Certification of New Selenium-Enriched Yeast and Supplement Reference Materials for Selenomethionine Using Two Independent Measurement Strategies.

Selenium-enriched yeast possesses the unique ability of transforming chemical selenium, such as sodium selenite, into a biologically active form, which mitigates its toxic effects on the human body. The transformation product of this process, selenomethionine, can be safely and effectively absorbed and utilized by the human body; hence, it has been spiked into a selenium-enriched supplement. This study employs two distinct measurement strategies to determine the selenomethionine content in two candidate reference materials, a selenium-enriched yeast powder and supplement, using both organic and inorganic mass spectrometry. The concentrations of selenomethionine in the selenium-enriched yeast were determined using HPLC-ICP-MS and HPLC- ESI-MS/MS, with mass fractions measured at 718 mg SeMet kg-1 and 715 mg SeMet kg-1, respectively. Notably, both methods yielded consistent results for the selenium supplement, with a selenomethionine mass fraction of 59 mg SeMet kg-1. Ultimately, the certified values of these candidate reference materials were determined as 716 mg kg-1 and 59 mg SeMet kg-1 with expanded uncertainties of 36 mg SeMet kg-1 (k = 2) and 5 mg SeMet kg-1 (k = 2), respectively. The development of these candidate reference materials serves as a valuable reference for diverse methods aiming to determine the value of organic selenium speciation in complex food substrates.

A century-long record of polycyclic aromatic hydrocarbon deposition in the Old Yellow River Estuary, China.

Polycyclic aromatic hydrocarbons (PAHs) are potential geochemical indicators for assessing the impact of human activities and can be used to reconstruct historical human activities. This study collected a 108 cm sediment core from the 5th lobe of the Yellow River Delta for the first time and analyzed the historical distribution characteristics of PAHs in this area. The results showed that the sedimentation history of the core was from 1908 to 2014. The average value of PAHs was 28.93 ng/g. Biomass and coal combustion sources were the main sources of PAHs in the low-value areas, while oil spill sources were the main sources in the significantly higher PAHs areas in the 1960s, mid-1980s, late 1990s, and late 2010s, which was consistent with the development history of Shengli Oilfield. Compared with global estuaries, the historical industrial activity intensity in this area was weaker.

Niche differentiation and influencing factors of nitrite oxidation bacteria Nitrospira in sediments of the Luan River estuary in China.

In the estuarine sediment, the nitrite oxidation process mediated by bacteria significantly influences nitrification. Nitrospira is the most widely distributed nitrite-oxidizing bacteria (NOB) and can adapt to various environments. In this study, the Nitrospira-specific primer nxrB 169F-638R was used to analyze the microbial communities in the sediments of low-, middle-, and high-level zones in the Luan River estuary. The structure of the microbial community and its response to environmental factors were also assessed. The abundance and diversity of Nitrospira were the highest in the low-level zone and lowest in the high-level zone. Lineage II and lineage IV were the dominant Nitrospira at 43.58% and 32.09%, respectively. The distribution pattern of Nitrospira was also affected by complex environmental factors, such as the concentration of NH4+, Fe, and Cu cations. This study provides novel insights into the niche differentiation and adaptation strategies of Nitrospira in an estuarine sediment environment and will help to facilitate single-step nitrification.

Cocrystallization of Two Negatively Charged Dimercaptomaleonitrile-Stabilized Silver Nanoclusters.

Studies on the assembly of atomically precise metal nanoclusters (NCs) are of great significance in the nanomaterial field, which has attracted increasing interest in the last few decades. Herein, we report the cocrystallization of two negatively charged atom-precise silver nanoclusters, the octahedral [Ag62(MNT)24(TPP)6]8- (Ag62) and the truncated-tetrahedral [Ag22(MNT)12(TPP)4]4- (Ag22) in a 1:2 ratio (MNT2- = dimercaptomaleonitrile, TPP = triphenylphosphine). As far as we know, a cocrystal containing two negatively charged NCs has seldom been reported. Single-crystal structure determinations reveal that the component Ag22 and Ag62 NCs both adopt core-shell structures. In addition, the component NCs were separately obtained by adjusting the synthetic conditions. This work enriches the structural diversity of silver NCs and extends the family of cluster-based cocrystals.

Stepwise Amplification of Circularly Polarized Luminescence in Chiral Metal Cluster Ensembles.

Chiral metal-organic frameworks (MOFs) are usually endowed by chiral linkers and/or guests. The strategy using chiral secondary building units in MOFs for solving the trade-off of circularly polarized luminescence (CPL)-active materials, high photoluminescence quantum yields (PLQYs) and high dissymmetry factors (|glum |) has not been demonstrated. This work directionally assembles predesigned chiral silver clusters with ACQ linkers through reticular chemistry. The nanoscale chirality of the cluster transmits through MOF's framework, where the linkers are arranged in a quasi-parallel manner and are efficiently isolated and rigidified. Consequently, this backbone of chiral cluster-based MOFs demonstrates superb CPL, high PLQYs of 50.3%, and |glum | of 1.2 × 10-2 . Crystallographic analyses and DFT calculations show the quasi-parallel arrangement manners of emitting linkers leading to a large angle between the electric and magnetic transition dipole moments, boosting CPL response. As compared, an ion-pair-direct assembly without interactions between linkers induces one-ninth |glum | and one-sixth PLQY values, further highlighting the merits of directional arrangement in reticular nets. In addition, a prototype CPL switching fabricated by a chiral framework is controlled through alternating ultraviolet and visible light. This work is expected to inspire the development of reticular chemistry for high-performance chiroptical materials.

Delineating and identifying risk zones of soil heavy metal pollution in an industrialized region using machine learning.

The ability to control the risk of soil heavy metal pollution is limited by the inability to accurately depict their spatial distributions and to reasonably delineate the risk zones. To overcome this limitation and develop machine learning methods, a hybrid data-driven method supported by random forest (RF) and fuzzy c-means with the aid of inverse distance weighted interpolation was proposed to delineate and further identify risk zones of soil heavy metal pollution on the basis of 577 soil samples and 12 environmental covariates. The results indicated that, compared to multiple linear regression, RF had a better prediction performance for As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn, with the corresponding R2 values of 0.86, 0.85, 0.78, 0.85, 0.84, 0.78, 0.79 and 0.76, respectively. The relative concentrations (predicted concentrations divided by risk screening values) of Cd (17.69), Cr (1.38), Hg (0.31), Pb (6.52), and Zn (8.24) were relatively high in the north central part of the study area. There were large differences in the key influencing factors and their contributions among the eight heavy metals. Overall, industrial enterprises (21.60% for As), soil pH (31.60% for Cd), and population (15.50% for Cr) were the key influencing factors for the heavy metals in soil. Four risk zones, including one high risk zone, one medium risk zone, and two low risk zones were delineated and identified based on the characteristics of the eight heavy metals and their influencing factors, and accordingly discriminated risk control strategies were developed. In the high risk zone, it will be necessary to strictly control the discharge of heavy metals from the various industrial enterprises and mines by the adoption of cleaner production practices, centralizedly treat the domestic wastes from residents, substantially reduce the irrigation of polluted river water, and positively remediate the Cd, Cr, and Ni-polluted soil.

Platonic and Archimedean solids in discrete metal-containing clusters.

Metal-containing clusters have attracted increasing attention over the past 2-3 decades. This intense interest can be attributed to the fact that these discrete metal aggregates, whose atomically precise structures are resolved by single-crystal X-ray diffraction (SCXRD), often possess intriguing geometrical features (high symmetry, aesthetically pleasing shapes and architectures) and fascinating physical properties, providing invaluable opportunities for the intersection of different disciplines including chemistry, physics, mathematical geometry and materials science. In this review, we attempt to reinterpret and connect these fascinating clusters from the perspective of Platonic and Archimedean solid characteristics, focusing on highly symmetrical and complex metal-containing (metal = Al, Ti, V, Mo, W, U, Mn, Fe, Co, Ni, Pd, Pt, Cu, Ag, Au, lanthanoids (Ln), and actinoids) high-nuclearity clusters, including metal-oxo/hydroxide/chalcogenide clusters and metal clusters (with metal-metal binding) protected by surface organic ligands, such as thiolate, phosphine, alkynyl, carbonyl and nitrogen/oxygen donor ligands. Furthermore, we present the symmetrical beauty of metal cluster structures and the geometrical similarity of different types of clusters and provide a large number of examples to show how to accurately describe the metal clusters from the perspective of highly symmetrical polyhedra. Finally, knowledge and further insights into the design and synthesis of unknown metal clusters are put forward by summarizing these "star" molecules.

Snapshots of key intermediates unveiling the growth from silver ions to Ag70 nanoclusters.

Nanoclusters (NCs) are considered as initial states of condensed matter, and unveiling their formation mechanism is of great importance for directional synthesis of nanomaterials. Here, we initiate the reaction of Ag(i) ions under weak reducing conditions. The prolonged reaction period provides a unique opportunity for revealing the five stages of the growth mechanism of 20-electron superatomic Ag70 NCs by a time-dependent mass technique, that is, aggregate (I) → reduction (II) → decomposition and recombination (III) → fusion (IV) → surface recombination and motif enrichment (V), which is different from the formation process applicable to the gold clusters. More importantly, the key intermediates, Ag14 without free electrons (0e) in the first (stage I) and Ag24 (4e) in the second (stage II), were crystallized and structurally resolved, and the later transformation rate towards Ag70 was further controlled by modulating solvents for easy identification of more intermediates. In a word, we establish a reasonable path of gradual expansion in size and electrons from Ag(i) ions to medium-sized 20e Ag70. This work provides new insights into the formation and evolution of silver NCs, and unveils the corresponding optical properties along with the process.

Stepwise structure evolution from 2D cluster-based frameworks to silver(I) clusters.

A pair of 2D chiral frameworks, R-Ag5-1 and S-Ag5-1, with orange fluorescence were successfully synthesized. They were transformed to a thermodynamically favored denser stacking, R-Ag5-3 and S-Ag5-3, accompanied by a change in the luminescence and activating the CPL signal. The capture and structural determination of the intermediates (R-Ag5-2 and S-Ag5-2) reveal that the coordination instability of Na+ ions is the main cause of this transition.

Atomically Precise Enantiopure Bimetallic Janus Clusters.

Asymmetric bimetallic Janus nanocrystals with a side-by-side interface have unique properties and important applications. However, understanding their fundamental issues, including their formation mechanism, interfacial linkage, and related properties, remains challenging, as does the preparation of enantiopure samples. Atomically precise Janus bimetal nanoclusters would unequivocally resolve these issues, yet they have not been realized. Here, based on Au and transition metals (Cu/Cd), and employing an S/P biligand strategy, we prepare and structurally resolve four Janus nanoclusters, including racemate 6e Au 8 /Cu 4 , 6e R -/ S-Au 8 /Cu 4 enantiomers, and 2e racemate Au 3 /Cd. Their interfacial linkage is unambiguously resolved at the atomic level, superatomic orbital splitting emerges, and unique molecule-like electronic transitions and chiroptical properties are present; more importantly, the dipolar distribution of bicomponents leads to a maximum dipole moment of up to 45 D, which drives the formation of 1D nanowires through self-assembly. This work provides a fundamental knowledge of intermetallic nanomaterials and an avenue for the synthesis of Janus nanoclusters.

Achiral-Core-Metal Change in Isomorphic Enantiomeric Ag12Ag32 and Au12Ag32 Clusters Triggers Circularly Polarized Phosphorescence.

Understanding how the chiral or achiral section in chiral nanostructures contributes to circularly polarized light emission (CPLE) at the atomic level is of fundamental importance. Here, we report two pairs of atomically precise enantiomers of homosilver (R/S-Ag12Ag32) and heterometal (R/S-Au12Ag32) clusters. The geometrical chirality of R/S-Ag12Ag32 arises from the chiral ligand and interface consisting of positive moieties of Ag32(R/S-PS)24. The circular dichroism of R/S-Ag12Ag32 is active, but CPLE-silent. A complete metal change from Ag12 to Au12 in the achiral core section of S2-@M12@S8 engenders isomorphous heterometal R/S-Au12Ag32, which activates CPLE. We further quantify the contributions of achiral and chiral sections and for the first time unveil that heterometal bonding (Au12-Ag32) at the linkage varies the delocalization of orbitals and proportion of achiral and chiral section in electron transition-involved orbitals, thus activating CPLE. Based on these unique atomically precise homochiral metal clusters, our work provides a new insight into the contributions of achiral and chiral sections to the origin of chiroptical response of chiral metal clusters, paving the way to advance the development of CPLE nanoparticles.

Phosphate anion-induced silver-chalcogenide cluster-based metal organic frameworks as dual-functional catalysts for detoxifying chemical warfare agent simulants.

Two porphyrinic silver-chalcogenide cluster-based MOFs were achieved using a phosphate anionic template strategy, and the highly photoactive organic building modules combined with Lewis acidic silver clusters allow both SCC-MOFs to be used as versatile catalysts for the simultaneous degradation of sulfur mustard and nerve agent simulants.

Composition-Dependent Enzyme Mimicking Activity and Radiosensitizing Effect of Bimetallic Clusters to Modulate Tumor Hypoxia for Enhanced Cancer Therapy.

Alloying is an efficient chemistry to tailor the properties of metal clusters. As a class of promising radiosensitizers, most previously reported metal clusters exhibit unitary function and cannot overcome radioresistance of hypoxic tumors. Here, atomically precise alloy clusters Pt2 M4 (M = Au, Ag, Cu) are synthesized with bright luminescence and adequate biocompatibility, and their composition-dependent enzyme mimicking activity and radiosensitizing effect is explored. Specifically, only the Pt2 Au4 cluster displays catalase-like activity, while the others do not have clusterzyme properties, and its radiosensitizing effect is the highest among all the alloy clusters tested. By taking advantage of the sustainable production of O2 via the decomposition of endogenous H2 O2 , the Pt2 Au4 cluster modulates tumor hypoxia as well as increases the efficacy of radiotherapy. This work thus advances the cluster alloying strategy to produce multifunctional therapeutic agents for improving hypoxic tumor therapy.

Arsenic Release from Soil Induced by Microorganisms and Environmental Factors.

In rhizospheric soil, arsenic can be activated by both biological and abiotic reactions with plant exudates or phosphates, but little is known about the relative contributions of these two pathways. The effects of microorganisms, low-molecular-weight organic acid salts (LMWOASs), and phosphates on the migration of As in unrestored and nano zero-valent iron (nZVI)-restored soil were studied in batch experiments. The results show that As released by microbial action accounted for 17.73%, 7.04%, 92.40%, 92.55%, and 96.68% of the total As released in unrestored soil with citrate, phytate, malate, lactate, and acetate, respectively. It was only suppressed in unrestored soil with oxalate. In restored soil, As was still released in the presence of oxalate, citrate, and phytate, but the magnitude of As release was inhibited by microorganisms. The application of excess nZVI can completely inhibited As release processes induced by phosphate in the presence of microorganisms. Microbial iron reduction is a possible mechanism of arsenic release induced by microorganisms. Microorganisms and most environmental factors promoted As release in unrestored soil, but the phenomenon was suppressed in restored soil. This study helps to provide an effective strategy for reducing the secondary release of As from soils due to replanting after restoration.

Small symmetry-breaking triggering large chiroptical responses of Ag70 nanoclusters.

The origins of the chiroptical activities of inorganic nanostructures have perplexed scientists, and deracemization of high-nuclearity metal nanoclusters (NCs) remains challenging. Here, we report a single-crystal structure of Rac-Ag70 that contains enantiomeric pairs of 70-nuclearity silver clusters with 20 free valence electrons (Ag70), and each of these clusters is a doubly truncated tetrahedron with pseudo-T symmetry. A deracemization method using a chiral metal precursor not only stabilizes Ag70 in solution but also enables monitoring of the gradual enlargement of the electronic circular dichroism (CD) responses and anisotropy factor gabs. The chiral crystals of R/S-Ag70 in space group P21 containing a pseudo-T-symmetric enantiomeric NC show significant kernel-based and shell-based CD responses. The small symmetry breaking of Td symmetry arising from local distortion of Ag-S motifs and rotation of the apical Ag3 trigons results in large chiroptical responses. This work opens an avenue to construct chiral medium/large-sized NCs and nanoparticles, which are promising for asymmetric catalysis, nonlinear optics, chiral sensing, and biomedicine.

Alkynyl-Stabilized Superatomic Silver Clusters Showing Circularly Polarized Luminescence.

We report a new enantiomeric pair of superatomic silver clusters, R/S-Ag17, prepared from chiral alkynyl ligands. R-Ag17 and S-Ag17 possess C3 symmetry and emit near-infrared (NIR) light with a quantum yield (QY) of 8.0% under ambient condition as well as NIR circularly polarized luminescence (CPL) as a result of the chirality of the excited states. Both experiments and theoretical calculations indicate for the first time that the CPL originates from transitions between superatomic 1Pz (along the C3 axis) and 1S orbitals. This work opens a new avenue for CPL-active metal nanoclusters by utilizing chiral alkynyl ligands and enlightens the chirality transfer from chiral protecting ligands to superatomic states in metal clusters.

An Unprecedented Bird Nest Molybdenum(V) Cobalto-Phosphate Nanosized Wheel Constructed from the [H55 (Mo24 O48 )(Co4 O)2 Co16 (PO4 )42 (py)6 (EtOH)2 (H2 O)11 ]3- Anion.

An unprecedented bird-nest high-nuclear molybdenum(V) cobalto-phosphate nanosized wheel modified by imidazole (im) and pyridine (py), {[H55 (Mo24 O48 )(Co4 O)2 Co16 (PO4 )42 (py)6 (EtOH)2 (H2 O)11 ]- @[(Him)2 (Hpy)]}(N-Et-py)(H2 PO4 )(py)7 (EtOH)⋅12 H2 O (1), has been successfully synthesized by self-assembly. The anionic huge wheel consists of two rare {Co4 O} squares, four {Co4 } tetramers, four {Mo4 } tetramers and four {Mo2 } dimers, linked by bridging oxygen atoms and [PO4 ] groups and encloses two imidazolium cations and a protonated pyridium for charge balance. Surprisingly, 1 represents the first twisted wheel-shaped cluster with a record high-nuclear molybdenum(V) cobalto-phosphate. The delocalized electron effects of the cluster are enhanced with the help of coordinated py ligands, which endows 1 with an excellent third-order nonlinear optical (NLO) response. Additionally, 1 also shows a better photocatalytic water oxidation activity than Co(NO3 )2 with the O2 production of 205 µmol during 6 h in the absence of the [Ru(bpy)3 ]2+ photosensitizer.

Decoupling analysis between economic growth and resources environment in Central Plains Urban Agglomeration.

Once, the fast-growing economy has dependence on resources and environment, especially in Central Plains Urban Agglomeration (CPUA). Assessing the relationship between economic growth and resources and environment can be helpful in planning future region development. As there were fewer researches on the decoupling analysis in CPUA, therefore, according to the decoupling index designed by Tapio, this paper connected the resources and the environment to describe the comprehensive decoupling state of economic growth and resources environment as a whole with the latest available data in 2004-2015. The results showed that: (1) The change of environmental decoupling index had a greater impact on the comprehensive decoupling index. Economic growth has been less dependent on resources consumption and environment pollution since 2011, and the relationship between economic growth and resources environment reached strong decoupling in 2015. (2) The decoupling state was towards the direction of strong decoupling in Luoyang, Pingdingshan, Jiaozuo, Xuchang, Nanyang, and Xinyang. The economic growth was less dependent on resources consumption and the environment pollution. (3) Economic growth depended strongly on resources consumption and environment pollution in Changzhi, Jincheng, Heze, and Anyang. They had not yet achieved the strong decoupling state among economic growth, resources and the environment. Thus, the policy implementations were put forward to realize strong decoupling in CPUA.

The economic loss of health effect damages from PM2.5 pollution in the Central Plains Urban Agglomeration.

The Central Plains Urban Agglomeration is an important growth pole of China's economy, but the rapid economic growth is accompanied by serious air pollution problems. In this paper, the latest available PM2.5 monitoring data in 2015-2017 and exposure-response relationship model are used to quantitatively analyze the health effect damages due to PM2.5 pollution. The way of disease cost, adjusted human capital, and willingness to pay were adopted to estimate the economic loss of health effect damages. The results show that health effect damages of PM2.5 pollution in 2015-2017 were 11.9251 million, 11.4292 million, and 11.1012 million, respectively, accounting for 7.41%, 7.05%, and 6.94% of the total population of this area. The health effect economic loss was 97.398 billion RMB, 93.516 billion RMB, and 94.485 billion RMB, accounting for 1.73%, 1.53%, and 1.41% of the GDP. Chronic bronchitis and premature death due to PM2.5 are the main sources of health effect economic loss. Elderly people and infants are vulnerable groups of PM2.5 pollution. Affected by economic growth level, population density, and economic structure, Heze, Zhengzhou, Handan, and Liaocheng were greatly affected by PM2.5 pollution, and their health effect damages was larger. The health effect damages and health effect economic loss due to PM2.5 pollution in this area show a downward trend, indicating that air pollution reduction measures have played a positive role. However, the whole effect is still large. According to the results, this paper puts forward the policies.

A Series Three-Dimensional Ln4Cr4 (Ln = Gd, Tb, Er) Heterometallic Cluster-Based Coordination Polymers Containing Interesting Nanotubes Exhibiting High Magnetic Entropy.

A series of novel 3D 3d-4f heterometallic cluster-based coordination polymers, [Ln4Cr4(µ3-O)4(µ4-O)4(NA)8(H2O)12]·xH2O (Ln = 1-Gd, 2-Tb, 3-Er; HNA = nicotinic acid; x = 13 (1-Gd), 11.33 (2-Tb), 15 (3-Er)), have been successfully synthesized by hydrothermal method using nicotinic acid as bridging ligand. The single-crystal X-ray diffraction (SCXRD) analysis indicated that the basic unit of Ln4Cr4 shows a butterfly-shaped structure. Furthermore, each Ln4Cr4 cluster connects with other four Ln4Cr4 clusters by bridging NA- ligands to form a 3D structure containing interesting 1D honeycomb-shaped coordination nanotubes. The variable temperature magnetic susceptibility measurements of compound 1 revealed that the existence of antiferromagnetic (AF) coupling between the metal ions in the Gd4Cr4 clusters. Field-dependent isothermal magnetization studies displayed that the magnetic entropy change (-ΔSm) value of 1-Gd reached 22.05 J K-1 kg-1.