Quantitative Measurements Research Articles

Development of an Odor Evaluation Method for Citrus Unshiu Peel Using an Electronic Nose Based on the Intensity of Per Unit Length (INPULTH)

Although odor is an important indicator of herbal medicine quality, an objective odor evaluation method remains undiscovered. Quantitative measurement using previous methods is complicated as Citrus Unshiu Peel (Chimpi) emits an odor when broken. To establish odor evaluation methods for herbal medicines using chimpi as an example, we developed a reproducible method for breaking samples and an objective odor evaluation method using an electronic nose (e-nose). First, an odor-emitting device (OED) was fabricated by modifying a pill cutter, which suppressed the spread of odor components into the room air while cutting the samples. The odor was emitted from chimpi with an OED and measured using an e-nose. The cut length was then measured. The sensor intensity was positively correlated with the cut length (r=0.840-0.927) in the same sample, and the intensity per unit length (INPULTH) calculated from the sensor intensity and cut length enables the comparison of the sensor intensity among different samples. In addition, average d-limonene emission level measured by GC-MS was positively correlated with average INPULTH (r=0.999), which suggests that this OED and e-nose method enables the comparison of the sensor intensity and d-limonene emissions. INPULTH also positively correlated with other seven monoterpenes such as p-cymene, β-myrcene, β-phellandrene, α-pinene, β-pinene, γ-terpinene, and α-terpinolene (r=0.701-0.865). Therefore, monoterpene content can be evaluated by measuring the odor in the same way as d-limonene. In conclusion, we developed a simple odor intensity evaluation method optimized for chimpi to establish an odor evaluation method for herbal medicines.

Interobserver reliability and accuracy of the visual assessment of interventricular septal flattening in pulmonary hypertension.

Interventricular septal (IVS) flattening is a key echocardiographic feature of pulmonary hypertension (PH) that is associated with worse outcomes. The accuracy and interobserver reliability of visual and quantitative measures of IVS in PH patients are poorly described. This single-center, retrospective analysis included 173 PH patients. All echocardiograms were independently interpreted by two board-certified echocardiographers, and IVS flattening was judged to be present visually and by calculating the eccentricity index (EI). A receiver operating characteristics analysis was conducted to determine the EI with the highest combination of sensitivity and specificity for visual IVS flattening. The agreement between the two echocardiographers for calculation of EI was assessed using Bland-Altman analysis. The overall percent agreement for visual IVS flattening was 72% with a Kappa coefficient of 0.27. Agreement was highest for patients with pre-capillary PH and lowest for those with isolated post-capillary PH. An EI cut-off of 1.5 had the highest combination of specificity (80%) and sensitivity (32%) to distinguish visual septal flattening. Bland-Altman analysis showed wide 95% limits of agreement between echocardiographers for EI measured during systole and diastole. There was a fair degree of agreement between two echo readers for the presence or absence of IVS flattening, which differed based on the hemodynamic subgroup of PH. Compared to the quantitative measure EI, visual assessment had a moderately high specificity but very low sensitivity for the presence of IVS flattening. Automated measures of IVS flattening should be considered to improve the accuracy and reliability of this key metric.

Mouse liver blood flow is regulated by hepatic stellate cells in response to the sympathetic neurotransmitter norepinephrine

BackgroundThere is no clear information on the regulation of liver blood flow by the autonomic nervous system. We conducted this study to investigate whether quiescent hepatic stellate cells (qHSCs) regulate liver blood flow in response to the sympathetic neurotransmitter norepinephrine (NE). MethodsqHSCs isolated from mice were cultured in Dulbecco's modified Eagle medium without fetal bovine serum for 1 day on collagen gel. NE-induced qHSC contraction was evaluated using the quantitative single-cell contraction measurement method that we had developed previously. For the measurement of liver perfusion pressure in situ, a buffer solution was perfused from the portal vein in mice. ResultsNE-induced a reversible contraction of qHSCs. This contraction was suppressed by the nonmuscle myosin II inhibitor blebbistatin, the myosin light chain kinase inhibitor ML-9, the Rho kinase inhibitor H-1152, the calmodulin inhibitor W-7, the store-operated calcium channel inhibitor YM-58483, and the IP3 receptor inhibitor xestospongin C. In contrast, the transient receptor potential C channel inhibitor SKF96365 did not affect the NE-induced contraction. ConclusionThese results suggest that qHSCs contract in response to NE. New & noteworthyThe present study provides direct evidence for the first time that norepinephrine (NE) induces a reversible contraction of isolated single quiescent hepatic stellate cells (qHSCs) and further suggests that the NE-mediated qHSC contraction participates in the regulation of liver blood flow in vivo.

Health-related quality of life in children with presumptive TB.

Respiratory illnesses, including pulmonary TB (PTB), cause significant morbidity. We aimed to understand the health-related quality of life (HRQoL) of children with presumptive PTB. Children aged 0-13 years presenting with presumptive PTB were enrolled. This study includes children who started TB treatment and children in whom TB was excluded (symptomatic controls). Quantitative data were collected using the Toddler and Infant quality of life Instrument (TANDI) (<3 years) and European Quality of Life-5 Dimensions-Youth (EQ-5D-Y) (>3 years) measures. Qualitative data were collected through in-depth interviews using thematic analysis. Quantitative data from caregivers of 201 children (TANDI: n = 170; EQ-5D-Y: n = 31) showed 77 (38.3%) were diagnosed with TB, while 124 (61.7%) were symptomatic controls. Qualitative data from 15 caregivers of 21 children included 10 (67%) children with TB and 5 (33%) symptomatic controls. The median TANDI Visual Analogue Score (VAS) for overall health was 90% (IQR 80-100); the EQ-5D-Y VAS median was 95% (IQR 80-100). Caregivers described decreased energy, difficulty eating, and increased sleep using qualitative interviews, which were not reflected in the quantitative data. No differences were found between children with TB and symptomatic controls. HRQoL was high in children with TB, but discrepancies between quantitative and qualitative measures highlight the limitations of the current HRQoL measures.

Do measures of central sensitization relate to movement-evoked pain in people with chronic low back pain? A longitudinal prospective study

BackgroundOne of the most frequent complaints among people with musculoskeletal pain is pain during physical activity, commonly referred to as movement-evoked pain. It is suggested to be associated with quantitative sensory testing measures of central pain process in individuals with musculoskeletal pain. ObjectiveTo investigate the predictive association between movement-evoked pain scores and measures of central sensitization in patients with chronic nonspecific low back pain. The secondary aim was to determine whether changes in movement-evoked pain scores are associated with changes in measures of central sensitization. MethodsIn this longitudinal prospective study, 50 participants with chronic low back pain were included. Pain pressure thresholds, temporal summation of pain, descending pain modulation, and the central sensitization index were assessed as measures of central sensitization. Movement-evoked pain was evaluated using the Back Performance Scale and a 5-minute walk test. ResultsMeasures of central sensitization, specifically pressure pain thresholds and temporal summation, demonstrated predictive associations with movement-evoked pain measures. In response to treatment, improvements in movement-evoked pain were associated with improvements in measures of central sensitization (i.e., pressure pain thresholds and temporal summation) and improved pressure pain thresholds in the plantar toe significantly predict movement-evoked pain measures experienced during the 5-minute walk test. ConclusionsThese results imply that movement-evoked pain is related to processes related to central modulation of pain in patients with nonspecific chronic low back pain.

Quantitative assessment and dynamic characteristic measurement of regional resilience: from the perspective of post-earthquakes effects

Strong geological disasters have caused persistent losses in society, economy, and ecological environments. Given the unique geographical settings of the stricken areas, their resilience is prone to damage or even loss. Comprehensive risk assessment of natural disasters is the core content and important foundation for building regional resilience. Therefore, conducting dynamic characteristics analysis of resilience in mountainous disaster areas impacted by strong earthquake geological disasters is vital for ensuring the region's high-quality and sustainable development. This article takes the 51 stricken areas of Wenchuan earthquake as the research object. To this end, social, economic and ecological environmental data from 2008 to 2020 was hereby collected. Initially, a regional resilience assessment system based on "socio-economic-ecological environment" was established, considering the long-term and spatial heterogeneity of geological disasters. Secondly, the regional resilience assessment model was constructed using Spectral clustering-genetic algorithm-improved entropy weight method. Following that, the dynamic characteristics of regional resilience were quantitatively analyzed from two aspects, including change velocity state and change rate trend. Finally, based on the regional resilience characteristics, differentiated resilience enhancement strategies were proposed. Collectively, the results revealed that: (1) From a geological disaster standpoint, the risk in post-earthquake disaster areas exhibited a strikingly rapid decline, with the spatial distribution of geological disaster risk being notably higher in the central areas and diminishing towards the peripheries. (2) Overall, the regional resilience of the 51 stricken areas showed a "V-shaped" trend, with a significant upturn since 2012. (3) From the perspective of dynamic characteristics, more counties (cities) presented an upward trend. (4) The 51 stricken areas were hereby divided into the "benchmarking type", the "declination type", the "backward type", and the "potential type". In conclusion, the current study enhances the technical framework for evaluating regional resilience and provides technical support for the construction of resilient cities.

Development and Validation of the Placenta-QUS Model for the Detection of Placenta-mediated Diseases using Quantitative Ultrasound Measurements: An Ex Vivo Proof-of-concept Study

IntroductionPlacenta-mediated diseases are associated with structural changes in the placenta. Quantitative Ultrasound (QUS) imaging measures the acoustic properties of the tissue, which are correlated to the underlying tissue structure. We aimed to develop and validate a diagnostic prediction model using QUS measurements for pre-eclampsia (PE) and small-for-gestational-age (SGA) fetuses/neonates. MethodsFor this prospective case-control study, placentas were collected from a group of women who delivered via cesarean section at BC Women's Hospital, Vancouver, Canada. Ultrasound data were collected and processed to compute three QUS parameters, namely, attenuation coefficient estimate (ACE), integrated backscatter coefficient (IBC), and effective scatterer diameter (ESD) from the placentas. We developed a logistic regression model using QUS parameters as predictors. The primary outcome was the occurrence of SGA and PE. ResultsThe dataset consisted of 47 placentas, of which 25 placentas were complicated by SGA/PE. The final placenta-QUS model included quadratic and interaction terms of ACE, IBC, and ESD parameters. The placenta-QUS model was well-calibrated, with a calibration slope of 0.99 (0.57 – 1.05) and a calibration intercept of 0.003 (-0.02 − 0.22). The model predicted the SGA/PE complicated pregnancies with an apparent Area Under the Receive Operating Characteristic Curve (AUROC) of 0.89 (95% CI: 0.78-0.98). The optimism-adjusted AUROC was 0.88 (95% CI: 0.78-0.98). DiscussionA model for SGA and PE has been developed using QUS measures from the placenta ex vivo. The model showed promising performance in detecting SGA/PE. Future studies will be performed to assess the model performance using QUS measures in utero.

Local goal-based governance: a novel approach to environmental sustainability in China?

Abstract The recent emergence of goal-based governance at global scale may be considered as a new approach to enhance environmental sustainability at local level. This article examines how local goal-based governance actually unfolds with a focus on its fundamental features and effectiveness. We build a conceptual framework for local goal-based governance which consists of three key elements: nature of problem, setting the goals, and achieving the goals. It provides a set of theoretical propositions: 1) the problems with two defining features are more amendable to goal-setting strategies, 2) setting a specified, practical, and learning-focused goal structure as the key premise, 3) goal attainment is built around a campaign-mode experimentation to try and find out locally appropriate approaches, a double-layered engagement between civil society and statutory institutions, and a system to track the goals through quantitative and qualitative measures. Based on semi-structured interviews and documents analysis, we adopt a case study of Chinese local waste management to test the theory and explain the unique process of local goal-based governance. This article also discusses how local goal-based governance differs from the traditional rule-based governance and further explores how these two governance strategies interact with each other to realize local changes. We highlight two complementary effects: enabling and compensating. Local goal-based governance has unique strengths to compensate for the weakness of rule-based system in promoting civic engagement; and meanwhile rule-based governance creates favorable social conditions within which local goal-based governance is initiated and developed. The inherent limitations of local goal-based governance are also discussed.

Retrolabyrinthine approach to the lateral skull base: The value of preoperative temporal bone CT analysis

PurposeThe most used neurosurgical approach to reach cerebellar-pontine angle is the retrosigmoid route. This article describes the presigmoid approach which requires excellent knowledge of the labyrinthine block together with quantitative analysis of temporal bone CT. MethodsCT-based quantitative measurements were obtained in patients undergoing vestibular neurectomy with a presigmoid approach. Eighteen patients were enrolled, and five measures were taken: Trautmann’s area, the petro-clival angle, presigmoid dura length and its angle. The relationship between these measurements and hospitalization days, operating times, and complications was explored. ResultsThe posterior semicircilar canal (PSC)-sigmoid sinus (SS) distance, presigmoid dura- internal auditory canal (IAC)-PSC angle, and duration of surgery are predictors of complications. Specifically, a PSC-sigmoid sinus distance <11 mm, a dura presig-IAC-PSC angle <14 are associated with the highest risk of complications. ConclusionPreoperative temporal bone CT scan can guide the surgeon through the narrowest areas of the surgical approach. Trautmann’s triangle area and petro-clival angle reduction are challenging and can be faced with combined microscopic-endoscopic technique, and with optics angulation-rotation. The retrolabyrinthine approach can enable hearing preservation and minimal cerebellar retraction.

Purification, fibrinolytic activity and substrate binding of nattokinase from Bacillus subtilis: A rapid and sensitive detection for fibrinolytic activity of nattokinase

Nattokinase (NK, EC 3.4.21.62) is an alkaline serine protease secreted by B. subtilis, which has a strong fibrinolytic activity in vitro and in vivo. Here, we fermented NK using a B. subtilis strain and purified the protein, designed a peptide segment derived from fibrin as a substrate of NK. Based on fluorescence resonance energy transfer (FRET), we found that NK exhibits a high hydrolytic activity towards the peptide, with Km of 9.33 ± 1.28 μM, kcat of 0.20 ± 0.01 s−1, and kcat/Km of 21,436.23 s−1 M−1, demonstrating that the peptide is a substrate for NK. Furthermore, we investigated the binding of the substrate with NK by tryptophan fluorescence quenching, molecular docking and dynamics simulation. Fluorescence quenching showed that the substrate binds to NK mainly through hydrogen bonding and van der Waals forces, with dissociation constants KD of 13.73 and 21.24 μM at 25 and 35 °C, respectively. Molecular docking and dynamics analysis revealed that the substrate recognizes the active site of NK, and provides new information on the characteristics of the binding of the substrate with NK. Our study demonstrated a rapid and sensitive method for the quantitative measurement of fibrinolytic activity of NK based on the substrate, which is very reproducible and rapid with virtually complete results in approximately 20 min.

Quantitative measures of recent and lifetime agricultural pesticide use are associated with increased pesticide concentrations in house dust

ObjectiveElevated pesticide concentrations have been found in dust from homes with residents who use agricultural pesticides, but few studies have compared these concentrations to quantitative measures of their use. We evaluated household pesticide dust concentrations in relation to quantitative, active ingredient-specific metrics of agricultural pesticide use in the Biomarkers of Exposure and Effect in Agriculture Study. MethodsParticipants provided vacuum dust samples (2013–2018) and information regarding recent (last 12 months) and lifetime pesticide use. Thirty-two pesticide analytes were measured in 295 dust samples from 213 participants; 54 had repeated measurements (median = 96 days between visits). We used mixed-effects quantile regression models to estimate relative differences in pesticide concentrations for recent and lifetime agricultural use (number of days, intensity-weighted days), recent home/garden use (yes/no), and household characteristics. Only household characteristics were examined for dacthal because of no use information. We calculated intraclass correlation coefficients (ICCs) to evaluate temporal variability. We report only descriptive statistics for pesticides with detection rates <25 %. ResultsFor currently used pesticides, quantitative measures of recent agricultural use were associated with significantly increased household pesticide dust concentrations for malathion, metolachlor, acetochlor, cyfluthrin, and atrazine (p-trends < 0.001), but not permethrin. Similarly, quantitative measures of lifetime use were associated with increased concentrations of malathion, metolachlor, carbaryl, diazinon, and atrazine (p-trends < 0.001), but not permethrin, chlorpyrifos, or chlorothalonil. For banned pesticides, ever agricultural use was associated with elevated chlordane and heptachlor concentrations and non-significantly elevated dieldrin concentrations, but not lindane, p,p-DDD, p,p-DDE, or p,p-DDT. Recent home/garden use predicted increased malathion, carbaryl, and cyfluthrin concentrations. ICCs (range = 0.57–0.90) suggested moderate to high correlation over 3–6 months. Detection rates were <25 % for alachlor, butylate, EPTC, metribuzin, simazine, carbofuran, coumaphos, as well as for three banned pesticides (cyanazine, aldrin, endosulfan). ConclusionsHousehold pesticide dust concentrations were strongly associated with the frequency of agricultural pesticide use.

Acorus tatarinowii alleviates D-galactose-induced Alzheimer’s-like disease cognitive impairment and Aβ-induced pericytes dysfunction in mice

Pericytes regulate cerebral blood flow (CBF) and excess amyloid in the brain. Pericyte dysfunction may contribute to the pathology of Alzheimer’s disease (AD). Acorus tatarinowii (AT), a Chinese medicine commonly used to treat AD, protects the central nervous system. However, whether AT can regulate pericyte function and ameliorate cognitive dysfunction remains unclear. We employed a novel target recognition assay, quantitative measurement of CBF, hematoxylin and eosin staining, immunofluorescence staining, and Western blot to investigate the role of AT in improving cognitive function in patients with AD. Additionally, we investigated the therapeutic potential of β-Asarone, the primary active compound in AT, for treating AD by modulating pericyte function using transmission electron microscopy, silver staining, electrical impedance, and other methodologies. The results revealed that administration of AT effectively alleviated the cognitive impairments induced by D-galactose in mice, as evidenced by enhanced CBF, improved histological characteristics of damaged brain tissue cells, increased expression of platelet-derived growth factor-β (PDGF-β), decreased Aβ accumulation via enhanced lipoprotein receptor-related protein 1 (LRP1), and reduced beta-site APP-cleaving enzyme 1 (BACE1). β-Asarone treatment mitigated ROS release and BACE1 expression while elevating the cell index in Aβ1-40 injured mouse brain vascular pericytes (MBVP). These findings suggest that AT has the potential to enhance CBF and mitigate pericellular dysfunction, thereby ameliorating Aβ deposition in the brain and improving cognitive impairment in patients with AD

An Adverse Outcome Pathway Approach Linking Retinoid Signaling Disruption to Teratogenicity and Population-Level Outcomes

Recent research efforts in endocrine disruption have focused on evaluating non-EATS (estrogen, androgen, thyroid, and steroidogenesis) pathways. Retinoid signaling disruption is noteworthy because of its teratogenic effects and environmental relevance. However, current environmental risk assessments are limited in their ability to evaluate impacts on individuals and populations. This study characterizes an Adverse Outcome Pathway (AOP) network linking retinoid signaling disruption to teratogenicity and survival in zebrafish. We identified Retinoic Acid Receptor (RAR) overactivation as the molecular initiating event leading to key events including craniofacial (CFM) and tail (TM) malformations, posterior swim bladder (SB) non-inflation, impaired swimming performance, and reduced feeding, ultimately resulting in decreased survival. Our study (1) determines critical sensitivity windows for CFM, posterior SB non-inflation, and TM, (2) provides quantitative measurements for CFM and TM, and (3) defines impacts on higher biological levels including food ingestion, swimming, and survival. Results show that all-trans retinoic acid (ATRA) induces strong teratogenic effects with sensitivity windows between 4-48 hours post fertilization (hpf) for CFM, TM, and posterior SB non-inflation. TM is the most sensitive indicator, with EC50 of 0.2 - 0.26 µg/L across exposure windows 4-48, 4-72, 4-96, and 4-120 hpf. Besides inducing known malformations, ATRA impaired posterior SB inflation with EC50 of 1 - 1.21 µg/L across the same exposure windows. ATRA exposure (1 µg/L) resulted in 50% food ingestion inhibition at 7 days post fertilization (dpf) and 10% survival at 14 dpf. This study provides a regulatory-relevant framework linking developmental effects to population outcomes, highlighting ecological risks and needs for improved risk assessments.

Efficacy of Melia azedarach leaf extract in different solvents against Heterotermes indicola Wasmann (Blattodea: Rhinotermitidae) using non-durable wooden blocks under laboratory and field conditions

Hetertermes indicola Wasman (Blattodea: Rhinotermitidae) is a highly wood-destructive termite species in the urban settings of Pakistan. This study evaluated the biocidal action of Melia azedarach leaf extract in different solvents on H. indicola by conducting choice and no-choice feeding deterrence assays using impregnated palatable wood under field and laboratory conditions. Dose-dependent and time-dependent trends were observed in the leaf extracts of M. azedarach at different concentrations (500, 1000, and 1500 ppm) using solvent water and methanol with 80–100 % termite mortality after 6 days of exposure. A key outcome was the higher termiticidal efficacy of methanolic extract compared to aqueous extract under both field and laboratory conditions. The LC50 values of 358 ppm for methanol and 466 ppm for aqueous extract after 15 days in a laboratory no-choice experiment exhibit a quantitative measure of chinaberry leaf extract toxicity. A significant reduction in mean percent weight loss (8.26 %) of treated wood with 1500 ppm of M. azedarach leaf extract in methanol was observed under field conditions. In conclusion, triterpenoids and phytol present in methanolic leaf extract demonstrated higher efficacy in both lab and field conditions making a solid foundation for the further development of natural wood preservatives. Since they induced rapid lethargic conditions in termites and digestive toxicity which leads to minimum loss of treated wood.

The principle of justice in the construction of a special legal status (historical and theoretical aspect)

The subject of the study is the principle of justice. The idea of justice is revealed in the context of the legal regulation of the rights and obligations of persons with special legal status. The essential aspects of the principle of equity at the individual and regulatory level are analyzed. It is noted that the principle of justice in relation to special legal status means the following: 1) any specific rights and obligations included in it must be established on certain grounds; 2) the content of these rights and obligations must correspond to the nature of these grounds. Thus, violations of justice in the construction of a special legal status can be of two kinds: either arbitrary (groundless) granting of rights or assignment of duties, or, if there are such grounds, excessive or insufficient nature of rights and duties. The research methodology includes the following approaches: comparative analysis, abstraction, deduction, induction, idealization, formalization, axiomatic and logical method. It seems important to distinguish between the aspects of justice: qualitative and quantitative. The qualitative characteristic of justice is to ensure that the grounds of a special legal status, on the one hand, and its content, on the other, are homogeneous in their value nature; for example, that an act of positive social significance (merit) generates a positive legal assessment expressed in the provision of additional benefits (encouragement), and vice versa. The quantitative measurement of justice assumes that the volume of social benefits or encumbrances inherent in a special legal status reflected, at least with some degree of accuracy, the similar significance of what served as the basis for this. From a practical point of view, the fairness of a special legal status can be revealed at two levels: individual (law enforcement) or normative (law-making).

Economic assessment of animal disease burden in Senegalese small ruminants

Small ruminant production in sub-Saharan Africa is limited by a range of constraints, including animal health issues. This study aimed at estimating the impact of these issues on the small ruminant production in Senegal in a holistic manner, using an approach developed by the Global Burden of Animal Diseases (GBADs) programme. The estimation focused on the mixed crop-livestock system, representing a large proportion (>60%) of the small ruminant population in the country. It was based on existing data collected via a systematic literature review, acquisition of secondary datasets from local stakeholders, and expert elicitation. A dynamic population model was used to calculate the gross margin of the sector under both the current health constraints and an ideal health state, where animals are not exposed to causes of morbidity and mortality. The difference between the current and ideal health scenarios, termed the Animal Health Loss Envelope (AHLE), provides a quantitative measure of the farm-level cost of disease in the system. The all-cause AHLE was estimated at 292 billion FCFA (468 million USD, with 95% prediction interval 216 – 366 billion FCFA) per year for 2022, for a population of 8.8 million animals. The contribution of Peste des Petits Ruminants (PPR) was modelled separately, as an example of attributing part of the AHLE to a specific disease cause. PPR was estimated to contribute 5% of the total AHLE. The animal disease burden experienced by Senegalese livestock keepers was largely due to loss in animals and production, with relatively small amounts of animal health expenditure. Implementation of this study contributed to the further development of the GBADs approach. Such estimates can support decision making at all levels, from investment decisions at the international level to local disease awareness campaigns targeting livestock keepers.

Selective Conversion of CO2 to CO Using Blue TiO2 with an r-GO Shell and Quantitative Measurement of Excited Electrons with Four-Wave Mixing Microspectroscopy

Selective Conversion of CO2 to CO Using Blue TiO2 with an r-GO Shell and Quantitative Measurement of Excited Electrons with Four-Wave Mixing Microspectroscopy

Toward quantitative thermoelectric characterization of (nano)materials by in-situ transmission electron microscopy

We explore the possibility to perform an in-situ transmission electron microscopy (TEM) thermoelectric characterization of materials. A differential heating element on a custom in-situ TEM microchip allows to generate a temperature gradient across the studied materials, which are simultaneously measured electrically. A thermovoltage was induced in all studied devices, whose sign corresponds to the sign of the Seebeck coefficient of the tested materials. The results indicate that in-situ thermoelectric TEM studies can help to profoundly understand fundamental aspects of thermoelectricity, which is exemplary demonstrated by tracking the thermovoltage during in-situ crystallization of an amorphous Ge thin film. We propose an improved in-situ TEM microchip design, which should facilitate a full quantitative measurement of the induced temperature gradient, the electrical and thermal conductivities, as well as the Seebeck coefficient. The benefit of the in-situ approach is the possibility to directly correlate the thermoelectric properties with the structure and chemical composition of the entire studied device down to the atomic level, including grain boundaries, dopants or crystal defects, and to trace its dynamic evolution upon heating or during the application of electrical currents.

Detecting damage in composites using volume decomposition analysis of tomographic data

Detection of damage in a single tow ceramic matrix composite specimen has been achieved using orthogonal decomposition of volumetric tomographic datasets collected at four tensile loads. This decomposition approach has been applied at two different length scales: (i) individual fibres and (ii) bulk volumes containing fibres and matrix material. Volumes were first decomposed to feature vectors, orders of magnitude smaller than the original volume they describe, and then comparisons between datasets at different load levels were made in feature vector space. The results show quantitative measurements of damage location, damage morphology and the relative growth of this damage with increased load when compared with a dataset with less or no damage. No prior knowledge of the dataset or training of algorithms is required for damage to be detected, it is only necessary that at least two datasets are available for comparison, e.g. from in situ or repeated scanning measurements. Results are generated on significantly shorter timescales when compared with previous automated approaches to tomography data processing. This approach has the potential to be applied to damage detection in a range of materials through comparisons of volumetric datasets from a range of measurement or computational techniques.

Label-free classification of atherosclerosis plaque via OCT and ultraviolet autofluorescence spectroscopy

We proposed a label-free method for the identification and classification of atherosclerosis plaques by combining optical coherence tomography (OCT) with ultraviolet autofluorescence spectroscopy (uFLS). By aligning the OCT source and the FLS excitation beams, we were able to illuminate the same spot on plaques fixed to the integrated probe, which underwent rotational scanning. This setup enabled the detection of both OCT images and uFLS spectra of the plaques in a co-localized manner. In our approach, a 1300 nm centered swept laser source was utilized for OCT imaging, while a 355 nm laser source, along with a lensed multimode fiber, served as the fluorescence probe for uFLS. The successful acquisition of OCT-uFLS images provided complementary information regarding the tomographic internal structure and biochemical components within the vessels, allowing for comprehensive identification and classification of atherosclerosis plaques. Furthermore, we achieved quantitative measurements and analysis of fluorescence spectra from three main component channels, corresponding to collagen, elastin, and lipid. This enabled us to differentiate atherosclerosis from normal vessel walls and determine the specific types. With the implementation of this dual-modal OCT-uFLS technique, it is possible to facilitate the label-free classification of various histopathological types of atherosclerosis plaques, which holds the potential for both diagnosis and image-guided ablation therapy applications.