Surrogate Source Research Articles

Nickel-catalyzed decarbonylation of aryl anhydrides for the synthesis of thioesters and thioethers: CS2/DBU as a surrogate sulfur source

A novel strategy for C–S bond formation is developed. This reaction utilizes a low-cost, air- and moisture-insensitive nickel pre-catalyst to execute a decarbonylative reaction of acid anhydrides, followed by reaction with an odorless and manageable carbon disulfide, to synthesize various thioesters and thioethers. The process accommodated various acid anhydrides and yielded products in good to excellent quantities.

Experimental validation of Monte Carlo NaI(Tl) detector efficiency responses with surrogate 137Cs environmental contamination source term

Radiological site remediation is a resource intensive process requiring extensive field sampling to demonstrate regulatory compliance. Specifically, the application of Monte Carlo (MC) simulations and automated hybrid radiation transport methods has garnered interest in streamlining the remediation process by simulating detector responses for a plurality of contaminated media, contamination depths and profiles, and source-detector orientations. In this study, experimental validation of gamma-ray detector efficiency responses was conducted for simulations of radiological site-specific and idealized external contamination conditions. Measurements were performed with a cylindrical 2′′ × 2″ sodium iodide thallium-doped (NaI(Tl)) scintillator detector suspended above a 217.8 kBq, 50 cm × 50 cm 137Cs contamination source located on the surface of or buried within environmental soil. New area correction factors (ACFs) and gamma shielding factors (GSFs) were also derived to modify the simulated idealized detector efficiency responses, accounting for reductions in source area and clean soil covering layers, respectively, that may be encountered when performing in-situ gamma spectrometry in the field. The study concluded that simulated total detection efficiency from energy deposition in the active volume of the detector crystal can be adopted for radionuclide screening purposes. Furthermore, pragmatic implementation of environmental surveying using gamma-spectrometry requires site-specific information.

Screening and characterization of waste lignocellulosic biomass as a potential substrate for energy recovery

AbstractThe world is facing a severe energy crisis due to rapid industrialization, population explosion, and modern lifestyle. Conventional energy sources are running out of stock and accordingly, an ardent need for the search for alternative feedstock for energy recovery has been the research focus for the past few decades. In context to this energy turmoil, the lignocellulosic biomasses have emerged as an excellent surrogate antecedent for energy procreation in this present scenario of the energy crisis. Among numerous feasible biomass energy recovery methods, the biochemical route and the thermochemical route are the most prevailing. Accordingly, several biomass characteristics require well understanding to access the extent of possible energy recovery. The compositional features assessed (in terms of cellulose, hemicellulose, extractives, and lignin content) as well as the ultimate analysis carried out (in terms of the carbon, hydrogen, oxygen, sulfur, and nitrogen content) as one of the major parameters for evaluating the energy recovery potential and subsequently, a Van Krevelen diagram was obtained to define their energy recovery potential. The calorific value of the three biomass specimens obtained by using an adiabatic bomb calorimeter and subsequently, their oil equivalence was presented. A tariff and budgetary analysis evaluated to define their respective economic incentives and their potential scope to meet the energy crisis scenario. Finally, a scoring matrix analysis conducted parallelly by evaluating the various parameters by adopting the rank correlation method to screen out the best biomass category. The overall scheme of study adopted for screening a particular waste biomass category from three widely available agriculture waste biomass samples (rice husk, corn cob, and nutshell) through multiple criteria and thereby evaluating the most ideal biomass as the surrogate source to meet the ever‐increasing energy demand which are prevalent in the state of Jharkhand, India.

TBAI-Mediated Cyclization and Methylsulfonylation of Propargylic Amides with Dimethyl Sulfite.

A tetramethylammonium iodide (TBAI)-mediated cyclization and methylsulfonylation of propargylic amides enabled by dimethyl sulfite as a SO2 surrogate and methyl source have been developed. The transition metal-free and oxidant-free reaction provides a practical and efficient approach for the selective synthesis of methylsulfonyl oxazoles in moderate to excellent yields with good functional group compatibility.

Abstract P1-05-35: Identification of Circulating Tumor Cells captured by the FDA Cleared Parsortix® PC1 System from the Peripheral Blood of Metastatic Breast Cancer Patients using Immunofluorescence and Cytopathological Evaluations

Abstract Background: Circulating tumor cells (CTCs) captured from the blood of cancer patients may serve as a non-invasive surrogate source of tumor material to investigate tumor characteristics in real-time. The Parsortix® PC1 System, the first FDA-cleared medical device for the capture and harvest of CTCs from peripheral blood of metastatic breast cancer (MBC) patients for use in subsequent user-validated downstream analyses, enables the epitope independent capture of CTCs with diverse phenotypes based on cell size and deformability. In this study, CTCs isolated from the blood of MBC patients by the Parsortix® PC1 System were identified using an immunofluorescence (IF) based assay for detection of epithelial CTCs followed by Wright-Giemsa staining and cytomorphological review. The aim of this study was to determine the proportion of MBC patients and self-declared female healthy volunteers (HVs) that had one or more CTCs identified in the population of cells harvested from their peripheral blood by the Parsortix® PC1 System. Methods: Peripheral blood from 75 HVs and 77 patients with MBC was prospectively collected into K2EDTA tubes at the University of Rochester Medical Center. The blood collected from each subject (8.6±1.2mL) was processed on a Parsortix® PC1 System within 8 hours of collection. The cells harvested by the system were cytospun onto a charged slide and IF stained using an optimised antibody panel. The IF panel consisted of a nuclear dye (DAPI), positive selection markers targeting epithelial CTCs (Cytokeratins (CK) and EpCAM), and negative selection markers targeting white blood cells, such as lymphocytes, macrophages, granulocytes, monocytes, fibroblasts, and cells of megakaryoblastic potential. The stained slides were imaged using fluorescence microscopy and CTCs were defined as nucleated cells (DAPI+) that were positive for CK and/or EpCAM and negative for the blood lineage markers. The IF slides were subsequently stained with Wright-Giemsa and analysed by a qualified pathologist using light microscopy. Morphological features of malignant cells were used to define and identify CTCs. All laboratory testing and analysis was performed by operators blinded to the clinical status of each subject. Results: On the evaluable IF-stained slides, cells classified as CTCs based on their IF staining pattern were identified in 45.3% (34/75) of the MBC patients (range = 0 – 125 CTCs, mean = 7) and in 5.6% (4/71) of the HVs (range = 0 – 8 CTCs, mean = 0). No EpCAM+, CK- CTCs were identified in either MBC patients or HVs. In the 34 MBC patients with one or more CTCs observed, 70.6% had only CK+, EpCAM- cells, while the remaining 29.4% had at least one CK+, EpCAM+ cell. In the HVs, one out of the four CTC-positive donors had only CK+, EpCAM+ cells while the other three had only CK+, EPCAM- cells. On the evaluable Wright-Giemsa stained slides, cells classified as CTCs by the pathologist were identified in 57.1% (40/70) of the MBC patients (range = 0 – 41 CTCs, mean = 4) and in 4.4% (3/68) of the HVs (range = 0 – 14, mean = 0). Conclusions: This study demonstrated the ability of ANGLE’s Parsortix® PC1 System to capture and harvest CTCs from a significantly larger proportion of MBC patients compared to HV subjects. The presence of epithelial cells in subjects without diagnosed disease has been previously described in the literature, with their significance being unclear. This study also demonstrated that the cells harvested by the Parsortix® PC1 System can be successfully evaluated using both IF staining and Wright-Giemsa cytomorphological assessment for the identification of CTCs. Interestingly, a high proportion of the identified CTCs did not express EpCAM, further highlighting the limitations of using EpCAM-based approaches to capture CTCs. Citation Format: Mariacristina Ciccioli, Richard Moore, Kyu Kwang Kim, Negar Khazan, Michael C. Miller, Anne-Sophie Pailhes-Jimenez. Identification of Circulating Tumor Cells captured by the FDA Cleared Parsortix® PC1 System from the Peripheral Blood of Metastatic Breast Cancer Patients using Immunofluorescence and Cytopathological Evaluations [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-05-35.

Abstract P5-06-01: A Multi-center Clinical Study to Harvest and Characterize Circulating Tumor Cells from Patients with Metastatic Breast Cancer Using the Parsortix® PC1 System in support of FDA clearance

Abstract Background: Circulating tumor cells (CTCs) captured from the blood of cancer patients may serve as a non-invasive surrogate source of tumor material to investigate tumor characteristics in real-time. However, the only FDA-cleared CTC assay is limited to the enumeration of surface marker-defined epithelial cells and not designed for further characterization of the CTCs identified. The Parsortix® PC1 system is a semi-automated microfluidic device capable of capturing and harvesting CTCs from peripheral blood based on cell size and deformability, making it cell-surface marker agnostic. Here, we demonstrate that the Parsortix® PC1 system enables the enrichment and capture of CTCs from the blood of patients with metastatic breast cancer (MBC) and their interrogation using evaluation techniques commonly available in clinical laboratories. Methods: As part of a multicenter clinical trial (NCT03427450), peripheral blood samples from 216 patients with MBC and 205 healthy volunteers (HVs) were prospectively collected at four different clinical sites located throughout the United States. Each subject provided two separate blood samples collected into K2EDTA Vacutainer® tubes to be processed using the Parsortix® PC1 system on the same day. The cells harvested from one of the blood samples collected from each subject by the Parsortix® PC1 system were deposited onto cytology slides using a cytocentrifugation method and stained with Wright-Giemsa reagents using an automated stainer. The stained slides were subjected to cytopathological evaluation by a board-certified pathologist to enumerate CTCs. As proof of principle, cells harvested from the second blood sample were evaluated using one of three additional techniques: molecular profiling by qRT-PCR, RNA sequencing, or cytogenetic analysis of HER2 amplification by FISH. Results: Cytologic examination identified one or more cells as a CTC in 48.5% (95% CI of 41.5 – 55.4%) of the 194 patients with MBC and 9.9% (95% CI of 6.4 – 14.9%) of the 192 HVs. The results from the qRT-PCR evaluation (102 HVs and 74 MBC patients) showed differential expression of cancer-related genes (KRT19, EPCAM, and TWIST1) in the patients with MBC compared to the HVs. Results from the RNA sequencing (53 HVs and 16 MBC patients) showed differential expression of several genes involved in the Kegg Cancer Pathway in the patients with MBC compared to the HVs. The results from the HER2 FISH evaluation (38 HVs and 101 MBC patients) showed that while the majority of the CTC identified had normal HER2/CEP17 ratios, detection of HER2 amplification was possible. Conclusions: The Parsortix PC1 system is capable of capturing and harvesting CTCs from the peripheral blood of patients with MBC. Harvested cells can be evaluated using standard orthogonal methodologies such as gene expression and FISH to identify and characterize CTCs. Based in part on the above results, the FDA granted a De Novo classification request (DEN200062) for the Parsortix PC1 device in May of 2022. Citation Format: Evan Cohen, Gitanjali Jayachandran, Richard Moore, Massimo Cristofanilli, Julie E. Lang, Joseph Khoury, Michael F. Press, Heather McBride, Kyu Kwang Kim, Negar Khazan, Qiang Zhang, Youbin Zhang, Roberta Guzman, Michael C. Miller, James Reuben, Naoto T. Ueno. A Multi-center Clinical Study to Harvest and Characterize Circulating Tumor Cells from Patients with Metastatic Breast Cancer Using the Parsortix® PC1 System in support of FDA clearance [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P5-06-01.

A Multi-Center Clinical Study to Harvest and Characterize Circulating Tumor Cells from Patients with Metastatic Breast Cancer Using the Parsortix® PC1 System.

Circulating tumor cells (CTCs) captured from the blood of cancer patients may serve as a surrogate source of tumor material that can be obtained via a venipuncture (also known as a liquid biopsy) and used to better understand tumor characteristics. However, the only FDA-cleared CTC assay has been limited to the enumeration of surface marker-defined cells and not further characterization of the CTCs. In this study, we tested the ability of a semi-automated device capable of capturing and harvesting CTCs from peripheral blood based on cell size and deformability, agnostic of cell-surface markers (the Parsortix® PC1 System), to yield CTCs for evaluation by downstream techniques commonly available in clinical laboratories. The data generated from this study were used to support a De Novo request (DEN200062) for the classification of this device, which the FDA recently granted. As part of a multicenter clinical trial, peripheral blood samples from 216 patients with metastatic breast cancer (MBC) and 205 healthy volunteers were subjected to CTC enrichment. A board-certified pathologist enumerated the CTCs from each participant by cytologic evaluation of Wright-Giemsa-stained slides. As proof of principle, cells harvested from a concurrent parallel sample provided by each participant were evaluated using one of three additional evaluation techniques: molecular profiling by qRT-PCR, RNA sequencing, or cytogenetic analysis of HER2 amplification by FISH. The study demonstrated that the Parsortix® PC1 System can effectively capture and harvest CTCs from the peripheral blood of MBC patients and that the harvested cells can be evaluated using orthogonal methodologies such as gene expression and/or Fluorescence In Situ Hybridization (FISH).

Design and synthesis of highly efficient nitrogen-doped carbon nano-onions for asymmetric supercapacitors

The preparation of highly graphitic carbon materials encourages the synthesis of sustainable energy storage for fast charging power applications. In this consideration, at present work, porous nitrogen-doped carbon nano-onions (N-CNO) were prepared by a different strategic, simple, low-cost, one-step pyrolysis technique. The fabricated material was characterized by various physical and electroanalytical measurements. The D, G, and 2D bands from Raman and pyridinic-N, pyrrolic-N, graphitic-N, and pyridinic-N-O from the X-ray photoelectron spectroscopy confirmed the graphitic nature of the N-CNO material. The results of specific capacitance for the as-grown materials containing N-CNO at a current density of 1 A/g have achieved a specific capacitance of 234 F g− 1. Moreover, the retention of N-CNO after 5000 long charge/discharge was 98%. The utilizing voltages of the synthesized asymmetric devices were expanded to 1.6 V in 2 M KOH solution, providing a notable specific capacitance of 79 F g−1 and higher energy densities of 27.2 Wh kg−1 at 1 A g−1. Mainly, even at higher current densities (10 A/g) this device still holds higher power densities (7.5 kW kg−1) while keeping 12 Wh kg−1 energy densities. Nevertheless, the well-being asymmetric device explores notable electrochemical cycling stabilities and capacitance retention of 98% over 5000 at 8 A g−1. These values evident that N–CNO will have been utilized as a surrogate electrode source and a potential candidate in SCs with higher specifical energy/power densities.

Comparative Genomics Identifies Features Associated with Methicillin-Resistant Staphylococcus aureus (MRSA) Transmission in Hospital Settings.

ABSTRACTMethicillin-resistant Staphylococcus aureus (MRSA) is a serious public health concern in the United States. Patients colonized and/or infected can transmit MRSA to healthcare workers and subsequent patients However, the components of this transmission chain are just becoming evident, including certain patient factors, specific patient-healthcare worker interactions, and microbial factors. We conducted a comparative genomic analysis of 388 isolates from four hospitals in three states: Maryland, California, and New York. Isolates from nasal surveillance or clinical cultures were categorized as high, moderate, or low transmission surrogate outcomes based on the number of times the species was identified on the gloves or gowns of healthcare providers. The comparative analyses included a single gene, multigene, and core genome phylogenetic analysis, as well as a genome-wide association analysis to identify molecular signatures associated with the observed transmission surrogate outcomes, geographic origin, or sample source of isolation. Based on the phylogenetic analysis, 95% (n = 372) of the MRSA isolates were from four well-described genomic clades, with most of the isolates being part of the USA300 containing clade (n = 187; 48%). Genome-wide association studies also identified genes that were exclusive or prevalent among specific geographic locations. The identified genes provide insights into the transmission dynamics of MRSA isolates providing additional insights into the basis of the geographical differences of MRSA for molecular diagnostics.IMPORTANCE Methicillin-resistant Staphylococcus aureus (MRSA) is considered a serious threat to public health and contributes to the dissemination of S. aureus in both the healthcare and community setting. Transmission of MRSA between patients via healthcare worker (HCW) has been described. However, what is not understood are the genetic determinants that contribute to the transmission of MRSA from patients to HCWs. In this study, we demonstrated that certain genes may be associated with transmission in the hospital setting.

EEG-fMRI: Ballistocardiogram Artifact Reduction by Surrogate Method for Improved Source Localization.

For the analysis of simultaneous EEG-fMRI recordings, it is vital to use effective artifact removal tools. This applies in particular to the ballistocardiogram (BCG) artifact which is difficult to remove without distorting signals of interest related to brain activity. Here, we documented the use of surrogate source models to separate the artifact-related signals from brain signals with minimal distortion of the brain activity of interest. The artifact topographies used for surrogate separation were created automatically using principal components analysis (PCA-S) or by manual selection of artifact components utilizing independent components analysis (ICA-S). Using real resting-state data from 55 subjects superimposed with simulated auditory evoked potentials (AEP), both approaches were compared with three established BCG artifact removal methods: Blind Source Separation (BSS), Optimal Basis Set (OBS), and a mixture of both (OBS-ICA). Each method was evaluated for its applicability for ERP and source analysis using the following criteria: the number of events surviving artifact threshold scans, signal-to-noise ratio (SNR), error of source localization, and signal variance explained by the dipolar model. Using these criteria, PCA-S and ICA-S fared best overall, with highly significant differences to the established methods, especially in source localization. The PCA-S approach was also applied to a single subject Berger experiment performed in the MRI scanner. Overall, the removal of BCG artifacts by the surrogate methods provides a substantial improvement for the analysis of simultaneous EEG-fMRI data compared to the established methods.

Arenesulfonyl fluoride synthesis via one-pot copper-free Sandmeyer-type three-component reaction of aryl amine, K2S2O5, and NFSI

A one-pot procedure for the synthesis of arenesulfonyl fluorides from arylamine is developed with K2S2O5 and N-fluorobenzenesulfonimide (NFSI) as the sulfur dioxide surrogate and fluorine source, respectively. This method realizes the direct introduction of sulfonyl fluoride groups into arenes from abundant arylamines under transition-metal-free catalysis conditions, and features its mild and practical conditions and good functional group tolerance.

Palladium-Catalyzed Methylsulfonylation of Alkyl Halides Using Dimethyl Sulfite as SO2 Surrogate and Methyl Source.

A novel and efficient method for the synthesis of methyl sulfone derivatives via palladium-catalyzed methylsulfonylation of alkyl halides with dimethyl sulfite has been described. A variety of aryl and alkyl iodides underwent the sulfonylation smoothly to furnish methyl sulfites in moderate to excellent yields.

Short-term debt of the corporate sector and its impact on the stability of the financial system of Ukraine

The article deals with the economic essence of accounts payable. It is determined that in the process of deformations in the structure of business capital, it acquires the characteristics of a surrogate source of business financing, which in turn creates risks for the stability of Ukraine’s financial system. The authors describe the main trends in the dynamics and structure of accounts payable and define its impact on the growth of debt burden of non-financial corporations in Ukraine at the aggregate level. A comparison of the volume and growth rates of accounts payable in Ukraine and the EU countries is made, which allows to confirm the hypothesis of the introduction of a distorted model of business financing in Ukraine’s corporate sector. The authors point out that one of the reasons for the abnormally high debt dependence in the NFC sector at the aggregate level is the replacement of equity with other current liabilities (including financial loans from associated physical and legal entities), which allowed to establish such a flexible capital structure, which can help rapidly withdraw assets abroad in the event of macro-financial destabilization or other threats of capital loss related to the insecurity of property rights and the prevalence of fiscal voluntarism in Ukraine. The authors conclude that with the overload of balance sheets with short-term debts against the background of a significant reduction in equity leads to a rapid loss of financial stability. At the same time, under the influence of restrictions on activities and other concomitant barriers to doing business due to the global coronavirus pandemic, the financial depletion of the non-financial corporations sector could lead to a wave of corporate bankruptcies. It is concluded that under the influence of narrowing business access to capital in the financial market there is a rapid increase in lending to domestic business by nonresidents, which gives grounds to conclude that in this way domestic business lends itself, using funds previously withdrawn abroad. Further development of these trends not only can be a catalyst for financial imbalances at the level of individual enterprises, but can also provoke a crisis in the foreign exchange market. The authors substantiate that one of the ways to reduce the volume of current debt obligations is to assist the government in transforming the companies’ short-term liabilities into long-term ones. This can be done by converting the companies’ current liabilities into long-term bonds on a voluntary basis using simplified procedures for registration of their issue, and by registering current liabilities to suppliers (for goods and services) as long-term promissory notes.

КОРОТКОСТРОКОВА ЗАБОРГОВАНІСТЬ КОРПОРАТИВНОГО СЕКТОРА ТА ЇЇ ВПЛИВ НА СТАБІЛЬНІСТЬ ФІНАНСОВОЇ СИСТЕМИ УКРАЇНИ

The article deals with the economic essence of accounts payable. It is determined that in the process of deformations in the structure of business capital, it acquires the characteristics of a surrogate source of business financing, which in turn creates risks for the stability of Ukraine’s financial system. The authors describe the main trends in the dynamics and structure of accounts payable and define its impact on the growth of debt burden of non-financial corporations in Ukraine at the aggregate level. A comparison of the volume and growth rates of accounts payable in Ukraine and the EU countries is made, which allows to confirm the hypothesis of the introduction of a distorted model of business financing in Ukraine’s corporate sector. The authors point out that one of the reasons for the abnormally high debt dependence in the NFC sector at the aggregate level is the replacement of equity with other current liabilities (including financial loans from associated physical and legal entities), which allowed to establish such a flexible capital structure, which can help rapidly withdraw assets abroad in the event of macro-financial destabilization or other threats of capital loss related to the insecurity of property rights and the prevalence of fiscal voluntarism in Ukraine. The authors conclude that with the overload of balance sheets with short-term debts against the background of a significant reduction in equity leads to a rapid loss of financial stability. At the same time, under the influence of restrictions on activities and other concomitant barriers to doing business due to the global coronavirus pandemic, the financial depletion of the non-financial corporations sector could lead to a wave of corporate bankruptcies. It is concluded that under the influence of narrowing business access to capital in the financial market there is a rapid increase in lending to domestic business by nonresidents, which gives grounds to conclude that in this way domestic business lends itself, using funds previously withdrawn abroad. Further development of these trends not only can be a catalyst for financial imbalances at the level of individual enterprises, but can also provoke a crisis in the foreign exchange market. The authors substantiate that one of the ways to reduce the volume of current debt obligations is to assist the government in transforming the companies’ short-term liabilities into long-term ones. This can be done by converting the companies’ current liabilities into long-term bonds on a voluntary basis using simplified procedures for registration of their issue, and by registering current liabilities to suppliers (for goods and services) as long-term promissory notes.

Development of a multiplex mass spectrometry method for simultaneous quantification of urinary proteins related to respiratory health

Respiratory health of children is a health priority. Club cell protein (CC16) is an interesting biomarker of lung diseases and adverse effects towards the airway epithelium integrity. Osteopontin (OPN) and nuclear factor-kappa B (NF-κB) also play a role in respiratory health. The use of urine as biomarker source is useful in studies involving children but necessitates proper adjustment for physiological confounders influencing the urinary excretion, potentially characterized with beta-2-microglobulin (β2M), retinol binding protein 4 (RBP4) or myoglobin (MYO), as well as adjustment for possible renal dysfunction, characterized by human serum albumin (HSA). The simultaneous quantification of all these proteins in urine could facilitate children’s health monitoring. A multiple reaction monitoring method (MRM) was developed and validated for the relative quantification of the seven mentioned urinary proteins. A total of nine proteotypic peptides were selected and used for the relative quantification of the seven proteins. The MRM method was completely validated for all proteins and partially for OPN. LOQ’s ranged from 0.3 to 42.8 ng/ml, a good reproducibility and a good linearity were obtained across the analytical measurement range (r2 > 0.98). The method yielded varying correlations (r2 of 0.78, 0.71, 0.34 and 0.15 for CC16, β2M, RBP4 and HSA respectively) with available immunoassay data. It also allowed the identification and successful quantification of β2M and RBP4 as a protein candidate for adjustment of renal handling and dysfunction. All proteins were detected in the urine samples except for MYO and NF-κB. Our validated MRM-method is able to simultaneously quantify in urine biomarkers of airway epithelium integrity and biomarkers of variation in renal function and urinary dilution. This will allow to investigate further in future studies if urine can be used as a good surrogate source for biomarkers of airway epithelium integrity, and to understand the complex relationship between cause and effect in children’s respiratory health monitoring.

A near-exact analytic solution of progress variable and pdf for single-step Arrhenius chemistry

A new chemical reaction rate source term in the transport equation of a single progress variable is proposed and implications for premixed flame modelling are discussed. This surrogate source term approximates the Arrhenius one over a large range of activation energies and density ratios almost perfectly. An analytic, invertible flame profile and the corresponding 1D laminar flame pdf are derived. The laminar flame Eigenvalue is evaluated analytically for unity and non-unity Lewis number and compared to classical results. A method to evaluate the progress variable pdf from DNS data is introduced. It is based on regularized delta functions and a transformation of the DNS progress variable field with the inverse of the 1D laminar flame profile, which behaves like a signed distance function. The pdf factorizes into the flat flame pdf, a geometrical wrinkling factor and a correction factor accounting for changes in the inner flame structure. The pdfs of RANS-like filter volumes and their ingredients are evaluated from DNS datasets of statistically flat turbulent flames featuring different turbulence intensity levels. For all DNS cases the wrinkling and correction factors vary little with progress variable. The wrinkling factor rises with turbulence intensity. The pdf is similar to that of a 1D laminar flame pdf, scaled by the wrinkling factor. Opportunities for improvements to premixed turbulent flame modelling are discussed.

MTA Enhances the Potential of Adipose-Derived Mesenchymal Stem Cells for Dentin-Pulp Complex Regeneration.

The aim of the current study was to investigate the effects of mineral trioxide aggregate (MTA) on the proliferation and differentiation of human adipose-derived mesenchymal stem cells (Ad-MSCs) as a surrogate cell source in futuristic stem-cell-based endodontic therapies. Human Ad-MSCs and mesenchymal stem cells derived from bone marrow (BM-MSCs) were isolated from liposuction waste adipose tissue and femur, respectively, and the effects of MTA-conditioned media on their viability, mineralization potential, and osteo/odontogenic differentiation capacity were subsequently evaluated. Alkaline phosphatase (ALP) activity, quantitative alizarin red S staining, and quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analyses were performed to investigate and compare the osteo/odontogenic induction potential of MTA on the Ad/BM-MSCs. The results of cytotoxicity assay revealed that at different concentrations, MTA-conditioned medium was not only biocompatible toward both cell types, but also capable of promoting cell proliferation. ALP activity assay showed that 0.2 mg/mL was the optimal concentration of MTA-conditioned medium for osteo/odontogenic induction in Ad/BM-MSCs. The expression of osteo/odontogenic gene markers was increased in Ad/BM-MSCs treated with 0.2 mg/mL MTA-conditioned media. Our results indicated that MTA can efficiently enhance the osteo/odontogenic potential of Ad-MSCs, and thus they can be considered as a better cell source for dentin–pulp complex regeneration. However, further investigations are required to test these potentials in animal models.

Consolidated plasmid Design for Stabilized Heterologous Production of the complex natural product Siderophore Yersiniabactin.

Yersiniabactin (Ybt) is a hybrid polyketide-nonribosomal complex natural product also known as a siderophore for its iron chelation properties. The native producer of Ybt, Yersinia pestis, is a priority pathogen responsible for the plague in which the siderophore properties of Ybt are used to sequester iron and other metal species upon host infection. Alternatively, the high metal binding properties of Ybt enable a plethora of potentially valuable applications benefiting from metal remediation and/or recovery. For these applications, a surrogate production source is highly preferred relative to the pathogenic native host. In this work, we present a modification to the heterologous Escherichia coli production system established for Ybt biosynthesis. In particular, the multiple plasmids originally used to express the genetic pathway required for Ybt biosynthesis were consolidated to a single, copy-amplifiable plasmid. In so doing, plasmid stability was improved from ~30% to ≥80% while production values maintained at 20-30% of the original system, which resulted in titers of 0.5-3 mg/L from shake flask vessels.

Insight into decomposition of formic acid to syngas required for Rh-catalyzed hydroformylation of olefins

Formic acid (FA) is one kind of important bulk chemicals, which is recognized as a sustainable and eco-friendly energy carrier to transport H2 via dehydrogenation or CO via decarbonylation. Expectantly, FA upon decomposition into H2 and CO could be used as the syngas alternative for hydroformylation. In this paper, the behaviors of FA to release H2 as well as CO following the distinct pathways were carefully investigated for the first time, and then established a new hydroformylation protocol free of syngas. It was found that the atmospheric hydroformylation of olefins with formic acid (FA) as syngas alternative was smoothly fulfilled over Xantphos (L1) modified Rh-catalyst under mild conditions (80 °C, Rh concentration 1 mol %, 14 h), resulting in >90% conversion of the olefins along with the high selectivity to the target aldehydes (>93%). By using FA as syngas source, the side-reaction of olefin-hydrogenation was greatly depressed. The in situ FT-IR and the high-pressure 1H NMR spectroscopic analyses were applied to reveal how FA behaves dually as CO surrogate and hydrogen source over L1-Rh(acac)(CO)2 catalytic system, based on which the deeply insight into the catalytic mechanism of hydroformylation of olefins with FA as syngas alternative was offered.

Testing and optimization of 3D-printed volumetric diffusor arrays for attenuation of blast noise

3D-printed volumetric diffusing array structures, composed of many arbitrarily shaped pillars in an optimized pattern, have previously been shown to be very effective for blast noise attenuation in a scale model experiment (Ochi et al., 2019). This work expands upon previous progress by investigating innovative optimization schemes for the array designs, and further testing these optimized arrays in scale model experiments with a spark gap generator operating as a surrogate blast noise source. Properties of the propagated signal, including directivity, duration, and spectral characteristics, are discussed, as well as how these properties depend on the choice of volumetric diffusor. Finally, the propagated waveform, spectra, and effective attenuation predicted using 2D-FDTD simulations are compared with the results of the experiment as a method of testing the validity of the simulations.