Micro FTIR Mapping of Nanometer Ferroelectric Polymer Films

Summary: Highly crystalline ferroelectric polymer films [vinyidene fluoride and trifluoroethylene, β‐P(VDF‐TrFE), 260–15 nm thick] were characterized with FTIR reflectance‐transmission microspectroscopy (FTIR‐RTM) mapping technique (400 µm × 400 µm spatial resolution). The amorphous and crystalline fractions were identified locally. FTIR‐RTM maps (1 cm² area) provided a unique in‐depth view of the ultrathin films. Lower film thickness suppressed growth of the crystalline phase. Increased content of amorphous phase lead to non‐uniform films with degraded ferroelectric behavior.

FTIR‐RTM maps of the distribution of the amorphous phase in the 80 and 35 nm films.     

Comprehensive profiles and diagnostic value of menopausal-specific gut microbiota in premenopausal breast cancer

In Western countries, breast cancer tends to occur in older postmenopausal women. However, in Asian countries, the proportion of younger premenopausal breast cancer patients is increasing. Increasing evidence suggests that the gut microbiota plays a critical role in breast cancer. However, studies on the gut microbiota in the context of breast cancer have mainly focused on postmenopausal breast cancer. Little is known about the gut microbiota in the context of premenopausal breast cancer. This study aimed to comprehensively explore the gut microbial profiles, diagnostic value, and functional pathways in premenopausal breast cancer patients. Here, we analyzed 267 breast cancer patients with different menopausal statuses and age-matched female controls. The α-diversity was significantly reduced in premenopausal breast cancer patients, and the β-diversity differed significantly between breast cancer patients and controls. By performing multiple analyses and classification, 14 microbial markers were identified in the different menopausal statuses of breast cancer. Bacteroides fragilis was specifically found in young women of premenopausal statuses and Klebsiella pneumoniae in older women of postmenopausal statuses. In addition, menopausal-specific microbial markers could exhibit excellent discriminatory ability in distinguishing breast cancer patients from controls. Finally, the functional pathways differed between breast cancer patients and controls. Our findings provide the first evidence that the gut microbiota in premenopausal breast cancer patients differs from that in postmenopausal breast cancer patients and shed light on menopausal-specific microbial markers for diagnosis and investigation, ultimately providing a noninvasive approach for breast cancer detection and a novel strategy for preventing premenopausal breast cancer.Subject terms: Bacterial genetics, Breast cancer     

Simultaneous analysis of atmospheric halocarbons and non-methane hydrocarbons using two-dimensional gas chromatography

A gas chromatographic system was constructed to simultaneously measure ambient non-methane hydrocarbons (NMHCs) and halocarbons, which play significant roles in tropospheric ozone formation and stratospheric ozone loss, respectively. A heart-cut device based on a Deans switch was connected to two capillary columns to cover the full range of NMHCs and halocarbons. Analytes more volatile than C₆ NMHCs and the halocarbon CFC-113 were separated with a PLOT column, while the remaining less volatile compounds were separated with a DB-1 column. Merge-and-split of the flows at the end of the two columns allowed the NMHCs and halocarbons to be observed simultaneously by electron capture detection (ECD) and flame ionization detection (FID). To avoid peak-overlap from the two columns while merging, programmed pressures were incorporated to control the Deans switch. In addition to the advantage of measuring two important classes of compounds in the atmosphere at the same time, this method has the additional benefit of using the homogeneity of atmospheric CFC-113 as an “intrinsic” internal reference. Thus, better data continuity, less consumption of gas standards, and real-time quality control can all be achieved.     

A Monomer‐Micelle Model for the Formation of Simple Taurocholate Micelles

A kinetic dialysis technique was used to validate a relationship between monomer taurocholate (TC) concentration and total TC concentration in TC solutions containing 0.15 M NaCl and 0.01 M buffer (pH = 7.4). Based on the experimental data and Mukerjee's equations, the number average degree and the weight average degree of TC aggregates were estimated to be nearly the same (～5), indicating that simple TC micelles were the only aggregates. Furthermore, the TC dimer concentration was quantified to be negligible. According to the validated relationship, aggregation number of 5 for simple TC micelles, and the definition of critical micelle concentration (CMC), a modified monomer‐micelle model was used for describing simple TC micelle formation. Moreover, the CMC value was estimated to be ～6.3 mM, which is consistent with the reported value of ～6.0 mM.     

Determination of Total Polyphenol Glycosides in Polygoni Cuspidati Rhizoma and Rumecis Radix

Polyphenol glycosides are reported to be hydrolyzed to lower polar aglycones and then become absorbable in the intestine. It would be more reasonable if the total glycosides of active ingredients could be assayed. In this study, the contents of polyphenol glycosides in Chinese herbs—Polygoni cuspidati rhizoma and Rumecis radix—were studied. The contents of aglycones were determined in decoctions of the herbs before and after hydrolysis. The aglycones assayed were emodin and resveratrol for Polygoni cuspidati rhizoma, and emodin and chrysophanol for Rumecis radix. The results showed that the contents of aglycones in Rumecis radix and Polygoni cuspidati rhizoma increased by 9227% and 4930%, respectively, after hydrolysis. In addition, the content of emodin in Polygoni cuspidati rhizoma increased after hydrolysis (9187%), whereas the amount of resveratrol was decreased (40%) as heating time increased. The method in this study can be applied to the determinations of the contents of aglycones and their glycosides in these Chinese herbs for quality control.     

Methyl-oxygen bond cleavage in hemilabile phosphine-ether ligand of ruthenium(II) complexes

The preparation and characterization are described for four ruthenium(II) complexes containing hemilabile phosphine-ether ligand o-(diphenylphosphino)anisole (Ph₂PC₆H₄OMe-o) and/or bidentate ligand diphenylphosphino-phenolate ([Ph₂PC₆H₄O-o]⁻) Ru(RCN)₂(κ²-Ph₂PC₆H₄O-o)₂ (1a: R = Me; 1b: R = Et) and [Ru(RCN)₂(κ²-Ph₂PC₆H₄O-o)(κ²-Ph₂PC₆H₄OMe-o)](PF₆) (2a: R = Me; 2b: R = Et). The ruthenium(II) phosphine-ether complexes undergo mild methyl-oxygen bond cleavage. Two different kinds reaction mechanism are proposed to describe the methyl-oxygen bond cleavage, one involving attack of anionic nucleophiles and another involving the phosphine. The new reactions define novel routes to phosphine-phenolate complexes. The structures of complexes 1a, 1b and 2a were confirmed by X-ray crystallography.     

Phonon-induced gaps in graphene and graphite observed by angle-resolved photoemission

Mapping by angle-resolved photoemission spectroscopy of the spectral functions of graphite and graphene layers at low temperatures reveals a heretofore unreported gap of ~ 67 meV at normal emission. This gap persists to room temperature and beyond, and diminishes for increasing emission angles. We show that this gap arises from electronic coupling to out-of-plane vibrational modes at the K(ˉ) point in the surface Brillouin zone in accordance with conservation laws and selection rules governed by quantum mechanics. Our study suggests a new approach for characterizing phonons and electron-phonon coupling in solids.     

Nonlocality and particle-clustering effects on the optical response of composite materials with metallic nanoparticles

The optical properties of composites with metallic nanoparticles are studied, taking into account the effects due to the nonlocal dielectric response of the metal and the coalescing of the particles to form clusters. An approach based on various effective medium theories is followed, and the modeling results are compared with those from the cases with local response and particles randomly distributed through the host medium. Possible observations of our modeling results are illustrated via a calculation of the transmission of light through a thin film made of these materials. It is found that the nonlocal effects are particularly significant when the particles coalesce, leading to blue-shifted resonances and slightly lower values in the dielectric functions. The dependence of these effects on the volume fraction and fractal dimension of the metal clusters is studied in detail.