Diurnal Variation of Tropical Ice Cloud Microphysics: Evidence from Global Precipitation Measurement Microwave Imager (GPM-GMI) Polarimetric Measurements.

The diurnal variation of tropical ice clouds has been well observed and examined in terms of the occurring frequency and total mass but rarely from the viewpoint of ice microphysical parameters. It accounts for a large portion of uncertainties in evaluating ice clouds' role on global radiation and hydrological budgets. Owing to the advantage of precession orbit design and paired polarized observations at a high-frequency microwave band that is particularly sensitive to ice particle microphysical properties, three years of polarimetric difference (PD) measurements using the 166 GHz channel of Global Precipitation Measurement Microwave Imager (GPM-GMI) are compiled to reveal a strong diurnal cycle over tropical land (30°S-30°N) with peak amplitude varying up to 38%. Since the PD signal is dominantly determined by ice crystal size, shape, and orientation, the diurnal cycle observed by GMI can be used to infer changes in ice crystal properties. Moreover, PD change is found to lead the diurnal changes of ice cloud occurring frequency and total ice mass by about 2 hours, which strongly implies that understanding ice microphysics is critical to predict, infer, and model ice cloud evolution and precipitation processes.

Structural dependence of silver nanowires on polyvinyl pyrrolidone (PVP) chain length.

The effect of the chain length of polyvinyl pyrrolidone (PVP) on the structures of silver nanowires (AgNWs) is explored in this study. It was found in the experiments that PVP, when serving as a capping agent, has a great impact on the morphology and structure of AgNWs. By means of a series of experiments and the inquiry of the growth mechanism, the critical minimum PVP chain length for the successful formation of uniform nanowires was discovered, below which only nanoparticles or short nanorods can be obtained. Surprisingly, a core-shell structure of a nanowire with a polycrystal was observed when PVP with a very long chain length was employed in the processing.

One-step achieving high performance all-solid-state and all-in-one flexible electrochromic supercapacitor by polymer dispersed electrochromic device strategy.

Electrochromic devices (ECD) are widely used to regulate the transmittance of sunlight by applying a small voltage, but the drawbacks like complex layer-by-layer preparation procedures and inconvenient assembling process still exist. To address these problems, gel or solution-type all-in-one ECDs were recently developed for the simple structure, however, the leakage risk and absence of flexible large-area production have limited real applications. Herein, a novel all-solid-state and all-in-one flexible ECD was reported by originally developed polymer dispersed electrochromic device (PDECD) strategy. This all-solid-state flexible ECD could be efficiently prepared only by one step of phase separation without any extra treatment, and demonstrated outstanding stability (92.1 % of original ΔT remained after 10,000 cycles), high coloration efficiency (197 cm2/C), low power consumption (86.4 µW/cm2) and satisfied response time (≤12 s). Meanwhile, the stored power in ECD during coloring process could drive a LED with excellent cyclic stability (93 % of original capacity remained after 3000 cycles), implying that ECD could also serve as an idea electrochromic supercapacitor. What'more, a reported largest viologen-based all-solid-state flexible ECD (17.8 × 13.2 cm2) with robust bending resistance (up to 1000 bending cycles) was successfully fabricated with industrial roller coating technique, which indicated the huge potential in real world.

Deep Learning Enabled SERS Identification of Gaseous Molecules on Flexible Plasmonic MOF Nanowire Films.

Through the capture of a target molecule at the metal surface with a highly confined electromagnetic field induced by surface plasmon, surface enhanced Raman spectroscopy (SERS) emerges as a spectral analysis technology with high sensitivity. However, accurate SERS identification of a gaseous molecule with low density and high velocity is still a challenge due to its difficulty in capture. In this work, a flexible paper-based plasmonic metal-organic framework (MOF) film consisting of Ag nanowires@ZIF-8 (AgNWs@ZIF-8) is fabricated for SERS detection of gaseous molecules. Benefiting from its micronanopores generated by the nanowire network and ZIF-8 shell, the effective capture of the gaseous molecule is achieved, and its SERS spectrum is obtained in this paper-based flexible plasmonic MOF nanowire film. With optimal structure parameters, spectra of gaseous 4-aminothiophenol, 4-mercaptophenol, and dithiohydroquinone demonstrate that this film has good SERS performance, which could maintain obvious Raman signals within 30 days during reproducible detection. To realize SERS identification of gaseous molecules, deep learning is performed based on the SERS spectra of the mixed gaseous analyte obtained in this flexible porous film. The results point out that an artificial neural network algorithm could identify gaseous aldehydes (gaseous biomarker of colorectal cancer) in simulated exhaled breath with high accuracy at 93.7%. The integration of the flexible paper-based film sensors with deep learning offers a promising new approach for noninvasive colorectal cancer screening. Our work explores SERS applications in gaseous analyte detection and has broad potential in clinical medicine, food safety, environmental monitoring, etc.

Synthesis of Silver Nanowires Using a Polyvinylpyrrolidone-Free Method with an Alpinia zerumbet Leaf Based on the Oriented Attachment Mechanism.

In this study, silver nanowires (AgNWs) were successfully synthesized by using a polyvinylpyrrolidone (PVP)-free hydrothermal method with an Alpinia zerumbet leaf chunk as a reducing agent and template. Meanwhile, the mechanism of biomass synthesis of AgNWs is also explored. The AgNWs have a diameter of ∼77 nm and a length of ∼10 µm. During the hydrothermal process, the biomass initially serves as a reducing agent to reduce silver ions. As the reaction proceeds, the biomass will form a pipe-shaped soft template by hydrothermal carbonization. Silver ions are adsorbed and reduced along the pipe-shaped soft templates to form silver nanorods, and adjacent nanorods are merged to AgNWs. Thus, AgNWs are grown along the pipeline soft template based on the oriented attachment mechanism. Inspired by this, the mechanism of the polyol method was further investigated. In the initial growth stage, AgNWs synthesized by the polyol method have a V-shaped notch. Therefore, AgNWs synthesized by the polyol method may also grow on the basis of the oriented attachment mechanism with PVP as a template.

One-Pot Biosynthesis of Carbon-Coated Silver Nanoparticles Using Palm Leaves as a Reductant and a Carbon Source.

In this study, carbon-coated silver nanoparticles (Ag@C NPs) were synthesized with a one-pot hydrothermal method using palm leaves as a reductant and a carbon source. SEM, TEM, XRD, Raman, and UV-vis analyses were employed to characterize the as-prepared Ag@C NPs. Results showed that the diameter of silver nanoparticles (Ag NPs) and the coating thickness could be controlled by changing the amount of biomass and the reaction temperature. The diameter ranged from 68.33 to 143.15 nm, while the coating thickness ranged from 1.74 to 4.70 nm. As the biomass amount and the reaction temperature increased, the diameter of Ag NPs and the coating thickness became larger. Thus, this work provided a green, simple, and feasible method for the preparation of metal nanocrystals.

Investigating the adhesion of water droplets at low temperatures.

Adhesion of droplets to solid surfaces at low temperatures is crucial for antifogging and antifreezing, etc. So far, most reports on adhesion measurements have been carried out in air-liquid-solid systems, but it remains difficult to precisely investigate the adhesion at low temperatures due to the uncontrollable condensation. On the basis of the liquid-liquid-solid system, a new method to measure the adhesion of water droplets at low temperatures was developed and employed. Moreover, the reported method could be viable in other liquid-liquid-solid systems with wider temperature window; thus, it will find applications in broad fields such as crude oil recovery, ore-dressing, and transfer printing.

Modeling the Radiative Effect on Microphysics in Cirrus Clouds Against Satellite Observations.

The radiative effect on microphysics (REM) plays an important role in the dew/frost formation near the surface. How REM impacts cirrus clouds is investigated in this study, using bin microphysical model simulations and coincident data of the CloudSat and Global Precipitation Measurement (GPM) satellites. REM affects ice crystal spectrum with two types: radiative cooling and warming. Radiative cooling, as predicted by the bin-model simulations, favors the formation of horizontally oriented ice crystals (HOICs), but radiative warming does not. Hence, a test of REM can be transformed to a test of HOICs, because HOICs can be measured by the microwave polarization observations of the GPM Microwave Imager (GMI) at 166 GHz. To analyze the GMI data for their HOIC distribution, clouds are sorted into four groups with different optical depth and altitude, based on the radiative cooling/warming ratio (or eta) computed with satellite-retrieved ice water content. Their HOIC distributions (e.g., the midlevel thick clouds have more HOICs than the high-level ones) agree well with those predicted by the bin-model simulations. The general agreement between the GMI observations and bin-model simulations suggests that REM is common in cirrus clouds and impacts cirrus clouds significantly.

Unprecedented Electrochromic Stability of a-WO3-x Thin Films Achieved by Using a Hybrid-Cationic Electrolyte.

With large interstitial space volumes and fast ion diffusion pathways, amorphous metal oxides as cathodic intercalation materials for electrochromic devices have attracted attention. However, these incompact thin films normally suffer from two inevitable imperfections: self-deintercalation of guest ions and poor stability of the structure, which constitute a big obstacle toward the development of high-stable commercial applications. Here, we present a low-cost, eco-friendly hybrid cation 1,2-PG-AlCl3·6H2O electrolyte, in which the sputter-deposited a-WO3-x thin film can exhibit both the long-desired excellent open-circuit memory (>100 h, with zero optical loss) and super-long cycling lifetime (∼20,000 cycles, with 80% optical modulation), benefiting from the formation of unique Al-hydroxide-based solid electrolyte interphase during electrochromic operations. In addition, the optical absorption behaviors in a-WO3-x caused by host-guest interactions were elaborated. We demonstrated that the intervalence transfers are primarily via the "corner-sharing" related path (W5+ ↔ W6+) but not the "edge-sharing" related paths (W4+ ↔ W6+ and/or W4+ ↔ W5+), and the small polaron/electron transfers taking place at the W-O bond-breaking positions are not allowed. Our findings might provide in-depth insights into the nature of electrochromism and provide a significant step in the realization of more stable, more excellent electrochromic applications based on amorphous metal oxides.

Radiatively Induced Precipitation Formation in Diamond Dust.

Radiative cooling leads to the formation of dew and frost. This process is extended into a numerical model to simulate the ice crystal characteristics of diamond dust. The model replicates the low ice crystal concentration of diamond dust and the precipitation in stationary air. Its results are consistent with the arctic observations that large ice crystals grow while small ones sublimate and partly explain the geographic and seasonal distributions of diamond dust such as the high frequency of diamond dust in the arctic regions and winter. Furthermore, its results show that plate/column-like ice crystals with radiative cooling grow in expense of quasi-spherical ice particles, partly explaining the ice crystal shapes observed in diamond dust.

Three Dimensional and Homogenous Single Cell Cyclic Stretch within a Magnetic Micropillar Array (mMPA) for a Cell Proliferation Study.

The physical properties of the extracellular matrix (ECM) are a key aspect of the cell microenvironment. A biological system is a highly dynamic organization. In our study, we designed and prepared a large area of magnetic PDMS elastomer micropillar array (mMPA) with robust and tunable movement for cell mechanics study. The rotational movement frequency of the micropillars could be precisely controlled by a home-built magnetic actuation apparatus. Cells cultured in the mMPA could be suspended in between two micropillars in a single level and exhibited a 3D structure. With the rotational movement of the micropillar, a homogeneous stretchable force could be applied to a single cell along it long axis with various frequencies. We exclusively studied the influence of dynamic properties of the micropillar movement on cell behaviors. We found that, by fixing the amplitude of the stretchable force, the frequency-based properties of the cell microenvironment could significantly change cell functions. The cell behaviors are dependent on the micropillar movement frequency and a transition from proliferation to apoptosis/death exhibited with the increment of the force application frequency.

Surface evolution of manganese chloride aqueous droplets resulting in self-suppressed evaporation.

The exchange kinetics of liquid water, which are of fundamental interest and have potential applications, remain unclear. A fantastic and extraordinary phenomenon was observed during the evaporation of a water droplet doped with manganese chloride. As observed from the evolution of this type of droplet, a thin film was formed on the surface with an exothermic phase transition, resulting in self-suppressed evaporation. The MnCl2-doped water droplets were maintained in a relative humidity (RH) of 50% at 40 °C for more than a week and for longer than two months at a temperature of 25 °C. In contrast, a pure water droplet can only be sustained for a few minutes. The self-suppressed evaporation of doped water may be due to the special hydration of the accumulated manganese and chloride ions at the surface, decreasing the surface tension.

Controlled H2O2 release via long-lived electron-hole separation mediated to induce tumor cell apoptosis.

Flexible films of polytungstate (PT) as active ingredients were fabricated in PDMS as a "band-Aid" to achieve controllable H2O2 release. In these different systems of an amorphous PT building block, the lengthened lifetime (bleaching process) of photo-electron-hole separation is attributed to the electron trapping of the PT network and the existence of hole scavengers. The hole scavengers further prevent recombination of electrons and holes, so that the long-lived photoelectron could provide sustainable reactive oxygen species (ROS) by trapped electrons. Transient absorption illustrates the kinetic competition between the process of photohole induced bleaching and coloration induced by weak irradiation, which suggests that the hole scavenger is vital for ROS generation. The signals of electron spin resonance further confirm the existence of ROS. The profiles of controllable H2O2 with various release efficiency were obtained via fluorescence studies. The results indicate that the H2O2 release efficiency is related to both the hole scavenger and the tungstate cluster. The released H2O2 on the responses of tumor cells were evaluated. Compared with a cancer drug, the controllable and reversible released H2O2 delivery is highly efficient in preventing the proliferation and inducing apoptosis of A375 melanoma cells.