Thin-film lithium niobate electro-optic isolator fabricated by photolithography assisted chemo-mechanical etching.

We report an electro-optic isolator fabricated on thin-film lithium niobate by photolithography-assisted chemo-mechanical etching that shows an isolation of 39.50 dB and an overall fiber-to-fiber loss of 2.6 dB.

Density and row spacing of short-season cotton suitable for machine picking in the cotton region of Yellow River Basin.

To determine the suitable planting density and row spacing of short-season cotton suitable for machine picking in the Yellow River Basin of China, we conducted a two-year field experiment in Dezhou during 2018-2019. The experiment followed a split-plot design, with planting density (82500 plants·hm-2 and 112500 plants·hm-2) as the main plots and row spacing (equal row spacing of 76 cm, wide-narrow row spacing of 66 cm+10 cm, equal row spacing of 60 cm) as the subplots. We examined the effects of planting density and row spacing on growth and development, canopy structure, seed cotton yield and fiber quality of short-season cotton. The results showed that plant height and LAI under high density treatment were significantly greater than those under low density treatment. The transmittance of the bottom layer was significantly lower than under low density treatment. Plant height under 76 cm equal row spacing was significantly higher than that under 60 cm equal row spacing, while that under wide-narrow row spacing (66 cm +10 cm) was significantly smaller than that under 60 cm equal row spacing in peak bolling stage. The effects of row spacing on LAI varied between the two years, densities, and growth stages. On the whole, the LAI under the wide-narrow row spacing (66 cm+10 cm) was higher, with the curve declining gently after the peak, and it was higher than that in the two cases of equal row spacing in the harvest time. The change in transmittance of the bottom layer presented the opposite trend. Density, row spacing, and their interaction had significant effects on seed cotton yield and its components. In both years, seed cotton yield was the highest (3832 kg·hm-2 in 2018, 3235 kg·hm-2 in 2019) under wide-narrow row spacing (66 cm+10 cm), and it was more stable at high densities. Fiber quality was less affected by density and row spacing. To sum up, the optimal density and row spacing of short-season cotton were as follows: density with 112500 plants·hm-2 and wide-narrow row spacing (66 cm+10 cm).

High-Production-Rate Fabrication of Low-Loss Lithium Niobate Electro-Optic Modulators Using Photolithography Assisted Chemo-Mechanical Etching (PLACE).

Integrated thin-film lithium niobate (LN) electro-optic (EO) modulators of broad bandwidth, low insertion loss, low cost and high production rate are essential elements in contemporary interconnection industries and disruptive applications. Here, we demonstrated the design and fabrication of a high performance thin-film LN EO modulator using photolithography assisted chemo-mechanical etching (PLACE) technology. Our device shows a 3-dB bandwidth over 50 GHz, along with a comparable low half wave voltage-length product of 2.16 Vcm and a fiber-to-fiber insertion loss of 2.6 dB. The PLACE technology supports large footprint, high fabrication uniformity, competitive production rate and extreme low device optical loss simultaneously, our result shows promising potential for developing high-performance large-scale low-loss photonic integrated devices.

Electromagnetic Exposure Dosimetry Study on Two Free Rats at 1.8 GHz via Numerical Simulation.

Normally, the impact of electromagnetic exposure on human health is evaluated by animal study. The biological effect caused by electromagnetic exposure on such experimental animals as rats has been proven to be dose-dependent. However, though the dose of radio frequency (RF) electromagnetic exposure described by the specific absorbing rate (SAR) on fixed rats has been relatively well-studied utilizing the numerical simulations, the dosimetry study of exposure on free rat is insufficient, especially in the cases of two or more free rats. Therefore, the present work focuses on the variation of SAR caused by the existence of neighboring free rat in the same cage. Here, infrared thermography was used to record the activity of the two free rats who lived in the same cage that mounted at the far-field region in the microwave darkroom for a duration of 48 h. Then, using image processing techniques, the relative positions and orientations of the two rats are identified, which are defined by three parameters, such as the relative distance (d), relative direction angle (α), and relative orientation angle (ß). Using the simulation software XFdtd 7.3, the influence of d, α, and ß on the whole-body average SAR (WB-avgSAR) of the rats exposed to 1.8 GHz electromagnetic wave was calculated and analyzed. Then, the average variation of WB-avgSAR of the two rats compared with that of a single rat within 48 h was calculated. The numerical simulation results showed that the relative posture position described by (d, α, and ß) of the two rats affects their WB-avgSAR and leads to fluctuations at different positions. However, the variation rate of the 48-h-average WB-avgSAR was only 10.3%, which implied that the over-time average SAR of two or more rats can be roughly described by the WB-avgSAR of a single free rat, except when a real-time precise control of exposure dose is necessary.

A novel manganese chelated macromolecular MRI contrast agent based on O-carboxymethyl chitosan derivatives.

Currently used Gd-based and Mn-based small molecular MRI contrast agents fail to meet the requirements for the long-term monitoring, and the potential safety risk under high administration dose or repeat dosing needs to be considered. In the present study, a biocompatible macromolecular magnetic resonance imaging (MRI) contrast agents based on O-carboxymethyl chitosan (CMCS), CMCS-(Mn-DTPA)n was designed and synthesized. The relaxivity of CMCS-(Mn-DTPA)n is approximately 3.5 and 5.5 times higher than that of Gd-DTPA and Mn-DPDP in aqueous solution, respectively. The MRI signal intensity in the kidney and liver of Sprague Dawley (SD) rats is significantly increased at a dose of 0.03 mM Mn/kg b.w. CMCS-(Mn-DTPA)n accompanied by a long effective imaging window. According to in vitro studies, CMCS-(Mn-DTPA)n exhibits good cellular and blood biocompatibility at the dose necessary for MRI imaging. Based on the results from in vivo studies, manganese (Mn) is completely excreted from SD rats within ten days after administration and does not exert a pathological effect on the liver. CMCS-(Mn-DTPA)n represents a potentially novel MRI contrast agent due to its excellent relaxivity, long effective imaging window and good biocompatibility.

Multivariable quantitative relation between cell viability and the exposure parameters of 9.33 GHz RF-EMP irradiation.

Qualitative analysis of the influence of a certain exposure parameter is commonly performed in bioelectromagnetic studies. However, since the exposure condition requires the control of multiple parameters, the diverse results caused by different combinations of these parameters requires further quantitative study of the multivariable (exposure parameters)-bioeffect relation to identify the rule describing bioelectromagnetic effects. The present work investigated the relation between cell viability and the three main exposure parameters (electric intensity (Es), pulse duration (τ) and pulse number (N)) of 9.33 GHz radiofrequency electromagnetic field (RF-EMP). Experiments showed that the inhibitory rate of cell viability (ρ) had a proportional relationship with Es and exponential relationship with N; the equation [Formula: see text] is proposed to quantitatively describe the relation between the cell viability and these three exposure parameters. This equation can be used to predict the significance of a 9.33 GHz RF-EMP-induced bioeffect under the conditions Es <106 kV/m, N < 100, and 300 < τ < 750 ns, under which nonthermal bioeffects dominate for 9.33GHz RF-EMP exposure.

The specific absorption rate of tissues in rats exposed to electromagnetic plane waves in the frequency range of 0.05-5 GHz and SARwb in free-moving rats.

As electromagnetic exposure experiments can only be performed on small animals, usually rats, research on the characteristics of specific absorption rate (SAR) distribution in the rat has received increasing interest. A series of calculations, which simulated the SAR in a male rat anatomical model exposed to electromagnetic plane waves ranging from 0.05 to 5 GHz with different incidence and polarization, were conducted. The whole-body-averaged SAR (SARwb) and the tissue-averaged SAR (SARavg) in 20 major tissues were determined. Results revealed that incidence has great impact on SAR in the rat at higher frequencies owing to the skin effect and the effect on SARavg in tissues is much more apparent than that on SARwb; while polarization plays an important role under lower frequencies. Not only the incidence, but also the polarization in the rat keeps changing when the rat is in free movement. Thus, this article discussed a convenient way to obtain relatively accurate SARwb in a free-moving rat.

Cytotoxicity of AgNPs/CS composite films: AgNPs immobilized in chitosan matrix contributes a higher inhibition rate to cell proliferation.

In this study, the cytotoxicity of sliver nanoparticle-doped chitosan composite films (AgNPs/CS) was investigated in vitro. In this slow-release system, the doped silver nanoparticles (AgNPs) might modify both the surface properties of the matrix and the ion environment of the surrounding fluid via slow-release, determining the dominant mechanism is of interest. Here, AgNPs (average size is 25 nm) were doped into chitosan (CS) films by mechanical mixing to form a slow-release system. The surface properties and stabilities of the films and the Ag-releasing behavior were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible spectrophotometry, and a weight loss method. The morphology of adhered cells and the survival rate (obtained by both MTT and CCK-8 assays) of human umbilical vein endothelial cells (HUVEC) were employed to describe the cytotoxicity. Using statistical analysis, the following conclusions can be made: the doped AgNPs dispersed in the CS matrix with a polycrystalline structure. During the early erosion, a small amount of debris peeled off and became suspended in the fluid. After that erosion, the composite film became relatively stable, and the doped Ag was slowly released into the fluid. In comparison with the released Ag (either in the peeled debris or dissolved in the fluid), Ag immobilized in the AgNPs/CS films shows a more significant influence on cell adhesion and subsequent proliferation. Film thickness and AgNP content show a synergistic effect on the survival rate of the cell, with the AgNPs content being the key factor.