Thienylquinonoidal Porphyrins and Hexaphyrins with Singlet Diradical Ground States.

To explore stable organic diradicaloids, meso-thienylquinonoid-substituted porphyrins Pn and hexaphyrins Hn, where "n" denotes the number of thienyl units in the meso-substituents, were synthesized. P0 was identified as a closed-shell quinonoid, whereas P1 was shown to possess significant diradical character with diradical character index (y) of 0.99 and quite small singlet-triplet energy gap (ΔES-T ) of -0.13 kcal mol-1 . P1 was certainly stable, allowing its isolation, but decomposed gradually in solution. In the hexaphyrin series, it was shown that H0 and H1 were closed-shell quinonoids, but H2 was a highly stable diradicaloid with y=0.85 and ΔES-T of -3.72 kcal mol-1 . The high stability of H2 was ascribed to effective spin delocalization over the entire conjugated network. Characteristically, H2 displays an intense absorption band in NIR region at λmax =1175 nm with molar absorption coefficient (ϵ) of 8.81×104  mol-1 L cm-1 , a narrow HOMO-LUMO gap of 0.69 eV, and nine reversible redox potential waves.

Push-Pull-Type Polychlorotriphenylmethyl Radicals: New Two-Photon Absorbers and Dyes for Generation of Photo-Charges.

Tri(4-iodo-2,3,5,6-tetrachlorophenyl)methane (2) is reported as a general building block for the synthesis of various π-conjugated polychlorotriphenylmethyl (PTM) radicals. Three push-pull-type triphenylamine-substituted PTM radicals with different substitution patterns were prepared and all exhibited intense inter-valence charge-transfer bands and large two-photon absorption (TPA) cross sections. Moreover, increase of solvent polarity also resulted in improved TPA response. The charge-transfer character of the relevant excited states provoked the efficient photo-generation of charges, anions in the PTM and cations in the amine arms, driven by the amphoteric redox character and the small coupling between donor and acceptor.

Stable 3,6-Linked Fluorenyl Radical Oligomers with Intramolecular Antiferromagnetic Coupling and Polyradical Characters.

Organic radicals display unique physical structures and could become next generation functional materials. However, design and synthesis of stable neutral radicals with a significant polyradical character has been an enormous challenge for chemists. In this work, we synthesized a series of stable 3,6-linked, kinetically blocked fluorenyl radical oligomers up to hexamer (FR-n, n = 1-6). Their ground-state geometric and electronic structures were systematically studied by various experimental methods including X-ray crystallographic analysis, variable temperature nuclear magnetic resonance, electron spin resonance, and superconducting quantum interference device measurements, supported by density functional theory and ab initio calculations. Moderate antiferromagnetic coupling between the fluorenyl radicals was observed, and moderate to large diradical and polyradical characters were calculated from dimer onward. Furthermore, their photophysical properties were estimated by steady-state, transient absorption, and two-photon absorption measurements, and their electrochemical properties were investigated by cyclic voltammetry/differential pulse voltammetry and spectro-electrochemical measurements. A clear chain length dependence of their optical, electrochemical, and magnetic properties was found for the oligomers with an odd or even number of spin centers, respectively.

Doubly N-Fused [24]Pentaphyrin Silicon Complex and Its Fluorosilicate: Enhanced Möbius Aromaticity in the Fluorosilicate.

Treatment of nonaromatic N-fused [24]pentaphyrin with trichloromethylsilane in the presence of a base afforded doubly N-fused [24]pentaphyrin and its silicon complex. Addition of fluoride ion to the silicon complex led to the formation of its fluorosilicate as an unprecedented monoanionic six-coordinated SiIV complex of porphyrinoid. Treatment of the fluorosilicate with acid led to the recovery of the silicon complex. The doubly N-fused pentaphyrin, the silicon complex, and the fluorosilicate were all characterized as distinct Möbius aromatic molecules by spectroscopic measurements and X-ray crystallographic analyses. Importantly, the second N-fusion reaction, Si-incorporation and fluoride addition to the Si-atom enhanced the aromaticity of doubly N-fused [24]pentaphyrins in this order. Tamao-Fleming oxidation of the silicon complex gave ß-keto doubly N-fused pentaphyrin and triply fused [24]pentaphyrin, which were nonaromatic and Hückel anti-aromatic, respectively.

ß-to-ß 2,5-Pyrrolylene-Linked Cyclic Porphyrin Oligomers.

ß-to-ß 2,5-Pyrrolylene linked cyclic porphyrin oligomers have been synthesized by Suzuki-Miyaura coupling of 2,5-diborylpyrrole and 3,7-dibromoporphyrin. The cyclic porphyrin oligomers exhibit roughly coplanar structures, strong excitonic coupling, small electrochemical HOMO-LUMO gaps, and ultrafast excitation energy transfer between the neighboring porphyrins via the pyrrolylene bridge.

Morphological and Structural Evolutions of Metal-Organic Framework Particles from Amorphous Spheres to Crystalline Hexagonal Rods.

Compositions as well as morphologies and structures of particles are vital factors that define their properties and applications. However, the morphology and structure changes associated with the composition change of metal-organic frameworks (MOFs) are barely studied. Herein, we report the morphology and structure changes of MOF particles associated with the ratio of two organic linkers incorporated within MOF particles, when they are constructed from the reactions of In(NO3)3 in the presence of isophthalic acid (H2IPA) and/or 1,4-benzenedicarboxylic acid (H2BDC). Two tendencies­the tendency of BDC and In(3+) to form porous crystalline hexagonal rods, and the tendency of IPA and In(3+) to form non-porous amorphous spherical particles­compete during the formation of MOF particles. Eventually, the incorporated ratio of BDC and IPA within the MOF particles, and thus their morphology and porosity, are controlled by altering the relative amounts of H2BDC and H2IPA used during the reactions.

Enhanced transmission due to antireflection coating layer at surface plasmon resonance wavelengths.

We present experiments and analysis on enhanced transmission due to dielectric layer deposited on a metal film perforated with two-dimensional periodic array of subwavelength holes. The Si3N4 overlayer is applied on the perforated gold film (PGF) fabricated on GaAs substrate in order to boost the transmission of light at the surface plasmon polariton (SPP) resonance wavelengths in the mid- and long-wave IR regions, which is used as the antireflection (AR) coating layer between two dissimilar media (air and PGF/GaAs). It is experimentally shown that the transmission through the perforated gold film with 1.8 µm (2.0 µm) pitch at the first-order (second-order) SPP resonance wavelengths can be increased up to 83% (110%) by using a 750 nm (550 nm) thick Si3N4 layer. The SPP resonance leads to a dispersive resonant effective permeability (µeff ≠ 1) and thereby the refractive index matching condition for the conventional AR coating on the surface of a dielectric material cannot be applied to the resonant PGF structure. We develop and demonstrate the concept of AR condition based on the effective parameters of PGF. In addition, the maximum transmission (zero reflection) condition is analyzed numerically by using a three-layer model and a transfer matrix method is employed to determine the total reflection and transmission. The numerically calculated total reflection agrees very well with the reflection obtained by 3D full electromagnetic simulations of the entire structure. Destructive interference conditions for amplitude and phase to get zero reflection are well satisfied.

Effect analysis of design variables on the disc in a double-eccentric butterfly valve.

We have performed a shape optimization of the disc in an industrial double-eccentric butterfly valve using the effect analysis of design variables to enhance the valve performance. For the optimization, we select three performance quantities such as pressure drop, maximum stress, and mass (weight) as the responses and three dimensions regarding the disc shape as the design variables. Subsequently, we compose a layout of orthogonal array (L16) by performing numerical simulations on the flow and structure using a commercial package, ANSYS v13.0, and then make an effect analysis of the design variables on the responses using the design of experiments. Finally, we formulate a multiobjective function consisting of the three responses and then propose an optimal combination of the design variables to maximize the valve performance. Simulation results show that the disc thickness makes the most significant effect on the performance and the optimal design provides better performance than the initial design.

Lateral heterostructures of WS2 and MoS2 monolayers for photo-synaptic transistor.

Von Neumann architecture-based computing, while widely successful in personal computers and embedded systems, faces inherent challenges including the von Neumann bottleneck, particularly amidst the ongoing surge of data-intensive tasks. Neuromorphic computing, designed to integrate arithmetic, logic, and memory operations, has emerged as a promising solution for improving energy efficiency and performance. This approach requires the construction of an artificial synaptic device that can simultaneously perform signal processing, learning, and memory operations. We present a photo-synaptic device with 32 analog multi-states by exploiting field-effect transistors based on the lateral heterostructures of two-dimensional (2D) WS2 and MoS2 monolayers, formed through a two-step metal-organic chemical vapor deposition process. These lateral heterostructures offer high photoresponsivity and enhanced efficiency of charge trapping at the interface between the heterostructures and SiO2 due to the presence of the WS2 monolayer with large trap densities. As a result, it enables the photo-synaptic transistor to implement synaptic behaviors of long-term plasticity and high recognition accuracy. To confirm the feasibility of the photo-synapse, we investigated its synaptic characteristics under optical and electrical stimuli, including the retention of excitatory post-synaptic currents, potentiation, habituation, nonlinearity factor, and paired-pulse facilitation. Our findings suggest the potential of versatile 2D material-synapse with a high density of device integration.

Heteronanostructured Field-Effect Transistors for Enhancing Entropy and Parameter Space in Electrical Unclonable Primitives.

Hardware security is not a new problem but is ever-growing in consumer and medical domains owing to hyperconnectivity. A physical unclonable function (PUF) offers a promising hardware security solution for cryptographic key generation, identification, and authentication. However, electrical PUFs using nanomaterials or two-dimensional (2D) transition metal dichalcogenides (TMDCs) often have limited entropy and parameter space sources, both of which increase the vulnerability to attacks and act as bottlenecks for practical applications. We report an electrical PUF with enhanced entropy as well as parameter space by incorporating 2D TMDC heteronanostructures into field-effect transistors (FETs). Lateral heteronanostructures of 2D molybdenum disulfide and tungsten disulfide serve as a potent entropy source. The variable feature of FETs is further leveraged to enhance the parameter space that provides multiple challenge-response pairs, which are essential for PUFs. This combination results in stably repeatable yet highly variable FET characteristics as alternative electrical PUFs. Comprehensive PUF performance analyses validate the bit uniformity, reproducibility, uniqueness, randomness, false rates, and encoding capacity. The 2D material heteronanostructure-driven electrical PUFs with strong FET-to-FET variability can potentially be augmented as an immediately deployable and scalable security solution for various hardware devices.

Analysis of subwavelength metal hole array structure for the enhancement of back-illuminated quantum dot infrared photodetectors.

This paper is focused on analyzing the impact of a two-dimensional metal hole array structure integrated to the back-illuminated quantum dots-in-a-well (DWELL) infrared photodetectors. The metal hole array consisting of subwavelength-circular holes penetrating gold layer (2D-Au-CHA) provides the enhanced responsivity of DWELL infrared photodetector at certain wavelengths. The performance of 2D-Au-CHA is investigated by calculating the absorption of active layer in the DWELL structure using a finite integration technique. Simulation results show that the performance of the DWELL focal plane array (FPA) is improved by enhancing the coupling to active layer via local field engineering resulting from a surface plasmon polariton mode and a guided Fabry-Perot mode. Simulation method accomplished in this paper provides a generalized approach to optimize the design of any type of couplers integrated to infrared photodetectors. Experimental results demonstrate the enhanced signal-to-noise ratio by the 2D-Au-CHA integrated FPA as compared to the DWELL FPA. A comparison between the experiment and the simulation shows a good agreement.

Highly Sensitive and Cost-Effective Polymeric-Sulfur-Based Mid-Wavelength Infrared Linear Polarizers with Tailored Fabry-Pérot Resonance.

Inverse-vulcanized polymeric sulfur has received considerable attention for application in waste-based infrared (IR) polarizers with high polarization sensitivities, owing to its high transmittance in the IR region and thermal processability. However, there have been few reports on highly sensitive polymeric sulfur-based polarizers by replication of pre-simulated dimensions to achieve a high transmission of the transverse magnetic field (TTM ) and extinction ratio (ER). Herein, a 400-nanometer-pitch mid-wavelength infrared bilayer linear polarizer with self-aligned metal gratings is introduced on polymeric sulfur gratings integrated with a spacer layer (SM-polarizer). The dimensions of the SM-polarizer can be closely replicated using pre-simulated dimensions via a systematic investigation of thermal nanoimprinting conditions. Spacer thickness is tailored from 40 to 5100 nm by adjusting the concentration of polymeric sulfur solution during spin-coating. A tailored spacer thickness can maximize TTM in the broadband MWIR region by satisfying Fabry-Pérot resonance. The SM-polarizer yields TTM of 0.65, 0.59, and 0.43 and ER of 3.12 × 103 , 5.19 × 103 , and 5.81 × 103 at 4 µm for spacer thicknesses of 90, 338, and 572 nm, respectively. This demonstration of a highly sensitive and cost-effective SM-polarizer opens up exciting avenues for infrared polarimetric imaging and for applications in polarization manipulation.

Supraglottic airway device and venoarterial extracorporeal membrane oxygenation support for curative surgery in a patient with huge thyroid mass: A case report.

In the case of complete surgical resection of locally aggressive thyroid mass with severely compromised airways, airway management is difficult and can be considerably risky. We report a case of airway management using i-gel™ and cardiopulmonary bypass (CPB) with venoarterial extracorporeal membrane oxygenation (ECMO), which is a safe and feasible method of airway management for providing general anesthesia in a patient with a large thyroid mass.

The Effects of Remifentanil and Fentanyl on Emergence Agitation in Pediatric Strabismus Surgery.

Emergence agitation (EA) is one of the main concerns in the field of pediatric anesthesia using sevoflurane. We investigated the effects of remifentanil and fentanyl on the incidence of EA in pediatric patients undergoing strabismus surgery. Ninety children were randomly allocated into two groups and received either remifentanil (group R: intraoperatively remifentanil 0.2 µg/kg/min) or fentanyl (group F: fentanyl 2 µg/kg at anesthetic induction) intraoperatively. After surgery, EA incidence was assessed using a four-point agitation scale and Pediatric Anesthesia Emergence Delirium (PAED) scale in the post-anesthesia care unit. Face, leg, activity, cry, and consolability (FLACC) scores for postoperative pain were also assessed. The incidence of EA using the four-point agitation scale (scores ≥ 3) was similar in both groups (remifentanil group, 28.89% vs. fentanyl group, 24.44%). Similar results were obtained using the PAED scale (scores > 12), with an incidence of 33.33% in the remifentanil group and 26.67% in the fentanyl group. Differences in FLACC scores were not found to be statistically significant. A single bolus administration of fentanyl during anesthetic induction and continuous infusion of remifentanil during surgery had similar effects on the EA incidence in these pediatric patients.

A retrospective study of changes in skin cancer characteristics over 11 years.

BACKGROUND: The incidence of skin cancer, which is primarily caused by exposure to ultraviolet radiation, has steadily increased in recent years. The authors of the present study sought to investigate changes in the epidemiology of skin cancer by conducting a retrospective review of patients diagnosed with skin cancer who received related care at a single medical institution.
. METHODS: The present study included patients who were diagnosed with skin cancer and received treatment at Gyeongsang National University Hospital from 2008 to 2018. The site and type of skin cancer, the number of patients with skin cancer each year, the sex and sex ratio of the patients, and changes in patients' age at first diagnosis were examined through retrospective chart reviews.
. RESULTS: The number of patients with skin cancer significantly increased, but statistically significant changes were not found in patients' sex, skin cancer sites, or the types of skin cancer. However, patients' age at the first diagnosis of skin cancer showed a statistically significant decrease starting in 2015.
. CONCLUSION: In this study, the number of patients with skin cancer increased over time. However, patients' age at first diagnosis has decreased since 2015. Therefore, younger patients should take care to prevent skin cancer, and further research on the causes of skin cancer in younger patients is needed.

Plasmonic-Layered InAs/InGaAs Quantum-Dots-in-a-Well Pixel Detector for Spectral-Shaping and Photocurrent Enhancement.

The algorithmic spectrometry as an alternative to traditional approaches has the potential to become the next generation of infrared (IR) spectral sensing technology, which is free of physical optical filters, and only a very small number of data are required from the IR detector. A key requirement is that the detector spectral responses must be engineered to create an optimal basis that efficiently synthesizes spectral information. Light manipulation through metal perforated with a two-dimensional square array of subwavelength holes provides remarkable opportunities to harness the detector response in a way that is incorporated into the detector. Instead of previous experimental efforts mainly focusing on the change over the resonance wavelength by tuning the geometrical parameters of the plasmonic layer, we experimentally and numerically demonstrate the capability for the control over the shape of bias-tunable response spectra using a fixed plasmonic structure as well as the detector sensitivity improvement, which is enabled by the anisotropic dielectric constants of the quantum dots-in-a-well (DWELL) absorber and the presence of electric field along the growth direction. Our work will pave the way for the development of an intelligent IR detector, which is capable of direct viewing of spectral information without utilizing any intervening the spectral filters.

Reconstruction of nasal ala and tip following skin cancer resection.

BACKGROUND: Defects of the nasal ala and tip have a complex three-dimensional structure that makes them challenging to reconstruct. Many reconstructive options have been described for nasal ala and tip defects, ranging from primary closure to local flaps and skin grafts. However, it is difficult to determine which method will yield the best cosmetic results in each individual case. Thus, the purpose of this study was to determine which surgical procedures for reconstructing defects of the nasal ala and tip have better cosmetic results. METHODS: From 2008 to 2018, 111 patients underwent surgery to reconstruct skin defects after resection of skin cancer in the nasal ala or tip. Their charts were reviewed to obtain data on age, sex, surgical location, size of the defect, surgical method, and cosmetic results using a visual analog scale (VAS). RESULTS: For nasal ala reconstruction, the most commonly used surgical technique was the nasolabial flap (n= 42). This method also had the highest VAS score (7/10). The most commonly selected surgical method for nasal tip reconstruction was the bilobed flap (n= 13), and bilobed flaps and primary closure had the highest VAS score (7/10). CONCLUSION: Nasolabial flaps showed excellent cosmetic results for the reconstruction of nasal ala defects, while primary closure and bilobed flaps yielded excellent cosmetic results for the reconstruction of nasal tip defects.

Immediate regraft of the remnant skin on the donor site in split-thickness skin grafting.

BACKGROUND: Skin defects of head and neck need reconstruction using various local flaps. In some cases, surgeons should consider skin graft for large skin defect. It is important to heal skin graft and donor sites. The authors investigated wound healing mechanisms at the donor sites with split-thick-ness skin graft (STSG). In this study, the authors compared two types of immediate regraft including sheets and islands for the donor site after facial skin graft using remnant skin. METHODS: The author reviewed 10 patients who underwent STSG, from March 2015 to May 2017, for skin defects in the craniofacial area. The donor site was immediately covered with the two types using remnant skin after harvesting skin onto the recipient site. Depending on the size of the remnant skin, we conducted regraft with the single sheet (n= 5) and island types (n= 5). RESULTS: On postoperative day 1 and 3 months, the scar formation was evaluated using the Patient and Observer Scar Assessment Scale (POSAS) and Vancouver Scar Scale (VSS). Total POSAS and VSS scores for the island type were lower than in single sheet group after 3 months postoperatively. There was significant difference in specific categories of POSAS and VSS. CONCLUSION: This study showed a reduction in scar formation following immediate regrafting of the remnant skin at the donor site after STSG surgery. Particularly, the island type is useful for clinical application to facilitate healing of donor sites with STSG.

Near-Infrared S2 Fluorescence from Deprotonated Möbius Aromatic [32]Heptaphyrin.

This study revealed S2 fluorescence from deprotonated meso-pentafluorophenyl-substituted Möbius aromatic [32]heptaphyrin(1.1.1.1.1.1.1) that was formed upon treatment of neutral antiaromatic [32]heptephyrin with tetrabutylammonium fluoride. Higher excited-state dynamics and emission were studied by fs-transient absorption spectroscopy and a broad-band fluorescence upconversion technique. This is the first S2 fluorescence from chromophores with twisted Möbius topology, and the observation of S2 fluorescence in the near-infrared region has been unprecedented. The higher excited-state dynamics of neutral and deprotonated [32]heptaphyrins were compared by ultrafast transient absorption spectroscopy to understand the S2 fluorescence origin. In the antiaromatic [32]heptaphyrin, a fast time component of 65 fs was assigned as an internal conversion process from the SB state to the SQ state, which occurs prior to relaxation to the optically dark, lowest electronic state (SD). Therefore, the SQ state of the antiaromatic [32]heptaphyrin acts as a trap state intervening radiative transitions from the SB state to the S0 state. In deprotonated [32]heptaphyrin, the internal conversion from the SB state to the SQ state proceeds with a slower time constant of 150 fs for owing to its rigid structure, helping the observation of its S2 fluorescence.

Role of Disorder in the Extent of Interchain Delocalization and Polaron Generation in Polythiophene Crystalline Domains.

To understand how disorder within conjugated polymer aggregates influences the polaron generation process, we investigated poly(3-hexylthiophene) (P3HT) and a congeneric random copolymer incorporating 33 mol % substituent-free thiophene units (RP33). Steady-state absorption and fluorescence spectra showed that increasing the intrachain torsional disorder in aggregates increases the energy and breadth of the density of states (DOS). By extracting polaron dynamics in the transient absorption spectra, we found that an activation energy barrier of 0.05 eV is imposed on the charge separation process in P3HT, whereas that in RP33 is essentially barrierless. We also found that a significant amount of excitons in P3HT are deactivated by traps, while no trapped excitons are generated in RP33. This efficient polaron generation in RP33 was attributed to the excess energy and enhanced interchain delocalization of precursor states provided by the intrachain torsional disorder and the close-packing structure in the absence of hexyl substituents.