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Predicting Mechanical Strength of In-Use Firefighter Protective Clothing Using Near-Infrared Spectroscopy
摘要： The exact lifespan of in-use firefighter protective clothing is difficult to predict due to the large variations in use between individual garments. Furthermore, testing methods used to evaluate new protective clothing are destructive in nature and could not be applied to in-use garments. Various non-destructive techniques have been proposed for the evaluation of in-use clothing, each possessing its own advantages and disadvantages. The ability of near-infrared spectroscopy to predict the tensile strength of thermally aged fabrics used in protective clothing for wildland firefighters and other workers is investigated here. Fabrics were exposed to heat fluxes from 10 kW/m2 to 40 kW/m2 for various durations using the cone calorimeter, after which the tensile strength of the fabrics was measured. Temperatures measured during the exposures and results of thermal gravimetric analysis tests were used to interpret changes in tensile strength. Multivariate linear regression was used to develop correlations between the tensile strength and the reflectance values measured between 1500 nm and 2500 nm for new and thermally aged fabrics. It was found that models based on reflectance measurements made at as few as three wavelengths could be used to estimate the tensile strength of the thermally aged specimens.
关键词： Thermal ageing,Near-infrared spectroscopy,Firefighter,Durability,Non-destructive testing,Protective clothing
更新于2025-09-23 15:22:29
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Multi-mode heterodyned 5th-order infrared spectroscopy
摘要： Fifth-order multidimensional infrared spectroscopy with heterodyned detection was carried out in the three-beam dual-frequency configuration. Numerous 5th-order cross peaks were detected for the 4-azidobutyrate-N-hydroxysuccinimide ester compound in solution involving several vibrational modes ranging in frequency from 1045 to 2100 cm?1. Cross peaks involving overtones (2X/Z) and combination bands (XY/Z) among the tags, modes X and Y excited by the first two mid-IR laser pulses, and the reporter, modes Z excited by the third laser pulse, were acquired and the factors affecting the amplitude of 5th-order cross peaks are discussed. The 5th-order cross peaks were detected among modes that are spatially close (a few bonds apart) as well as for modes spatially separated by ca. 12 ? (eight bonds apart). In both cases, the waiting time dependences for the 3rd and 5th order cross peaks were found to be different. In particular, the waiting time at which the cross-peak maximum is reached, the decay time, and the value of a plateau at large waiting times were all differing strongly. The differences are explained by reduced sensitivity of the 5th-order signals to modes coupled weakly to the reporter mode and different relaxation dynamics involving overtone state of the tag. The ability of the 5th-order peaks to single out the modes coupled strongly to the reporter can help identifying specific energy relaxation and transport pathways, which will be useful for understanding energy transport dynamics in molecules. The absorptive 5th-order cross peaks were constructed which report on three-point correlation functions. It is shown that in addition to the triple-frequency correlation functions, a correlation of the frequencies with the mode coupling (anharmonicity) can be naturally measured by the 5th-order spectroscopy. The current limit for detecting 5th-order signals was estimated at the level of 1 × 10?3 in reduced anharmonicity, which is determined by the corresponding two-state anharmonicity divided by the reporter mode spectral width. Given the simplicity of recording the 5th-order cross peaks in the three-beam configuration, the approach carries a potential for a broad use.
关键词： vibrational modes,anharmonicity,heterodyned detection,fifth-order,multidimensional infrared spectroscopy,energy transport
更新于2025-09-23 15:22:29
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Associations of Perioperative Renal Oximetry Via Near-Infrared Spectroscopy, Urinary Biomarkers, and Postoperative Acute Kidney Injury in Infants After Congenital Heart Surgery
摘要： Objectives: Examine the relationship between perioperative renal regional tissue oximetry, urinary biomarkers, and acute kidney injury in infants after congenital cardiac surgery with cardiopulmonary bypass. Design: Prospective, observational. Setting: Cardiac operating room and cardiac ICU. Patients: Neonates and infants without history of kidney injury or anatomic renal abnormality. Interventions: None. Measurements and Main Results: Renal regional tissue oximetry was measured intraoperatively and for 48 hours postoperatively. Urinary levels of neutrophil gelatinase-associated lipocalin and tissue inhibitor of metalloproteinases 2 together with insulin-like growth factor-binding protein 7 were measured preoperatively, 2, 12, and 24 hours postoperatively. Patients were categorized as no acute kidney injury, stage 1, or Stage 2–3 acute kidney injury using the Kidney Disease: Improving Global Outcomes criteria with 43 of 70 (61%) meeting criteria for any stage acute kidney injury. Stage 2–3 acute kidney injury patients had higher tissue inhibitor of metalloproteinases 2, insulin-like growth factor-binding protein 7 at 2 hours (0.3 vs 0.14 for stage 1 acute kidney injury and 0.05 for no acute kidney injury; p = 0.052) and 24 hours postoperatively (1.71 vs 0.27 for stage 1 acute kidney injury and 0.19 for no acute kidney injury, p = 0.027) and higher neutrophil gelatinase-associated lipocalin levels at 24 hours postoperatively (10.3 vs 3.4 for stage 1 acute kidney injury and 6.2 for no acute kidney injury, p = 0.019). Stage 2–3 acute kidney injury patients had lower mean cardiac ICU renal regional tissue oximetry (66% vs 79% for stage 1 acute kidney injury and 84% for no acute kidney injury, p = 0.038). Regression analyses showed that tissue inhibitor of metalloproteinases 2, insulin-like growth factor-binding protein 7 at 2 hours postoperatively and nadir intraoperative renal regional tissue oximetry to be independent predictors of postoperative kidney damage as measured by urinary neutrophil gelatinase-associated lipocalin. Conclusions: We observed modest differences in perioperative renal regional tissue oximetry and urinary biomarker levels compared between acute kidney injury groups classified by creatinine-dependent Kidney Disease: Improving Global Outcomes criteria, but there were significant correlations between renal regional tissue oximetry, tissue inhibitor of metalloproteinases 2, insulin-like growth factor-binding protein 7, and postoperative neutrophil gelatinase-associated lipocalin levels. Kidney injury after infant cardiac surgery may be undetectable by functional assessment (creatinine) alone, and continuous monitoring of renal regional tissue oximetry may be more sensitive to important subclinical acute kidney injury.
关键词： near-infrared spectroscopy,infant,biomarker,congenital heart surgery,cardiac intensive care unit,acute kidney injury
更新于2025-09-23 15:22:29
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[IEEE 2017 International Renewable and Sustainable Energy Conference (IRSEC) - Tangier (2017.12.4-2017.12.7)] 2017 International Renewable and Sustainable Energy Conference (IRSEC) - Mapping of the Composition of Soils Naturally Deposited on PV Modules Anywhere in Morocco
摘要： This article constitutes a preliminary phase for the performance of a national cartography of the composition of soils naturally deposited on photovoltaic modules installed in sites of different climates. To do this, a climatic zoning of Morocco according to the De Martonne index was adopted in order to select representative sites concerned with the collection of samples. For the moment, four samples have been collected in Rabat, Errachidia, Agadir and Oujda. These samples were prepared and analyzed. Several analyzes were carried out to determine the physical, chemical and mineralogical composition of these samples. The mineralogical composition was determined via X-Ray Diffraction (XRD) and X-Ray Fluorescence analysis (XF), while characterization of the physical and chemical composition was identified using Differential Scanning Calorimetry (DSC) and Spectroscopy Infrared (IR). The results show the existence of the same abundant constituents namely: Quartz, Calcite, Dolomite, Kaolinite whose percentages differ from a climate to another.
关键词： Soils,Quartz,Calcite,Differential Scanning Calorimetry (DSC),Kaolinite,Climatic zoning,Infrared spectroscopy (IR),X-Ray Diffraction,Photovoltaic modules,Dolomite,Cartography,X-Ray Fluorescence
更新于2025-09-23 15:22:29
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Low Renal Oxygen Saturation at Near-Infrared Spectroscopy on the First Day of Life Is Associated with Developing Acute Kidney Injury in Very Preterm Infants
摘要： Background: Acute kidney injury (AKI) is a frequent complication in preterm infants, and the identification of early markers of renal hypoperfusion is a chief challenge in neonatal intensive care units. Objectives: To describe the association between early markers of cardiovascular function and renal perfusion with AKI occurrence in a cohort of preterm infants < 32 weeks’ gestation. Methods: 128 infants were prospectively included from birth to discharge. During the first day of life, we assessed cardiovascular function, systemic and organ blood flow by Doppler ultrasound, and monitored cerebral and renal regional oxygen saturation (rSO2) using near-infrared spectroscopy (NIRS). These measures were analyzed in relation to developing AKI and serum creatinine (SCr) peak from day 2 to 7 of life. Results: 12 of 128 infants presented with AKI (9.4%). SCr peak was 155.3 ± 30.2 μmol/L in infants with AKI versus 82.0 ± 16.5 in non-AKI infants (p < 0.001). Among all measures of cardiovascular function and renal perfusion, low mean cerebral and renal rSO2 during the first day of life and a low resistive index at renal artery Doppler were significantly associated with developing AKI. After adjustment for possible confounding factors, low renal rSO2 on the first day of life remained associated with a high SCr peak from day 2 to 7 of life. Conclusion: Low renal rSO2 values during the first day of life correlate with developing AKI in preterm infants < 32 weeks’ gestation. NIRS monitoring of renal function during adaptation seems promising, and its very early use after birth to detect kidney hemodynamic dysfunction deserves further investigations.
关键词： Acute renal failure,Neonatal intensive care,Postnatal adaptation,Near-infrared spectroscopy,Renal function,Extremely low-birth-weight infants,Renal hemodynamics,Premature newborns,Patent ductus arteriosus
更新于2025-09-23 15:22:29
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Perspective: Prospects of non-invasive sensing of the human brain with diffuse optical imaging
摘要： Since the initial demonstration of near-infrared spectroscopy (NIRS) for noninvasive measurements of brain perfusion and metabolism in the 1970s, and its application to functional brain studies (fNIRS) in the 1990s, the field of noninvasive optical studies of the brain has been continuously growing. Technological developments, data analysis advances, and novel areas of application keep advancing the field. In this article, we provide a view of the state of the field of cerebral NIRS, starting with a brief historical introduction and a description of the information content of the NIRS signal. We argue that NIRS and fNIRS studies should always report data of both oxy- and deoxyhemoglobin concentrations in brain tissue, as they complement each other to provide more complete functional and physiological information, and may help identify different types of confounds. One significant challenge is the assessment of absolute tissue properties, be them optical or physiological, so that relative measurements account for the vast majority of NIRS and fNIRS applications. However, even relative measurements of hemodynamics or metabolic changes face the major problem of a potential contamination from extracerebral tissue layers. Accounting for extracerebral contributions to fNIRS signals is one of the most critical barriers in the field. We present some of the approaches that were proposed to tackle this challenge in the study of cerebral hemodynamics and functional connectivity. Finally, we critically compare fNIRS and functional magnetic resonance imaging by relating their measurements in terms of signal and noise, and by commenting on their complementarity.
关键词： hemodynamics,functional connectivity,functional magnetic resonance imaging,human brain,near-infrared spectroscopy,diffuse optical imaging,non-invasive sensing,functional near-infrared spectroscopy
更新于2025-09-23 15:21:21
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[ACS Symposium Series] Raman Spectroscopy in the Undergraduate Curriculum Volume 1305 || Implementation of Raman Spectroscopy in an Undergraduate Forensic Chemistry Course
摘要： Raman spectroscopy has emerged as a valuable instrumental tool to supplement spectroscopic approaches, such as infrared spectroscopy for analyzing forensic samples including drugs, fibers, textiles, soil components, inks, pigments, paints, and body fluids, both in the field and at crime laboratories. As a result, Raman spectroscopy has been incorporated into undergraduate forensic chemistry courses. Using a Rigaku Progeny X2 Raman spectrometer, students recorded Raman spectra of organic and inorganic materials including drugs, adulterants, and coordination complexes. Students searched for matches using a chemical library and assigned peaks attributable to the chemical structures using a correlation table. They observed conditions in which Raman spectroscopy recorded bands not observed with the infrared spectrometer, reflecting the complementarity of the two techniques. An advantage of Raman spectroscopy for forensic analysis compared to infrared spectroscopy is that dangerous samples can be analyzed through containers and aqueous solutions can be analyzed without interference from water.
关键词： Raman spectroscopy,undergraduate education,infrared spectroscopy,forensic chemistry,forensic samples
更新于2025-09-23 15:21:21
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Effect of substrate bias and substrate/plasma generator distance on properties of a-C:H:SiOx films synthesized by PACVD
摘要： In this paper the a-C:H:SiOx films were synthesized on silicon (100) and glass substrates by plasma-assisted chemical vapor deposition combined with pulsed bipolar substrate bias from mixtures of argon and polyphenylmethylsiloxane vapor. The process of a-C:H:SiOx films formation was investigated by controlling processing conditions such as amplitude of negative pulse of substrate bias and the distance between the substrate and plasma generator. Physico-mechanical characteristics of a-C:H:SiOx films were studied by the nanoindentation technique, atomic force microscopy, Fourier transform infrared and Raman spectroscopy. The contact angle and surface free energy were determined by the sessile drop method using couple liquids (water and glycerin). It was found that the films’ properties are interrelated with the density of the ion current on the substrate, which was measured using a guarded planar probe. The obtained results show that film prepared at the smaller substrate/plasma generator distance and optimal substrate biasing has a higher content of sp3 bonded carbon and, accordingly, has higher hardness, Young's modulus and resistance to plastic deformation. At the same time the a-C:H:SiOx films show large hydrophobicity with a contact angle for water of about 91° and small total surface free energy of about 17.9 mN/m.
关键词： a-C:H:SiOx films,PACVD,Raman Spectroscopy,Substrate bias,Fourier Transform Infrared Spectroscopy,Wettability
更新于2025-09-23 15:21:21
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Vibrational fingerprint of localized excitons in a two-dimensional metal-organic crystal
摘要： Long-lived excitons formed upon visible light absorption play an essential role in photovoltaics, photocatalysis, and even in high-density information storage. Here, we describe a self-assembled two-dimensional metal-organic crystal, composed of graphene-supported macrocycles, each hosting a single FeN4 center, where a single carbon monoxide molecule can adsorb. In this heme-like biomimetic model system, excitons are generated by visible laser light upon a spin transition associated with the layer 2D crystallinity, and are simultaneously detected via the carbon monoxide ligand stretching mode at room temperature and near-ambient pressure. The proposed mechanism is supported by the results of infrared and time-resolved pump-probe spectroscopies, and by ab initio theoretical methods, opening a path towards the handling of exciton dynamics on 2D biomimetic crystals.
关键词： FeN4 center,spin transition,ab initio theoretical methods,excitons,carbon monoxide,infrared spectroscopy,graphene,time-resolved pump-probe spectroscopy,two-dimensional metal-organic crystal
更新于2025-09-23 15:21:21
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Atomistic modeling of the infrared response of fullerenes under hydrostatic pressure
摘要： The anharmonic infrared spectrum of individual C60 and C70 fullerenes under hydrostatic pressure was theoretically computed by means of atomistic simulations. Using a tight-binding model for the fullerenes and a simple particle-based pressure-transmitting fluid, the structural and vibrational properties were determined at room temperature and up to 20 GPa. All properties generally exhibit relative variations that are linear with increasing pressure, but whose magnitude can be comparable to pure thermal effects. The bond length contraction usually agrees with existing results, and for C70 our approach manages to reproduce the occasionally negative pressure coefficient found for some low-frequency modes in experiments.
关键词： fullerenes,pressure effects,infrared spectroscopy
更新于2025-09-23 15:21:21