Self-calibrated NICE-OHMS based on an asymmetric signal: theoretical analysis and experimental validation.

As an ultra-sensitive detection technique, the noise-immune cavity enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) technique has great potential for assessment of the concentration of trace gases. To determine gas concentrations at the ppt or lower level with high accuracy, it is desirable that the technique exhibits self-calibration (or calibration-free) capabilities. Although being sensitive, NICE-OHMS has so far not demonstrated any such ability. To remedy this, this paper provides a self-calibrated realization of NICE-OHMS that is based on a switching of the feedback target of the DeVoe-Brewer (DVB) locking procedure from the modulation frequency of the frequency modulation spectroscopy (FMS) to the cavity length, which creates an asymmetrical signal whose form and size can be used to unambiguously assess the gas concentration. A comprehensive theoretical model for self-calibrated NICE-OHMS is established by analyzing the shift of cavity modes caused by intracavity absorption, demonstrating that gas absorption information can be encoded in both the laser frequency and the NICE-OHMS signal. To experimentally verify the methodology, we measure a series of dispersion signals under different levels of absorbance using a built experimental setup. An instrument factor and the partial pressure are obtained by fitting the measured signal through theoretical expressions. Our results demonstrate that fitted values are more accurate for higher partial pressures than for lower. To improve on the accuracy at low partial pressures, it is shown that the instrument factor obtained by fitting the signal at large partial pressures (in this case, above 7.8 µTorr) can be set to a fixed value for all fits. By this, the partial pressures can be assessed with a relative error below 0.65%. This technique has the potential to enable calibration-free ultra-sensitive gas detection.

Flow performance of porous implants with different geometry: Line, surface, and volume structures.

Additive manufacturing has enormous advantage of personalized adaptation. Particularly, porous implants have been widely used in clinical practice. Porous implant has the advantages and abilities to promote tissue growth and mass transfer, which are closely related to pore morphology. The purpose of this study is to investigate the effects of three porous structures, i.e., line structure, surface structure, and volume structure, on the flow properties of implants at different porosity. Therefore, a unit cell was selected from each type of structure (oct truss [OT], gyroid [G], and schwarz p [P]) as a typical cell, where OT is a line structure, G is a surface structure, and P is a volume structure. The scaffolds with different porosity of these cells were customized, and the shape parameters were measured and calculated. Then, the flow performance of three different scaffolds in Dulbecco's modified Eagle's medium was simulated by using computational fluid dynamics, and the flow velocity, permeability, and wall shear stress, which can reflect their biological properties, were calculated and compared. The results showed that the pore shape and porosity of porous implants greatly affected the physical parameters and performance of structures. These findings will contribute to unit cell selection and future performance optimization of porous implants.

Cyber violence caused by the disclosure of route information during the COVID-19 pandemic.

Disclosure of patients' travel route information by government departments has been an effective and indispensable pandemic prevention and control measure during the COVID-19 pandemic. However, this measure may make patients susceptible to cyber violence (CV). We selected 13 real cases that occurred in China during the COVID-19 pandemic for analysis. We identified several characteristics that commonly appeared due to route information, such as rumors about and moral condemnation of patients, and determined that patients who are the first locally confirmed cases of a particular wave of the pandemic are more likely to be the victims of CV. We then analyzed and compared six real cases using data mining and network analysis approaches. We found that disclosing travel route information increases the risk of exposing patients to CV, especially those who violate infection prevention regulations. In terms of disseminating information, we found that mainstream media and influential we-media play an essential role. Based on the findings, we summarized the formation mechanism of route information disclosure-caused CV and proposed three practical suggestions-namely, promote the publicity of the media field with the help of mainstream media and influential we-media, optimize the route information collection and disclosure system, and ease public anxiety about the COVID-19 pandemic. To our knowledge, this study is one of the first to focus on CV on social media during the COVID-19 pandemic. We believe that our findings can help governments better carry out pandemic prevention and control measures on a global scale.

Fiber pigtailed DFB laser-based optical feedback cavity enhanced absorption spectroscopy with a fiber-coupled EOM for phase correction.

A novel technique for performing fiber pigtailed DFB laser and linear Fabry-Pérot cavity based optical feedback cavity enhanced absorption spectroscopy (OF-CEAS) is proposed. A fiber-coupled electro-optic modulator (f-EOM) with x-cut y-propagation LiNbO3 waveguide is employed, instead of PZT used in traditional OF-CEAS, to correct the feedback phase, which improves the compactness and applicability of OF-CEAS. Through the efficient and real-time control of the feedback phase by actively changing the input voltage of the f-EOM, a good long-term stability of the signal has been achieved. Consequently, a detection sensitivity down to 7.8×10-10 cm-1, better than the previous by PZT based OF-CEAS, has been achieved over the integration time of 200 s, even by use of a cavity with moderate finesse of 2850.

Scaling laws of electroconvective flow with finite vortex height near permselective membranes.

In a steady state, the linear scaling laws are confirmed between the intensity characteristics of electroconvective (EC) vortex (including the vortex height and electroosmotic slip velocity) and the applied voltage for the nonshear EC flow with finite vortex height near permselective membranes. This finding in the nonshear EC flow is different from the shear EC flow [Kwak et al., Phys. Rev. Lett. 110, 114501 (2013)10.1103/PhysRevLett.110.114501] and indicates that the local concentration gradient has a significant improvement in the analysis of slip velocity. Further, our study reveals that the EC vortex is mainly driven by the second peak effect of the Coulomb thrust in the extended space-charge layer, and the linear scaling law exhibited by the Coulomb thrust is an essential reason for the linear scaling laws of vortex intensity. The scaling laws proposed in this paper are supported by our direct numerical simulation data and previous experimental observations [Rubinstein et al., Phys. Rev. Lett. 101, 236101 (2008)10.1103/PhysRevLett.101.236101].

Shear electroconvective instability in electrodialysis channel under extreme depletion and its scaling laws.

The electroconvective instability (ECI) in an electrodialysis channel under a strong electric field is studied here. The phenomenon of ECI with extreme depletion (ECI-HD) is reported; that is, the overlapping vortices cause the extreme depletion zone to propagate in the horizontal direction. Using scaling theory and direct numerical simulation, we indicate a series of features under the ECI-HD. The decrease in ion transport rate with voltage in ECI-HD is different from the enhancement in the ECI with moderate depletion (ECI-MD), which results in a unique peak in the voltage-current curve. More importantly, we reveal that the ECI is regulated by a scaling factor consisting of the electric field, hydrodynamic coupling coefficient, and Péclet number. For the ECI-HD, the scaling factor has an opposite effect on the vortex size and overlimiting current as that on the ECI-MD. The extreme depletion zone of the ECI-HD also has an uncommon diffusion self-similar dynamics. These unique scaling laws allow one to establish the quantitative bridge between the ion concentration, electric field, and vortex size by the overlimiting current.

A novel methodology to directly pre-determine the relative wavelength response of DFB laser in wavelength modulation spectroscopy.

A novel methodology to directly pre-determine the relative wavelength response (RWR) of a DFB laser, in terms of a combined current linearly scanned wavelength response and current modulated wavelength response (CMWR), in wavelength modulation spectroscopy (WMS) is presented. It is shown that the assessed RWR can be used to mimic the measured response with standard deviation of discriminations that are below 3.4 × 10-3cm-1 under a variety of conditions. It is also shown that its performance supersedes two commonly used assessment models of the CMWR but is slightly worse than that of the third model, however with the benefit of solely using a single fitting parameter (the concentration) instead of more. When the novel method is applied to the assessment of CO2 concentration in a Herriot-type multipass cell by using the technique of calibration-free WMS, the results show that there is virtually no difference compared to that by use of the best of the other methods. It is concluded that the novel method is more robust and simplifies the retrieval process of gas concentration.

Synthesis, Insecticidal, Fungicidal Activities and Structure⁻Activity Relationships of Tschimganin Analogs.

For the first time, a novel series of tschimganin analogs were designed, synthesized, and evaluated for their insecticidal and fungicidal activities. Their structures were characterized by ¹H-NMR, 13C-NMR and HRMS. Some of these compounds displayed excellent insecticidal and fungicidal activities, suggesting that they have potential to be used as bifunctional agrochemicals. Compound 3d and 3g with electron donating groups showed better inhibitory activity and growth inhibition activity towards Helicoverpa armigera (Hübner). The properties and positions of the substituents on the benzene ring have an important influence on the acaricidal activity of tschimganin analogs. Topomer comparative molecular field analysis (CoMFA) was employed to develop a three-dimensional quantitative structure-activity relationship model for the compounds against Tetranychus turkestani Ugarov et Nikolski. It was indicated that higher electronegativity was beneficial for acaricidal activity. Moreover, compound 3r having a 2-hydroxy-3,5- dinitrophenyl moiety displayed a fungicidal spectrum as broad as azoxystrobin against these phytopathogens.

Design, Synthesis, and Antifungal Activity of Novel Aryl-1,2,3-Triazole-ß-Carboline Hybrids.

The copper catalytic azide and terminal alkyne cycloaddition reaction, namely "click chemistry", gives a new and convenient way to create l,4-disubstitutd-l,2,3-triazoles. In this work, 2-pyrrolecarbaldiminato⁻Cu(II) complexes were established as efficient catalysts for the three-component 1,3-dipolar cycloaddition reaction of arylboronic acid and sodium azide (NaN3) with terminal alkynes in ethanol at room temperature to 50 °C, 1,4-disubstituted 1,2,3-triazoles were synthesized. Following the optimized protocol, two series of new aryl-1,2,3-triazole-ß-carboline hybrids have been designed and synthesized, and the chemical structures were characterized by ¹H NMR, 13C NMR, and high-resolution mass spectrometry (HRMS). All of the target compounds were evaluated in vitro for their antifungal activity against Rhizoctorzia solani, Fusarium oxysporum, Botrytis cinerea Pers., sunflower sclerotinia rot, and rape sclerotinia rot by mycelia growth inhibition assay at 50 µg/mL. The antifungal evaluation of the novel hybrids showed that, among the tested compounds, 5a, 5b, 5c, and 9b showed good antifungal activity against sunflower sclerotinia rot. Specifically, compound 9b also exhibited high broad-spectrum fungicidal against all the tested fungi with inhibition rates of 58.3%, 18.52%, 63.07%, 84.47%, and 81.23%. However, for F. oxysporum, all the target compounds showed no in vitro antifungal activities with an inhibition rate lower than 20%. These results provide an encouraging framework that could lead to the development of potent novel antifungal agents.

Recent Advances on Bioactive Constituents in Ferula.

Preclinical Research The genus Ferula (Umbelliferea) is widely distributed across Central Asia and the Mediterranean. Some plants of the genus Ferula have been used as sources of pharmaceuticals for centuries. Ferula is a rich source of biologically active compounds, including coumarin derivatives, sesquiterpene-substituted compounds, daucane esters, humulane, and germacrane compounds, aromatic lactones and disulfide compounds. Therefore, utilizing these bioactive constituents with antimicrobial and insecticidal effects not only can provide a new strategy for developing drug and green pesticide, but also protect endangered plant resources. In the present review, research advances on the bioactive constituents of the genus Ferula the plant sources. Drug Dev Res 78 : 321-331, 2017. © 2017 Wiley Periodicals, Inc.

[Expression of interleukin 2 and IL-2 receptor after implanted tissue engineered bones constructed with allogeneic marrow stromal stem cells and bio-derived materials in rhesus monkeys].

OBJECTIVE: To explore the feasibility of allogeneic marrow stromal stem cells (MSCs) as seed cells to construct tissue engineered bone by detecting the expressions of interleukin 2 (IL-2) and IL-2 receptor in rhesus monkeys after implanting these tissue engineered bones. METHODS: Engineered bones were constructed with osteoblasts which derived from allogeneic MSCs and bio-derived materials in vitro, and then were implanted to bridge 2.5 cm segmental bone defects of left radius in 15 rhesus monkeys as experimental group, bio-derived materials only were implanted to bridge same size defects of right radius as control group. Every 3 monkeys were sacrificed in the 1st, the 2nd, the 3rd, the 6th and the 12th weeks postoperatively and the expressions of IL-2 and IL-2 receptor in blood and graft samples were detected quantitatively by enzyme-linked immunosorbent assay (ELISA). RESULTS: There was no significant difference in the contents of IL-2 and its receptor between 2 groups (P>0.05). The contents of IL-2 and its receptor increased from the 2nd week and maintained high level from the 2nd to the 6th week, but decreased after 6 weeks. CONCLUSION: Tissue engineered bones constructed with allogeneic MSCs and bio-derived materials show low immunogenicity. Allogeneic MSCs may be used as seed cells to construct tissue engineered bone.