Decay

衰变
  • 文章类型: Journal Article
    了解严重急性呼吸系统综合症冠状病毒2(SARS-CoV-2)在废水和环境水域中的衰减特征对于多种应用非常重要,包括评估与处理废水样品相关的暴露风险。与废水污染的环境水域中的娱乐相关的公共卫生风险,以及对废水流行病学(WBE)结果的更好理解和解释。我们评估了在代表季节性波动的温度条件下,废水和环境水中感染性SARS-CoV-2和病毒RNA的衰减率。将传染性病毒接种在高压灭菌的主要废水中,最终脱氯废水,湖水,和海水,终浓度为每毫升6.26±0.07log10斑块形成单位。每个悬浮液在4°孵育,25°,37°C样本最初是按小时收集的,然后大约每隔一天15天。通过使用VeroE6细胞系的噬斑测定分析所有样品的感染性病毒。使用美国CDC的N1和N2逆转录酶定量聚合酶链反应(RT-qPCR)测定对病毒基因拷贝水平进行定量。与病毒RNA相比,感染性病毒的腐烂速度明显更快(p≤0.0214),无论孵育条件如何,在研究期间都会持续存在。与其他类型的水相比,初级处理废水的初始损失(播种后15分钟内)以及传染性SARS-CoV-2的腐烂明显更快(p≤0.0387),但是直到第15天,病毒RNA才在该基质中明显降解。总的来说,温度是衰变最重要的驱动因素,24小时后,在37°C下在任何类型的水中均未检测到传染性SARS-CoV-2。此外,与CDCN1相比,CDCN2基因检测目标在升高的温度下显著更快地衰减(p≤0.0174),这对于WBE方法的RT-qPCR检测选择具有重要意义.
    Understanding the decay characteristics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in wastewater and ambient waters is important for multiple applications including assessment of risk of exposure associated with handling wastewater samples, public health risk associated with recreation in wastewater polluted ambient waters and better understanding and interpretation of wastewater-based epidemiology (WBE) results. We evaluated the decay rates of infectious SARS-CoV-2 and viral RNA in wastewater and ambient waters under temperature regimes representative of seasonal fluctuations. Infectious virus was seeded in autoclaved primary wastewater effluent, final dechlorinated wastewater effluent, lake water, and marine water at a final concentration of 6.26 ± 0.07 log10 plaque forming units per milliliter. Each suspension was incubated at either 4°, 25°, and 37 °C. Samples were initially collected on an hourly basis, then approximately every other day for 15 days. All samples were analyzed for infectious virus via a plaque assay using the Vero E6 cell line, and viral gene copy levels were quantified with the US CDC\'s N1 and N2 reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) assays. The infectious virus decayed significantly faster (p ≤ 0.0214) compared to viral RNA, which persisted for the duration of the study irrespective of the incubation conditions. The initial loss (within 15 min of seeding) as well as decay of infectious SARS-CoV-2 was significantly faster (p ≤ 0.0387) in primary treated wastewater compared to other water types, but viral RNA did not degrade appreciably in this matrix until day 15. Overall, temperature was the most important driver of decay, and after 24 h, no infectious SARS-CoV-2 was detected at 37 °C in any water type. Moreover, the CDC N2 gene assay target decayed significantly (p ≤ 0.0174) faster at elevated temperatures compared to CDC N1, which has important implications for RT-qPCR assay selection for WBE approach.
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  • 文章类型: Journal Article
    这项研究的主要目的,作为计划保护工作的一部分,是为了揭示本土生物膜的各个方面,这些生物膜与在斯洛文尼亚的石灰石RoanecMithraeum纪念碑上发生的许多恶化症状的形成有关。使用最先进的测序技术,将真菌生物组数据与通过大量光和光谱(FTIR和拉曼)显微镜分析进行的观察相结合,指出了上皮性地衣Gyalectajenensis及其光生物,富含类胡萝卜素的Trentepohliaaurea,作为石灰岩表面鲑鱼色色素变化的起源。此外,纪念碑上主要恶化症状的发展,即,活检,是由代表性的疣科科(Verrucariasp。)与草酸介导的石灰石溶解相结合。苔藓真菌的统治,作为主要的变质剂,在浮雕和周围的石灰石上,此外,在FUNGuild分析中,苔藓化和共生生物组的相对丰度较高。获得的结果不仅提高了人们对这种经常发生但经常被忽视的极端性石头遗产变质剂的认识,而且为开发适用于原位保存类似受影响的石灰石古迹的有效生物防治制剂提供了必要的基础。
    The primary purpose of the study, as part of the planned conservation work, was to uncover all aspects of autochthonous biofilm pertaining to the formation of numerous deterioration symptoms occurring on the limestone Rožanec Mithraeum monument in Slovenia. Using state-of-the-art sequencing technologies combining mycobiome data with observations made via numerous light and spectroscopic (FTIR and Raman) microscopy analyses pointed out to epilithic lichen Gyalecta jenensis and its photobiont, carotenoid-rich Trentepohlia aurea, as the origin of salmon-hued pigmented alterations of limestone surface. Furthermore, the development of the main deterioration symptom on the monument, i.e., biopitting, was instigated by the formation of typical endolithic thalli and ascomata of representative Verrucariaceae family (Verrucaria sp.) in conjunction with the oxalic acid-mediated dissolution of limestone. The domination of lichenized fungi, as the main deterioration agents, both on the relief and surrounding limestone, was additionally supported by the high relative abundance of lichenized and symbiotroph groups in FUNGuild analysis. Obtained results not only upgraded knowledge of this frequently occurring but often overlooked group of extremophilic stone heritage deteriogens but also provided a necessary groundwork for the development of efficient biocontrol formulation applicable in situ for the preservation of similarly affected limestone monuments.
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  • 文章类型: Journal Article
    废水监测(WWS)作为一种快速、敏感,以及用于监测社区中各种病原体的具有成本效益的工具。WWS用于评估疾病的时空趋势,并确定其早期出现和复发,以及检测新的和突变的变体。然而,病原体的脱落率显着取决于疾病严重程度等因素,受影响者的生理机能,和病原体类型。此外,病原体在污水处理系统中可能表现出不同的命运和腐烂动力学。可变的脱落率和腐烂动力学可能会影响废水中病原体的检测。这可能会影响对结果的解释和WWS研究的结论。当选择候选病原体进行监测时,必须考虑其特点,如果数据不容易获得,命运等因素,衰变,和脱落率需要评估或至少与可获得此类数据的类似病原体进行比较。
    Wastewater surveillance (WWS) has received significant attention as a rapid, sensitive, and cost-effective tool for monitoring various pathogens in a community. WWS is employed to assess the spatial and temporal trends of diseases and identify their early appearances and reappearances, as well as to detect novel and mutated variants. However, the shedding rates of pathogens vary significantly depending on factors such as disease severity, the physiology of affected individuals, and the characteristics of pathogen. Furthermore, pathogens may exhibit differential fate and decay kinetics in the sewerage system. Variable shedding rates and decay kinetics may affect the detection of pathogens in wastewater. This may influence the interpretation of results and the conclusions of WWS studies. When selecting a pathogen for WWS, it is essential to consider it\'s specific characteristics. If data are not readily available, factors such as fate, decay, and shedding rates should be assessed before conducting surveillance. Alternatively, these factors can be compared to those of similar pathogens for which such data are available.
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  • 文章类型: Journal Article
    这项研究评估了盐偏亚硫酸氢钠(SMB)的功效,碳酸氢铵,碳酸氢钠,和正磷酸二氢钾首先在体外对抗主要的采后果腐病真菌,交替菌,灰葡萄孢菌,意大利青霉,和指状青霉。结果表明,0.2%的SMB完全抑制了真菌菌丝的生长。碳酸氢铵和碳酸氢钠在抑制菌丝体生长的效果在0.2%时较差,从57.6%到77.6%不等。效果最差的是正磷酸二氢钾。还在接种了最致病真菌的受伤苹果上进行了体内实验,B.cinerea,并用浓度为0.2、0.5、1、2和3%的SMB处理,无论是预防性的还是治疗性的。基于衰减大小的结果表明,SMB,当用作预防性治疗时,功效降低,即使浓度最高。然而,这种盐被证明是非常有效的治疗0.5%,因为腐烂被完全阻止。我们的结果表明,作为治愈性治疗,用于收获后处理的SMB的合适浓度为0.5%。另一方面,1%剂量诱导伤口周围植物毒性的发作。为了评估植物毒性反应的程度,将较高浓度的1-4%SMB应用于受伤的果实。苹果和橙子接种或不接种灰芽孢杆菌和指状芽孢杆菌,分别。1-4%的剂量以围绕果实表皮上伤口的变色环的形式引起植物毒性;随着SMB浓度的增加,这种植物毒性增大。苹果和橙子的植物毒性特征相似。方法学程序使得可以进行SMB植物毒性的定量评估。该方法被认为是一种易于使用的技术,用于定量估计抗真菌化合物对收获后果实的植物毒性。
    This study evaluates the efficacy of the salts sodium metabisulfite (SMB), ammonium bicarbonate, sodium bicarbonate, and potassium dihydrogen orthophosphate first in vitro against the main postharvest fruit rot fungi, Alternaria alternata, Botrytis cinerea, Penicillium italicum, and Penicillium digitatum. Results showed that 0.2% SMB completely inhibited the mycelium growth of the fungal species. Ammonium bicarbonate and sodium bicarbonate were less effective at 0.2% in inhibiting mycelial growth, ranging from 57.6% to 77.6%. The least effective was potassium dihydrogen orthophosphate. Experiments were also performed in vivo on wounded apples inoculated with the most pathogenic fungus, B. cinerea, and treated with SMB at concentrations of 0.2, 0.5, 1, 2, and 3%, both preventively and curatively. Results based on the decay size showed that SMB, when used as a preventive treatment, had a reduced efficacy, even with the highest concentration. However, this salt proved to be very effective at 0.5% in curative treatment since the decay was completely blocked. Our results suggest that the appropriate concentration of SMB for post-harvest treatment is 0.5% as a curative treatment. On the other hand, the 1% dose induced the onset of phytotoxicity around the wound. To assess the extent of the phytotoxicity reaction, higher concentrations of 1-4% SMB were applied to wounded fruit. Apples and oranges were inoculated or not with B. cinerea and P. digitatum, respectively. Doses of 1-4% induced phytotoxicity in the form of a discolored ring surrounding the wound on the epidermis of the fruit; this phytotoxicity enlarged as the concentration of SMB increased. The phytotoxic features were similar on apples and oranges. The methodological procedure made it possible to carry out a quantitative assessment of SMB phytotoxicity. This method is proposed as an easy-to-use technique for quantitatively estimating the phytotoxicity of antifungal compounds on post-harvest fruit.
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  • 文章类型: Journal Article
    麝香葡萄(圆叶葡萄。)性质微妙,保质期短。采后技术,例如具有减少的氧气(O2)和升高的二氧化碳(CO2)的气调包装(MAP),可以以更好的质量提高采后储存寿命。在目前的实验中,麝香葡萄黑色和青铜色品种的物理和生化品质属性(\'Supreme\'和\'GrannyVal\',分别)在活性MAP中进行评估。水果装在塑料托盘里,用防渗膜密封,并将CO2引入包装中。MAP是由涂有专有半透性树脂的刚性微穿孔塑料贴片制成的,将其施加在托盘中的孔上;具有相同尺寸的没有贴片的孔的包装是对照。将水果在4°C下储存42天(6周)。MAP导致两个品种的腐烂发生率显着降低,并且在长达28天的储存中保持了更好的果实硬度,并减少了“Supreme”果实的颜色变化。虽然MAP并不影响麝香葡萄的生化品质,总抗氧化剂最初增加,然后在储存过程中减少,无论包装处理。在储存过程中还发现总酚含量显著线性增加,无论采用何种治疗方法。总的来说,当前研究的结果表明,MAP可以是一种有效的技术,可以增加麝香葡萄的储存时间,并更好地保留身体质量,而不影响生化属性。
    Muscadine grapes (Vitis rotundifolia Michx.) are delicate in nature with short shelf life. Postharvest technologies like modified atmosphere packaging (MAP) with reduced oxygen (O2) and elevated carbon dioxide (CO2) could increase the postharvest storage life with better quality. In the current experiment, physical and biochemical quality attributes of black and bronze cultivars of muscadine grapes (\'Supreme\' and \'Granny Val\', respectively) were evaluated in active MAP. Fruit were packed in plastic trays, sealed with impermeable film, and CO2 was introduced into the package. The MAP was created by a rigid microperforated plastic patch coated with a proprietary semipermeable resin, which was applied over a hole in the tray; packages with the same size hole without a patch were the control. Fruit were stored at 4°C for 42 days (6 weeks). MAP resulted in significantly lower decay incidence and better retention of fruit firmness for up to 28 days of storage in both cultivars as well as reducing color changes in \'Supreme\' fruit. Although MAP did not affect the biochemical quality of muscadine grapes, total antioxidants increased initially and then decreased during storage, irrespective of packaging treatments. A significant linear increase in total phenolic content was also found during storage, regardless of treatments applied. Overall, the results of the current study demonstrate that MAP can be an affective technology to increase storage duration of muscadines with better retention of physical quality, without affecting the biochemical attributes.
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  • 文章类型: Journal Article
    最大摄氧量(VO2max)是耐力性能的重要决定因素。热适应/适应(HA/HAz)引起耐久性能的改善。热暴露减少后,间歇性热训练(IHT)可以缓解HA/HAz适应衰减;然而,相应的VO2max响应未知。
    HAz/HA后保持VO2max;IHT减轻HAz/HA后有氧功率的下降。
    介入研究。
    3级。
    总共27名男性耐力运动员(平均值±SD;年龄,36±12岁;体重,73.03±8.97kg;高度,178.81±6.39cm)在5个时间点完成了VO2max测试;基线,后HAZ,后HA,以及IHT的第4周和第8周(IHT4,IHT8)。基线测试后,参与者完成HAZ,之前是5天的HA涉及运动,以在高温下诱导高温60分钟(环境温度,39.13±1.37°C;相对湿度,51.08±8.42%)。参与者被随机分配到3个IHT组中的1个:每周一次,每周两次,或者没有IHT。VO2max的差异,VO2max(vVO2)时的速度,和最大心率(HRmax)在所有5个时间点使用重复测量方差分析和Bonferroni校正后进行分析。
    基线之间未观察到明显的VO2max或vVO2差异,后HAZ,或后HA(分别为P=0.36和P=0.09)。在HA后,VO2max或vVO2没有发现显著的组或时间效应,IHT4和IHT8(分别为P=0.67和P=0.21)。在基线和后HA测试之间观察到显著的HRmax差异(P<0.01)。HA后无显著组或时间HRmax差异,IHT4和IHT8(P=0.59)。
    在HA/HAz和IHT后,耐力跑步者的VO2max并未降低,这可能是由于参与者的类似有氧训练状态和高有氧健身水平。
    HAz/HA和IHT保持耐力跑步者的有氧力量,HAZ/HA降低了HRmax。
    UNASSIGNED: Maximal oxygen uptake (VO2max) is an important determinant of endurance performance. Heat acclimation/acclimatization (HA/HAz) elicits improvements in endurance performance. Upon heat exposure reduction, intermittent heat training (IHT) may alleviate HA/HAz adaptation decay; however, corresponding VO2max responses are unknown.
    UNASSIGNED: VO2max is maintained after HAz/HA; IHT mitigates decrements in aerobic power after HAz/HA.
    UNASSIGNED: Interventional study.
    UNASSIGNED: Level 3.
    UNASSIGNED: A total of 27 male endurance runners (mean ± SD; age, 36 ± 12 years; body mass, 73.03 ± 8.97 kg; height, 178.81 ± 6.39 cm) completed VO2max testing at 5 timepoints; baseline, post-HAz, post-HA, and weeks 4 and 8 of IHT (IHT4, IHT8). After baseline testing, participants completed HAz, preceded by 5 days of HA involving exercise to induce hyperthermia for 60 minutes in the heat (ambient temperature, 39.13 ± 1.37°C; relative humidity, 51.08 ± 8.42%). Participants were assigned randomly to 1 of 3 IHT groups: once-weekly, twice-weekly, or no IHT. Differences in VO2max, velocity at VO2max (vVO2), and maximal heart rate (HRmax) at all 5 timepoints were analyzed using repeated-measure analyses of variance with Bonferroni corrections post hoc.
    UNASSIGNED: No significant VO2max or vVO2 differences were observed between baseline, post-HAz, or post-HA (P = 0.36 and P = 0.09, respectively). No significant group or time effects were identified for VO2max or vVO2 at post-HA, IHT4, and IHT8 (P = 0.67 and P = 0.21, respectively). Significant HRmax differences were observed between baseline and post-HA tests (P < 0.01). No significant group or time HRmax differences shown for post-HA, IHT4, and IHT8 (P = 0.59).
    UNASSIGNED: VO2max was not reduced among endurance runners after HA/HAz and IHT potentially due to participants\' similar aerobic training status and high aerobic fitness levels.
    UNASSIGNED: HAz/HA and IHT maintain aerobic power in endurance runners, with HAz/HA procuring reductions in HRmax.
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  • 文章类型: Journal Article
    本研究为污水相关标记物建立了特定地点的基于风险的阈值(RBT),包括拟杆菌HF183(HF183),LachnospiraceaeLachno3(Lachno3),交叉组装噬菌体(CrAssphage),和辣椒轻度斑驳病毒(PMMoV),利用定量微生物风险评估(QMRA)对休闲河口水域(EW)进行评估。QMRA模型模拟了摄入未经处理的污水污染的EW带来的健康风险。考虑到特定地点的衰变率以及标记和病原体(人类诺如病毒;HNoV)的浓度,估计了RBT,帮助识别沐浴季节的高危天数。结果表明,在10天内,新鲜(第0天)和老化(第1天至第10天)的污水污染情况下,RBT浓度会有所不同。HF183最初表现出最高的RBT(26,600GC/100mL),但随着老化而迅速下降(第10天为2570至3120GC/100mL),而Lachno3和CrAssphage保持相对稳定。PMMoV,尽管初始浓度较低(3920GC/100mL),表现出增加的RBT(4700至6440GC/100mL)随着老化,由于其衰减速率较慢。敏感性分析显示HNoV浓度是最有影响的参数。河口位置标记物浓度与中位RBT的比较显示标记物超标的实例,提示潜在的健康风险。在EW中观察到的细菌和病毒标记物浓度之间的差异突出了需要优化的样品浓度方法和同时测量多个标记物,以增强风险预测。未来的研究将探讨多重标记在风险管理中的效用。总的来说,这项研究有助于更好地了解娱乐水域中的人类健康风险,协助监管机构,和水质管理人员为风险优先排序和缓解战略做出有效决策。
    This study establishes site-specific risk-based threshold (RBT) concentrations for sewage-associated markers, including Bacteroides HF183 (HF183), Lachnospiraceae Lachno3 (Lachno3), cross-assembly phage (CrAssphage), and pepper mild mottle virus (PMMoV), utilizing quantitative microbial risk assessment (QMRA) for recreational estuarine waters (EW). The QMRA model calculates a RBT concentration corresponding to a selected target illness risk for ingestion of EW contaminated with untreated sewage. RBT concentrations were estimated considering site-specific decay rates and concentrations of markers and reference pathogen (human norovirus; HNoV), aiding in the identification of high-risk days during the swimming season. Results indicated varying RBT concentrations for fresh (Day 0) and aged (Days 1 to 10) sewage contamination scenarios over 10 days. HF183 exhibited the highest RBT concentration (26,600 gene copis (GC)/100 mL) initially but decreased rapidly with aging (2570 to 3120 GC/100 mL on Day 10) depending on the decay rates, while Lachno3 and CrAssphage remained relatively stable. PMMoV, despite lower initial RBT (3920 GC/100 mL), exhibited increased RBT (4700 to 6440 GC/100 mL) with aging due to its slower decay rate compared to HNoV. Sensitivity analysis revealed HNoV concentrations as the most influential parameter. Comparison of marker concentrations in estuarine locations with RBT concentrations showed instances of marker exceedance, suggesting days of potential higher risks. The observed discrepancies between bacterial and viral marker concentrations in EW highlight the need for optimized sample concentration method and simultaneous measurement of multiple markers for enhanced risk predictions. Future research will explore the utility of multiple markers in risk management. Overall, this study contributes to better understanding human health risks in recreational waters, aiding regulators, and water quality managers in effective decision-making for risk prioritization and mitigation strategies.
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  • 文章类型: Journal Article
    It has been proposed that ectomycorrhizal fungi can reduce decomposition while arbuscular mycorrhizal fungi may enhance it. These phenomena are known as the \'Gadgil effect\' and \'priming effect\', respectively. However, it is unclear which one predominates globally. We evaluated whether mycorrhizal fungi decrease or increase decomposition, and identified conditions that mediate this effect. We obtained decomposition data from 43 studies (97 trials) conducted in field or laboratory settings that controlled the access of mycorrhizal fungi to substrates colonized by saprotrophs. Across studies, mycorrhizal fungi promoted decomposition of different substrates by 6.7% overall by favoring the priming effect over the Gadgil effect. However, we observed significant variation among studies. The substrate C : N ratio and absolute latitude influenced the effect of mycorrhizal fungi on decomposition and contributed to the variation. Specifically, mycorrhizal fungi increased decomposition at low substrate C : N and absolute latitude, but there was no discernable effect at high values. Unexpectedly, the effect of mycorrhizal fungi was not influenced by the mycorrhizal type. Our findings challenge previous assumptions about the universality of the Gadgil effect but highlight the potential of mycorrhizal fungi to negatively influence soil carbon storage by promoting the priming effect.
    Los hongos ectomicorrízicos puden reducir la descomposición mientras que los hongos micorrízico‐arbusculares pueden potenciarla. Ambos fenómenos son conocidos como “Gadgil effect” y “priming effect”, respectivamente. Sin embargo, no es claro cuál predomina mundialmente. En este trabajo evaluamos si los hongos micorrízicos disminuyen o promueven la descomposición, e identificamos las condiciones que regulan este efecto. Para ello, recopilamos datos de descomposición de 43 estudios (97 observaciones) realizados en condiciones de campo o laboratorio que controlaron el acceso de los hongos micorrízicos a sustratos colonizados por saprótrofos. Los hongos micorrízicos promovieron la descomposición de diferentes sustratos en un 6.7%. Sin embargo, observamos una variación significativa entre estudios. La relación C : N del sustrato y la latitud influyeron en el efecto de los hongos micorrícicos sobre la descomposición y contribuyeron a la variabilidad. Específicamente, los hongos micorrízicos aumentaron la descomposición a valores bajos de C : N del sustrato y latitud, pero no hubo un efecto discernible en valores altos. Inesperadamente, el tipo de micorriza no influyó en el efecto de los hongos micorrízicos. Nuestros hallazgos cuestionan la universalidad del Gadgil effect, y resaltan el potencial de los hongos micorrízicos para influir negativamente en el almacenamiento de carbono del suelo al promover el priming effect.
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  • 文章类型: Case Reports
    死亡原因被定义为导致生理变化导致死亡的自然疾病或伤害。死亡方式是指死亡周围的情况。分解,特别是在高级阶段,在事后检查中造成困难,因为它包括导致重要的可观察发现和特征丢失的过程。在分解的尸体中观察到的创伤可以通过其重要特征和对致命结局的发生的意义来分析,这有助于确定死亡的原因和方式。一具几乎完全骨骼化的尸体被医科大学法医学和道义学系录取,索菲亚,保加利亚。除了回答死后间隔的义务之外,人类学和生物学特征是什么,必须确定死亡的原因和方式,以便将案件归类为刑事与否。死因是由形态学发现-头部枪伤确定的,通过大脑。由于受伤区域没有软组织,死亡方式尚未确定。结论是没有足够的法医数据来回答这是自杀,凶杀案,甚至是意外.
    Cause of death is defined as a natural disease or injury that led to physiologic changes resulting in death. Manner of death refers to the circumstances surrounding death. Decomposition, especially in advanced stages, creates difficulties in post-mortem examination for it encompasses the processes that lead to the loss of important observable findings and features. Traumatic injuries observed in decomposed cadavers might be analyzed by their vital features and significance for the occurrence of fatal outcomes that help determine the cause and manner of death. An almost fully skeletonized cadaver was admitted to the Department of Forensic Medicine and Deontology at The Medical University, Sofia, Bulgaria. Along with the obligation to answer the post-mortem interval, what were the anthropological and biological features, the cause and manner of death had to be determined in order to classify the case as criminal or not. The cause of death was established by the morphological finding - gunshot injury of the head, passing the brain. The manner of death remained undetermined because of the absence of soft tissues in the areas of the injuries. It was concluded that there was no sufficient forensic data to answer if it was suicide, homicide, or even an accident.
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  • 文章类型: Journal Article
    了解明亮和黑暗激子状态之间的相互作用对于破译低维材料的发光特性至关重要。卤化铅钙钛矿的杰出亮度的起源仍然难以捉摸。这里,我们分析了与温度相关的时间分辨光致发光,以研究在中间限制状态下单个CsPbBr3纳米晶体中明亮和黑暗激子子子能级之间的种群混合。我们提取了亮和暗激子的衰减率,并定量地表明,衰减动力学只能通过二阶声子跃迁来再现。此外,我们发现,任何激子子级排序都与最可能的种群转移机制兼容。卤化铅钙钛矿纳米晶体的显着亮度源于亮到暗和暗到亮转换之间的不对称性降低,该不对称性源于特殊的二阶声子辅助跃迁,该跃迁在低温下冻结了亮暗转换,以及非常快速的辐射复合和亮激子状态的有利简并。
    Understanding the interplay between bright and dark exciton states is crucial for deciphering the luminescence properties of low-dimensional materials. The origin of the outstanding brightness of lead halide perovskites remains elusive. Here, we analyze temperature-dependent time-resolved photoluminescence to investigate the population mixing between bright and dark exciton sublevels in individual CsPbBr3 nanocrystals in the intermediate confinement regime. We extract bright and dark exciton decay rates and show quantitatively that the decay dynamics can only be reproduced with second-order phonon transitions. Furthermore, we find that any exciton sublevel ordering is compatible with the most likely population transfer mechanism. The remarkable brightness of lead halide perovskite nanocrystals rather stems from a reduced asymmetry between bright-to-dark and dark-to-bright conversion originating from the peculiar second-order phonon-assisted transitions that freeze bright-dark conversion at low temperatures together with the very fast radiative recombination and favorable degeneracy of the bright exciton state.
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