Search

The warm flow characteristics and microstructural evolution features in a solution-treated 7075 aluminum alloy are revealed. An elastic-visco-plastic constitutive model is developed to capture the flow stress behavior of 7075 aluminum alloy under warm deformation. The variations of microstructure features, including grain and subgrain size, are also analyzed under warm deformation, and are further incorporated in the proposed unified constitutive model. The results indicate that the dynamic recovery (DRV), related to dislocation annihilation and formation/growth of sub-grains, is the domain softening mechanism. The DRV behavior is enhanced at higher temperatures or lower strain rates. Warm external temperature field assists the plastic deformation by means of activating and accelerating the dynamic softening, while the reduced strain rate also gives sufficient time for the softening. Through experimental validation, the proposed constitutive model successfully captures the grain/subgrain features and flow behavior of the studied 7075 aluminum alloy during warm deformation. The predicted result is in a great agreement with the experimental stress-strain data, demonstrating the excellent predictive performance of the model. Moreover, the proposed model also successfully predicts the average grain/subgrain size.

The photocyclization of diarylethenes toward polycyclic aromatic hydrocarbons and analogs has been well‐documented. However, stiff‐stilbene was reported to be inactive, and examples of photocyclization‐induced deamination remain unknown. Here, we report that ortho‐(N,N‐dimethylamino)‐stiff‐stilbene (1a) undergoes efficient photocyclization‐induced deamination, forming the dicyclopenta‐fused phenanthrene (DCPP) with good yield (65%) under anaerobic conditions. The relative reactivities of stiff‐stilbenes with different o‐amino substituents (1b–1g) or with an o‐methoxy (1h) group, and those of o‐(N,N‐dimethylamino)stilbenes (2aand 2aMe), provide insights into the substituent and structural effects. This work demonstrates a new reaction of photocyclization‐ induced deamination with ortho‐dimethylamino‐substituted stiff‐stilbenes under anaerobic conditions, providing an effective route toward the synthesis of dicyclopenta‐fused phenanthrene (DCPP).

The formation of prior particle boundaries (PPBs) in a new powder metallurgy superalloy during hot isostatic pressing (HIP) is investigated. Also, the impact of subsequent hot deformation on the elimination of PPBs is systematically studied. The PPBs involves large γ′ phases, carbides (MC and M6C) and oxides (Al2O3, SiO2and ZrO2). The reactions among the superficial oxides, the adsorbed C and O elements on the particle surface and internally-migrated alloying elements are the dominant reasons for the formation of PPBs during HIP. Besides, the existence of surface tension and surface energy induces the carbon segregation, as well as the formation of PPBs. Thus, the density of PPBs decreases when the spacing between powders is shrunk by a rapid deformation. In hot forming process, the PPBs can be efficiently eliminated via raising deformation temperature/true strain or reducing strain rate. The interactions between dislocations and PPBs, as well as the occurrence of dynamic recrystallization (DRX) induced by the strain/orientation gradient, lead to the elimination of PPBs. The thermodynamic stability of carbides declines with the raised temperature. It indicates that the dissolution of carbides and the elimination of PPBs can be accelerated via raising the deformation temperature. The breakage or deformation behavior of PPBs during hot extrusion is investigated by numerical simulation. The deformation degree of PPBs increases with the raised extrusion ratio. The above important findings are useful for developing hot extrusion processing to effectively eliminate PPBs.

A heavy-chain antibody (VHH) library against procymidone (PRM) was constructed via immunizing Bactriancamels. Through careful biopanning, seven nanobodies (Nbs) with different sequences were obtained. The variability in their performance was primarily attributed to the amino acid differences in complementarity-determining region 3 (CDR3), as analyzed by molecular docking. The Nb exhibiting the highest sensitivity, named NbFM5, was biotinylated and conjugated to streptavidin-labeled gold nanoparticles to preserve the epitope’s activity and prevent a decrease in sensitivity due to traditional random electrostatic adsorption. Subsequently, a simple and sensitive immunochromatographic assay (ICA) was developed for rapid detection of PRM based on biotinylated Nb (btNb). The developed btNb-ICA showed a cut-off value of 200 ng/mL for visual judgment and a half-inhibitory concentration (IC50) of 6.04 ng/mL for quantitative detection. The limit of detection (LOD) was as low as 0.88 ng/mL. The recoveries in actual samples of crops ranged from 82.2 to 117.3%, aligning well with the results obtained from GC–MS/MS (R2= 0.995). In summary, the developed btNb-ICA demonstrated high specificity and good accuracy for the rapid detection of PRM residues in vegetables. The total analysis time from preparing the sample to obtaining the result was less than 25 min.

Photoinduced electron-transfer (PET) immunoassay based on a fluorescence site-specifically labeled nanobody, also called mini Quenchbody (Q-body), exhibits extraordinary sensitivity and saves much time in the homogeneous noncompetitive mode and is therefore regarded as a valuable method. However, limited by the efficiency of both quenching and dequenching of the fluorescence signal before and after antigen binding associated with the PET principle, not all original nanobodies can be used as candidates for mini Q-bodies. Herein, with the anti-quinalphos nanobody 11A (Nb-11A) as the model, we, for the first time, adopt a strategy by combining X-ray structural analysis with site-directed mutagenesis to design and produce a mutant Nb-R29W, and then successfully generate a mini Q-body by labeling with ATTO520 fluorescein. Based on this, a novel PET immunoassay is established, which exhibits a limit of detection of 0.007 μg/mL with a detection time of only 15 min, 25-fold improved sensitivity, and faster by 5-fold compared to the competitive immunoassay. Meanwhile, the recovery test of vegetable samples and validation by the standard ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) both demonstrated that the established PET immunoassay is a novel, sensitive, and accurate detection method for quinalphos. Ultimately, the findings of this work will provide valuable insights into the development of triggered PET fluorescence probes by using existing antibody resources.

We report herein a new rotation‐inversion dual‐motion molecular switch (1), in which a 3,3‐dimethylazetidinyl (DMAZ) group is the rotator and a stiff‐stilbene is the helical stator. There are two sets of nuclear magnetic resonance (NMR) signals in the DMAZ group, the H‐shaped AZprotons and the planar C2‐symmetrical Meprotons, for probing the kinetics of the DMAZ rotation and the stiff‐stilbene inversion. While the two motion modes are highly correlated in (E)‐1, they are decoupled in (Z)‐1. The rotation‐inversion correlated motion in (E)‐1is governed by the faster inversion mode, whereas the inversion is much slower than the rotation in (Z)‐1. Consequently, photochemical isomerization between (E)‐1and (Z)‐1switches not only the relative rate of the rotation versus inversion motion but also the on–off behavior of the rotation‐inversion correlated motion. This work shows the cooperation of two sets of proton signals in elucidating the correlated motion in a dual‐motion molecular system. The dimethylazetidinyl rotator, which contains both the H‐shaped and the C2‐planar NMR proton signals, in 1is able to probe the rotation‐inversion correlated motion in (E)‐1and the independent rotation kinetics in (Z)‐1.

Highly crosslinked ultrahigh-molecular-weight polyethylene (UHMWPE) bearings are wear-resistant to reduce aseptic loosening but are susceptible to oxidize in vivo/in vitro, as reported in clinical studies. Despite widespread acceptance of antioxidants in preventing oxidation, the crosslinking efficiency of UHMWPE is severely impacted by antioxidants, the use of which was trapped in a trace amount. Herein, we proposed a new strategy of polyphenol-assisted chemical crosslinking to facilitate the formation of a crosslinking network in high-loaded tea polyphenol/UHMWPE blends. Epigallocatechin gallate (EGCG), a representative of tea polyphenol, was mixed with UHMWPE and peroxide. Multiple reactive phenolic hydroxyl groups of tea polyphenol coupled with the nearby free radicals to form extra crosslinking sites. The crosslinking efficiency was remarkably enhanced with increasing tea polyphenol content, even at a concentration of 8 wt %. Given by the hydrogen donation principle, the high-loaded tea polyphenol also enhanced the oxidation stability of the crosslinked UHMWPE. The antioxidative performance was preserved even after tea polyphenol elution. Moreover, superior antibacterial performance was achieved by the in situ tea polyphenol release from the interconnected pathways in the present design. The strategy of polyphenol-assisted chemical crosslinking is applicable for producing highly crosslinked, antioxidative, and antibacterial UHMWPE, which has promising prospects in clinical applications.

Diazinon (DAZ) is an organophosphorus pesticide (OP), which is commonly used to prevent and control harmful pests that endanger agricultural products. In this study, we developed a novel heterology coating strategy for the immunoassay of DAZ. The DAZ coating hapten can be directly conjugated to the carrier protein without requiring a spacer arm. This proposed hapten coating strategy is time-saving and significantly improves the sensitivity of the immunoassay due to the lack of a spacer arm. The as-synthesized coating antigen was used to screen the monoclonal antibody (mAb). Finally, the developed indirect competitive enzyme-linked immunoassay (icELISA) showed IC50and limit of detection (LOD) values of 0.58 ng mL−1and 8 pg mL−1, respectively. This method exhibited negligible cross-reactivity towards other analogues, and the recoveries of samples (cucumber, cabbage, and lettuce) ranged from 92.6% to 125.4%, with coefficients of variance (CV) below 12%. Good correlation between icELISA and high-performance liquid chromatography mass spectrometry (HPLC-MS/MS) was obtained. The proposed icELISA was an ideal tool for monitoring DAZ residues in food samples.

Probing the inversion kinetics of a molecular helix is inherently a challenging task. We demonstrate herein that a fast-rotating pentiptycene component could function as an external NMR probe to afford the kinetic information on the inversion of a neighboring helical stiff-stilbene unit.

Melatonin (MT) is an endogenous hormone that is used in medicinal foods for all kinds of purposes. Monitoring the content of MT is necessary to guarantee the quality of medicinal foods, as well as to prevent it from being abused. In this work, an easy-to-use and low-cost competitive indirect ELISA with a flexible working range for monitoring MT was developed. Four haptens were synthesized and coupled to carrier proteins as immunogens to compare their ability to generate antibodies against MT. After screening the antisera and optimizing the working conditions, a homologous ELISA with a limit of detection (LOD) of 30.85 ng mL−1and a wide working range from 66.2 ng mL−1to 65.9 μg mL−1, and a heterologous ELISA with an LOD of 0.21 ng mL−1and a working range from 1.0 ng mL−1to 104.4 ng mL−1for MT were developed. Using the homologous format, the developed ELISA is easy-to-use for the quantitative determination of MT in a medicinal food matrix, with the recovery ranging from 84% to 113.6%. Good correlation between the results of the ELISA and standard liquid chromatography (LC) was obtained. The proposed two ELISA formats are ideal tools for screening a large number of medicinal food samples for MT prior to standard instrumental analysis.

Periodontitis is a worldwide bacterial infectious disease, resulting in the resorption of tooth-supporting structures. Biodegradable polymeric microspheres are emerging as an appealing local therapy candidate for periodontal defect regeneration but suffer from tedious procedures and low yields. Herein, we developed a facile yet scalable approach to prepare polylactide composite microspheres with outstanding drug-loading capability. It was realized by blending equimolar polylactide enantiomers at the temperature between the melting point of homocrystallites and stereocomplex (sc) crystallites, enabling the precipitation of sc crystallites in the form of microspheres. Meanwhile, epigallocatechin gallate (EGCG) and nano-hydroxyapatite were encapsulated in the microspheres in the designated amount. Such an assembly allowed the fast and sustained release of EGCG and Ca2+ions. The resultant hybrid composite microspheres not only exhibited strong antimicrobial activity against typical oral pathogens (Porphyromonas gingivalisand Enterococcus faecalis), but also directly promoted osteogenic differentiation of periodontal ligament stem cells with good cytocompatibility. These dual-functional composite microspheres offer a desired drug delivery platform to address the practical needs for periodontitis treatment.

A simple and sensitive fluoroimmunoassay (FIA) based on a heavy-chain antibody (VHH) for rapid detection of fenitrothion was developed. A VHH library was constructed from an immunized alpaca, and one clone recognizing fenitrothion (namely, VHHjd8) was achieved after careful biopanning. It was biotinylated by fusing with the Avi tag and biotin ligase to obtain a fusion protein (VHHjd8-BT), showing both binding capacity to fenitrothion and the streptavidin poly-horseradish peroxidase conjugate (SA-polyHRP). Based on a competitive assay format, the absorbance spectrum of oxidized 3,3′,5,5′-tetramethylbenzidine generated by SA-polyHRP overlapped the emission spectrum of carbon dots, which resulted in quenching of signals due to the inner-filter effect. The developed FIA showed an IC50value of 1.4 ng/mL and a limit of detection of 0.03 ng/mL, which exhibited 15-fold improvement compared with conventional enzyme-linked immunosorbent assay. The recovery test of FIA was validated by standard GC–MS/MS, and the results showed good consistency, indicating that the assay is an ideal tool for rapid screening of fenitrothion in bulk food samples.

The interplay between the thermal helical inversion (THI) of the stiff-stilbene moiety and the rotation of the dimethylamino (DMA) group in 1results in a dependence of the DMA NMR signals on the THI kinetics in (E)-1but the rotation kinetics in (Z)-1, because the faster motion mode is responsible. Consequently, the photochemical switching from (E)-1to (Z)-1illustrates the phenomenon of “switchable motion detection” by the same set of NMR signals in a dual-motion molecular system.

This paper proposed a brand new design method highly fitting architectural design concepts with green building spirit through the real example of Hefei University Library and the return visit after the completion of the building, to provide a new direction of thinking for the construction of university green buildings.

The paper takes the design of the Sports Center of Zhaoqing High-tech Zone as an example to put forward an architectural design strategy which is mainly aimed at saving land and improving outdoor environment, and then to list some concrete strategies and discuss the land-conservation strategies application meaning in the field of public construction, especially in the field of public sports construction.

Considering the combined action of the fluid penetration and the casing, the seepage coupled deformation finite element model of the highly deviated casing perforation well is established by using the tensile strength failure criterion and applied on the BZ25-1 oil filed. The results show that the increasing of the perforation angle and the well azimuth and the decreasing of the inclination would lead to a higher fracture initiation pressure. The fracture initiation point always locates on the wellbore face when the influence of the casing is considered. When the casing is ignored: when the perforation angle is 0°-45°, the fracture initiation point locates on the root of the tunnel; when the angle is 45°-90°, the fracture initiation point may be on the wellbore face or the perforation biased toward the maximum horizontal stress direction; when the angle is near to 90°, the hydraulic fracturing difficultly fractures the rock through the perforation tunnels. The laboratory hydraulic fracturing simulation experiments of 45° deviated well are carried through 400mm3 cement specimen so as to obtain the fracture initiation point and geometric shape under different perforation angles, the results verify the accuracy of the numerical simulation method.

Mycotoxins are toxic contaminants in foods and feeds that are naturally occurring and largely unavoidable. Determining their contents in these products is essential to protect humans from harm. Immunoassays of mycotoxins have been well-established because they are fast, sensitive, simple, and cost-effective. However, a major limitation of immunoassays is the requirement of toxic mycotoxins as competing antigens, standards, or competing tracers. Mimotopes are peptides or proteins that can specifically bind to antibodies and compete with analytes for binding sites by mimicking antigenic epitopes. They can be employed as substitutes for competing antigens, standards, or competing tracers to avoid use of mycotoxins. This review summarizes the production and functionalization of the two main kinds of mimotopes, mimic peptides and anti-idiotypic antibodies (Ab2), and their applications in rapid analysis of mycotoxins.

Cysteine-rich secretory protein 2 (CRISP2) is an important sperm protein and plays roles in spermatogenesis, modulation of flagellar motility, acrosome reaction, and gamete fusion. Clinical evidence shows a reduced CRISP2expression in spermatozoa from asthenozoospermic patients, but the molecular mechanism underlying its reduction remains unknown. Herein, we carried out a study focusing on the CRISP2reduction and its roles in asthenozoospermia. Initially, through analyzing CRISP2expression and methylation on CRISP2promoter activity in sperm, we observed a decreased expression of CRISP2 protein rather than its mRNA in the ejaculated spermatozoa from asthenozoospermic patients and no methylation in the CRISP2promoter, suggesting CRISP2expression may be regulated in the sperm at the posttranscriptional level. Subsequently, we found that microRNA 27b (miR-27b), predicted as a candidate regulator of CRISP2using bioinformatics, was highly expressed in the ejaculated spermatozoa from asthenozoospermic patients. Luciferase reporter assay and transfection experiments disclosed that this microRNA could target CRISP2by specifically binding its 3′ untranslated region, suppressing CRISP2expression. Extended clinical observation further confirmed a highly expressed miR-27b and its obviously negative correlation with CRISP2 protein expression in ejaculated spermatozoa samples from asthenozoospermic patients. Finally, we conducted a retrospective follow-up study to support that either high miR-27b expression or low CRISP2 protein expression was significantly associated with low sperm progressive motility, abnormal morphology, and infertility. Thus, this study provides the first preliminary insight into the mechanism leading to the reduced CRISP2 expression in asthenozoospermia, offering a potential therapeutic target for treating male infertility or for male contraception.