BaCu, a Two-Dimensional Electride with Cu Anions.

The electron-rich characteristic and low work function endow electrides with excellent performance in (opto)electronics and catalytic applications; these two features are closely related to the structural topology, constituents, and valence electron concentration of electrides. However, the synthesized electrides, especially two-dimensional (2D) electrides, are limited to specific structural prototypes and anionic p-block elements. Here we synthesize and identify a distinct 2D electride of BaCu with delocalized anionic electrons confined to the interlayer spaces of the BaCu framework. The bonding between Cu and Ba atoms exhibits ionic characteristics, and the adjacent Cu anions form a planar honeycomb structure with metallic Cu-Cu bonding. The negatively charged Cu ions are revealed by the theoretical calculations and experimental X-ray absorption near-edge structure. Physical property measurements reveal that BaCu electride has a high electronic conductivity (ρ = 3.20 µΩ cm) and a low work function (2.5 eV), attributed to the metallic Cu-Cu bonding and delocalized anionic electrons. In contrast to typical ionic 2D electrides with p-block anions, density functional theory calculations find that the orbital hybridization between the delocalized anionic electrons and BaCu framework leads to unique isotropic physical properties, such as mechanical properties, and work function. The freestanding BaCu monolayer with half-metal conductivity exhibits low exfoliation energy (0.84 J/m2) and high mechanical/thermal stability, suggesting the potential to achieve low-dimensional BaCu from the bulk. Our results expand the space for the structure and attributes of 2D electrides, facilitating the discovery and potential application of novel 2D electrides with transition metal anions.

Folic acid attenuates the effects of amyloid ß oligomers on DNA methylation in neuronal cells.

PURPOSE: Alzheimer's disease (AD) is a highly prevalent type of dementia. The epigenetic mechanism of gene methylation provides a putative link between nutrition, one-carbon metabolism, and disease progression because folate deficiency may cause hypomethylation of promoter regions in AD-relevant genes. We hypothesized that folic acid supplementation may protect neuron cells from amyloid ß (Aß) oligomer-induced toxicity by modulating DNA methylation of APP and PS1 in AD models. METHODS: Primary hippocampal neuronal cells and hippocampal HT-22 cells were incubated for 24 h with a combination of folic acid and either Aß oligomers or vehicle and were then incubated for 72 h with various concentrations of folic acid. AD transgenic mice were fed either folate-deficient or control diets and gavaged daily with various doses of folic acid (0 or 600 µg/kg). DNA methyltransferase (DNMT) activity, cell viability, methylation potential of cells, APP and PS1 expression, and the methylation of the respective promoters were determined. RESULTS: Aß oligomers lowered DNMT activity, increased PS1 and APP expression, and decreased cell viability. Folic acid dose-dependently stimulated methylation potential and DNMT activity, altered PS1 and APP promoter methylation, decreased PS1 and APP expression, and partially preserved cell viability. Folic acid increased PS1 and APP promoter methylation in AD transgenic mice. CONCLUSION: These results suggest a mechanism by which folic acid may prevent Aß oligomer-induced neuronal toxicity.

Folic Acid Inhibits Amyloid ß-Peptide Production through Modulating DNA Methyltransferase Activity in N2a-APP Cells.

Alzheimer's disease (AD) is a common neurodegenerative disease resulting in progressive dementia, and is a principal cause of dementia among older adults. Folate acts through one-carbon metabolism to support the methylation of multiple substrates. We hypothesized that folic acid supplementation modulates DNA methyltransferase (DNMT) activity and may alter amyloid ß-peptide (Aß) production in AD. Mouse Neuro-2a cells expressing human APP695 were incubated with folic acid (2.8-40 µmol/L), and with or without zebularine (the DNMT inhibitor). DNMT activity, cell viability, Aß and DNMTs expression were then examined. The results showed that folic acid stimulated DNMT gene and protein expression, and DNMT activity. Furthermore, folic acid decreased Aß protein production, whereas inhibition of DNMT activity by zebularine increased Aß production. The results indicate that folic acid induces methylation potential-dependent DNMT enzymes, thereby attenuating Aß production.

[Measurement of S-adenosylmethionine and S-adenosylhomocysteine in mice liver with high performance liquid chromatography].

OBJECTIVE: To develop a method for determination of S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) simultaneously in mice liver by reversed-phase high performance liquid chromatography (HPLC). METHODS: Mice livers were weighed, emulsified quickly by handheld homogenate, four times the volume of 0.6 mol/L HCLO4 added for ultrasonic, and the hydrolysate was adjusted to centrifuged and filtrated with a membrane. The supernatants were separatedonVenusil MP-C18 column (250 mm x 4.6 mm, 5 µm) at 30 °C with a mobile phase of 50 mmol/L NaH2PO4, 10 mmol/L C7H15NaO3S and methanol, a flow rate of 1.0 ml/min and UV detection at 254 nm. RESULTS: The SAM and SAH in the corresponding concentration range showed a good linear relation with its peak area, correlation coefficient ( r > 0. 9990 ) , recovery was 92.20%-101.38%, RSD was 2.88%-6.78%. The average within-day precision of SAM and SAH was 4.14% and 3.71%, and the average day to day precision was 7.51% and 9.54%. The content of SAM and SAH in mice liver was 3.14-6.09 mg/L (31.44-60.98 nmol/g wet weight) and 1.29-3.10 mg/L (13.38-32.17 nmol/g wet weight) respectively. CONCLUSION: The validated method is simple, rapid accurate and reliable to the determination of SAM and SAH in mice liver.

Relationship between blood levels of methyl donor and folate and mild cognitive impairment in Chinese patients with type 2 diabetes: a case-control study.

Type 2 diabetes is a risk factor for Alzheimer's disease and mild cognitive impairment. Folate insufficiency fosters a decline in the sole methyl donor, S-adenosylmethionine, and decreases methylation potential, which is associated with Alzheimer's disease in non-diabetic patients. However, little is known in diabetic patients. We analyzed plasma levels of S-adenosylmethionine, S-adenosylhomocysteine and serum level of folate in 100 elderly type 2 diabetic patients with and without mild cognitive impairment. S-adenosylmethionine/S-adenosylhomocysteine ratio was used to reflect the methylation potential. Patients with mild cognitive impairment had significantly lower levels of S-adenosylmethionine, folate and S-adenosylmethionine/S-adenosylhomocysteineratios. Furthermore, logistic regression analysis indicated the plasma S-adenosylmethionine, S-adenosylmethionine/S-adenosylhomocysteine ratio and serum folate (OR, 0.96, 0.698, 0.72, respectively; p<0.05) were negatively associated with risk of mild cognitive impairment, even after adjusting for related covariates. In addition, folate level was positively correlated with S-adenosylmethionine and the S-adenosylmethionine/S-adenosylhomocysteine ratio (r = 0.38, 0.46, respectively; p<0.05) among patients within the middle tertile of folate levels (6.3-9.1 µg/L). These findings indicate mild cognitive impairment is associated with lower levels of S-adenosylmethionine, folate and weakened methylation potential; plasma S-adenosylmethionine and methylation potential may be predicted by serum folate within a suitable range of folate concentrations in diabetic patients.

[Measurement of S-adenosylmethionine and S-adenosylhomocysteine in plasma with high performance liquid chromatography].

OBJECTIVE: To develop a method for determination of S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) simultaneously in plasma by reversed-phase high performance liquid chromatography (HPLC). METHODS: The plasma were hydrolyzed with trichloroacetic acid 400 g/L, then the hydrolysate was adjusted to centrifuged and filtrated with a 0.45 microm membrane. The supernatants were separated on Venusil MP-C18 column (4.6 mm x 250 mm, 5 microm) at 30 degrees C with a mobile phase of 50 mmol/L NaH2PO4 (pH 4.38), C7 H15, NaO3 S and methanol, a flow rate of 1.0 ml/ min, and UV detection at 254nm. RESULTS: The SAM and SAH in the corresponding concentration range showed a good linear relation with its peak area, correlation coefficient r > 0.9999, recovery was 94.14% - 102.44%, RSD was 1.00% - 8.10%. The content of SAM and SAH in plasma of healthy people was 0.032 - 0.080 mg/L and 0.004 - 0.010 mg/L respectively. CONCLUSION: The validated method is simple, rapid accurate and reliable to the determination of SAM and SAH in plasma.

A Multidimensional Topotactic Host Composite Anode Toward Transparent Flexible Potassium-Ion Microcapacitors.

Transparent flexible supercapacitors (TFSCs) are a tantalizing power supplier for future transparent flexible electronics. However, their energy density is far behind a practical level while maintaining high transparency. We report here a transparent flexible potassium-ion microcapacitor, and its high energy density (15.5 µWh cm-2) roots in the battery-supercapacitor hybrid storage mechanism and much enlarged working voltage (3 V), outperforming the state-of-the-art TFSC, which is generally based on an aqueous electrolyte and an asymmetric pseudocapacitive mechanism. From an electrode material perspective, a multidimensional topotactic host composite anode is designed in which the component not only performs energy storage by synchronous and reversible uptake of potassium ions and electrons into its host structure, but also mutually compensates individual weakness in functional and structural aspects, efficiently constructing a three-dimensional potassium-ion diffusion and electron transport system. This conceptual exhibition provides design principles at material and device levels for high-performance TFSCs.

Structure Determination, Mechanical Properties, Thermal Stability of Co2MoB4 and Fe2MoB4.

The precise determination of atomic position of materials is critical for understanding the relationship between structure and properties, especially for compounds with light elements of boron and single or multiple transition metals. In this work, the single crystal X-ray diffraction is employed to analyze the atomic positions of Co2MoB4 and Fe2MoB4 with a Ta3B4-type structure, and it is found that the lengths of B-B bonds connecting the two zig-zag boron chains are 1.86 Å and 1.87 Å, but previously unreported 1.4 Å. Co and Fe atoms occupy the same crystallographic position in lattice for the doped samples and the valence is close to the metal itself, and Co/Fe K-edge X-ray Absorption Fine Structure(XAFS) spectra of borides with different ratios of Co to Fe are collected to detect the local environment and chemical valence of Co and Fe. Vickers hardness and nano indentation measurements are performed, together with the Density Functional Theory (DFT) calculations. Finally, Co2MoB4 possess better thermal stability than Fe2MoB4 evaluated by Thermogravimetric Differential Thermal Analysis (TG-DTA) results.