Cytotoxicity of Three CO2/Butadiene-Derived Monomers.

The utilization of carbon dioxide (CO2) as a raw material for synthesizing CO2-based polymers presents a promising large-scale strategy for its consumption and transformation. The recent successful syntheses of degradable and monomer-recyclable polyesters from CO2 and butadiene-derived monomers represent a series of significant advancements. These monomers include 1,2-ethylidene-6-vinyl-tetrahydro-2H-pyran-2-one (δ-L), 3,6-diethyl-tetrahydro-2H-pyran-2-one (HL) and 3-ethyl-6-vinyltetrahydro2H-pyran-2-one (δLH2).

Monomer-Recyclable Polyester from CO and 1,3-Butadiene.

Synthesis of monomer-recyclable polyesters solely from CO and bulk olefins holds great potential in significantly reducing CO emissions and addressing the issue of plastic pollution. Due to the kinetic disadvantage of direct copolymerization of CO and bulk olefins compared to homopolymerization of bulk olefins, considerable research attention has been devoted to synthesis of polyester via the ring-opening polymerization (ROP) of a six-membered disubstituted lactone intermediate, 1,2-ethylidene-6-vinyl-tetrahydro-2H-pyran-2-one (𝜹-L), obtained from telomerization of CO and 1,3-butadiene. However, the conjugate olefin on the six-membered ring of 𝜹-L leads to serious Michael addition side reactions.

What Metals Should Be Used to Mediate Electrosynthesis of Ammonia from Nitrogen and Hydrogen from a Thermodynamic Standpoint?

Recently, metal-mediated electrochemical conversion of nitrogen and hydrogen to ammonia (M-eNRRs) has been attracting intense research attention as a potential route for ammonia synthesis under ambient conditions. However, which metals should be used to mediate M-eNRRs remains unanswered. This work provides an extensive comparison of the energy consumption in the classical Haber Bosch (H-B) process and the M-eNRRs.

Sustainable Copolymer Synthesis from Carbon Dioxide and Butadiene.

Carbon dioxide (CO) has long been recognized as an ideal C1 feedstock comonomer for producing sustainable materials because it is renewable, abundant, and cost-effective. However, activating CO presents a significant challenge because it is highly oxidized and stable. A CO/butadiene-derived δ-valerolactone (EVP), generated via palladium-catalyzed telomerization between CO and butadiene, has emerged as an attractive intermediate for producing sustainable copolymers from CO and butadiene.

Experimentally-calibrated estimation of CO removal potentials of enhanced weathering.

Enhanced weathering (EW) of (ultra)mafic rocks is widely considered as a promising option for carbon dioxide removal (CDR). However, accurately measuring its CDR potential remains unavailable due to sluggish weathering process. Previous models have estimated annual CDR potentials ranging from 1 to 95 Gt by 2100, with the maximum significantly exceeding the anthropogenic CO emissions in 2021 (approximately 41 Gt).

A reusable, impurity-tolerant and noble metal-free catalyst for hydrocracking of waste polyolefins.

One-step conversion of low-purity polyolefins to value-added products without pretreatments represents a great opportunity for chemical recycling of waste plastics. However, additives, contaminants, and heteroatom-linking polymers tend to be incompatible with catalysts that break down polyolefins. Here, we disclose a reusable, noble metal-free and impurity-tolerant bifunctional catalyst, MoS-Hbeta, for hydroconversion of polyolefins into branched liquid alkanes under mild conditions.

Chemically Recyclable CO -Based Solid Polyesters with Facile Property Tunability.

Synthesizing chemically recyclable solid polymeric materials is a significant strategy to potentially achieve carbon neutral production of new polymers and alleviate plastic pollution, especially when the synthesis is based on CO and inexpensive co-feedstocks available in large scales. Additionally, polymeric materials should have high enough molecular weight to exhibit distinguished properties from low molar mass polymers to serve for a broader range of application scenarios. However, up to now, strategies for developing solid-state CO -based chemically recyclable polyesters with both high molecular weight and facile property tunability are still unprecedented.

Chemically recyclable polyesters from CO, H, and 1,3-butadiene.

Chemically recyclable solid polymeric materials with commercializable properties only using CO and inexpensive bulk chemicals as chemical feedstock can open a brand-new avenue to economically viable, large-scale fixation of CO over a long period of time. Despite previous great advancements, development of such a kind of CO-based polymers remains a long-term unsolved research challenge of great significance. Herein, we reported the first methodology to polymerize six-membered lactone with two substituents vicinal to the ester group (), a compound previously found to be non-polymerizable.

Phenolate-bonded bis(μ-oxido)-bis-copper(III) intermediates: hydroxylation and dehalogenation reactivities.

Exogenous phenolate -hydroxylation by copper oxidants formed from dioxygen is generally thought to occur through one of two limiting mechanisms defined by the structure of the active oxidant: an electrophilic μ-η:η-peroxo-bis-copper(II) species as found in the oxygenated form of the binuclear copper enzyme tyrosinase (oxyTyr), or an isomeric bis(μ-oxido)-bis-copper(III) species (O) with ligated phenolate(s) as evidenced by most synthetic systems. The characterization of the latter is limited due to their limited thermal stability. This study expands the scope of an O species with ligated phenolate(s) using ,'-di--butyl-1,3-propanediamine (DBPD), a flexible secondary diamine ligand.

Low-Cost Polyethylene Terephthalate Fluidic Sensor for Ultrahigh Accuracy Measurement of Liquid Concentration Variation.

A low-cost polyethylene terephthalate fluidic sensor (PET-FS) is demonstrated for the concentration variation measurement on fluidic solutions. The PET-FS consisted of a triangular fluidic container attached with a birefringent PET thin layer. The PET-FS was injected with the test liquid solution that was placed in a common path polarization interferometer by utilizing a heterodyne scheme.

A computational evaluation of targeted oxidation strategy (TOS) for potential inhibition of SARS-CoV-2 by disulfiram and analogues.

In the new millennium, the outbreak of new coronavirus has happened three times: SARS-CoV, MERS-CoV, and SARS-CoV-2. Unfortunately, we still have no pharmaceutical weapons against the diseases caused by these viruses. The pandemic of SARS-CoV-2 reminds us the urgency to search new drugs with totally different mechanism that may target the weaknesses specific to coronaviruses.

Molecular Chirality Detection with Periodic Arrays of Three-Dimensional Twisted Metamaterials.

Rapid detection of the handiness of chiral molecules is an important topic for pharmaceutical industries because chiral drugs with opposing handiness sometimes exhibit unwanted side effects. In this research, a rapid optical method is proposed to determine the handiness of the chiral drug "Thalidomide". The platform is a large array of three-dimensional (3D) twisted metamaterials fabricated with a novel method by combining nanospherical-lens lithography (NLL) and hole-mask lithography (HML).

Temperature-Resolved Cryo-EM Uncovers Structural Bases of Temperature-Dependent Enzyme Functions.

Protein functions are temperature-dependent, but protein structures are usually solved at a single (often low) temperature because of limitations on the conditions of crystal growth or protein vitrification. Here we demonstrate the feasibility of solving cryo-EM structures of proteins vitrified at high temperatures, solve 12 structures of an archaeal ketol-acid reductoisomerase (KARI) vitrified at 4-70 °C, and show that structures of both the Mg form (KARI:2Mg) and its ternary complex (KARI:2Mg:NADH:inhibitor) are temperature-dependent in correlation with the temperature dependence of enzyme activity. Furthermore, structural analyses led to dissection of the induced-fit mechanism into ligand-induced and temperature-induced effects and to capture of temperature-resolved intermediates of the temperature-induced conformational change.

Scalable direct N-methylation of drug-like amines using CO/CO by simple inorganic base catalysis.

With the growing urgency of potential catastrophic climate changes due to anthropogenic CO emissions, numerous efforts have been devoted to development of synthetic protocols using CO as a building block in organic reactions, but the general applicability to complex drug-like substrates remains a challenge. We develop a general protocol for scalable direct N-methylation of a wide-scope drug-like amines using CO and polymethylhydrosiloxane-a nontoxic, aerobically-stable hydrosilane considered as an industrial waste-via simple inorganic base catalysis. A rare application of the Sabatier principle in organic chemistry led to the discovery of cheap, nontoxic KPO as an efficient catalyst.

Air-Tolerant Direct Thiol Esterification with Carboxylic Acids Using Hydrosilane via Simple Inorganic Base Catalysis.

Direct thioesterification of carboxylic acids with thiols using nontoxic activation agents is highly desirable. Herein, an efficient and practical protocol using safe and inexpensive industrial waste polymethylhydrosiloxane as the activation agent and KPO with 18-crown-6 as a catalyst is described. Various functional groups on carboxylic acid and thiol substituents can be tolerated by the present system to afford thioesters in yields of 19-100%.

Use of Cryo-EM To Uncover Structural Bases of pH Effect and Cofactor Bispecificity of Ketol-Acid Reductoisomerase.

While cryo-EM is revolutionizing structural biology, its impact on enzymology is yet to be fully demonstrated. The ketol-acid reductoisomerase (KARI) catalyzes conversion of (2 S)-acetolactate or (2 S)-aceto-2-hydroxybutyrate to 2,3-dihydroxy-3-alkylbutyrate. We found that KARI from archaea Sulfolobus solfataricus (Sso-KARI) is unusual in being a dodecamer, bispecific to NADH and NADPH, and losing activity above pH 7.

Universal Anticancer Cu(DTC) Discriminates between Thiols and Zinc(II) Thiolates Oxidatively.

Aerobic organisms must rely on abundant intracellular thiols to reductively protect various vital functional units, especially ubiquitous zinc(II) thiolate sites of proteins, from deleterious oxidations resulting from oxidizing environments. Disclosed here is the first well-defined model study for reactions between zinc(II) thiolate complexes and copper(II) complexes. Among all the studied ligands of copper(II), diethyldithiocarbamate (DTC) displays a unique redox-tuning ability that enables copper(II) to resist the reduction by thiols while retaining its ability to oxidize zinc(II) thiolates to form disulfides.

Foot-and-mouth disease outbreaks due to an exotic serotype Asia 1 virus in Myanmar in 2017.

In January 2017, two villages located in Rakhine State of Myanmar reported clinical signs in cattle suggestive of foot-and-mouth disease virus (FMDV) infection. Laboratory analysis identified the outbreak virus as FMDV serotype Asia 1, which represented the first detection of this serotype in Myanmar since 2005 and in the region of South-East Asia (SEA) since 2007. Genetic analysis revealed that the outbreak virus was different from historical viruses from Myanmar and was more closely related to viruses circulating in Bangladesh and India during 2012-2013, indicating that a novel viral introduction had occurred.

Polarization-Selecting III-Nitride Elliptical Nanorod Light-Emitting Diodes Fabricated with Nanospherical-Lens Lithography.

Current-injected elliptical nanorod light-emitting diodes (LEDs) are demonstrated to emit polarized light with a bottom-emitting configuration. The polarization ratio of the electroluminescence reaches 3.17 when the length of the minor axis for the elliptical nanorods is as small as 150 nm.

NADH/NADPH bi-cofactor-utilizing and thermoactive ketol-acid reductoisomerase from Sulfolobus acidocaldarius.

Ketol-acid reductoisomerase (KARI) is a bifunctional enzyme in the second step of branched-chain amino acids biosynthetic pathway. Most KARIs prefer NADPH as a cofactor. However, KARI with a preference for NADH is desirable in industrial applications including anaerobic fermentation for the production of branched-chain amino acids or biofuels.

Highly Efficient Synthesis of Functionalizable Polymers from a CO/1,3-Butadiene-Derived Lactone.

Making polymers from CO and olefins has been long sought and is of particular significance for chemical utilizations of CO. Herein, high molecular-weight polymers with 29 wt % CO were obtained by polymerizing a δ-lactone () synthesized from a C-C coupling reaction between CO and 1,3-butadiene, an economical large-volume chemical that can also be derived from top biomass platform chemicals. Although has been known for many years, little was investigated in its polymerization.

The Arginine Pairs and C-Termini of the Sso7c4 from Sulfolobus solfataricus Participate in Binding and Bending DNA.

The Sso7c4 from Sulfolobus solfataricus forms a dimer, which is believed to function as a chromosomal protein involved in genomic DNA compaction and gene regulation. Here, we present the crystal structure of wild-type Sso7c4 at a high resolution of 1.63 Å, showing that the two basic C-termini are disordered.

Primary amine stabilization of a dicopper(III) bis(μ-oxo) species: modeling the ligation in pMMO.

Here we report the formation of the first examples of dicopper(III) bis(μ-oxo) complexes ligated by the primary amines, propylenediamine, and N,N,-dimethyl propylenediamine. Stabilization of these new compounds is effected at -125 °C by "core capture"- introduction of exogenous ligand to a preformed dicopper(III) bis(μ-oxo) complex supported by the peralkylated tetramethyl propylenediamine. Primary amine ligation in these compounds matches the single primary amine coordination of the putative active site of particulate methane monooxygenase (pMMO) and polysaccharide monooxygenase.

Toward automated denoising of single molecular Förster resonance energy transfer data.

A wide-field two-channel fluorescence microscope is a powerful tool as it allows for the study of conformation dynamics of hundreds to thousands of immobilized single molecules by Förster resonance energy transfer (FRET) signals. To date, the data reduction from a movie to a final set containing meaningful single-molecule FRET (smFRET) traces involves human inspection and intervention at several critical steps, greatly hampering the efficiency at the post-imaging stage. To facilitate the data reduction from smFRET movies to smFRET traces and to address the noise-limited issues, we developed a statistical denoising system toward fully automated processing.