Metformin induces myeloma cells necrosis and apoptosis and it is considered for therapeutic use.

Accumulating evidence, especially in solid tumor, indicated that metformin possessed the potential ability in the proliferation of cancer cells. However, its effects on myeloma cells were relatively rarely clarified. To evaluate the anti-cancer effects of metformin against dexamethasone-resistant and -sensitive myeloma cells. The effects of metformin on myeloma cell lines, including dexamethasone-resistant U266, H929, RPMI 8226 and dexamethasone-sensitive MM.1s, were investigated using the cell counting kit-8 assay for cell proliferation. Apoptosis, necrosis, cell cycle arrest, and cell death mechanisms were explored via flow cytometry (FCM) and Western blot. In addition, the anti-myeloma activity was evaluated in vivo via non-obese diabetic/severe combined immunodeficiency xenograft mouse models. Metformin inhibited proliferation in a dose and time-dependent manner in all the cell lines, while dexamethasone only affected the viability of MM1.s cells. The FCM detection displayed that metformin induced apoptosis in H929, RPMI8226 and MM.1s cells, while for U266 cells, it induced necrosis with Annexin V-/Propidium iodide+. The cell cycle assays showed that metformin arrested G0/G1 phase of H929 and MM.1s cells, or G2/M phase of RPMI8226 cells, but showed no effect on U226 cells. Western blotting analyses demonstrated that the apoptosis-related protein of cleaved caspase 3 was activated; the expressions of Mcl-1, IGF-1R, PI3K, pAKT, and pmTOR proteins were inhibited by metformin in H929, RPMI8226, and MM.1s cells. The necrosis-related protein of iNOS increased in U266 cells while metformin treated. In vivo assay indicated metformin decreased U266 and H929 growth in bone marrow, and thus prolonged mice survival. These data suggested that metformin inhibited the proliferation of myeloma cells via inducing necrosis and apoptosis. This finding indicated that metformin may be served as a potent adjuvant in treating multiple myeloma.

Electrocatalytic water oxidation enabling the highly selective oxidation of styrene to benzaldehyde.

An electrooxidation strategy mediated by reactive oxygen species is proposed to realize the transformation of styrene to benzaldehyde on a Pt anode, with a high selectivity of ca. 89% and faradaic efficiency of 28.8%. Isotopic labelling, electron paramagnetic resonance and radical scavenging experiments revealed that OH˙ and O2-˙ species, formed in situ via anodic water oxidation, play a crucial role in the selective formation of benzaldehyde.

Electrochemical Reduction of CO2 to HCOOH over Copper Catalysts.

Although great progress has been made in the field of electrochemical CO2 reduction reaction (eCO2RR), inducing product selectivity is still difficult. We herein report that a thiocyanate ion (SCN-) switched the product selectivity of copper catalysts for eCO2RR in an H-cell. A cuprous thiocyanate-derived Cu catalyst was found to exhibit excellent HCOOH selectivity (faradaic efficiency = 70-88%) over a wide potential range (-0.66 to -0.95 V vs RHE). Furthermore, it was revealed that the formation of CO and C2H4 over commercial copper electrodes could be dramatically suppressed with the presence of SCN-, switching to HCOOH. Density functional theory calculations disclosed that SCN- made the formation of HCOO* easier than COOH* on Cu (211), facilitating the HCOOH generation. Our results provide a new insight into eCO2RR and will be helpful in the development of cheap electrocatalysts for specific utilization.

Catalytic Asymmetric Three-Component Reaction of 2-Alkynylbenzaldehydes, Amines, and Dimethylphosphonate.

An efficient enantioselective synthesis of cyclic α-aminophosphonates via multicomponent reactions of 2-alkynylbenzaldehydes, amines, and dimethylphosphonate has been developed with the use of a chiral silver spirocyclic phosphate as the catalyst. This protocol provides straightforward access to a series of chiral C1-phosphonylated 1,2-dihydroisoquinoline derivatives with high yields (up to 99%) and high enantioselectivities (up to 94% ee) for a broad substrate scope. The products could be further transformed into densely functionalized compounds and corresponding α-aminophosphonic acids.

Controllable synthesis of titanium nitride nanotubes by coaxial electrospinning and their application as a durable support for oxygen reduction reaction electrocatalysts.

Chemical and electrochemical corrosion of a support limits the corresponding catalyst's performance and lifetime. In this paper, uniform TiN nanotubes are synthesized via coaxial-electrospinning, thermal oxidation and nitridation. The average diameter of nanotubes can be facilely controlled by tuning the parameters of coaxial electrospinning. The TiN nanotubes are modified further with Pt nanoparticles as Pt/TiN NT electrocatalysts. After accelerated durability tests, the electrochemical surface area (ECSA) and mass activity of the Pt/TiN decrease by only 6% and 14% respectively, while those of the Pt/C decrease by 44% and 46.2% respectively. The enhanced activity is attributed to the strong interaction between the Pt nanoparticles and the TiN support, which is confirmed by the X-ray dispersive spectra of Pt 4f.

Enantioselective 1,3-Dipolar Cycloaddition of Methyleneindolinones with α-Diazomethylphosphonate to Access Chiral Spiro-phosphonylpyrazoline-oxindoles Catalyzed by Tertiary Amine Thiourea and 1,5-Diazabicyclo[4.3.0]non-5-ene.

A methodology to access chiral 3,3'-spiro-phosphonylpyrazoline oxindoles via an asymmetric 1,3-dipolar cycloaddition reaction of substituted methyleneindolinones with α-diazomethylphosphonate in the catalysis of tertiary amine thiourea and 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) has been established. This method exhibits high functional group compatibility, where a wide range of methyleneindolinones with various substituents and heterocyclic rings are accommodated by this reaction. The resulting chiral 3,3'-spiro-phosphonylpyrazoline oxindoles can be further transformed into spiro-phosphonylcyclopropane oxindoles by ring contraction.

Research on the Terahertz Absorption Spectra of Histidine Enantiomer (L) and its Racemic Compound (DL).

Terahertz time-domain spectroscopy (THz-TDS) is used to investigate the absorption spectra of polycrystalline L- and DL-histidine in the frequency range of 10-100 cm-1. The spectra exhibit distinct differences in peak frequencies between the enantiomer (L-histidine) and racemic compound (DL-histidine). The observed spectral differences are attributed to the intermolecular interactions. With the density function theory (DFT) method, the frequencies of vibrational modes of L-histidine and DL-histidine in the THz range are calculated and well assigned according to the measured spectra. The origin of the observed vibrational modes is found to be non-localized and of a collective (phonon-like) nature, which points to the lattice and skeleton vibrations mediated by the hydrogen bond. Furthermore, we propose and demonstrate a method for determining the composition ratio of histidine mixtures based on the THz absorption spectra.

Plasmonic Pd Nanoparticle- and Plasmonic Pd Nanorod-Decorated BiVO4 Electrodes with Enhanced Photoelectrochemical Water Splitting Efficiency Across Visible-NIR Region.

The photoelectrochemical (PEC) water splitting performance of BiVO4 is partially hindered by insufficient photoresponse in the spectral region with energy below the band gap. Here, we demonstrate that the PEC water splitting efficiency of BiVO4 electrodes can be effectively enhanced by decorating Pd nanoparticles (NPs) and nanorods (NRs). The results indicate that the Pd NPs and NRs with different surface plasmon resonance (SPR) features delivered an enhanced PEC water splitting performance in the visible and near-infrared (NIR) regions, respectively. Considering that there is barely no absorption overlap between Pd nanostructures and BiVO4 and the finite-difference time domain (FDTD) simulation indicating there are substantial energetic hot electrons in the vicinity of Pd nanostructures, the enhanced PEC performance of Pd NP-decorated BiVO4 and Pd NR-decorated BiVO4 could both benefit from the hot electron injection mechanism instead of the plasmon resonance energy transfer process. Moreover, a combination of Pd NPs and NRs decorated on the BiVO4 electrodes leads to a broad-band enhancement across visible-NIR region.

Structural transformation of carbon-supported Pt3Cr nanoparticles from a disordered to an ordered phase as a durable oxygen reduction electrocatalyst.

The sluggish oxygen reduction kinetics and insufficient durability of cathode catalysts restrict the practical application of proton exchange membrane fuel cells. This study focuses on the structural transformation of carbon-supported Pt3Cr from a disordered to an ordered phase and on the effect of such structural transformation on oxygen reduction reaction (ORR) activity and durability. X-ray diffraction and transmission electron microscopy results confirm the formation of carbon-supported Pt3Cr intermetallic nanoparticles with a mean particle size of ca. 7.2 nm. Line scanning EDX reveals that the practical Pt-Cr atomic ratio is approximately 3 : 1. X-ray photoelectron spectroscopy results indicate that the proportion of metallic Pt increases while the binding energy of Pt 4f decreases with such structural transformation. The Pt3Cr/C intermetallic nanoparticles exhibit enhanced mass and specific activities toward the ORR compared with commercial Pt/C but slightly lower mass activity than the disordered Pt3Cr/C alloy nanoparticles. After the accelerated durability test for 5000 cycles, the Pt3Cr intermetallic nanoparticles displayed negligible decay in ORR mass activity; however the ORR mass activity on the isordered Pt3Cr alloy decreases to ca. 50%. Much enhanced durability of the Pt3Cr/C intermetallic nanoparticles toward the ORR is definitely caused by the much higher structural and compositional stabilities of the Pt3Cr/C intermetallic nanoparticles than that of the disordered Pt3Cr/C alloy nanoparticles, suggesting that the Pt3Cr intermetallic nanoparticles may serve as highly active and durable ORR electrocatalysts for practical application.