ABSTRACT
With the tertiary oil recovery in the oilfield, the content of aging oil emulsion with high water content and complex components has become more prevalent, so it is crucial for aging oil to break the emulsification. In this paper, the experimental laws of water content are explored under the conditions of different transducer input powers through the ultrasonic reforming of aging oil, and the microscopic topography, particle size, components, etc. of oil samples before and after the irradiation of ultrasound are characterized through the microscopic analysis, particle size analysis and component analysis and other ways. The results show that the oil samples achieve the effect of demulsification and dehydration in the presence of ultrasonic cavitation effect, with a maximum dehydration rate of 98.24 %, and that the dehydration rate follows an "M-type" trend with the increase of power. The results of microscopic and particle size analyses demonstrate that ultrasonic irradiation destabilizes the oil-water interfacial membrane, and causes droplets of different sizes to collide, agglomerate, and settle. It was also observed that the droplets of the emulsion system are more evenly distributed and the intervals are increased. Furthermore, we hypothesize that ultrasound may be less irreversible in demulsification and dehydration of aging oil.
ABSTRACT
Utilizing the mercury (Hg2+)-triggered deprotection of thioacetals to aldehyde groups, we constructed a water-soluble triphenylamine (TPA)-based polythioacetal PTA-TPA with thioacetal groups in the backbones for efficient sensing of Hg2+ in aqueous solutions. PTA-TPA is conveniently prepared by polycondensation of 3, 6-dioxa-1,8-octanedithiol (DODT) with 4-(N,N-diphenylamino) benzaldehyde (TPA-CHO) using thiol-terminated mPEG2k-SH as a capping agent. The interaction of Hg2+ with PTA-TPA activates the aggregation-induced emission (AIE) process of TPA-CHO molecules, which makes the emission enhanced, and the emission color changes to sky blue, while other metal ions do not interfere with the sensing process. PTA-TPA can be used as a highly selective and ultrafast detection system for Hg2+ with a low detection limit (LOD) of 9.88 nM and a fast response of less than 1 min. In addition, the prepared test strips report the presence of Hg2+ with an LOD as low as 1 × 10-5 M. Intracellular imaging applications have demonstrated that PTA-TPA acts as a biocompatible fluorescent probe for efficient Hg2+ sensing in HeLa cells. Overall, the PTA-TPA fluorescence probes have the characteristics of easy synthesis, cost-effective, ultrafast detection speed, high selectivity, and high sensitivity, which can be used in practical applications.
ABSTRACT
Necrotizing fasciitis is a rare, severe, rapidly progressing disease with a high mortality rate. We report a case of a 72-year female with erythematous pemphigus who developed erythema, swelling and ulceration on right vulva, groin, and thigh. The early clinical manifestations of the patient were nonspecific and easily misdiagnosed as cellulitis. However, upon the occurrence of ulceration and necrosis, deep fungal infection, pyoderma gangrenosum or lymphoproliferative disorders were considered. The pathology suggested IgG4-related diseases, plasmacytoma et al. But at last, surgical exploration and postoperative pathology confirmed the diagnosis of necrotizing fasciitis. The patient recovered after multiple aggressive surgical debridement procedures and antibiotic therapy and the patient has been followed up for 2 years without recurrence. Clinicians should be vigilant about the possibility of necrotizing fasciitis in patients with erythema, pain, rapid ulceration of skin and soft tissue, particularly in immunocompromised individuals with long-term use of immunosuppressive agents. It is crucial for saving life by early multi-disciplinary consultation, prompt diagnosis, and aggressive treatment.
ABSTRACT
A water-soluble polymeric pyrene-based polythioacetal (PTA-Py) with thioacetal units in the main chain is simply synthesized by direct polycondensation of 3, 6-dioxa-1, 8-octanedithiol, 1-pyrene formaldehyde, and mPEG2k-SH. The probe PTA-Py shows a good fluorescence response to Hg2+ ions due to the Hg2+-promoted deprotection reaction of thioacetal groups to regenerate the original 1-pyrene formaldehyde compound. After adding Hg2+ to the PTA-Py solution, the fluorescence intensity (FI) gradually increases with increasing concentrations of Hg2+. Compared with other metal ions, the probe exhibits high sensitivity, good selectivity, and rapid response to Hg2+. The low detection limits are 12.3 nm in ethanol-PBS buffer and 13.3 nm in water, respectively. The results imply that the simply synthesized water-soluble polymeric probe had potential applications in the rapid detection of Hg2+ ions in aqueous solutions. Moreover, the polymeric PTA-Py shows high sensitivity for CH3Hg+ with detection limits of 26.5 nm in ethanol/PBS buffer. In addition, PTA-Py can efficiently detect Hg2+ ions in HeLa cells. The results demonstrate that a valuable method is developed for biocompatible polymeric sensors for Hg2+ ions in biological and environmental samples.
Subject(s)
Mercury , Humans , Fluorescent Dyes , HeLa Cells , Water , Pyrenes , Polymers , Ions , Spectrometry, Fluorescence , Ethanol , FormaldehydeABSTRACT
BACKGROUND: Data on nail psoriasis (PsO) in China are scarce. OBJECTIVES: To provide nail PsO-related data regarding epidemiologic characteristics, manifestations, fungal infections, arthritic complaints and treatments that may facilitate improved patient management globally. METHODS: From August 2021 to August 2022, patients with nail PsO were enrolled in a prospective multicentre observational study at 25 hospitals in China. We collected and analysed data concerning nail PsO demography, clinical signs, fungal detection, arthritic symptoms and treatment. RESULTS: A total of 817 patients with nail PsO were involved, with a mean body mass index of 24.13 ± 2.93. In addition, 71.41% of the patients were male. The Nail PsO Severity Index score was weakly positively correlated with body surface area. The percentage of nail involvement was 95.29% for fingernails and 57.18% for toenails, with pitting (67.11%) and subungual hyperkeratosis (60.40%) being the most prevalent manifestations, respectively. Toenails showed a significantly higher frequency of nailfold scales, subungual hyperkeratosis and nail plate crumbling and a lower frequency of splinter haemorrhages, pitting and erythema of the lunula. A total of 13.26% of the PsO patients had onychomycosis, and 77.08% were observed in the toenails. Articular symptoms were reported by 12.17% of the patients, with the peripheral type being predominant. Significant associations between articular symptoms and nailfold swelling, subungual hyperkeratosis, nailfold scales, onycholysis and longitudinal ridges were found. Only 2.30% (20 out of 871) of patients with nail PsO received treatment. The most frequently employed therapy for cutaneous PsO with nail involvement was biologic therapy (n = 366). CONCLUSIONS: PsO showed distinct manifestations in the toenails and fingernails. Additionally, toenail PsO combined with onychomycosis requires special attention. Articular symptoms in psoriatic patients are associated with specific nail changes. It is important to research and advocate for more potent treatments for nail PsO.
Subject(s)
Nail Diseases , Onychomycosis , Psoriasis , Humans , Male , Female , Onychomycosis/diagnosis , Prospective Studies , Nail Diseases/diagnosis , Psoriasis/epidemiology , Psoriasis/therapy , Psoriasis/complications , China/epidemiologyABSTRACT
A lingering question in developmental biology has centered on how transcription factors with widespread distribution in vertebrate embryos can perform tissue-specific functions. Here, using the murine hindlimb as a model, we investigate the elusive mechanisms whereby PBX TALE homeoproteins, viewed primarily as HOX cofactors, attain context-specific developmental roles despite ubiquitous presence in the embryo. We first demonstrate that mesenchymal-specific loss of PBX1/2 or the transcriptional regulator HAND2 generates similar limb phenotypes. By combining tissue-specific and temporally controlled mutagenesis with multi-omics approaches, we reconstruct a gene regulatory network (GRN) at organismal-level resolution that is collaboratively directed by PBX1/2 and HAND2 interactions in subsets of posterior hindlimb mesenchymal cells. Genome-wide profiling of PBX1 binding across multiple embryonic tissues further reveals that HAND2 interacts with subsets of PBX-bound regions to regulate limb-specific GRNs. Our research elucidates fundamental principles by which promiscuous transcription factors cooperate with cofactors that display domain-restricted localization to instruct tissue-specific developmental programs.
Subject(s)
Gene Regulatory Networks , Transcription Factors , Animals , Mice , Homeodomain Proteins/metabolism , Pre-B-Cell Leukemia Transcription Factor 1/genetics , Transcription Factors/genetics , Transcription Factors/metabolismABSTRACT
BACKGROUND: Psoriasis is one of the most frequent inflammatory skin conditions and could be treated via tele-dermatology, provided that the current lack of reliable tools for objective severity assessments is overcome. Psoriasis Area and Severity Index (PASI) has a prominent level of subjectivity and is rarely used in real practice, although it is the most widely accepted metric for measuring psoriasis severity currently. OBJECTIVE: This study aimed to develop an image-artificial intelligence (AI)-based validated system for severity assessment with the explicit intention of facilitating long-term management of patients with psoriasis. METHODS: A deep learning system was trained to estimate the PASI score by using 14,096 images from 2367 patients with psoriasis. We used 1962 patients from January 2015 to April 2021 to train the model and the other 405 patients from May 2021 to July 2021 to validate it. A multiview feature enhancement block was designed to combine vision features from different perspectives to better simulate the visual diagnostic method in clinical practice. A classification header along with a regression header was simultaneously applied to generate PASI scores, and an extra cross-teacher header after these 2 headers was designed to revise their output. The mean average error (MAE) was used as the metric to evaluate the accuracy of the predicted PASI score. By making the model minimize the MAE value, the model becomes closer to the target value. Then, the proposed model was compared with 43 experienced dermatologists. Finally, the proposed model was deployed into an app named SkinTeller on the WeChat platform. RESULTS: The proposed image-AI-based PASI-estimating model outperformed the average performance of 43 experienced dermatologists with a 33.2% performance gain in the overall PASI score. The model achieved the smallest MAE of 2.05 at 3 input images by the ablation experiment. In other words, for the task of psoriasis severity assessment, the severity score predicted by our model was close to the PASI score diagnosed by experienced dermatologists. The SkinTeller app has been used 3369 times for PASI scoring in 1497 patients from 18 hospitals, and its excellent performance was confirmed by a feedback survey of 43 dermatologist users. CONCLUSIONS: An image-AI-based psoriasis severity assessment model has been proposed to automatically calculate PASI scores in an efficient, objective, and accurate manner. The SkinTeller app may be a promising alternative for dermatologists' accurate assessment in the real world and chronic disease self-management in patients with psoriasis.
Subject(s)
Artificial Intelligence , Psoriasis , Humans , Severity of Illness Index , Psoriasis/diagnosis , Chronic Disease , Surveys and QuestionnairesABSTRACT
Limb patterning by Sonic hedgehog (Shh), via either graded spatial or temporal signal integration, is a paradigm for "morphogen" function, yet how Shh instructs distinct digit identities remains controversial. Here, we bypass the Shh requirement in cell survival during outgrowth and demonstrate that a transient, early Shh pulse is both necessary and sufficient for normal mouse limb development. Shh response is only short range and is limited to the Shh-expressing zone during this time window. Shh patterns digits 1-3, anterior to this zone, by an indirect mechanism rather than direct spatial or temporal signal integration. Using a genetic relay-signaling assay, we discover that Shh also specifies digit 1/thumb (thought to be exclusively Shh independent) indirectly, and this finding implicates Shh in a unique regulatory hierarchy for digit 1 evolutionary adaptations such as opposable thumbs. This study illuminates Shh as a trigger for an indirect downstream network that becomes rapidly self-sustaining, with mechanistic relevance for limb development, regeneration, and evolution.
Subject(s)
Body Patterning , Hedgehog Proteins , Animals , Body Patterning/genetics , Extremities , Gene Expression Regulation, Developmental , Hedgehog Proteins/genetics , Hedgehog Proteins/metabolism , Mice , Signal TransductionABSTRACT
Taking the entire education system in Taiyuan City, Shanxi Province, Central China, as an example, this paper uses the questionnaire survey method to analyze the effect of artificial intelligence (AI) on role cognition in the education system. The education system targeted by this questionnaire survey involves 8 categories: preschool education, primary education, secondary education, higher education, adult education, computer network education, enterprise education, and social education; the respondents include 368 teachers, 402 students or learners, 118 school managers, and 124 family members of students or learners in all above education categories. The questionnaire design has a total of 34 question classified into 6 role cognition items, with a 5-level score; a total of 1012 questionnaires were distributed, and 978 were recovered with a recovery rate of 96.64%, in which 957 were valid questionnaires with an effective rate of 97.85%. The study results show that the learning of AI-assisted courses is strongly dependent on course role cognition, and the construction of role cognition is related to the understanding of course content, teaching methods, and activity methods. Therefore, the effect of AI on role cognition in the education system needs to be systematically analyzed from the aspects of function realization form, resource presentation method, supporting hardware form, teacher-student interaction method, and representation method of works. As connecters, teacher's role cognition is limited by the degree of understanding learners, the amount of resources, and data processing capabilities, but the advantage is that they can flexibly monitor and adjust. AI technology is flexible and diverse, it functions in learning and teaching activities in a variety of ways, and there is no agreement on the terminology to describe its role in role recognition. The results of this paper provide a reference for further researches on the effect of AI on role cognition in the education system.
Subject(s)
Artificial Intelligence , Occupational Therapy , Adult , Child, Preschool , Cognition , Humans , Learning , StudentsABSTRACT
Coded aperture X-ray computed tomography is a computational imaging technique capable of reconstructing inner structures of an object from a reduced set of X-ray projection measurements. Coded apertures are placed in front of the X-ray sources from different views and thus significantly reduce the radiation dose. This paper introduces coded aperture X-ray computed tomography for robotic X-ray systems which offer positioning flexibility. While single coded-aperture 3D tomography was recently introduced for standard trajectory CT scanning, it is shown that significant gains in imaging performance can be attained by simple modifications in the CT scanning trajectories enabled by emerging dual robotic CT systems. In particular, the subject is fixed on a plane and the CT system uniformly rotates around the r -axis which is misaligned with the coordinate axes. A single stationary coded aperture is placed on front of the robotic X-ray source above the plane and the corresponding X-ray projections are measured by a two-dimensional detector on the second arm of the robotic system. The compressive measurements with misalignment enable the reconstruction of high-resolution three-dimensional volumetric images from the low-resolution coded projections on the detector at a sub-sampling rate. An efficient algorithm is proposed to generate the rotation matrix with two basic sub-matrices and thus the forward model is formulated. The stationary coded aperture is designed based on the Pearson product-moment correlation coefficient analysis and the direct binary search algorithm is used to obtain the optimized coded aperture. Simulations using simulated datasets show significant gains in reconstruction performance compared to conventional coded aperture CT systems.
ABSTRACT
In most tetrapod vertebrates, limb skeletal progenitors condense with postaxial dominance. Posterior elements (such as ulna and fibula) appear prior to their anterior counterparts (radius and tibia), followed by digit-appearance order with continuing postaxial polarity. The only exceptions are urodele amphibians (salamanders), whose limb elements develop with preaxial polarity and who are also notable for their unique ability to regenerate complete limbs as adults. The mechanistic basis for this preaxial dominance has remained an enigma and has even been proposed to relate to the acquisition of novel genes involved in regeneration. However, recent fossil evidence suggests that preaxial polarity represents an ancestral rather than derived state. Here, we report that 5'Hoxd (Hoxd11-d13) gene deletion in mouse is atavistic and uncovers an underlying preaxial polarity in mammalian limb formation. We demonstrate this shift from postaxial to preaxial dominance in mouse results from excess Gli3 repressor (Gli3R) activity due to the loss of 5'Hoxd-Gli3 antagonism and is associated with cell-cycle changes promoting precocious cell-cycle exit in the anterior limb bud. We further show that Gli3 knockdown in axolotl results in a shift to postaxial dominant limb skeleton formation, as well as expanded paddle-shaped limb-bud morphology and ensuing polydactyly. Evolutionary changes in Gli3R activity level, which also played a key role in the fin-to-limb transition, appear to be fundamental to the shift from preaxial to postaxial polarity in formation of the tetrapod limb skeleton.
Subject(s)
Extremities , Limb Buds , Animals , Biological Evolution , Extremities/anatomy & histology , Mammals , Mice , Transcription Factors/genetics , Urodela/anatomy & histologyABSTRACT
BACKGROUND: Tyrosinase-positive oculocutaneous albinism (OCA, type II, OCA2) is an autosomal recessive genetic disease in which the biosynthesis of melanin decreases in the skin, hair, and eyes. OCA2 disease is caused by mutations in OCA2 gene. The gene product plays a role in regulating the pH of melanosomes. Up to now, hundreds of OCA2 mutations have been reported and novel variants are still being discovered. METHODS: In this study, we reviewed the records of OCA2 patients who had conducted albinism genetic testing, and then analyzed the clinical and genetic information of 28 OCA2 patients who had been genetically diagnosed by using Sanger sequencing and next-generation sequencing. RESULTS: In this study, we reported 31 variants screened from 28 Chinese OCA2 families, and characterized the detailed molecular and clinical presentations. There were 12 novel variants among all detected variants, including 3 missense variants (p.G393V, p.T482A, and p.R720P), 4 frameshift variants (p.R53Gfs∗49, p.N279Kfs∗17, p.I469Lfs∗4, p.I655Nfs∗12), 2 splicing variants (c.1637-2A > G, c.1951 + 1G > C), 2 stopgain variants (p.L278X, p.W652X) and 1 insertion variants (p.P315LinsT). One potential cluster of missense variants was implicated indicating the important roles of the underlying domains in OCA2 pathogenesis. CONCLUSION: Our results were beneficial for diagnosis and precision clinical management for OCA2-related disorder, and this study expanded the mutation spectrum of oculocutaneous albinism.
ABSTRACT
Delamination is the most common and dangerous failure mode for multilayered structures. Delamination defects of different shapes and sizes have different sensitivity to guided wave of different frequencies and modes. So that it is necessary to study the application of multi-frequency methods for achieving detection. In this study, the algorithm of multi-frequency localized wave energy is present using laser ultrasonic guided waves for delamination identification. Localized wave energy is acoustic energy in space under specific wavenumber. New wavenumber components occur in damaged composite plates and its localized wave energy can be used for delamination identification. The localized wave energy is not only related to mode conversion caused by the decrease of structural thickness above the delamination, but also the scattering waves in delamination region. The scattering waves make acoustic energy redistributed and it is enhanced at specific spatial position. The discovery has been verified in simulation and experiment. Multi-frequency experimental results show lower noises and more discernible profile of delamination region in two specimens, including medial and non-medial delamination. In the case of medial delamination, the actual dispersion curve is closer to the dispersion curve of upper laminate at high frequency; in the case of non-medial delamination, the actual dispersion curve is similar to the ideal situation ignoring the effect of epoxy resin. Based on the actual dispersion curves, two critical parameters of proper frequencies and filter threshold are selected for delamination identification using laser ultrasonic guided wave.
ABSTRACT
Because of the advantages of high specific strength and high specific stiffness, carbon fiber reinforced plastics (CFRP) have been the most ideal materials in the field of civil aviation. Cure monitoring in manufacturing process and damage identification in service stage of CFRP are always hot topics. The Semi-Analytical Finite Element (SAFE) method and micromechanical model are employed to analyse the propagation characteristics of the Lamb-like waves in a continuous flat aluminium plate attached to a viscoelastic unidirectional CFRP in semi-infinite half-space. Then the vacuum bag moulding process of prepregs is monitored using Fiber Bragg Grating (FBG) and piezoelectric sensors encapsulated in Stanford Multiactuator-Receiver Transduction (SMART) Layer. The calculated energy velocities and attenuations of guided waves show the same trends with the numerical results while curing. After the CFRP is demoulded, the damage identification experiments are carried out. By continuing to use the sensor network embedded in the manufacturing phase, the artificial damages can be precisely located. The results demonstrated that the life-cycle monitoring of CFRP can be achieved effectively by the piezoelectric sensors network.
ABSTRACT
The electromechanical impedance model of the piezoelectric ceramics in a free state can be used for screening and quality control in the structural health monitoring community, but the derivation process of the existing model is usually complicated. This paper describes a novel theoretical derivation methodology based on the assumption of zero-stress on the free boundary of the one-dimensional transducer, which can simplify the derivation of the model to a large extent. To assess the accuracy of the model, a signal processing method based on frequency shifting transformation and the Pearson correlation coefficient is also proposed to calculate the similarity between theoretically predicted and experimentally measured data. Two different piezoelectric ceramics were used in experiments to verify the effectiveness of the model. Experimental results convincingly demonstrate that the assumption proposed in this paper possesses good feasibility for one-dimensional thin-walled piezoelectric ceramics and the model has excellent precision.
ABSTRACT
Despite the importance of Wnt signaling for adult intestinal stem cell homeostasis and colorectal cancer, relatively little is known about its role in colon formation during embryogenesis. The development of the colon starts with the formation and extension of the hindgut. We show that Wnt3a is expressed in the caudal embryo in a dorsal-ventral (DV) gradient across all three germ layers, including the hindgut. Using genetic and lineage-tracing approaches, we describe novel dorsal and ventral hindgut domains, and show that ventrolateral hindgut cells populate the majority of the colonic epithelium. A Wnt3a-ß-catenin-Sp5/8 pathway, which is active in the dorsal hindgut endoderm, is required for hindgut extension and colon formation. Interestingly, the absence of Wnt activity in the ventral hindgut is crucial for proper hindgut morphogenesis, as ectopic stabilization of ß-catenin in the ventral hindgut via gain- or loss-of-function mutations in Ctnnb1 or Apc, respectively, leads to severe colonic hyperplasia. Thus, the DV Wnt gradient is required to coordinate growth between dorsal and ventral hindgut domains to regulate the extension of the hindgut that leads to colon formation.
Subject(s)
Body Patterning , Colon/embryology , Colon/metabolism , Wnt Signaling Pathway , Wnt3A Protein/metabolism , beta Catenin/metabolism , Animals , Bone Morphogenetic Proteins/metabolism , Cell Proliferation , Embryo, Mammalian/metabolism , Gene Expression Regulation, Developmental , Mice, Transgenic , MorphogenesisABSTRACT
In the tetrapod limb, the digits (fingers or toes) are the elements most subject to morphological diversification in response to functional adaptations. However, despite their functional importance, the mechanisms controlling digit morphology remain poorly understood. Here we have focused on understanding the special morphology of the thumb (digit 1), the acquisition of which was an important adaptation of the human hand. To this end, we have studied the limbs of the Hoxa13 mouse mutant that specifically fail to form digit 1. We show that, consistent with the role of Hoxa13 in Hoxd transcriptional regulation, the expression of Hoxd13 in Hoxa13 mutant limbs does not extend into the presumptive digit 1 territory, which is therefore devoid of distal Hox transcripts, a circumstance that can explain its agenesis. The loss of Hoxd13 expression, exclusively in digit 1 territory, correlates with increased Gli3 repressor activity, a Hoxd negative regulator, resulting from increased Gli3 transcription that, in turn, is due to the release from the negative modulation exerted by Hox13 paralogs on Gli3 regulatory sequences. Our results indicate that Hoxa13 acts hierarchically to initiate the formation of digit 1 by reducing Gli3 transcription and by enabling expansion of the 5'Hoxd second expression phase, thereby establishing anterior-posterior asymmetry in the handplate. Our work uncovers a mutual antagonism between Gli3 and Hox13 paralogs that has important implications for Hox and Gli3 gene regulation in the context of development and evolution.
Subject(s)
Extremities/growth & development , Homeodomain Proteins/metabolism , Nerve Tissue Proteins/metabolism , Transcription Factors/metabolism , Zinc Finger Protein Gli3/metabolism , Animals , Body Patterning , Gene Expression Regulation, Developmental , Homeodomain Proteins/genetics , Mice , Mice, Inbred C57BL , Mice, Knockout , Nerve Tissue Proteins/genetics , Transcription Factors/genetics , Transcriptome , Zinc Finger Protein Gli3/geneticsABSTRACT
The single-lap joint of fiber-reinforced composites is a common structure in the field of structure repair, which has excellent mechanical properties. To study and monitor its quasi-static response behavior under external load, two methodologies called effective structural mechanical impedance (ESMI) and reduced-ESMI (R-ESMI) are presented in this article. A two-dimensional electromechanical impedance (EMI) model for a surface-bonded square piezoelectric transducer (PZT) is adopted to extract more sensitive signatures from the measured raw signatures. There are two major advantages of the monitoring scheme based on ESMI and R-ESMI signatures: (1) excellent monitoring results with less signatures to process, (2) the ability to monitor the quasi-static behavior of a single-lap joint with previously ignored susceptance signatures. Combining the extracted ESMI signatures with the index of root-mean-square deviation, the quasi-static behavior of single-lap joints can be effectively quantified. To test the effectiveness of ESMI methodology, verifying experiments were conducted. The experimental results convincingly demonstrated that the presented ESMI and R-ESMI methodologies have good feasibility in monitoring the quasi-static behavior of a fiber-reinforced composite single-lap joint. The proposed method has potential application in the field of structural health monitoring (SHM).
ABSTRACT
In order to monitor the health condition of structures in a more sensitive and accurate way, a novel and universal methodology called direct coupling mechanical impedance (DCMI) for characteristic signatures extraction is presented in this paper. This methodology is used to obtain DCMI signatures from measured raw signatures (RSs) with the surface-bonded piezoelectric sensors (PZT), which is developed from a pertinent electromechanical impedance (EMI) theoretical model for surface-bonded circular PZT. The proposed DCMI methodology has the advantages of simple calculation and magnifying the signatures when compared with the existing methods. Combining the extracted DCMI signatures with the root mean square deviation (RMSD) index is able to quantify the correlation between the health condition and the signatures variation more effectively. To verify the effectiveness of proposed DCMI methodology, experiments are conducted on aluminum plates and a part of fuselage in detail. The experimental results sufficiently demonstrate that the presented universal DCMI methodology possesses better sensitivity than the raw signatures when utilized for evaluating the health condition of metallic structures, including those made of metal-matrix nanomaterials.
ABSTRACT
Optical control over protein expression could provide a means to interrogate a range of biological processes. One approach has employed caged ligands of the estrogen receptor (ER) in combination with broadly used ligand-dependent Cre recombinase proteins. Existing approaches use UV or blue wavelengths, which hinders their application in tissue settings. Additionally, issues of payload diffusion can impede fine spatial control over the recombination process. Here, we detail the chemical optimization of a near-infrared (NIR) light-activated variant of the ER antagonist cyclofen. These studies resulted in modification of both the caging group and payload with lipophilic n-butyl esters. The appendage of esters to the cyanine cage improved cellular uptake and retention. The installation of a 4-piperidyl ester enabled high spatial resolution of the light-initiated Cre-mediated recombination event. These studies described chemical modifications with potential general utility for improving spatial control of intracellular caging strategies. Additionally, these efforts will enable future applications to use these molecules in complex physiological settings.