Visualization 2: Design of a superoscillatory lens for a polarized beam

Structures of the SOLs in Table 1. Originally published in JOSA B on 01 August 2015 (josab-32-8-1731

Visualization 1: Design of a superoscillatory lens for a polarized beam

Structures of the SOLs in Figure 2. Originally published in JOSA B on 01 August 2015 (josab-32-8-1731

Functionalization of Electrospun Poly(vinyl alcohol) (PVA) Nanofiber Membranes for Selective Chemical Capture

Electrospun poly­(vinyl alcohol) (PVA) nanofiber membranes were functionalized by incorporating either poly­(methyl vinyl ether-<i>alt</i>-maleic anhydride) (PMA) to create negative charges, or poly­(hexadimethrine bromide) (PB) and chitosan (CS) to create positive charges on the fiber surface. The functionalized PVA nanofiber membranes were heat-treated at elevated temperatures to impart cross-linking and improve the water-resistance. The optimum heat-treatment temperatures for both PVA/PMA and PVA/PB/CS systems were screened by Fourier transformed infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Formation of cross-linked structure and increased crystallinity were triggered by the heat-treatment. A cationic dye, methylene blue (MB), and an anionic dye, acid red 1 (AR1), were used to represent charged moieties in solution. The surface-charged PVA nanofiber membranes were able to selectively capture counter-charged dye molecules from aqueous solutions. The capture processes obey the pseudo-second-order kinetic model. The capture equilibrium can be well-described by the Langmuir model. Chemically cross-linked PVA/PMA nanofiber membranes exhibited higher strength in capturing counter-charged dyes than physically cross-linked PVA/PB/CS nanofiber membranes. Selective chemical capture studies indicated that, by tailoring the surface, functionalized PVA nanofiber membranes were able to selectively remove charged chemicals with potential applications for purifying mixed liquids and delivering a pure sample for detection in small-scale testing systems

Threading Immobilized DNA Molecules through a Solid-State Nanopore at >100 μs per Base Rate

In pursuit of developing solid-state nanopore-based DNA sequencing technology, we have designed and constructed an apparatus that can place a DNA-tethered probe tip near a solid-state nanopore, control the DNA moving speed, and measure the ionic current change when a DNA molecule is captured and released from a nanopore. The probe tip’s position is sensed and controlled by a tuning fork based feedback force sensor and a nanopositioning system. Using this newly constructed apparatus, a DNA strand moving rate of >100 μs/base or <1 nm/ms in silicon nitride nanopores has been accomplished. This rate is 10 times slower than by manipulating DNA-tethered beads using optical tweezers and 1000 times slower than free DNA translocation through solid-state nanopores reported previously, which provides enough temporal resolution to read each base on a tethered DNA molecule using available single-channel recording electronics on the market today. This apparatus can measure three signals simultaneously: ionic current through a nanopore, tip position, and tip vibrational amplitude during the process of a DNA molecule’s capture and release by a nanopore. We show results of this apparatus for measuring λ DNA’s capture and release distances and for current blockage signals of λ DNA molecules biotinylated with one end and with both ends tethered to a tip

Energy Transfer of Biexcitons in a Single Semiconductor Nanocrystal

Photoluminescence (PL) decay dynamics of multiexcitons in semiconductor nanocrystals (NCs) are dominated by the nonradiative Auger effect, making it difficult to explore their basic optical processes such as radiative recombination and energy transfer (ET). Here we constructed a single-particle ET system by attaching several acceptor dyes to the surface of a donor NC to study the ET of biexcitons at a single-NC level. By comparing the single-exciton and biexciton PL lifetimes of the same donor NC before and after the acceptor dyes were bleached, their respective ET lifetimes could be reliably extracted without the Auger influence. From statistical measurements on a large number of single ET particles, the average ET rate ratio between biexcitons and single excitons was estimated to be larger than four, and the same scaling rule could be naturally extended to their radiative rates

Enzymatic Synthesis of Rhamnose Containing Chemicals by Reverse Hydrolysis

<div><p>Rhamnose containing chemicals (RCCs) are widely occurred in plants and bacteria and are known to possess important bioactivities. However, few of them were available using the enzymatic synthesis method because of the scarcity of the α-L-rhamnosidases with wide acceptor specificity. In this work, an α-L-rhamnosidase from <i>Alternaria</i> sp. L1 was expressed in <i>Pichia pastroris</i> strain GS115. The recombinant enzyme was purified and used to synthesize novel RCCs through reverse hydrolysis in the presence of rhamnose as donor and mannitol, fructose or esculin as acceptors. The effects of initial substrate concentrations, reaction time, and temperature on RCC yields were investigated in detail when using mannitol as the acceptor. The mannitol derivative achieved a maximal yield of 36.1% by incubation of the enzyme with 0.4 M L-rhamnose and 0.2 M mannitol in pH 6.5 buffers at 55°C for 48 h. In identical conditions except for the initial acceptor concentrations, the maximal yields of fructose and esculin derivatives reached 11.9% and 17.9% respectively. The structures of the three derivatives were identified to be α-L-rhamnopyranosyl-(1→6')-D-mannitol, α-L-rhamnopyranosyl-(1→1')-β-D-fructopyranose, and 6,7-dihydroxycoumarin α-L-rhamnopyranosyl-(1→6')-β-D-glucopyranoside by ESI-MS and NMR spectroscopy. The high glycosylation efficiency as well as the broad acceptor specificity of this enzyme makes it a powerful tool for the synthesis of novel rhamnosyl glycosides.</p></div

Supplement 1: Interacting photon pulses in a Rydberg medium

1 Originally published in Optica on 20 October 2016 (optica-3-10-1095

Effects of initial esculin concentrations on RCC-III synthesis.

<p>Data points represent the means ± S.D. of three replicates.</p

Effects of temperature (a) and pH (b) on activity (Δ) and stability (■) of recombinant RhaL1.

<p>Data points represent the means ± S.D. of three replicates.</p

A Novel Single-Ion-Conducting Polymer Electrolyte Derived from CO₂‑Based Multifunctional Polycarbonate

This work demonstrates the facile and efficient synthesis of a novel environmentally friendly CO₂-based multifunctional polycarbonate single-ion-conducting polymer electrolyte with good electrochemistry performance. The terpolymerizations of CO₂, propylene epoxide (PO), and allyl glycidyl ether (AGE) catalyzed by zinc glutarate (ZnGA) were performed to generate poly­(propylene carbonate allyl glycidyl ether) (PPCAGE) with various alkene groups contents which can undergo clickable reaction. The obtained terpolymers exhibit an alternating polycarbonate structure confirmed by ¹H NMR spectra and an amorphous microstructure with glass transition temperatures (<i>T</i>_g) lower than 11.0 °C evidenced by differential scanning calorimetry analysis. The terpolymers were further functionalized with 3-mercapto­pro­pionic acid via efficient thiol–ene click reaction, followed by reacting with lithium hydroxide, to afford single-ion-conducting polymer electrolytes with different lithium contents. The all-solid-state polymer electrolyte with the 41.0 mol % lithium containing moiety shows a high ionic conductivity of 1.61 × 10^–4 S/cm at 80 °C and a high lithium ion transference number of 0.86. It also exhibits electrochemical stability up to 4.3 V vs Li⁺/Li. This work provides an interesting design way to synthesize an all-solid-state electrolyte used for different lithium batteries