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Leaf senescence involves lipid droplet (LD) degradation that produces toxic fatty acids, but little is known about how the toxic metabolites are isolated from the rest of the cellular components. Our ultramicroscopic characterization of cytosolic LD degradation in central vacuole-absent cells and central vacuole-containing cells of senescent watermelon leaves demonstrated two degradation pathways: the small vacuole-associated pathway and the central vacuole-associated pathway. This provided an insight into the subcellular mechanisms for the isolation of the fatty acids derived from LDs. The central vacuole-containing cells, including mesophyll cells and vascular parenchyma cells, adopted the central vacuole-associated pathway, indicated by the presence of LDs in the central vacuole, which is believed to play a crucial role in scavenging toxic metabolites. The central vacuole-absent intermediary cells, where senescence caused the occurrence of numerous small vacuoles, adopted the small vacuole-associated pathway, evidenced by the occurrence of LDs in the small vacuoles. The assembly of organelles, including LDs, small vacuoles, mitochondria and peroxisome-like organelles, occurred in the central vacuole-absent intermediary cell in response to leaf senescence.

The morphology of sub-micron poly(methyl methacrylate) films coated to glass supports by spin coating from toluene is examined using surface profilometry. Wrinkled surfaces with local quasi-sinusoidal periodicity were seen on the surfaces of films with thicknesses of larger than 75 nm. The surface wrinkles had large aspect ratios with wavelengths in the tens of microns and amplitudes in the tens of nanometers. Wrinkles that formed during spin-coating are attributed to surface perturbations caused by Rayleigh–Bénard–Marangoni convective instabilities. The effects of film thickness, coating solution concentration, and drying rate on the thin film surface morphology are investigated. The results can be used to prepare surfaces with controlled morphology, either smooth or with periodic wrinkles.

A predictive film thickness model based on an accepted equation of state is applied to the spin-coating of sub-micron poly(methylmethacrylate) viscous thin films from toluene. Concentration effects on density and dynamic viscosity of the spin-coating solution are closely examined. The film thickness model is calibrated with a system-specific film drying rate and was observed to scale with the square root of spin speed. Process mapping is used to generate a three-dimensional design space for the control of film thickness.

Transmission electron microscopy was used to reveal a layer of multiply folded membranes that closely surrounded the tannin-accumulating vacuole in cells of honeysuckle petal trichomes. A huge amount of tannins were deposited in the peripheral region and the center of the vacuole. The prolific membranes extended to the tannins deposited along the vacuole periphery. It was difficult to distinguish the vacuole membrane, and it seemed as if it was the layer of multiply folded membranes that separated the vacuole lumen from the cytoplasm. In addition, there were also membrane assemblies in the cytoplasm away from the vacuole, which were continuous with the proliferated membranes bordering the vacuole. Therefore, the tannin-accumulating vacuole was in close association with a very large network of proliferated membranes. The occurrence of such a layer of multiply folded membranes around the tannin-accumulating vacuole might be a structural strategy for improvement of the efficiency of vacuolar accumulation of tannins.

The structure and composition of lithium ion solvation spheres of electrolyte solutions composed of common lithium salts (LiTFSI, LiPF6, LiBF4, and LiClO4) dissolved in aprotic polar linear and cyclic carbonate solvents (propylene carbonate (PC) or dimethyl carbonate (DMC)) have been investigated via a combination of FTIR, 13C NMR spectroscopy, and density functional theory (DFT). Results from the two different spectroscopic methods are in strong agreement with each other and with predictions from quantum chemistry calculations. The coordination of the carbonyl oxygen of the solvents to the lithium cation is observed by IR spectroscopy. The ratio of coordinated to uncoordinated PC and DMC has been used to determine solvent coordination numbers which range from 2 to 5 depending on salt, solvent, and concentration. The relative stability of the lithium–anion solvates were examined using DFT employing the cluster-continuum approach including changes to the intensity and frequency of the IR bands along with t...

A novel polyimide has been investigated as a conductive binder for silicon electrodes. The electrochemical properties of a polyimide electrode, derived from pyromellitic dianhydride and 4,4′-oxydianiline, were characterized and the feasibility as a binder for silicon electrodes was investigated. When fully lithiated and delithiated (3 V–5 mV), the polyimide electrode demonstrates a large reversible capacity of 826 mAh g−1 in the first cycle. The ex situ IR spectra indicate that the carbonyl groups on imide rings are irreversibly reduced during earlier period of first lithiation. Further lithiation leads to removal of characteristic peaks of PO–PI as well as a significant decrease of peak intensities, which implies changes in chemical structure of the host material. Nevertheless, the PO–PI electrode delivers large reversible capacity in subsequent cycles. In the potential range that silicon operates (0.7 V–5 mV), the polyimide electrode remains in a highly lithiated state maintaining its electric conductivity. Silicon electrodes with polyimide binder exhibit superior capacity retention and coulombic efficiency in comparison to electrodes using insulating binders. The improvements are attributed to the reinforced electrical conductive network in the electrode laminate.