Matrix Types Research Articles

Audit on Going Concern in the Context of an Institutional Approach

In the conditions of uncertainty, going concern auditing (GCA) or auditing of continuity of operations is an effective tool for preventing adverse effects and consequences of disruption of the stable functioning of the organization and at the same time a possible situation of systemic defaults and non-payments associated with the retirement or disposal of one of the counterparties in the payment and settlement chain. The aim of this article is to substantiate the nature and examine the issues of the degree of implementation into practice and the completeness of disclosure of all the functions of going concern auditing, depending on the characteristics of the national economy and the institutional environment. The research is based on a dichotomous approach, in which two types of institutional matrix are distinguished: the Xmatrix and the Y-matrix. At the same time, all the participants in the auditing process are divided into three groups: the audited person or entity, the auditor (auditing organization or individual entrepreneur/sole proprietor), the regulators of auditing activities. Various scenarios of their behavior depending on the institutional matrix are described in this article. The purpose of the study is to develop the theoretical foundations of going concern auditing in the context of ensuring that its functional capabilities meet and comply with the established conditions and traditions of the host institutional environment. The study was carried out on the example of the Republic of Belarus. The research used scientific methods of theoretical (analysis and synthesis, grouping, generalization, systematization) and empirical (selective observation, comparison, case study) levels. The significance of the conducted research is in clarifying the methodological foundations of the going concern auditing based on the institutional approach, which made it possible to take into account and explain the impact on the current practice of the features of a specific institutional model and develop practical recommendations regarding the completeness of the functional capabilities of the business on going audit in relation to the features of the national economic system.

Significance of polymer matrix on the resistive switching performance of lead-free double perovskite nanocomposite based flexible memory device

Polymer based resistive switching (RS) is one of the most rapidly growing memory technology that is being developed for next-generation flexible/wearable devices. In this work, we have chosen two types of host polymer matrix to support the Pb-free Cs2AgBiBr6 double perovskite nanofillers. Selection of poly(methyl methacrylate) (PMMA) and polyethylene oxide (PEO) is based on their nature of insulating and ionic conductivity respectively. To eliminate the dominance of electrode on (RS), Au and ITO were chosen as top and bottom electrode respectively. The PEO based device with or without nanofiller did not show significant differences in device performance. On the contrary, substantial impact of nanofiller in PMMA based devices could be observed. Interestingly, with the concentration of 2% Cs2AgBiBr6 nanofillers in both the polymer matrix, the devices exhibited adequate bipolar memory switching behavior. However, the PMMA composite device (with 2% nanofiller) exhibited excellent RS properties such as low operating voltage, high current ON/OFF ratio, long endurance and retention in both normal and bending mode. Low value of ON/OFF ratio in PEO composite device could be attributed to higher conductivity of PEO polymer matrix that result into high current in the OFF state. Finally, the indispensable results in the PMMA nanocomposite based flexible device was hypothesized by using energy band diagram on the basis of charge trapping/de-trapping inside the functional matrix and pave the way for the development of next-generation flexible electronics.

A novel damage evaluation of CFRPs under mode-I loading by using multi-instrument structural health monitoring methods

Mode-I fracture toughness test provides valuable information in the thickness direction of fiber reinforced polymer matrix composites. However, damage propagation under mode-I loading is dependent on the configuration of reinforcing material of the laminate. Understanding the damage types and their growth rate in mode-I fracture toughness test is a vital factor to obtain material allowable for safe design. In this study, mode-I tests are conducted on unidirectional, and twill woven carbon fiber reinforced polymer composite laminates. A new approach is proposed to interpret passive infrared thermography results based on correlating acoustic emission and thermography results in time whereby thermal activities can be classified into two main groups corresponding to matrix and fiber dominant failure types. It is demonstrated that matrix and fiber dominant failures lead to thermal activities with line-wise and point-wise form, respectively. Results show that four different damage types can be seen for mode-I fracture of both laminates. The temporal observations during thermoelastic cooling of the materials show that twill woven laminate releases relatively higher energies due to matrix dominant damage developments which means this configuration type is more prone for delamination failures.

The cell origins of foam cell and lipid metabolism regulated by mechanical stress in atherosclerosis.

Atherosclerosis is an inflammatory disease initiated by endothelial activation, in which lipoprotein, cholesterol, extracellular matrix, and various types of immune and non-immune cells are accumulated and formed into plaques on the arterial wall suffering from disturbed flow, characterized by low and oscillating shear stress. Foam cells are a major cellular component in atherosclerotic plaques, which play an indispensable role in the occurrence, development and rupture of atherosclerotic plaques. It was previously believed that foam cells were derived from macrophages or smooth muscle cells, but recent studies have suggested that there are other sources of foam cells. Many studies have found that the distribution of atherosclerotic plaques is not random but distributed at the bend and bifurcation of the arterial tree. The development and rupture of atherosclerotic plaque are affected by mechanical stress. In this review, we reviewed the advances in foam cell formation in atherosclerosis and the regulation of atherosclerotic plaque and lipid metabolism by mechanical forces. These findings provide new clues for investigating the mechanisms of atherosclerotic plaque formation and progression.

DART-MS Facilitated Quantification of Cannabinoids in Complex Edible Matrices-Focus on Chocolates and Gelatin-Based Fruit Candies.

Traditional methods for detecting and quantifying cannabinoids in Cannabis sativa materials are most often chromatography-based, and they generally require extensive sample preparation protocols to render materials into a form that can be injected into the systems without the risk of contaminating or damaging the equipment. This challenge is amplified when interrogating the increasingly broad range of matrix types that cannabinoids are infused within, such as edibles that also contain sugars, fats, lipids, and carbohydrates. The requisite application of highly nuanced methods that must be developed for each matrix type is, in addition to being resource-intensive and time-consuming, highly impractical and unsustainable for crime laboratories endeavoring to perform such analyses in a routine manner, since they are often under-resourced while typically also confronting sample testing backlogs. A key to resolving this issue is to identify an analysis approach that avoids the requirement for nuanced method development by being applicable to a broader range of matrix types. Ambient ionization mass spectrometry (AIMS) methods have shown great promise in their ability to rapidly interrogate samples. Therefore, this study focused on developing validated protocols using AIMS (specifically, direct analysis in real time-high-resolution mass spectrometry, or DART-HRMS) to detect and quantify Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) in edible matrices. Calibration curves were developed using deuterated counterparts of THC and CBD as internal standards. Following the use of high cannabinoid recovery rate extraction protocols for chocolates and gelatin-based fruit candies or "gummies", the DART-HRMS approach was applied to quantify cannabinoid levels in commercially available cannabinoid-infused candies, yielding results similar to those reported on the product labels. Importantly, the developed method circumvented challenges encountered using traditional approaches. As the Cannabis field continues to evolve and new matrix types emerge on the market, the DART-HRMS detection and quantification protocols can be readily applied without the need for major procedural adaptations.

Abstract 2758: Expanding PRISM high-throughput screening capabilities to other modalities

Abstract PRISM, a high-throughput drug screening platform, has been used extensively to profile DMSO-soluble compounds, including nearly all commercially available FDA-approved small molecule drugs, in pools of cancer cell lines. In addition to these highly-optimized compounds, novel small-molecule libraries comprising tens of thousands of compounds have been screened through collaborative partnerships. While PRISM has been highly effective in discovering new therapeutic targets and classes via libraries of this nature, we have not yet explored screening aqueous molecules at scale, such as antibodies, antibody-drug conjugates (ADCs), cytokines, and other biologics. There is also untapped potential for the further development of PRISM-based assays utilizing more physiologically relevant assay conditions to gain new insights into cancer biology and highlight more clinically relevant targets. Specifically, the incorporation of environmental cues such as media nutrients, extracellular matrix, and other non-cancer cell types can have a drastic impact on cancer cell state, and thus cancer cell responses to therapy. For example, PRISM pools grown as 3D spheroids, compared to 2D mono-layers, reveal models showing increased sensitivity to mutant KRAS inhibition. Similarly, the addition of immune effector cells, via co-culture methods, to the PRISM platform will enable identification of key mechanisms involved in antibody-dependent cellular cytotoxicity and measurement of immunotherapeutic-relevant phenotypes at an unprecedented scale. This coupling of aqueous screening, with the addition of relevant tumor-microenvironmental cues may help identify therapies more destined to succeed in the clinic, and delineate novel mechanisms involved in cancer cell-state that underpin the many clinical challenges we face in curing cancer. Citation Format: Jacob Smigiel, Jillian Eskra, Antonella Masciotti, Aydin Golabi, Blanche Ip, Melissa Ronan, Matthew G. Rees, Jennifer Roth. Expanding PRISM high-throughput screening capabilities to other modalities [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2758.

Nonlinear micromechanical modeling of fully coupled piezo-elastic composite under large deformation and high electric field

This paper presents mathematical modeling and predictions of effective nonlinear electro-mechanical behavior of piezoelectric materials under large deformation and high electric field. The heterogeneous inclusion problem is extended to investigate the fields dependent electro-elastic behaviors under high fields. The associated strain field dependent Green tensors are introduced. The field dependent interaction tensors, related to Eshelby’s tensors, are explicitly formulated and used to derive micromechanical models based on the Mori–Tanaka approach and the self-consistent model. Due to electric-strain field dependence nonlinear algebraic tensors equations are resulted. Iterative incremental schemes based on the Newton–Raphson algorithm are elaborated and explicit semi-analytical formulations of electric-strain field dependent effective electro-elastic moduli of piezoelectric multi-phase composites are obtained for various inclusion types. Strain and electric field’s effects on effective properties can be analyzed for various electro-elastic composites. Numerical results of field dependent effective electro-mechanical properties are given for several inclusion’s volume fraction and shapes as well as types of matrix and inclusions phases.

The Vault Complex Is Significantly Involved in Therapeutic Responsiveness of Endocrine Tumors and Linked to Autophagy under Chemotherapeutic Conditions

Cancers display dynamic interactions with their complex microenvironments that influence tumor growth, invasiveness, and immune evasion, thereby also influencing potential resistance to therapeutic treatments. The tumor microenvironment (TME) includes cells of the immune system, the extracellular matrix, blood vessels, and other cell types, such as fibroblasts or adipocytes. Various cell types forming this TME secrete exosomes, and molecules thereby released into the TME have been shown to be important mediators of cellular communication and interplay. Specific stressors in the TME, such as hypoxia, starvation, inflammation, and damage, can furthermore induce autophagy, a fundamental cellular process that degrades and recycles molecules and subcellular components, and recently it has been demonstrated that the small non-coding vault RNA1-1 plays a role as a regulator of autophagy and the coordinated lysosomal expression and regulation (CLEAR) network. Here, we demonstrate for the first time that intra-tumoral damage following effective therapeutic treatment is linked to specific intracellular synthesis and subsequent exosomal release of vault RNAs in endocrine tumors in vitro and in vivo. While we observed a subsequent upregulation of autophagic markers under classical chemotherapeutic conditions, a downregulation of autophagy could be detected under conditions strongly involving inflammatory cascades.

Determination of new glucocorticoid called clobetasol acetate in cosmetics by ultra performance liquid chromatography-tandem mass spectrometry

At present, new prohibited substances are becoming more common illegal additions in cosmetics. Clobetasol acetate is a new glucocorticoid, which is not covered in the current national standards and is a homologue of clobetasol propionate. A method was established for the determination of clobetasol acetate as a new glucocorticoid (GC) in cosmetics by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Five common cosmetic matrices were suitable for this new method: creams, gels, clay masks, masks and lotions. Four pretreatment methods were compared: direct extraction by acetonitrile, PRiME pass-through column purification, solid-phase extraction (SPE) purification, and QuEChERS purification. Further, the effects of different extraction efficiencies of the target compound, such as extraction solvents and extraction time, were investigated. The MS parameters, such as ion mode, cone voltage and collision energy of ion pairs of the target compound, were optimized. The chromatographic separation conditions and response intensities of the target compound in different mobile phases were compared. Based on the experimental results, the optimal extraction method was determined to be direct extraction, wherein the samples were vortex dispersed with acetonitrile, ultrasonic extraction over 30 min and filtered by a 0.22 μm organic millipore filter, and then the samples were detected by UPLC-MS/MS. The concentrated extracts were separated on a Waters CORTECS C18 column (150 mm×2.1 mm, 2.7 μm), where the water and acetonitrile were used as the mobile phases for gradient elution. The target compound was detected with the multiple reaction monitoring (MRM) mode under electrospray ionization and positive ion scanning (ESI+). Quantitative analysis was performed by matrix matching standard curve. Under the optimum conditions, the target compound had good linear fitting in the range of 0.9-37 μg/L. The linear correlation coefficient (R2) was greater than 0.99, the limit of quantification (LOQ) of the method was 0.09 μg/g and the limit of detection (LOD) was 0.03 μg/g for these five different cosmetic matrices. The recovery test was conducted under three spiked levels: 1, 2 and 10 times of LOQ. The recoveries of the tested substance were between 83.2% and 103.2% in these five cosmetic matrices, and the relative standard deviations (RSDs, n=6) were between 1.4% and 5.6%. This method was used to screen cosmetic samples of different matrix types, and a total of five positive samples were found, in which the content range of clobetasol acetate was from 1.1 to 48.1 μg/g. In conclusion, the method is simple, sensitive and reliable, and is suitable for high-throughput qualitative and quantitative screening, and the analysis of cosmetics with different matrix types. Moreover, the method provides crucial technical support and a theoretical basis for the establishment of feasible detection standards for clobetasol acetate in China, as well as for the control of the compound in cosmetics. This method has important practical significance to implement management measures of illegal additions in cosmetics.

Hg Content in EU and Non-EU Processed Meat and Fish Foods

Mercury is one of the most dangerous toxic elements. Fresh food is the primary source of Hg exposure for humans. However, since processed foods are also a fundamental part of the food system, continuous monitoring of this contaminant in processed products is necessary to safeguard consumer health. The purpose of this study was to determine the Hg content using a direct mercury analyzer (DMA-80) in different processed food products (beef, pork, poultry, shellfish, and fish species) of EU and non-EU origin purchased in supermarkets and ethnic food shops in Messina (Italy). The results obtained were variable and correlated with the different types of food matrix. Low mercury levels were obtained for beef, pork, and poultry products, ranging from <LOQ for most samples to 3.727 µg/Kg. Higher concentrations were, however, obtained for fish species (9.249–290.211 µg/Kg). The mercury content was below the maximum levels specified in Regulation No 1881/2006 as amended. Percentage of Tolerable Weekly Intake (TWI) values of total Hg were evaluated in accordance with the European Food Safety Authority (EFSA). The results showed that some of the pelagic species of the genus Thunnus thynnus exceeded the TWI values.

Vascular mechanotransduction.

This review aims to survey the current state of mechanotransduction in vascular smooth muscle cells (VSMCs) and endothelial cells (ECs), including their sensing of mechanical stimuli and transduction of mechanical signals that result in the acute functional modulation and longer-term transcriptomic and epigenetic regulation of blood vessels. The mechanosensors discussed include ion channels, plasma membrane-associated structures and receptors, and junction proteins. The mechanosignaling pathways presented include the cytoskeleton, integrins, extracellular matrix, and intracellular signaling molecules. These are followed by discussions on mechanical regulation of transcriptome and epigenetics, relevance of mechanotransduction to health and disease, and interactions between VSMCs and ECs. Throughout this review, we offer suggestions for specific topics that require further understanding. In the closing section on conclusions and perspectives, we summarize what is known and point out the need to treat the vasculature as a system, including not only VSMCs and ECs but also the extracellular matrix and other types of cells such as resident macrophages and pericytes, so that we can fully understand the physiology and pathophysiology of the blood vessel as a whole, thus enhancing the comprehension, diagnosis, treatment, and prevention of vascular diseases.

Optical enhancement of highly efficient organic-inorganic oxyfluoride red phosphors via the cation co-doping strategy.

Herein, a new organic cationic matrix [N(CH3)4]3MoO3F3 suitable for Mn4+ doping was constructed. Due to the large steric hindrance of N[CH3]4+ (TMA), charge compensation defects can be effectively prevented in the heterovalent Mn4+-doping process, and a high IQE (91.05%) was obtained. Through the cation co-doping strategy, Mg2+/Zn2+/Li+ cations were introduced into the Mo6+ cationic site, which improved the crystallinity of the matrix and reduced energy losses, so as to improve luminescence intensity, QE, thermal stability, water stability and other spectral properties. Meanwhile, [N(CH3)4]2TiF6:Mn4+ phosphors with the same TMA organic cation and equivalent Mn4+ doping were synthesized for comparison, and the effects of the Mg2+ cation co-doping strategy on the spectral properties of phosphors with different matrix types (fluoride/oxyfluoride) and substitution types (equivalent/non-equivalent) were analyzed. These findings provide the basis for the preparation of new luminescent materials. Furthermore, according to the optical properties exhibited by these phosphors, they are packaged into WLED devices with excellent photoelectric properties, which are suitable for indoor lighting and display fields.

Determination of polyfluoroalkyl substances in cosmetic products using dispersed liquid-liquid extraction coupled with UHPLC-MS/MS.

Human exposure to polyfluoroalkyl substances (PFASs) via cosmetics has been of increasing concern due to the tremendous detrimental health impacts of PFASs. Developing an effective method for extracting and determining PFASs in cosmetics is crucial in accurately assessing their corresponding human exposure risk. Herein, this study developed a new sample pre-treatment method to address the challenges posed by the variety and complexity of cosmetic matrices. Seventeen PFASs in cosmetic products, including 9 perfluoro carboxylic acids and 8 perfluorosulfonic acids, were simultaneously determined using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The whole pre-treatment process can be divided into three steps. In step 1, cosmetics with diverse matrix types can be effectively dispersed during extraction by using saturated sodium chloride-acetonitrile and saturated sodium chloride-tetrahydrofuran as extraction solvents. In step 2, the pre-purification step employs a potassium ferrocyanide-zinc acetate co-precipitant to remove high molecular weight interferents from the extraction solution, thereby enhancing the efficiency of solid-phase extraction (SPE). In step 3, WAX-SPE is utilized to further eliminate interferents from the extraction solution while concentrating the analytes, meeting the trace analysis requirements for PFASs in cosmetics. The method detection limits were 0.09-0.26 ng g-1. The recoveries ranged from 70.1% to 114.7%, with relative standard deviations in the range of 2.0-19.1%. The method was applied to cosmetic samples in the Guangzhou market, and the total concentration of PFASs ranged from 0 to 10.8 ng g-1. This method has strong anti-interference ability, good applicability, high sensitivity, and good reproducibility, making it suitable for the analysis and detection of perfluorinated acids in cosmetic samples. It provides technical support for cosmetics safety regulation.

The role of landscape in shaping bird community and implications for landscape management at Nanjing Lukou International Airport.

Understanding the patterns of bird diversity and its driving force is necessary for bird strike prevention. In this study, we investigated the effects of landscape on phylogenetic and functional diversity of bird communities at Nanjing Lukou International Airport (NLIA). Bird identifications and counting of individuals were carried out from November 2017 to October 2019. Based on the land-cover data, the landscape was divided into four main types, including farmlands, woodlands, wetlands, and urban areas. Bird phylogenetic and functional diversity were strongly affected by landscape matrix types. Species richness and Faith's phylogenetic distance were highest in woodlands, while mean pairwise distance (MPD), mean nearest-taxon distance (MNTD), and functional dispersion (FDis) were highest in wetlands. Based on the feeding behavior, carnivorous birds had the lowest species richness but had the highest FDis, which implied that carnivorous birds occupied most niches at the NLIA. Moreover, bird assemblages exhibited phylogenetic and functional clustering in the four kinds of landscapes. A variety of landscape attributes had significant effects on species diversity, phylogenetic and functional diversity. Landscape-scale factors played an important role in the shaping of bird communities around NLIA. Our results suggest that landscape management surrounding airports can provide new approaches for policymakers to mitigate wildlife strikes.

Robustness of LabSOCS calculating Ge detector efficiency for the measurement of radionuclides

The LabSOCS software is one of the main simulation codes employed to calculate the full-energy peak efficiency (FEPE) for the measurements of radionuclides by gamma-ray spectrometry. The validity of LabSOCS has not previously been evaluated for a large variety of matrixes, geometry types, and energies. This study aims to analyze in depth the LabSOCS FEPE robustness comparing the LabSOCS and experimental FEPEs by using three coaxial Ge detectors for a wide range of samples, varying the matrix composition, counting geometry (thickness (h) for cylindrical geometry), gamma emission energy (Eγ), and bulk density (ρ). The FEPE averages and variances calculated for numerous matrix types prepared using gamma cocktails were statistically comparable for a wide Eγ range (from 46 keV (210Pb) to 1836 keV (88Y)). To test the accuracy of the LabSOCS FEPEs varying h (6–50 mm), four certified samples containing only natural radionuclides were used. The 234, 228Th, 228, 226Ra, 210Pb and 40K activities were determined for each h, obtaining |zscore| < 2 in general. This also proves the good reproducibility of LabSOCS calculating activity concentrations. The LabSOCS FEPE robustness was also tested for a wide ρ range (1.3–2.8 g cm−3) mixing a sediment sample with Pb(NO3)2 for h = 50 mm. The 210Pb and 234Th contained in each mixture were determined, achieving all |zscore| < 2. Furthermore, the ability of LabSOCS to correct self-attenuation effects was checked to be wider than when other correction models are applied.

Tests to Optimize the Multiplication of Oleander (Apocynaceae) in Soil and Water Matrices

The vegetative propagation of oleander (Apocynaceae), an ornamental plant for aesthetic use, is based on the technique of cuttings. This study focused on optimizing this multiplication. To do this, two types of matrix were used, in particular soil and water. Cuttings were taken from oleander plants and the apical, middle and basal parts of the stems were cultured in water and soil. The results showed that after 3 weeks the cuttings, thus installed, constitute the seat of the formation of the roots and the new-formation of the buds. The characteristics of these cuttings were established with cuttings from plantations obtained by artificial regeneration. Thus, on a stem twig, we distinguished basal, middle and apical cuttings. Recovery time varies from one category of cuttings to another, but the highest recovery rate (86.7%) was obtained with middle cuttings. The results obtained are of paramount importance in the success of the rapid multiplication of this ornamental species highly prized by urban florists in Niger.

Persistence and transfer of Tulane virus in a microgreen cultivation system

Microgreens are niche salad greens which have increased in popularity among consumers in recent years. Due to similarities with sprouts and leafy greens—both attributed to numerous foodborne disease outbreaks—characterization of the food safety risks associated with microgreen production is warranted. The present study aimed to determine the fate and persistence of a human norovirus (HuNoV) surrogate, Tulane virus (TV), within a microgreen production system. Initially, the persistence of TV in two types of microgreen soil-free cultivation matrix (SFCM)—BioStrate® (biostrate) and peat—was determined. On day 0, water containing 7.6 log PFU of TV was applied to SFCM in growing trays, and the trays were maintained under microgreen growth conditions. TV persisted throughout the 10-day observation in biostrate and peat with overall reductions of 3.04 and 1.76 log plaque forming units (PFU) per tray, respectively. Subsequently, the transfer of TV to microgreen edible tissue was determined when planted on contaminated SFCM. Trays containing each type of SFCM were pre-inoculated with 7.6 log PFU of TV and equally divided into two areas. On day 0, sunflower (SF) or pea shoot (PS) seeds were planted on one-half of each tray, while the other half was left unplanted to serve as a control. The microgreens were harvested on day 10, and SFCM samples were collected from planted and unplanted areas of each tray. No TV were detected from the edible portion of either type of microgreen, yet TV were still present in the SFCM. TV concentrations were significantly lower in the root-containing planted area compared with the unplanted area for both biostrate (P = 0.0282) and peat (P = 0.0054). The mean differences of TV concentrations between unplanted and planted areas were 1.22 and 0.51 log PFU/g for biostrate and peat, respectively. In a subsequent investigation, TV transfer from day 7 inoculated SFCM to microgreens edible portion was not detected either. Overall, this study characterized the viral risk in a microgreen production system, which will help to understand the potential food safety risk related to HuNoV and to develop preventive measures.

A Human Bone Marrow 3D Model to Investigate the Dynamics and Interactions Between Resident Cells in Physiological or Tumoral Contexts.

The medullary niche is a complex ecosystem that is essential to maintain homeostasis for resident cells. Indeed, the bone marrow, which includes a complex extracellular matrix and various cell types, such as mesenchymal stem cells, osteoblasts, and endothelial cells, is deeply involved in hematopoietic stem cell regulation through direct cell-cell interactions, as well as cytokine production. To closely mimic this in vivo structure and conduct experiments reflecting the responses of the human bone marrow, several 3D models have been created based on biomaterials, relying primarily on primary stromal cells. Here, a protocol is described to obtain a minimal and standardized system that is easy to set up and provides features of bone marrow-like structure, which combines different cell populations including endothelial cells, and reflects the heterogeneity of in vivo bone marrow tissue. This 3D bone marrow-like structure-assembled using calcium phosphate-based particles and human cell lines, representative of the bone marrow microenvironment-allows the monitoring of a wide variety of biological processes by combining or replacing different primary cell populations within the system. The final 3D structures can then either be harvested for image analysis after fixation, paraffin-embedding, and histological/immunohistochemical staining for cell localization within the system, or dissociated to collect each cellular component for molecular or functional characterization.

Estimation and order selection for multivariate exponential power mixture models

Finite mixture model is a promising statistical model in investigating the heterogeneity of population. For multivariate non-Gaussian density estimation and approximation, in this paper, we consider to use multivariate exponential power mixture models. We propose the penalized-likelihood method with a generalized EM algorithm to estimate locations, scale matrices, shape parameters, and mixing probabilities. Order selection is achieved simultaneously. Properties of the estimated order have been derived. Although we mainly focus on the unconstrained scale matrix type in multivariate exponential power mixture models, three more parsimonious types of scale matrix have also been considered. Performance based on simulation and real data analysis implies the parsimony of the exponential power mixture models, and verifies the consistency of order selection.

Color-Tunable Binary Copolymers Manipulated by Intramolecular Aggregation and Hydrogen Bonding.

Construction of color-tunable luminescent polymeric materials with enhanced emission intensity and room-temperature phosphorescence (RTP) performance regulated by a single chromophore component is highly desirable in the scope of photoluminescent materials. Herein, a set of binary copolymers were facilely synthesized using free radical polymerization by selecting different types of polymer matrix and N-substituted naphthalimides (NPA) as chromophores. Surprisingly, the fluorescence emission of copolymers could be remarkably enhanced, because of the intramolecular aggregation of NPA manipulated by a single polymer chain in both solution and solid state. Moreover, RTP signals of binary copolymers were all clearly observed in the air without any processing procedure, because of the embedding of phosphors into hydrogen bonding networks after copolymerization with vinyl-based acrylamide monomers. Taking advantages of the synergistic effect of copolymerization-induced aggregation and copolymerization-induced rigidification to promote optical performance, UV stimulus-responsive luminescent polymer films with processability, flexibility, and adjustable emission wavelength were simply prepared using a drop-casting method in large scale, the setting of which is the basis for application in the fields of organic optoelectronics, information security, and bioimaging/sensing.