT structures via EC-SRR-based metasurfaces

PurposeThe purpose of this paper is to present a family of robust metasurface-oriented wireless power transfer systems with improved efficiency and size compactness. The effect of geometric and structural features on the overall efficiency and miniaturisation is elaborately studied, while the presence of substrate losses is, also, considered. Moreover, to further enhance the performance, possible means for reducing the operating frequency, without comprising the unit-cell size, are proposed.Design/methodology/approachThe key element of the design technique is the edge-coupled split-ring resonators patterned in various metasurface configurations and optimally placed to increase the total efficiency. To this goal, a rigorous three-dimensional algorithm, launching a new high-order prism macroelement, is developed in this paper for the fast evaluation of the required quantities. The featured scheme can host diverse approximation orders, while it is drastically more economical than existing methods. Hence, the demanding wireless power transfer systems are precisely modelled via reduced degrees of freedom, without the need to conduct large-scale simulations.FindingsNumerical results, compared with measured data from fabricated prototypes, validate the design methodology and prove its competence to provide enhanced metasurface wireless power transfer systems. An assortment of optimized 3 x 3 and 5 x 5 metamaterial setups is investigated, and interesting deductions, regarding the impact of the inter-element gaps, the distance between the transmitting and receiving components and the substrate losses, are derived. Also, the proposed vector macroelement technique overwhelms typical implementations in terms of computational burden, particularly when combined with the relevant commercial software packages.Originality/valueSystematic design of advanced real-world wireless power transfer structures through optimally selected metasurfaces with fully controllable electromagnetic properties is presented. The analysis is performed by means of a rapid prism macroelement methodology, which leads to very confined meshes, accurate results and significantly reduced overhead. The selected metamaterial resonators are found to be very flexible and reconfigurable, even in the case of large substrate conductivity losses, whereas their contribution to the system’s total efficiency is decisive.

Large-area synthesis of high electrical performance MoS2 by a commercially scalable atomic layer deposition process

This work demonstrates a large area process for atomically thin 2D semiconductors to unlock the technological upscale required for their commercial uptake. The new atomic layer deposition (ALD) and conversion technique yields large area performance uniformity and tunability. Like graphene, 2D Transition Metal Dichalcogenides (TMDCs) are prone to upscaling challenges limiting their commercial uptake. They are challenging to grow uniformly on large substrates and to transfer on alternative substrates while they often lack in large area electrical performance uniformity. The scalable ALD process of this work enables uniform growth of 2D TMDCs on large area with independent control of layer thickness, stoichiometry and crystallinity while allowing chemical free transfers to application substrates. Field effect transistors (FETs) fabricated on flexible substrates using the process present a field effect mobility of up to 55 cm2/Vs, subthreshold slope down to 80 mV/dec and on/off ratios of 107. In addition, non-volatile memory transistors using ferroelectric FETs (FeFETs) operating at ±5 V with on/off ratio of 107 and a memory window of 3.25 V are demonstrated. These FeFETs demonstrate state-of-the-art performance with multiple state switching, suitable for one-transistor non-volatile memory and for synaptic transistors revealing the applicability of the process to flexible neuromorphic applications.

Co2+ to Al3+ Substitution Induced Dual-Site Synergistic Catalysis to Friedel-Crafts Alkylation Reactions.

The dual-site synergistic effect in heterogeneous catalysis is quite interesting, and also complex because at least two substrate molecules are adsorbed or activated on the catalyst surface, which apparently needs two spatially separated and functionally independent active sites. It would become more difficult when the substrate molecules are large ones. The replacement of Al3+ in Al4 B6 O15 lattice with Co2+ leads to the formation of unsaturated Co2+ (4-fold coordination) along with oxygen vacancies (Ov ). The former one behaves as a medium-strength Lewis acid site, and can adsorb and activate molecules with a nitro group (e. g., β-nitrostyrene). The latter one can adsorb and activate oxygen species, which further activates the indole derivatives. Next, the spatially separated dual sites on the catalyst surface can synergistically and efficiently catalyze their Friedel-Crafts alkylation reactions under mild conditions. The high durability can be proved by the as-maintained high yields, that is, 98, 93, 96, 92 and 90 % for 5 runs, respectively. The reaction kinetics obey the second-order characteristic. Annealing under hydrogen condition can further generate more surficial Ov , leading to an improvement to the catalytic activity. A simple and probably routine aliovalent doping endows such a complex synergistic catalysis involving two large substrate molecules, providing an inspired perspective of developing dual-site catalysts.

Rutile TiO2 thin films growth on glass substrates with generation of high entropy interface

TiO2 thin films obtained through Reactive Magnetron Sputtering (RMS) have been extensively studied in the last decades for several applications as photocatalyst and self-cleaning coats. However, reactive deposition through MS onto large area substrates can be troublesome due to inhomogeneous films thickness and poor adhesion between film and substrate. This paper investigates the deposition of TiO2 thin films on glass substrates through a two steps method, namely: 1- deposition of nanometer thickness Ti metallic films on glass substrate, through triode magnetron sputtering; 2- oxidation of the Ti film through thermal treatment in atmospheric air, to obtain stoichiometric TiO2 layers. The film oxidation was performed concomitantly to the glass thermal treatment carried out at 650 °C. Analysis through XPS depth profile indicates the formation of a chemically graded high entropy interlayer due to the interdiffusion of atoms from substrate to film and vice-versa, during the thermal treatment. The high entropy interface layer contributes to reduces the mismatch between the film and the substrate lattice, resulting in an improvement of film adhesion. The badgap analysis through Tauc method show two energy values, namely 3.2 eV and 2.9 eV, which can be attributed to TiO2-rutile layer and the high entropy zone at interface, composed by [Ca-Na-Si-Ti]Ox oxides. The wettability results show that the contact angle may be as low as 10° between a deionized water drop and the rutile-TiO2 surface, after activation with UV light irradiation, which is characteristic of super-hydrophilic surface.

Climate change impacts on native cutthroat trout habitat in Colorado streams

AbstractHeadwater streams support vital aquatic habitat yet are vulnerable to changing climate due to their high elevation and small size. Coldwater fish are especially sensitive to the altered streamflow and water temperature regimes during summer low flow periods. Though previous studies have provided insights on how changes in climate and alterations in stream discharge may affect habitat availability for various native cutthroat trout species, suitable physical habitats have not been evaluated under future climate projections for the threatened Greenback Cutthroat Trout (GBCT) native to headwater regions of Colorado, USA. Thus, this study used field data collected from selected headwater streams across the current distribution of GBCT to construct one‐dimensional hydraulic models to evaluate streamflow and physical habitat under four future climate projections. Results illustrate reductions in both predicted streamflow and physical habitat for all future climate projections across study sites. The projected mean summer streamflow shows greater decline (−52% on average) compared to the projected decline in mean August flow (−21% on average). Moreover, sites located at a relative higher elevation with larger substrate and steeper slope were projected to experience more reductions in physical habitat due to streamflow reductions. Specifically, streams with step‐pool morphologies may experience grater changes in available habitat compared to pool‐riffle streams. Future climate change studies related to coldwater fish that examine spatial variation in flow alteration could provide novel data to complement the existing literature on the thermal characteristics. Tailoring reintroduction and management efforts for GBCT to the individual headwater stream with adequate on‐site monitoring could provide a more holistic conservation approach.

Defensin Interactions in Relation to Monoclonal and Disease-Related Proteinase 3 Antibodies Binding at the Catalytic Site.

Proteinase 3 (PR3) is a neutrophil granulocyte enzyme and an autoantigen found in several forms of vasculitis. Due to the diagnostic and clinical importance of antibodies (Abs) to PR3, it is important to characterize the protein and the nature of its epitopes. Here, we have characterized PR3 monoclonal antibodies (MAbs) and disease-associated Abs and their dependency on the PR3 structure and modifications, especially interactions with α-defensins. Three MAbs (HYB 172-01, 172-04, 172-05), which bind to PR3 in its native and denatured forms and provide the disulphide bridges, were intact. α-1-antitrypsin (AT) binds to purified human neutrophil granulocyte PR3 and inhibits its proteolytic activity, towards a small synthetic peptide substrate and a large protein substrate (casein). AT also inhibited the binding of the three MAbs to PR3, indicating that they bind in a region affected by AT binding. However, the MAbs did not inhibit PR3 proteolytic activity with a small substrate, showing that they bound at the active site without restricting access to the substrate cleft. Patient-derived Abs showed essentially the same characteristics as the MAbs, with important implications for vasculitis diagnostics and pathophysiology. Current findings illustrate that PR3 epitopes depend on the three-dimensional structure of the PR3/defensin complex, and that the epitopes depend to a smaller or larger degree on PR3/defensin associations.