Determination of Iron in Layered Crystal Sodium Disilicate and Sodium Silicate by Flame Atomic Absorption Spectrometry with Boric Acid as a Matrix Modifier

The effects of matrix silicate and experimental conditions on the determination of iron in flame atomic absorption spectrometry （FAAS） were investigated. It was found that boric acid as a matrix modifier obviously eliminated silicate interference. Under the optimum operating conditions, the determination results of iron in layered crystal sodium disilicate and sodium silicate samples by FAAS were satisfactory. The linear range of calibration curve is 0-10.5 μg.mL^-1, the relative standard deviation of method is 1.2%-2.2%, the recovery of added iron is 96.0%- 101%, the sensitivity is 0.19 μg.mL^-l and the detection limit is 77 ng.mL^-1. The effect of the determination of iron of the standard curve method, standard addition calibration and colorimetry method was the same, but the first has the merits of rapid sample preparation, reduced contamination risks and fast analysis.

Determining the imaging plane of a retinal capillary layer in adaptive optical imaging

Even in the early stage,endocrine metabolism disease may lead to micro aneurysms in retinal capillaries whose diameters are less than 10 μm.However,the fundus cameras used in clinic diagnosis can only obtain images of vessels larger than 20 μm in diameter.The human retina is a thin and multiple layer tissue,and the layer of capillaries less than10 μm in diameter only exists in the inner nuclear layer.The layer thickness of capillaries less than 10 μm in diameter is about 40 μm and the distance range to rod＆cone cell surface is tens of micrometers,which varies from person to person.Therefore,determining reasonable capillary layer（CL） position in different human eyes is very difficult.In this paper,we propose a method to determine the position of retinal CL based on the rod＆cone cell layer.The public positions of CL are recognized with 15 subjects from 40 to 59 years old,and the imaging planes of CL are calculated by the effective focal length of the human eye.High resolution retinal capillary imaging results obtained from 17 subjects with a liquid crystal adaptive optics system（LCAOS） validate our method.All of the subjects＇ CLs have public positions from 127 μm to 147 μm from the rod＆cone cell layer,which is influenced by the depth of focus.

A Study of Metal Ions Packing Hydrated Layer of Inclusion Crystals

The inclusion crystal formed by the hexamethylenamine with p-nitrophenol has a layer type structure,and is divided or- ganic layer and inorganic layer,the latter has a width of 1.0136nm.Metal ions can enter hydrated layer of the crystal,the con- tents of the cations and water in the crystal are determined.The XRD analysis of the layer type structure of the crystal is also giv- en.

Express Methods for Measurement of Electroconductivity of Semiconductor Layered Crystal

We describe theoretically the grounded method of measuring the conductivity of anisotropic layered semiconductor materials. The suggested method implies the use of a four-probe testing device with a linear arrangement of probes. The final expressions for identifying the electrical conductivity are presented in the form of a series of analytic functions. The suggested method is experimentally verified, and practical recommendations of how to apply it are also provided.

MULTIPLE CENTER d-β ORBITALS AND CHARGE TRANSFER OF HETERONUCLEAR COUSTERS WITH CUBANE TYPE (Mo_3S_4)_xM^n+ (x=1, 2, M = Cu, W, Ni, Sb. Mo, Sn, Cu_2; n = 4,8)

In this work, with the analysis on MO and electronic structure for a series of heteronuclear cluster with cubane type (Mo4S1 )xMn1(x=1.2. M = Cu, W, Ni, Sb, Mo, Sn, Cu2) we found that it is with the multiple center d-pir orbitals that the ligand Mo3S44+ bonds to the M atom to form these class clusters. It is revealed that the charges transfer from the M atom to Mo atom of the ligand Mo3S44+ and its relationship with the MC (multiple center) d-pπ orbitals. Based on the charge transfer the electronic spectrum and the magnetic property of some cubane clusters have been discussed.

Fullerene solar cells with cholesteric liquid crystal doping

This paper reports the doping effect of cholesteric liquid crystal 3β-Hydroxy-5-cholestene 3-oleate on polymer solar cells composed of the poly 3-hexyl thiophene and the fullerene derivative.With a doping ratio of 0.3 wt%,the device achieves an ideal improvement on the shunt resistor and the fill factor.Compared with the reference cell,the power conversion efficiency of the doped cell is improved 24%.The photoelectric measurement and the active layer characterization indicate that the self-assembly liquid crystal can improve the film crystallization and reduce the membrane defect.

Tunable terahertz filter based on alternative liquid crystal layers and metallic slats

We propose and demonstrate a pseudo Fabry–Pérot filter in the terahertz frequency range of 0.1–0.5 THz. It consists of alternative liquid crystal layers and metallic slats. Separate sharp resonant peaks are shown in the simulated transmission spectra, and their positions shift toward higher frequencies when the refractive index of liquid crystal decreases. The measured transmission spectra are consistent with corresponding simulations. Via thermally tuning the refractive index of the filled liquid crystal, the resonant transmission frequencies shift accordingly. The work supplies a novel design for tunable terahertz filters, which would play important roles in terahertz imaging, sensing, high speed communication, and security applications.

Electron transport layer driven to improve the open-circuit voltage of CH_3NH_3PbI_3 planar perovskite solar cells

Suitable electron transport layers are essential for high performance planar perovskite heterojunction solar cells. Here, we use ZnO electron transport layer sputtered under oxygen-rich atmosphere at room temperature to decrease the hydroxide and then suppress decomposition of perovskite films. The perovskite films with improved crystallinity and morphology are achieved. Besides, on the ZnO substrate fabricated at oxygen-rich atmosphere, open-circuit voltage of the CH_3NH_3PbI_3-based perovskite solar cells increased by 0.13 V.A high open-circuit voltage of 1.16 V provides a good prospect for the perovskite-based tandem solar cells. The ZnO sputtered at room temperature can be easily fabricated industrially on a large scale, therefore, compatible to flexible and tandem devices. Those properties make the sputtered ZnO films promising as electron transport materials for perovskite solar cells.

Photophysical,optical,and photocatalytic hydrogen production properties of layered-type BaNb_(2-x)Ta_(x)P_(2)O_(11)(x=0,0.5,1.0,1.5,and 2.0)compounds

Layered-type metal phosphates of BaNb_(2-x)Ta_(x)P_(2)O_(11)(x=0,0.5,1.0,1.5,and 2.0)were synthesized using a solid-state reaction method.The photophysical,optical,and photocatalytic hydrogen production properties of the resulting powders were investigated for the first time.Phase-pure and homogeneous powders with irregular morphologies were obtained at a calcination temperature of 1200℃.As the Ta content increased,the interlayer distance along the c-axis increased by up to 0.14%.Additionally,the optical bandgap values increased from 3.32 to 3.59 eV.The energy band positions were estimated from the Mott–Schottky measurements.BaNb_(2)P_(2)O_(11)(x=0)exhibited the lowest conduction band edge position(-0.14 V vs.the normal hydrogen electrode,NHE),which is located above the water reduction potential(0.0 V vs.NHE).In comparison,BaTa_(2)P_(2)O_(11)(x=2.0)exhibited the highest conduction band edge position(-0.29 V vs.NHE),comparable to that of TiO_(2).The photocatalytic activity for hydrogen produced from splitting water was measured under ultraviolet light irradiation.Notably,BaTa_(2)P_(2)O_(11)exhibited the highest activity(7.3μmol/h),which was 15 and 10 times larger than BaNb_(2)P_(2)O_(11)(0.5μmol/h)and nano-TiO_(2)(0.7μmol/h),respectively.The activity of BaTa_(2)P_(2)O_(11)increased to 24.4μmol/h after deposition of the NiO_(x)co-catalyst(1 wt.%),which remained stable during continuous operation(~35 h).

Experimental evidence of Bloch surface waves on photonic crystals with thin-film LiNbO_3 as a top layer

Strong nonlinear, electro-optical, and thermo-optical properties of lithium niobate(LN) have gained much attention. However, the implementation of LiNbO_3 in real devices is not a trivial task due to difficulties in manufacturing and handling thin-film LN. In this study, we investigate an optical device where the Bloch surface wave(BSW) propagates on the thin-film LN to unlock its properties. First, access to the LN film from air(or open space) is important to exploit its properties. Second, for sustaining the BSW, one-dimensional photonic crystal(1DPhC) is necessary to be fabricated under the thin-film LN. We consider two material platforms to realize such a device: bulk LN and commercial thin-film LN. Clear reflectance dips observed in far-field measurements demonstrate the propagation of BSWs on top of the LN surface of the designed 1DPhCs.

High-performance piezoresistive sensors based on transfer-free large-area PdSe_(2) films for human motion and health care monitoring

Two-dimensional transition metal dichalcogenides(TMDs)are needed in highperformance piezoresistive sensors due to their strong strain-induced bandgap modification and thereby large gauge factors.However,integrating a conventional high-temperature chemical vapor deposition(CVD)-grown TMD with a flexible substrate necessitates a transfer process that inevitably degrades the sensing properties of the TMDs and increases the overall fabrication complexity.We present a high-performance piezoresistive strain sensor that employs largearea PdSe_(2) films grown directly on polyimide(PI)substrates via plasma-assisted selenization of a sputtered Pd film.The reliable strain transfer from the substrate to the PdSe_(2) film ensures an outstanding strain-sensing capability of the sensor.Specifically,the sensors have a gauge factor of up to315±2.1,a response time under 25 ms,a detection limit of 8×10^(-6),and an exceptional stability of over 104 loadingunloading cycles.By attaching the sensors to the skin surface,we demonstrate their application for measuring physiological parameters in health care monitoring,including motion,voice,and arterial pulse vibration.Furthermore,using the PdSe_(2) film sensor combined with deep learning technology,we achieved intelligent recognition of artery temperature from arterial pulse signals with only a 2%difference between predicted and actual temperatures.The excellent sensing performance,together with the advantages of low-temperature fabrication and simple device structure,make the PdSe_(2) film sensor promising for wearable electronics and health care sensing systems.

Investigation of black phosphorus as a nano-optical polarization element by polarized Raman spectroscopy

Manipulating the polarization of light at the nanoscale is essential for the development of nano-optical devices. Owing to its corrugated honeycomb structure, two-dimensional （2D） layered black phosphorus （BP） exhibits outstanding in-plane optical anisotropy with distinct linear dichroism and optical birefringence in the visible region, which are superior characteristics for ultrathin polarizing optics. Herein, taking advantage of polarized Raman spectroscopy, we demonstrate that layered BP with a nanometer thickness can remarkably alter the polarization state of a linearly-polarized laser and behave as an ultrathin optical polarization element in a BP-Bi2Se3 stacking structure by inducing the exceptionally polarized Raman scattering of isotropic Bi2Se3. Our findings provide a promising alternative for designing novel polarization optics based on 2D anisotropic materials, which can be easily integrated in micro- sized all-optical and optoelectronic devices.