Search

Abstract Background Boron (B) is an essential micronutrient for plants. Inappropriate B supply detrimentally affects the productivity of numerous crops. Understanding of the molecular responses of plants to different B supply levels would be of significance in crop improvement and cultivation practices to deal with the problem. Results We conducted a comprehensive analysis of the transcriptome and proteome of tobacco seedlings to investigate the expression changes of genes/proteins in response to different B supply levels, with a particular focus on B deficiency. The global gene and protein expression profiles revealed the potential mechanisms involved in the responses of tobacco to B deficiency, including up-regulation of the NIP5;1-BORs module, complex regulation of genes/proteins related to cell wall metabolism, and up-regulation of the antioxidant machinery. Conclusion Our results demonstrated that B deficiency caused severe morphological and physiological disorders in tobacco seedlings, and revealed dynamic expression changes of tobacco genes/proteins in response to different B supply levels, especially to B deficiency, thus offering valuable insights into the molecular responses of tobacco to B deficiency.

Ultrasonic-guided waves (UGWs) in defective pipes are subject to severe coherent noise caused by imperfect detection conditions, mode conversion, and intrinsic characteristics (dispersion and multiple modes), inducing the limited performance of anomaly imaging. To achieve the high resolution and accuracy of anomaly imaging, a multi-strategy hybrid sparse reconstruction (MHSR) method based on spatial–temporal sparse wavenumber analysis (ST-SWA) is proposed. MHSR leverages the capability of ST-SWA to extract the wavenumber dispersion curves, thereby providing a more refined and precise search space for MHSR. Furthermore, it mitigates the impact of coherent noise by conducting dispersion compensation on the reconstructed signal. The sparse compensated signals through MHSR are employed for sparse reconstruction imaging. To validate the efficacy of the proposed method, UGW testing is performed on the defective steel pipe, and the results demonstrate the significant enhancement of anomaly imaging in defect resolution and positioning accuracy. The lowest estimated errors for axial and circumferential defect positions are 10 mm and 4 mm, respectively.

High light (HL) significantly impacts plant photosynthesis. This study investigated the effects of different magnesium (Mg) levels (0, 1, 2, and 5 mol Mg plant−1; HMg0, HMg1, HMg2, and HMg5) on tobacco (Nicotiana tabacum L. cv. Cuibi No. 1) under HL (1500 μmol m−2 s−1), aiming to understand the role of Mg in mitigating the impact of HL on photosynthesis and carbon–nitrogen metabolism. Plants treated with 1 mol Mg plant−1 under 750 μmol m−2 s−1 light conditions served as the control. HL led to a reduced chlorophyll (Chl) content and inhibited the maximum photosynthetic rate (Pmax). It also decreased energy involved in photosynthetic electron transfer (ET) and electron flux to reduction end-electron acceptors at the photosystems I (PSI) acceptor side (RE) and caused photosynthetic system damage. H2O2 accumulation exacerbated membrane lipid peroxidation damage, disrupting carbon and nitrogen metabolism, and inducing antioxidant enzyme activity. HMg2 increased Chl content, stomatal conductance, intercellular CO2 concentration, and the net photosynthetic rate compared to HMg0. It enhanced ET efficiency, PSI and PSII functionality, reduced dissipated energy flux (DI), and minimized photosynthesis damage. Conversely, excessive Mg application (HMg5) decreased Pmax and PSII activity, increasing DI. Adequate Mg supply alleviated HL’s detrimental effects by enhancing Chl content and ET and RE efficiency.

Inflammatory responses and tumor developments are closely related, with interleukin-6 (IL-6) playing important roles in both processes. IL-6 has been extensively identified as a potential tumor biomarker. This study developed an isotope dilution mass spectrometry (IDMS) method for quantifying IL-6 based on signature peptides. These peptides were screened by excluding those with missed cleavage or post-translational modification. The method’s accuracy was verified using amino acid-based IDMS, in which purified IL-6 protein samples were quantified after hydrolyzing them into amino acids, and no significant difference was observed (p-value < 0.05). The method demonstrated good linearity and sensitivity upon testing. The specificity and matrix effect of the method were verified, and a precision study showed that the coefficient of variation was less than 5% for both the intra-day and inter-day tests. Compared to immunoassays, this method offers distinct advantages, such as the facilitation of multi-target analysis. Furthermore, the peptides used in this study are much more convenient for storage and operation than the antibodies or purified proteins typically used in immunoassays.

Chemodynamic therapy (CDT), a noninvasive strategy, has emerged as a promising alternative to conventional chemotherapy for treating tumors. However, its therapeutic effect is limited by the amount of H2O2, pH value, the hypoxic environment of tumors, and it has suboptimal tumor-targeting ability. In this study, tumor cell membrane-camouflaged mesoporous Fe3O4 nanoparticles loaded with perfluoropentane (PFP) and glucose oxidase (GOx) are used as a tumor microenvironment-adaptive nanoplatform (M-mFeP@O2-G), which synergistically enhances the antitumor effect of CDT. Mesoporous Fe3O4 nanoparticles are selected as inducers for photothermal and Fenton reactions and as nanocarriers. GOx depletes glucose within tumor cells for starving the cells, while producing H2O2 for subsequent ·OH generation. Moreover, PFP, which can carry O2, relieves hypoxia in tumor cells and provides O2 for the cascade reaction. Finally, the nanoparticles are camouflaged with osteosarcoma cell membranes, endowing the nanoparticles with homologous targeting and immune escape abilities. Both in vivo and in vitro evaluations reveal high synergistic therapeutic efficacy of M-mFeP@O2-G, with a desirable tumor-inhibition rate (90.50%), which indicates the great potential of this platform for clinical treating cancer.

This study aims to accurately determine the distribution of landslides in the complex terrain of Jiangdingya, Nanyu Township, Zhouqu County, Gansu Province. The digital orthophoto map (DOM) and digital elevation model (DEM) are used to accurately identify landslide areas and analyze associated data. Based on image-based supervised classification, the influence factor constraint analysis is used to further identify and delineate the landslide area. Three mathematical morphology operations—erosion, dilation, and opening—are then applied to automatically identify and extract landslides. Experimental results demonstrate that achieving an accuracy, precision, and recall of 98.02%, 85.24%, and 84.78% shows that it is possible to better avoid interference caused by complex terrain with rich features. High-resolution DEM and DOM data contain rich spectral and texture information. These data can accurately depict geomorphic features of complex terrain and aid in identifying landslide-prone areas when combined with mathematical morphology processing. This contribution is important for identifying landslides in complex terrain and emergency disaster management.

Studies have shed light on the impact of the co-application of inorganic fertilizer and biochar on soil fertility, health, and crop growth performance and yield. However, insufficient literature exists regarding the appropriate nitrogen reduction ratio for enhancing soil quality and maximizing crop nitrogen utilization following the application of biochar in a continuous tobacco-rice rotation field. Here, we explored nitrogen absorption and utilization patterns of tobacco crops, as well as the response characteristics of functional genes related to soil nitrogen cycling subjected to the interaction of reduced nitrogen utilization ratios following biochar application in a long-term tobacco-rice rotation field. The results showed that the treatments with 10% (T2) and 20% (T3) nitrogen reduction combined with biochar (30 t∙ha−1) promoted nitrogen utilization efficiency and nitrogen harvest index of tobacco plants. In the second year of the experiment, T2 and T3 significantly increased the nitrogen harvest index by 3.85% and 5.78% compared with the conventional nitrogen application treatment (T1), respectively. We believe that the increase in abundance of nitrification, nitrogen fixation, and ammonification genes, including nxrA, nifH, and UreC in the rhizosphere soil, precipitate the high nitrogen absorption and utilization efficiency in the biochar combined with nitrogen reduction treatments, respectively. This suggests that biochar application at a rate of 30 t·ha−1, nitrogen fertilizer usage can be reduced by 10% and 20% to achieve optimal and sustainable tobacco production.

Quantitatively describing the atomic configuration of the catalytically active sites is challenging. Here the authors demonstrate that tuning crystal-phase of metal single-particle enables to precisely describe the atomic structure of the active sites and accurately identify the activation routes of the reacting molecules.

The catalytic performance of metal‒organic frameworks can be tuned by introducing defects in their structure. Here, the authors introduce defects and impregnate ruthenium nanoparticles in cationic metal-organic frameworks, which enables enhanced recyclability and catalytic performance in D-glucose hydrogenation.

Ultrasonic guided waves (UGWs) in water-filled pipes are subject to more severe dispersion and attenuation than vacant pipes, posing significant challenges for defect identification and localization. To this end, a novel sparse signal decomposition method called orthogonal matching pursuit based on dispersion and multi-mode (DMOMP) was proposed, which utilizes the second-order asymptotic solution of dispersion curves and the conversion characteristics of asymmetric UGWs in the defect contact stage to reconstruct the dispersive signals and converts the time-domain dispersive signals to distance-domain non-dispersive signals by dispersion compensated time-distance mapping. The synthesized simulation results indicate that DMOMP not only exhibits higher reconstruction accuracy compared to OMP, but also reveals more accurate and stable mode recognition and localization compared to DOMP, which only considers the dispersion under perturbation and noise. In addition, the UGW testing experimental results of water-filled pipes verify the effectiveness of DMOMP, the localization accuracies of three feature signals (defct 1, defct 2 and end echo) with DMOMP are 99.10%, 98.72% and 98.36%, respectively, and the average localization accuracy of DMOMP is as high as 98.73%.

Cold stress is one of the major constraints limiting the productivity of many important crops, including tobacco (Nicotiana tabacum L.) production and quality worldwide. However, the role of magnesium (Mg) nutrition in plants has been frequently overlooked, especially under cold stress, and Mg deficiency adversely affects plant growth and development. Here, we evaluated the influence of Mg under cold stress on tobacco morphology, nutrient uptake, photosynthetic and quality attributes. The tobacco plants were grown under different levels of cold stress, i.e., 8°C, 12°C, 16°C, including with a controlled temperature of 25°C, and evaluated their effects with Mg (+Mg) and without Mg (–Mg) application. Cold stress resulted in reduced plant growth. However, the +Mg alleviated the cold stress and significantly increased the plant biomass on an average of 17.8% for shoot fresh weight, 20.9% for root fresh weight, 15.7% for shoot dry weight, and 15.5% for root dry weight. Similarly, the nutrients uptake also increased on average for shoot-N (28.7%), root-N (22.4%), shoot-P (46.9%), root-P (7.2%), shoot-K (5.4%), root-K (28.9%), shoot-Mg (191.4%), root-Mg (187.2%) under cold stress with +Mg compared to –Mg. Mg application significantly boosted the photosynthetic activity (Pn 24.6%) and increased the chlorophyll contents (Chl-a (18.8%), Chl-b (25%), carotenoids (22.2%)) in the leaves under cold stress in comparison with –Mg treatment. Meanwhile, Mg application also improved the quality of tobacco, including starch and sucrose contents, on an average of 18.3% and 20.8%, respectively, compared to –Mg. The principal component analysis revealed that tobacco performance was optimum under +Mg treatment at 16°C. This study confirms that Mg application alleviates cold stress and substantially improves tobacco morphological indices, nutrient absorption, photosynthetic traits, and quality attributes. In short, the current findings suggest that Mg application may alleviate cold stress and improve tobacco growth and quality.

Purpose: In the present study, to achieve high paclitaxel (PTX) loading in a conjugated drug delivery system with minimal long-term side effects, we formulated a novel degradable stereocomplexed micelle-like particle with a core-shell structure. Materials and methods: In this system, methoxy polyethylene glycol (MPEG) acted as the hydrophilic shell, and the stereocomplex of polylactic acid with PTX (SCPLA-PTX) acted as the hydrophobic core. The MPEG-SCPLA-PTX micelle-like particles were synthesized via the self-assembly of a MPEG-poly l-lactic acid (PLLA) copolymer with a PTX-poly d-lactic acid-PTX copolymer. The resultant copolymers and their intermediates were characterized using 1H nuclear magnetic resonance and GPC. Micelle-like particles with different molecular weight ratios of MPEG and PLLA were synthesized to demonstrate the functions of both components. Results: PTX loading into MPEG2000Da-PLLA6000Da particles reached as high as 20.11%. At 216 h, the cumulative release from MPEG5000Da-PLLA6000Da, MPEG2000Da-PLLA6000Da, and MPEG5000Da-PLLA22000Da particles were 51.5%, 37.7%, and 52.0%, respectively. Conclusions: According to the cell uptake experiments, inhibition of tumor cell growth was satisfactory, indicating that the stereocomplexed particles developed in the present study can be employed as a promising nanocarrier for PTX delivery.

Vanadium dioxide (VO2) thin films of different thicknesses were prepared by regulating the deposition time (2, 2.5, 3, and 3.5 h). The impact of deposition time on the microstructure, surface morphology, and cross-section morphology was investigated. The results showed that the grain size increased with the film thickness. Meanwhile, the influence of film thickness on the residual stress was evaluated by X-ray diffraction. The phenomenon of “compressive-to-tensile stress transition” was illustrated as the thickness increased. The change of dominant mechanism for residual stress was used for explaining this situation. First, the composition of residual stress indicates that growth stress play a key role. Then, the effect of “atomic shot peening” can be used to explain the compressive stress. Lastly, the increased grain size, lower grain boundary density, and “tight effect” in the progress of film growth cause tensile stress.

The present work reported the intrinsic mechanical behavior of vanadium dioxide (VO2) thin film deposited on a SiO2 substrate using a combination of nanoindentation tests and a theoretical model. The effect of phase transition on mechanical parameters was studied by adjusting the test temperature. A new model that can simultaneously extract the elastic modulus and hardness was derived by introducing a dimensional analysis. The results showed that the thin film exhibits a hardness of 9.43 GPa and a Young’s modulus of about 138.5 GPa at room temperature, compared with the values of 5.71 GPa and 126.9 GPa at a high temperature, respectively. It can be seen that the intrinsic mechanical parameters decrease to a certain extent after a phase transition. Finally, the numerical simulation results were consistent with those of the experiments, which verified the effectiveness of the new method. In addition, this study also provided useful guidance for mechanical tests on other ultra-thin films.

Pipeline systems are prone to defects due to the harsh service conditions, which may induce catastrophic failure if found not in time. Ultrasonic guided wave (UGW) testing provides a convenient option for pipeline detection, showing high-efficiency, non-contact, long-distance and large-scale capabilities. To address the problem that UGW signals suffer from poor signal resolution that is mainly related to the coherent noise caused by the dispersion, multi-mode and mode conversion, an advanced signal processing method called VWISSP, based on variational mode decomposition (VMD), wavelet transform (WT), and improved split spectrum processing (ISSP) was proposed, of which SSP was improved by replacing the Gaussian filter bank with cosine filters of constant frequency-to-bandwidth and frequency-to-filter spacing ratios. Compared with ISSP, VWISSP shows better higher accuracy and resolution processing effects to noisy multi-defect UGW signals, which is manifested through the improvement of both the signal-to-noise ratio gain and the defect-to-noise gain. Only feature signals (defects and pipe end) are retained, whereas noise signals are eliminated completely.

The buckling, de-lamination, and cracking of the thin film/substrate system caused by thermal stress is the main obstacle for functional failure. Moreover, the thermal stress of vanadium dioxide (VO2) thin film may be more complicated due to the stress re-distribution caused by phase transition. Therefore, the thermal stress of VO2 thin films deposited on four substrates with different materials (fused silica, silicon slice, sapphire, and glass) has been studied by finite element method in the present work. The influences of external temperature, substrate, and interlayer on thermal stress were analyzed. It was found that the substrates can greatly affect the thermal stresses, which were mainly caused by the mismatch of coefficient of thermal expansion (CTE). The thermal stress had a linear relationship with the external temperature, but this tendency would be redistributed or even change direction when phase transition occurred. The simulated results were in tandem with the analytical method. Meanwhile, the radial stress and shear stress distribution under the influence of phase transition were calculated. In addition, the reduction of thermal stress and shear stress showed that the appropriate interlayer can enhance the adhesive strength effectively.

Abstract Background This study was designed to test the hypothesis that κ-opioid receptor (κ-OR) stimulation reduces palmitate-induced HUVECs apoptosis and to investigate its mechanisms. Methods HUVECs were subjected to sodium palmitate, apoptosis and cell viability were determined, HUVECs were treated with specific inhibitors to PI3K, Akt, eNOS and siRNAs targeting κ-OR and Akt. Groups were divided as follows: the control group, the sodium palmitate group, the sodium palmitate+U50,488H (a selective κ-OR agonist) group and the sodium palmitate+U50,488H + nor-BNI (a selective κ-OR antagonist) group. Results Treatment with sodium palmitate significantly reduced cell viability and increased apoptosis rate which were significantly alleviated by pretreatment with U50,488H, the effect of U50,488H was abolished by nor-BNI. Phosphorylation of Akt and eNOS, as well as NO production were attenuated and accompanied by an increased expression of caspase 3 when HUVECs were subjected to sodium palmitate, and all these changes were restored by pretreatment with U50,488H, the effects of U50,488H were abolished by nor-BNI, and specific inhibitors to PI3K, Akt, eNOS, respectively. SiRNAs targeting κ-OR or Akt abolished the effects of U50,488H on phosphorylation of Akt and eNOS as well as the expressions of caspase 3, Bax and Bcl-2. SiRNAs targeting Akt elicited no effect on the expression of κ-OR. Conclusion This study provides the evidence for the first time that κ-OR stimulation possesses anti-palmitate-induced apoptosis effect, which is mediated by PI3K/Akt/eNOS signaling pathway.

Ultrasonic guided wave (UGW) nondestructive testing suffers from poor signal interpretation accuracy caused by the coherent noise that is related to dispersion, multi-mode and mode conversion. In order to split the L(0,2) UGW from the coherent noise, split-spectrum processing with raised cosine filters of constant frequency-to-bandwidth ratio (FBR-RC-SSP) is proposed. With the advantages of time domain resolution and frequency domain split, FBR-RC-SSP is studied based on time-frequency analysis using the chirplet transform, and the effects of filter parameters on signal-to-noise ratio gain (SNRG) and defect-to-coherent noise gain (DCRG) are explained. The excellent effects of eliminating the coherent noise and improving the signal resolution in FBR-RC-SSP are reported by the validation of synthesized, simulated and experimental UGW signals, of which the average SNRG and DCRG are 22.92% and 23.71% higher than those of traditional SSP using Gaussian filters, and it has the potential to locate and characterize defects in further UGW testing research.

κ-opioid receptor (κ-OR) plays a key role in preventing hypoxic pulmonary hypertension (HPH) development after activated by exogenous agonist U50,488H. Calcium sensing receptor (CaSR) activation induces HPH by promoting vasoconstriction and vascular remodeling. The activated κ-OR is reported to inhibit the expression of CaSR in pulmonary artery smooth muscle cells (PASMCs). Thus, in this study, we aimed to explore the effect of activated κ-OR on the role of CaSR in preventing HPH development. An HPH rat model was constructed using Sprague-Dawley rats. Changes in mean pulmonary arterial pressure (mPAP) and right ventricular pressure (RVP) mediated by κ-OR agonist U50,488H and CaSR inhibitor NPS2143 were observed. The effects of CaSR agonist spermine and inhibitor NPS2143 on pulmonary artery tension were tested. The expression and localization of κ-OR and CaSR were measured in isolated PASMCs. A cell-counting kit-8 assay was performed to evaluate the effect of spermine in PASMC proliferation. Expression of proliferating cell nuclear antigen (PCNA), Erk, and p-Erk was evaluated by western blot analysis. Results showed that κ-OR and CaSR were co-expressed and colocalized in PASMCs under normoxic and hypoxic conditions. Interactions between κ-OR and CaSR were also observed. Spermine improved vasoconstriction in the pulmonary artery in HPH rats, which was abolished by U50,488H. RVP and mPAP were significantly increased in HPH rats under CaSR stimulation, but were significantly reduced when the rats were pretreated with U50,488H and NPS2143 (P < 0.01). Spermine treatment significantly promoted PASMC proliferation, which was significantly inhibited by U50,488H, p38 inhibitor SB203580, JNK inhibitor SP600125, Erk inhibitor SCH772984, and MEK inhibitor U0126, especially Erk inhibitor (P < 0.01). Spermine significantly increased PCNA and P-Erk expression in hypoxic conditions, which was inhibited by U50,488H and NPS2143. κ-OR stimulation prevented HPH development via the CaSR/MAPK signaling pathway.

Background/Aims: In a previous study, we showed that κ-opioid receptor stimulation with the selective agonist U50,488H ameliorated hypoxic pulmonary hypertension (HPH). However, the roles that pulmonary arterial smooth muscle cell (PASMC) proliferation, apoptosis, and autophagy play in κ-opioid receptor-mediated protection against HPH are still unknown. The goal of the present study was to investigate the role of autophagy in U50,488H-induced HPH protection and the underlying mechanisms. Methods: Rats were exposed to 10% oxygen for three weeks to induce HPH. After hypoxia, the mean pulmonary arterial pressure (mPAP) and the right ventricular pressure (RVP) were measured. Cell viability was monitored using the Cell Counting Kit-8 (CCK-8) assay. Cell apoptosis was detected by flow cytometry and Western blot. Autophagy was assessed by means of the mRFP-GFP-LC3 adenovirus transfection assay and by Western blot. Results: Inhibition of autophagy by the administration of chloroquine prevented the development of HPH in the rat model, as evidenced by significantly reduced mPAP and RVP, as well as decreased autophagy. U50,488H mimicked the effects of chloroquine, and the effects of U50,488H were blocked by nor-BNI, a selective κ-opioid receptor antagonist. In vitro experiments showed that the inhibition of autophagy by chloroquine was associated with decreased proliferation and increased apoptosis of PASMCs. Under hypoxia, U50,488H also significantly inhibited autophagy, reduced proliferation and increased apoptosis of PASMCs. These effects of U50,488H were blocked by nor-BNI. Moreover, exposure to hypoxic conditions significantly increased AMPK phosphorylation and reduced mTOR phosphorylation, and these effects were abrogated by U50,488H. The effects of U50,488H on PASMC autophagy were inhibited by AICAR, a selective AMPK agonist, or by rapamycin, a selective mTOR inhibitor. Conclusion: Our data provide evidence for the first time that κ-opioid receptor stimulation protects against HPH by inhibiting PASMCs autophagy via the AMPK-mTOR pathway.

With the rapid development of modern manufacturing processes, ultra-precision structured freeform surfaces are being widely explored for components with special surface functioning. Measurement of the 3D surface form of structured specular objects remains a challenge because of the complexity of the surface form. Benefiting from a high dynamic range and large measuring area, phase measurement deflectometry (PMD) exhibits great potential in the inspection of the specular surfaces. However, the PMD is insensitive to object height, which leads to the PMD only being used for smooth specular surface measurement. Direct phase measurement deflectometry (DPMD) has been introduced to measure structured specular surfaces, but the surface form measurement resolution and accuracy are limited. This paper presents a method named stereo-DPMD for measuring structured specular objects by introducing a stereo deflectometor into DPMD, so that it combines the advantages of slope integration of the stereo deflectometry and discontinuous height measurement from DPMD. The measured object is separated into individual continuous regions, so the surface form of each region can be recovered precisely by slope integration. Then, the relative positions between different regions are evaluated by DPMD system to reconstruct the final 3D shape of the object. Experimental results show that the structured specular surfaces can be measured accurately by the proposed stereo-DPMD method.

Polymyxin E (PME) plays an important role in fighting against Gram-negative bacterial infections; however, it causes nephrotoxicity, which limits its clinical use. The aim of this study was to investigate the protective effects of a plant extract Panax notoginseng saponins (PNS) on PME-induced nephrotoxicity in mice. In vivo studies showed that PNS significantly reduced blood urea nitrogen (BUN), serum creatinine (CRE) and number of apoptotic cells in kidney, as well as renal histopathological damage which increased in the presence of PME, and suppressed PME-induced oxidative stress in kidney, as shown by the up-regulation of superoxide dismutase (SOD) and the down-regulation of malondialdehyde (MDA) levels. Furthermore, PNS inhibited the expression of Bax, while increased the expression of Bcl-2 compared to the PME-treated group. In vitro studies showed that PNS decreased intracellular reactive oxygen species (ROS) and MDA levels, increased glutathione (GSH) levels, and enhanced the activity of SOD and glutathione peroxidase (GSH-Px) in murine renal tubular epithelial cells (TCMK-1 cells). In addition, PNS enhanced cell viability and the expression of Bcl-2, restored the mitochondrial membrane potential, inhibited the expression of Bax, inhibited the activity of caspase-3 and caspase-9, and reduce apoptotic rate in PME-treated TCMK-1 cells. PNS could reduce PME-induced nephrotoxicity. The protective effects could result from inhibition of oxidative stress, and prevention of cell apoptosis via the mitochondrial pathway. These findings highlight the potential of PNS as a safe adjunct for ameliorating the nephrotoxicity.

The precise determination of the surface structure of iron oxides (hematite and magnetite) is a vital prerequisite to understand their unique chemical and physical properties under different conditions. Here, the atomic structure evolution of the hematite (0001) surface under reducing conditions was tracked by polarization-resolved infrared reflection absorption spectroscopy (IRRAS) using carbon monoxide (CO) as a probe molecule. The frequency and intensity of the CO stretch vibration is extremely sensitive to the valence state and electronic environments of surface iron cations. Our comprehensive IRRAS results provide direct evidence that the monocrystalline, stoichiometric α-Fe2O3(0001) surface is single Fe-terminated. The initial reduction induced by annealing at elevated temperatures produces surface oxygen vacancies, where the excess electrons are localized at adjacent subsurface iron ions (5-fold coordinated). A massive surface restructuring occurs upon further reduction by exposing to atomic hydrogen followed by Ar+-sputtering and annealing under oxygen poor conditions. The restructured surface is identified as a Fe3O4(111)/Fe1−xO(111)-biphase exposing both, Fe3+ and Fe2+ surface species. Here the well-defined surface domains of Fe3O4(111) exhibit a Feoct2-termination, while the reduced Fe1−xO(111) is Fe2+(oct)-terminated. These findings are supported by reference IRRAS data acquired for CO adsorption on magnetite (111) and (001) monocrystalline surfaces.

Photonic crystal (PC) thin films that are self-assembled from different-sized silica microspheres were prepared for studying mechanical properties via nanoindentation at the submicron scale. We found that the silica photonic crystals (PCs) possessed a face-centered cubic (FCC) microstructure and their elastic modulus and hardness were in the range of ~1.81⁻4.92 GPa and 0.008⁻0.033 GPa, respectively. The calculated results proved that there were size-dependent properties in the silica PCs, in that the elastic modulus and hardness increased as the diameter decreased from 538 nm to 326 nm. After studying the total work and plastic work in the progressive deformation of silica PCs during the nanoindentation tests, we developed a two-stage deformation model to explain how the microsphere size affects the mechanical properties of PC thin films. The phenomenon of “smaller is stronger„ is mainly due to the energy consumption, which combines the effects of microstructure collapse, microsphere slide, and reduced porosity during the whole loading and unloading process. In addition, the results of numerical simulation matched the experimental data and reflected the energy change rules of PCs during the indentation process. Furthermore, the study affords useful guidance for constructing high-performance films with proper design and potential application in next-generation PC materials.

Simple sugars produced from a solvent-free mechanocatalytic degradation of cellulose were evaluated for suitability as a growth medium carbon source for fungi that produce volatile organic compounds. An endophytic Hypoxylon sp. (CI-4) known to produce volatiles having potential value as fuels was initially evaluated. The growth was obtained on a medium containing the degraded cellulose as the sole carbon source, and the volatile compounds produced were largely the same as those produced from a conventional dextrose/starch diet. A second Hypoxylon sp. (BS15) was also characterized and shown to be phylogenetically divergent from any other named species. The degraded cellulose medium supported the growth of BS15, and approximately the same quantity of the volatile compounds was produced as from conventional diets. Although the major products from BS15 grown on the degraded cellulose were identical to those from dextrose, the minor products differed. Neither CI-4 or BS15 exhibited growth on cellulose that had not been degraded. The extraction of volatiles from the growth media was achieved using solid-phase extraction in order to reduce the solvent waste and more efficiently retain compounds having low vapor pressures. A comparison to more conventional liquid–liquid extraction demonstrated that, for CI-4, both methods gave similar results. The solid-phase extraction of BS15 retained a significantly larger variety of the volatile compounds than did the liquid–liquid extraction. These advances position the coupling of solvent-free cellulose conversion and endophyte metabolism as a viable strategy for the production of important hydrocarbons.

Certain endophytic fungi belonging to the Hypoxylon genus have recently been found to produce volatile organic compounds (VOCs) that have potential relevance as hydrocarbon fuels. Here, a recently discovered Hypoxylon sp. (BS15) was demonstrated to also produce VOCs, but with diminished VOC production after an extended period of in vitro growth. Restoring VOC production was partially achieved by growing BS15 in growth media containing finely ground woody tissue from the original host plant (Taxodium distichum). In an effort to isolate VOC production modulators, extracts from this woody tissue were made by sequentially extracting with dichloromethane, methanol, and water. Both the dichloromethane and water extracts were found to modulate VOC production, while the methanol extract had no effect. Surprisingly, the woody tissue remaining after exhaustive extraction was also shown to act as a VOC production modulator when included in the growth media, with changes observed in the production of four compounds. This woody tissue also induced production of two compounds not observed in the original BS15 extract. Filter paper had the same modulating effect as exhaustively extracted woody tissue, suggesting the modulation was perhaps due to cellulose degradation products. Overall, this study demonstrated that VOC production in BS15 can be influenced by multiple compounds in the woody tissue rather than a single modulator.

The fast development in the fields of integrated circuits, photovoltaics, the automobile industry, advanced manufacturing, and astronomy have led to the importance and necessity of quickly and accurately obtaining three-dimensional (3D) shape data of specular surfaces for quality control and function evaluation. Owing to the advantages of a large dynamic range, non-contact operation, full-field and fast acquisition, high accuracy, and automatic data processing, phase-measuring deflectometry (PMD, also called fringe reflection profilometry) has been widely studied and applied in many fields. Phase information coded in the reflected fringe patterns relates to the local slope and height of the measured specular objects. The 3D shape is obtained by integrating the local gradient data or directly calculating the depth data from the phase information. We present a review of the relevant techniques regarding classical PMD. The improved PMD technique is then used to measure specular objects having discontinuous and/or isolated surfaces. Some influential factors on the measured results are presented. The challenges and future research directions are discussed to further advance PMD techniques. Finally, the application fields of PMD are briefly introduced.

In the last few years, infrared reflection-absorption spectroscopy (IRRAS) has become a standard technique to study vibrational excitations of molecules. These investigations are strongly motivated by potential applications in monitoring chemical processes. For a better understanding of the adsorption mechanism of molecules on dielectrics, the polarization-dependence of an interaction of infrared light with adsorbates on dielectric surfaces is commonly used. Thus, the peak positions in absorption spectra could be different for s- and p-polarized light. This shift between the peak positions depends on both the molecule itself and the dielectric substrate. While the origin of this shift is well understood for infinite two-dimensional adsorbate layers, finite-size samples, which consist of 2D islands of a small number of molecules, have never been considered. Here, we present a study on polarization-dependent finite-size effects in the optical response of such islands on dielectric substrates. The study uses a multi-scale modeling approach that connects quantum chemistry calculations with Maxwell scattering simulations. We distinguish the optical response of a single molecule, a finite number of molecules, and a two-dimensional adsorbate layer. We analyze CO and CO2 molecules deposited on CeO2 and Al2O3 substrates. The evolution of the shift between the polarization-dependent absorbance peaks is first studied for a single molecule, which does not exhibit any shifting at all, and for finite molecular islands, where it increases with increasing island size, as well as for an infinite two-dimensional adsorbate layer. In the latter case, the agreement between the obtained results and the experimental IRRAS data and more traditional three/four-layer model theoretical studies supports the predictive power of the multi-scale approach. [ABSTRACT FROM AUTHOR]