Study of dead time estimation method based on pulse interval distribution.

In nuclear radiation detection, some measured radiation counts are lost due to dead time. Estimation of dead time is necessary to restore the counting information in quantitative analysis. This study aims to propose a method for estimating dead time at high counting rate. First of all, a measurement system of pulse interval distribution was used to estimate the true input counting rate of the detection system and implemented in FPGA. Then, a digital pole-zero cancellation technique was introduced in the measurement system to decrease the decay time constant of pulse. This was aimed at mitigating the impact of pile-up on the pulse interval distribution spectrum, especially at high counting rate. The feasibility of this measurement system at high counting rate was verified by the experimental platform of EDXRF. The dead time was calculated using the measured counting rate and the estimated true input counting rate. The accuracy of the dead time relies on the precision of the estimated true count rate. When the counting rate reaches 600 kCPS, the relative error between the theoretical counting rate and the estimated true input counting rate is less than 5%.

Association of apolipoprotein levels with all-cause and cardiovascular mortality.

AIMS: Research has shown that apolipoproteins (Apos) are potential indicators of heart health and death. We investigated the associations of apolipoprotein levels with all-cause and cardiovascular mortality. METHODS: We systematically searched the Cochrane Library, PubMed and Web of Science for English-language studies up to November 28, 2022. We used Stata 17.0 to summarize the estimated effects with 95% confidence intervals (CIs). We also conducted subgroup analyses according to study location, year of publication, individual age, follow-up years, and sample size. Moreover, we performed a sensitivity analysis to evaluate bias in our study. RESULTS: This study included 23 studies with 152854 individuals in total. The level of ApoA was negatively related to cardiovascular mortality (OR = 0.69, 95% CI = 0.52-0.93). An increased ratio of ApoB/A1 was a risk factor for cardiovascular mortality (OR = 2.13, 95% CI = 1.48-3.07) and all-cause mortality (OR = 2.05, 95% CI = 1.52-2.77). The level of ApoB was positively related to cardiovascular mortality (OR = 1.12, 95% CI = 0.85-1.47), but the difference was not statistically significant. However, the associations between ApoB or ApoA1 and all-cause mortality were not obvious. Our subgroup analysis showed that the location, year of publication, individual age, and follow-up years of the studies affected the heterogeneity of our study to varying degrees. The sensitivity analysis showed that our results were almost robust, apart from excluding the article by Nomikos (OR = 0.77, 95% CI = 0.65-0.92) and Zeng (OR = 0.77, 95% CI = 0.65-0.91), when investigating the relationship between ApoA1 and all-cause mortality. CONCLUSION: In this study, we found that apolipoprotein levels were linked to cardiovascular and all-cause mortality. Our study strengthens the evidence on the association between the level of apolipoproteins and cardiac health and may provide ideas for regulating the level of apolipoproteins to promote public health.

This study supports the association between apolipoproteins and cardiac health by conducting an analysis of the impact of ApoA1, ApoB2 and the ratio of ApoB/A1 on cardiovascular mortality and all-cause mortality. These findings may provide some ideas for promoting public health.

Carboxymethyl chitosan-based hydrogel-Janus nanofiber scaffolds with unidirectional storage-drainage of biofluid for accelerating full-thickness wound healing.

Self-pumping wound scaffolds designed for directional biofluid transport are extensively investigated. They efficiently extract excessive biofluids from wounds, while maintaining an optimally humid wound environment, thus facilitating rapid wound healing. However, the existing designed scaffolds are insufficiently focused on stimulating the hydrophobic layer at the wound site, thereby exacerbating inflammation and impeding the wound healing process. Herein, we engineered and fabricated a hydrophilic-hydrophobic-hydrophilic sandwich-structured hydrogel-Janus nanofiber scaffold (NFS) employing a Layer-by-Layer (LbL) method. This scaffold comprises a hydrophilic carboxymethyl chitosan/silver (CMCS-Ag) hydrogel component in conjunction with a poly(caprolactone)/poly(caprolactone)-poly(citric acid)-co-ε-polylysine (PCL/PCL-PCE) Janus NFS. It is noteworthy that the hydrogel-Janus nanofiber scaffold not only demonstrates outstanding water absorption (202.2 %) and unidirectional biofluid transport capability but also possesses high breathability (308.663 m3/m2 h kPa), appropriate pore size (6.7-7.5 µm), excellent tensile performance (270 ± 10 %), and superior mechanical strength (26.36 ± 1.77 MPa). Moreover, in vitro experimentation has convincingly demonstrated the impeccable biocompatibility of hydrogel-Janus NFS. The inherent dual-antibacterial properties in CMCS-Ag and PCE significantly augment fibroblast proliferation and migration. In vivo studies further underscore its capability to expedite wound healing by absorption and expulsion of wound exudates, thereby fostering collagen deposition and vascularization. As such, this work potentially provides fresh insights into the design and fabrication of multifunctional biomimetic scaffolds, holding immense potential in the medical field for efficient wound healing.

Association between exposure to per- and polyfluoroalkyl substances and levels of lipid profile based on human studies.

Epidemiological evidence suggests that exposure to per- and polyfluoroalkyl substances (PFAS) is associated with lipid profile levels, but with inconsistent conclusions from different studies. The aim of this study was to conduct a meta-analysis of the relationship between PFAS exposure and lipid profile levels based on population-based epidemiological studies. Embase, PubMed, Ovid database, The Cochrane Library and Web of Science database were used to search appropriate studies (before September 6, 2022) on the correlation between PFAS exposure and lipid profile levels. ß value, odd ratio (OR) and 95 % confidence intervals (CIs) were extracted from studies. In this study, we found that higher low-density lipoprotein (LDL) levels were associated with exposure to perfluoroundecanoic acid (PFUnDA) (ß value=0.13, 95 % CIs: 0.02, 0.24) and perfluorooctane sulfonic acid (PFOS) (ß value=0.13, 95 % CIs: 0.04, 0.21). PFOA, PFOS and PFNA exposure were significantly related to the higher levels of total cholesterol (TC) with the pooled effect estimates of 0.08 (95 % CI: 0.02, 0.14), 0.13 (95 % CI: 0.05, 0.21) and 0.14 (95 % CI: 0.08, 0.20) respectively. In sum, our results identified that PFOA, PFOS, PFNA and PFUnDA were the most important risk factors for abnormal levels of lipid profile, indicating that we should prevent cerebrovascular disease by reducing and controlling PFAS exposure.

Regulation of photosynthetic and hemolytic activity of Phaeocystis globosa under different light spectra.

Phaeocystis globosa frequently proliferates in eutrophic waters and forms ichthyotoxic algal blooms that cause massive fish mortalities in marine ecosystems. One of the ichthyotoxic metabolites was identified as the glycolipid-like hemolytic toxin, reported to be initiated under light conditions. However, the association between hemolytic activity (HA) and photosynthesis of P. globosa remained unclear. Light spectra (blue, red, green, and white) and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) were selected as the stressors to stimulate the hemolytic response of P. globosa in relation to the light and dark photosynthesis reaction. Hemolytic activity in P. globosa was sensitive to the light spectrum as it decreased from 93% to nearly undetectable (1.6%) within 10 min of transfer from red (630 nm) to green light (520 nm). This indicates that the vertical transformation of P. globosa from deep to surface waters (dominated by green light and all light spectra, respectively) may drive the hemolytic response in coastal waters. However, regulation of photosynthetic electron transfer in the light reaction of P. globosa was excluded by the evidence of inconsistent response of HA to photosynthetic activity. The biosynthesis of HA may interfere with the pathway of photopigments diadinoxanthin or fucoxanthin, and the metabolism of three- and five-carbon sugars (GAP and Ru5P, respectively), which ultimately lead to changes in the alga's hemolytic carbohydrate metabolism.

Yolk precursor synthesis and deposition in hierarchical follicles and effect on egg production performance of hens.

Egg production of hens is related to ovarian follicles development. The hierarchical follicle development accompanies the deposition of a large amount of yolk precursor. The aim of this study was to illustrate the effects of strain and age on yolk deposition and egg production. The experiment compared yolk synthesis, transport, and deposition in 3 groups of hens: one of a high-yield commercial hybrid laying breed (Jinghong No.1) in 2 stages (35 wk and 75 wk; JH35, JH75) and one of Chinese native breed (Lueyang Black-Boned chicken) at 35 wk (LY35). The results showed that the number of hierarchical follicles in JH35 and JH75 was significantly more than in LY35. At the same time, the yolk weight of the LY35 and JH75 was significantly higher than that of JH35. The expression of apolipoprotein A1 and apolipoprotein B genes in the liver of JH35 was higher than that of JH75. The expression of the very low-density lipoprotein receptor gene in the JH75 ovary was higher than that of the other 2 groups. The plasma concentrations of very low-density lipoprotein and vitellogenin were no significant difference among groups. The yolk deposition in hierarchical follicles based on the fat-soluble dyes measurement meant that the rate of yolk deposition of LY35 was lower than the other 2 groups. In most cases, the yolk deposition of JH75 was higher than that of the other groups, but the process showed greater fluctuation over time. These results meant that the rate and stability of yolk deposition played an essential role in affecting egg performance. In summary, both strain and age were related to egg production, but the 2 factors might impact yolk deposition and egg-laying performance differently. The egg performance may be affected by both yolk precursor synthesis and deposition for different strains, but it may be affected by yolk precursor deposition for the old laying hens.

Insulin-like growth factor-1 regulates follicle selection of hens by promoting proliferation and inhibiting apoptosis of granulosa cells in prehierarchical follicles in vitro.

During the reproduction stage of poultry, a single follicle is selected from a cohort of 6-8 mm small yellow follicles to initiate rapid growth and final ovulation almost daily. In the process, follicle-stimulating hormone (FSH) plays a pivotal role by interacting with intraovarian factors, including insulin-like growth Factor 1 (IGF1). The objective of this study was to analyze whether IGF1 coordinates with FSH to affect the characteristics of granulosa cells from prehierarchical follicles. After treating granulosa cells with 50 ng/mL FSH and 200 ng/mL IGF1, we detected the proliferation and apoptosis of granulosa cells using flow cytometry. The percentage of G1 phase granulosa cells was increased, and the percentage of mitotic cells and apoptotic cells was reduced under IGF1 treatment. The expression levels of the steroidogenic acute regulatory protein gene, cytochrome P450 side-chain cleavage gene and 3ß-hydroxysteroid dehydrogenase gene, which are related to steroidogenic synthesis, were reduced by cotreatment with FSH and IGF1. The expression of the cell proliferation- or apoptosis-related genes cyclin dependent kinase 2, cyclin D2, B-cell leukemia/lymphoma 2, and BCL2 like 1 and the ratio of B-cell leukemia/lymphoma 2/BCL2-associated X were increased by treatment with IGF1. There was a decrease in the expression of caspase3 after treatment with FSH and IGF1. All these results showed that IGF1 reduced the expression of genes involved in progesterone synthesis, stimulated proliferation and inhibited apoptosis in granulosa cells. Thus, IGF1 may be one of the factors involved in affecting FSH responsiveness and maintaining the undifferentiated state of prehierarchical follicles before follicle selection.

Green Synthesis of Carbon Dots and Their Integration into Nylon-11 Nanofibers for Enhanced Mechanical Strength and Biocompatibility.

Carbon dots (CDs) have been extensively explored to show good optical features, low toxicity, and good biocompatibility. Herein, we report the new synthesis of forsythia-derived CDs (F-CDs) and their incorporation into Nylon-11 nanofibers for improved mechanical properties and biocompatibility. F-CDs are prepared from a Chinese herb forsythia via a magnetic hyperthermia method in 90 s without the use of any organic solvents. The as-prepared F-CDs with rich surface functional groups can be well embedded into Nylon-11 nanofibers via electrospinning, providing Nylon-11/F-CD nanofiber mats with remarkably enhanced mechanical properties. With the incorporation of F-CDs at 10 wt% into the Nylon-11 nanofiber mats, the tensile strength increases from 7.5 to 16.6 MPa, and the elongation ratio at break increases from 39% to 125%. Moreover, the Nylon-11/F-CD nanofiber mats exhibit excellent cytocompatibility towards L929 fibroblast cells with cell viability of 96%. These findings may guide the development of various CD-embedded nanofiber mats with good mechanical properties and biocompatibility potentially useful for biomedical applications, such as tissue engineering scaffolds or wound dressing.

Isolation, molecular characterization, immunological and anticoagulatant activities of polysaccharides from frankincense and its vinegar processed product.

Frankincense (FRA), the oily resin consisting of essential oils, boswellic acids (BAs) and polysaccharides, has been used to improve the blood circulation and relieve pain against carbuncles. According to the theory of traditional Chinese medicine, vinegar processed frankincense (VPF) can increase the effects of promoting blood circulation and relieving pain. Existing studies have carried out much on BAs and essential oils. However, the comparative analysis of polysaccharides from FRA and VPF has not been reported. In this paper, two polysaccharides were isolated and purified from FRA and the other two were from VPF, and their structures and physicochemical properties were analyzed. The immunological and anticoagulatant activities of the four polysaccharides were tested in RAW 264.7 cell and Sprague-Dawley rats, respectively. The polysaccharides purified from VPF showed better immunological and anticoagulatant activities than those in FRA. Therefore, polysaccharides may be one of the active substances for the synergistic effect of VPF.

Prenylated isoflavones from the roots of Flemingia philippinensis as potential inhibitors of ß-amyloid aggregation.

In our efforts to find potential agents for the treatment of Alzheimer's disease in naturally occurring compounds, a systematic investigation for the active constituents of Flemingia philippinensis was carried out. Four new prenylated isoflavones, philippinone A-D (1-4), together with six known analogues (5-10), were obtained from the roots of Flemingia philippinensis. Their structures were established through extensive physical and spectroscopic data analysis. All the isolates were evaluated for their inhibitory effect of self-induced Aß aggregation among which compound 5 showed significant Aß aggregation inhibitory ability with the inhibitory rate of 70.56%. The results of molecular docking experiment for compounds 1 and 6 corresponded to that of the thioflavin-T assay. Moreover, the results further clarified the effects of different substituent group of tested compounds on the Aß aggregation inhibition. A preliminary structure-activity relationship is further discussed. Our results suggested that the isoflavonoids may mitigate the progression of AD and compounds 2 and 5 may be a candidate in the treatment of AD.

Size-dependent melting thermodynamics of nanorods in theory and experiment.

Compared with other morphological nanomaterials, nanorods have many unique properties that are closely related to their thermal stability. However, current studies on melting thermodynamic theory of nanorods are still not perfect, and the mechanism and the quantitative regularities of the effect of size of nanorods on melting thermodynamics still remain unclear. Herein, we proposed a melting model of nanorods, derived the thermodynamic relations (free of any adjustable parameters) between the melting temperature, melting enthalpy, and melting entropy, respectively, and the radius of nanorods, and discussed the mechanism of the effect of nanorods and the size dependences of melting thermodynamic properties. Experimentally, taking the melting of Se nanorods as an experimental system, Se nanorods with different diameters were prepared by a Na2SeSO3 disproportionation method, and then the melting temperature and melting thermodynamic properties were determined by differential scanning calorimetry. The effects of the diameter of Se nanorods on the melting temperature and the melting thermodynamic properties were obtained. The experimental results are consistent with the theoretical relations. Both theoretical and experimental results demonstrate that the radius and length of nanorods have significant effects on the melting temperature and the melting thermodynamic properties; for nanorods with a large aspect ratio, the main factors of influence are interfacial tension and radius. Compared with spherical nanoparticles with the same radius, the reduced values of the melting temperature and the thermodynamic properties of nanorods are just half of those corresponding to spherical nanoparticles; the melting temperature, the melting enthalpy, and the melting entropy decrease with the decrease in the radius, and when the radius exceeds 10 nm, these physical quantities are all linearly related to the reciprocal of the radius. The theory can describe the quantitative size-dependent melting thermodynamic properties of nanorods, explain and predict the melting behaviors of nanorods.