Unprecedented Ferroelectricity and Ferromagnetism in a Cr2+ -Based Two-Dimensional Hybrid Perovskite.

Organic-inorganic hybrid perovskites (OIHPs) have gained tremendous interest for their rich functional properties. However, the coexistence of more than one of ferroelectricity, ferromagnetism and ferroelasticity has been rarely found in OIHPs. Herein, we report a two-dimensional Cr2+ -based OIHP, [3,3-difluorocyclobutylammonium]2 CrCl4 ([DFCBA]2 CrCl4 ), which shows both ferroelectricity and ferromagnetism. It undergoes a 4/mmmFm type ferroelectric phase transition at a temperature as high as 387 K and shows multiaxial ferroelectricity with a saturate polarization of 2.1 µC cm-2 . It acts as a soft ferromagnet with a Curie temperature of 32.6 K. This work throws light on the exploration of OIHPs with the coexistence of ferroelectricity and ferromagnetism for applications in future multifunctional smart devices.

Spin-Electric Coupling with Anisotropy-Induced Vanishment and Enhancement in Molecular Ferroelectrics.

Manipulating quantum properties by electric fields using spin-electric coupling (SEC) effects promises spatial addressability. While several studies about inorganic materials showing the SEC functionality have been reported, the vastly tunable crystal structures of molecular ferroelectrics provide a range of rationally designable materials yet to be exploited. In this work, Mn2+-doped molecular ferroelectrics are chosen to experimentally demonstrate the feasibility of achieving the quantum coherent SEC effect in molecular ferroelectrics for the first time. The electric field pulse applied between Hahn-echo pulses in electron paramagnetic resonance (EPR) experiments causes controllable phase shifts via manipulating of the zero-field splitting (ZFS) of the Mn(II) ions. Detailed investigations of the aMn crystal showed unexpected SEC vanishment and enhancement at different crystal orientations, which were elucidated by studying the spin Hamiltonian and magnetic anisotropy. With the enhanced SEC efficiency being achieved (0.68 Hz m/V), this work discovers an emerging material library of molecular ferroelectrics to implement coherent quantum control with selective and tunable SEC effects toward highly scalable quantum gates.

Marine Bioactive Compounds as Nutraceutical and Functional Food Ingredients for Potential Oral Health.

Oral diseases have received considerable attention worldwide as one of the major global public health problems. The development of oral diseases is influenced by socioeconomic, physiological, traumatic, biological, dietary and hygienic practices factors. Currently, the main prevention strategy for oral diseases is to inhibit the growth of biofilm-producing plaque bacteria. Tooth brushing is the most common method of cleaning plaque, aided by mouthwash and sugar-free chewing gum in the daily routine. As the global nutraceutical market grows, marine bioactive compounds are becoming increasingly popular among consumers for their antibacterial, anti-inflammatory and antitumor properties. However, to date, few systematic summaries and studies on the application of marine bioactive compounds in oral health exist. This review provides a comprehensive overview of different marine-sourced bioactive compounds and their health benefits in dental caries, gingivitis, periodontitis, halitosis, oral cancer, and their potential use as functional food ingredients for oral health. In addition, limitations and challenges of the application of these active ingredients are discussed and some observations on current work and future trends are presented in the conclusion section.

Coexistence of magnetic and electric orderings in a divalent Cr2+-based multiaxial molecular ferroelectric.

Multiferroic materials have attracted great interest because of their underlying new science and promising applications in data storage and mutual control devices. However, they are still very rare and highly imperative to be developed. Here, we report an organic-inorganic hybrid perovskite trimethylchloromethylammonium chromium chloride (TMCM-CrCl3), showing the coexistence of magnetic and electric orderings. It displays a paraelectric-ferroelectric phase transition at 397 K with an Aizu notation of 6/mFm, and spin-canted antiferromagnetic ordering with a Néel temperature of 4.8 K. The ferroelectricity originates from the orientational ordering of TMCM cations, and the magnetism is from the [CrCl3]- framework. Remarkably, TMCM-CrCl3 is the first experimentally confirmed divalent Cr2+-based multiferroic material as far as we know. A new category of hybrid multiferroic materials is pointed out in this work, and more Cr2+-based multiferroic materials will be expectedly developed in the future.

[Distribution Characteristics of Viruses Microorganisms in a Water Supply System with Combined Ultraviolet Chloramine Disinfection].

To study the effect of combined ultraviolet (UV) chloramine disinfection on viruses in a drinking water supply system, a full-scale experiment was conducted to analyze the distribution, variability, community structure, and hosts of viruses using metagenomics. The results showed that the combined UV chloramine process reduced the number of virus species (6.13%) and gene abundance (51.97%) but did not completely remove the viruses from the water. The United States Environmental Protection Agency (USEPA) report that virus removal efficiencies from water can reach 99%-99.99% based on culturing methods. However, in this study, metagenomic analysis indicated a total virus removal rate of only 93.46%. Therefore, the detection of viruses in water using culturing method cannot reliably detect viruses in drinking water. Caudovirales are the most abundant type of virus in water supply systems and are sensitive to chloramine disinfection. Lentivirus, as a virus that can infect humans and vertebrates, has strong resistance to UV and chloramine disinfection. The main virus hosts in the studied water supply system were bacteria (61.50%). The viruses in the raw water were mainly parasitic in Synechococcus. The dominant virus host was Pseudomonas in both the effluent water and pipe network water. The gene abundance of the Pseudomonas aeruginosa host in the pipe network increased by 342.62%, which requires further attention as a virus risk in pipe network systems. Overall, combined UV chloramine disinfection was more effective at the removal of virus hosts than single UV disinfection (51.97% compared to 0.79%).

Electric field manipulation enhanced by strong spin-orbit coupling: promoting rare-earth ions as qubits.

Quantum information processing based on magnetic ions has potential for applications as the ions can be modified in their electronic properties and assembled by a variety of chemical methods. For these systems to achieve individual spin addressability and high energy efficiency, we exploited the electric field as a tool to manipulate the quantum behaviours of the rare-earth ion which has strong spin-orbit coupling. A Ce:YAG single crystal was employed with considerations to the dynamics and the symmetry requirements. The Stark effect of the Ce3+ ion was observed and measured. When demonstrated as a quantum phase gate, the electric field manipulation exhibited high efficiency which allowed up to 57 π/2 operations before decoherence with optimized field direction. It was also utilized to carry out quantum bang-bang control, as a method of dynamic decoupling, and the refined Deutsch-Jozsa algorithm. Our experiments highlighted rare-earth ions as potentially applicable qubits because they offer enhanced spin-electric coupling which enables high-efficiency quantum manipulation.

[Pollution Characteristics and Emission Coefficients for Volatile Organic Compounds from the Synthetic Leather Industry in Zhejiang Province].

Based on the survey of 175 synthetic leather enterprises in Zhejiang Province, China, in 2014, this paper analyzes the control of volatile organic compounds (VOCs) and, ultimately, screened 161 key enterprises for further research. The results showed that most enterprises take measures to control waste gas; however, there is a distinct problem with the efficiency of exhaust gas collection. The industry used Solvent-based materials. The main VOC pollutants were DMF, toluene, methyl acetate, acetone, ethylacetate, and butanone. The VOC emission coefficient of the synthetic leather industry in Zhejiang was 0.168 kg·m-2. The industry includes polyurethane and polyvinyl chloride processes, for which VOC emission coefficients were 0.170 kg·m-2 and 0.142 kg·m-2, respectively. In addition, the emission coefficient of polyurethane wet processes was 0.191 kg·m-2 and that of dry processes was 0.179 kg·m-2. The emission coefficient for VOCs in post-treatment processes was 0.120 kg·m-2.

Three New Niccolites: High-Temperature Phase Transitions, Prominent Anisotropic Thermal Expansions, Dielectric Anomalies, and Magnetism.

Three new iso-structural ammonium metal formates of [dmpnH2 ][M2 (HCOO)6 ], in which dmpnH2 2+ =N,N'-dimethyl-1,3-propylenediammoium and M=divalent Co, Zn and Mg ions, are reported. They possess niccolite metal formate frameworks with long-shaped cavities for the accommodation of dmpnH2 2+ cations. The three materials display reversible phase transitions of similar mechanism from ordered, antipolar or antiferroelectric, low-temperature phases in space group C2/c, to disordered, paraelectric, high-temperature phases in space group P 3 ‾ 1c, with quite high critical temperatures of 366, 370, and 334 K for Co, Zn, and Mg members, respectively. On warming, the dmpnH2 2+ cation experiences an ordered state with gradual increase of the local vibration motions of the central CH2 and terminal CH3 groups, a partially disordered state with gradually enhanced flipping motion between the major and minor orientations, and finally a twisting or rotating motion after the phase transition, accompanied by prominent anisotropic thermal expansions and dielectric anomalies/relaxations. The phase transition characters and relevant properties also exhibit a subtle metal-dependence. The Co member shows spin-canted antiferromagnetism below the Néel temperature of 16.1 K, with unusual large spontaneous magnetization and coercive field.

Magnetic layered perovskites of [CH3C(NH2)2]2[M(HCOO)4] (M = Co2+ and Ni2+): synthesis, structures and properties.

We present two layered perovskites of the formula [CH3C(NH2)2]2[M(HCOO)4] (M = Co and Ni). The two materials are isostructural and crystallize in the orthorhombic space group Pccn. The structures consist of anionic 100-oriented perovskite or square metal-formate layers and interlayer [CH3C(NH2)2]+ cations. In each layer octahedral M2+ ions are linked by equatorial anti-anti HCOO- bridges and are further coordinated by apical monodentate HCOO- groups. The interlayer acetamidinium cations form N-HO H-bonds with the anionic layers to support the 3D structure. As the directions of most vibrations of the interlayer atoms are approximately along the a-axis, the two materials exhibit nearly zero thermal expansion (a few (MK)-1) along the b-direction perpendicularly to the layers and positive thermal expansion along the a- (∼40 (MK)-1) and c- (∼20 (MK)-1) axes parallel to the layers. They are both weak ferromagnets, and the Néel temperatures are 6.0 K and 17.0 K for M = Co and Ni, respectively. The Co compound exhibited high spontaneous magnetization of 444 cm3 G mol-1 under a field of 10 Oe and an unusually low coercive field of 38 Oe at 2 K. IR spectroscopic, thermal and dielectric properties were investigated.

[Pollution Characteristics and Emission Coefficient of Volatile Organic Compounds from Auto/motorcycle Parts & Accessories Manufacturing in Zhejiang Province].

The status of volatile organic compound (VOC) treatment in auto/motorcycle parts & accessories manufacturing in Zhejiang province was analyzed based on data from a survey investigating 70 concerned enterprises conducted in 2015. The pollution characteristics were further explored and the emission coefficient of VOCs released from this industry was preliminarily calculated by analyzing the survey data of 56 of the typical enterprises that had been screened further. The results showed that about two thirds of the enterprises had been equipped with collection and treatment facilities, but most of those facilities were running abnormally. Solvent-based materials were used commonly in this industry, and the main VOCs pollutants were xylene, butyl acetate, cyclohexanone, acetic ether, and toluene. The VOCs emission coefficient of auto/motorcycle parts & accessories manufacturing in Zhejiang was 414 g·(thousand yuan)-1, whereas the emission coefficient of the enterprises producing parts & accessories for only auto was 294 g·(thousand yuan)-1. As for the the enterprises producing parts & accessories for only motorcycle and for both auto and motorcycle, the emission coefficient reached 715 g·(thousand yuan)-1.

Alkylamine-Templated Niccolite Frameworks of [GaIIIMII(HCOO)6]- (M = Fe, Ni): Structure, Magnetism, and Dielectricity.

The five heterometallic formate frameworks [EtA][GaIIIFeII(HCOO)6] (1; EtA = CH3CH2NH3+), [DMA][GaIIIFeII(HCOO)6] (2; DMA = (CH3)2NH2+), [DEtA][GaIIIFeII(HCOO)6] (3; DEtA = (CH3CH2)2NH2+), [MA][GaIIINiII(HCOO)6] (4; MA = CH3NH3+), and [DMA][GaIIINiII(HCOO)6] (5) were synthesized through solvothermal methods. Complexes 1-5 are isotructural, and all crystallize in the trigonal P3̅1 c space group. Each metal center is 6-connected, with each HCOO- bridging ligand in an anti-anti mode to build a three-dimensional niccolite-like architecture. All of the complexes exhibit weak ferromagnetism at low temperature. A variable-temperature (VT) dielectric study indicates that the dielectric anomaly is induced by the freezing of motions from the protonated amines during the freezing process.

A Series of Bimetallic Ammonium AlNa Formates.

A series of AlNa bimetallic ammonium metal formate frameworks (AlNa AMFFs) have been prepared by employing various ammoniums from NH4+ to large linear polyammoniums. The series consists of six perovskites of (412 ⋅63 ) topology for mono-ammoniums, two chiral (49 ⋅66 ) frameworks incorporating polyethylene ammoniums, two niccolites with (412 ⋅63 )(49 ⋅66 ) topology containing diammoniums, and two layered compounds made of 2D (4,4) AlNa formate sheets intercalated by small diammoniums. The first ten compounds present the structural hierarchy of (412 ⋅63 )m (49 ⋅66 )n framework topologies for (m, n)=(1, 0), (0, 1), and (1, 1), respectively, in parallel to the homometallic AMFFs for divalent metals. The symmetry lowering, asymmetric formate bridges, and different hydrogen-bonding strengths appeared in the bimetallic structures owing to the different charge and size of Al3+ and Na+ seemingly inhibits the occurrence of phase transitions for more than half the AlNa AMFFs within the series, and the bimetallic members undergoing phase transitions show different transition behaviors and dielectric properties compared with the homometallic analogs. Anisotropic/negative/zero thermal expansions of the materials could be rationally attributed to the librational motion, or flip movement between different sites, of the ammonium cations, and the coupled change of AlNa formate frameworks. The thermal and IR spectroscopic properties have also been investigated.

Mutant Exon1 Huntingtin Aggregation is Regulated by T3 Phosphorylation-Induced Structural Changes and Crosstalk between T3 Phosphorylation and Acetylation at K6.

Herein, we used protein semisynthesis to investigate, for the first time, the effect of lysine acetylation and phosphorylation, as well as the crosstalk between these modifications on the structure and aggregation of mutant huntingtin exon1 (Httex1). Our results demonstrate that phosphorylation at T3 stabilizes the α-helical conformation of the N-terminal 17 amino acids (Nt17) and significantly inhibits the aggregation of mutant Httex1. Acetylation of single lysine residues, K6, K9 or K15, had no effect on Httex1 aggregation. Interestingly, acetylation at K6, but not at K9 or K15, reversed the inhibitory effect of T3 phosphorylation. Together, our results provide novel insight into the role of Nt17 post-translational modifications in regulating the structure and aggregation of Httex1 and suggest that its aggregation and possibly its function(s) are controlled by regulatory mechanisms involving crosstalk between different PTMs.

Two Magnetic Switching Complexes Based on the Fe(II) Ion.

Two neutral mononuclear iron(II) complexes with different spin-crossover (SCO) properties, Fe(L1)2(SCN)2 (1) and Fe(L2)2(SCN)2 (2) (L1 = 2-(thiophen-3-yl)-1H-imidazo[4,5-f][1,10]phenanthroline and L2 = 2-(thiophen-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline), were solvothermally synthesized. With the different substituted position in 1,10-phenanthroline derivatives, 1 exhibits gradual SCO around room temperature with T1/2 = 280 K, while 2 displays abrupt SCO with 10 K hysteresis at T1/2↓ = 210 K and T1/2↑ = 220 K.

Perovskite-Like Polar Lanthanide Formate Frameworks of [NH2NH3][Ln(HCOO)4] (Ln = Tb-Lu and Y): Synthesis, Structures, Magnetism, and Anisotropic Thermal Expansion.

A series of isostructural hydrazinium lanthanide (Ln) formate framework compounds of [NH2NH3][Ln(HCOO)4] for Ln3+ ions from Tb3+ to Lu3+ and Y3+ have been successfully prepared by utilizing NH2NH3+. The compounds crystallize in orthorhombic polar space group Pca21, with cell parameters at 180 K of a = 18.2526(7)-18.1048(5) Å, b = 6.5815(2)-6.5261(2) Å, c = 7.6362(3)-7.5044(2) Å, and V = 917.33(6)-886.67(4) Å3, showing the effect of lanthanide contraction. The compounds possess polar perovskite-like structures incorporating the hydrazinium cations in the cavities of the NaCl-like framework, in which the Ln3+ ions in a bicapped trigonal prism are connected by anti-anti and syn-anti formate groups. The N-H···Oformate hydrogen-bonding interactions are between the hydrazinium cations and the anionic framework. One anti-anti formate group is frustrated by the competitive N-H···Oformate hydrogen-bonding interactions. It thus twists or flips upon warming, resulting in large anisotropic thermal expansion and negative thermal expansion below 180 K. A comparison with the transition metal and magnesium analogues revealed that the structural compactness, tighter binding of the hydrazinium cation by the framework, and symmetrically better match between the framework and ammonium cation for Ln compounds could inhibit the occurrence of phase transition in the series. The IR spectroscopic, thermal, and magnetic properties are investigated.

Weak Ligand-Field Effect from Ancillary Ligands on Enhancing Single-Ion Magnet Performance.

A series of bis-pentamethylcyclopentadienyl-supported Dy complexes containing different ancillary ligands were synthesized and characterized. Magnetic studies showed that 1 Dy [Cp*2 DyCl(THF)], 1 Dy' [Cp*2 DyCl2 K(THF)]n , 2 Dy [Cp*2 DyBr(THF)], 3 Dy [Cp*2 DyI(THF)] and 4 Dy [Cp*2 DyTp] (Tp=hydrotris(1-pyrazolyl)borate) were single-ion magnets (SIMs). The 1D dysprosium chain 1 Dy' exhibited a hysteresis at up to 5 K. Furthermore, 3 Dy featured the highest energy barrier (419 cm(-1) ) among the complexes. The effects of ancillary ligands on single-ion magnetic properties were studied by experimental, ab initio calculations and electrostatic analysis methods in detail. These results demonstrated that the QTM rate was strongly dependent on the ancillary ligands and that a weak equatorial ligand field could be beneficial for constructing Dy-SIMs.

Dinuclear dysprosium SMMs bridged by a neutral bipyrimidine ligand: two crystal systems that depend on different lattice solvents lead to a distinct slow relaxation behaviour.

Two dinuclear dysprosium complexes with the Dy(iii) ions bridged by the neutral bipyrimidine (BPYM) ligand were synthesized and magnetically characterized. They crystallized in a monoclinic and triclinic crystal system, respectively, with almost the same structural core, only differing in the lattice solvent molecules. Alternating current (ac) susceptibility measurements revealed that they exhibit significant slow relaxation of magnetization until 25 K in the absence of a dc field. The single and double relaxation processes were assigned to one and two types of Dy(iii) environments in the two dimmers, respectively, with barriers of 266 and 345 K under zero field conditions. The magnetic hysteresis loops of 1 and 2 were both observed up to 2.5 K.

An Intein-based Strategy for the Production of Tag-free Huntingtin Exon 1 Proteins Enables New Insights into the Polyglutamine Dependence of Httex1 Aggregation and Fibril Formation.

The first exon of the Huntingtin protein (Httex1) is one of the most actively studied Htt fragments because its overexpression in R6/2 transgenic mice has been shown to recapitulate several key features of Huntington disease. However, the majority of biophysical studies of Httex1 are based on assessing the structure and aggregation of fusion constructs where Httex1 is fused to large proteins, such as glutathione S-transferase, maltose-binding protein, or thioredoxin, or released in solution upon in situ cleavage of these proteins. Herein, we report an intein-based strategy that allows, for the first time, the rapid and efficient production of native tag-free Httex1 with polyQ repeats ranging from 7Q to 49Q. Aggregation studies on these proteins enabled us to identify interesting polyQ-length-dependent effects on Httex1 oligomer and fibril formation that were previously not observed using Httex1 fusion proteins or Httex1 proteins produced by in situ cleavage of fusion proteins. Our studies revealed the inability of Httex1-7Q/15Q to undergo amyloid fibril formation and an inverse correlation between fibril length and polyQ repeat length, suggesting possible polyQ length-dependent differences in the structural properties of the Httex1 aggregates. Altogether, our findings underscore the importance of working with tag-free Httex1 proteins and indicate that model systems based on non-native Httex1 sequences may not accurately reproduce the effect of polyQ repeat length and solution conditions on Httex1 aggregation kinetics and structural properties.

A Variety of Phase-Transition Behaviors in a Niccolite Series of [NH3 (CH2 )4 NH3 ][M(HCOO)3 ]2.

A niccolite series of [bnH2 (2+) ][M(HCOO)3 ]2 (bnH2 (2+) =1,4-butyldiammonium) shows four kinds of metal-dependent phase transitions, from high temperature para-electric phases to low-temperature ferro-, antiferro-, glass-like, and para-electric phases. The conformational flexibility of bnH2 (2+) and the different size, mass, and bonding character of the metal ion lead to various disorder-order transitions of bnH2 (2+) in the lattice and relevant framework modulations, thus different phase transitions and dielectric responses. The magnetic members display a coexistence or combination of electric and magnetic orderings in the low-temperature region.

Can Non-Kramers Tm(III) Mononuclear Molecules be Single-Molecule Magnets (SMMs)?

In recent years, plentiful lanthanide-based (Tb(III) , Dy(III) , and Er(III) ) single-molecule magnets (SMMs) were studied, while examples of other lanthanides, for example, Tm(III) are still unknown. Herein, for the first time, we show that by rationally manipulating the coordination sphere, two thulium compounds, 1[(Tp)Tm(COT)] and 2[(Tp*)Tm(COT)] (Tp=hydrotris(1-pyrazolyl)borate; COT=cyclooctatetraenide; Tp*=hydrotris(3,5-dimethyl-1-pyrazolyl)borate), can adopt the structure of non-Kramers SMMs and exhibit their behaviors. Dynamic magnetic studies indicated that both compounds showed slow magnetic relaxation under dc field and a relatively high effective energy barrier (111 K for 1, 46 K for 2). Magnetic diluted 1 a[(Tp)Tm0.05 Y0.95 (COT)] and 2 a[(Tp*)Tm0.05 Y0.95 (COT)] even exhibited magnetic relaxation under zero dc field. Relativistic ab initio calculations combined with single-crystal angular-resolved magnetometry measurements revealed the strong easy axis anisotropy and nearly degenerated ground doublet states. The comparison of 1 and 2 highlights the importance of local symmetry for obtaining Tm SMMs.