Anisotropic Resistivity Size Effect in Epitaxial Mo(001) and Mo(011) Layers.

Mo(001) and Mo(011) layers with thickness = 4-400 nm are sputter-deposited onto MgO(001) and α-AlO(112¯0) substrates and their resistivity is measured in situ and ex situ at room temperature and 77 K in order to quantify the resistivity size effect. Both Mo(001) and Mo(011) layers are epitaxial single crystals and exhibit a resistivity increase with decreasing due to electron surface scattering that is well described by the classical Fuchs and Sondheimer model. Data fitting yields room temperature effective electron mean free paths 14.

Giant pyroelectricity in nanomembranes.

Pyroelectricity describes the generation of electricity by temporal temperature change in polar materials. When free-standing pyroelectric materials approach the 2D crystalline limit, how pyroelectricity behaves remained largely unknown. Here, using three model pyroelectric materials whose bonding characters along the out-of-plane direction vary from van der Waals (InSe), quasi-van der Waals (CsBiNbO) to ionic/covalent (ZnO), we experimentally show the dimensionality effect on pyroelectricity and the relation between lattice dynamics and pyroelectricity.

Tunable Infrared Plasmonic Properties of Epitaxial TiMgN(001) Layers.

Optical transmission and reflection spectra in combination with ellipsometry and transport measurements on epitaxial rocksalt structure TiMgN(001) layers with 0.00 ≤ ≤ 0.49 are employed to explore their potential as refractory infrared plasmonic materials.

A chiral switchable photovoltaic ferroelectric 1D perovskite.

Spin and valley degrees of freedom in materials without inversion symmetry promise previously unknown device functionalities, such as spin-valleytronics. Control of material symmetry with electric fields (ferroelectricity), while breaking additional symmetries, including mirror symmetry, could yield phenomena where chirality, spin, valley, and crystal potential are strongly coupled. Here we report the synthesis of a halide perovskite semiconductor that is simultaneously photoferroelectricity switchable and chiral.

A Reconfigurable Remotely Epitaxial VO Electrical Heterostructure.

The reconfigurability of the electrical heterostructure featured with external variables, such as temperature, voltage, and strain, enabled electronic/optical phase transition in functional layers has great potential for future photonics, computing, and adaptive circuits. VO has been regarded as an archetypal phase transition building block with superior metal-insulator transition characteristics. However, the reconfigurable VO-based heterostructure and the associated devices are rare due to the fundamental challenge in integrating high-quality VO in technologically important substrates.

Publisher Correction: Carrier lifetime enhancement in halide perovskite via remote epitaxy.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Carrier lifetime enhancement in halide perovskite via remote epitaxy.

Crystallographic dislocation has been well-known to be one of the major causes responsible for the unfavorable carrier dynamics in conventional semiconductor devices. Halide perovskite has exhibited promising applications in optoelectronic devices. However, how dislocation impacts its carrier dynamics in the 'defects-tolerant' halide perovskite is largely unknown.

A heterodimeric glutathione -transferase that stereospecifically breaks lignin's β()-aryl ether bond reveals the diversity of bacterial β-etherases.

Lignin is a heterogeneous polymer of aromatic subunits that is a major component of lignocellulosic plant biomass. Understanding how microorganisms deconstruct lignin is important for understanding the global carbon cycle and could aid in developing systems for processing plant biomass into valuable commodities. Sphingomonad bacteria use stereospecific glutathione -transferases (GSTs) called β-etherases to cleave the β-aryl ether (β-O-4) bond, the most common bond between aromatic subunits in lignin.

uses a Nu-class glutathione -transferase as a glutathione lyase in breaking the β-aryl ether bond of lignin.

As a major component of plant cell walls, lignin is a potential renewable source of valuable chemicals. Several sphingomonad bacteria have been identified that can break the β-aryl ether bond connecting most phenylpropanoid units of the lignin heteropolymer. Here, we tested three sphingomonads predicted to be capable of breaking the β-aryl ether bond of the dimeric aromatic compound guaiacylglycerol-β-guaiacyl ether (GGE) and found that metabolizes GGE at one of the fastest rates thus far reported.

Enzymatic Depolymerization of Lignin with Release of Syringyl, Guaiacyl, and Tricin Units.

New environmentally sound technologies are needed to derive valuable compounds from renewable resources. Lignin, an abundant polymer in terrestrial plants comprised predominantly of guaiacyl and syringyl monoaromatic phenylpropanoid units, is a potential natural source of aromatic compounds. In addition, the plant secondary metabolite tricin is a recently discovered and moderately abundant flavonoid in grasses.

Biochemical transformation of lignin for deriving valued commodities from lignocellulose.

The biochemical properties of lignin present major obstacles to deriving societally beneficial entities from lignocellulosic biomass, an abundant and renewable feedstock. Similar to other biopolymers such as polysaccharides, polypeptides, and ribonucleic acids, lignin polymers are derived from multiple types of monomeric units. However, lignin's renowned recalcitrance is largely attributable to its racemic nature and the variety of covalent inter-unit linkages through which its aromatic monomers are linked.

Structural and Biochemical Characterization of the Early and Late Enzymes in the Lignin β-Aryl Ether Cleavage Pathway from Sphingobium sp. SYK-6.

There has been great progress in the development of technology for the conversion of lignocellulosic biomass to sugars and subsequent fermentation to fuels. However, plant lignin remains an untapped source of materials for production of fuels or high value chemicals. Biological cleavage of lignin has been well characterized in fungi, in which enzymes that create free radical intermediates are used to degrade this material.

Structural Basis of Stereospecificity in the Bacterial Enzymatic Cleavage of β-Aryl Ether Bonds in Lignin.

Lignin is a combinatorial polymer comprising monoaromatic units that are linked via covalent bonds. Although lignin is a potential source of valuable aromatic chemicals, its recalcitrance to chemical or biological digestion presents major obstacles to both the production of second-generation biofuels and the generation of valuable coproducts from lignin's monoaromatic units. Degradation of lignin has been relatively well characterized in fungi, but it is less well understood in bacteria.

A group of sequence-related sphingomonad enzymes catalyzes cleavage of β-aryl ether linkages in lignin β-guaiacyl and β-syringyl ether dimers.

Lignin biosynthesis occurs via radical coupling of guaiacyl and syringyl hydroxycinnamyl alcohol monomers (i.e., "monolignols") through chemical condensation with the growing lignin polymer.

Stereochemical features of glutathione-dependent enzymes in the Sphingobium sp. strain SYK-6 β-aryl etherase pathway.

Glutathione-dependent enzymes play important protective, repair, or metabolic roles in cells. In particular, enzymes in the glutathione S-transferase (GST) superfamily function in stress responses, defense systems, or xenobiotic detoxification. Here, we identify novel features of bacterial GSTs that cleave β-aryl ether bonds typically found in plant lignin.

Benzoyl coenzyme a pathway-mediated metabolism of meta-hydroxy-aromatic acids in Rhodopseudomonas palustris.

Photoheterotrophic metabolism of two meta-hydroxy-aromatic acids, meta-, para-dihydroxybenzoate (protocatechuate) and meta-hydroxybenzoate, was investigated in Rhodopseudomonas palustris. When protocatechuate was the sole organic carbon source, photoheterotrophic growth in R. palustris was slow relative to cells using compounds known to be metabolized by the benzoyl coenzyme A (benzoyl-CoA) pathway.

"Candidatus Accumulibacter" population structure in enhanced biological phosphorus removal sludges as revealed by polyphosphate kinase genes.

We investigated the fine-scale population structure of the "Candidatus Accumulibacter" lineage in enhanced biological phosphorus removal (EBPR) systems using the polyphosphate kinase 1 gene (ppk1) as a genetic marker. We retrieved fragments of "Candidatus Accumulibacter" 16S rRNA and ppk1 genes from one laboratory-scale and several full-scale EBPR systems. Phylogenies reconstructed using 16S rRNA genes and ppk1 were largely congruent, with ppk1 granting higher phylogenetic resolution and clearer tree topology and thus serving as a better genetic marker than 16S rRNA for revealing population structure within the "Candidatus Accumulibacter" lineage.

Polyphosphate kinase genes from full-scale activated sludge plants.

The performance of enhanced biological phosphorus removal (EBPR) wastewater treatment processes depends on the presence of bacteria that accumulate large quantities of polyphosphate. One such group of bacteria has been identified and named Candidatus Accumulibacter phosphatis. Accumulibacter-like bacteria are abundant in many EBPR plants, but not much is known about their community or population ecology.

Growth of Y-shaped nanorods through physical vapor deposition.

This work presents a proposed mechanism for fabricating Y-shaped nanorods, demonstrates the feasibility of the proposal through classical molecular dynamics simulations, and validates the simulations through magnetron sputter deposition experiments. The proposed mechanism relies primarily on the formation of stacking faults during deposition and to a lesser degree on diffusion kinetics and geometrical shadowing. Applications of the proposed mechanism may enable the design of nanorod arrays with controlled branching.