Search

We illustrate a technique by which heterodyne-detected sum-frequency generation spectroscopy is performed at multiple angles of incidence in order to decompose components of the second-order susceptibility tensor when all beams are polarized parallel to the plane of incidence. As an illustration, we study the non-vibrationally resonant gold response. We benchmark our results by comparing with measurements obtained in a polarization scheme that isolates a single element of the susceptibility tensor. Our technique is particularly valuable in the case of metal substrates, where the surface selection rule often prevents spectra from being acquired in multiple beam polarizations. [ABSTRACT FROM AUTHOR]

Background: The aim of this study was to estimate the relationship between arterial stiffness and components of metabolic syndrome (MetS) in different age- and gender groups.Methods: A total of 12,900 Chinese adults aged 20-79 years were recruited and stratified on the basis of gender and age. All participants underwent the measurement of waist circumference, blood pressure (BP), brachial-ankle pulse wave velocity (baPWV; an indicator of arterial stiffness), and blood chemistry. Multiple linear regression analysis was performed to evaluate the relationship between baPWV and above variables, to determine the relative influence of each component of MetS on baPWV.Results: The prevalence of metabolic disorders except for low high-density lipoprotein cholesterol (HDL-C) was much higher in men than in women. All participants with MetS or any component of MetS except for low HDL-C had higher baPWV. BP was positively correlated with baPWV in all groups, while HDL-C was not correlated with baPWV in any groups. In addition, fasting glucose was related to baPWV in middle-aged adults and the elderly. Waist circumference had a positive association with baPWV in middle-aged adults and young men, triglyceride levels showed a significant correlation with baPWV in middle-aged women and young men. Of the MetS components, elevated BP was the strongest predictor of baPWV.Conclusion: The prevalence of metabolic disorders and the association between baPWV and metabolic variables are dependent on age and gender. Different components of MetS exert distinct impacts on the baPWV in different age- and gender groups, with BP being the strongest predictor. It is suggested that age and gender should be taken into accounted in the management of MetS aiming to reduce subsequent complications.

Conjugated polymers are of great interest owing to their potential in stretchable electronics to function under complex deformation conditions. To improve the performance of conjugated polymers, various structural designs have been proposed and these conjugated polymers are specially applied in exotic optoelectronics. In this work, a series of all‐conjugated block copolymers (PII2T‐b‐PNDI2T) comprising poly(isoindigo–bithiophene) (PII2T) and poly(naphthalenediimide–bithiophene) (PNDI2T) are developed with varied compositions and applied to electret‐free phototransistor memory. Accordingly, these memory devices present p‐type transport capability and electrical‐ON/photo‐OFF memory behavior. The efficacy of the all‐conjugated block copolymer design in improving the memory‒photoresponse properties in phototransistor memory is revealed. By optimizing the composition of the block copolymer, the corresponding device achieves a wide memory window of 36 V and a high memory ratio of 7 × 104. Collectively, the results of this study indicate a new concept for designing electret‐free phototransistor memory by using all‐conjugated block copolymer heterojunctions to mitigate the phase separation of conjugated polymer blends. Meanwhile, the intrinsic optoelectronic properties of the constituent conjugated polymers can be well‐maintained by using an all‐conjugated block copolymer design. [ABSTRACT FROM AUTHOR]

Photosynaptic transistor is considered to be a potential candidate for breaking the von Neumann bottleneck in photo‐communication field. Herein, a series of donor−acceptor type and crosslinked core−shell nanoparticles are designed and applied in phototransistors as a charge‐trapping electret. The outer shell is composed of poly(ethylene glycol) methyl ether methacrylate (PEGMA); while the inner core comprises donors of thiophene and bithiophene (2T) and acceptors of benzothiazole (BT), naphthalenediimide (NDI), and hexafluorobenzene‐naphthalenediimide (FB‐NDI). It is found that the core−shell and donor−acceptor design play an important role in the charge trapping, photoresponse, and the corresponding device performance. Accordingly, the phototransistor comprising the crosslinked core−shell nanoparticles with a donor of 2T and an acceptor of BT (PV2T‐BT) produced the highest memory ratio of 105 over 104 s at a high operating voltage of −40 V. Meanwhile, the same device presented the highest paired‐pulse facilitation ratio of 168% at a medium operating voltage of −1 V, and an ultra‐low energy consumption of 0.0324 fJ at a low operating voltage of −1 µV. The findings in this study provide a new perspective on material design for phototransistor devices. [ABSTRACT FROM AUTHOR]

Vibrational sum-frequency generation (SFG) spectroscopy can provide valuable qualitative and quantitative information about molecular species at surface and buried interfaces. For example, the resonance frequency of a particular chemical function group is revealing of the surface environment, especially when compared to what is observed in bulk IR absorption or Raman scattering spectra. Furthermore, the amplitude of the mode can be related to the molecular orientation, providing a detailed quantitative account of the surface structure. Each of these attributes, however, requires fitting the spectra to some vibrationally resonant line shape. This is particularly challenging when the modes of interest co-exist with broad resonance features, such as water O–H stretching. In this perspective, we examine the merits and consequences of different approaches to fitting homodyne SFG data. We illustrate that, while any model can provide a useful description of the data, no model can accurately and consistently provide even the relative phase deeply encoded in homodyne data without the use of additional information. [ABSTRACT FROM AUTHOR]

Rod‐like molecules with liquid crystalline phase transitions show highly ordered stacking and orientation, which is promising as the floating gate electret in high‐performance photonic field‐effect transistor (FET) memory. In this work, a series of rod‐like molecules, alkyl‐dinaphtho[2,3‐b:2′,3′‐f]thieno[3,2‐b]thiophene (Cn‐DNTT), are investigated with a smectic liquid crystalline phase transition. The photonic FET memory featuring these rod‐like molecules is correlated with their morphology and crystallographic properties. A volatility transition from short−term to long−term memory behavior is found by utilizing the smectic liquid crystalline phase transitions (SmX, X = H, K, E) to orient the stacking in the floating gate. Accordingly, the annealed 2,9‐didecyldinaphtho[2,3‐b:2′,3′‐f]thieno[3,2‐b]thiophene (C10‐DNTT) polycrystalline film with the optimized alkyl chain length achieved preferential end‐on orientation associated with the herringbone‐type stacking to store charges during photowriting, along with effective charge tunneling for the trapped charges during electrical erasing. Therefore, the resultant photonic FET memory provided a superior ON/OFF current ratio of up to 105 with retention of 104 after 104 s. The results demonstrate that rod‐like molecules with smectic liquid crystalline phase and highly ordered orientation have great potentials for developing high‐performance photonic FET memory. [ABSTRACT FROM AUTHOR]

With the growing demands of light fidelity technology, photonic transistor memory has gained considerable attention for next‐generation optoelectronic devices. In this work, alkylated rylenediimides of 2,9‐diphenethylanthra[2,1,9‐def:6,5,10‐d"e"f]diisoquinoline‐1,3,8,10(2H,9H)‐tetraone (C8‐PDI) and 2,7‐dioctylbenzo[lmn][3,8]phenanthroline‐1,3,6,8(2H,7H)‐tetraone (C8‐NDI), and pyromellitic diimide of 2,6‐dioctylpyrrolo[3,4‐f]isoindole‐1,3,5,7(2H,6H)‐tetraone (C8‐PMDI) have been used as floating gate electrets in the photonic field‐effect transistor‐type memory. The structure‐optics‐performance relationship of these rod‐like molecules has been systematically studied, and the memory device exhibited a decent response to photowriting and electrical erasing processes, owing to the 3D ordered smectic layer structure and brickwork stacking. Therefore, an evenly distributed photogating moiety, efficient exciton dissociation associated with decent carrier tunneling and charge trapping can be obtained. Among them, the sought‐after C8‐NDI presents favorable energy level alignment, multiband photoresponding, and an optimal block ratio. The fabricated photonic memory with C8‐NDI electret presented a remarkable memory switchability with a memory ratio of 104 and a stable memory ratio of 105 over 10,000 s. To the best of knowledge, this is the first work to utilize rylenediimides based liquid crystals as an efficient charge blocking electret, and these findings open an avenue for designing rod‐like molecules with highly ordered liquid crystalline properties in the ultrafast photomemory devices. [ABSTRACT FROM AUTHOR]