High-Resolution Infrared-Vacuum Ultraviolet Photoion and Pulsed Field Ionization-Photoelectron Methods for Spectroscopic Studies of Neutrals and Cations

We show that by scanning the frequency of a single mode infrared (IR) optical parametric oscillator (IR-OPO) laser to excite the molecular species of interest and fixing the frequency of a vacuum ultraviolet (VUV) laser to photoionize the IR excited species, high-resolution IR spectra of polyatomic neutrals can be obtained with high sensitivity. The fact that this IR-VUV-photoion (IR-VUV-PI) method is based on VUV photoionization probe, and thus, allows the identification of the neutral IR absorber, makes it applicable for IR spectroscopy measurements of isotopemers, radicals, and clusters, which usually exist as impure samples. The highly resolved IR-VUV-PI measurements achieved using the single mode IR-OPO laser have made possible the selection of single rovibrational states of CH3X (X=Br and I), C2H4, and C3H4 for VUV-pulsed field ionization-photoelectron (VUV-PFI-PE) measurements, resulting in rovibrationally resolved photoelectron spectra for these polyatomic molecules. These experiments show that the signal-to-noise ratios of the IR-VUV-PI and IR-VUV-PFI-PE spectra obtained by employing the high-resolution IR-OPO laser are significantly higher than those observed in previous IR-VUV-PI and IR-VUV-PFI-PE studies using a low-resolution IR-OPO laser. Further improvement in sensitivity of IR-VUV-PI and IR-VUV-PFI-PE measurements by using the collinear arrangement of IR-VUV lasers and molecular beam is discussed.     

Dynamic synovial fibroblasts are modulated by NBCn1 as a potential target in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by aggressive fibroblast-like synoviocytes (FLSs) and pannus formation. Various therapeutic strategies have been developed against inflammatory cytokines in RA in recent decades. Based on the migratory features of FLSs, we examined whether modulation of the migratory module attenuates RA severity. In this study, inflamed synovial fluid-stimulated FLSs exhibited enhanced migration and migratory apparatus expression, and sodium bicarbonate cotransporter n1 (NBCn1) was identified in primary cultured RA-FLSs for the first time. The NBC inhibitor S0859 attenuated the migration of FLSs induced with synovial fluid from patients with RA or with TNF-α stimulation. Inhibition of NBCs with S0859 in a collagen-induced arthritis (CIA) mouse model reduced joint swelling and destruction without blood, hepatic, or renal toxicity. Primary FLSs isolated from the CIA-induced mouse model also showed reduced migration in the presence of S0859. Our results suggest that inflammatory mediators in synovial fluid, including TNF-α, recruit NBCn1 to the plasma membrane of FLSs to provide dynamic properties and that modulation of NBCn1 could be developed into a therapeutic strategy for RA.Subject terms: Chemotaxis, Bone, Ion channel signalling, Rheumatoid arthritis, Drug development     

Potential-induced wetting and dewetting in hydrophobic nanochannels for mass transport control

Wetting and dewetting transitions play a central role in controlling the hydrophobicity of the lining of biological channels in order to regulate aqueous solution permeation. Understanding of the operational characteristics of biological nanochannels led to experimental efforts to mimic their behavior and to achieve potential-induced, repeatedly-switchable wettability transitions in synthetic nanochannels in the early 2010s. Since then, research has identified conditions needed to produce reversible wettability transitions using a number of different environmental stimuli—such as light, pH, and electrostatic charge—in addition to potential. Furthermore, nascent understanding of the underlying phenomena in synthetic nanochannels was rapidly followed by practical applications, including oil–water separations, drug release, and electroactive flow control based on switchable wettability. More practical applications are being developed continuously, as the physical and chemical principles that govern hydrophobic gating at the nanoscale are further elucidated, making it possible to exploit wettability as a design element in nanofluidic systems.     

Impedance measurements on QLED devices: analysis of high-frequency loop in terms of material properties

Electrochemical impedance spectroscopy is used to study red and green quantum-dot light-emitting diodes devices. The high-frequency loop is interpreted in terms of the thickness, dielectric constant, and resistivity distribution of the hole-injection layer. The analysis employed the device capacitance obtained from a measurement model analysis, the film thickness measured by scanning electron microscopy, and an interpretation of the impedance based on a power-law model. Impedance measurements performed on hole-transport–only devices yielded results that were consistent with the interpretation of the high-frequency capacitive loop in terms of the properties of the hole-injection layer.

     

Crystallinity in quasi-alternating cycloolefin copolymers: Overcoming brittleness

Cycloolefin copolymers (COCs, which are produced via ethylene/cycloolefin copolymerization) and cycloolefin polymers (COPs, which are synthesized by a rather complicated two-step process via ring-opening metathesis polymerization and subsequent hydrogenation) are commercialized materials used especially widely in optical applications. Although a COP can be used after processing into a film, films made from conventional COCs are too brittle. Optical-grade COCs and COPs are generally known as amorphous polymers. By contrast, here, a quasi-alternating ethylene/norbornene copolymer (norbornene content 56 mol%), prepared from a constrained-geometry Hf complex, shows some melting (T_m) signals in a broad temperature range (150–200°C) in the first heating scan of differential scanning calorimetry (DSC) when the samples are prepared by precipitation from a toluene solution. In the second heating scan, only glass transition (T_g) signals are observed at ~140°C with disappearance of T_m signals. The quasi-alternating ethylene/norbornene copolymer has better mechanical properties (greater elongation at break) than random congeners, which do not show any melting signal, though elongation at break is still inferior to that of the COP which shows the melting signal in the first heating scan of DSC. The enhanced mechanical properties of the quasi-alternating ethylene/norbornene copolymer and commercial-grade COP may be ascribed to semicrystallinity observed in the first heating scan.     

Boron triflouride etherate on alimina - a modified Lewis acid reagent. : An improved synthesis of cannabidiol

Boron trifluoride etherate on alumina catalyses the condensation of resorcinols an monomethyl resorcinols with several monoterpenoid allylic alcohols: in contrast to parallel reactions with boron trifluoride etherate in solution the products obtained do not undergo further cyclisations.     

Equilibria of a class of transport equations arising in congestion control

We consider a multi-queue multi-server system with n servers (processors) and m queues. At the system there arrives a stationary and ergodic stream of m different types of requests with service requirements which are served according to the following k-limited head of the line processor sharing discipline: The first k requests at the head of the m queues are served in processor sharing by the n processors, where each request may receive at most the capacity of one processor. By means of sample path analysis and Loynes’ monotonicity method, a stationary and ergodic state process is constructed, and a necessary as well as a sufficient condition for the stability of the m separate queues are given, which are tight within the class of all stationary ergodic inputs. These conditions lead to tight necessary and sufficient conditions for the whole system, also in case of permanent customers, generalizing an earlier result by the authors for the case of n=k=1. This work was supported by a grant from the Siemens AG.     

Multistage Microfluidic Platform for the Continuous Synthesis of III–V Core/Shell Quantum Dots

We present a fully continuous chip microreactor‐based multistage platform for the synthesis of quantum dots with heterostructures. The use of custom‐designed chip reactors enables precise control of heating profiles and flow distribution across the microfluidic channels while conducting multistep reactions. The platform can be easily reconfigured by reconnecting the differently designed chip reactors allowing for screening of various reaction parameters during the synthesis of nanocrystals. III–V core/shell quantum dots are chosen as model reaction systems, including InP/ZnS, InP/ZnSe, InP/CdS and InAs/InP, which are prepared in flow using a maximum of six chip reactors in series.     

Synthesis of star‐shaped copolymers with methyl methacrylate and n‐butyl methacrylate by metal‐catalyzed living radical polymerization: Block and random copolymer arms and microgel cores

Various star‐shaped copolymers of methyl methacrylate (MMA) and n‐butyl methacrylate (nBMA) were synthesized in one pot with RuCl₂(PPh₃)₃‐catalyzed living radical polymerization and subsequent polymer linking reactions with divinyl compounds. Sequential living radical polymerization of nBMA and MMA in that order and vice versa, followed by linking reactions of the living block copolymers with appropriate divinyl compounds, afforded star block copolymers consisting of AB‐ or BA‐type block copolymer arms with controlled lengths and comonomer compositions in high yields (≥90%). The lengths and compositions of each unit varied with the amount of each monomer feed. Star copolymers with random copolymer arms were prepared by the living radical random copolymerization of MMA and nBMA followed by linking reactions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 633–641, 2002; DOI 10.1002/pola.10145