Probe Spectroscopy Research Articles

Incidence of medical device-related pressure injuries and identification of risk factors in the neonatal unit

AimThis study was conducted to investigate the incidence of medical device-related pressure injuries (MDRPIs) and the risk factors influencing their occurrence in the neonatal intensive care unit (NICU). MethodThis study is a prospective, descriptive study. The research was conducted with 116 newborns between June 1, 2022, and June 1, 2023. Newborns who stayed in the neonatal intensive care unit for at least 24 h were observed daily for medical device-related pressure injuries under and around each medical device throughout their stay in the intensive care unit. The "Case Report Form," "MDRPIs Monitoring Form," "Braden Q scale for children," National Pressure Injury Advisory Panel (NPIAP) Pressure Grading, and Glasgow Coma Scale were used in the research. ResultsThe incidence of medical device-related pressure injuries is 35.3 % (41/116). It was found that 38.1 % (16/42) of medical device-related pressure injuries developed due to Near-Infrared Spectroscopy (NIRS) probes, and 33.5 % (14/42) developed due to medical devices related to the respiratory system. In terms of anatomical location, 38.1 % occurred on the forehead, and 23.8 % on the arm/leg. The difference between birth weight, gestational age, development of MDRPIs in newborns receiving sedation and inotropes was found to be statistically significant. Regression analysis identified gestational age (p = 0.040, OR = 0.795, 95%CI = [0.632–1.000]) as an independent risk factor for the occurrence of medical device-related pressure injuries. ConclusionsThe incidence of medical device-related pressure injuries in newborns was relatively high in this study, with gestational age being the most significant risk factor for MDRPIs formation. It is crucial for neonatal intensive care nurses to consider associated risk factors while providing newborn care and implement appropriate preventive measures to reduce the incidence of MDRPIs.

Influence of umbilical cord clamping time on cerebral oxygenation and early cardiac function in term infants.

Delayed cord clamping is the standard of care for both term and preterm infants worldwide. The aim of this study was to evaluate the effect of 60-second or 180-second delayed cord clamping during labor on cerebral oxygenation and cardiac function. Healthy newborns were divided into two groups: a 60-second delay in cord clamping (60-s DCC) and a 180-second delay in cord clamping (180-s DCC) at birth. Pulse oximetry and cerebral near-infrared spectroscopy (cNIRS) probes were placed during postnatal care. A total of 84 healthy newborns were included in this study. Preductal oxygen saturation (SpO2), heart rate, and cNIRS values were recorded at 5 and 10 minutes after delivery. The cardiac function of the infants was assessed by echocardiography at 3-7 days postnatally. There was no significant difference between the groups in SpO2 and cNIRS values at 5 and 10 min. While there was no significant difference in the number of neonates with targeted SpO2 at the 5th and 10th min and targeted cNIRS values at the 10th min, there was a significant difference in the number of neonates with target cNIRS values at the 5th min between groups (p < 0.001). Echocardiographic findings showed that pulmonary flow velocity was increased in the 180-s DCC group; the difference was statistically significant (p = 0.04). Our results showed that the number of infants with normal cNIRS values regarding cerebral oxygenation was higher in the 180-s DCC group. The pulmonary flow velocity was significantly increased in the 180-s DCC group in terms of echocardiographic findings.

Evolution of fluid redox in a fault zone of the Pic de Port Vieux thrust in the Pyrenees Axial Zone (Spain)

Abstract. In mountain ranges, crustal-scale faults localize multiple episodes of deformation. It is therefore common to observe current or past geothermal systems along these structures. Understanding the fluid circulation channelized in fault zones is essential to characterize the thermochemical evolution of associated hydrothermal systems. We present a study of a palaeo-system of the Pic de Port Vieux thrust fault. This fault is a second-order thrust associated with the Gavarnie thrust in the Axial Zone of the Pyrenees. The study focused on phyllosilicates which permit the constraint of the evolution of temperature and redox of fluids at the scale of the fault system. Combined X-ray absorption near-edge structure (XANES) spectroscopy and electron probe microanalysis (EPMA) on synkinematic chlorite, closely linked to microstructural observations, were performed in both the core and damage zones of the fault zone. Regardless of the microstructural position, chlorite from the damage zone contains iron and magnesium (Fetotal / (Fetotal + Mg) about 0.4), with Fe3+ accounting for about 30 % of the total iron. Chlorite in the core zone is enriched in total iron, but individual Fe3+/Fetotal ratios range from 15 % to 40 %, depending on the microstructural position of the grain. Homogeneous temperature conditions about 280–290 °C have been obtained by chlorite thermometry. A scenario is proposed for the evolution of fluid–rock interaction conditions at the scale of the fault zone. It involves the circulation of a single hydrothermal fluid with homogeneous temperature but several redox properties. A highly reducing fluid evolves due to redox reactions involving progressive dissolution of hematite, accompanied by crystallization of Fe2+-rich and Fe3+-rich chlorite in the core zone. This study shows the importance of determining the redox state of iron in chlorite to calculate their temperature of formations and to consider the fluid evolution at the scale of a fault.

Synergy between NiWO4 and chitosan for the development of catalysts for sulfide oxidation

In this work, catalysts based on composite films composed by chitosan with disordered NiWO4 (10, 20, and 40 % w/w) were synthesized for their application in the oxidation of sulfides to sulfones. The catalysts were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), optical profilometry, and contact angle measurements. Optimization of the catalytic conditions was performed using thioanisole as the standard molecule, resulting in optimal conditions of 50°C, 1 h, 10 mg catalyst loading, 8 equivalents of H2O2 as oxidant, and acetonitrile as solvent. The results obtained were superior to those with crystalline NiWO4 (highly ordered), highlighting the crystallinity of the system as a key factor in the development of new catalysts. The catalyst exhibited high stability over successive catalytic cycles, and scaling up to 50 times was achieved. Additionally, the reaction scope showed good conversion for a variety of different sulfides, indicating the robustness of the catalyst. Analysis of the catalytic mechanism through scavenger tests and spectroscopic probes revealed that reactive oxygen species (ROS) are responsible for the oxidation of sulfides to sulfones. Furthermore, it was observed that the synergy between NiWO4 and chitosan is crucial for the effective generation of ROS in this reaction.

Gravitational lensing reveals cool gas within 10-20 kpc around a quiescent galaxy

While quiescent galaxies have comparable amounts of cool gas in their outer circumgalactic medium (CGM) compared to star-forming galaxies, they have significantly less interstellar gas. However, open questions remain on the processes causing galaxies to stop forming stars and stay quiescent. Theories suggest dynamical interactions with the hot corona prevent cool gas from reaching the galaxy, therefore predicting the inner regions of quiescent galaxy CGMs are devoid of cool gas. However, there is a lack of understanding of the inner regions of CGMs due to the lack of spatial information in quasar-sightline methods. We present integral-field spectroscopy probing 10–20 kpc (2.4–4.8 Re) around a massive quiescent galaxy using a gravitationally lensed star-forming galaxy. We detect absorption from Magnesium (MgII) implying large amounts of cool atomic gas (108.4–109.3 M⊙ with T~104 Kelvin), in comparable amounts to star-forming galaxies. Lens modeling of Hubble imaging also reveals a diffuse asymmetric component of significant mass consistent with the spatial extent of the MgII absorption, and offset from the galaxy light profile. This study demonstrates the power of galaxy-scale gravitational lenses to not only probe the gas around galaxies, but to also independently probe the mass of the CGM due to it’s gravitational effect.

Study of Effects of Post-Weld Heat Treatment Time on Corrosion Behavior and Manufacturing Processes of Super Duplex Stainless SAF 2507 for Advanced Li-Ion Battery Cases.

Lithium-ion batteries are superior energy storage devices that are widely utilized in various fields, from electric cars to small portable electric devices. However, their susceptibility to thermal runaway necessitates improvements in battery case materials to improve their safety. This study used electrochemical analyses, including open-circuit potential (OCP), potentiodynamic polarization, and critical pitting temperature (CPT) analyses, to investigate the corrosion resistance of super duplex stainless steel (SAF 2507) applied to battery cases in relation to post-weld heat treatment (PWHT) time. The microstructure during the manufacture, laser welding, and PWHT was analyzed using field-emission scanning electron microscopy, X-ray diffraction, and electron backscatter diffraction, and the chemical composition was analyzed using dispersive X-ray spectroscopy and electron probe micro-analysis. The PWHT increased the volume fraction of austenite from 5% to 50% over 3 min at 1200 °C; this increased the OCP from -0.21 V to +0.03 V, and increased the CPT from 56 °C to 73 °C. The PWHT effectively improved the corrosion resistance, laying the groundwork for utilizing SAF 2507 in battery case materials. But the alloy segregation and heterogeneous grain morphology after PWHT needs improvement.

Glutathione and its structural modifications recognized by Raman Optical Activity and Circularly Polarized Luminescence

Raman Optical Activity combined with Circularly Polarized Luminescence (ROA-CPL) was used in the spectral recognition of glutathione peptide (GSH) and its model post-translational modifications (PTMs). We demonstrate the potential of ROA spectroscopy and CPL probes (EuCl3, Na3[Eu(DPA)3], NaEuEDTA) in the study of unmodified peptide, i.e. GSH, and its derivatives, i.e. glutathione oxidized (GSSG), S-acetylglutathione (GSAc) and S-nitrosoglutathione (GSNO). ROA spectral features of GSH, GSSG, and GSAc were determined along with thier changes upon the different pH conditions. Apart from the ROA, induced CPL signals of Eu(III) probes also proved to be sensitive to the structural modifications of GSH-based model PTMs, enabling their spectral recognition, especially by the NaEuEDTA probe.

Physical discovery in representation learning via conditioning on prior knowledge

Recent advances in electron, scanning probe, optical, and chemical imaging and spectroscopy yield bespoke data sets containing the information of structure and functionality of complex systems. In many cases, the resulting data sets are underpinned by low-dimensional simple representations encoding the factors of variability within the data. The representation learning methods seek to discover these factors of variability, ideally further connecting them with relevant physical mechanisms. However, generally, the task of identifying the latent variables corresponding to actual physical mechanisms is extremely complex. Here, we present an empirical study of an approach based on conditioning the data on the known (continuous) physical parameters and systematically compare it with the previously introduced approach based on the invariant variational autoencoders. The conditional variational autoencoder (cVAE) approach does not rely on the existence of the invariant transforms and hence allows for much greater flexibility and applicability. Interestingly, cVAE allows for limited extrapolation outside of the original domain of the conditional variable. However, this extrapolation is limited compared to the cases when true physical mechanisms are known, and the physical factor of variability can be disentangled in full. We further show that introducing the known conditioning results in the simplification of the latent distribution if the conditioning vector is correlated with the factor of variability in the data, thus allowing us to separate relevant physical factors. We initially demonstrate this approach using 1D and 2D examples on a synthetic data set and then extend it to the analysis of experimental data on ferroelectric domain dynamics visualized via piezoresponse force microscopy.

Investigation of microstructure and thermal expansion behaviour of a functionally graded YSZ/IN718 composite produced by laser-powder bed fusion

Yttria-stabilized zirconia (YSZ) has been extensively used as a thermal barrier coating (TBC) for high-temperature alloys. In this research, the microstructural attributes and thermal expansion behavior of an additively manufactured functionally graded composite (YSZ/IN718 FGC) were investigated. First, a powder mixture of IN718 and YSZ (ranging from 1 wt% to 4 wt%) was achieved via low-energy ball-milling at 100 rpm. Differential scanning calorimetry (DSC) analysis depicted the melting behaviour of the powder mixtures of different YSZ content. The endothermic peaks in the DSC curve, at ∼1360 ℃, suggested that the energy needed to melt the powder mixture increases with increasing YSZ content. These varying powder compositions were used to fabricate FGC samples using L-PBF. The study investigated the effects of laser power variation along the YSZ gradient, successfully mitigating the fusion defects that had been initially observed in FGC samples. Microscopic analyses, comprising scanning electron microscopy (SEM) and transmission electron microscopy (TEM), depicted the elemental segregation of Nb and Mo at the solidification subgrain boundaries (SSBs). Furthermore, the electron backscattered diffraction (EBSD) results demonstrated the refinement of grains and a reduction in textural intensity, particularly along the YSZ gradient. Energy dispersive spectroscopy (EDS) and electron probe micro analysis (EPMA) were used to validate the uniform dispersion of YSZ particles throughout the composite matrix, with the EPMA line scan affirming a predominantly linear YSZ content variation. Lastly, the coefficients of thermal expansion (CTEs) were evaluated, both parallel and perpendicular to the build direction. A decrease of approximately ∼6 % in CTE was noted along the building or gradation direction. Notably, perpendicular to the building direction, the CTE values for specimens containing 4 wt% and 2 wt% YSZ witnessed significant reductions of ∼32 % and ∼12 %, respectively. This research significantly contributes to the understanding of the microstructural intricacies and thermal behavior of YSZ/IN718 FGC produced by L-PBF process.

(Invited) Chemical Kinetic Method for Active-Site Quantification in Fe-N-C Catalysts and Correlation with Molecular Probe and Spectroscopic Site-Counting Methods

Heterogeneous catalysts consisting of iron cations incorporated into nitrogen-doped carbon (“Fe-N-C”) have received extensive attention as leading alternatives to Pt for the electrochemical oxygen reduction reaction (ORR). Fe-N-C catalysts host mononuclear nitrogen-ligated active centers, FeNx, that frequently coexist with agglomerated Fe species. Although FeNx are the dominant active centers for ORR and other electrocatalytic reactions, the relative accuracies of methods to quantify them are still debated. Here, we develop a kinetic probe-reaction approach to quantify FeNx centers and compare it with spectroscopic and molecular probe methods.Model Fe-N-C catalysts were synthesized to contain mononuclear FeNx species at low loadings (0.1–0.4 wt% bulk Fe) on solvent-accessible surfaces using a postsynthetic metalation approach and their Fe speciation was confirmed by low-temperature 57Fe Mössbauer spectroscopy. The initial rate of oxidation of a water-soluble hydroquinone molecule (per gcatalyst) catalyzed by these model materials correlates linearly with their density of FeNx centers, reflecting their intrinsic turnover frequency (TOF) for this reaction. This TOF, in turn, enables the estimation of the active-site density on any other Fe-N-C catalyst through a simple rate measurement. Kinetically determined FeNx site densities are measured on a suite of fourteen Fe-N-C catalysts with diverse synthetic origins and Fe speciation (0.3–8.4 wt% bulk Fe) and are compared with those estimated by low-temperature 57Fe Mössbauer spectroscopy, CO pulse chemisorption, and electrochemical stripping of NO derived from NO2 −. Kinetic quantifications of FeNx centers correlate well with those obtained from the CO pulse chemisorption method and Mössbauer spectroscopy. The broad survey of Fe-N-C materials also reveals the presence of outliers and challenges associated with each site quantification method. The kinetic method developed here does not require pretreatments that may alter active-site distributions nor specialized equipment beyond reaction vessels and standard analytical instrumentation, offering an attractive complementary approach. Figure 1

Noncovalent Interactions Steer the Formation of Polycyclic Aromatic Hydrocarbons.

Aromatic molecules play an important role in the chemistry of astronomical environments such as the cold interstellar medium (ISM) and (exo)planetary atmospheres. The observed abundances of (polycyclic) aromatic hydrocarbons such as benzonitrile and cyanonaphthalenes are, however, highly underestimated by astrochemical models. This demonstrates the need for more experimentally verified reaction pathways. The low-temperature ion-molecule reaction of benzonitrile•+ with acetylene is studied here using a multifaceted approach involving kinetics and spectroscopic probing of the reaction products. A fast radiative association reaction via an in situ experimentally observed prereactive complex shows the importance of noncovalent interactions in steering the pathway during cold ion-molecule reactions. Product structures of subsequent reactions are unambiguously identified using infrared action spectroscopy and reveal the formation of nitrogen-containing, linked bicyclic structures such as phenylpyridine•+ and benzo-N-pentalene+ structures. The results, contradicting earlier assumptions on the product structure, demonstrate the importance of spectroscopic probing of reaction products and emphasize the possible formation of linked bicyclic molecules and benzo-N-pentalene+ structures in astronomical environments.

Chiral Pair Density Waves with Residual Fermi Arcs in RbV3Sb5

Abstract The chiral 2 × 2 charge order has been reported and confirmed in the kagome superconductor RbV3Sb5, while its interplay with superconductivity remains elusive owing to its lowest superconducting transition temperature T C of about 0.85 K in the AV3Sb5 family (A = K, Rb, Cs) that severely challenges electronic spectroscopic probes. Here, utilizing dilution-refrigerator-based scanning tunneling microscopy down to 30 mK, we observe chiral 2 × 2 pair density waves with residual Fermi arcs in RbV3Sb5. We find a superconducting gap of 150 μeV with substantial residual in-gap states. The spatial distribution of this gap exhibits chiral 2 × 2 modulations, signaling a chiral pair density wave (PDW). Our quasi-particle interference imaging of the zero-energy residual states further reveals arc-like patterns. We discuss the relation of the gap modulations with the residual Fermi arcs under the space-momentum correspondence between PDW and Bogoliubov Fermi states.

Construction of Smart Coatings Containing Core-Shell Nanofibers with Self-Healing and Active Corrosion Protection.

With increasingly severe metal corrosion, coating preparation with high-performance corrosion protection has attracted more attention. Herein, the encapsulation of the corrosion inhibitor 8-hydroxyquinoline (8-HQ) as well as the self-healing agent linseed oil (LO) in polyvinyl alcohol (PVA) and chitosan (CS) shells were realized by coaxial electrospinning, which was recorded as PVA/CS@LO/8-HQ core-shell nanofibers. PVA/CS@LO/8-HQ nanofibers were employed to promote the high-performance corrosion protection of the epoxy coating. The anticorrosion mechanism was that the change of the local pH on the metal surface stimulated the release of 8-HQ from the nanofibers, which were then chelated with iron ions to form a complex. When cracks occurred and caused rupture of the nanofibers, LO was released and reacted with oxygen to cure them so that the cracks could be healed autonomously. The dynamic potential polarization curves showed that the corrosion inhibition efficiency of the compound inhibitor LO + 8-HQ reached 87.54%, 90.31%, and 85.57% at pH = 3, 7, and 11, respectively, higher than that of the single corrosion inhibitor. Density functional theory calculations revealed that the LO and 8-HQ combination, forming a hydrogen bond interaction, promoted the adsorption of inhibitors on the steel surface. Scanning Kelvin probe and electrochemical impedance spectroscopy proved the self-healing corrosion protection properties of the epoxy coating. These results demonstrated that embedding PVA/CS@LO/8-HQ nanofibers in the coating could obtain self-healing properties, and promote the mechanical and corrosion protection of epoxy coating.

Oxygen Functional Groups Regulate Cobalt‐Porphyrin Molecular Electrocatalyst for Acidic H2O2 Electrosynthesis at Industrial‐Level Current

AbstractElectrosynthesis of hydrogen peroxide (H2O2) based on proton exchange membrane (PEM) reactor represents a promising approach to industrial‐level H2O2 production, while it is hampered by the lack of high‐efficiency electrocatalysts in acidic medium. Herein, we present a strategy for the specific oxygen functional group (OFG) regulation to promote the H2O2 selectivity up to 92 % in acid on cobalt‐porphyrin molecular assembled with reduced graphene oxide. In situ X‐ray adsorption spectroscopy, in situ Raman spectroscopy and Kelvin probe force microscopy combined with theoretical calculation unravel that different OFGs exert distinctive regulation effects on the electronic structure of Co center through either remote (carboxyl and epoxy) or vicinal (hydroxyl) interaction manners, thus leading to the opposite influences on the promotion in 2e− ORR selectivity. As a consequence, the PEM electrolyzer integrated with the optimized catalyst can continuously and stably produce the high‐concentration of ca. 7 wt % pure H2O2 aqueous solution at 400 mA cm−2 over 200 h with a cell voltage as low as ca. 2.1 V, suggesting the application potential in industrial‐scale H2O2 electrosynthesis.

Oxygen Functional Groups Regulate Cobalt-Porphyrin Molecular Electrocatalyst for Acidic H2O2 Electrosynthesis at Industrial-Level Current.

Electrosynthesis of hydrogen peroxide (H2O2) based on proton exchange membrane (PEM) reactor represents a promising approach to industrial-level H2O2 production, while it is hampered by the lack of high-efficiency electrocatalysts in acidic medium. Herein, we present a strategy for the specific oxygen functional group (OFG) regulation to promote the H2O2 selectivity up to 92 % in acid on cobalt-porphyrin molecular assembled with reduced graphene oxide. In situ X-ray adsorption spectroscopy, in situ Raman spectroscopy and Kelvin probe force microscopy combined with theoretical calculation unravel that different OFGs exert distinctive regulation effects on the electronic structure of Co center through either remote (carboxyl and epoxy) or vicinal (hydroxyl) interaction manners, thus leading to the opposite influences on the promotion in 2e- ORR selectivity. As a consequence, the PEM electrolyzer integrated with the optimized catalyst can continuously and stably produce the high-concentration of ca. 7 wt % pure H2O2 aqueous solution at 400 mA cm-2 over 200 h with a cell voltage as low as ca. 2.1 V, suggesting the application potential in industrial-scale H2O2 electrosynthesis.

Photoluminescence Spectroscopy Sheds New Light on Silicon Microchip Functional Properties.

In this study, we demonstrate that photoluminescence spectroscopy probing local interaction and dynamics at the fundamental level is a versatile tool for testing and evaluation of semiconducting materials as well as microscale chips based on them. Monocrystalline silicon, which is still an undisputed leader among semiconductors in microelectronics, exhibits very low photoluminescence emission additionally shielded by the metallization and passivating layers at the integrated circuit level. To unleash the full potential of photoluminescence spectroscopy for advanced testing and evaluation of the functional properties of the silicon microchips, new essential conceptually built approaches are required that overcome this problem. Here, we report on the first fundamental research-based application of a potentiometric dye to sense the electric field of operational silicon chips. Furthermore, we demonstrate high sensitivity of crystalline silicon phonon-assisted photoluminescence to local temperature in the 27-64 °C range. Our results show that sensing and mapping of thermal and electric field distributions using photoluminescence can enable precision testing of the structure, function, operation, and security, not only at the component level but also at the level of the entire integrated circuit.

Reversible Raman D-band changes: A new probe into the pressure-induced collapse of carbon nanotubes

The control of the geometry of carbon nanotubes has a high potential for electro-optical technology developments. We report here the use of a new spectroscopic signature for the detection and characterization of the pressure induced radial buckling of single walled carbon nanotubes using Raman spectroscopy combined with sapphire anvil cell pressure systems. We follow the appearance of a defect-free Raman D-band contribution in bundled samples which is assigned to the pressure-induced radial buckling, as already shown on radially collapsed nanotubes at ambient pressure. On pressure release, this contribution to the D-band disappears, confirming the reversibility of the process. We applied this approach to the study of isolated tubes and followed the collapse transition of a 1.7 nm diameter tube, most likely identified as a (16,8) chirality, starting at 1 GPa and ending at 2 GPa. Our study further illustrates the potential of utilizing the D-band as a new spectroscopic probe to explore geometrical changes in carbon nanotubes.

Investigating the influence of cerium doping on the structural, optical and electrical properties of ZnNiMgFe2-xCexO4 soft ferrites

The present work reports the optical, structural, and electrical properties of cerium-doped Zn0.6Ni0.2Mg0.2Fe2-xCexO4 soft ferrites by green synthesis method that unwrap transformative insights and find technological applications through X-ray diffraction (XRD), UV visible spectroscopy and IV-point probe techniques. Ferrites with different cerium concentrations (x = 0.0, 0.0250, 0.0375) show an enormous difference in the optical, structural, and electrical behavior of the ferrites. The crystallite size increases to 46.9 nm, with a concomitant increase in lattice constants up to 8.550 Å for x = 0.0375. A similar structural shift was noticed in X-ray and bulk densities from 5.031 to 4.982 g/cm³ and 3.83 to 3.97 g/cm³, respectively. The optical explorations revealed a remarkable bandgap reduction from 2.768 eV to 2.758 eV improving the utility of the material substantially in magneto-optic devices. Conversely, the refractive index increases from 2.420 to 2.423, and the imaginary dielectric constant goes up from 10.654 to 10.667, giving a herald of advancement in photonic technologies. Electrically, the study marks a drastic reduction in DC resistivity from 1.95 × 105 to 6.13 × 103 ohm-cm with the Ce doping, which indicates higher conductivity suitable for telecommunication. This extensive work on Ce-doped soft ferrites now opens up newer avenues of applications in electronics and magneto-optics, blending scientific inquiry with practical utility.

Aqueous PEIE Soaking on ZnO for Ultraviolet Light Activation-Free Organic Photovoltaic Modules.

Ultraviolet (UV) light is typically needed to activate inverted organic photovoltaics (OPVs) with zinc oxide (ZnO) as electron transporting layer (ETL)for higher efficiency. However, UV light is a major cause for the degradation of organic active layers in OPVs. This is a contradiction that UV light activation enhances the efficiency but UV illumination deteriorates the stability. It is important to solve this contradiction to develop UV light activation-free OPV devices. Herein, a method of aqueous polyethylenimine ethoxylated (PEIE) soaking on ZnO is reported to realize UV light activation-free OPV devices. The S-shape in current density-voltage (J-V) characteristics of devices tested without UV light activation is eliminated through the treatment of aqueous PEIE soaking on ZnO. The treatment reduces the oxygen adsorbates, which is confirmed by Kelvin probe and X-ray photoelectron spectroscopy. A 10.08 cm2 organic photovoltaic module with the treated ZnO asETL showed high photovoltaic performance: VOC = 5.68 V, JSC = 2.7 mAcm-2, FF = 75.1%, and POutput = 11.5 mWcm-2 tested with the UV filter (light intensity of 0.788 sun). UV light activation is not needed for the modules to obtain high efficiency.

Noncanonical Amino Acids in Biocatalysis.

In recent years, powerful genetic code reprogramming methods have emerged that allow new functional components to be embedded into proteins as noncanonical amino acid (ncAA) side chains. In this review, we will illustrate how the availability of an expanded set of amino acid building blocks has opened a wealth of new opportunities in enzymology and biocatalysis research. Genetic code reprogramming has provided new insights into enzyme mechanisms by allowing introduction of new spectroscopic probes and the targeted replacement of individual atoms or functional groups. NcAAs have also been used to develop engineered biocatalysts with improved activity, selectivity, and stability, as well as enzymes with artificial regulatory elements that are responsive to external stimuli. Perhaps most ambitiously, the combination of genetic code reprogramming and laboratory evolution has given rise to new classes of enzymes that use ncAAs as key catalytic elements. With the framework for developing ncAA-containing biocatalysts now firmly established, we are optimistic that genetic code reprogramming will become a progressively more powerful tool in the armory of enzyme designers and engineers in the coming years.