Simultaneous Sampling Research Articles

Effect of temperature on VOC emissions and odor from vehicle carpet

Volatile organic compounds (VOCs) released from carpets deteriorate the air quality in the confined vehicle interior. The wide range of temperatures experienced by vehicle carpets impacts VOC and odor emissions, affecting the physical and mental health of occupants. We investigated the VOC emissions and odor characteristics of vehicle carpets at 25, 40, 50, and 60 °C, respectively. An approach was developed for simultaneous objective sampling and subjective evaluation in a 1 m3 chamber with controlled temperature, humidity, and ventilation. Sensory panelists were screened and trained to evaluate the odor intensity, preference, and type. The emitted VOC types and concentrations increased with temperature; there were 4.5 times more VOC types at 60 °C than at 25 °C. The emission of aromatic compounds, heterocyclic compounds, acids, esters, and ketones significantly increased with temperature. The interaction between odorants affected odor characteristics at the four temperatures; the dominant odors were plastic-like and stinky at 25 °C, rubber- and leather-like at 40 and 50 °C, and aroma at 60 °C. Further quantitative and qualitative exploration of substances, odors, and health effects from carpet emissions at different temperatures could help improve the vehicle environment.

Enhancing On-Skin Analysis: A Microfluidic Device and Smartphone Imaging Module for Real-Time Quantitative Detection of Multianalytes in Sweat.

Wearable sweat sensors present exciting opportunities for advancing personal health monitoring and noninvasive biomarker measurements. However, existing sensors often fall short in accurate detection of low analyte volumes and concentrations and lack multimodal sensing capabilities. Herein, we present a highly portable four-channel microfluidic device capable of conducting simultaneous sweat sampling and fluorometric sensing of potential biomarkers, such as l-Tyr, l-Trp, Crt, and NH4+, specifically designed for kidney disease monitoring. Our microfluidic device seamlessly integrates with smartphones, facilitating easy data retrieval and analysis. The core of the sensing array is a novel fluorometric solid-state mechanism utilizing carbon polymer dots derived from dopamine, catechol, and o-phenylenediamine monomers embedded in gelatin hydrogels. The sensors exhibit exceptional performance, offering linear ranges of 5-275, 6-170, 4-220, and 5-170 μM, with impressively low detection limits of 1.5, 1.2, 1.3, and 1.4 μM for l-Tyr, l-Trp, Crt, and NH4+, respectively. Through meticulous optimization of operational variables, comprising the temperature, sample volume, and assay time, we achieved the best performance of the device. Furthermore, the sensors exhibited remarkable selectivity, effectively distinguishing between biologically similar species and other potential biological compounds found in sweat. Our evaluation also extended to monitoring kidney diseases in patients and healthy individuals, showcasing the device's utility in world scenarios. Promising results showcase the potential of low-cost, multidiagnostic microfluidic sensor arrays, especially with synthetic skin integration, for enhanced disease detection and healthcare outcomes.

New insights into the long-term dynamics and deposition-suspension distribution of atmospheric microplastics in an urban area

Atmospheric microplastics (AMPs) transmitted through the atmosphere are critical to global microplastic pollution. However, little is known about the long-term dynamics and distribution patterns of deposited (DAMPs) and suspended (SAMPs) AMPs. In this study, simultaneous sampling was conducted over one year to examine the deposition-suspension distribution of AMPs. Monthly and seasonal variations in abundance were evident, with an annual average of 302.31 ± 107.40 items/m2/day for DAMPs and 1.31 ± 0.62 items/m3 for SAMPs. The dynamics of DAMP and SAMP abundance demonstrated the dynamic distribution of AMPs between deposition and suspension. Both meteorological factors and particle features were found to influence the AMP distribution, manifesting as morphological differences and abundance variations. AMPs were most likely derived from traffic, industry, construction, and synthetic textiles, with diverse source areas up to 1750 km away. The estimated deposition flux of 7.28 × 1014 items per year and inhalation exposure of up to 12,777 items per year highlight the potential ecological and health risks of AMPs.

O009 Are there Differences in SpO2 Recordings from Two Oximeters on the same hand during an Overnight Sleep Study Significant?

Abstract Background Accurate non-invasive oxygen saturation (SpO2) measurement is crucial in healthcare, however is challenged by numerous devices using variable algorithms1. We compared two commonly used oximeter devices worn simultaneously in patients during an overnight polysomnogram. Aim To assess (1) differences between two SpO2 recording devices and (2) SpO2 accuracy against SaO2. Methods SpO2 data of two devices were recorded, downloaded and analysed with corresponding software: device 1 (Rad7 [Masimo, Irvine, CA, USA] set at 2-4sec averaging time) with software 1 (PSG 4 [Compumedics, Melbourne, Australia]) and device 2 (Wrist-Ox2® [Nonin Medical Inc, Plymouth, MN, USA] set at 3 sec averaging time) with software 2 (Noxturnal [Nox Medical Inc, Reykjavik, Iceland]). Responsiveness of each oximeter to changes in the patients’ desaturations associated with apnoeas and hypopnoeas overnight was assessed. In addition, both device SpO2 values were compared with SaO2 from simultaneous arterial blood gas sampling. Preliminary Results 7 patients (age 56.4±7.1 years, BMI 31.6±2.2 kg/m2, 100% male, 87% light skinned) were studied. The mean SpO2 with RAD7 was higher than the Nonin (95.9±1.6 vs 94.2±1.4%, mean difference 1.6±1.0%). Differences in the responsiveness of the oximeters during overnight desaturations were also observed. However, both device SpO2 values were found to be within ±2% of SaO2. Conclusions Discrepancies in SpO2 measurement do occur between devices and may have important clinical implications especially when it comes to the measurement of hypoxemic burden during sleep. 1.Blanchet MA et al. Accuracy of Multiple Pulse Oximeters in Stable Critically Ill Patients. Respir Care. 2023 May;68(5):565-574.

Utilizing Ceftazidime/Avibactam Therapeutic Drug Monitoring in the Treatment of Neurosurgical Meningitis Caused by Difficult-to-Treat Resistant Pseudomonas aeruginosa and KPC-Producing Enterobacterales.

Central nervous system (CNS) infections caused by Klebsiella pneumoniae carbapenemase (KPC)-producing Enterobacterales and difficult-to-treat resistant (DTR) Pseudomonas aeruginosa represent a formidable clinical challenge. Antimicrobial regimens that efficiently penetrate the cerebrospinal fluid (CSF) and achieve sufficient concentrations associated with microbiologic and clinical cure are limited. We evaluated therapy with ceftazidime-avibactam (CAZ-AVI) in order to guide precise dosing in the treatment of CNS infections. Therapeutic drug monitoring (TDM) was performed in 3 patients with health care-associated ventriculitis and meningitis (HAVM) using CAZ-AVI 2.5 g infused intravenously every 8 hours as standard and extended infusion. Simultaneous CSF and plasma samples were obtained throughout the dosing interval in each patient. Concentrations of CAZ and AVI were determined by liquid chromatography/mass spectrometry. Bacterial identification revealed KPC-producing Klebsiella pneumoniae (KPC-Kp), DTR Pseudomonas aeruginosa, and KPC-producing Enterobacter cloacae (KPC-Ent.c). All isolates were resistant to carbapenems. The minimum inhibitory concentrations (MICs) of CAZ-AVI were 0.25/4, 4/4, and 0.25/4 μg/mL, respectively. CAZ and AVI concentrations were determined in CSF samples ranging from 29.0 to 15.0 µg/mL (CAZ component) and 4.20 to 0.92 µg/mL (AVI component), respectively. AVI achieved concentrations ≥1 µg/mL in 11 out of 12 CSF samples collected throughout the dosing interval. Clinical and microbiologic cure were attained in all patients. Postinfusion concentrations of CAZ-AVI were measured in plasma and CSF samples obtained from 3 patients with complicated CNS infections caused by antimicrobial-resistant isolates. The measured concentrations revealed that standard CAZ and AVI exposures sufficiently attained values correlating to 50% fT > MIC, which are associated with efficient bacterial killing.

THU014 Post-surgical Remission After Resection Of Solitary Mediastinal Lymph Node In A Metastatic Occult Ectopic ACTH Syndrome Patient

Abstract Disclosure: I.P. de Magalhães: None. C.P. Oliveira: None. L.P. Lins: None. N.X. Andrade: None. M.S. Lima: None. S.A. Siqueira: None. J.S. Fonini: None. E.C. Assis Filho: None. A.W. Mariani: None. M.C. Machado: None. BACKGROUND: The prevalence of occult cases has been increasing in the most recent series of Ectopic ACTH syndrome (EAS) maybe due to the small size of pulmonary neuroendocrine tumors. We present an atypical and very rare case of EAS with initial presentation of a single metastatic mediastinal lymph node that evolved with remission after your resection with no defined primary tumor. CASE REPORT: A 15-year-old female patient presented a clinical feature of Cushing’s syndrome (CS) with a 1-year evolution. Hormonal evaluation confirmed ACTH-dependent CS: urinary free cortisol of 819 µg/24h (3-43), late night salivary cortisol of 409 ng/dL (<274) and ACTH of 105 pg/mL (<63.3). Noninvasive methods for differential diagnosis of ACTH-dependent CS did not clarify the etiology (conflicting results): pituitary MRI negative, suppression of 59.6% of cortisol after high dose dexamethasone suppression test, positive response of ACTH and cortisol at desmopressin test, suppression of 81% of ACTH at acute octreotide SC test, negative serum tumor markers (gastrin, calcitonin, CEA, CA125, alpha-fetoprotein, CA19.9 and bhCG), negative cervical and pelvic ultrasound, negative computed tomography of thorax and negative abdominal MRI. Bilateral and simultaneous petrosal inferior sinus sampling with desmopressin confirmed EAS due to negative central to peripheral ACTH gradient, even after normalized PRL/ACTH gradients. Finally, PET/CT with Ga68-DOTATATE revealed a single infracarinal nodule of 1.5x0.6 cm with high capture of radioligand, SUVmax of 23.2, suggestive of affected mediastinal lymph node. The patient was submitted to thoracic surgery and the infracarinal lymph node was dissected and removed. Anatomopathological and immunohistochemical analyses disclosed a lymph node metastatic of a well-differentiated grade neuroendocrine tumor ACTH positive, Ki-67 2%. After surgery, the patient exhibited CS improvement and impressive drop of hormones at 5th postsurgical day (serum cortisol <1.0 µg/dL and ACTH of 2.2 pg/mL) confirming remission of CS. CONCLUSION: To our knowledge, approximately 36 cases of EAS due to neuroendocrine tumor of unknown primary origin were reported. However, previous cases commonly exhibited no remission after only removal of metastasis. Our case presented initial remission even with no primary tumor identified (occult primary tumor non-functioning?). Follow up with clinical, hormonal and imaging methods are necessary due to recurrence risk. Presentation: Thursday, June 15, 2023

Alveolar gradients in breath analysis. A pilot study with comparison of room air and inhaled air by simultaneous measurements using ion mobility spectrometry

Analyzing exhaled breath samples, especially using a highly sensitive method such as MCC/IMS (multi-capillary column/ion mobility spectrometry), may also detect analytes that are derived from exogenous production. In this regard, there is a discussion about the optimal interpretation of exhaled breath, either by considering volatile organic compounds (VOCs) only in exhaled breath or by additionally considering the composition of room air and calculating the alveolar gradients. However, there are no data on whether the composition and concentration of VOCs in room air are identical to those in truly inhaled air directly before analyzing the exhaled breath. The current study aimed to determine whether the VOCs in room air, which are usually used for the calculation of alveolar gradients, are identical to the VOCs in truly inhaled air. For the measurement of inhaled air and room air, two IMS, each coupled with an MCC that provided a pre-separation of the VOCs, were used in parallel. One device was used for sampling room air and the other for sampling inhaled air. Each device was coupled with a newly invented system that cleaned room air and provided a clean carrier gas, whereas formerly synthetic air had to be used as a carrier gas. In this pilot study, a healthy volunteer underwent three subsequent runs of sampling of inhaled air and simultaneous sampling and analysis of room air. Three of the selected 11 peaks (P4—unknown, P5—1-Butanol, and P9—Furan, 2-methyl-) had significantly higher intensities during inspiration than in room air, and four peaks (P1—1-Propanamine, N-(phenylmethylene), P2—2-Nonanone, P3—Benzene, 1,2,4-trimethyl-, and P11—Acetyl valeryl) had higher intensities in room air. Furthermore, four peaks (P6—Benzaldehyde, P7—Pentane, 2-methyl-, P8—Acetone, and P10—2-Propanamine) showed inconsistent differences in peak intensities between inhaled air and room air. To the best of our knowledge, this is the first study to compare simultaneous sampling of room air and inhaled air using MCC/IMS. The simultaneous measurement of inhaled air and room air showed that using room air for the calculation of alveolar gradients in breath analysis resulted in different alveolar gradient values than those obtained by measuring truly inhaled air.

Resource frugal optimizer for quantum machine learning

Abstract Quantum-enhanced data science, also known as quantum machine learning (QML), is of growing interest as an application of near-term quantum computers. Variational QML algorithms have the potential to solve practical problems on real hardware, particularly when involving quantum data. However, training these algorithms can be challenging and calls for tailored optimization procedures. Specifically, QML applications can require a large shot-count overhead due to the large datasets involved. In this work, we advocate for simultaneous random sampling over both the dataset as well as the measurement operators that define the loss function. We consider a highly general loss function that encompasses many QML applications, and we show how to construct an unbiased estimator of its gradient. This allows us to propose a shot-frugal gradient descent optimizer called Refoqus (REsource Frugal Optimizer for QUantum Stochastic gradient descent). Our numerics indicate that Refoqus can save several orders of magnitude in shot cost, even relative to optimizers that sample over measurement operators alone.

Monitoring of cyanobacterial breakthrough and accumulation by in situ phycocyanin probe system within full-scale treatment plants

Worldwide, there has been an increase in the presence of potentially toxic cyanobacterial blooms in drinking water sources and within drinking water treatment plants (DWTPs). The objective of this study is to validate the use of in situ probes for the detection and management of cyanobacterial breakthrough in high and low-risk DWTPs. In situ phycocyanin YSI EXO2 probes were devised for remote control and data logging to monitor the cyanobacteria in raw, clarified, filtered, and treated water in three full-scale DWTPs. An additional probe was installed inside the sludge holding tank to measure the water quality of the surface of the sludge storage tank in a high-risk DWTP. Simultaneous grab samplings were carried out for taxonomic cell counts and toxin analysis. A total of 23, 9, and 4 field visits were conducted at the three DWTPs. Phycocyanin readings showed a 93-fold fluctuation within 24 h in the raw water of the high cyanobacterial risk plant, with higher phycocyanin levels during the afternoon period. These data provide new information on the limitations of weekly or daily grab sampling. Also, different moving averages for the phycocyanin probe readings can be used to improve the interpretation of phycocyanin signal trends. The in situ probe successfully detected high cyanobacterial biovolumes entering the clarification process in the high-risk plant. Grab sampling results revealed high cyanobacterial biovolumes in the sludge for both high and low-risk plants.

246-LB: Stimulation of Hepatic Lipid Secretion by Glucocorticoid Action in the Nucleus of the Solitary Tract

Dysregulated lipid metabolism is a characteristic of diabetes, insulin resistance, and obesity. Increased glucocorticoid (GC) levels and/or action is associated with elevated levels of circulating triglyceride (TG)-rich very low-density lipoproteins (VLDL-TGs). Lipid metabolism is heavily affected by GCs via its direct actions on peripheral organs, e.g. liver, adipose tissue. However, how GCs modulate hepatic VLDL-TG secretion via their actions in the brain is less known. The nucleus of the solitary tract (NTS) in the hindbrain is responsive to various hormones and is an important region involved in whole-body metabolism. Here, we aimed to assess how GC action in the NTS affects hepatic TG secretion and hypothesized that GC receptor (GR) agonism in the NTS stimulates hepatic TG secretion. Sprague-Dawley rats underwent stereotaxic NTS bilateral cannulation and vascular catheterizations to enable simultaneous direct NTS infusions, intravenous injections, and blood sampling. Hepatic TG secretion rates were measured in 10h-fasted rats after intravenous poloxamer injection with concurrent NTS infusions. NTS GC infusion stimulated TG secretion compared to NTS vehicle controls, but this effect was negated with pharmacological and genetic GR antagonism, suggesting that NTS GCs are mediated via its receptor. The NTS GC-induced increase in VLDL-TG was not associated with changes in liver lipogenic gene expression and protein levels or plasma ApoB48/100. However, plasma FFAs were increased in NTS GC infused rats, and this was associated with increased pHSL:HSL protein levels in white adipose tissue. We herein provide evidence that acute GC action in the NTS stimulates hepatic VLDL-TG secretion and affects adipose tissue lipid metabolism. Increased circulating FFA availability may contribute to the hyperlipidemic effects of NTS GCs. Future studies to assess the role of NTS GC action in diabetic and obesity-related metabolic disease dyslipidemic models are warranted. Disclosure B. Vasilev: None. M. S. Grewal: None. B. Lum: None. J. T. Yue: None. Funding Natural Sciences and Engineering Research Council of Canada (RGPIN-2016-06657); Canada Foundation for Innovation (37267); Canada Research Chairs Tier 2 in Brain Regulation of Metabolism

Overview of Signal Processing Problems in Power Electronic Control Circuits

This paper examines various aspects related to digital signal processing in digital control circuits used in power electronics. The discussion focuses on several common issues, including the sampling rate of signals (including phenomena such as aliasing and synchronization), coherent sampling, jitter of sampling pulses, sequential versus simultaneous sampling in multichannel systems, signal resolution (including signal-to-noise ratio, noise-shaping circuits, and changes in sampling speed), interpolation and decimation, and the conversion of analog circuits into digital form. One of the key contributions of this paper is the introduction of a new formula for calculating the resultant signal-to-noise ratio for three-stage digital control circuits. By carefully considering and correcting for sources of error, it is possible to increase the signal-to-noise ratio and minimize distortion components. This, in turn, leads to improved output/input current and voltage parameters, which can have a positive impact on the overall quality of energy processing in power electronic circuits.

RENAL SYMPATHETIC DENERVATION AND NEURO-HORMONAL EVALUATION BY SELECTIVE VENOUS CATHETERIZATION: THE RESIDENCY STUDY

Objective: Renal denervation (RD) is effective in reducing blood pressure (BP) in hypertensive patients, but the pathophysiologic mechanisms underlying the variable individual response are unclear and early markers of procedural success are lacking. The aim of the study was to evaluate intra-/peri-operative effects of RD on the renin-angiotensin-aldosterone system (RAAS) either as determinants and markers of efficacy. Design and method: Patients with resistant hypertension and eGFR>45 ml/min underwent radiofrequency-RD (Medtronic Symplicity-Spyral) with simultaneous sampling of the renal veins (RV), left adrenal vein and pre-renal inferior vena cava (IVC). Samples were collected before (t0) and 15’ after RD from each sequentially-approached side. Additional peripheral blood samples collected on the morning before RD and 3h, 24h and 7 days after the procedure were tested for renin, aldosterone and cortisol. During this timeframe, antihypertensive therapy remained unchanged. Results: Ten patients were recruited (61±11yo; 30%F; BP = 149/84 ±11/12 mmHg on 4 (range 3-6) antihypertensive drugs). Peripheral renin concentration showed no significant changes during/immediately after RD and up to 7 days after, in spite of the observed BP reduction (136/78 ±17/15 mmHg; p<0.05). Similarly, RV renin was unaffected by ipsilateral RD compared to the corresponding t0 values (p = 0.899). Aldosterone and cortisol increased in the adrenal vein during RD (p<0.001), but their IVC-corrected ratio and their peripheral plasma concentrations at follow-up did not, likely reflecting a self-limiting stress reaction. Conclusions: These results do not suggest any direct blunting effect of RD on RAAS, and do not support the contention of monitoring acute RAAS changes as proxies for procedural effectiveness.

Deconvolution of Plasma Pharmacokinetics from Dynamic Heart Imaging Data Obtained by Single Positron Emission Computed Tomography/Computed Tomography Imaging.

Plasma pharmacokinetic (PK) data are required as an input function for graphical analysis of single positron emission computed tomography/computed tomography (SPECT/CT) and positron emission tomography/CT (PET/CT) data to evaluate tissue influx rate of radiotracers. Dynamic heart imaging data are often used as a surrogate of plasma PK. However, accumulation of radiolabel in the heart tissue may cause overprediction of plasma PK. Therefore, we developed a compartmental model, which involves forcing functions to describe intact and degraded radiolabeled proteins in plasma and their accumulation in heart tissue, to deconvolve plasma PK of 125I-amyloid beta 40 (125I-Aβ 40) and 125I-insulin from their dynamic heart imaging data. The three-compartment model was shown to adequately describe the plasma concentration-time profile of intact/degraded proteins and the heart radioactivity time data obtained from SPECT/CT imaging for both tracers. The model was successfully applied to deconvolve the plasma PK of both tracers from their naïve datasets of dynamic heart imaging. In agreement with our previous observations made by conventional serial plasma sampling, the deconvolved plasma PK of 125I-Aβ 40 and 125I-insulin in young mice exhibited lower area under the curve than aged mice. Further, Patlak plot parameters extracted using deconvolved plasma PK as input function successfully recapitulated age-dependent plasma-to-brain influx kinetics changes. Therefore, the compartment model developed in this study provides a novel approach to deconvolve plasma PK of radiotracers from their noninvasive dynamic heart imaging. This method facilitates the application of preclinical SPECT/PET imaging data to characterize distribution kinetics of tracers where simultaneous plasma sampling is not feasible. SIGNIFICANCE STATEMENT: Knowledge of plasma pharmacokinetics (PK) of a radiotracer is necessary to accurately estimate its plasma-to-brain influx. However, simultaneous plasma sampling during dynamic imaging procedures is not always feasible. In the current study, we developed approaches to deconvolve plasma PK from dynamic heart imaging data of two model radiotracers, 125I-amyloid beta 40 (125I-Aβ 40) and 125I-insulin. This novel method is expected to minimize the need for conducting additional plasma PK studies and allow for accurate estimation of the brain influx rate.

Sampling chamber with minimal wall surface for simultaneous emission testing of diisocyanates and diamines from polyurethane products

A sampling chamber was developed for emission testing of diisocyanates, methylene diphenyl diisocyanate (MDI), toluene diisocyanate (TDI), and corresponding diamines, methylene diphenyl diamine (MDA), and toluene diamine (TDA) from polyurethane (PU) product surfaces. In addition, a methodology for validation of the sampling chamber was presented, based on the introduction of generated standard atmospheres of the different diisocyanates and diamines to the sampling chamber system. Sampling of diisocyanates and diamines was performed on a circular glass fiber filter (150mm diameter) impregnated with dihexyl amine (DHA) and acetic acid (AA) positioned inside a cylindrical stainless steel sampling chamber. The diisocyanates were immediately derivatized to DHA derivatives, and the amines were derivatized in a subsequent work-up procedure with ethyl chloroformate (ECF). The design of the sampling chamber and the presented methodology allowed for simultaneous sampling and analysis of diisocyanates and diamines of emission from a large surface area with minimal interior wall interaction in the sampling chamber. Performance characteristics of the sampling chamber for different sampling times and air humidity were obtained by determining collected amounts of the diisocyanates and diamines in the different parts of the sampling chamber. The repeatability of the collected amount on the impregnated filters in the sampling chamber was 15% with an overall recovery for 8h of sampling in the range of 61% to 96%. The performance of the sampling chamber was not affected by air humidity (5%-75% RH), and no breakthrough during sampling was observed. LC-MS/MS determinations allowed for emission testing of diisocyanates and diamines on product surfaces as low as 10-30ng m-2 h-1.

GPU-specific algorithms for improved solute sampling in grand canonical Monte Carlo simulations.

The Grand Canonical Monte Carlo (GCMC) ensemble defined by the excess chemical potential, μex , volume, and temperature, in the context of molecular simulations allows for variations in the number of particles in the system. In practice, GCMC simulations have been widely applied for the sampling of rare gasses and water, but limited in the context of larger molecules. To overcome this limitation, the oscillating μex GCMC method was introduced and shown to be of utility for sampling small solutes, such as formamide, propane, and benzene, as well as for ionic species such as monocations, acetate, and methylammonium. However, the acceptance of GCMC insertions is low, and the method is computationally demanding. In the present study, we improved the sampling efficiency of the GCMC method using known cavity-bias and configurational-bias algorithms in the context of GPU architecture. Specifically, for GCMC simulations of aqueous solution systems, the configurational-bias algorithm was extended by applying system partitioning in conjunction with a random interval extraction algorithm, thereby improving the efficiency in a highly parallel computing environment. The method is parallelized on the GPU using CUDA and OpenCL, allowing for the code to run on both Nvidia and AMD GPUs, respectively. Notably, the method is particularly well suited for GPU computing as the large number of threads allows for simultaneous sampling of a large number of configurations during insertion attempts without additional computational overhead. In addition, the partitioning scheme allows for simultaneous insertion attempts for large systems, offering considerable efficiency. Calculations on the BK Channel, a transporter, including a lipid bilayer with over 760,000 atoms, show a speed up of ~53-fold through the use of system partitioning. The improved algorithm is then combined with an enhanced μex oscillation protocol and shown to be of utility in the context of the site-identification by ligand competitive saturation (SILCS) co-solvent sampling approach as illustrated through application to the protein CDK2.

A Study of Elemental Composition and Risk Assessment Due to Exposure to Indoor PM10 in Two Residences in Mexico City

Samples of airborne particles with aerodynamic diameters smaller than 10 µm (PM10) were collected in 2021 at two households in the Metropolitan Area of Mexico City. Both sites are in areas with different characteristics (residential or industrial zones). Simultaneous sampling indoors and outdoors was carried out at the two locations, using low-volume samplers. The study aimed to determine the indoor and outdoor gravimetric mass and elemental concentrations, identify emitting sources and possible penetration towards the households enhanced by natural ventilation, and assess risks to human health due to inhalation, ingestion, and dermal absorption, through hazard quotients. Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Se, and Pb concentrations were measured with X-ray fluorescence. Mass concentrations were higher indoors than outdoors, and most elemental concentrations had similar values in both environments. Cluster analysis was applied to identify possible emitting sources. The results showed a strong penetration of geogenic and industrial emissions at the Iztapalapa site, while only particles of industrial origin entered the interior of the Tlalnepantla dwelling, in both cases caused by the natural ventilation of the households. Health risks due to exposure to particles containing Fe, Ni, Cu, Zn, and Mn are not significant, and Pb and Cr only pose a risk via ingestion for men and women, although for children, there is a risk due to ingestion of all these elements.

New Trend in Toxicological Screening Using Volumetric Absorptive Microsampling (VAMS) and High-Resolution Mass Spectrometry (HR/MS) Combination.

In toxicology, screenings are routinely performed using chromatographic methods coupled to detection systems such as high-resolution mass spectrometry (HR/MS). The increase in specificity and sensitivity of HRMS is responsible for the development of methods for alternative samples such as Volumetric Adsorptive Micro-Sampling. Whole blood overloaded with 90 drugs was sampled with 20 µL MitraTM to optimize the pre-analytical step as well as to determine the identification limits of drugs. Elution of chemicals was carried out in a solvent mixture through agitation and sonication. After dissolution, 10 μL was injected into the chromatographic system coupled to the OrbitrapTM HR/MS. Compounds were confirmed against the laboratory library. The clinical feasibility was assessed in fifteen poisoned patients using the simultaneous sampling of plasma, whole blood and MitraTM. The optimized extraction procedure allowed us to confirm 87 compounds out of the 90 present in the spiked whole blood. Cannabis derivatives were not detected. For 82.2% of the investigated drugs, the identification limits were below 12.5 ng·mL-1, with the extraction yields ranging from 80.6 to 108.7%. Regarding the patients' analysis, 98% of the compounds in plasma were detected in MitraTM compared to whole blood, with a satisfying concordance (R2 = 0.827). Our novel screening approach opens new insights into different toxicologic fields appropriate for pediatrics, forensics or to perform mass screening.

Signatures of Reaction Mechanisms Encoded in the Vibrational Population Distribution of Small-Molecule Products: Photodissociation of Symmetric-Triazine Using 266 nm Radiation

We utilize rotationally resolved Chirped-Pulse Fourier Transform millimeter-wave spectroscopy to study photodissociation dynamics of 1,3,5-Triazine (symmetric-Triazine) to form 3 HCN molecules. The state-specific vibrational population distribution (VPD) of the photofragments contains mechanistic details of the reaction. This photodissociation is performed using 266 nm radiation transverse to a seeded supersonic jet. The vibrational cooling inefficiency in the jet preserves the VPD of the photofragments, while rotational cooling enhances the signal of low-J pure-rotational transitions. The multiplexed nature of the spectrometer enables simultaneous sampling of several "vibrational satellites" of the J = 1 ← 0 transition of HCN. Excited state populations along the HCN bend (v2) and CN stretch (v3) modes are observed, which show ≥3.2% vibrational excitation of the photofragments. Observation of an at least bimodal VPD, along the even-v states of v2, implies an asymmetric partitioning of vibrational energy among the HCN photofragments. This suggests a sequential dissociation mechanism of symmetric-Triazine initiated by 266 nm radiation.

A Clockless Synergistic Hybrid Energy Harvesting Technique With Simultaneous Energy Injection and Sampling for Piezoelectric and Photovoltaic Energy

In this paper, a mutually synergistic hybrid energy harvesting (SHEH) circuit with both AC and DC energy harvesting capability is proposed. Within the proposed hybrid harvester, the vibration period of the piezoelectric transducer (PZT) is served as the switching signal for photovoltaic (PV) energy harvesting so that a dedicated clock generator is saved. Meanwhile, during the sampling phase, a small portion of the PV energy is injected into the PZT as an investment, which enhances the damping force and charge extraction of the PZT. Theoretically, the total synergistically extracted power from the proposed hybrid harvester is more than the sum of the power obtained from each transducer independently. The proposed SHEH circuit is fabricated with a 0.18- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> CMOS process. The buck-boost converter with zero-current switching control achieves a peak efficiency of 82.8%, and the maximum efficiency of piezoelectric energy harvesting can reach 4.5 times that of the full-bridge rectifier.

Experimental evaluation of dimensionless extinction coefficient of soot in co-flow laminar diffusion flames at elevated pressures

Dimensionless extinction coefficient (Ke) is one of the most important optical parameters of soot since it affects the accuracy of laser extinction measurement of soot volume fraction. In literature, Ke values have been measured for soot from laminar and turbulent flames with different fuels at atmospheric pressure. However, relevant studies about the measurement of Ke values in flames at elevated pressures are still lacking. In this study, a simultaneous gravity sampling and laser extinction system (GSLE) capable of operating in a combustion chamber was proposed to evaluate the value of Ke in laminar diffusion flames at elevated pressures. Methane and two straight-chain alkanes (n-heptane and n-dodecane) were selected as fuels for comparative studies at 0.1–0.8 MPa and 0.1–0.5 MPa, respectively. The morphology properties of soot samples were analyzed quantitatively by transmission electron microscopy (TEM). The results show the Ke values of in-flame soot for methane, n-heptane, and n-dodecane range from 6.1 to 9.7, 6.5 to 10.7, and 7.4 to 10.9 at the corresponding experimental pressures, respectively. The Ke values of in-flame soot for all three fuels increase with pressure. The above results conclude that using a constant Ke value measured at atmospheric pressure may result in larger errors in the measurement of soot volume fraction in flames at elevated pressure. The quantitative analysis of TEM images shows that the significant variation of soot morphology parameters with pressure is one of the main factors for the variation of Ke value with pressure.