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In this paper, we introduce the Layer-Peeled Model, a nonconvex, yet analytically tractable, optimization program, in a quest to better understand deep neural networks that are trained for a sufficiently long time. As the name suggests, this model is derived by isolating the topmost layer from the remainder of the neural network, followed by imposing certain constraints separately on the two parts of the network. We demonstrate that the Layer-Peeled Model, albeit simple, inherits many characteristics of well-trained neural networks, thereby offering an effective tool for explaining and predicting common empirical patterns of deep-learning training. First, when working on classbalanced datasets, we prove that any solution to this model forms a simplex equiangular tight frame, which, in part, explains the recently discovered phenomenon of neural collapse [V. Papyan, X. Y. Han, D. L. Donoho, Proc. Natl. Acad. Sci. U.S.A. 117, 24652-24663 (2020)]. More importantly, when moving to the imbalanced case, our analysis of the Layer-Peeled Model reveals a hithertounknown phenomenon that we term Minority Collapse, which fundamentally limits the performance of deep-learning models on theminority classes. In addition, we use the Layer-Peeled Model to gain insights into how to mitigate Minority Collapse. Interestingly, this phenomenon is first predicted by the Layer-Peeled Model before being confirmed by our computational experiments. [ABSTRACT FROM AUTHOR]

While the β-lactam antibiotics are known to be susceptible to oxidative degradation by sulfate radical (4•-), here we report that peroxymonosulfate (PMS) exhibits specific high reactivity toward β-lactam antibiotics without SO4•- generation for the first time. Apparent second-order reaction constants (k2,app) were determined for the reaction of PMS with three penicillins, five cephalosporins, two carbapenems, and several structurally related chemicals. The pH-dependency of k2,app could be well modeled based on species-specific reactions. On the basis of reaction kinetics, stoichiometry, and structure–activity assessment, the thioether sulfur, on the six- or five-membered rings (penicillins and cephalosporins) and the side chain (carbapenems), was the main reaction site for PMS oxidation. Cephalosporins were more reactive toward PMS than penicillins and carbapenems, and the presence of a phenylglycine side chain significantly enhanced cephalosporins' reactivity toward PMS. Product analysis indicated oxidation of β-lactam antibiotics to two stereoisomeric sulfoxides. A radical scavenging study and electron paramagnetic resonance (EPR) technique confirmed lack of involvement of radical species (e.g., 4•-). Thus, the PMS-induced oxidation of β-lactam antibiotics was proposed to proceed through a nonradical mechanism involving direct two-electron transfer along with the heterolytic cleavage of the PMS peroxide bond. The new findings of this study are important for elimination of β-lactam antibiotic contamination, because PMS exhibits specific high reactivity and suffers less interference from the water matrix than the radical process. [ABSTRACT FROM AUTHOR]

Two new flavones, 5-hydroxy-8-hydroxymethyl-7,4′-dimethoxy-flavone ( 1) and 6-hydroxy-8-hydroxymethyl-7,4′-dimethoxy-flavone ( 2), together with six known flavones ( 3-8), were isolated from the bark of Lindera caudata. The structures of 1-8 were elucidated by spectroscopic methods including extensive 1D and 2D NMR techniques. Compounds 1-8 were evaluated for their anti-tobacco mosaic virus (anti- TMV) activity. The results showed that Compounds 1 and 2 showed high anti- TMV activity with inhibition rates of 31.2 and 28.8%, respectively. These values are close to those of positive control. [ABSTRACT FROM AUTHOR]

Two new anthraquinones, siameaquinones A ( 1) and B ( 2), together with seven known anthraquinones ( 3-9), were isolated from the stems of Cassia siamea. The structure of 1-9 was elucidated by spectroscopic methods, including extensive D and D NMR techniques. Compounds 1 and 2 were also evaluated for their cytotoxicities against five human tumor cell lines. The results revealed that compound 1 showed moderate cytotoxicities against A549 and SHSY5Y cells with IC values of 5.2 and 6.3 μM, and compound 2 showed moderate cytotoxicities against NB4 and SHSY5Y cells with IC values of 8.8 and 7.5 μM, respectively. [ABSTRACT FROM AUTHOR]

Two new butyrolactones, asperphenol A (1) and B (2), together with four known butyrolactones (3-6) were isolated from the fermentation products of an endophytic fungus Aspergillus versicolor. Their structures were elucidated by spectroscopic methods including extensive 1D- and 2D-NMR techniques. Compounds 1-6 were also tested for their anti-tobacco mosaic virus (anti-TMV) activities. The results showed that compound 2 exhibited high anti-TMV activity with inhibition rate of 46.7%. The other compounds also exhibited potential anti-TMV activities with inhibition rates in the range of 21.8-28.4%. [ABSTRACT FROM AUTHOR]

Highlights: [•] The reaction of aromatic amino acids with intermediates of lignin biosynthesis was examined. [•] Products formed from reaction of amino acids with intermediates of lignin biosynthesis were identified by mass spectroscopy. [•] Amino acid adducts were formed with Tyr, Thr and Cys through a reaction of the side-chain with the quinone methide. [•] The cross-coupling was also shown to occur at the protein level. [•] These results show how peptide linkages can be introduced into the lignin polymer. [Copyright &y& Elsevier]

The purpose of this study was to evaluate the effect of sequential embryo transfer in patients with repeated IVF failure. A retrospective matched case-control study was conducted and the outcomes of 213 patients with a history of repeated IVF-embryo transfer failure were analysed, of which 33 women underwent sequential embryo transfer on day 2 and day 3 (D2/D3 group), 66 women on day 3 and day 5 (D3/D5 group), 85 women underwent day-3 embryo transfer only (D3 control group) and 29 women underwent day-5 embryo transfer only (D5 control group) in the assisted reproduction centre of the Sixth Affiliated Hospital of Sun Yat-sen University from August 2010 to December 2011. The results showed that the clinical pregnancy rate of the D2/D3 group was higher than that of the D3 group (48.5% versus 22.4%, P = 0.006) white the clinical pregnancy rates of the D3/D5 and D5 groups were not significantly different (50.9% versus 45.8%). Day-2 and day-3 sequential embryo transfer may improve the clinical outcomes for patients with repeated IVF-embryo transfer failures. [ABSTRACT FROM AUTHOR]

The optically active tetra- β-[( S)-2-octanyloxy]-substituted copper and nickel phthalocyanines were synthesized via a two-step route with 4-nitro-phthalonitrile and ( S)-2-octanol as the starting materials. Both compounds are fully characterized by MS, H NMR, UV-Vis, IR, CD and elemental analysis, and soluble in common organic solvents except methanol. The results showed that they were dispersed into single molecules in chloroform and dichloromethane, but prone to congregate into H-type aggregates in ethanol and diethyl ether. They assembled to H-type aggregates with left-handed helix when deposited as thin films. [ABSTRACT FROM AUTHOR]

Purpose The aim of this study is to investigate the relationship between spindle location and embryonic development of in vivo and in vitro matured human oocytes. Methods The spindles of 134 in vivo matured, 105 in vitro matured oocytes were examined by Polscope at the time of ICSI. Results The spindles were visualized in 83.6 and 77.1% of in vivo and in vitro matured oocytes respectively. The rate of fertilization of in vivo matured oocytes with spindles beneath or adjacent to the first polar body (angle of 0-5°) was significantly higher (93.3%) than all other groups. The proportions of various spindle positions did not differ statistically in in vivo and in vitro matured oocytes. Conclusions Meiotic spindle location with regard to the first polar body appears to influence fertilization rate. [ABSTRACT FROM AUTHOR]

Abstract: The UV–vis spectra of peripherally substituted tetranitrometallophthalocyanines (TNMPcs) 1a–1d and non-peripherally substituted TNMPcs 2a–2d were investigated. In comparison of 1a with 2a, there is the only difference in the substitution position of nitro-groups. The structural diversity of 1a and 2a resulted in different electronic effects of nitro-group on Pc rings, which caused them have two kinds of Q bands. The Q band in the UV–vis spectra of 1a–1d was split into two peaks, which were obviously influenced by temperature, while no split was observed in the Q band of 2a–2d. We can draw a conclusion that tuning nitro-group electronic effect is an important approach for controlling the properties of Pcs. [Copyright &y& Elsevier]

Abstract: Teraaminometallophthylocyanines (TAMPcs) 3a1 –3a4 and 3b1 –3b4 were prepared, in two steps, from 3-nitro-phthalic anhydride and 4-nitro-o-phenyleneimine, respectively. Although simple methods were employed without using chromatographic fractionation, purer products with higher yields were obtained. Synthesized compounds were characterized by MS, 1H NMR, UV–VIS and IR. Characterization results showed that 3a1 –3a4 contained intramolecular hydrogen bonds, while 3b1 –3b4 did not contain intramolecular hydrogen bonds. Property comparisons between 3a1 –3a4 and 3b1 –3b4 are presented in this paper. [Copyright &y& Elsevier]

Abstract: Although the enantioselectivity of the Pseudomonas cp. lipase (PCL) used in the kinetic resolution of (R, S)-2-octanol is moderate, the (S)-enantiomer 2 with 98% ee and (R)-enantiomer 6 with 95% ee can be obtained by combining dynamic kinetic resolution (DyKR) with double kinetic resolution (DoKR) and 80% racemic substrate can be converted to enantiopure products by the way. The method is based on the feasibility of using the residue of one DoKR as the substrate of the next DoKR and so on recycling them to DyKR. The strategy is adapted to large-scale resolution of common sec-alcohols, especially to which when the moderate enantioselective lipases can be employed. [Copyright &y& Elsevier]

In this work, we investigated the magnetoelectric (ME) coefficients and equivalent magnetic noises of Metglas/Mn-doped Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMNT) laminate composites with an in-plane series connected structure. An average-field method as well as a finite element simulation are employed to analyze the variation of the ME coefficients of a number of Mn-doped PMNT fibers (N). Both the theoretical and experimental results verify that the equivalent magnetic noises (EMNs) decrease obviously with an increasing N. Using this structure, the measured EMN of the Metglas/Mn-PMNT composite is as low as 0.87pT/Hz1/2 at 30Hz for N  =  7, which is 1.8 times lower than that for N  =  1. Such a low EMN holds considerable promise for practical ME magnetic sensors. [ABSTRACT FROM AUTHOR]

Branched-chain fatty acids (BCFAs) and odd-chain fatty acids (OCFAs) in mammalian milk, dairy products, and vegetable oils were investigated; 72 fatty acids, including 16 BCFAs and 10 OCFAs, were identified and quantified using GC/TOF-MS. Human milk showed the lowest content of BCFA (0.4% of total FA) and the content in other milk ranged from 2 to 6%, of which ai 17:0, i 17:0, ai 15:0 and i 15:0 were most abundant. Differences in the content of OCFA in mammalian milk trended similarly to differences in BCFA content. The molecular species of BCFA in cow milk-derived dairy products were identical, but the content was different, with higher content in fermented dairy products. Apparent differences in BCFA and OCFA composition were found in infant formulas, strongly related to their fat sources. Vegetable oils contained no BCFA and a small amount of OCFA. A scientific basis for further investigation of high-BCFA and OCFA dairy products is provided. [ABSTRACT FROM AUTHOR]

Context: Polygonum multiflorum Thunb. (Polygonaceae) (PM) can cause potential liver injury which is typical in traditional Chinese medicines (TCMs)-induced hepatotoxicity. The mechanism involved are unclear and there are no sensitive evaluation indicators. Objective: To assess PM-induced liver injury, identify sensitive assessment indicators, and screen for new biomarkers using sphingolipidomics. Materials and methods: Male Sprague-Dawley (SD) rats were randomly divided into four groups (control, model with low-, middle- and high-dose groups, n=6 each). Rats in the three model groups were given different doses of PM (i.g., low/middle/high dose, 2.7/8.1/16.2 g/kg) for four months. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels in the plasma and liver were quantitatively analyzed. Fixed liver tissue sections were stained with haematoxylin and eosin and examined under a light microscope. The targeted sphingolipidomic analysis of plasma was performed using high-performance liquid chromatography tandem mass spectrometry. Results: The maximal tolerable dose (MTD) of PM administered intragastrically to mice was 51 g/kg. Sphingolipid profiling of normal and PM-induced liver injury SD rats revealed three potential biomarkers: ceramide (Cer) (d18:1/24:1), dihydroceramide (d18:1/18:0)-1-phosphate (dhCer (d18:1/18:0)-1P) and Cer (d18:1/26:1), at 867.3-1349, 383.4-1527, and 540.5-658.7 ng/mL, respectively. A criterion for the ratio of Cer (d18:1/24:1) and Cer (d18:1/26:1) was suggested and verified, with a normal range of 1.343-2.368 (with 95% confidence interval) in plasma. Conclusions: Three potential biomarkers and one criterion for potential liver injury caused by PM that may be more sensitive than ALT and AST were found. [ABSTRACT FROM AUTHOR]

RAS proteins are signal transduction gatekeepers that mediate cell growth, survival, and differentiation through interactions with multiple effector proteins. The RAS effector RAS- and RAB-interacting protein 1 (RIN1) activates its own downstream effectors, the small GTPase RAB5 and the tyrosine kinase ABL, to modulate endocytosis and cytoskeleton remodeling. To identify ABL substrates downstream of RAS-to-RIN1 signaling, we examined human HEK293T cells overexpressing components of this pathway. Proteomic analysis revealed several novel phosphotyrosine peptides, including Harvey rat sarcoma oncogene (HRAS)-pTyr137. Here we report that ABL phosphorylates tyrosine 137 of H-, K-, and NRAS. Increased RIN1 levels enhanced HRAS-Tyr137 phosphorylation by nearly 5-fold, suggesting that RAS-stimulated RIN1 can drive ABL-mediated RAS modification in a feedback circuit. Tyr137 is well conserved among RAS orthologs and is part of a transprotein H-bond network. Crystal structures of HRASY137F and HRASY137E revealed conformation changes radiating from the mutated residue. Although consistent with Tyr137 participation in allosteric control of HRAS function, the mutations did not alter intrinsic GTP hydrolysis rates in vitro. HRAS-Tyr137 phosphorylation enhanced HRAS signaling capacity in cells, however, as reflected by a 4-fold increase in the association of phosphorylated HRASG12V with its effector protein RAF proto-oncogene serine/threonine protein kinase 1 (RAF1). These data suggest that RAS phosphorylation at Tyr137 allosterically alters protein conformation and effector binding, providing a mechanism for effector-initiated modulation of RAS signaling. [ABSTRACT FROM AUTHOR]

Linear magnetoelectric (ME) and nonlinear magnetoelectric effects are considered systematically in this paper. We have prepared 3 multi-push-pull magnetoelectric laminated composites Metglas/ PMNT/Metglas with n layers metglas (n=1, 2, and 3). When n increases from 1 to 3, the linear magnetoelectric charge coefficients increase from 1900 to 2200 and then to 2600 pC/Oe at 2Hz under their each optimal magnetic bias. By using these 3 ME composites, we have also prepared 3 ME sensors, the sensitivity of which are as low as 130, 168, and 199 pT√Hz at 1Hz for n=1, 2, and 3, respectively, via nonlinear modulation method. Therefore, the nonlinear ME charge coefficients decrease as layer numbers of metglas increase, which is different with the ME charge linear coefficient's increasing trend, also demonstrated coupled with the finite element analysis method. The factors that result in the higher nonlinear ME charge coefficient in ME composites with fewer metglas layers are analyzed and discussed in detail. [ABSTRACT FROM AUTHOR]

• Ruminant milk and meat contain high content BCFA, of which i BCFA and ai BCFA each half. • BCFA could de novo synthesized from BCAA in bacteria, C. elegans , and mammal. • BCFA regulated intestinal flora and important to intestinal anti-inflammatory in newborn, especially premature. • BCFA in microbial membrane lipids may regulate immune homeostasis. • Low mmBCFA levels were found in the serums of obese patients compared to lean controls. Branched-chain fatty acids (BCFAs) consist of a wide variety of fatty acids with alkyl branching of methyl group. The most common BCFAs are the types with one methyl group (mmBCFA) on the penultimate carbon (i BCFA) or the antepenultimate carbon (ai BCFA). Long-chain mmBCFAs are widely existing in animal fats, milks and are mostly derived from bacteria in the diet or animal digestive system. Recent studies show that BCFAs benefit human intestinal health and immune homeostasis, but the connection between their content, distribution in the human and their nutritional functions are not well established. In this paper, we reviewed BCFAs from various dietary sources focused on their molecular species. The BCFAs biosynthesis in bacteria, Caenorhabditis elegans , mammals and their distribution in human tissues are summarized. This paper also discusses the nutritional properties of BCFAs including influences on intestinal health, immunoregulatory effects, anti-carcinoma, and anti-obesity activities, by highlighting the most recent research progress. [ABSTRACT FROM AUTHOR]

Three new isocoumarins, caudacoumarins A-C (I), are isolated along with two known ones from the bark of Lindera caudata. [ABSTRACT FROM AUTHOR]

Two new chalcones, 2′,4-hydroxy-3,4′-dimethoxychalcone ( 1 ) and 2′,3-hydroxy-4,4′-dimethoxychalcone ( 2 ), together with four known chalcones ( 3-6 ), were isolated from the whole plant of Desmodium podocarpum . All of their structures were determined by spectroscopic methods including 1D and 2D NMR. Compounds 1 and 2 were evaluated for their cytotoxicity using five tumor cell lines. Compound 1 exhibited cytotoxicity against SHSY5Y and PC3 cells with IC values of 3.8 and 3.6 μM, and compound 2 exhibited cytotoxicity against A549 cells with IC value of 3.5 μM, respectively. [ABSTRACT FROM AUTHOR]

isolation and structure elucidation of two new flavones (Ia,b) [ABSTRACT FROM AUTHOR]

isolation, structure and cytotoxicity of oxyphyllumflavone A and B, the first naturally occurring flavones possessing a six-membered 6-methyl-α-pyrone ring [ABSTRACT FROM AUTHOR]