Different tabletop sugar and zero to low‐calorie sweetener samples (sachets) of different suppliers, taken randomly, at different cafeterias in Brazil, Argentina, and Paraguay have been selected, for ...spectroscopy and X‐ray diffraction analysis, to figure out if they can present non‐friendly components in their composition. Traces of sulfites and aluminosilicates make only 2 out of 16 tabletop sugar sweetener samples safe. On the other hand, traces of sucrose, lactose, sulfites, and aspartame, make only 1 out of 13 tabletop zero to low‐calorie sweetener samples, safe.
Aim
To establish a method using Fourier Transform Infra‐Red spectroscopy (FTIR) to characterize the nature and depth of changes in dentinal collagen following exposure to sodium hypochlorite (NaOCl) ...during root canal irrigation in an ex vivo model.
Methodology
Fourier Transform Infra‐Red spectroscopy was used to assess the changes in dentinal collagen when the root canal was exposed to NaOCl. The changes in dentinal collagen caused by NaOCl irrigation of root canals in transverse sections of roots, at 0.5 mm from the canal wall and 0.5 mm from the external root surface, were assessed by FTIR. The data were analysed using paired t‐test with 5% significance level.
Results
Fourier Transform Infra‐Red spectroscopy confirmed that NaOCl exposure caused alterations in the chemistry and structure of collagen in dentine. FTIR spectra obtained from dentine surfaces and dentine adjacent to root canals exposed to NaOCl, all consistently showed degradation and conformational change of the collagen structure. FTIR data from the ex vivo model showed that the depth of effect of NaOCl extended to at least 0.5 mm from the canal wall.
Conclusion
In extracted human teeth, NaOCl caused changes in dentinal collagen that were measurable by FTIR. In an ex vivo model, the depth of effect into dentine extended at least 0.5 mm from the canal wall.
Thermal transport in polymer nanocomposites becomes dependent on the interfacial thermal conductance due to the ultra‐high density of the internal interfaces when the polymer and filler domains are ...intimately mixed at the nanoscale. However, there is a lack of experimental measurements that can link the thermal conductance across the interfaces to the chemistry and bonding between the polymer molecules and the glass surface. Characterizing the thermal properties of amorphous composites are a particular challenge as their low intrinsic thermal conductivity leads to poor measurement sensitivity of the interfacial thermal conductance. To address this issue here, polymers are confined in porous organosilicates with high interfacial densities, stable composite structure, and varying surface chemistries. The thermal conductivities and fracture energies of the composites are measured with frequency dependent time‐domain thermoreflectance (TDTR) and thin‐film fracture testing, respectively. Effective medium theory (EMT) along with finite element analysis (FEA) is then used to uniquely extract the thermal boundary conductance (TBC) from the measured thermal conductivity of the composites. Changes in TBC are then linked to the hydrogen bonding between the polymer and organosilicate as quantified by Fourier‐transform infrared (FTIR) and X‐ray photoelectron (XPS) spectroscopy. This platform for analysis is a new paradigm in the experimental investigation of heat flow across constituent domains.
We conducted TDTR on films with polymer confined in nanoporous organosilicates with high interfacial densities and varying surface chemistries. EMT along withFEA was used to extract the TBC and linked to spectroscopy quantifying hydrogen bonding between the polymer and organosilicate. This result establishes an approach to link interfacial conductance and chemical bonding.
Condom (specifically silicone) lubricants are a form of trace evidence being increasingly submitted for examination in forensic investigations of sexual assault. Interpreting these traces requires an ...understanding of their transfer and persistence, such as being able to quantify the amount of transferred material as well as the loss percentage over time. However, to the best of our knowledge, an accurate quantification method for silicone polymers within a forensic context has not been reported. This study evaluated diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), a commonly used method for qualitative analysis of condom evidence in casework, as an approach for the quantification or semi-quantification of silicone lubricants in solution. Although a general trend was observed between the DRIFTS signal and the silicone lubricant concentration, high variability between sample runs meant that these changes were not reproducible enough for quantitative prediction.
Cerebral hypoperfusion is implicated in the pathogenesis of associations between orthostatic hypotension and adverse outcome such as falls, cognitive impairment, depression, and mortality. Although ...the blood pressure response to orthostasis has been well studied there is a lack of information on orthostatic cerebrovascular responses in older populations.
We measured cerebral hemodynamics, utilizing near infrared spectroscopy, coupled with peripheral blood pressure during an active stand in a large population of well-phenotyped older adults (N = 2764). Multi-level mixed effect models were utilized to investigate associations with age and sex, as well as confounders including anti-hypertensive medications. Normative cerebral oxygenation responses were also modelled utilizing generalized additive models for location, scale, and shape (GAMLSS). Older age groups experienced larger initial drops in oxygenation and a slower recovery, and responses also differed by sex. The drop after standing ranged from −1.85 % (95 % confidence interval (CI): −2.02 to −1.68) in the males aged 54–59 years vs −1.15 % (95 % CI: −1.31 to −1.00) in females aged 54–59 years, to −2.67 % (95 % CI: −3.01 to −2.33) in males aged ≥ 80 years vs −1.97 % (95 % CI: −2.32 to −1.62) females aged ≥ 80 years. Reduced oxygenation levels were also evident in those taking anti-hypertensive medications.
Cerebral autoregulation is impaired with age, particularly in older women and those taking anti-hypertensives. SBP during the stand explained some of the age gradient in the late recovery stage of the stand for the oldest age group. Reported orthostatic symptoms did not correlate with hypoperfusion. Therefore, measures of orthostatic cerebral flow should be assessed in addition to peripheral BP in older patients irrespective of symptoms. Further studies are required to investigate the relationship between NIRS measurements and clinical outcomes such as falls, cognitive impairment and depression.
•We profiled the cerebral oxygenation response to orthostasis in large well-described community-dwelling population, adjusting for a large number of confounders.•Older age groups had a larger initial drop in cerebral oxygenation and impaired stabilization.•Women experienced a smaller drop in oxygenation compared to men, but impaired stabilization was more marked in women.•Those treated with anti-hypertensive medications had deficits in recovery of cerebral oxygenation after standing.•Hypoperfusion did not correlate with reported orthostatic symptoms.
This study investigates the hypothesis that thermal adaptive opportunities available to building occupants affect their cognitive performance and mental workload. The change rate of cerebral blood ...flow (Δtotal Hb) was measured by Near Infra-Red Spectroscopy (NIRS) and interpreted as the metric of mental workload in subjects while performing cognitive tasks (n-back tests) with, or without access to thermal adaptive opportunities such as regulable fan-induced air flow and clothing insulation adjustment. Participants underwent three experimental conditions: Condition 22 (operative temperature to = 22 °C without adaptive opportunities), Condition 28 (to = 28 °C without adaptive opportunities), and Condition 28w (to = 28 °C with adaptive opportunities. Under Condition 28w, thermal sensations were neutral, while thermal satisfaction and comfort levels were higher than those reported for Condition 28, and the same as those reported under Condition 22. The subjects' mean skin temperature under Condition 22 was the lowest at 32.1 °C, followed by Condition 28w at 33.6 °C, while the highest, 34.5 °C was recorded in Condition 28. No significant differences were observed in accuracy and reaction time of n-back tests between the three different environmental conditions. Under Condition 28w, mental fatigue levels and the left side Δ total Hb results were lowest out of all three conditions, although the differences failed to reach statistical significance. Availability of adaptive opportunities plays a role in expanding the range of thermal environmental conditions for optimal cognitive task performance in a moderately warm environment (to = 28 °C). This finding cannot be fully explained by the direct effect of adaptive behaviours on human heat balance and associated physiological responses, but the unexplained component may potentially be attributed to the psychological dimension of human adaptive response. These findings and their interpretation within an adaptive comfort framework are consistent with the extended-U hypothesis of cognitive performance.
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•Thermal adaptive opportunities reduced thermal discomfort, mental fatigue and workload.•There were no significant differences in performance of n-back tests between 22 and 28 °C.•Thermal adaptive opportunities at 28 °C has a potential for reducing building energy demand.
The aim of this study was to locate the breakpoints of cerebral and muscle oxygenation and muscle electrical activity during a ramp exercise in reference to the first and second ventilatory ...thresholds. Twenty-five cyclists completed a maximal ramp test on an electromagnetically braked cycle-ergometer with a rate of increment of 25 W/min. Expired gazes (breath-by-breath), prefrontal cortex and vastus lateralis (VL) oxygenation Near-infrared spectroscopy (NIRS) together with electromyographic (EMG) Root Mean Square (RMS) activity for the VL, rectus femoris (RF), and biceps femoris (BF) muscles were continuously assessed. There was a non-linear increase in both cerebral deoxyhemoglobin (at 56 ± 13% of the exercise) and oxyhemoglobin (56 ± 8% of exercise) concomitantly to the first ventilatory threshold (57 ± 6% of exercise, p > 0.86, Cohen's d < 0.1). Cerebral deoxyhemoglobin further increased (87 ± 10% of exercise) while oxyhemoglobin reached a plateau/decreased (86 ± 8% of exercise) after the second ventilatory threshold (81 ± 6% of exercise, p < 0.05, d > 0.8). We identified one threshold only for muscle parameters with a non-linear decrease in muscle oxyhemoglobin (78 ± 9% of exercise), attenuation in muscle deoxyhemoglobin (80 ± 8% of exercise), and increase in EMG activity of VL (89 ± 5% of exercise), RF (82 ± 14% of exercise), and BF (85 ± 9% of exercise). The thresholds in BF and VL EMG activity occurred after the second ventilatory threshold (p < 0.05, d > 0.6). Our results suggest that the metabolic and ventilatory events characterizing this latter cardiopulmonary threshold may affect both cerebral and muscle oxygenation levels, and in turn, muscle recruitment responses.
Reports suggest that adults with post-COVID-19 syndrome or long COVID may be affected by orthostatic intolerance syndromes, with autonomic nervous system dysfunction as a possible causal factor of ...neurocardiovascular instability (NCVI). Long COVID can also manifest as prolonged fatigue, which may be linked to neuromuscular function impairment (NMFI). The current clinical assessment for NCVI monitors neurocardiovascular performance upon the application of orthostatic stressors such as an active (i.e., self-induced) stand or a passive (tilt table) standing test. Lower limb muscle contractions may be important in orthostatic recovery via the skeletal muscle pump. In this study, adults with long COVID were assessed with a protocol that, in addition to the standard NCVI tests, incorporated simultaneous lower limb muscle monitoring for NMFI assessment.
To conduct such an investigation, a wide range of continuous non-invasive biomedical sensing technologies were employed, including digital artery photoplethysmography for the extraction of cardiovascular signals, near-infrared spectroscopy for the extraction of regional tissue oxygenation in brain and muscle, and electromyography for assessment of timed muscle contractions in the lower limbs.
With the proposed methodology described and exemplified in this paper, we were able to collect relevant physiological data for the assessment of neurocardiovascular and neuromuscular functioning. We were also able to integrate signals from a variety of instruments in a synchronized fashion and visualize the interactions between different physiological signals during the combined NCVI/NMFI assessment. Multiple counts of evidence were collected, which can capture the dynamics between skeletal muscle contractions and neurocardiovascular responses.
The proposed methodology can offer an overview of the functioning of the neurocardiovascular and neuromuscular systems in a combined NCVI/NMFI setup and is capable of conducting comparative studies with signals from multiple participants at any given time in the assessment. This could help clinicians and researchers generate and test hypotheses based on the multimodal inspection of raw data in long COVID and other cohorts.
In this work, the feasibility of implementing a process analytical technology (PAT) platform consisting of Near Infrared Spectroscopy (NIR) and particle size distribution (PSD) analysis was evaluated ...for the prediction of granule downstream processability. A Design of Experiments-based calibration set was prepared using a fluid bed melt granulation process by varying the binder content, granulation time, and granulation temperature. The granule samples were characterized using PAT tools and a compaction simulator in the 100-500 kg load range. Comparing the systematic variability in NIR and PSD data, their complementarity was demonstrated by identifying joint and unique sources of variation. These particularities of the data explained some differences in the performance of individual models. Regarding the fusion of data sources, the input data structure for partial least squares (PLS) based models did not significantly impact the predictive performance, as the root mean squared error of prediction (RMSEP) values were similar. Comparing PLS and artificial neural network (ANN) models, it was observed that the ANNs systematically provided superior model performance. For example, the best tensile strength, ejection stress, and detachment stress prediction with ANN resulted in an RMSEP of 0.119, 0.256, and 0.293 as opposed to the 0.180, 0.395, and 0.430 RMSEPs of the PLS models, respectively. Finally, the robustness of the developed models was assessed.
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